Resin-bonded fixed partial dentures are fixed partial dentures that are cemented onto abutment teeth using resin. There are different types based on the technique used to finish the tissue surface, including Rochette bridges, Maryland bridges, cast mesh bridges, and Virginia bridges. Maryland bridges use electrolytic or chemical etching to create microscopic porosities on the metal retainer for mechanical bonding with resin. Fabrication involves preparing abutment teeth, making a provisional restoration, designing the prosthesis based on whether it replaces anterior or posterior teeth, and bonding the metal retainer to teeth using either mechanical interlocking/etching or chemical bonding like etching or tin-plating.
Resin retained fpd/ oral surgery courses / 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.
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.
Resin retained fpd/ oral surgery courses / 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.
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.
By definition, a veneer is a small sheath-like cover that conceals a particular entity. In dentistry, a veneer is a small piece of porcelain or composite material that fits over a tooth’s enamel, covering teeth abnormalities for a beautiful smile.
Here we discuss various types of veneers, their uses , preparation types as well as the recent advances in a phased manner.
Resin bonded bridges/certified fixed orthodontic courses by Indian dental aca...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.for more details please visit
www.indiandentalacademy.com
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
principles of tooth preparation - ann george final.pptxDrHIMANSHUTIWARI1
No recent literature has reviewed the current scientific knowledge on complete coverage tooth preparations.Nine scientific principles have been developed that ensure mechanical, biologic, and esthetic success for tooth preparation of complete coverage restorations.
INTRODUCTION- Removable partial denture: the replacement of missing teeth and supporting tissues with a prosthesis designed to be removed by the wearer-GPT.
Cast partial denture is a type of partial denture comprising a cast metal framework with acrylic resin prosthetic teeth.
Traditional acrylic partial dentures are less durable, retentive, and stronger than cast partial dentures.
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
By definition, a veneer is a small sheath-like cover that conceals a particular entity. In dentistry, a veneer is a small piece of porcelain or composite material that fits over a tooth’s enamel, covering teeth abnormalities for a beautiful smile.
Here we discuss various types of veneers, their uses , preparation types as well as the recent advances in a phased manner.
Resin bonded bridges/certified fixed orthodontic courses by Indian dental aca...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.for more details please visit
www.indiandentalacademy.com
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
principles of tooth preparation - ann george final.pptxDrHIMANSHUTIWARI1
No recent literature has reviewed the current scientific knowledge on complete coverage tooth preparations.Nine scientific principles have been developed that ensure mechanical, biologic, and esthetic success for tooth preparation of complete coverage restorations.
INTRODUCTION- Removable partial denture: the replacement of missing teeth and supporting tissues with a prosthesis designed to be removed by the wearer-GPT.
Cast partial denture is a type of partial denture comprising a cast metal framework with acrylic resin prosthetic teeth.
Traditional acrylic partial dentures are less durable, retentive, and stronger than cast partial dentures.
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
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Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
3. ● As the name implies, these are fixed partial dentures,
which are cemented onto the abutments using special
resins.
● Composite resin bonded/retained fixed partial dentures
were developed from noninvasive, micro-retentive
techniques used in restorative dentistry."
10. ● one or more pontics supported by thin metal retainers
placed only on the lingual and/or proximal surface of
the abutments.
● Retention in these prostheses relies on the adhesive
bonding between etched enamel and the metal casting
(retainer).
11. ● They are held in place by resin, which locks
mechanically into:
a. The microscopic undercuts present on etched
enamel
b. Undercuts present in the casting.
11
12. Indications
● Retainers of fixed partial dentures for abutments with
sufficient enamel to etch for retention.
● Splinting of periodontally compromised teeth.
● Stabilizing dentitions after orthodontics (permanent
● retainers).
● Medically compromised, indiligent and adolescent pati-
ents who cannot cooperate with long sessions of
therapy.
13. Contraindications
● Patients with an acknowledged sensitivity to base metal
alloys (NI),
● When the labial aesthetics of abutments require
improvenment.
● Insufficient occlusal clearance to provide 2 to 3 mm
● vertical frictional retention in the axial walls. E.g.
abraded teeth
14. ● Deep vertical overbite.
● Inadequate enamel surfaces to bond. E.g.
extensive caries, existing restorations.
● Incisors with extremely thin faciolingual
dimensions.
14
15. Advantages
● Noninvasive to dentin with lingual and proximal tooth
preparation including occlusal rests.
● Decreased pulpal Irritation
● Conservative with undeniable patient appeal/comfort.
● Decreased tissue irritation due to the placement of
supragingival margins"
● Does not require cast alterations or removable die
preparation.
● Reduced cost with less chair time.
16. Disadvantages
● Criteria for choosing the patient are not discrete.
● Demanding technique and tooth preparation- Even
minor laboratory errors cannot be corrected easily.
● Plaque accumulation may occur because design is
outside the dimensions of the natural tooth.
● Bulky contours may be intolerable in some patients.
Patient expectations of esthetics are high but routine
results are not outstanding
● Not ideal for replacing more than one tooth.
● Graying of the incisal surfaces especially in labio
lingually thin teeth,
17. Types of Resin-bonded Fixed Partial
Dentures
Based on the technique used to finish the tissue surfaca
resin-bonded fixed partial denture can be classified as:
● Rochette bridge
● Maryland bridge
● Cast mesh fixed partial dentures
● Virginia bridge
18. Rochette Bridge
● Rochette was the first to design a resin-bonded
prosthesis (1973)
● He used wing like retainers with funnel shaped
perforations with the base towards the tooth surface
19. ● He also used silane-coupling agents for
additional retention.
● This was one of the most widely accepted
designs
● Etched retainers coated with pyrolyzed silane
showed up to 47% superior retention.
19
20. ● The major disadvantage of Rochette Bridge is that the
resin exposed through the metal perforations is subjected
to external stress, abrasion and marginal leakage.
20
21. Maryland Bridges
● Many scientists developed different designs to overcome
the shortcomings of Rochette bridges;
● Dunn and Reisbick used electrochemical pit corrosion to
study ceramic bonding to base metals
● Tanaka et al. studied the retention of acrylic resin on
metal copings.
23. ● Finally, Livaditis and Thompson from University of
Maryland School of dentistry used Dunn's study and
developed Maryland bridges
24. ● Here mechanical retention was developed by the micro
porosities present on the tissue surface of the retainer.
● Micro-porosities are created by etching the tissue
surface of the retainer
25. ● Etching Technique
● The suggested etching techniques that can be employed
while fabricating Maryland bridges can be broadly
divided into:
1.ELECTROCHEMICAL ETCHING.
2.NONELECTROCHEMICAL ETCHING.
26. Electrochemical etching:
● Here etching is done using a chemical electrolyte in the
presence of an electrical gradient.
● Before etching, the retainer is coated using paraffin wax.
● The Wax should cover the entire retainer except for the
area to be etched.
27. ● For non-Beryllium Nickel Chromium alloys: Etching is
done in two stages.
In the first stage, the retainer is immersed in 3.5% nitric acid
unders a current of 250 mA for 5 minutes.
Next the retainer is cleaned by immersing it in 18% HCl in an
ultrasonic cleaner for 10 minutes
28. ● For Beryllium containing Nickel Chromium alloys: It is
also a two-step technique.
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30. Disadvantages is electrochemical etching:
● Expensive.
● Very sensitive technique.
● Tedious procedure, difficult to Control the area to be
etched
31. Non-electrochemical Etching:
● Commonly used nonelectro chemical etching techniques
include:
● Livaditis proposed a technique wherein Nickel-Chromium
Beryllium alloys were successfully etched In an etching
solution placed in a water bath for one hour at 70 Degree
Celsius
32. Advantages of nonelectrochemical
etching
● Does not require special equipments.
● Etching is comparable to more expensive techniques.
● The prosthesis can be fabricated and bonded in two
stages.
33. Cast Mesh Fixed Partial Denture
● Here a nylon mesh
is placed on the
tissue surface of
the retainer wax
pattern.
● The nylon mesh is
placed on the cast
before fabricating
the wax pattern.
● These retainers do
not require acid
etching
34. Drawbacks of this design include:
● The nylon mesh may not adapt well to the cast during
pattern fabrication
● The wax may flow in between the mesh locking all the
undercuts.
35. Virginia Bridges
● These are resin bonded fixed partial dentures which use
particle roughened retainers.
● 1hey were proposed by Moon and Hudgins.
36. ● The retainer wax patterns are fabricated using resin.
● 150-250 um salt crystals are sprinkled on the cast prior
to resin fabrication.
● The salt crystals get incorporated onto the tissue
surface of the resin patten. The salt crystals are
dissolved and the resin pattern is invested and cast.
37. ● Dissolved crystals will produce voids in the
resin pattern ('Lost salt technique").
● These voids will also be reproduced in the cast
metal retainer and they help in mechanical
retention
39. ● No surface treatment of the retainer is necessary.
● Air abrasion with aluminum oxide is sufficient.
● Tanaka et al. proposed few techniques to improve the
bonding of these dentures:He suggested the immersion
of the retainer in sulfuric acid for proper oxide layer
formation.
40. ● For noble metal alloys, he suggested inducing
a heat accumulated copper oxide deposition.
This gives the necessary oxide layer.
● He also proved that air abrasion with
aluminum oxide aids to improve retention.
41. Advantages
● Even noble metal alloys can be used.
● Surface treatment of the retainer is not
necessary.
42. Steps in the Fabrication of a
Resin-bonded Fixed Partial Denture
The steps in the fabrication of a resin-bonded fixed partial
denture can be grouped into three major categories.
..predominantly in relation to Maryland bridges.
● Preparation of abutment teeth.
● Fabricating the provisional restoration.
43. Preparation of Abutment Teeth
common principle are followed during tooth preparation.
● Single path of insertion.
● Proximal undercuts must be removed.
● Rest seats should provide good resistance form
● (posterior teeth only)
● The prepared area should have definite and distinct
margins.
44. Principles of Tooth Preparation
● The margins of the prepared area should be at least
1mm away from the incisal/occlusal edge, and 1 mm
away from the gingival margin
● Definitive lingual ledges should be formed during tooth
preparation.
● This will help to provide resistance form for the retainer,
and assist in positive (proper) seating during
cementation.
45. ● Sometimes, the preparation can be extended more than
180° of the tooth circumference in order to enhance
retention
● Marginal fit is important for resin-retained restoration
just as for conventional fixed partial denture.
46. Fabricating the Provisional Restoration
● An accurate impression should be made of the prepared
tooth.
● It is vital for the impression to reproduce the small
preparation done on the tooth.
47. ● After impression making, a provisional restoration made
of auto-polymerizing acrylic resin should be fabricated
and inserted.
Preparing a provisional restoration for such cases poses
certain challenges, namely:
● -It is difficult to achieve good retention with minimal
tooth preparation.
48. ● Sometimes, a removable appliance may be sufficient, but
the provisional restoration should stabilize the
abutments.
● Significant and rapid tilting or supra eruption of the
abutment teeth can occur, particularly in younger
patients.
50. Design of a Resin Bonded Prosthesis
● The design of the prosthesis varies for anterior and
posterior teeth replacements.
● Hence, we shall discuss about the design of anterior and
posterior replacement separately.
51. Design of Anterior Resin
● For an anterior prosthesis, enamel preparation should
extend over the largest possible area, without
compromising aesthetics.
● If a single anterior tooth is to be replaced, the retainers
(wings) should extend over at least one tooth on either
side of the edentulous space.
● If two teeth are being replaced, the retention wing
should extend over two teeth on either side (double
abutments).
52. ● Design considerations for an anterior resin
bonded fixed partial denture: The following
design concepts should be considered while
designing an anterior resin bonded fixed
partial denture.
53. ● Sufficient lingual clearance about 0.6-0.8 mm (1.0 mm is
optimal), should be provided for occlusion.475
● A cingulum rest seat should be prepared. This acts like a
vertical stop against occlusal forces
A single path of insertion should be created (usually in
the incisogingival direction along the proximal surface
54. ● There should be an identifiable supragingival finish lin e
about 1 mm above the crest of tissue
● An additional 0.2 mm relief should be provided to
accommodate protrusive movements of the mandible
55. ● Two plane proximal facial extensions without metal
display
● may be provided for additional retention
56. Principles of Posterior Tooth Preparation
● Posterior tooth preparation consists of preparing three
major components namely:
● The occlusal rest (for resistance to gingival
displacement)
● Lingual segment of the proximal reduction done using a
flat end tapered diamond.
● The retentive surface (for resistance to occlusal dis-
placement)
● The proximal wrap (for resistance to torquing forces).
57. ● Occlusal Rest Seat
● It should be spoon-shaped and placed on the proximal
marginal of the abutment adjacent to the edentulous
area
● Any design modification, which is incorporated into the
prosthesis, should be harmonious with the
predetermined path of insertion.
58. Design of a Posterior Resin-bonded
● Posterior resin-bonded fixed partial dentures should be
designed to withstand more occlusal forces. Here,
aesthetics is not a major concern
59. ● Retentive Surface
● Proximal and lingual axial walls should be reduced to
move their height of contour more cervically
● The height of contour should be about 1 mm above the
crest of the free gingiva.
● Knife-edge type of margin is recommended.
60. ● Proximal Wrap
● The alloy framework should be designed to engage
atleast 180 degrees of tooth structure when viewed from
the occlusal surface.
61. ● Bonding of Resin-bonded
● Fixed Partial Dentures
● As the name implies, an adhesive resin is used to cement
a metal retainer onto the abutment.
● The type of bonding that exists between the metal and
the resin can be either mechanical or chemical in nature.
62. ● In the original design, Rochette made six perforations on
the retainer using a warming instrument.
● This provides mechanical undercuts for the resin cement.
● The major disadvantage of the Rochette's perforated
design is that the resin is exposed to the oral fluids,
which may lead to abrasion of the resin or microleakage
at the resin-metal interface.
63
63. ● Mechanical bonding of resin
● Retention obtained from mechanical bonding
can be either macroscopic or microscopic in
nature.
● Macroscopic retention is by mechanical
interlocking (Rochette's perforated design),
● Microscoplc retentlon is by electrolytie etching
64
64. ● Microscopic retention or Electrolytic etching
● In this procedure, microscopic porosities are created on
the tissue surface of the nickel chromium framework by
differential electrolytic etching.
● The fabrication technique was developed at the
University of Maryland School of Dentistry and the
prosthesis is sometimes referred to as the 'Maryland
Bridge
65
65. ● Procedure
● Wax pattern of the framework Is fabricated and cast
using nickel-chromium metal-ceramic alloy.
● Different alloys require different etching procedures.
● It is important to use an alloy that has been well tested.
● The pontic is fabricated using porcelain in the
conventional manner.
66
66. ● The pontic is glazed and stained after try-In.
● The tissue surface of the prosthesis should be sand
blasted using aluminum oxide.
67
67. ● The next step involves acid etching the tissue surface of
the retainers.
● Acid etching is done by immersing the metal retainer in
an acid.
● The areas that have to be protected are coated with
paraffin wax.
68
68. ● After blocking out the external surface of the retainer
with wax, the prosthesis should be attached to an
electrolytic etching unit
69
69. ● A typical cycle consists of 3 minute immersion in 109%
HSO, under a current of 300 nmilliamps per square (other
etching cycles were discussed before).
● Next the etched surface should be cleaned ultrasonically
in 189% HCl and then washed and air dried.
70
70. ● The etched surface must not be handled (touched) after
this stage
71
71. ● Macroscopic retention
● This can either be done by Rochette's method of per
foration or by fabricating the pattern with macroscoplc
surface porosities.
● We have already described Rochette's design previously.
● Hence in the following section, we will discuss only about
creating macroscopic porosities
72
72. ● Creating macroscopic porosities: This can be done by two
● methods discussed below. The advantage of both these
techniques is that any alloy can be selected.
● Altering the design of the wax pattern. A special wax
pattern witha plastic mesh on the tissue surface and a
polished external surface is fabricated and cast.
73
73. ● The cast retainer will have a meshwork on the tissue
surface, which aids in mechanical interlocking of the
resin.
● Dentures fabricated using this technique are called cast
mesh fixed partial dentures
74
74. ● Incorporating water soluble salt crystals "Lost salt
technique
● Here water-soluble salt crystals are sprinkled onto the
die before fabricating the retainer pattern. Hence, the
crystals line the tissue surface of the wax pattern. The
retainer patterns are first fabricated using resin.
● The resin is polymerized and the salt crystals are
dissolved by washing and ultrasonic cleansing
75
75. ● The dissolved salts form voids on the tissue surface of
the resin pattern.
● The resin patterns with the voids are invested, burned
out and cast.
● The cast metal retainers will have the same voids, which
act as centers for mechanical retention.
● This technique is followed in Virginia bridges
76
76. ● Chemical bonding of resin
● Chemical bonding between the resin and the metal
retainer can be produced by chemical etching or tin-
plating or using
● chemical adhesives.
● Chemical etching
77
77. ● A gel consisting of Nitric and Hydrochloric acids applied
to the internal surface of the metal framework for
approxmately 25 minutes.
● As electrolytic etching s extremely technique sensitive,
chemical etching may be mnore relable as it is a single
procedure
78
78. ● Tin-plating
● Tin has the ability to form organic complexes with
several specific adhesive resins resulting in significantly
greater bond strengths.
● Precious alloys can be plated with tin and used as
frameworks for resin retained fixed partial denture.
79
79. ● Bonding Agents (Cements)
● Composite resins play an important role in the bonding
of the metal framework to etched enamel.
● Other resin adhesives that are commonly used include, 4
META (4 methacryloxy ethyl trimellitic anhydride),MDP (O-
methacryloylo-xyde cyl dihydrogen phosphate).
80
80. ● These resins do not require acid etching as they bond
chemically with the retainer.
● An opaque composite resin can be incorporated into the
resin cement to minimize graying effect.
81