This document discusses the history, mechanisms, and effects of dental bleaching. It begins with a brief history of bleaching, noting the introduction of chloride lime in 1848 and hydrogen peroxide in 1910. The most common bleaching agents are hydrogen peroxide, sodium perborate, and carbamide peroxide. Bleaching works via an oxidation reaction where reactive oxygen radicals interact with colored molecules in enamel and dentin. The document then discusses various bleaching techniques and their effects on tooth structure and restorations. Specifically, bleaching can cause decreased microhardness and changes to the bonding interface that impact restoration durability.
JOURNAL CLUB: Terminology of Dental Caries and Dental Caries Management: Cons...Urvashi Sodvadiya
Vita Machiulskienea, Guglielmo Campusb, c Joana Christina, Carvalhod Irene, Digee Kim, Rud Ekstrandf, Anahita Jablonski-Momenig, Marisa Maltzh, David J. ,Mantoni Stefania, Martignonj, k E. Angeles, Martinez-Mierl, Nigel B., Pittsj Andreas G., Schultem Christian, H. Spliethn, Livia Maria, Andaló Tenutao, Andrea Ferreira Zandonap, Bente Nyvade
CARIES RESEARCH; OCT 2019
JOURNAL CLUB: Terminology of Dental Caries and Dental Caries Management: Cons...Urvashi Sodvadiya
Vita Machiulskienea, Guglielmo Campusb, c Joana Christina, Carvalhod Irene, Digee Kim, Rud Ekstrandf, Anahita Jablonski-Momenig, Marisa Maltzh, David J. ,Mantoni Stefania, Martignonj, k E. Angeles, Martinez-Mierl, Nigel B., Pittsj Andreas G., Schultem Christian, H. Spliethn, Livia Maria, Andaló Tenutao, Andrea Ferreira Zandonap, Bente Nyvade
CARIES RESEARCH; OCT 2019
Evaluation of Marginal integrity and Depth of Cure for three ‘bulk fill’ comp...pratiklovehoney
Evaluation of Marginal integrity and Depth of Cure for three ‘bulk fill’ composites : SDR, Tetric Evoceram Bulk Fill Composite and EverX Posterior Bulk Fill Composite - An In Vitro study
Comparison of Different Dentin Pretreatment Protocols on the Bond Strength of...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.
Comparative evaluation of treatment of noncarious cervical hypersensitivity b...DR.AJAY BABU GUTTI M.D.S
Comparative evaluation of treatment of noncarious
cervical hypersensitivity by a fluoride varnish, a
dentin bonding agent, and Er, Cr:YSGG laser: An
in vivo study JCD 2020
Minimally invasive dentistry (MID) is an evidence based intervention approach supported internationally that aims to do the least harm to effected and surrounding tissues
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.
The permanent teeth with open apex and large periapical lesion are diffcult to treat as a traditional root canal procedure, therefore calcium hydroxide place an important role in reducing the periapical infl ammation. Management of open apex can be done using mineral trioxide aggregate (MTA) which can be placed in apical 3-4 mm. The aim of this This case report describes the use of mineral trioxide aggregate (MTA) for management of a periapically compromised immature tooth.
Intentional replantation of maxillary second molar; case report and 15-year f...Abu-Hussein Muhamad
Abstract: Intentional reimplantation is a procedure in which tooth extraction is performed followed by reinsertion of the extracted tooth into its own socket after performing the desired procedure. In this article, intentional reimplantation is described and discussed as a treatment approach for aperiapical lesion that is in maxillary second molar. After 15 years, the patient was asymptomatic, the tooth was still functional and a recall intraoral periapical radiograph showed an intact periodontal ligament space and lamina dura with no evidence of gross root resorption or ankylosis.
Keywords: Intentional replantation, calcified canals, mineral trioxide aggregate
DENTAL AVULSION- IMMEDIATE REPLANTATION: 8- YEAR FOLLOW UP CASEAbu-Hussein Muhamad
Avulsion of permanent front teeth is a rare accident , mostly affecting children between seven and nine year s of age.
Replanted and splinted, these teeth often develop inflammat ion, severe resorption or ankylosis affect ing alveolar bone
development and have to be extracted sooner or later . This repor t proposes a discussion on the var ious pecul iar ities of a
tooth avulsion case with immediate replantation, such as a long retent ion per iod, root canal fil ling with MTA, or thodontic
treatment.
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.
The black box of orthodontic research is now in its second edition. This book is considered as a reference for orthodontic professionals who look for validation
and optimization of their basic knowledge, experience and updated research concerning
the orthodontic field.
The continuing development in orthodontic materials and mechanics led researchers
from different countries to employ their efforts and capabilities to investigate any relation
between these and their use in orthodontic treatment. Running multiple studies scenarios
for different populations, needs to be organized and ranked according to article type and
methodology incorporated to simplify the process of referencing and validating each
orthodontic procedure used.
For this, it was my honorable opportunity to give a hand in this issue. For most orthodontic
subjects encountered daily in practice, the most leading results, statements and conclusions
of concern mentioned in literature will be documented in order of publishing time.
Considering theses, beside focusing on the mentioned reference, will give orthodontists
the whole picture of the stroy.
It should be stated here that more focus on the leading orthodontic journals will be
noticed. Any valuable notes for the purpose of improving the way the book is presented
for audience will be of our great appreciation.
Raed H. Alrbata
Evaluation of Marginal integrity and Depth of Cure for three ‘bulk fill’ comp...pratiklovehoney
Evaluation of Marginal integrity and Depth of Cure for three ‘bulk fill’ composites : SDR, Tetric Evoceram Bulk Fill Composite and EverX Posterior Bulk Fill Composite - An In Vitro study
Comparison of Different Dentin Pretreatment Protocols on the Bond Strength of...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.
Comparative evaluation of treatment of noncarious cervical hypersensitivity b...DR.AJAY BABU GUTTI M.D.S
Comparative evaluation of treatment of noncarious
cervical hypersensitivity by a fluoride varnish, a
dentin bonding agent, and Er, Cr:YSGG laser: An
in vivo study JCD 2020
Minimally invasive dentistry (MID) is an evidence based intervention approach supported internationally that aims to do the least harm to effected and surrounding tissues
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.
The permanent teeth with open apex and large periapical lesion are diffcult to treat as a traditional root canal procedure, therefore calcium hydroxide place an important role in reducing the periapical infl ammation. Management of open apex can be done using mineral trioxide aggregate (MTA) which can be placed in apical 3-4 mm. The aim of this This case report describes the use of mineral trioxide aggregate (MTA) for management of a periapically compromised immature tooth.
Intentional replantation of maxillary second molar; case report and 15-year f...Abu-Hussein Muhamad
Abstract: Intentional reimplantation is a procedure in which tooth extraction is performed followed by reinsertion of the extracted tooth into its own socket after performing the desired procedure. In this article, intentional reimplantation is described and discussed as a treatment approach for aperiapical lesion that is in maxillary second molar. After 15 years, the patient was asymptomatic, the tooth was still functional and a recall intraoral periapical radiograph showed an intact periodontal ligament space and lamina dura with no evidence of gross root resorption or ankylosis.
Keywords: Intentional replantation, calcified canals, mineral trioxide aggregate
DENTAL AVULSION- IMMEDIATE REPLANTATION: 8- YEAR FOLLOW UP CASEAbu-Hussein Muhamad
Avulsion of permanent front teeth is a rare accident , mostly affecting children between seven and nine year s of age.
Replanted and splinted, these teeth often develop inflammat ion, severe resorption or ankylosis affect ing alveolar bone
development and have to be extracted sooner or later . This repor t proposes a discussion on the var ious pecul iar ities of a
tooth avulsion case with immediate replantation, such as a long retent ion per iod, root canal fil ling with MTA, or thodontic
treatment.
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.
The black box of orthodontic research is now in its second edition. This book is considered as a reference for orthodontic professionals who look for validation
and optimization of their basic knowledge, experience and updated research concerning
the orthodontic field.
The continuing development in orthodontic materials and mechanics led researchers
from different countries to employ their efforts and capabilities to investigate any relation
between these and their use in orthodontic treatment. Running multiple studies scenarios
for different populations, needs to be organized and ranked according to article type and
methodology incorporated to simplify the process of referencing and validating each
orthodontic procedure used.
For this, it was my honorable opportunity to give a hand in this issue. For most orthodontic
subjects encountered daily in practice, the most leading results, statements and conclusions
of concern mentioned in literature will be documented in order of publishing time.
Considering theses, beside focusing on the mentioned reference, will give orthodontists
the whole picture of the stroy.
It should be stated here that more focus on the leading orthodontic journals will be
noticed. Any valuable notes for the purpose of improving the way the book is presented
for audience will be of our great appreciation.
Raed H. Alrbata
Recent advances in orthodontic materials 8th ios-pgsc /certified fixed orth...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
Recent advances in orthodontic materials /certified fixed orthodontic cours...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
Introduction
History
Mechanism of action
Antimicrobial effect
Tissue dissolving efficacy
NaOCl and bioflim
Factors affecting Antimicrobial and tissu
e dissolving efficacy
Haemostatic property
Buffered NaOCl
Effect of increasing temperature on NaOCl
NaOCl and dentin
Effect of NaOCl on resin-dentin interface
Effect of NaOCl on endodontic instruments
Combination of NaOCl with different irrigants
Commercially available NaOCl based irrigants
Sodium Hypochlorite accidents
Hulsman’s criteria
Clinical manifestation
Management
Prevention
Conclusion
References
As an intracanal medicament
Definition
Clinical application
Mechanism of action
Vehicles
Placement of Calcium hydroxide paste
Dentin and Calcium hydroxide
Effect of Calcium hydroxide on clinical outcome
Calcium hydroxide and Chlorhexidine
Calcium hydroxide and Sodium Hypochlorite
Removal of Calcium hydroxide from the canal
When to replace Calcium hydroxide dressing?
Calcium hydroxide and CO2
Toxicity
As a Root canal Sealer
Clinical significance
Classification
Composition
Properties
Leakage
Solubility
- In tissue fluids
- In chemical solvent
Biocompatibility
Antimicrobial
Toxicity
Conclusion
References
Introduction
Basic chemistry
Properties
Manufacture
In dentistry…
History
Calcium hydroxide as a liner
Traditional versus current concept in
Mechanism of action
Antimicrobial
Biological
Bridge formation
Choices of materials as liner
Classification
Conventional Calcium Hydroxide liners
Light cured Calcium Hydroxide liners
Calcium hydroxide as a base
Comparative evaluation of properties
Calcium release
Alkalizing activity
Porosity, Water sorption and solubility
Antibacterial property
Cytotoxicity
Bridge formation
Effects of acid etching on properties of CH
Pulpal inflammation
Drawbacks of Calcium Hydroxide
Calcium hydroxide versus MTA
Conclusion
References
Introduction
Principles of tooth preparation
Preservation of tooth structure
Retention form
taper
Surface area
Freedom of movement
Length
Resistance form
Height/width ratio
path of insertion
Structural durability
Occlusal reduction
Functional cusp bevel
Axial reduction
Preservation of periodontium
Types of margin
Biological consideration
Conclusion
References
Introduction
Prevention of caries
Brief introduction about types of Immunity
Causative factors of dental caries
Virulance of S mutans
Natural immune barriers
Salivary secretion and its composition
Natural barriers
Innate immune responses of dental pulp to caries
Acquisition of oral microbes
Factors affecting oral microbial colonization
Innate salivary factors found in oral cavity
Adaptive immunity
Secretary IgA
Types of Immunization
Routes of Immunization
Conclusion
Introduction
Classification of endodontic emergency
According to P Carrotte
According to Walton and Torabinejad
According to Weine
Importance of diagnosis in endodontic emergency
Types of diagnostic Aids needed
Emergency treatment of pulp and periapical related diseases
Acute pulpitis
Acute pulpitis with apical periodontitis
Pulp necrosis
Acute periapical abscess
Emergency treatment of traumatic injuries
Crown fracture
Root fracture
Avulsion
Andreasen’s criteria
Summer’s criteria
Emergency therapy for intratreatment pain
Endodontic emergency after treatment
Medication in endodontic emergency
Conclusion
References
Introduction
Portals of entry to the pulp
Concepts of infection
Focus of infection
Zones of Fish
Kronfeld’s mountain pass theory
Older v/s Newer Concepts in endodontics
Endodontics: When to do and When not to do?
Vital pulp therapy
Rationale of Pulpotomy
Vital pulp therapy over root canal therapy
Root canal therapy over vital pulp therapy
Rationale of Apexification
Conclusion
References
Introduction
Clinical application of images
+ Case documentation
+ Laboratory communication
+ Patient education
+ Dental education
Dental photography
Preoperative photography
+ Extraoral photography
# Full face- front and profile
# Dentofacial smile
# Close-up lip photographs
Intraoral photography
# Occlusal photographs
# Full dentition retracted view (Front & Lateral)
- Teeth slightly open & in occlusion
# Maxillary Anterior teeth
Postoperative photography
Features of camera
+ Lenses
# Close-Up photography lenses (Macro lenses)
# Alternatives to Macro lenses
+ Focal length
+ Working distance
+ Magnification ratio
Principle-based photography concepts
+ Exposure control
# Factors affecting exposure control
# Exposure modes
+ White balance
+ Depth of field
Camera system equipment
+ Classification of camera based on a recording of the image
+ Most common types of camera currently available
# Digital Single-lens reflex camera (DSLR)
# Pocket-sized cameras
# Portable electronic devices
How to select a camera
Important features in choosing an SLR camera
+ Lenses
+ Number of pixels
+ Functions
+ Available cameras for dental photography
Understanding lighting
+ Flashes
# Ring flash versus Point source flash
+ Accessories for Smartphone
+ How to modify the light system?
+ F-Stop and Flash setting
Accessories for Intraoral photography
+ Retractors
+ Photographic mirror
+ Contrasters
Basic general photographic technique
Technical problems area
+ Camera
+ Film
+ Developing
Image management
+ File format and compression
Summery
Conclusion
References
- Introduction
- Development
- Epithelial enamel organ
- Amelogenesis
The life cycle of ameloblast
Morphogenic stage
Organizing stage
Formative/ secretary stage
Development of Tome’s processes
Maturation stage
Stages of maturation
- Difference between hypoplastic and hypo mineralized enamel
-Molar-incisor hypomineralization (MIH)
-Amelogenesis imperfecta
-Dental fluorosis
-Protective stage
-Importance of reduced enamel epithelium
-Desmolytic stage
-Chemical properties
Inorganic part
Structure of hydroxyapatite
Clinical significance
Organic part
Types of protein
Water
-Basic Structural elements of enamel
Rods
Direction of rods
Interrod enamel
Rod sheath
Enamel crystals arrangement and its importance
Rodless enamel
-Physical characteristics
Density
Thickness
Hardness & Strength
Compressive and tensile strength of enamel
Brittleness
Factors associated with attrition
Enamel and ceramic restoration
Solubility
-Acid etching of enamel
-Factors affecting the acid etching
-Contamination of surface
-Concentration and time of acid etching
-Type of enamel
-Effect of bleaching and bleaching agents on Physical properties of enamel
-Comparison between physical properties of tooth structure and restorative material
-Translucency
-Specific gravity
-Permeability
-Permeability and structure of enamel
-Factors affecting permeability
-Colour
-Factors affecting color
-White spot lesion
-Deep dentinal caries
-Histology
-Hunter- Schreger bands
Types and its clinical significance
Incremental lines of Retzius
-Enamel lamellae
-Enamel spindles
-Enamel tufts
-Neonatal line
-Gnarled enamel
-Dentinoenamel junction
-Cementoenamel junction
-Difference between Deciduous and Permanent enamel
-Repair of Enamel
-Surface structure
-Prismless enamel
-Perikymata
-Rod ends
-Pits Surface elevation
-Enamel caps
-Enamel brochs
Enamel cuticle
Primary enamel cuticle/ Nasmyth’s membrane
Secondary enamel cuticle
Pellicle
Age changes
Conclusion
Previously asked questions
References
- Introduction
- Normal anatomy of kidney
- Nephron
- Juxtaglomerular apparatus
- Clearance
- tubular function
- Regulation of water and ion reabsorption
- Types of water reabsorption
- Mechanism of urine concentration and dilution
- Countercurrent mechanism
- Definition
- Uses of culture media
- Basic composition of culture media
- Types of culture media
--Based on physical state
----solid medium
----semi solid medium
----liquid medium
--Based on ingredients
----Simple or basal medium.
----Complex medium.
----Synthetic or defined medium.
----Semisynthetic medium.
--Special medium
----Enriched media
----Enrichment media
----Selective media
----Differential media
----Indicator media
----Transport media
----Anaerobic media
-Media preparation
-Culture method
--Streak culture
--Lawn culture
-references
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
JOURNAL CLUB: Stability of Bonded Resin Composite Restorations toEnamel after Bleaching with 20% Carbamide Peroxide
1.
2. BLEACHING
History
1848 Evidence of chloride lime used as nonvital tooth bleaching
1864 Truman introduced a technique for non-vital bleaching, Which
used chlorine from a solution of calcium hydrochlorite along
with acetic acid.
late 1800s Other bleaching agents mentioned in the literature
1910 30% hydrogen peroxide
1960 10% carbamide peroxide
Haywood VB. History, safety, and effectiveness of current bleaching techniques and applications of the nightguard vital bleaching technique. Quintessence International
(Berlin, Germany: 1985). 1992;23(7):471-488.
3. BLEACHING AGENTS
Most commonly used agents for dental bleaching:
• Hydrogen peroxide HP (H2O2) (1930s)
• Sodium perborate
• Carbamide peroxide CP (CH6N4O3) (1989: haywood and heymann)
10% of CP
3.35% HP (H2O2) & 6.65% urea (CH4N2O)
Effect of HP = 2.76 times faster than CP
Li Y. Biological properties of peroxide-containing tooth whiteners. Food Chem Toxicol. Sep 1996;34(9):887-904.
Albers HF. Lightening natural teeth. ADEPT Report. 1991;2(1):1-24.
4. MECHANISM OF ACTION
“Oxidation Reaction”
water molecule (H2O), hydrogen ion (H), highly reactive free
oxygen (O) radicals
H2O2
Highly reactive radicals
organic matrix of enamel and dentin
React with organic colored molecules
convert the carbon-ring molecules into
chains
Kwon S-R, Ko S-H, Greenwall L. Tooth whitening in esthetic dentistry: Principles and techniques. Vol 1. London, UK: Quintessence Publishing Co, Ltd; 2009
6. EFFECT OF BLEACHING AGENTS ON TOOTH STRUCTURE
Ruse et al(1990), studied bovine enamel after exposure to 35-37% HP and
found a significant increase in the nitrogen level. In addition, a thick organic
rich layer was found, that was resistant to acid etching.
Shannon et al (1993), studied enamel microhardness after the application of
10% CP bleaching agents. A significant decrease in microhardness was found
after 2 weeks of exposure.
Sulieman and his colleagues (2004) conducted a study investigating the safety
of 35% HP on enamel and dentin structure. The researchers observed no
evidence of damaging effects of 35% HP on enamel or dentin.
Ruse ND, Smith DC, Torneck CD, Titley KC. Preliminary surface analysis of etched, bleached, and normal bovine enamel. J Dent Res. Sep 1990;69(9):1610- 1613.
Shannon H, Spencer P, Gross K, Tira D. Characterization of enamel exposed to 10% carbamide peroxide bleaching agents. Quintessence Int. Jan 1993;24(1):39-44.
Sulieman M, Addy M, Macdonald E, Rees JS. A safety study in vitro for the effects of an in-office bleaching system on the integrity of enamel and dentine. J Dent. Sep
2004;32(7):581-590.
7. Bleaching material: undesirable effects on the natural tooth structure
• Bonding interface
• Restorative materials, such as softening and degradation of the teeth
and restorative materials
How bleaching agents react with preexisting or subsequent dental restorations
is essential.
8. AIM
To evaluate the effect of postoperative home bleaching
procedures using 20% carbamide peroxide on the shear bond
strengths of different adhesive systems to enamel and to verify
the failure mode for each test specimen
9. METHODOLOGY
A total of 100 sound human molars were cleaned and kept in distilled water
The roots were cut from the teeth 2 mm below the cementoenamel junction with a
slow-speed diamond disk
The teeth were embedded in a self-cure acrylic resin that was filled in polyvinyl
chloride cylindrical molds in a manner that permitted the buccal surfaces to be
exposed.
10. MATERIALS USED:
Filtek Z350 XT Universal nanocomposite resin
Opalescence PF 20%
Ultra-etch acid etchant
OptiBond Solo Plus Used as Total-etch (etch-andrinse technique)
Single Bond Universal Used as Total-etch (etch-andrinse) and self-etch techniques
Tetric N-Bond Universal Used as Total-etch (etch-andrinse) and self-etch techniques
n = 100
n = 50 n = 50
OptiBond (OB)
Solo: as total-
etch
Single Bond
Universal
adhesive : as
total-etch
Single Bond
Universal
adhesive : as
self-etch Tetric N-Bond
Universal
adhesive: as
total-etch
Tetric N-Bond
Universal
adhesive: as
self-etch
11. After dental adhesive application, resin composite posts (Filtek Z350 XT; 3M ESPE
Dental Products, St. Paul, MN, USA) were fabricated in each specimen, using
custom-made silicone molds (3 mm in diameter, 2 mm high)
After resin
composite post
fabrication
Afterward, all specimens were kept in distilled water at 37°C for 24 hours
and thermo-cycled for 5000 cycles in a thermocycling apparatus
(Thermocycler 1100/1200; SD Mechatronik, Germany).
Storage: in artificial saliva at 37°C for 1 week
Control group: shear bond test
Postoperative bleaching group: Carbamide peroxide
bleaching material (Opalescence PF 20%; Ultradent®
Products, Inc., South Jordan, UT, USA) for 14 consecutive
days to simulate the home bleaching technique
After bleaching
gel application
12. The shear bond testing procedures were accomplished using a universal
testing machine (Instron 5965; Instron, Norwood, MA, USA) and a load cell of 10 kN at a
crosshead speed of 0.5 mm/min.
The failure modes of the debonded specimens were analyzed using a digital
microscope (KH-7700; Hirox, Hackensack, NJ, USA) at 50× magnification
Scanning electron microscope (SEM) (JSM-6360LV; JEOL, Tokyo, Japan) was used to
observe the bonding interfaces of the resin composite posts
17. o Multi-mode or multi-purpose adhesives
o Can be applied using the TE or SE approach
o Performance of these universal adhesives is material dependent
o Stable resin composite bonding to enamel: etch-and-rinse adhesives
o Less stable resin composite bonding to enamel: self etch adhesives
Perdigao J, Gomes G, Gondo R, Fundingsland JW. In vitro bonding performance of all-in-one adhesives. Part I–microtensile bond strengths. J Adhes Dent.
2006;8(6):367-373.
Carvalho RM, Manso AP, Geraldeli S, Tay FR, Pashley DH. Durability of bonds and clinical success of adhesive restorations. Dent Mater. 2012;28(1):72-86.
Tay FR, Pashley DH, King NM, Carvalho RM, Tsai J, Lai SC, Marquezini L., Jr Aggressiveness of self-etch adhesives on unground enamel. Oper Dent. 2004;29(3):309-
316.
Perdigao J, Lopes MM, Lambrechts P, Leitao J, Van Meerbeek B, Vanharle G. Effects of a self-etching primer on enamel shear bond strengths and SEM morphology. Am
J Dent. 1997;10(3):141-146.
However, in contrast to present study, other studies did not identify a
difference in the bond strength to enamel between TE and SE adhesives.
18. SINGLE BOND
Universal Adhesive
o Chemical bonding: between the
acidic methacryloxydecyl
dihydrogen phosphate (MDP) and
enamel
o Stable and durable interfaces, good
mechanical properties, and an
improved rate of conversion of its
hydrophobic resin
TETRIC N-BOND
Universal Adhesive
o Hydrophilic hydroxyethyl methacrylate
(HEMA),
o Hydrophobic decanediol
dimethacrylate (D3MA),
o Intermediate bisphenol A glycidyl
methacrylate (bisgma)monomers,
o MDP,
o Methacrylated carboxylic acid polymer
(MCAP)
de Lima E, Santos R, Durao M, Nascimento A, Braz R. Universal cements: dual activated and chemically activated. Acta BiomaterOdontol Scand. 2016;2(1):125-129.
Jayasheel A, Niranjan N, Pamidi H, Suryakanth MB. Comparative evaluation of shear bond strength of universal dental adhesives -an in vitro study. J Clin Exp Dent.
2017;9(7):e892-e896
19. o The bond strength relies mainly on the adhesive’s capability to
demineralize the smear layer and the underlying tooth structure.
o TNB-TE and SB-TE adhesives: high bond strength values to unbleached
and bleached enamel, likely owing to properly etched enamel surfaces
o OB adhesive VS SB-SE adhesive: NOT significantly different; control (non-
bleach) and postoperative bleaching groups
Gandhi G, Kalra JPS, Goyal A, Sharma A. Microphotographic assessment of enamel surface using self-etching primer and conventional phosphoric acid: an in vitro study.
Contemp Clin Dent. 2018;9(1):15-19.
Elmourad A, Alqahtani M. Effects of pre- and post-simulated home bleaching with 10% carbamide peroxide on the shear bond strengths of different adhesives to enamel.
The Saudi Journal for Dental Research. 2014;5(2):81-92.
20. Peroxide radicals
Bonded interface margins
Deterioration of bond strength to
enamel
This detrimental effect of peroxide radicals on adhesive bonds is reported to
increase with higher concentrations of carbamide peroxide
21. Effect of Carbamide
Peroxide Bleaching Gel
Concentration on the
Bond Strength of Dental
Substrates and Resin
Composite
Barcellos DC, Benetti P, Fernandes VV, Valera MC. Effect of carbamide peroxide bleaching gel concentration on the bond strength of dental substrates and resin
composite. Operative dentistry. 2010 Jul;35(4):463-9.
22. Control non-bleach group Postoperative bleaching group
OptiBond Solo Plus
Single Bond Universal adhesive
(total-etch technique)
Single Bond Universal adhesive
(Self-etch technique)
Tetric N-Bond Universal adhesive
(Total-etch technique)
Tetric N-Bond Universal adhesive
(Self-etch technique)
Scanning Electron Microscope Testing
24. CONCLUSION
o Higher concentration of bleaching agents may significantly deteriorate
the bond strength of resin composite restorations; therefore, using a
lower concentration of these agents might guarantee less detrimental
effects on the adhesive joints.
o It is advisable to pre-treat the enamel with phosphoric acid etching
when using SE adhesives to ensure better bond strength values.
25. CLINICAL SIGNIFICANCE
Replacement of bonded resin composite restorations might be
considered after bleaching procedures, especially if these
restorations were previously bonded with SE adhesives.
26. REFERENCES
1. Calderini A, Sciara S, Semeria C, Pantaleo G, Polizzi E. Comparative clinical and psychosocial benefits of tooth
bleaching: different light activation of a 38% peroxide gel in a preliminary case-control study. Clin Case Rep.
2016;4(8):728-735.
2. Haywood VB, Heymann HO. Nightguard vital bleaching. Quintessence Int. 1989;20(3):173-176.
3. Alqahtani MQ. Tooth-bleaching procedures and their controversial effects: A literature review. Saudi Dent J.
2014;26(2): 33-46.
4. Cavalli V, Silva BG, Berger SB, Abuna G, Marson FC, Tabchoury C, et al. Effect of adhesive restoration and
bleaching technique on the concentration of hydrogen peroxide in the pulp chamber. Oper Dent.
2017;42(2):E44-E54.
5. Haywood VB. History, safety, and effectiveness of current bleaching techniques and applications of the
nightguard vital bleaching technique. Quintessence Int. 1992;23(7):471-88.
6. Joiner A. The bleaching of teeth: a review of the literature. J Dent. 2006;34(7):412-419.
7. Minoux M, Serfaty R. Vital tooth bleaching: biologic adverse effects-a review. Quintessence Int.
2008;39(8):645-659.
27. 8. Dahl JE, Pallesen U. Tooth bleaching--a critical review of the biological aspects. Crit Rev Oral Biol Med.
2003;14(4):292-304.
9. Elfallah HM, Bertassoni LE, Charadram N, Rathsam C, Swain MV. Effect of tooth bleaching agents on protein
content and mechanical properties of dental enamel. Acta Biomater. 2015; 20:120-128.
10. Menezes RP, Silva PD, Leal PC, Faria ESAL. Impact of 35% hydrogen peroxide on color and translucency changes in
enamel and dentin. Braz Dent J. 2018;29(1):88-92.
11. Yu H, Zhang CY, Wang YN, Cheng H. Hydrogen peroxide bleaching induces changes in the physical properties of
dental restorative materials: Effects of study protocols. J EsthetRestor Dent. 2018;30(2):E52-E60.
12. Hannig C, Duong S, Becker K, Brunner E, Kahler E, Attin T. Effect of bleaching on subsurface micro-hardness of
composite and a polyacid modified composite. Dent Mater. 2007;23(2):198-203.
13. Turker SB, Biskin T. Effect of three bleaching agents on the surface properties of three different esthetic restorative
materials. J Prosthet Dent. 2003;89(5):466-473.
14. Ismail EH, Kilinc E, Hardigan PC, Rothrock JK, Thompson JY, Garcia-Godoy C.Effect of two-minute application of
35% sodium ascorbate on composite bond strength following bleaching. J Contemp Dent Pract. 2017;18(10):874-880.
15. Briso AL, Rahal V, Sundfeld RH, dos Santos PH, Alexandre RS. Effect of sodium ascorbate on dentin bonding after
two bleaching techniques. Oper Dent. 2014;39(2):195-203.
28. 16. Danesh-Sani SA, Esmaili M. Effect of 10% sodium ascorbate hydrogel and delayed bonding on shear bond
strength of composite resin and resin-modified glass ionomer to bleached enamel.J Conserv Dent. 2011;14(3):241-
246.
17. Elmourad A, Alqahtani M. Effects of pre- and post-simulated home bleaching with 10% carbamide peroxide on
the shear bond strengths of different adhesives to enamel. The Saudi Journal for Dental Research. 2014;5(2):81-92.
18. Barcellos DC, Benetti P, Fernandes VV, Jr., Valera MC. Effect of carbamide peroxide bleaching gel concentration
on the bond strength of dental substrates and resin composite. Oper Dent. 2010;35(4):463-469.
19. Dudek M, Roubickova A, Comba L, Housova D, Bradna P. Effect of postoperative peroxide bleaching on the
stability of composite to enamel and dentin bonds. Oper Dent. 2013;38(4):394-407.
20. Cavalli V, de Carvalho RM, Giannini M. Influence of carbamide peroxide-based bleaching agents on the bond
strength of resin-enamel/dentin interfaces. Braz Oral Res. 2005;19(1):23-29.
21. Bagheri R, Fani M, Barfi Ghasrodashti A, Nouri Yadkouri N, Mousavi S. Effect of a home bleaching agent on the
fracture toughness of resin composites, using short rod design. J Dent (Shiraz). 2014;15(2):74-80.
22. Far C, Ruse ND. Effect of bleaching on fracture toughness of composite-dentin bonds. J Adhes Dent.
2003;5(3):175-182.
29. 23. Woo JM, Ho S, Tam LE. The effect of bleaching time on dentin fracture toughness in vitro. J EsthetRestor Dent.
2010;22(3):179-184.
24. Piemjai M, Lenglerdphol S. Effect of strong tooth-bleaching with 38% hydrogen peroxide on marginal seal of
dental restorations using self-etch and total-etch adhesives. J EsthetRestor Dent. 2018;30(2):153-159
25. Klein CA, Jr., da Silva D, Reston EG, Borghetti DL, Zimmer R. Effect of at-home and in-office bleaching on
marginal microleakage in composite resin restorations using two adhesive systems. J Contemp Dent Pract.
2018;19(3):248-252.
26. Mortazavi V, Fathi M, Soltani F. Effect of postoperative bleaching on microleakage of etch-and-rinse and self-
etch adhesives. Dent Res J (Isfahan). 2011;8(1):16-21.
27. Burke FJ, Hussain A, Nolan L, Fleming GJ. Methods used in dentine bonding tests: an analysis of 102
investigations on bond strength. Eur J ProsthodontRestor Dent. 2008;16(4): 158-165.
28. Hanabusa M, Mine A, Kuboki T, Momoi Y, Van Ende A, Van Meerbeek B, et al. Bonding effectiveness of a new
‘multi-mode’ adhesive to enamel and dentine. J Dent. 2012;40(6):475-484.
29. Perdigao J, Sezinando A, Monteiro PC. Laboratory bonding ability of a multi-purpose dentin adhesive. Am J
Dent. 2012;25(3):153-158. 30. McLean DE, Meyers EJ, Guillory VL, Vandewalle KS. Enamel bond strength of new
universal adhesive bonding agents. Oper Dent. 2015;40(4):410-417
30. 31. Perdigao J, Loguercio AD. Universal or multi-mode adhesives: why and how? J Adhes Dent. 2014;16(2):193-
194.
32. Perdigao J, Munoz MA, Sezinando A, Luque-Martinez IV, Staichak R, Reis A, et al. Immediate adhesive
properties to dentin and enamel of a universal adhesive associated with a hydrophobic resin coat. Oper Dent.
2014;39(5):489-499.
33. Perdigao J, Gomes G, Gondo R, Fundingsland JW. In vitro bonding performance of all-in-one adhesives. Part I–
microtensile bond strengths. J Adhes Dent. 2006;8(6):367-373.
34. Carvalho RM, Manso AP, Geraldeli S, Tay FR, Pashley DH. Durability of bonds and clinical success of adhesive
restorations. Dent Mater. 2012;28(1):72-86.
35. Kerby RE, Knobloch LA. Microtensile bond strength of one-step and self-etching adhesive systems. Oper Dent.
2005;30(2):195-200.
36. Pashley DH, Tay FR. Aggressiveness of contemporary selfetching adhesives Part II. Effects on unground enamel.
Dent Mater. 2001;17(5):430–440.
37. Tay FR, Pashley DH, King NM, Carvalho RM, Tsai J, Lai SC, Marquezini L., Jr Aggressiveness of self-etch
adhesives on unground enamel. Oper Dent. 2004;29(3):309-316.
31. 38. Perdigao J, Lopes MM, Lambrechts P, Leitao J, Van Meerbeek B, Vanharle G. Effects of a self-etching primer on
enamel shear bond strengths and SEM morphology. Am J Dent. 1997;10(3):141-146.
39. Shimada Y, Senawongse P, Harnirattisai MF, Nakaoki BY, Tagami J. Bond strength of two adhesive systems to
primary and permanent enamel. Oper Dent. 2002;27(4):403-409.
40. de Lima E, Santos R, Durao M, Nascimento A, Braz R. Universal cements: dual activated and chemically
activated. Acta BiomaterOdontol Scand. 2016;2(1):125-129.
41. Yazdi FM, Moosavi H, Atai M, Zeynali M. Dentin bond strength and degree of conversion evaluation of
experimental self-etch adhesive systems. J Clin Exp Dent. 2015;7(2):e243-249.
42. Jayasheel A, Niranjan N, Pamidi H, Suryakanth MB. Comparative evaluation of shear bond strength of universal
dental adhesives -an in vitro study. J Clin Exp Dent. 2017;9(7):e892-e896.
43. Poggio C, Scribante A, Della Zoppa F, Colombo M, Beltrami R, Chiesa M. Shear bond strength of one-step self-
etch adhesives to enamel: effect of acid pretreatment. Dent Traumatol. 2014;30(1):43-48.
44. Altunsoy M, Botsali MS, Sari T, Onat H. Effect of different surface treatments on the microtensile bond strength
of two self-adhesive flowable composites. Lasers Med Sci. 2015;30(6):1667-1673.
45. Shafiei F, Saadat M. Micromorphology and bond strength evaluation of adhesive interface of a self-adhering
flowable composite resin-dentin: Effect of surface treatment. Microsc Res Tech. 2016;79(5):403-407.
32. 46. Devarasa GM, Subba Reddy VV, Chaitra NL, Swarna YM. Self-etching adhesive on intact enamel, with and
without pre-etching. Microsc Res Tech. 2012;75(5):650-654.
47. Miyazaki M, Tsujimoto A, Tsubota K, Takamizawa T, Kurokawa H, Platt JA. Important compositional
characteristics in the clinical use of adhesive systems. J Oral Sci. 2014;56(1):1-9.
48. Gandhi G, Kalra JPS, Goyal A, Sharma A. Microphotographic assessment of enamel surface using self-etching
primer and conventional phosphoric acid: an in vitro study. Contemp Clin Dent. 2018;9(1):15-19.
33. EFFECT OF 35% SODIUM ASCORBATE ON MICROTENSILE BOND STRENGTH OF
COMPOSITE RESIN IMMEDIATELY AFTER BLEACHING
The application of 35% sodium ascorbate immediately
after bleaching effectively improved the bond strength
and was equal to the bond strength regained from the
one week delayed bonding
Ismail EH, Kilinc E, Hardigan PC, Rothrock JK, Thompson JY, Garcia-Godoy C.Effect of two-minute application of 35% sodium ascorbate on composite bond strength following bleaching. J
Contemp Dent Pract. 2017;18(10):874-880.
34. Effect of sodium ascorbate on dentin bonding after two bleaching techniques
ALF briso V rahal RH sundfeld PH dos santos RS alexandre
Briso AL, Rahal V, Sundfeld RH, Santos PD, Alexandre RS. Effect of sodium ascorbate on dentin bonding after two bleaching techniques. Operative dentistry. 2014
Mar;39(2):195-203.
thesis
Since the late 1800s, esthetic dentistry has become more widespread.
As early as 1848, reports showed evidence of chloride lime used as
nonvital tooth bleaching.1-3 Later, in 1864, the most effective technique for nonvital
bleaching was introduced by Truman, which used chlorine from a solution of calcium
hydrochlorite along with acetic acid
By the late 1800s, other bleaching agents
mentioned in the literature included aluminum chloride, oxalic acid, pyrozone,
hydrogen dioxide, sodium peroxide, sulphorus acid, sodium hypophosphate, chloride
of lime and cyanide of potassium.
In 1910, the use of 30% hydrogen peroxide was
first reported,1 and later in 1960, Klusmier reported in a study club a successful
attempt to bleach teeth using 10% carbamide peroxide utilizing a customized tray.
From the early 1800s until the early 1900s, approximately 40-60 articles were
published per year in the area of bleaching, debating about the efficiency of bleaching,
its indications, durability and above all, safety of the bleaching agent, and its effect on
tooth structure.1
REFERENCE: TRY TO FIND OUT SOFT COPY
Thesis
Cadenaro et al. explained that results of these
studies varied since different methods of analysis, different methods of preparation,
and different type and concentration of bleaching agents were utilized; 21 thus, the
controversy of whether bleaching agents alter the morphology of tooth structure is
not completely determined.
In recent years, the demand for tooth bleaching has increased because people are more concerned about improving the aesthetic appearance of their smile, and clinicians are considering more conservative, noninvasive dental treatments. Many studies in the literature have described various tooth bleaching approaches using different bleaching materials, concentrations, and lightactivation techniques.1 Dental bleaching can be divided into vital and non-vital tooth bleaching. The three main vital tooth-bleaching protocols include home bleaching, in-office bleaching, and over-the-counter bleaching agents.
In recent years, the demand for tooth bleaching has increased because people are more concerned about improving the aesthetic appearance of their smile, and clinicians are considering more conservative, noninvasive dental treatments. Many studies in the literature have described various tooth bleaching approaches using different bleaching materials, concentrations, and lightactivation techniques.1 Dental bleaching can be divided into vital and non-vital tooth bleaching. The three main vital tooth-bleaching protocols include home bleaching, in-office bleaching, and over-the-counter bleaching agents.
However, since the bleaching material is held in intimate contact with the teeth and any associated restorations, this may cause undesirable effects on the natural tooth structure,9,10 bonding interface, and restorative materials, such as softening and degradation of the teeth and restorative materials
Other studies evaluated the effects of bleaching on pre-existing bonded restorations using a variety of methods, including bond strength measurements,17-20 fracture resistance measurements,21-23 and leakage analyses.24-
Nevertheless, only a few studies have investigated the effect of bleaching materials on the bond strength and stability of pre-existing resin composite restorations. The stability of bonded resin composite restorations to tooth structure plays an important role in determining the durability of these restorations
The samples were
randomly divided into two main groups (n = 50 teeth
per group), namely the control (non-bleach) group and
the postoperative bleaching group. Each group was then
subdivided into five subgroups depending on the type
of adhesive utilized (n = 10 teeth per subgroup). The five
adhesives were as follows:
. To ensure proper condensation of the composite, the material was placed in the tube in the silicone mold, overfilled, and then pressed with a glass slab before being light-cured for 20 seconds. Following this, the silicone mold was gently removed, and the excess composite was trimmed with a plastic instrument. Manufacturer’s instructions were followed in all bonding procedures (Table 1). An Elipar S10 LED curing light (3M ESPE Dental Products) was used to perform the light-curing procedures, with a light power density of 1000 mW/cm2 , which was examined regularly using a Bluephase Meter II radiometer
Subsequently, the specimens in the control (nonbleach)
group underwent shear bond testing. For the
postoperative bleaching group, a carbamide peroxide
bleaching material (Opalescence PF 20%; Ultradent®
Products, Inc., South Jordan, UT, USA) was applied on
each specimen’s bond interface daily for 14 consecutive
days to simulate the home bleaching technique (Fig. 1B).
The bleaching gel was placed on the specimen each day
for 4 hours; the specimens were subsequently washed
under running water to remove the bleaching gel
completely, followed by storage in artificial saliva at 37°
C. After the 14-day bleaching treatment, the specimens
were subjected to shear bond testing.
multiple comparison tests between
different pairs of adhesive materials demonstrated that
the mean shear bond strength values of the TNB-TE
and SB-TE adhesives were significantly higher than
were those of the other three adhesives, whereas the
mean shear bond strength value of the OB adhesive was
significantly lower than were those of the other four
adhesives
Optibond total etch
mean shear bond strength values of the TNB-TE and
SB-TE adhesives were significantly higher than were
those of the other three adhesives (OB, SB-SE, and TNBSE),
whereas the mean shear bond strength values of
the OB, SB-SE, and TNB-SE adhesives were significantly
lower than were those of the TNB-TE and SB-TE adhesives
The current research tested the effect of postoperative home bleaching using 20% carbamide peroxide on the shear bond strengths of different adhesives to enamel. The results showed that the bleaching procedure reduced the mean bond strength values of all five tested dental adhesives (OB, SB-TE, SB-SE, TNB-TE, and TNB-SE) and reduced the stability of resin composite-enamel bonds. Therefore, the main hypothesis of this study, stating that bleaching with 20% carbamide peroxide would not reduce the shear bond strength values of different adhesive systems to enamel surface and would not affect the stability of resin composite-enamel bonds, was rejected.
In this study, the home bleaching protocol was performed using 20% carbamide peroxide.3 This concentration was used because it is considered a safe and effective home bleaching treatment.5 However, dental bleaching agents must come in close contact with the tooth surface and must penetrate and react with the dental substrate. This reaction is not specific, and, because bleaching products contact the teeth and dental restorations for extended periods of time, especially during home bleaching treatments, the bleaching agents may cause undesirable effects on both the tooth structure and restorative materials.4 The current study demonstrated that bleaching significantly reduced the shear bond strength values of the five tested adhesive materials when compared with the values of the unbleached specimens
In the present study,
two universal adhesives were used, namely the SB and
TNB adhesives. Both adhesives were applied using
the TE and SE techniques. The results of the current
study revealed that the mean bond strength values
of TE adhesives (TNB-TE and SB-TE) on unbleached
enamel were significantly higher than were those of SE
adhesives (TNB-SE and SB-SE) and the OB adhesive,
with no significant differences in the bond strength
values between the TNB-TE and SB-TE adhesives or
between the OB and SB-SE adhesives. These results
agree with those of many previous studies reporting
that stable resin composite bonding to enamel was
achieved using etch-and-rinse adhesives and less
This combination of properties
permits the TNB adhesive to dependably bridge the
gap between the hydrophilic tooth structure and the
hydrophobic restorative resin material under various
surface conditions
Here, the bond strength values for the OB adhesive
were not significantly different from those for the SB-SE
adhesive in the control (non-bleach) and postoperative
bleaching groups.
especially
with SE adhesives with no pre-existing stable adhesive
bond strength.
Discussion:
Total etch single bond 2
On the other hand, the results of the current study disagree with the results of other studies demonstrating that bleaching treatment significantly decreased the bond strength values of SE adhesives but not of TE adhesives to enamel.17,20 The discrepant results might be explained by the use of higher concentration of bleaching material in the current and the other consistent studies which could have caused damaging effects on both TE and SE adhesives, particularly on the SE adhesives.
Discussion:
The effects of bleaching were confirmed in the SEM analysis, as the bonded interface of the resin composite posts exhibited poor adaptation with all tested adhesives in the bleached vs. unbleached specimens, and gaps and irregular interface margins were observed in the bleached specimens. The major failure mode in the postoperative bleaching group for all tested adhesives was an adhesive failure. Both SEM testing and failure analysis findings for the postoperative group indicated that the bonded interface was the weakened zone of the adhesive bond and was the most vulnerable to deterioration by the bleaching process.
The major failure mode for all of the tested adhesives in the control group was the mixed type. Both SEM testing and failure analysis findings for the control group can be attributed to the stable and reliable bond strength of the tested adhesives, especially TNB-TE and SB-TE
Many studies have examined the reduced bond strengths of bonded restorations to enamel and dentin following tooth bleaching procedure.