Bridge and Pontic Design 2023,by dr. Mohammed Alqadasi.
talking about the principles and considerations for proper bridge and pontic design , the pretreatment assessment and evaluation ,type of fixed partial denture and type of pontic , stage of design,and materials that used.
1) There are two main hardening mechanisms for dental cements - acid-base reactions and polymerization reactions. Common cements that use acid-base reactions include zinc phosphate, polycarboxylate, and glass ionomer cements. Resin cements use a polymerization reaction.
2) Zinc phosphate cement has a long history of success but lacks adhesion and fluoride release. Polycarboxylate cement bonds to tooth structure and has short mixing/working times. Glass ionomer cement releases fluoride and bonds to tooth structure.
3) Resin-modified glass ionomer cement combines the benefits of glass ionomer cement with the strength and handling of resin, providing good early strength and reduced moisture sensitivity.
This document discusses attachments used in prosthodontics. It begins with an introduction to attachments, defining them as mechanical devices used to retain and stabilize prostheses. The document then covers the history, classification, indications, disadvantages, and selection of attachments. It discusses both intracoronal and extracoronal attachments. In summary, the document provides an overview of attachments, their uses in prosthodontics, and factors to consider in selecting the appropriate attachment.
The document describes the key laboratory procedures for fabricating a removable partial denture (RPD) in 8 steps:
1) Duplicating the stone cast and creating an investment cast
2) Waxing the RPD framework using preformed patterns or wrought wire
3) Spruing the waxed framework
4) Investing and burning out the sprued pattern
5) Casting the framework in metal using centrifugal force
6) Removing the casting from the investment
7) Finishing and polishing the framework, including electropolishing
8) Trying in the framework on the patient
It also explains that a work authorization delineates responsibilities and ensures quality control by providing instructions
The document discusses immediate dentures, which are dentures fabricated and inserted immediately following tooth extraction. It describes the different types of immediate dentures, including conventional/classic immediate dentures, interim immediate dentures, labial flange dentures, partial flange dentures, and flangeless/socketed dentures. The advantages of immediate dentures include maintaining a patient's appearance without teeth, providing a bandage effect to extraction sites, and allowing easier adaptation to dentures during healing. However, immediate dentures also present challenges like reduced retention from undercuts caused by remaining posterior teeth.
11.complete denture wax‐up and flasking procedureshammasm
This document discusses the process of waxing up dentures and flasking them for acrylic resin processing. It describes criteria for waxing the upper and lower dentures, including contouring the wax base and arranging the teeth. The flasking process involves investing the wax dentures and casts in dental stone in a flask, followed by wax elimination and packing of the flask with acrylic resin. The flask then undergoes polymerization cycling by heating in a water bath to cure the resin into the final denture bases.
Failures in Fixed Partial Denture
(Prosthodontics FPD- Dental science)
Various types of failures in the fabrication of fixed partial denture
Dr.Sachin Sunny Otta
St.Gregorios Dental College,Kothamangalam,Ernakulam
This analytical review summarizes clinical outcomes of rigid and non-rigid telescopic double-crown retained removable dental prostheses based on 25 studies meeting the inclusion criteria. The review found that the cumulative survival rates of abutment teeth tended to decrease over time, regardless of the rigid or non-rigid type of prosthesis. Additionally, studies with fewer remaining abutment teeth reported lower cumulative survival rates of abutments. The review concluded that strategic implant placement could help increase the survival rates of abutments and prostheses when using double-crown retained removable dental prostheses.
This document discusses different types of bridges used in dentistry. It describes fixed partial dentures, which cannot be removed by the patient and replace one or more missing teeth using retainers, pontics, and connectors. There are four main types of bridges discussed: fixed-fixed bridges which use rigid connectors; fixed-movable bridges which use one fixed and one movable connector; cantilever bridges; and resin-bonded bridges. Key factors in determining the appropriate bridge design include the crown-root ratio and root surface area of the abutment teeth.
1) There are two main hardening mechanisms for dental cements - acid-base reactions and polymerization reactions. Common cements that use acid-base reactions include zinc phosphate, polycarboxylate, and glass ionomer cements. Resin cements use a polymerization reaction.
2) Zinc phosphate cement has a long history of success but lacks adhesion and fluoride release. Polycarboxylate cement bonds to tooth structure and has short mixing/working times. Glass ionomer cement releases fluoride and bonds to tooth structure.
3) Resin-modified glass ionomer cement combines the benefits of glass ionomer cement with the strength and handling of resin, providing good early strength and reduced moisture sensitivity.
This document discusses attachments used in prosthodontics. It begins with an introduction to attachments, defining them as mechanical devices used to retain and stabilize prostheses. The document then covers the history, classification, indications, disadvantages, and selection of attachments. It discusses both intracoronal and extracoronal attachments. In summary, the document provides an overview of attachments, their uses in prosthodontics, and factors to consider in selecting the appropriate attachment.
The document describes the key laboratory procedures for fabricating a removable partial denture (RPD) in 8 steps:
1) Duplicating the stone cast and creating an investment cast
2) Waxing the RPD framework using preformed patterns or wrought wire
3) Spruing the waxed framework
4) Investing and burning out the sprued pattern
5) Casting the framework in metal using centrifugal force
6) Removing the casting from the investment
7) Finishing and polishing the framework, including electropolishing
8) Trying in the framework on the patient
It also explains that a work authorization delineates responsibilities and ensures quality control by providing instructions
The document discusses immediate dentures, which are dentures fabricated and inserted immediately following tooth extraction. It describes the different types of immediate dentures, including conventional/classic immediate dentures, interim immediate dentures, labial flange dentures, partial flange dentures, and flangeless/socketed dentures. The advantages of immediate dentures include maintaining a patient's appearance without teeth, providing a bandage effect to extraction sites, and allowing easier adaptation to dentures during healing. However, immediate dentures also present challenges like reduced retention from undercuts caused by remaining posterior teeth.
11.complete denture wax‐up and flasking procedureshammasm
This document discusses the process of waxing up dentures and flasking them for acrylic resin processing. It describes criteria for waxing the upper and lower dentures, including contouring the wax base and arranging the teeth. The flasking process involves investing the wax dentures and casts in dental stone in a flask, followed by wax elimination and packing of the flask with acrylic resin. The flask then undergoes polymerization cycling by heating in a water bath to cure the resin into the final denture bases.
Failures in Fixed Partial Denture
(Prosthodontics FPD- Dental science)
Various types of failures in the fabrication of fixed partial denture
Dr.Sachin Sunny Otta
St.Gregorios Dental College,Kothamangalam,Ernakulam
This analytical review summarizes clinical outcomes of rigid and non-rigid telescopic double-crown retained removable dental prostheses based on 25 studies meeting the inclusion criteria. The review found that the cumulative survival rates of abutment teeth tended to decrease over time, regardless of the rigid or non-rigid type of prosthesis. Additionally, studies with fewer remaining abutment teeth reported lower cumulative survival rates of abutments. The review concluded that strategic implant placement could help increase the survival rates of abutments and prostheses when using double-crown retained removable dental prostheses.
This document discusses different types of bridges used in dentistry. It describes fixed partial dentures, which cannot be removed by the patient and replace one or more missing teeth using retainers, pontics, and connectors. There are four main types of bridges discussed: fixed-fixed bridges which use rigid connectors; fixed-movable bridges which use one fixed and one movable connector; cantilever bridges; and resin-bonded bridges. Key factors in determining the appropriate bridge design include the crown-root ratio and root surface area of the abutment teeth.
Centric relation is a controversial concept in dentistry that refers to the maxillomandibular relationship where the condyles are in their most anterior and superior position against the articular eminences, allowing purely rotary movement of the mandible. There have been many changes to the definition of centric relation over time as understanding has evolved. It is important for proper functioning and to develop centric occlusion in artificial dentures. However, accurately recording centric relation can be difficult due to various biological, psychological and mechanical factors that must be addressed. Common methods include using interocclusal records with or without central bearing devices as well as functional recording techniques.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Concepts of Complete denture occlusion Amal Kaddah
This document discusses concepts of complete denture occlusion. It provides an overview of the history of denture occlusion philosophies from early carvings of teeth from stone and wood to modern concepts developed in the early 20th century. Key concepts discussed include balanced occlusion, factors affecting balanced occlusion like condylar guidance and incisal guidance, and various occlusion philosophies proposed over time including those by Gysi, Hanau, Pleasure, and Boucher. The document does not conclude on a superior occlusal scheme but notes a balanced articulation appears most appropriate.
1. The document discusses the requirements and materials used for provisional restorations. Provisional restorations must provide good fit, occlusion, contacts, esthetics, contours, and strength while acting as a temporary until the final restoration is fabricated.
2. Common materials used are acrylics and resin composites. Acrylics are most commonly used due to their low cost, esthetics, and versatility but can discolor over time. Resin composites provide better fit and less shrinkage than acrylics.
3. The ideal provisional material would have good handling properties and biocompatibility while providing adequate strength, esthetics, and ease of repair until being replaced by the final
This document discusses establishing occlusion for removable partial dentures (RPDs). It notes that occlusion plays a major role in RPD success. Several methods are described for determining occlusion, including direct apposition of casts if enough teeth remain, making interocclusal records with wax if some teeth remain, and using occlusion rims on record bases if areas are edentulous. The goals of occlusion are outlined as occlusal harmony with remaining teeth, improving relationships if malocclusion exists, restoring vertical dimension, and correcting mandibular rotation from tooth loss. Desirable occlusal contacts include simultaneous bilateral contacts in centric occlusion and working side contacts for distal extension dentures.
Occlusal equilibration is a procedure to precisely alter the occlusal surfaces of teeth to improve the contact pattern. It involves selectively grinding tooth structures that interfere with terminal hinge axis closure, lateral excursion, and protrusive movement. Common tools used include paste, spray or paint to identify contact points requiring adjustment. The basic rules of selective grinding include narrowing cusp tips before reshaping fossae, and adjusting the inclines of upper and lower teeth in opposing directions depending on the path of slide. Occlusal errors in complete dentures can be caused by incorrect registration of the retruded contact position or irregularities during setting and processing of the teeth.
The document provides an overview of esthetics with veneers. It discusses the definitions, history, indications and contraindications of veneers. It describes the processes of shade selection, tooth preparation including principles, rationale and types of preparation. It also discusses provisional restorations, cementation, maintenance and failures of veneers. Recent advancements discussed include feldspathic, lithium disilicate and minimally invasive veneers. In conclusion, veneers are a conservative treatment for improving aesthetics when done according to principles of preparation, cementation and maintenance.
this is a presentation that describes the laboratory procedure in RPD framework fabrication
also has a flow chart in the beginning explaining steps to be done by dentist and steps to be taken by laboratory technician
https://youtu.be/aaJ6gpQohcs
https://youtu.be/REMKSUty0cE
https://youtu.be/fv3_tWZPJIU
https://youtu.be/GeZIbCwqKYU
if you want me to make ppt on some topic do let me know on the comment section of my youtube channel
Provisional restoration in fixed partial denturebhuvanesh4668
This document discusses various techniques for fabricating provisional restorations. It begins by defining provisional restorations and outlining their key requirements and purposes. It then describes common provisional luting materials and different types of provisional restorations that can be used. The remainder of the document focuses on detailing specific techniques for fabricating provisional restorations, including direct fabrication techniques, indirect techniques using impressions or templates, and the use of prefabricated crowns. Key steps are outlined for a variety of techniques.
This document summarizes research on the success rates and complications of resin bonded prostheses (RBPs). It finds that on average, 26% of RBPs experience complications within 4 years, increasing to 28% after 5 years, with debonding being the most common at 21%. Debonding rates are higher for posterior teeth, longer spans, and cantilever designs. Tooth preparation techniques like covering lingual and proximal surfaces, adding proximal grooves or pinholes, and occlusal rests can reduce debonding. Maintaining a minimum of 0.5mm occlusal clearance and 1mm metal thickness also impacts success. Proper diagnosis, treatment planning and cementation techniques are keys to optimizing longevity
Terminology and classification of fixed prosthodontics AlyaaAsaad1
This document provides an introduction to fixed prosthodontics. It defines fixed prosthodontics as the restoration or replacement of teeth with artificial substitutes that are attached to natural teeth, roots, or implants. It discusses different types of crowns and bridges, including full coverage crowns, partial coverage crowns, and fixed partial dentures (bridges). It also classifies crowns and bridges based on factors like material, mode of retention, and location in the mouth. The document aims to give an overview of common fixed prosthodontic treatments and components.
Finishing and polishing of cast metal framework/prosthodontic coursesIndian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Dental Esthetics include the use of bonded ceramic veneers and laminates. This presentation helps to understand various concepts relating to the preparation and utility of such restorations. - Dr. Abhishek John Samuel, MDS (Endodontics)
The document discusses overdentures, which are removable partial or complete dentures that cover and rest on one or more remaining natural teeth, tooth roots, or dental implants. Key points include:
- Retaining natural teeth can preserve alveolar bone and periodontal receptors important for function.
- Abutment teeth are prepared with short copings or left uncovered, and attachments may be added to improve retention.
- Overdentures can improve retention, stability, support and proprioception compared to conventional dentures.
- Proper case selection and maintenance are important for long term success.
This document discusses the history and classification of precision dental attachments. It begins by outlining some of the early developments in attachment designs from the 19th century. It then classifies attachments based on their fabrication method, relationship to abutment teeth, stiffness, and geometric configuration. The advantages and disadvantages of attachments are provided. Key factors in selecting abutment teeth are identified. Requirements for ideal abutment teeth are outlined. Contraindications and the role of attachments in different types of prosthodontic treatments are summarized.
This document discusses principles of removable partial denture design. It covers different types of partial denture support, including tooth-supported and tooth/tissue-supported designs. Key factors in partial denture design include distributing forces, controlling movement, selecting appropriate components, and considering the individual patient's anatomy and needs. Design elements like survey lines, clasps, connectors, and occlusal rests are discussed in terms of their effects on support and stress distribution. The document contrasts the biomechanical considerations between total tooth-supported versus distal extension partial dentures.
Design and fabrication of complete dentures using cadAamir Godil
This document summarizes research on the design and fabrication of complete dentures using CAD/CAM technology. It outlines the conventional denture fabrication process and reviews literature on different CAD/CAM approaches. The fabrication process involves digitizing models, virtually arranging teeth, designing the denture base digitally, and milling resin baseplates before bonding the dentition. CAD/CAM dentures offer advantages like fewer patient visits, improved fit and strength, reduced costs, and reproducibility. However, the summary does not discuss try-in, special occlusal considerations, characterization, or compare CAD/CAM to conventional denture bases.
1. A tooth supported overdenture is a removable partial or complete denture that covers and receives support from one or more remaining natural teeth or dental implants.
2. It provides advantages like ridge preservation, improved retention, stability and support compared to conventional complete dentures.
3. Tooth supported overdentures can be classified based on the type of abutment preparation (coping vs non-coping) and the timing of placement (immediate, interim or definitive).
Indications contraindications and classification of bridges/endodontic coursesIndian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Centric relation is a controversial concept in dentistry that refers to the maxillomandibular relationship where the condyles are in their most anterior and superior position against the articular eminences, allowing purely rotary movement of the mandible. There have been many changes to the definition of centric relation over time as understanding has evolved. It is important for proper functioning and to develop centric occlusion in artificial dentures. However, accurately recording centric relation can be difficult due to various biological, psychological and mechanical factors that must be addressed. Common methods include using interocclusal records with or without central bearing devices as well as functional recording techniques.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Concepts of Complete denture occlusion Amal Kaddah
This document discusses concepts of complete denture occlusion. It provides an overview of the history of denture occlusion philosophies from early carvings of teeth from stone and wood to modern concepts developed in the early 20th century. Key concepts discussed include balanced occlusion, factors affecting balanced occlusion like condylar guidance and incisal guidance, and various occlusion philosophies proposed over time including those by Gysi, Hanau, Pleasure, and Boucher. The document does not conclude on a superior occlusal scheme but notes a balanced articulation appears most appropriate.
1. The document discusses the requirements and materials used for provisional restorations. Provisional restorations must provide good fit, occlusion, contacts, esthetics, contours, and strength while acting as a temporary until the final restoration is fabricated.
2. Common materials used are acrylics and resin composites. Acrylics are most commonly used due to their low cost, esthetics, and versatility but can discolor over time. Resin composites provide better fit and less shrinkage than acrylics.
3. The ideal provisional material would have good handling properties and biocompatibility while providing adequate strength, esthetics, and ease of repair until being replaced by the final
This document discusses establishing occlusion for removable partial dentures (RPDs). It notes that occlusion plays a major role in RPD success. Several methods are described for determining occlusion, including direct apposition of casts if enough teeth remain, making interocclusal records with wax if some teeth remain, and using occlusion rims on record bases if areas are edentulous. The goals of occlusion are outlined as occlusal harmony with remaining teeth, improving relationships if malocclusion exists, restoring vertical dimension, and correcting mandibular rotation from tooth loss. Desirable occlusal contacts include simultaneous bilateral contacts in centric occlusion and working side contacts for distal extension dentures.
Occlusal equilibration is a procedure to precisely alter the occlusal surfaces of teeth to improve the contact pattern. It involves selectively grinding tooth structures that interfere with terminal hinge axis closure, lateral excursion, and protrusive movement. Common tools used include paste, spray or paint to identify contact points requiring adjustment. The basic rules of selective grinding include narrowing cusp tips before reshaping fossae, and adjusting the inclines of upper and lower teeth in opposing directions depending on the path of slide. Occlusal errors in complete dentures can be caused by incorrect registration of the retruded contact position or irregularities during setting and processing of the teeth.
The document provides an overview of esthetics with veneers. It discusses the definitions, history, indications and contraindications of veneers. It describes the processes of shade selection, tooth preparation including principles, rationale and types of preparation. It also discusses provisional restorations, cementation, maintenance and failures of veneers. Recent advancements discussed include feldspathic, lithium disilicate and minimally invasive veneers. In conclusion, veneers are a conservative treatment for improving aesthetics when done according to principles of preparation, cementation and maintenance.
this is a presentation that describes the laboratory procedure in RPD framework fabrication
also has a flow chart in the beginning explaining steps to be done by dentist and steps to be taken by laboratory technician
https://youtu.be/aaJ6gpQohcs
https://youtu.be/REMKSUty0cE
https://youtu.be/fv3_tWZPJIU
https://youtu.be/GeZIbCwqKYU
if you want me to make ppt on some topic do let me know on the comment section of my youtube channel
Provisional restoration in fixed partial denturebhuvanesh4668
This document discusses various techniques for fabricating provisional restorations. It begins by defining provisional restorations and outlining their key requirements and purposes. It then describes common provisional luting materials and different types of provisional restorations that can be used. The remainder of the document focuses on detailing specific techniques for fabricating provisional restorations, including direct fabrication techniques, indirect techniques using impressions or templates, and the use of prefabricated crowns. Key steps are outlined for a variety of techniques.
This document summarizes research on the success rates and complications of resin bonded prostheses (RBPs). It finds that on average, 26% of RBPs experience complications within 4 years, increasing to 28% after 5 years, with debonding being the most common at 21%. Debonding rates are higher for posterior teeth, longer spans, and cantilever designs. Tooth preparation techniques like covering lingual and proximal surfaces, adding proximal grooves or pinholes, and occlusal rests can reduce debonding. Maintaining a minimum of 0.5mm occlusal clearance and 1mm metal thickness also impacts success. Proper diagnosis, treatment planning and cementation techniques are keys to optimizing longevity
Terminology and classification of fixed prosthodontics AlyaaAsaad1
This document provides an introduction to fixed prosthodontics. It defines fixed prosthodontics as the restoration or replacement of teeth with artificial substitutes that are attached to natural teeth, roots, or implants. It discusses different types of crowns and bridges, including full coverage crowns, partial coverage crowns, and fixed partial dentures (bridges). It also classifies crowns and bridges based on factors like material, mode of retention, and location in the mouth. The document aims to give an overview of common fixed prosthodontic treatments and components.
Finishing and polishing of cast metal framework/prosthodontic coursesIndian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Dental Esthetics include the use of bonded ceramic veneers and laminates. This presentation helps to understand various concepts relating to the preparation and utility of such restorations. - Dr. Abhishek John Samuel, MDS (Endodontics)
The document discusses overdentures, which are removable partial or complete dentures that cover and rest on one or more remaining natural teeth, tooth roots, or dental implants. Key points include:
- Retaining natural teeth can preserve alveolar bone and periodontal receptors important for function.
- Abutment teeth are prepared with short copings or left uncovered, and attachments may be added to improve retention.
- Overdentures can improve retention, stability, support and proprioception compared to conventional dentures.
- Proper case selection and maintenance are important for long term success.
This document discusses the history and classification of precision dental attachments. It begins by outlining some of the early developments in attachment designs from the 19th century. It then classifies attachments based on their fabrication method, relationship to abutment teeth, stiffness, and geometric configuration. The advantages and disadvantages of attachments are provided. Key factors in selecting abutment teeth are identified. Requirements for ideal abutment teeth are outlined. Contraindications and the role of attachments in different types of prosthodontic treatments are summarized.
This document discusses principles of removable partial denture design. It covers different types of partial denture support, including tooth-supported and tooth/tissue-supported designs. Key factors in partial denture design include distributing forces, controlling movement, selecting appropriate components, and considering the individual patient's anatomy and needs. Design elements like survey lines, clasps, connectors, and occlusal rests are discussed in terms of their effects on support and stress distribution. The document contrasts the biomechanical considerations between total tooth-supported versus distal extension partial dentures.
Design and fabrication of complete dentures using cadAamir Godil
This document summarizes research on the design and fabrication of complete dentures using CAD/CAM technology. It outlines the conventional denture fabrication process and reviews literature on different CAD/CAM approaches. The fabrication process involves digitizing models, virtually arranging teeth, designing the denture base digitally, and milling resin baseplates before bonding the dentition. CAD/CAM dentures offer advantages like fewer patient visits, improved fit and strength, reduced costs, and reproducibility. However, the summary does not discuss try-in, special occlusal considerations, characterization, or compare CAD/CAM to conventional denture bases.
1. A tooth supported overdenture is a removable partial or complete denture that covers and receives support from one or more remaining natural teeth or dental implants.
2. It provides advantages like ridge preservation, improved retention, stability and support compared to conventional complete dentures.
3. Tooth supported overdentures can be classified based on the type of abutment preparation (coping vs non-coping) and the timing of placement (immediate, interim or definitive).
Indications contraindications and classification of bridges/endodontic coursesIndian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Overdentures /certified fixed orthodontic courses by Indian dental academyIndian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
abutment selection in fixed partial denture.pptxRajSalvi5
This document discusses factors to consider when selecting abutment teeth for fixed partial dentures. Thorough diagnostic evaluation including diagnostic casts, radiographs and clinical examination are needed to assess root morphology, bone support, crown-root ratios and other anatomical and pathological factors. Proper identification of abutment teeth requires consideration of these diagnostic factors as well as other issues like occlusion, opposing dentition and esthetics to design fixed prostheses that are retained and supported by abutment teeth.
The scope of fixed prosthodontics treatment can range from the restoration of a single tooth to the rehabilitation of the entire occlusion. Single teeth can be restored to full function, and improvement in
esthetics can be achieved. Missing teeth can be replaced with fixed prostheses that will improve patient comfort and masticatory ability, maintain the health and integrity of the dental arches, and, in many instances, elevate the patient’s self-image.
This document provides an overview of overdentures, including definitions, indications, classifications, attachments, and the construction process. An overdenture is a removable partial or complete denture that is supported by retained roots, implants, or a combination. Key points include:
- Overdentures are indicated when a few teeth remain that are not suitable for a fixed bridge but can help support a denture.
- Classification includes tooth-supported, implant-supported, and combinations. Attachments can improve retention.
- Construction involves preparing and reducing abutment teeth, taking impressions, and inserting a denture that is relieved over the abutments. Excellent oral hygiene is important for maintenance.
This document discusses resin bonded fixed partial dentures (RBFPDs). It defines RBFPDs as prostheses that are luted to tooth structure using composite resin. Various types are described, including cantilever, fixed-fixed, and hybrid bridges. Advantages include reduced cost and minimal tooth preparation. Indications are for replacing single missing teeth with caries-free abutments. A case example describes using an RBFPD to replace a missing mandibular incisor and splint mobile abutment teeth.
Treatment planning and diagnosis for fpd / oral surgery courses Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.
Space maintainers are appliances used to maintain space or regain minor amounts of space lost after a primary tooth is lost. There are several types of space maintainers including fixed appliances like band and loop, lingual arch, and distal shoe appliances as well as removable partial dentures. Key factors in determining the appropriate space maintainer include the amount of time since tooth loss, dental age of the patient, amount of bone covering the unerupted tooth, and sequence of eruption of surrounding teeth. Space maintainers aim to guide unerupted teeth into proper positions and prevent over-eruption of opposing teeth.
1) The document reviews principles for restoring endodontically treated teeth, including the use of posts, cores, and final restorations. It discusses when posts are necessary, types of post materials and designs, and post space preparation techniques.
2) Fiber-reinforced posts are presented as a promising newer option that better match the elasticity of tooth structure compared to rigid metal posts, and can bond effectively to resin cement and composite cores.
3) While posts are primarily used to retain cores when there is insufficient remaining tooth structure, the document notes there is debate around whether posts actually strengthen teeth, as their insertion can weaken roots; careful treatment planning is important.
Designing removable partial dentures around difficult dentitionShelaKusuma1
This document discusses challenges in designing removable partial dentures around difficult dentition. It describes problems caused by overerupted teeth, tilted teeth, drifted teeth, and increased overbite/overjet. Solutions proposed include modifying the partial denture design, reducing tooth size through enameloplasty, orthodontic treatment, and increasing or decreasing vertical dimension of occlusion as needed in each case. The goal is to restore function and aesthetics while managing challenges from anatomical variations in remaining teeth.
Design of a fixed Partial Denture (with Abutment Tooth Preparation)Taseef Hasan Farook
A simplified take on the steps to designing a Fixed partial denture. This presentation also includes an overview of abutment preparation, associated finishes and methods of impression taking prior to the designing of the prosthesis itself
Other forms of removable partial denture Amal Kaddah
This document discusses various types of removable partial dentures (RPDs), including unilateral RPDs, swing-lock RPDs, overlay partial dentures, implant-supported RPDs, and attachments for RPDs. It provides details on the design, indications, advantages and disadvantages of each type. Key types discussed include overlay partial dentures, which are constructed over remaining natural teeth for additional support and retention, and attachments for RPDs, which can improve retention and are either precision attachments that are prefabricated, or semi-precision attachments that are fabricated in the dental laboratory.
2- b. Basic principles for designing Kennedy class II, III and IV Removable P...AmalKaddah1
1-a. Basic principles for designing the removable partial denture (class I partial denture design)
Introduction.
Objectives and Functions of RPD.
Factors that affect RPD design.
Basic principles for designing Kennedy class I partial denture.
2- b. Basic principles for designing Kennedy class II, III and IV Removable Partial Denture(RPD)
2- b. Basic principles for designing Kennedy class II, III and IV RPD - Copy....AmalKaddah1
The document discusses principles of removable partial denture design. It covers factors that influence design like forces in the mouth and conditions of the ridges and abutment teeth. It also discusses biomechanical principles like support, retention, bracing and stabilization. Specific principles for Kennedy class designs are outlined, including the importance of tissue coverage, indirect retention, and stress equalizing components to minimize strain. Modifications for longer edentulous spans are also noted.
Post and core restorations are used to restore endodontically treated teeth. A post is placed in the root canal to provide retention and resistance for a core. The core replaces missing coronal tooth structure. Posts can be prefabricated or custom-made from materials like metal or zirconia. Tooth preparation involves removing root canal filling, enlarging the canal, and shaping coronal tooth structure. The post and core are then cemented into place to restore the tooth.
22- OTHER FORMS OF REMOVABLE PARTIAL DENTURE.pptxAmalKaddah1
This document discusses various types of removable partial dentures and attachments. It describes unilateral removable partial dentures that extend onto the labial surface of teeth for retention. Swing-lock removable partial dentures consist of a labial bar that is hinged and locked to provide maximum retention. Overlay removable partial dentures are constructed over remaining teeth and involve preparing teeth below the gingiva. Implant-supported removable partial dentures can help improve the support, stability, and retention of distal extension dentures. The document outlines different types of attachments used for removable partial dentures including stud, magnetic, bar, and telescopic attachments.
Space maintainers are appliances used to maintain space or regain minor amounts of space lost after premature loss of primary teeth. They are classified as fixed or removable, and include band and loop appliances, lingual arches, distal shoes, and removable partial dentures. Key considerations for use of space maintainers include the time elapsed since tooth loss, dental age of the patient, and amount of bone covering unerupted permanent teeth. Space maintainers are intended to guide eruption of permanent teeth into proper positions and prevent undesirable shifting of teeth.
Other forms of removable partial denture Amal Kaddah
Prof. Amal F. Kaddah discusses various forms of removable partial dentures. This includes unilateral removable partial dentures, swing-lock removable partial dentures, overlay removable partial dentures, implant-supported removable partial dentures, attachments for removable partial dentures, and esthetic clasping partial dentures. Different attachment systems are described for use with overlay dentures including stud, magnetic, bar, and telescopic attachments. Factors such as abutment angulation and retention levels are considered for different attachment options.
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8 Surprising Reasons To Meditate 40 Minutes A Day That Can Change Your Life.pptxHolistified Wellness
We’re talking about Vedic Meditation, a form of meditation that has been around for at least 5,000 years. Back then, the people who lived in the Indus Valley, now known as India and Pakistan, practised meditation as a fundamental part of daily life. This knowledge that has given us yoga and Ayurveda, was known as Veda, hence the name Vedic. And though there are some written records, the practice has been passed down verbally from generation to generation.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of the physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar lead (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
6. Describe the flow of current around the heart during the cardiac cycle
7. Discuss the placement and polarity of the leads of electrocardiograph
8. Describe the normal electrocardiograms recorded from the limb leads and explain the physiological basis of the different records that are obtained
9. Define mean electrical vector (axis) of the heart and give the normal range
10. Define the mean QRS vector
11. Describe the axes of leads (hexagonal reference system)
12. Comprehend the vectorial analysis of the normal ECG
13. Determine the mean electrical axis of the ventricular QRS and appreciate the mean axis deviation
14. Explain the concepts of current of injury, J point, and their significance
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. Chapter 3, Cardiology Explained, https://www.ncbi.nlm.nih.gov/books/NBK2214/
7. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
- Video recording of this lecture in English language: https://youtu.be/kqbnxVAZs-0
- Video recording of this lecture in Arabic language: https://youtu.be/SINlygW1Mpc
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Cell Therapy Expansion and Challenges in Autoimmune DiseaseHealth Advances
There is increasing confidence that cell therapies will soon play a role in the treatment of autoimmune disorders, but the extent of this impact remains to be seen. Early readouts on autologous CAR-Ts in lupus are encouraging, but manufacturing and cost limitations are likely to restrict access to highly refractory patients. Allogeneic CAR-Ts have the potential to broaden access to earlier lines of treatment due to their inherent cost benefits, however they will need to demonstrate comparable or improved efficacy to established modalities.
In addition to infrastructure and capacity constraints, CAR-Ts face a very different risk-benefit dynamic in autoimmune compared to oncology, highlighting the need for tolerable therapies with low adverse event risk. CAR-NK and Treg-based therapies are also being developed in certain autoimmune disorders and may demonstrate favorable safety profiles. Several novel non-cell therapies such as bispecific antibodies, nanobodies, and RNAi drugs, may also offer future alternative competitive solutions with variable value propositions.
Widespread adoption of cell therapies will not only require strong efficacy and safety data, but also adapted pricing and access strategies. At oncology-based price points, CAR-Ts are unlikely to achieve broad market access in autoimmune disorders, with eligible patient populations that are potentially orders of magnitude greater than the number of currently addressable cancer patients. Developers have made strides towards reducing cell therapy COGS while improving manufacturing efficiency, but payors will inevitably restrict access until more sustainable pricing is achieved.
Despite these headwinds, industry leaders and investors remain confident that cell therapies are poised to address significant unmet need in patients suffering from autoimmune disorders. However, the extent of this impact on the treatment landscape remains to be seen, as the industry rapidly approaches an inflection point.
Basavarajeeyam is a Sreshta Sangraha grantha (Compiled book ), written by Neelkanta kotturu Basavaraja Virachita. It contains 25 Prakaranas, First 24 Chapters related to Rogas& 25th to Rasadravyas.
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Introdaction
Fixed partial dentures (FPDs) are "dental prostheses that are luted, screwed, or
mechanically attached or otherwise securely retained to natural teeth, tooth
roots, and/or dental implant abutments.
"' During the past decades, many types of FPDs or "bridges" have been used to
replace missing teeth. With the introduction and widespread use of
osseointegrated implants, many missing teeth are now being replaced in this
manner rather than with FPDs. Dental bridges can, of course, still be used
successfully, and this article will briefly review the many methods of bridge
construction and relate them to their applicability and current acceptance of the
practicing dentist and the treated patient.
These will include: cast-gold, stress-broken bridges; resin-bonded, etched
retainers; porcelain-fused-to-metal (PFM) bridges; and all-ceramic bridges,
including zirconia.
Principles of design
In different areas of the mouth the relative importance of these will alter. The
principles guiding the
design of the bridge are:
• Cleansability
• Appearance
• support
• Conservation of tooth tissue
PRETREATMENT ASSESSMENT
1. Biomechanics :- Bending or deflection of prosthesis varies directly with the
cube of length and inversely with the cube of the occlusogingival thickness of
connector (Fig 5). Fig 5: Deflection of a fixed dental prosthesisunder load
To minimize flexing due to long span, pontic
designs with a greater occlusogingival dimension
should be selected and biomaterial with high
yield strength (eg.Nickel –chromium) is the
material of choice to fabricate to prosthesis .
2. Arch curvature :- Pontic acts as a lever arm
when it lies outside the interabutment axis line.
It can produce a torquing movement during
occlusion, which is most common in replacing maxillary four incisors. To offset
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the lever arm a counter balancing retention is provided by including 1st premolar
as secondary abutment
3. Abutment evaluation
a. Crown root ratio - Is the measurement of the length of tooth occlusal
to the alveolar crest of the bone compare with the length of root embedded in the
bone .The crown -root ratio is evaluated from radiological findings. The optimum
ratio is 2:3 whereas 1:1 can be accepted for further treatment. Antews low » The
root surface area (pericemental area )of the abutment teeth should be more or at
least equal to the rootsuface area (pericemental area )of the missing teeth being
replace.
b. Root configuration - Configuration of roots is also an important factor.
Roots with parallel sides and developmental depressions are better able to resist
heavy occlusal forces than smooth sided conical roots. Multirooted teeth
generally provide greater stability than single rooted teeth.
c. Periodontal ligament area - Periodontal ligament area is also called
root surface area or area of periodontal ligament attachment of the root to the
bone. In 1926 Irwin H Ante presented in his paper that - the total periodontal
membrane area of the abutment teeth must be equal or exceed that of the teeth
to be replaced. So root surface area is an important parameter when long span
FPD is considered (Fig 7A & B).
4. Span length :- Longer the span of a bridge the greater will be the stress
imposed on the abutment teeth and on all components of a bridge i.e. pontics,
retainer, connectors. To prevent periodontal overloading larger number of
abutment teeth has to be selected. The components of bridge must be enough to
bear heavy occlusal stress.
5. Occlusion and Biting force :- Treatment planning and prognosis of long span
FPD also depends on amount of biting force .Amount of biting force also
depends on whether it generated by natural dentition or any prosthesis, muscular
activity, parafunctional habits etc. Excessive occlusal forces can cause loosening
of the prosthesis through flexure or can cause fracture of ceramic components or
tooth mobility.
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6. Materials:- Components (connectors, retainers, pontics) of long span FPD
should
be fabricated of materials with high yield strength to prevent flexion (eg. Nickel –
Chromium).
7. Esthetics :– In most situations FPD provides the most esthetic means of
replacing missing teeth, provided no large defect in edentulous ridge is present
8. shape of ridge :- The contour of the saddle area will be taken into account in
determining whether a bridge with a movable buccal veneer or a partial denture
should be made, or whether
surgical ridge augmentation should be considered When a bridge is to be made,
the shape of the
ridge will affect the appearance of the pontic, and if this is likely to be a critical
factor, in other words if the neck of the pontic shows and the patient is very
concerned about their appearance, then one of the procedures described below
should be followed to ensure an acceptable final result.
9. Consideration of the whole patient:- With crowns, the choice may be
between crowning a tooth or extracting it, and the decision may well be to make
a crown even though many factors, for example, the patient’s age, attitude to
treatment or oral hygiene are less than ideal. With bridges, there is often the
alternative of a partial denture, a minimum-preparation bridge or a conventional
bridge or an implant, and so it may not be necessary to make so many
compromises. If there is any doubt, it is better to make a partial denture first.
THE BRIDGE CONSISTS OF:
1. Retainer: it is the part of the bridge which is cemented to the abutment teeth
.it could be full metal, full veneer with facing, partial veneer, post crown or inlay
etc
The main types:-
Major retainer: for a conventional posterior bridge should not be less than
an MOD inlay with full occlusal protection. For anterior teeth it is usually a
complete crown.
Minor retainer: do not need full occlusal protection may be a complete or
partial crown or a two- or three-surface inlay without full occlusion protection.
Minimum preparation where the occlusion is favorable.
2.Pontic: Is the part of the bridge which represent the missing tooth and it
connected to the retainer by a connector.
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3. connector: the part of the bridge which connect the pontic and the retainer, it
maybe rigid (solid joint) or movable joint (precision attachment, key and key way)
Types of connectors: Connectors are those parts of a fixed partial denture (FPD)
or splint that join the individual retainers and pontics together.
Usually this accomplished with rigid connectors, although nonrigid connectors
are used occasionally
The latter are usually indicated when it is impossible to prepare a common path
of insertion for the abutment preparations for an FPD.
The main types
a. Rigid:- cast connectors , soldered connectors, porcelain connectors
b. non rigid :- tenon mortise connectors ,loop connectors ,split pontic
connectors ,cross pin and wing connectors
4. abutment: Is the natural tooth which support the bridge and on which the
retainer 1s cemented (tooth or root)
Types of bridges
There are 4 main type of bridges
1. fixed _ fixed bridge
2. fixed movable bridge
3.cantilever bridge
4.resin bonded bridge (conservative bridge )
Fixed _fixed bridge
In this type the pontic is attached to theretainers (mesial and distal)by rigid
connector(solid joint) so they should haveone path of insertion . This is the most
commonly used FPD
Advantages
1. maximum retention and support.
2. abutment teeth are splinted together.
3. the design is most practical for larger bridges .
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disadvantages
1.require preparation to be parallel
2. All the retainers are major retainers require extensive ,destructive preparation
of the abutment teeth.
3.Has to be cemented in one piece.
Fixed movable bridge
In this type the pontic is attached toone distal major retainer(distal end of the pontic)
by fixed connector while the other end is attached to the minorretainer (in front of
pontic )by movable joint .it s indicated in case ofdrifted abutment teeth and difficulty
to obtaining parallel abutments.
Advantages:
1. preparations do not need to be parallel to each other.
2. more conservative of tooth tissue because preparations for minor
retainers are less destructive.
3. parts can be cemented separately .
Disadvantages
1.more complicated to constructin laboratory than fixed fixed bridge .
2. difficult to make temporary bridge .
Fixed Movable partial Denture
It is defined as ,A fixed partial denture having one or more non rigid connectors ,
here a non rigid connector Is used to connect the components of the fixed partial
denture , commonly used non rigid connectors include Tenon Morti connector
(TMC), loop connector, split pontic connectors and cross pin and wing connectors
Fixed Removable Partial dentures Removable Bridges
One of the major disadvantages of long span fixed partial denture is that If one
abutment fails, the entire prosthesis has to be sacrificed , to overcome this
disadvantage. Fixed removable bridges were introduce, these dentures cannot be
removed by the patient but can be easily removed by the dentist.
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Modified Fixed Removable partial Dentures
They were developed by Andrew , hence they are also known as Andrew's bridge
systems. These denture are indicated for edentulous ridge with severe vertical
deficit, The prosthesis consists of a fixed component and a removable component
Cantilever bridge
areas of your mouth that are under less stress, such as your front teeth, a cantilever
dental bridge may be used. A cantilever dental bridge is when the “false tooth” is
only supported on one side. The result is just as aesthetic but has the benefit that
fewer teeth have to be treated.
Spring Cantilever
It is a tooth and tissue supported bridge. A pontic is supported at some distance
from the retainer . It is a type of cantilever bridge. Strong retention is required as for
all cantilever bridges and double abutments are usually necessary. The retention of
a spring bridge is severely tested when force is exerted in apicoincisal direction as
seen on biting sticky food as the retainer is subjected to detrimental stresses. To
avoid this, two retainers in adjacent teeth are used together to give added strength.
This bridge design is used while replacing anteriors with diastema or in case of
existing existiendodontically treated tooth posteriorly. This design cannot be used in
lower arch because of lack of suitable tissue support. The bar should follow the
natural contours of the rugae in the palate, so that it lies obscurely in the valleys and
its lateral margins do not represent an attraction to the tongue. The cross — section
of the bar should be a flat,oval or a rounded —T shape[8]. The model should be
lightly scraped to ensure firm seating on the soft tissue and minimize food trapping.
High platinized gold or spring metal is used. Class IV casting gold is ideal. The
Achilles heel with this design is the junction of retainerand the bar and the leverage
on the abutment.
resin bonded bridge
A resin-bonded fixed partial denture is aprosthetic construction which can replace| or
several teeth in an occlusal system and which comprises a pontic element which is
adhesively attached to 1 or more abutment teeth. To compensate for the limited
shear strength of the adhesive layer, the Jixed partial denture is occlusally supported
by the abutment(s). A direct resin-bonded fixed partial denture is made of
composite, reinforcedor not by a frame of flexible metal or fiber material. For an
indirect resin- bonded fixed partial denture, a metal, fibre-reinforced composite or
ceramic substructure is fabricated in a dental laboratory. The basic principle of a
resin-bonded fixed partial denture is minimal invasiveness. However, a restoration in
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an abutment tooth requires a certain occlusal space which is realized by tooth
preparation. Resistance preparations may be performed to improve the longevity of
resin-bonded fixed partial dentures. Both financially and biologically, a resin-bonded
bridge is a cost-effective prosthetic construction. The longevity is limited, but when
the construction fails the negative consequences for the abutments are generally
limited, which leaves open several types of other treatments.
Resin retained bridges
1. Bonded pontic
2. Rochette bridge
3. Viginia bridge
4. Maryland bridge
5. Adhesive bridge
1. Bonded pontic
Introduced by Ibsen and Portnoy in 1973, these are the earliest resin retained
prosthesis[9]. They are the resin tooth or patient’s natural tooth bonded directly to
the etched enamel. These are meant for short term replacements. The limiting factor
was the weakness of the composite resin connector.
2.Rochette bridge
CAST PERFORATED RESIN-RETAINED FPDS (MECHANICAL RETENTIO In
1973, Rochette introduced the concept of bonding metal to teeth using flared
perforations of the metal casting to provide mechanical retention. He used the
technique principally for periodontal splinting but also included pontics in his design.
Howe and Denehy recognized the metal framework's improved retention (as
compared to bonded pontics) and began using FPDS with cast-perforated metal
retainers bonded to abutment teeth and metal-ceramic pontics to replace missing
anterior teeth. Their design recommendation, extending the framework to cover a
maximum area of the lingual surface,suggested little or no tooth preparation.Patient
selection limited these FPDs to mandibular teeth or situations with an open occlusal
relationship. The restorations were bonded with a heavily filled composite resin as a
luting medium. This concept was expanded toreplacement of posterior teeth by
Livaditis. Perforated retainers were used to increase resistance and retention. The
castings were extended interproximally into the edentulous areas and onto occlusal
surfaces. The design included a defined occlusogingival path of insertion by tooth
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modification, which involved lowering the proximal and lingual height of contour of
the enamel on the abutment teeth.
These restorations were placed in normal occlusion; many have survived and have
been seen on recall for up to 13 years Despite this success, the perforation
technique presents the following limitations: e Weakening of the metal retainer by
the perforation Exposure to wear of the resin at the perforations Limited adhesion of
the metal provided by the Perforations Clinical results with the perforated technique
were followed for 15 years in a study at the University of lowa.'-' The results from this
well-controlled study suggest that for anterior fixed partial dentures, 63% of the
perforated retainer prostheses fail in about 130 months.'6 Later data'-'indicate that
50% fail in about 110 mounths
3.MARYLAND BRIDGE
ETCHED CAST RESIN-RETAINED FPDS (MICROMECHANICAL RETENTION-
"MARYLAND BRIDGE")
Based on the work of Tanaka et al" on pitting corrosion for retaining acrylic resin
facings and the metal etching studies of Dunn and Reisbick," Thompson and
Livaditis at the University of Maryland developed a technique for the electrolytic
etching of Ni-Cr and Cr-Co alloys.
Etched castm retainers have definite advantages over the castperforated
restorations:
Retention is improved because the resin-toetched metal bond can be substantially
stronger than the resin-to-etched enamel. The retainers can be thinner and still resist
flexing. The oral surface of the cast retainers is highly polished and resists plaque
accumulation. During the course of this work, the need for a composite resin with a
low film thickness for luting the casting became apparent. This led to the first
generation of resin cements, which permitted micromechanical bonding into the
undercuts in the metal casting created by etching while providing adequate strength
and allowing complete seating of the cast retainers. Comspan,* the first of these
cements, was moderately filled (60% by weight) with a film thickness of
approximately 20 um.21 Such cements are not chemically adhesive to the
metal.Electrolytic etching of base metal alloys proved to be critically dependent on
the base metal alloy and attention to detail in the laboratory. Initial etching methods
were developed for a Ni-Cr alloy* and a Ni-Cr-Mo-Al-Be alloy. These methods were
followed by simplified techniques, chemical etching, 23 or attempts at gel etching. 24
They all yield similar results, provided the technique is optimized for a specific alloy.
Proper etching requires evaluation of the alloy surface with a scanning electron
microscope. The degree of undercut created by this etching process can be seen in
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Figure 26-3. Lack of attention to detail can result in electropolishing or surface
contamination .26 With time, both severely degrade bond strengths in a moist
environment. Highly variable results were reported for dental laboratories when
etching the same alloy . Etchingand bonding techniques were adopted based on
bond strength testing of specimens only subjected to 24 hours or 7 days of water
exposure. When resin-tometal test specimens were aged for 6 monthsin water and
then thermally stressed by 10,000 or more thermal cycles, large reductions in bond
strengths were recorded. Therefore, data from specimens that have not been aged
and thermally stressed should be viewed skeptically. Even particle abrasion will
provide initially high resin-to-metal bonds, which can degrade to almost zero with
time . Well-researched and tested resin systems for direct adhesion to metal
surfaces have now completely supplanted metal etching as retention mechanisms.
4.VIRGINIA BRIDGE
MACROSCOPIC MECHANICAL RETENTION RESINRETAINED FPDS ("VIRGINIA
BRIDGE")
As a result of concerns about etching base metal and the desire to use alternative
alloys, several methods have been developed to provide visible macroscopic
mechanical undercuts on the inner surface of FPD retainers. The first was
developed at the Virginia Commonwealth University School of Dentistry and is
known as the "Virginia Bridge. It involves a "lost salt crystal" technique. On the
working cast, the abutments are coated with a model spray, and a lubricant is then
applied. Within the outlines of the retainers, specially sized salt crystals* (150 to 250
um) are sprinkled over the surface in a uniform monolayer, leaving a 0.5-mm border
without crystals at the periphery of the pattern.
This is followed by application of a resin pattern. After pattern investment, the salt
crystals are dissolved from the surface of the pattern. Adequate bond strengths are
possible with this method, but the thickness of the casting must be increased to
allow for the undercut thickness.
Although no long- term results have been reported with this technique, it does
permit the use of almost any metal-ceramic alloy An alternative technique for
macroscopic retention is the use of a cast mesh pattern on the internal surface of the
retainers. The mesh, usually made of nylon,* should be adapted to the lingual and
proximal surfaces of the abutments. The mesh is then covered by wax or resin; this
must be done carefully to prevent occluding the mesh with the pattern material.
Investing and casting then followThis method is technique sensitive but can provide
adequate retention with a resulting thick lingual casting. The cast mesh and the lost
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salt crystal method have been supplanted by direct adhesion with resin, which is
possible for most casting alloys if the correct surface treatment is provided
5. Adhesive Bridges
Inspite of electrochemical etching being very popular in America, alloy etching and
macroscopic retention is obsolete in Japan since 1980s . As a result of extensive
research chemically active adhesive cements were developed for direct bonding to
metal . These cements rely on chemical adhesion to the metal and not on
microretention in the surface of the metal for bond strength. Etching was no longer
necessary[ 19] Adhesive bridge shows chemical bonding between the metal and the
resin luting agent. Direct bonding involves the chair side and lab systems.
Metabond is first of these resin systems. It 1s based on formulation of Methylmetha
acrylate (MMA) polymer powder and MMA liquid modified with adhesion promoter 4
META (4-methacryloxyethyl trimellitate anhydride). Unique tributyl borane catalyst
1s added to liquid. On base metal alloys, Superbond has highest initial bond
strengths of any adhesive resin systems[20]. But, it gives weak bond with high gold
alloys and the bond shows hydrolytic instability. Introduction of Metabond was
followed by Panavia which can be used both with high gold ( after tin plating) and
base metal alloy. Tin plating can be done in lab, chair side or intraorally. Intraoral tin
plating 1s done by tin amide solution. Adhesive monomer used in Panavia 1s
MDP(10- methacrylolyloxydecyl dihydrogen phosphate). The phosphate end reacts
with Calcium of tooth and with the metal oxide. Bond strength to etched base metal
is greatly exceeded to that of tooth. Lab system for adhesive bonding have been
developed. Silicoater Classical ( Tiller et. al , 1984) 1s based on the need for an
intermediate layer containing silica as this provides sufficient bonding of the resin via
a silane bonding agent. New version of Silicoater MD was introduced in 1998.This
uses a special oven that burns a chrome endowing silica layer onto the surface.
Pyrosil Pen Technology (1998) is the chairside version of silicoater. Rocatec
System is a novel acrylic and metal bonding system which uses a tribochemical and
thermal embedding of a silica layer by means of sand blasting on the metal
surface[22]. Metal is thus rendered more reactive to resin via silane. [t is unfortunate
that this treatment modality 1s not very popular amongst dentist but if the case
selection 1s proper it offers outstanding conservatism with tremendous bond
strength.
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stages in the design process
Selecting abutment teeth
After the general examination of the patient and whole mouth, individual potential
abutment teeth should be examined and a note made of the presence of caries or
restorations and the extent
and quality of any restoration present. The periodontal state should be examined,
including the presence of plaque and other deposits, gingival bleeding and
periodontal pockets. The vitality and mobility of the tooth should be tested and a
periapical radiograph obtained. Usually any major problems with the individual tooth
should be dealt with first by appropriate treatment, but sometimes the more sensible
solution is to extract the tooth and replace it as an additional pontic on the bridge
rather than retain a dubious tooth as an abutment when its presence may well
jeopardize the future of the whole bridge. An example of this is where three lower
incisor teeth are already missing and the
fourth has very little bone support. The lower canines are sound and will make good
abutment teeth. They will have to be used in any case to support the bridge.
Including the remaining incisor will not add significantly to the support of the bridge
and may well detract from its long term prognosis.
A judgement must be made as to the prognosis of all the teeth in the vicinity of the
bridge and in the rest of the mouth to reduce the risk of another tooth having to be
extracted shortly after the bridge is made.
Selecting the retainers
The list of potential alternative retainers will include minimum-preparation, complete
and partial crowns retainers. The choice of a crown is inevitable when the tooth is
already heavily restored. The choice between a minimum-preparation retainer and a
crown will depend upon whether the abutment teeth have restorations in them, the
occlusal clearance and the appearance of the abutment teeth. If the only difficulty
with minimum-preparation retainers is the lack of occlusal clearance.
Selecting the pontics and connectors
The design of pontics and connectors is the responsibility of the dentist and not the
technician.
Detailed instructions should be given to the technician, particularly on the contour of
the
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ridge surface of the pontic . When the technician is unfamiliar with the dentist’s usual
requirements, the details of the design should be drawn and sent to the technician
as part of
the prescription for the bridge. Where a metal–ceramic pontic is to be made, the
dentist should indicate where the porcelain should be finished. In some cases an all-
porcelain occlusal surface is required; in others the porcelain covers only the buccal
surface and buccal cusp, leaving the remainder of the occlusal surface in metal.
Again, this should be specified.
Planning the occlusion
The first decision to be made is whether to articulate study casts and, if so, whether
it is necessary to use a simple hinge or semi-adjustable articulator. With small
bridges it is helpful to mount casts on at least a simple hinge articulator. With most
large bridges a semi-adjustable or fully adjustable articulator should be used. The
second decision is whether any occlusal adjustment is necessary prior to tooth
preparations for the bridge. With posterior bridgework it is often necessary to adjust
an over-erupted opposing tooth The anticipated occlusal relationship of the pontic
with the opposing teeth may influence the basic design of the bridge as well as the
details of the occlusal surface of the pontic; although this step is listed as the final
one in the sequence, and it is usually considered last. If the bridge design is
influenced by it, it will be necessary to introduce feedback loops to earlier stages
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Introdaction
Pontics are the artificial teeth of a partial fixed dental prosthesis (FDP) that
replace missing natural teeth, restoring function and appearance. They must
enable continued oral health and comfort. The edentulous areas where a fixed
prosthesis is to be provided maybe overlooked during the treatment-planning
phase. Unfortunately, any deficiency or potential problem that may arise during
the fabrication of a pontic is often identified only after the teeth have been
prepared or even when the definitive cast is ready to be sent to the laboratory.
Proper preparation includes a careful analysis of the definitive dimensions of the
edentulous areas: mesiodistal width, occlusocervical distance, buccolingual
dimension, and location of the residual ridge. To design a pontic that meets
hygienic requirements and prevents irritation of the residual ridge, particular
attention must be given to the form and shape of the gingival surface. Merely
replicating the form of the missing tooth or teeth is not enough. The pontic must
be carefully designed and fabricated not only to facilitate plaque control of the
tissue surface and around the adjacent abutment teeth but also to adjust to the
existing occlusal conditions. In addition to these biologic considerations, pontic
design must incorporate mechanical principles for strength and longevity, as well
as esthetic principles for satisfactory appearance of the replacement teeth
Because the pontic mechanically unifies the abutment teeth and covers a portion
of the residual ridge, it assumes a dynamic role as a component of the prosthesis
and cannot be considered a lifeless insert of gold, porcelain,
or acrylic resin.
Principles of design
Pontics are designed to serve the three main functions of a bridge:
• To restore the appearance
• To stabilize the occlusion
• To improve masticatory function.
In different areas of the mouth the relative importance of these will alter. The
principles guiding the
design of the pontic are:
• Cleansability
• Appearance
• Strength.
1. Cleansability
All surfaces of the pontic, especially the surface adjacent to the saddle, should be
made as cleansable as possible. This means that they must be smooth and
highly polished or glazed, and should not contain any junctions between different
materials. In a metal–ceramic pontic the junction between the two materials
should be well away from the ridge surface of the pontic.
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It is important too that the embrasure spaces and connectors should be smooth
and cleansable.
They should also be as easy to clean as possible. Access to them and the
patient’s dexterity should be taken into account in designing pontics. When a
conflict exists between cleansability
and appearance, priority should be given to cleansability.
2. Appearance
Where the full length of the pontic is visible, it must look as tooth-like as possible.
However, in
the premolar and first molar region it is often possible to strike a happy
compromise between a reasonable appearance for those parts of the pontic that
are visible and good access for cleaning
towards the ridge.
3. Strength
All pontics should be designed to withstand occlusal forces, but porcelain pontics
in the anterior part of the mouth may not of course be expected to withstand
accidental traumatic
forces. The longer the span, the greater the occlusal gingival thickness of the
pontic should be.
Metal–ceramic pontics are stiffer and withstand occlusal forces better if they are
made fairly thick
and if the porcelain is carried right round them from the occlusal to the ridge
surface, leaving only a line of metal visible on the lingual surface or none at all
In other word three important consideration:-
BIOLOGIC CONSIDERATIONS
The biologic principles of pontic design
pertain to the maintenance and
preservation of the residual ridge,
abutment and opposing teeth, and
supporting tissues. Factors of specific
influence are pontic-ridge contact,
amenability to oral hygiene, and the
direction of occlusal forces.
Ridge Contact
Pressure-free contact between the
pontic and the underlying tissues
prevents ulceration and inflammation
of the soft tissues.If any blanching of
the soft tissues is observed at
evaluation, the pressure area should
be identified with a disclosing medium
(e.g., pressure-indicating paste), and
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the pontic should be recontoured until tissue contact is entirely passive. This
passive contact should occur exclusively on keratinized attached tissue. When a
pontic rests on mucosa, some ulceration may appear as aresult of the normal
movement of the mucosa in contact with the pontic . Positive ridge pressure
(hyperpressure) may be caused by excessive scraping of the ridge area on the
definitive cast. This was once promoted as a way to improve the appearance of
the pontic-ridge relationship. However, because of the ulceration that inevitably
results when flossing is not meticulously performed, the concept is not
recommended unless followed as previously described for an ovate pontic.
Although ovate pontics maintain positive
tissue contact to support the pseudopapillae, healthy mucosa can be maintained
if the contact to the mucosa is tight but noncompressive and the gingival portion
of the pontic is regularly cleaned
ESTHETIC CONSIDERATIONS
No matter how well biologic and mechanical principles have been followed during
fabrication, the patient evaluates the result by how it looks, especially when anterior
teeth have been replaced. Many esthetic considerations that pertain to single crowns
also apply to pontics. Several problems unique to pontics may be encountered in the
attempt to achieve a natural appearance.
Incisogingival Length
Correctly sizing a pontic simply by duplicating the original tooth is not possible. Ridge
resorption makes such a pontic look too long in the cervical region. The height of a tooth
is immediately obvious when the patient smiles and shows the gingival margin (Fig. 20-
37). An abnormal labiolingual position or cervical contour, however, is not immediately
obvious. This fact can be used to produce a pontic of good appearance by recontouring
the gingival half of the labial surface (see Fig. 20-36). The observer sees a normal tooth
length but is unaware of the abnormal labial contour. The illusion is successful.
Even with moderately severe bone resorption, obtaining a natural appearance by
exaggerated contouring of the pontics may still be possible. In areas where tooth
loss is accompanied by excessive loss of alveolar bone, however, a pontic of normal
length would not touch the ridge at all. One solution is to shape the pontic to simulate a
normal crown and root with emphasis on the cementoenamel junction. The root can be
stained to simulate exposed dentin (Fig. 20-38). Another approach is to use pink
porcelain to simulate the gingival tissues (Fig. 20-39). However, such pontics then have
considerably increased tissue contact and require scrupulous plaque control for long-
term success. Ridge augmentation procedures have been successful in correcting areas
of limited resorption. When bone loss is severe, the esthetic result obtained with a partial
removable dental prosthesis is often better than that obtained with an FDP
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Mesiodistal Width
Frequently, the space available for a pontic is greater or smaller than the width of the
contralateral tooth. This is usually because of uncontrolled tooth movement that
occurred when a tooth was removed and not replaced. If possible, such a discrepancy
should be corrected by orthodontic treatment. If this is not possible, an acceptable
appearance may be obtained by incorporating visual perception principles into the pontic
design. In the same way that the brain can be confused into misinterpreting the relative
sizes of shapes or lines because of an erroneous interpretation of perspective, a pontic
of abnormal size may be designed to give the illusion of being a more natural size. The
width of an anterior tooth is usually identified by the relative positions of the mesiofacial
and distofacial line angles, and the overall shape by the detailed pattern of surface
contour and light reflection between these line angles. The features of the contralateral
tooth (Fig. 20-41) should be duplicated as precisely as possible in the pontic, and the
space shape of the proximal areas. The retainers and the pontics can be proportioned to
minimize the discrepancy. (This is another situation in which a diagnostic waxing
procedure helps solve a challenging restorative problem.) Space discrepancy presents
less of a problem when posterior teeth are being replaced (Fig. 20-42) because their
distal halves are not normally visible from the front. A discrepancy here can be managed
by duplicating the visible mesial half of the tooth and adjusting the size of the distal half.
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The Gingival Interface
An esthetically successful pontic replicates the form, contours, incisal edge,
gingival and incisal embrasures, and color of adjacent teeth. The pontic’s
simulation of a natural tooth is most often betrayed at the tissue-pontic junction.
The greatest challenge in this situation is to compensate for anatomic changes
that occur after extraction. To achieve a “natural” appearance, special attention
should be paid to the contour of the labial surface as it approaches the tissue-
pontic junction. This cannot be accomplished by merely duplication of the facial
contour of the missing tooth; after a tooth is removed, the alveolar bone
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undergoes resorption or remodeling, or both. If the original tooth contour were
followed, the pontic would look unnaturally long incisogingivally . For an esthetic
pontic to achieve the illusion of a natural tooth, observers must think that they are
seeing a natural tooth. The modified ridge-lap pontic is recommended for
most anterior situations; it compensates for lost buccolingual width in the residual
ridge by overlapping what remains. Rather than emerging from the crest of the
ridge as a natural tooth would, the cervical aspect of the pontic sits in front of the
ridge, covering any abnormal ridge structure that results from tooth loss.
Fortunately, because most teeth are viewed from only two dimensions, this
relationship remains undetected. A properly designed, modified ridge-lap pontic
provides the required convexity on the tissue side, with smooth and open
embrasures on the lingual side for ease of cleaning. This is difficult to
accomplish. Clinically, many pontics have suboptimal contour, which results in an
unnatural appearance. This can be avoided with careful preparation at the
diagnostic waxing stage . Sometimes the ridge tissue must be surgically
reshaped to enhance the result. In normal situations, light falls from above, and
an object’s shadow is below it. Unexpected lighting or unexpectedly positioned
shadows can be confusing to the brain. Because of past experience, the brain
“knows” that a tooth grows out of the gingiva, and it therefore “sees” a pontic as a
tooth unless telltale shadows suggest otherwise. The dentist must carefully study
where shadows fall around natural teeth, particularly around the gingival margin.
If a pontic is poorly adapted to the residual ridge, there is an unnatural shadow in
the cervical area that looks odd and spoils the illusion of a natural tooth. In
addition, recesses at the pontic-gingival interface collect food debris, further
ruining the illusion of a natural tooth. When appearance is of utmost concern, the
ovate pontic, used in conjunction with alveolar preservation or soft tissue ridge
augmentation, can provide an appearance at the gingival interface that is virtually
indistinguishable from that of a natural tooth. Because it emerges from a soft
tissue recess, this pontic is not susceptible to many of the esthetic pitfalls
applicable to the modified ridge-lap pontic. However, in most circumstances,
the patient must be willing to undergo the additional surgical procedures that are
necessary for placement of an ovate pontic
.
MECHANICAL CONSIDERATIONS
The prognosis of FDP pontics is compromised if mechanical principles are not followed
closely. Mechanical problems may be caused by improper choice of materials, poor
framework design, poor tooth preparation, or poor occlusion. These factors can lead to
fracture of the prosthesis or displacement of the retainers. Long-span posterior FDPs are
particularly susceptible to mechanical problems. Inevitably, significant flexing occurs as a
result of high occlusal forces and because the displacement effects increase with the
cube of the span length. Therefore, evaluating the likely forces on a pontic and designing
accordingly are important. For example, a strong all-metal pontic, rather than a metal-
ceramic pontic, may be needed in high-stress situations, in which it would be more
susceptible to fracture. When metal-ceramic pontics are chosen, extending porcelain
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onto the occlusal surfaces to achieve better esthetics should also be carefully evaluated.
In addition to its potential for fracture, porcelain may abrade the opposing dentition if the
occlusal contacts are on enamel or metal.
PRETREATMENT ASSESSMENT
Certain procedures enhance the success of an FDP. In the treatment-planning
phase, diagnostic casts and waxing procedures may prove especially valuable for
determining optimal pontic design:-
Pontic Space
One function of an FDP is to prevent tilting or drifting of the adjacent teeth into
the edentulous space. If such movement has already occurred, the space
available for the pontic may be reduced and its fabrication complicated.
In such circumstances, creating an acceptable appearance without orthodontic
repositioning of the abutment teeth is often impossible, particularly if esthetic
appearance is important. (Modification of abutments with complete-coverage
retainers is sometimes feasible.) Careful diagnostic waxing procedures help
determine the most appropriate treatment. Even with a lesser esthetic
requirement, as for posterior teeth, overly small pontics are unacceptable
because they trap food and are difficult to clean. When orthodontic repositioning
is not possible, increasing the proximal contours of adjacent teeth may be better
than making an FDP with undersized pontics. If there is no functional or esthetic
deficit, the space can be maintained without prosthodontic intervention.
Residual Ridge Contour
The edentulous ridge’s contour and topography should be carefully evaluated
during the treatment-planning phase. An ideally shaped ridge has a smooth,
regular surface of attached gingiva, which facilitates maintenance of a plaque-
free environment. Its height and width should allow placement of a pontic that
appears to emerge from the ridge and mimics the appearance of the neighboring
teeth. Facially, it must be free of frenum attachment and be of adequate facial
height to sustain the appearance of interdental papillae.
Siebert classified residual ridge deformities into three categories:-
• Class I defects: faciolingual loss of tissue width with normal ridge height
• Class II defects: loss of ridge height with normal ridge width
• Class III defects: a combination of loss in both dimensions
Loss of residual ridge contour may lead to unaesthetic open gingival embrasures
food impaction and percolation of saliva during speech.
Surgical Modification
Although residual ridge width may be augmented with hard tissue grafts, this is
usually not indicated unless the edentulous site is to receive an implant
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Gingival Architecture Preservation
By conditioning the extraction site and providing a matrix for healing, the dentist
can preserve the preextraction gingival architecture, or “socket.” Preparing the
abutment teeth before the extraction is the preferred technique. An interim FDP
can be fabricated indirectly, ready for immediate insertion. Because socket
preservation is dependent on underlying bone contour, the extraction of the tooth
to be replaced should be atraumatic, with the aim of preserving the facial plate
of bone. The scalloped architecture of interproximal bone forming the extraction
site is essential for proper papilla form, as are facial bone levels in the prevention
of alveolar collapse. If bone levels are compromised before or during extraction,
the sockets can be grafted with an allograft material (hydroxyapatite, tricalcium
phosphate, or freeze-dried bone).
The surfaces of a pontic
A pontic has five surfaces:
• The ridge
• The occlusal
• The approximal
• The buccal or labial
• The lingual or palatal.
Some of these will be similar to the natural tooth
being replaced; others will be very different.
The ridge surface
This surface of the pontic is the most difficult to
clean, and yet it also has a considerable influence
on appearance. The basic designs of
ridge surface (box 20-1).
1. Sanitary or Hygienic Pontic
As its name implies, the primary design feature of the sanitary pontic allows easy
cleaning because its tissue surface remains clear of the residual ridge (Fig. 20-
13, A). This hygienic design enables easier plaque control by allowing gauze
strips and other cleaning devices to be passed under the pontic and seesawed in
a shoeshine manner. Disadvantages include entrapment of food particles, which
may lead to tongue habits that annoy the patient. The hygienic pontic is the least
tooth like design and is therefore reserved for teeth seldom displayed during
function (i.e., the mandibular molars). A modified version of the sanitary pontic
has been developed (see Fig. 20-13, B and C). Its gingival portion is shaped like
an archway between the retainers. This geometry allows for increased connector
size and a decrease in the stress concentrated in the pontic and connectors.It is
also less susceptible to tissue proliferation that can occur when a pontic is too
close to the residual ridge (see Fig. 20-13, D).
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2. Saddle and Ridge-Lap Pontics
The saddle pontic has a concave fitting surface that overlaps the residual ridge
buccolingually, simulating the contours and emergence profile of the missing
tooth on both sides of the residual ridge. However, saddle or ridge-lap designs
should be avoided because the concave gingival surface of the pontic is not
accessible to cleaning with dental floss, which leads to plaque accumulation. This
design deficiency has been shown to result in tissue inflammation.
(a) A classic saddle or ridge lap pontic.
(b) A linguogingival ridge
(arrow) or extension past the crest of
the ridge, although less severe, still
constitutes a saddle
3. Modified Ridge-Lap Pontic
The modified ridge-lap pontic combines the best features of the hygienic and
saddle pontic designs, combining esthetics with easy cleaning. demonstrate how
the modified ridge-lap pontic overlaps the residual ridge on the facial side (to
achieve the appearance of a tooth emerging from the gingiva) but remains
clear of the ridge on the lingual side. To enable optimal plaque control, the
gingival surface must have no depression or hollow; rather, it should be as
convex as possible from mesial to distal aspects (the greater the convexity,
the easier the oral hygiene). Tissue contact should resemble a letter T whose
vertical arm ends at the crest of the ridge. Facial ridge adaptation is essential for
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a natural appearance. Although this design was historically referred to as ridge-
lap design, the term ridgelap is now used synonymously with saddle design The
modified ridge-lap design is the most common pontic form used in areas of the
mouth that are visible during function (maxillary and mandibular anterior teeth
and maxillary premolars and first molars).
4. Conical Pontic
Often called egg-shaped, bullet-shaped, or heart-shaped, the conical pontic is
easy for the patient to keep clean. It should be made as convex as possible and
should have only one point of contact: at the center of the residual ridge. This
design is recommended for the replacement of mandibular posterior teeth, for
which esthetic appearance is a lesser concern. The facial and lingual contours
are dependent on the width of the residual ridge; a knife-edged residual ridge
necessitates flatter contours with a narrow tissue contact area. This type of
design may be unsuitable for broad residual ridges because the emergence
profile associated with the small tissue contact point may create areas of food
entrapment . The sanitary or hygienic pontic is the design of choice in these
clinical situations.
Conical pontic used correctly with a thin
ridge (a) and incorrectly with a broad,
flat ridge (b). The arrows indicate
debris-trapping embrasure spaces.
5. Ovate pontic
The ovate pontic is a round-end design currently in use where esthetics is a
primary concern. Its antecedent was the porcelain root-tipped pontic, which was
used considerably before 1930 as an esthetic and sanitary substitute for the
saddle pontic. The tissue-contacting segment of the ovate pontic is bluntly
rounded, and it is set into a concavity in the ridge. It is easily flossed. The
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concavity can be created by placement of a provisional fixed partial denture with
the pontic extending one-quarter of the way into the socket immediately after
extraction of the tooth. It also can be created surgically at some later time. This
pontic works well with a broad, flat ridge, giving the appearance that it is growing
from the ridge.
The round-end ovate pontic fits into a
depression in the ridge.
The occlusal surface
The occlusal surface of the pontic should resemble the occlusal surface of the
tooth it replaces. Otherwise it will not serve the same occlusal functions and may
not provide sufficient contacts to stabilize the occlusal relationships of its
opponents. In some cases, when occlusal stability is less important (for example
when the pontic is opposed by another bridge), the pontic may be made narrower
bucco-lingually to improve access for cleaning. Other arguments for narrowing
pontics are less convincing .
Occlusal Forces
Reducing the buccolingual width of the pontic by as much as 30% has been
suggested as a way to lessen occlusal forces on, and thus the loading of,
abutment teeth. This practice continues today, although it has little scientific
basis. Critical analysis has revealed that forces are lessened only when food of
uniform consistency is chewed and that a mere 12% increase in chewing
efficiency can be expected from a one-third reduction of pontic width. Potentially
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harmful forces are more likely to be encountered if an FDP is loaded by the
accidental biting on a hard object or by parafunctional activities such as bruxism,
rather than by chewing of foods of uniform consistency. Narrowing the occlusal
surface does not reduce these forces. In fact, narrowing the occlusal surface may
actually impede or even preclude the development of a harmonious and stable
occlusal relationship. Like a malposed tooth, it may cause difficulties in plaque
control and may not provide proper cheek support. For these reasons, pontics
with normal occlusal widths (at least in the occlusal third) are generally
recommended. One exception is the situation in which the residual alveolar ridge
has collapsed buccolingually. Reducing pontic width may then be desired and
would thereby lessen the lingual contour and facilitate plaque-control measures.
The approximal surfaces
The shape of the mesial and distal surfaces of the pontic will depend upon the
design. With fixed–fixed bridges the approximal surface will consist partly of a
fixed connector. It is important that the embrasure space between the connector
and the gingival tissue be as open as possible to ensure that there is good
access for cleaning, particularly if the pontic is a ridge-lap or saddle pontic
(Figure 9.7). The gingival side of a movable joint is more difficult to leave entirely
smooth, and so it is again important that there should be good access for
cleaning. A balance has to be achieved to ensure that there is adequate
metal present to provide sufficient strength and rigidity for the connector as well
as allowing open embrasures for cleaning. The approximal surface of a cantilever
bridge on its free side will simply make normal contact with the adjacent tooth, or
in some cases there may be a diastema with no contact. Occasionally, where the
span is very short, a cantilever pontic may be made to overlap the adjacent tooth
to improve its appearance. In this case the pontic surface in contact with the
natural tooth should be as smooth as possible, although it may be slightly
concave. If the patient is taught to clean with dental floss, the natural tooth
surface should not be any more susceptible to caries than with a normal contact
point.
Figure 9.7 Well-contoured open embrasure spaces.
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The buccal and lingual surfaces
The buccal surface of a wash-through or domeshaped pontic does not resemble
the shape of a natural buccal surface, particularly gingivally. With ridge-lap and
saddle pontics the buccal surface is intended to look as much like a tooth as
possible for its entire length. The problem is that when a tooth is missing, so also
is some of the alveolar bone that supported it. This means that the alveolar
contour where the pontic touches the ridge never looks entirely natural, and the
pontic must also be shaped unnaturally to meet the resorbed ridge. The
aesthetic result is not good and there is greater difficulty than necessary in
cleaning. No ridge–pontic relationship can ever appear entirely natural, even
when the ridge has not resorbed significantly or where it has been augmented –
see Figure 7.9. But at the normal distance from which teeth are seen, the illusion
that the tooth emerges from the gum can be sufficiently convincing. The lingual
surface of a pontic will be designed as a result of deciding the ridge surface. With
ridge-lap pontics, the lingual surface should be smooth and convex.
Post-insertion Hygiene
The mesial, distal, and lingual gingival embrasures of the pontic should be
wide open to allow the patient easy access for cleaning, and the contact between
pontic and tissue must allow the passage of floss from one retainer to the other.
After the fixed partial denture is cemented, the patient should be taught
appropriate technique(s) that can be mastered. The individual should be
motivated to practice good hygiene around and under the pontic with dental floss,
interproximal brushes, or pipe cleaners. The method used will depend on
embrasure size, accessibility, and patient skill. The patient should be given time
to learn the techniques and demonstrate the ability to clean the underside of the
pontic and the adjacent areas of the abutment teeth. Home care is evaluated at
each appointment, and the necessity for good hygiene and the skills to
accomplish it are reinforced. Even the smoothest pontic surface must be cleaned
well and often to prevent the accumulation of plaque. If cleaning is not done at
frequent, regular intervals, the tissue around the pontic will become inflamed.
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Pontic Materials
Some FDPs are fabricated entirely of metal, porcelain, metal-ceramic, or acrylic
resin, but most consist of a combination of metal and porcelain. The acceptance
of acrylic resin–veneered pontics has been limited because of their reduced
durability (wear and discoloration). The newer indirect composites, which are
based on high inorganic content–filled resins and fiber-reinforced materials, have
revived interest in composite resin and resinveneered pontics.
Fiber-Reinforced Composite Resin
Pontics Composite resins can be used in partial FDPs without a metal
substructure. A substructure matrix of impregnated glass or polymer fiber
provides structural strength. Because of the physical properties of this system,
combined with its excellent marginal adaptation and esthetics, it is a possible
metal-free alternative for FDPs, although long-term clinical performance is not yet
known
Prefabricated pontic facings
Historically, preformed porcelain facings were popular for fabricating pontics.
They required adaptation to a specific edentulous space, after which they were
reglazed. Some, such as Trupontics, Sanitary Pontics, and Steele’s Facings
(Franklin Dental), relied on a lug in a custom cast metal backing to engage a slot
contraindication
Indication
Disadvantges
Advantages
Materail
Long spans with
high stress
Most
situations
Difficult to fabricate if
an an abutment is not
metal ceramic
Weaker than all metal
Nonesthetic
Esthetics
Biocompatible
Metal
ceramic
Where esthetics
is imprtomant
Mandibular
molars,
especially
under high
occlusal force
Nonesthetic
Strength
Straightforward
Procedure
All metal
Long span with
high stress
High esthetic
demand
Risk of fracture
Unable to sectioned
and reconnected
Large connectors
needed
Best esthetics
Biocompatible
All ceramic
Definitive
restorations
Long term
provisional
Poor abrasion
resistance
Staining at resin metal
interface
Permeable to oral
fluids
Straightforward
procedure
Resin
veneered
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in the occlusal or lingual surface of the facing. The large bulk of porcelain could
result in a thin gold backing susceptible to flexing. Harmony (Harmony Dental)
and Trubyte (Dentsply) facings used horizontal pins that fit into the gold backing.
They were difficult to use in patients with limited occluso-gingival space, and
refitting the pins into a backing after casting was demanding. Porcelain denture
teeth also were modified to use as pontic facings. Multiple pinholes 2.0 mm deep
were made with a drill press in the lingual surface of the reverse pin facing. The
pins protruded from the backing, providing retention where a deep overbite would
have over shortened conventional pins. Unfortunately, the pinholes in the facing
were stress points that led to fracture.
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Reference
Planning and making crowns and bridges Fourth Edition(2007)
Bernard G N Smith & Leslie C Howe.
CONTEMPORARY FIXED PROSTHODONTICS FIFTH
EDITION(2016) Stephen F. Rosenstiel , Martin F. Land, and Junhei
Fujimoto.
Fundamentals of Fixed Prosthodontics, 4ed (2012) , Herbert T.
Shillingburg, Jr, DDS et al .
Long Span Fixed Partial Denture - A Review Article , Asish Kumar
Barui et al , Maven 2019, www.idahowrah.org.