This study evaluated enamel surface roughness after removing orthodontic bracket adhesives using different methods. Forty teeth were divided into four groups and treated with either a low-speed tungsten carbide bur, high-speed tungsten carbide bur, ultrafine diamond bur, or Er:YAG laser. Enamel roughness was measured before and after adhesive removal and polishing. Removal with low-speed bur caused no significant roughness change, while diamond bur and laser caused irreversible roughness increase. Laser removal resulted in the highest post-removal roughness values. Proper technique selection can minimize enamel damage from adhesive removal.
Comparative evaluation of the etching patter of er.cr and acid etching on ext...Mireya Ramírez
This study compared the etching patterns of enamel and dentin surfaces produced by Er,Cr:YSGG laser etching and conventional acid etching using 37% phosphoric acid. 40 extracted human teeth were sectioned to produce enamel and dentin specimens, which were divided into control, acid-etched, and laser-etched groups. The specimens were analyzed using environmental scanning electron microscopy. For enamel, both methods largely removed the smear layer without significant difference. Acid etching produced predominantly Type I etching patterns while laser etching resulted in Type III patterns. For dentin, both methods mostly removed the smear layer without difference. However, laser etching opened dentinal tubules to a significantly smaller diameter than acid etching. This study thus evaluated the micro
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
This document discusses air abrasion technology for dental applications. It begins by introducing the concept of minimally invasive dentistry and how air abrasion aids in removing carious hard tissue with little damage to sound structures. While air abrasion was introduced in the 1940s, it did not gain popularity initially due to limitations in materials, cavity preparation techniques, and suction capabilities. The document describes how air abrasion works using compressed gas to direct aluminum oxide particles to remove tooth structure. It outlines the parameters that control tooth removal and discusses improved bonding agents and restorative materials that have allowed air abrasion to become more widely used for applications like removing caries, preparing teeth for restorations, and removing old restorations. Access
1) The study compared the effects of gingival displacement cords and cordless systems on gingival crevice closure, displacement, and inflammation.
2) It found that while cords provided better gingival displacement than cordless systems, cordless systems like Expasyl caused less inflammation of the gingiva.
3) All materials tested maintained an adequate sulcal width for up to 60 seconds after removal, but the cordless material Expasyl achieved the narrowest sulcal width, risking defects in the dental impression.
Synopsis presentation Evaluation of tubular penetration depth of a sealer aft...pratiklovehoney
Evaluation of tubular penetration depth of a sealer after irrigation with four root canal irrigants of different origin- 6% Morinda Citrifolia juice, 0.2% Chitosan, 17% EDTA, 3% NaOCl-an in vitro study
The bond strength of endodontic sealers to root /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.
Comparative evaluation of the etching patter of er.cr and acid etching on ext...Mireya Ramírez
This study compared the etching patterns of enamel and dentin surfaces produced by Er,Cr:YSGG laser etching and conventional acid etching using 37% phosphoric acid. 40 extracted human teeth were sectioned to produce enamel and dentin specimens, which were divided into control, acid-etched, and laser-etched groups. The specimens were analyzed using environmental scanning electron microscopy. For enamel, both methods largely removed the smear layer without significant difference. Acid etching produced predominantly Type I etching patterns while laser etching resulted in Type III patterns. For dentin, both methods mostly removed the smear layer without difference. However, laser etching opened dentinal tubules to a significantly smaller diameter than acid etching. This study thus evaluated the micro
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
This document discusses air abrasion technology for dental applications. It begins by introducing the concept of minimally invasive dentistry and how air abrasion aids in removing carious hard tissue with little damage to sound structures. While air abrasion was introduced in the 1940s, it did not gain popularity initially due to limitations in materials, cavity preparation techniques, and suction capabilities. The document describes how air abrasion works using compressed gas to direct aluminum oxide particles to remove tooth structure. It outlines the parameters that control tooth removal and discusses improved bonding agents and restorative materials that have allowed air abrasion to become more widely used for applications like removing caries, preparing teeth for restorations, and removing old restorations. Access
1) The study compared the effects of gingival displacement cords and cordless systems on gingival crevice closure, displacement, and inflammation.
2) It found that while cords provided better gingival displacement than cordless systems, cordless systems like Expasyl caused less inflammation of the gingiva.
3) All materials tested maintained an adequate sulcal width for up to 60 seconds after removal, but the cordless material Expasyl achieved the narrowest sulcal width, risking defects in the dental impression.
Synopsis presentation Evaluation of tubular penetration depth of a sealer aft...pratiklovehoney
Evaluation of tubular penetration depth of a sealer after irrigation with four root canal irrigants of different origin- 6% Morinda Citrifolia juice, 0.2% Chitosan, 17% EDTA, 3% NaOCl-an in vitro study
The bond strength of endodontic sealers to root /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.
New development in careis removal and restorationNUHA ELKADIKI
This document discusses new developments in caries removal and restoration techniques. It describes several laser, air abrasion, polymer bur, micropreparation bur, and chemo-mechanical methods that have been introduced to remove only infected dentin and preserve healthy tooth structure. These include lasers, air abrasion, polymer burs, photoactivated disinfection using dye and lasers, and Carisolv gel. The document also discusses caries detector dyes that help distinguish between infected and healthy dentin to guide conservative caries removal. Overall, the goal of new methods is to remove infected material while minimizing removal of healthy tooth structure.
The double cord technique involves placing a small diameter cord in the gingival sulcus first, leaving it in place, and then packing a larger diameter cord over the first cord to provide additional retraction and hemostasis for making impressions of multiple prepared teeth or when the gingival tissues are compromised. The small inner cord provides retraction while the outer cord provides additional hemostasis and tissue displacement needed for accurate impressions.
Track 6. Technological innovations in biomedical training and practice
Authors: Alessandro Ruggiero, Roberto D'Amato, Ludovico Sbordone, Fernando Blaya and Antonio Lanza
1) Accurate impressions require an exact duplicate of the prepared tooth and surrounding structures to produce a precise cast.
2) Choice of impression material depends on factors like personal preference, ease of use, strength, accuracy, and cost.
3) Popular materials for final impressions include polysulfides, hydrocolloids, condensation silicones, polyvinyl siloxanes, and polyethers.
This document discusses various techniques for gingival displacement during dental impressions. It describes mechanical methods like copper bands and matrices, as well as chemomechanical methods using retraction cords impregnated with chemicals like aluminum chloride. Newer injection techniques using materials like Expa-Syl that displace tissue mechanically while controlling bleeding are also covered. The benefits and drawbacks of each technique are assessed in terms of effectiveness, risk of trauma or tissue damage, and other factors. A variety of retraction cord designs, sizes and application methods are also outlined. The document emphasizes that proper gingival displacement is important for accurately recording finish lines and preparing high quality dental impressions.
Moisture control & soft tissue manipulation / fixed orthodontics coursesIndian dental academy
This document discusses moisture control and soft tissue management in fixed prosthodontics. It begins with an introduction stating that complete control of the operative site is essential during restorative procedures and that gingival tissues must be displaced to access subgingingival margins. It then reviews literature on various retraction techniques and agents. This includes studies on the effects of retraction materials on gingival tissues, techniques to eliminate cords, and comparisons of different retraction methods. The document also covers fluid control measures, chemical agents to reduce moisture, and gingival retraction methods both mechanical and chemical.
1. Gingival tissue management techniques are used to displace gingival tissues from the operating site for various dental procedures like cavity preparation and crown placement.
2. Common techniques include use of retraction cords, chemicals, lasers and surgical excision to provide a dry field and control bleeding from the gingival tissues.
3. Retraction cords soaked in chemical agents like adrenaline are placed into the gingival sulcus to retract tissues, while techniques like electrocautery and lasers provide precise cutting with less bleeding.
Digital technology in maxillofacial rehabiltationDr.Rohit Mistry
This document discusses the application of digital technologies like rapid prototyping and 3D printing in maxillofacial prosthetics. It outlines the history and types of rapid prototyping processes. Clinical applications discussed include surgical planning, fabrication of cranial implants and dental models, and construction of prosthetics to rehabilitate defects. Limitations and essential factors for successful adoption are also reviewed. Virtual reality and its potential for surgical simulation is presented. The document concludes that while promising, widespread application requires continued research and development of appropriate materials, as well as training and collaboration between clinicians and technology developers.
Bond strength of orthodontic brackets /certified fixed orthodontic courses b...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 provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
Description :
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
This document provides an overview of pit and fissure sealants. It discusses the history, definition, morphology, materials used, application process, advantages, and recent advances. Key points include:
- Pit and fissure sealants were developed in the 1950s to isolate deep pits and fissures from the oral cavity and prevent dental caries.
- The application process involves cleaning, isolating, and etching the tooth surface, followed by placement of the sealant material into the pits and fissures.
- Common materials used are resin-based sealants and glass ionomer cement. Recent advances include self-etching and fluoride-releasing sealants.
- Proper application
This document discusses different methods for soft tissue management and gingival retraction during dental procedures. It covers the use of retraction cords made of 100% cotton to retract gingiva and achieve hemostasis when soaked in a solution. Various sizes of retraction cords are recommended for different areas of the mouth. Hemostatic agents like aluminum chloride, aluminum sulfate, and ferric sulfate can be used with the cords. Newer retraction cords are designed to eliminate issues like time consumption, patient discomfort, and epithelial attachment damage by maintaining rigidity in the sulcus without needing pressure for application.
This document discusses cosmetic polishing and debridement of dental implants. It describes coronal polishing as a procedure to remove extrinsic stains from tooth enamel for aesthetic reasons, with no therapeutic benefit. Two common methods of polishing are discussed: the rubber cup method using a polishing agent and slow rotating cup, and the air-powder method using a mixture of warm water and polishing powder delivered by air. The document outlines indications, contraindications, techniques, and safety precautions for both methods.
structure and components of the smear layer/ rotary endodontic courses by ind...Indian dental academy
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.
This document discusses various methods for fluid control and soft tissue management during dental procedures. It describes the objectives of fluid control as removing fluids, isolating tissues, enhancing visibility and patient comfort. Methods discussed include rubber dams, absorbents, high vacuum suction, saliva ejectors, anti-sialogogues and local anesthetic. Gingival retraction techniques aim to displace gingiva and expose margins, including mechanical methods like rubber dams and cords, and mechanochemical methods using hemostatic and astringent chemicals impregnated in cords. Popular chemicals discussed are epinephrine, alum, aluminum chloride and ferric sulfate.
Air abrasion is a new dental technology that can replace traditional drills in some situations like early tooth decay. It works by using compressed air to propel aluminum oxide particles that spray away decayed parts of the tooth without heat, sound, pressure or vibration. Some advantages over drills include reduced need for anesthesia, preserving more healthy tooth tissue, keeping the work area dry, and lower risk of cracking or chipping teeth.
Este documento describe la energía nuclear de fisión. Explica que la fisión nuclear es la división del núcleo de un átomo en fragmentos más pequeños, liberando energía debido a la diferencia de masa. También describe que las reacciones en cadena ocurren cuando los neutrones liberados por una fisión causan más fisiones en otros núcleos, liberando más neutrones y continuando la reacción en cadena.
New development in careis removal and restorationNUHA ELKADIKI
This document discusses new developments in caries removal and restoration techniques. It describes several laser, air abrasion, polymer bur, micropreparation bur, and chemo-mechanical methods that have been introduced to remove only infected dentin and preserve healthy tooth structure. These include lasers, air abrasion, polymer burs, photoactivated disinfection using dye and lasers, and Carisolv gel. The document also discusses caries detector dyes that help distinguish between infected and healthy dentin to guide conservative caries removal. Overall, the goal of new methods is to remove infected material while minimizing removal of healthy tooth structure.
The double cord technique involves placing a small diameter cord in the gingival sulcus first, leaving it in place, and then packing a larger diameter cord over the first cord to provide additional retraction and hemostasis for making impressions of multiple prepared teeth or when the gingival tissues are compromised. The small inner cord provides retraction while the outer cord provides additional hemostasis and tissue displacement needed for accurate impressions.
Track 6. Technological innovations in biomedical training and practice
Authors: Alessandro Ruggiero, Roberto D'Amato, Ludovico Sbordone, Fernando Blaya and Antonio Lanza
1) Accurate impressions require an exact duplicate of the prepared tooth and surrounding structures to produce a precise cast.
2) Choice of impression material depends on factors like personal preference, ease of use, strength, accuracy, and cost.
3) Popular materials for final impressions include polysulfides, hydrocolloids, condensation silicones, polyvinyl siloxanes, and polyethers.
This document discusses various techniques for gingival displacement during dental impressions. It describes mechanical methods like copper bands and matrices, as well as chemomechanical methods using retraction cords impregnated with chemicals like aluminum chloride. Newer injection techniques using materials like Expa-Syl that displace tissue mechanically while controlling bleeding are also covered. The benefits and drawbacks of each technique are assessed in terms of effectiveness, risk of trauma or tissue damage, and other factors. A variety of retraction cord designs, sizes and application methods are also outlined. The document emphasizes that proper gingival displacement is important for accurately recording finish lines and preparing high quality dental impressions.
Moisture control & soft tissue manipulation / fixed orthodontics coursesIndian dental academy
This document discusses moisture control and soft tissue management in fixed prosthodontics. It begins with an introduction stating that complete control of the operative site is essential during restorative procedures and that gingival tissues must be displaced to access subgingingival margins. It then reviews literature on various retraction techniques and agents. This includes studies on the effects of retraction materials on gingival tissues, techniques to eliminate cords, and comparisons of different retraction methods. The document also covers fluid control measures, chemical agents to reduce moisture, and gingival retraction methods both mechanical and chemical.
1. Gingival tissue management techniques are used to displace gingival tissues from the operating site for various dental procedures like cavity preparation and crown placement.
2. Common techniques include use of retraction cords, chemicals, lasers and surgical excision to provide a dry field and control bleeding from the gingival tissues.
3. Retraction cords soaked in chemical agents like adrenaline are placed into the gingival sulcus to retract tissues, while techniques like electrocautery and lasers provide precise cutting with less bleeding.
Digital technology in maxillofacial rehabiltationDr.Rohit Mistry
This document discusses the application of digital technologies like rapid prototyping and 3D printing in maxillofacial prosthetics. It outlines the history and types of rapid prototyping processes. Clinical applications discussed include surgical planning, fabrication of cranial implants and dental models, and construction of prosthetics to rehabilitate defects. Limitations and essential factors for successful adoption are also reviewed. Virtual reality and its potential for surgical simulation is presented. The document concludes that while promising, widespread application requires continued research and development of appropriate materials, as well as training and collaboration between clinicians and technology developers.
Bond strength of orthodontic brackets /certified fixed orthodontic courses b...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 provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
Description :
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
This document provides an overview of pit and fissure sealants. It discusses the history, definition, morphology, materials used, application process, advantages, and recent advances. Key points include:
- Pit and fissure sealants were developed in the 1950s to isolate deep pits and fissures from the oral cavity and prevent dental caries.
- The application process involves cleaning, isolating, and etching the tooth surface, followed by placement of the sealant material into the pits and fissures.
- Common materials used are resin-based sealants and glass ionomer cement. Recent advances include self-etching and fluoride-releasing sealants.
- Proper application
This document discusses different methods for soft tissue management and gingival retraction during dental procedures. It covers the use of retraction cords made of 100% cotton to retract gingiva and achieve hemostasis when soaked in a solution. Various sizes of retraction cords are recommended for different areas of the mouth. Hemostatic agents like aluminum chloride, aluminum sulfate, and ferric sulfate can be used with the cords. Newer retraction cords are designed to eliminate issues like time consumption, patient discomfort, and epithelial attachment damage by maintaining rigidity in the sulcus without needing pressure for application.
This document discusses cosmetic polishing and debridement of dental implants. It describes coronal polishing as a procedure to remove extrinsic stains from tooth enamel for aesthetic reasons, with no therapeutic benefit. Two common methods of polishing are discussed: the rubber cup method using a polishing agent and slow rotating cup, and the air-powder method using a mixture of warm water and polishing powder delivered by air. The document outlines indications, contraindications, techniques, and safety precautions for both methods.
structure and components of the smear layer/ rotary endodontic courses by ind...Indian dental academy
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.
This document discusses various methods for fluid control and soft tissue management during dental procedures. It describes the objectives of fluid control as removing fluids, isolating tissues, enhancing visibility and patient comfort. Methods discussed include rubber dams, absorbents, high vacuum suction, saliva ejectors, anti-sialogogues and local anesthetic. Gingival retraction techniques aim to displace gingiva and expose margins, including mechanical methods like rubber dams and cords, and mechanochemical methods using hemostatic and astringent chemicals impregnated in cords. Popular chemicals discussed are epinephrine, alum, aluminum chloride and ferric sulfate.
Air abrasion is a new dental technology that can replace traditional drills in some situations like early tooth decay. It works by using compressed air to propel aluminum oxide particles that spray away decayed parts of the tooth without heat, sound, pressure or vibration. Some advantages over drills include reduced need for anesthesia, preserving more healthy tooth tissue, keeping the work area dry, and lower risk of cracking or chipping teeth.
Este documento describe la energía nuclear de fisión. Explica que la fisión nuclear es la división del núcleo de un átomo en fragmentos más pequeños, liberando energía debido a la diferencia de masa. También describe que las reacciones en cadena ocurren cuando los neutrones liberados por una fisión causan más fisiones en otros núcleos, liberando más neutrones y continuando la reacción en cadena.
A saga Rocky conta a história de Rocky Balboa, um boxeador de baixa categoria de Filadélfia que recebe a chance de lutar pelo título mundial contra o campeão Apollo Creed. Ao longo de seis filmes, Rocky supera adversidades e desafios dentro e fora do ringue, encontrando o amor e a redenção através do boxe.
Textura Corporation reported strong revenue growth of 33% year-over-year for the quarter ended December 31, 2015. Revenues were $23.7 million with billings of $26.5 million, representing 34% growth. The company provided 2016 guidance of 23-29% revenue growth to $23.7-$24.7 million for Q1 2016 and 22-28% growth to $106-$111 million for the full year. Textura expects to continue executing its growth strategy through increased functionality, market penetration, and international expansion.
El documento presenta el memorando de planeamiento para realizar un examen especial al área de abastecimientos del Gobierno Regional de Junín para el periodo 2010. El examen evaluará los estados financieros, el cumplimiento normativo, los objetivos y metas presupuestarias, y el control interno. El periodo a examinar es de enero a diciembre de 2010.
The document discusses Jolt, a customizable employee management tool used by over 250 brands. It allows managers to [1] automate routine tasks like checklists, audits, and forms; [2] improve communication through a digital logbook and notifications; [3] provide training materials, documents and media; [4] access centralized reporting and analytics; and [5] manage employee scheduling, time, and attendance. The goal is to increase productivity, save labor, and ensure consistency through updated mobile-accessible processes and content.
This document discusses underwater construction techniques. It describes caissons and cofferdams which are used to create dry work environments for underwater foundations. Caissons are watertight retaining structures that can be pumped out to stay dry, while cofferdams are temporary structures built to block water flow. The document also discusses underwater concreting methods like the tremie method and pump method. Finally, it provides examples of structures built using these techniques like bridges, dams, offshore oil platforms, and proposes some future underwater structures like hotels and tunnels.
PMC-S waterproofing system is a 8 years innovative R&D effort by Jiazhou New Waterproofing Co., Ltd. and Southwest Jiaotong University.This system is a specialized waterproofing solution for tunnels and underground projects.(If applied to exposed sites like roof,etc,2cm thickness protective layer is required).
This system won China's highest honor National Science and Technology Progress Award in 2011 and also won 6 Invention Patents and 8 Utility-Model Patents.
PMC-S is successfully applied in Munigou Highway Tunnels(over 3000 meters altitude,extreme conditions),Shenzhen LNG Terminal(China's first LNG Terminal),Najing Youth Olympic Axis Underground Project(the biggest underground project),Langzhong Railway Station Underpass,Pengzhou Petrochemical Tanks Bottom Waterproofing projects,etc.
The main Benefits of PMC-S:
1.Fast curing:the membrane forms within 3 to 8 seconds after spraying on by instant oxidantion and deoxidantion chemical change in the spray gun.
2.30% Self-recovering:the membrane absorb the moisture to self-recover from the wound by construction operation
3.Long existing with the building:Unlike other waterproofing work,there will be a reparing after 3-5 years.With PMC-S applied projects,the endless and huge amount of budget for repairing is no longer a problem.
4.Fully bonded system provides excellent watertightness, preventing development of
water migration in both concrete membrane interfaces
5.Eco-friendly,non toxic component
6.Efficient Operation,fast installation,shorten the construction period time
7.Fireproof: A1 Grade
The document discusses the anatomy and physiology of teeth. It begins by explaining how proper tooth form and alignment promotes efficiency during chewing. It then describes various protective and functional aspects of tooth form, including proximal contact areas, interproximal areas, embrasures, heights of contour, and curvature of the cementoenamel junction. For each structure, it provides details on their importance, location on different teeth, and comparisons between maxillary and mandibular teeth. It also discusses axial alignment of teeth and compares the anatomical features of maxillary central and lateral incisors. In summary, the document provides an in-depth overview of tooth morphology and its relationship to function.
Impact of formulation and process variables on solid-state stability of theop...Dhaval shah
This study investigated the impact of formulation and processing variables on the solid-state stability of theophylline in controlled-release formulations over 3 months of storage. Twelve formulations were prepared using a full factorial design to examine the effects of polymer type, diluent, granulation method (wet vs. dry), and granulation fluid (water vs. isopropanol) on the transition of anhydrous theophylline to the monohydrate form. Physicochemical analysis revealed a decrease in tablet hardness and increase in moisture content for all wet-granulated formulations, which underwent a solid-state transition to the monohydrate, compared to no transition in dry-compressed or isopropanol granulated formulations. The transition decreased
This document summarizes a study that compares the bond strength of orthodontic brackets bonded to enamel surfaces prepared by different methods: phosphoric acid etching, Er:YAG laser etching, a combination of acid etching and laser etching, and laser etching followed by acid etching. Sixty human premolars were divided into four groups based on the enamel preparation method used. Brackets were bonded to the prepared enamel surfaces using a standard protocol. The bond strength of each sample was then tested using a universal testing machine. The study aims to investigate methods that provide maximum bond strength and analyze the fracture mode for each preparation method.
This document summarizes a study that evaluated the wear resistance of nine different dental cements when tested against human enamel. The cements included self-adhesive resins, self-etch resins, total-etch resins, resin modified glass ionomers, and zinc-phosphate. Specimens of each cement were prepared and cured via light or chemical modes. The specimens and enamel cusps were then used in a wear test to compare the wear resistance of the different cements and curing methods. Statistical analysis was conducted on the results to determine any significant differences in wear between the cement types and curing methods.
smear layer in endodontics/ rotary endodontic courses by indian dental academyIndian dental academy
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.
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
This study evaluated and compared the shear bond strength of orthodontic brackets that were rebonded using three different techniques: sandblasting, direct flaming, and grinding with a green stone bur. Sixty extracted premolars were bonded with brackets and divided into groups for each rebonding technique. A universal testing machine measured the shear bond strength of the rebonded brackets. Scanning electron microscopy examined the surface characteristics of new and rebonded bracket bases. Sandblasting yielded the highest bond strength and well-defined retentive areas, while flaming and grinding filled retentive areas and reduced bond strength. Sandblasting is the best technique for rebonding brackets to achieve high bond strength.
This document provides an overview of debonding procedures in orthodontics. It discusses the objective of restoring the tooth surface after removing attachments and adhesive resin. It describes different procedures for removing steel and ceramic brackets, as well as residual adhesive, using mechanical methods, electrothermal debonding, lasers, or ultrasonic tools. It compares the advantages and disadvantages of these debonding methods and discusses indices for evaluating the amount of remaining adhesive and surface changes to the enamel.
This document discusses the use of ultrasound in endodontics. It describes two main methods of ultrasound production: magnetostriction and piezoelectric. Piezoelectric units are preferred as they produce linear motion without heat. Applications of ultrasound include access preparation, removing obstructions, activating irrigants, condensing gutta-percha, placing MTA, and surgical procedures like root-end cavity preparation and placement of root-end filling material. Ultrasound offers benefits like cleaner canals, less invasive surgery, and better filling of materials. A variety of tips are available for different procedures.
This document discusses and compares several nickel titanium rotary root canal instrumentation systems, including Lightspeed, ProFile, EndoSequence, and K3. It provides details on their designs and evaluations of their efficacy, such as cleaning ability, preparation time, risk of ledging or instrument separation. Studies found that while rotary systems reduced preparation time compared to manual instrumentation, there were few differences in cleaning efficacy or healing of periapical lesions between methods. Later generation systems like EndoSequence and ProFile were found to have improved shaping ability and reduced risk of canal transportation.
SEALING ABILITY OF MTA FOR REPAIR OF LATERAL ROOT PERFORATIONJAMES RAJAN
This study compared the sealing ability of mineral trioxide aggregate (MTA), amalgam, and IRM for repairing lateral root perforations using methylene blue dye. MTA showed significantly less dye penetration at an average of 0.28mm compared to amalgam at 1.52mm and IRM at 1.30mm. While amalgam and IRM showed considerable dye leakage, MTA provided the best seal of the perforations. The results suggest that MTA is superior to amalgam and IRM for repairing lateral root perforations due to its ability to better seal the perforation site.
Investigation of the Remineralization Effect Tnrough Scanning Electron Micros...IJERA Editor
Background: Local fluoride varnishes have been widely used as a method of non-operative treatment and for
caries preventive interventions for more than three decades.
Purpose: Evaluation of the remineralization effect by means of electron microscopy of mineralization varnish -
Clinpro ™ White Varnish with TCP (Tri-Calcium phosphate) (3M).
Materials and Methods: The material used is from 20 temporary intact teeth, extracted due to physiological
change with permanent teeth, with a completely preserved structure and anatomy of crowns and fully
physiologically resorbed roots. For the purposes of the study a scanning electron microscope JEOL JSM 6390 is
used with an attachment for element analysis (EDS INCA of Oxford). Prepared samples are pre-coated with
gold (cathode sputtering with apparatus JEOL JFC – 1200) to obtain a better contrast of the SEM image of early
carious lesions on the smooth surfaces of the temporary teeth, with predilection for development of caries with a
d1 threshold. For this purpose the two processes were monitored occurring continuously on the enamel surfacede-
and remineralization. Performed was computer processing of the digital images.
Results: There is presence of certain minerals deposited in the embossed enamel prisms after of
remineralization. The chemical analysis established the presence of calcium (Ca2 +
), around the organic matrix.
Demineralised surface has pores present of around 1%, which is visible through the enamel on the surface of the
deciduous teeth looking like filled and pores looking like partially covered, filled with newly formed and
growing crystals. The crystals, which are hydroxylapatite, fluorapatite or fluorhydroxiapatite gradually connect,
growing and forming mineral structure filling the microscopi defects and the pores from the demineralisation in
the surface enamel prismless layer.
Ultrasonic inserts can be used for various applications in endodontics including surgical endodontics and non-surgical endodontics. Piezoelectric ultrasonic inserts vibrate linearly and are preferred over magnetostrictive inserts. They are classified based on design and use. Applications include root-end cavity preparation for surgery, removing obstructions like posts or separated instruments, and improving irrigant flow and effectiveness. Different tip designs are suited to specific tasks. Proper power settings and technique are important for safe and effective use.
Applications of ultrasonics in endodonticsMettinaAngela
This document discusses various applications of ultrasonics in endodontics. It covers topics like ultrasonic retreatment to remove gutta percha fillings, using ultrasonics for access refinement and to manage calcifications, removing separated instruments from the root canal, and retrieving old posts. Ultrasonics provides benefits for these procedures like more efficient removal of materials, enhanced safety and control, and minimal damage to tooth structure compared to other techniques. Specific tips, techniques and case reports are presented for different clinical applications of ultrasonics in endodontic retreatment and procedures.
This document discusses the use of an Er:YAG laser to treat periapical lesions by removing microbial contamination from the root apex. The study evaluated the efficacy of an Er:YAG laser on removing microbiological apical biofilm (MAB) and infected cementum from extracted human teeth with periapical lesions. Scanning electron microscopy showed that laser irradiation vaporized part of the infected cementum and MAB from irradiated areas without exposing the underlying dentin. The findings suggest the Er:YAG laser may be effective for removing MAB. However, further research is needed to evaluate its clinical use.
1. The study evaluated the effect of different surface treatments of fiber posts on the bond strength between the post and root dentin when using a resin luting agent.
2. Sixty teeth were treated with five different post surface conditions before cementation with resin luting agent. The surface treatments included no treatment, chloroform, chloroform with silane, sandblasting, and sandblasting with silane.
3. Micro push-out testing found that sandblasting followed by silane produced the highest bond strength between the post and dentin. There was no significant difference between using chloroform alone or with silane.
Soft And Hard Tissue Management Using LasersAndres Cardona
This document discusses the use of lasers in soft and hard tissue management for esthetic dental procedures. It provides background on the history and mechanisms of dental lasers. The erbium laser wavelength is highlighted as it allows conservative, less invasive treatment of both hard tissues like enamel and bone as well as soft tissues. Specific techniques described include laser-assisted cavity preparation and restoration, as well as cosmetic procedures like gingival contouring and osseous crown lengthening to enhance the smile. Case studies demonstrate how these laser techniques can be used to adjust gingival levels and proportions for esthetic outcomes.
The document discusses the role and importance of adhesive dentistry. It describes the different generations of dentine bonding agents from the early phosphoric acid-based systems to newer self-etch adhesives. Key challenges in dentine adhesion are the structural differences between enamel and dentine such as dentine's high water content and presence of a smear layer. Conditioning with acid or chelators is needed to remove the smear layer and expose collagen fibers for bonding to occur. Current adhesive systems are classified as etch-and-rinse or self-etch and involve either two or three step application processes.
The document discusses the role and development of dentine bonding agents. It describes the challenges of bonding to dentine due to its structure and composition compared to enamel. Various generations of bonding agents are classified, from early phosphoric acid-based systems to modern multi-step etch-and-rinse and self-etch adhesives. Conditioning of the dentine surface and the role of priming agents are explained. Factors affecting the bonding process such as smear layer removal and acid etching duration are also covered.
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Journal club presentaion on zirconia fixed partial dentured on endodonticaloy...NAMITHA ANAND
The study investigated the effects of different post and core material combinations on surface strain of zirconia fixed partial denture (FPD) margins. Artificial abutment teeth were restored with either resin composite cores with glass fiber posts or cast metal alloy posts and cores. Strain gauges measured surface strain on the zirconia frameworks and abutment roots under static loading. The results showed that restoring the premolar with a cast post and core and the molar with a resin composite core reduced stress concentration in both the frameworks and abutment teeth compared to the other combination. The study suggests considering post and core material properties and differences in abutment tooth morphology when selecting materials for zirconia FPD
This document analyzes the polishability of six types of Jordanian limestone by measuring surface roughness and gloss values after subjecting stone samples to different polishing stages. Crystalline limestones produced the lowest roughness and highest gloss, while chalk had the worst results. Low porosity stones gave better polishability. Equations were developed using regression analysis to predict roughness and gloss based on stone properties like porosity, strength, and mineral composition. The final polishing stage produced the smoothest and most reflective surfaces.
Similar to Enamel surface roughness after debonding of orthodontic brackets and various clean up techniques (20)
2. 10/30/2014 Enamel Surface Roughness after Debonding of Orthodontic Brackets and Various Clean-Up Techniques
enamel damage on tooth surface, and thus these methods could not be recommended for removing adhesive
remnants after debonding of orthodontic brackets.
Keywords: Laser, Solid-state; Dental Debonding; Enamel; Orthodontics
INTRODUCTION
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Debonding aims to remove orthodontic attachments and all remaining adhesives from the tooth and to restore the
surface to its pretreatment state as much as possible [1]. Mechanical removal of remaining composite after
debonding has been shown to be detrimental for enamel surface, causing a significant amount of enamel loss [2–5]
and irreversible enamel damage [6–9]. The presence of prominent areas or grooves on the tooth surface can
contribute to enamel staining and plaque accumulation which in turn may cause esthetic concerns and enamel
demineralization. Although the occurrence of scarring on the enamel surface after adhesive removal appears to be
inevitable, the damage can be reduced to a negligible level if selecting a proper technique.
So far, different modalities have been used to remove adhesive remnants after debonding including hand
instruments (pliers and scalers), various burs, Soflex discs, ultrasonic devices and air abrasion units. Tungsten
carbide burs used in low [8, 10] or high [11] speed handpieces have been frequently shown to produce the most
satisfactory results, but some studies found that they are more damaging than a green rubber wheel [6], an
innovative a finishing carbide bur [12] or a fiber-reinforced composite bur [13] for tooth enamel. The use of
diamond finishing burs for composite removal is also popular among some dentists because of their relatively weak
abrasive potential. However, these burs can cause irreversible enamel damage [6, 8, 14], which may be due to the
shape of the bur or its sharpness [15]. Another technology that can be used for composite removal is laser. In
orthodontics, lasers have been investigated for their efficacy in enamel etching [16, 17], increasing enamel
resistance to caries [18, 19], reconditioning of metallic or ceramic brackets [20, 21], enhancing tooth movement
[22, 23] and pain relief [24, 25]. A Great attempt has also been made to use this technology for selectively
removing restorative materials without damaging the tooth structure. Although different laser wavelengths have
been used experimentally for enamel clean-up [26–28], it is well clear that erbium family lasers are more suited for
this purpose. The application of Er:YAG (erbium: yttrium-aluminum-garnet) laser in removing restorative materials
from cavity walls has been investigated in previous studies [29–31]. However, the data are limited regarding the
use of erbium lasers in cleaning the enamel surface after bracket removal. Using SEM images, Almedia et al. [32]
found that the Er:YAG laser performed significantly better than the conventional technique in removing composite
remnants after debonding of orthodontic brackets, although it produced a significantly higher amount of enamel
loss compared to that observed in the tungsten-carbide bur group. Evaluating the effects of different instruments on
enamel surface have been commonly performed qualitatively using scanning electron microscope (SEM) or
stereomicroscope images to describe the surface topography. However, employing quantitative scales for this
purpose allows for better comparison of the damage caused by different instruments, thus enhancing selection of a
more efficient, but less hazardous one for enamel clean-up. The aim of this study was to evaluate the efficacy of an
Er:YAG laser compared to different rotary burs in removing adhesive remnants after debonding of orthodontic
brackets.
MATERIALS AND METHODS
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The sample consisted of 40 maxillary first or second premolars removed because of orthodontic purposes. The
selected teeth were intact and without any caries, cracks or hypoplasia on the enamel surface. The teeth were
cleaned from soft tissue remnants and the roots were cut off approximately 2 mm below the cemento-enamel
junction. The crowns were embedded in self-curing acrylic resin using moulds of 25 mm in diameter and 20 mm in
height, in such a way that the buccal surface of the tooth would be oriented horizontally and about 1–2 mm above
the rim of the mould. The mounted teeth were randomly divided into four experimental groups of 10 and a number
was assigned to each specimen. The blocks were kept in distilled water at room temperature during the time of the
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experiment in order to prevent dehydration. The buccal surface of each tooth was covered by two layers of nail
varnish, keeping a circular area of 3 mm in diameter on the middle part exposed to provide the same area of
measurement in different treatment stages. Before bonding, the surface profile was analyzed at the center of the
exposed area using a contact prophylometer (Talysurf 120 L; Rank Taylor Hobson, Leicester, England) with a
stylus tip oriented perpendicular to the enamel surface during scanning (initial stage).
The analysis was performed with a cut off of 0.25 mm and a maximum length of 1.2 mm, recording four roughness
parameters as follows:
1-Ra (arithmetic mean value of surface roughness): Ra indicates the average roughness and is defined as
the arithmetic mean deviation of the surface valleys and peaks from the center line in the measuring length.
2-Rq (root mean square roughness): Rq is the root mean square deviation of the assessed profile. The Rq
of a surface is approximately 10% greater than the Ra value.
3-Rt (maximum roughness height): Rt is the maximum peak-to-valley height over the sampling length.
6-Rz (mean roughness depth): Rz is the mean vertical distance between the highest peak and the deepest
valley of five adjacent measuring sections.
The measurements were made twice for each specimen and the mean value was recorded.
After the first surface roughness measurement, the buccal surfaces were etched with 37% orthophosphoric acid gel
for 30 seconds, rinsed thoroughly with water and dried with compressed air.
Transbond XT primer (Monrovia, CA, USA, 3M Unite) was coated on the enamel surface. Then, a layer of
vaseline was applied on the bonding pad of a stainless steel standard edgewise second premolar bracket
(Dentaurum, Ispringen, Germany) to prevent composite adhesion to the bracket base; consequently, leaving the
complete adhesive on the enamel surface.
A sufficient amount of adhesive was later placed on the base and the bracket was pressed in the middle of the
exposed area. The excess adhesive was removed with a dental explorer and each tooth was cured for a total of 40
seconds from occlusal, gingival, mesial and distal directions (10 seconds each). Curing was performed with
Bluephase C8 (Ivoclar Vivadent, Schaan, Liechtenstein) light emitting diode (LED) using a power density of 650
mW/cm2.
Then, the bracket was removed easily using a pair of tweezers, leaving all the adhesive remained on the enamel
surface. This procedure was repeated for all the specimens.
The adhesive remained after debonding was removed by using different instruments. In the first group, the adhesive
was removed with a 12-fluted tungsten carbide bur (Dentaurum no. 123–604, Ispringen, Germany) operated at low
speed by air cooling. A tungsten carbide bur in group 2 (SS White Burs, Inc. no. 15664-5, Lakewood, NJ, USA)
and an ultrafine diamond finishing bur (SS White Burs, Inc. no. 859-016, Lakewood, NJ, USA) in group 3 were
used for cleaning adhesive remnants, both connected to a high speed handpiece with water cooling. In the fourth
group, the composite was removed with an Er:YAG laser device (Fidelis Plus II, Fotona, Slovenia) irradiating a
wavelength of 2940 nm. The laser operated with a pulse energy of 250 mJ, pulse duration of 350 μs (long pulse)
and a pulse repetition rate of 4 Hz under air and water cooling.
The laser beam was directed in a focused, non-contact mode and perpendicular to the enamel surface using RO7
handpiece.
The clean up procedures in all groups were performed by the principal investigator and great care was undertaken
not to damage the surrounding enamel. The process of adhesive removal was continued until no adhesive remained
on visual inspection and the enamel surface felt smooth without any projection during tactile examination with a
dental explorer. After adhesive removal, the surface was subjected for the second time to contact profilometry
analysis and the roughness values were recorded (adhesive removal stage).
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Finally, all the specimens received polishing with rubber prophy cups (Product Code: ORRA3360, Astek
Innovations Ltd, Altrincham, United Kingdom)and water slurry of fine pumice (Patterson Dental Co., Sacramento,
CA, USA) for 10 seconds, after which the third profilometry measurement was taken (finishing stage).
Statistical analysis
The normality of the data was confirmed by the Kolmogorov-Smirnov test and the homogeneity of variances by the
Levene’s test. The data were analyzed by a repeated measure analysis of variance through the SPSS software
(Version 11.5, Chicago, Illinois, USA). The level of significance was determined at p<0.05.
RESULT
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The repeated measure analysis of variance showed a significant interaction between the method of adhesive
removal and the treatment stage (p<0.001).
Therefore, one way analysis of variance was performed to delineate statistical differences in surface roughness
parameters between the study groups in each treatment interval.
Pairwise comparisons between groups were made by Duncan test. Significant differences in surface roughness
parameters of each group between different treatment stages were assessed by repeated measure analysis of
variance and LSD test.
Comparison between different treatment intervals
Figures 1 to 4 present the surface roughness parameters of the four experimental groups at different stages (initial,
adhesive removal and finishing). There was no significant difference in surface irregularity between the treatment
intervals when a 12-fluted TC bur was used for adhesive removal (p>0.05) (Fig 1). For the high speed TC bur (
Fig 2), no significant difference was found for Ra and Rq parameters between treatment stages (p>0.05), but
statistical differences were observed for Rt and Rz measurements (p<0.05). The repeated measure ANOVA
revealed that Rt and Rz parameters were significantly lower in the initial stage compared to both the adhesive
removal and finishing stages, which were not statistically different from each other. In both ultrafine diamond bur (
Fig 3) and Er:YAG laser (Fig 4) groups, there were significant differences in all surface roughness measurements
between the different treatment stages (p<0.01), so that the highest roughness values were found after adhesive
removal and the lowest values were observed in the initial stage. The overall findings of this study implied that
application of a TC bur at low-speed is the safest method regarding the damage caused to the enamel surface. The
degree of irreversible enamel damage is minimal when using a TC bur at high-speed, while adhesive removal with
an ultrafine diamond bur and especially by an Er:YAG laser can cause a significant and irreversible increase in the
enamel surface irregularity.
Fig 1
Surface roughness parameters of the low speed TC bur group at different
treatment stages.
Fig 2
Surface roughness parameters of the high speed TC bur group at different
treatment stages
Fig 3
Surface roughness parameters of the ultrafine diamond bur group at different
treatment stages.
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Fig 4
Surface roughness parameters of the Er:YAG laser group at different treatment stages.
Comparison between different methods of adhesive removal
The results of ANOVA demonstrated no significant difference in surface irregularity between the study groups at
the initial stage (p>0.05), but significant differences were noted in the adhesive removal and finishing intervals
(p<0.001). Subsequent analysis with Duncan test revealed that in both the adhesive removal (Table 1) and finishing
(Table 2) stages, TC bur operated in low speed handpiece produced significantly lower surface roughness values
than the diamond bur and Er:YAG laser, while ultrafine diamond bur produced a significantly less roughened
surface than the Er:YAG laser (p<0.05).
Table 1
Comparison of Surface Roughness Parameters Among Study Groups in the
Adhesive Removal Stage
Table 2
Comparison of Surface Roughness Parameters Among Study Groups in the
Finishing Stage
The surface irregularity of teeth cleaned with the high speed TC bur was between those acheived with the low
speed TC and diamond burs, showing comparable irregularity with both of these groups (Tables 1 and 2). The only
exception was found in the finishing stage (Table 2), where Rt value of the diamond bur group was comparable to
those of both TC bur groups. The present study investigated the efficacy of different rotary instruments and
Er:YAG laser in removing adhesive residues after debonding of orthodontic brackets using contact profilometry to
measure surface irregularity. Instead of evaluating experimental surfaces with a control group without intervention,
surface roughness of the same teeth was measured in different treatment stages.
This method is more precise because when the comparison is made between different specimens, one could not be
ensured whether surface damage has been created by the removal technique or has been present before the bonding
procedure [33]. The end of the cleaning process was determined by visual examination and checking of the tooth
surface with a dental explorer in order to more closely simulate clinical conditions. In agreement with most of the
previous studies [11, 15, 34–36], water cooling was preferred to air cooling during the use of high speed handpiece
to prevent excessive increase in intra pulpal temperature. Ra, the mathematical average of profile deviation from the
mean line in a sampling depth, is usually considered as representative for enamel surface texture, but it suffers some
faults, as it cannot differentiate between heights or valleys or between grooves with shallow or deep length [7]. To
have a better view of surface irregularity, other roughness parameters were also measured in this in vitro
experiment.
When different treatment intervals were compared in each group, it was found that the application of tungsten
carbide bur at low speed was the least hazardous method for enamel, because the surface irregularity was not
significantly different in teeth cleaned with this bur in the three treatment intervals. After enamel clean-up with the
high-speed TC bur, small increases were observed in surface roughness parameters, which were significant for Rt
and Rz parameters, but not for Ra and Rq. This indicates that enamel clean up by a high-speed TC bur produces
some degree of enamel damage as represented by the increased surface irregularity. Hannah and Smith [37] also
emphasized that the TC bur should be used at low speed because adhesive removal at high speed would be
hazardous to the adjacent enamel. The enamel surfaces cleaned by the ultra fine diamond bur and the Er:YAG laser
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showed severe and irreversible enamel damage which was not reversed to the pretreatment level after final
pumicing. Comparison between various clean-up methods demonstrated that in general, application of tungsten
carbide burs in low or high speed handpieces produced the least amount of surface irregularity. However, the
surface roughness values of specimens cleaned with the high speed TC bur were also comparable to those of the
diamond bur group. Actually, the numeric values of surface roughness parameters were greater in the high-speed
TC bur group than the low-speed TC bur group in both the adhesive removal and finishing stages, but the
differences between the two groups were not statistically significant.
These findings are in agreement with those of Zachrisson and Artun [8] who found that the most adequate results
were obtained after resin removal with TC burs operated in low speed handpiece. Campbell [11] reported that the
use of no. 30 fluted TC bur in high speed handpiece was the most efficient modality for removing resin remnants
after debonding and produced the least amount of scarring clinically. In contrast, Gwinnett and Gorelick [6] found
that the use of high speed TC bur after debonding was damaging for the enamel surface due to the creation of large
pits and facets and causing significant enamel loss.
The surfaces cleaned with an ultrafine diamond bur, although acceptable compared to those cleaned with the
Er:YAG laser, showed significantly greater surface irregularity than the low-speed TC bur group in both the
adhesive removal and finishing stages, indicating that the use of diamond bur should not be considered acceptable
for resin removal after debonding.
This finding is in agreement with those of previous studies [8, 10, 11, 14, 34]. Retief and Denys [14] reported that
diamond finishing burs created grooves with superimposed abrasion marks on the resin-enamel surfaces. Campbell
[11] reported that the use of diamond bur to remove adhesive remnants after debonding caused severe scarring on
the enamel surface that was visible both clinically and in SEM photomicrographs. Using scanning electron
micrographs, Zachrisson and Arthun [8] concluded that the use of diamond burs for finishing was unacceptable,
due to the creation of devastating roughness and enamel loss. In both the adhesive removal and finishing stages, the
roughest surface was obtained after enamel cleaning with the Er:YAG laser. Furthermore, it was difficult to remove
the entire adhesive with the Er:YAG laser without damaging the surrounding enamel. These findings corroborate
the study of Correa-Afonso et al. [29], who reported surface irregularities, a great amount of remaining restorative
material and minimal inadvertent removal of healthy tooth tissue after using Er:YAG laser for removing composite
restoration. Almedia et al. [32] found that the Er:YAG laser performed significantly better than the conventional
technique for removing adhesive after bracket removal, but the amount of enamel ablation was considerably greater
in the laser group. In the present study, Er:YAG laser was used with a pulse repetition rate of 4 Hz, pulse energy of
250 mJ and pulse duration of 350 μs (long pulse).
Pulse repetition rate has been considered as the most important parameter in determining heat accumulation in the
tissue during the ablation procedure [38], encouraging the use of low pulse repetition rates to have a safe
preparation [38]. Furthermore, selecting a high repetition rate necessitates the use of high water stream and this can
make observation of the operating field difficult [29]. Correa-Afonso et al. [29] found that increasing the pulse
repetition rate provided faster and more effective ablation of composite resin, but it caused greater removal of the
healthy surrounding tissues and produced more irregularities in cavities prepared by the Er:YAG laser. In the
present study, a pulse repetition rate of 4 Hz was used in order to prevent iatrogenic damage to the tooth tissue. The
pulse energy of 250 mJ provided the minimum energy required for composite resin removal while minimizing the
possibility of healthy tissue ablation. Hibst and Keller [31] found that the ablation rate of restorative materials
depended on the pulse energy chosen and suggested energies between 250 mJ and 350 mJ necessary to achieve
successful results.
Correa-Afonso et al. [29] considered a pulse energy of 250 mJ as the safest energy to prevent inadvertent removal
of healthy tissues when removing composite fillings with the Er:YAG laser.
The excessive roughness observed in the laser group may be related to the ablation mechanism of Er:YAG laser
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which causes melted areas in the material and explodes it, subsequently pulling out the adhesive from the enamel
surface. In contrast, adhesive removal with a dental handpiece occurs by wearing out the material, providing a
better control of the procedure because of the more suitable tactile feedback for the clinician [29].
In the present study, final polishing with pumice failed to restore the enamel surface to the pretreatment level.
In the diamond bur and Er:YAG laser groups, pumicing caused a significant decrease in surface roughness
parameters between the adhesive removal and finishing stages, but the surfaces still demonstrated statistically more
irregularity compared to the initial measurement.
This finding is in agreement with those of the previous authors [8, 35] who found that final pumicing slightly
smoothened the rough surfaces obtained after adhesive removal, but it could not entirely remove the deeper
scratches or gouges left by different instruments. The findings of this study; however, are in contrast with those of
Burapavong et al. [39], who reported that final polishing with pumice left most surfaces free of remaining adhesive
and restored smoothness to the treated enamel surface. Although findings of this study advocate the use of low-speed
demonstrated faint scratching and scarring after its use for enamel clean-up, suggesting that the use of this bur
should also be done carefully and followed by polishing techniques in order to obtain the finest surface topography
as possible.
Further development in technology is needed in the field of laser to achieve the characteristics and type of laser that
can ablate the composite differentially from the tooth structure without causing tissue damage.
DISCUSSION
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On the basis of the results achieved inside the limitations of this study:
1. Application of a TC bur at low speed proved to be the safest method of removing adhesive remnants after
debonding of orthodontic brackets.
2. A small increase was observed in surface roughness parameters after adhesive removal by a TC bur at
high speed which was significant for Rt and Rz parameters, but not for Ra and Rq measurements.
Although the damage appeared to be clinically negligible, adhesive removal by a TC bur at high speed
should be performed carefully.
3. Use of a very fine diamond bur or an Er:YAG laser for enamel clean up caused a significant increase in
surface irregularity. Therefore, these methods cannot be advocated for adhesive removal after debonding
of orthodontic brackets.
4. In comparison between groups, the application of TC burs at low- or high- speed handpieces produced the
least amount of enamel roughness, while enamel clean-up by the Er:YAG laser caused the highest
roughness measurements.
5. The increased roughness observed after the use of high-speed TC and diamond burs or the Er:YAG laser
did not return to the pretreatment level after final pumicing, indicating an irreversible enamel damage.
Acknowledgments
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The authors would like to thank the research chancellor of Mashhad University of Medical Sciences for the
financial support of this research [grant number 88236]. The results presented in this work have been taken from a
student’s thesis (No # 2450).
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