Effect of different cleansing methods on the artificially aged bond strength of resin to contaminated zirconia: A systematic review.

PURPOSE: The aim of this review was to evaluate studies investigating the effect of cleansing methods on the artificially aged bond strength of resin to contaminated zirconia restorations and determine which cleansing method of contaminated zirconia for resin bonding improvement is more efficient. METHODS: An electronic search of published studies in English language was carried out until July 2021 on Scopus, Web of Science, and Medline databases. Data from in vitro studies involving the evaluation of the artificially aged bond strength of resin to contaminated zirconia following different cleansing methods were included. In vitro studies in which samples were not subjected to at least 5000 thermocycles, were excluded. RESULTS: Of 162 articles retrieved initially, 19 were eligible to be included in the systematic review, of which 5 articles were excluded. Therefore, the final sample was 14 in vitro studies. All of the included studies for air abrasion suggested this method as an effective cleansing method, but 6 of 8 included studies reported cleaning paste (Ivoclean) as an effective cleansing method. All of the included studies for NaOCl and a cleaning gel (AD Gel) reported their efficacy. Finally, the results of included studies showed the ineffectiveness of phosphoric acid, water, isopropanol, enzymatic detergents, hydrogen peroxide, and acetone. CONCLUSIONS: Air abrasion has been reported as an effective cleansing method to improve the bond strength of resin to contaminated zirconia. To improve the effectiveness of cleaning paste in resin bonding, another efficient cleansing method should be followed after this method. However, the superior cleaning potential of air abrasion rather than cleaning paste has been reported. Sodium hypochlorite and cleaning gel seem to be as effective as air abrasion, but extensive water-rinsing is necessary after the application of these cleaning agents.

Call for ACTion: Transforming Dental Education at the University of North Carolina at Chapel Hill.

The University of North Carolina at Chapel Hill Adams School of Dentistry is developing a transformative curriculum that prepares students to enter contemporary practice. The Advocate, Clinician, and Thinker (ACT) framework will provide the basis for developing a resilient workforce capable of meeting emerging health care needs over the next 40 years.

Effect of composite type and placement technique on cuspal strain.

OBJECTIVE: To compare the cuspal strain in Class II restorations made with bulk-fill and conventional composite resins. MATERIALS AND METHODS: Fifty extracted maxillary premolars were mounted into phenolic rings and divided into five groups (n = 10). Specimens received standardized MOD preparations. A two-step self-etch adhesive was applied and the preparations were restored using a custom matrix as follows: Filtek Supreme Ultra in eight 2-mm increments (FSUI); Filtek Supreme Ultra in bulk (FSUB); SonicFill in bulk (SF); SureFil SDR flow in bulk, covered with a 2-mm occlusal layer of Filtek Supreme Ultra (SDR/FSU); Tetric EvoCeram Bulk Fill in bulk (TEBF). Strain gages bonded to the buccal and lingual cusps recorded cuspal strain during restorations. End strain values were determined and data were subjected to Kruskal-Wallis testing, followed by one-way ANOVA and Tukey´s post hoc test. RESULTS: Combined strain values and standard deviations (in µÉ›) were: FSUI: 723 ± 102.8, FSUB: 929.2 ± 571.9, SF: 519.1 ± 80.2, SDR-FSU: 497.4 ± 67.6 and TEBF: 604.5 ± 127.1. A significant difference was found between group FSUI and groups SF, SDR-FSU, and TEBF. Group FSUB showed significantly higher mean strain and greater standard deviation than all other groups due to cuspal fractures, and was thus excluded from the statistical analysis. CONCLUSIONS: The tested bulk-fill composite resins exerted less strain onto tooth structure than the incrementally placed conventional composite resin, although the magnitude of generated strain was product-dependent. Bulk-filling with conventional composite resins is contraindicated. CLINICAL SIGNIFICANCE: Bulk-fill composite resins exerted less strain onto adjacent tooth structure than a traditional composite, even when that composite is was placed incrementally. Bulk-filling with traditional composite resins is unpredictable and contraindicated.

Effect of finishing technique on the occurrence and length of microcracks in resin-based materials.

PURPOSE: To evaluate the presence and length of microcracks in resin-based materials finished with different techniques, using optical coherence tomography (OCT). METHODS: Standardized Class V preparations (3x2x2mm) were made in the facial and lingual surfaces of 20 recently-extracted human third molars. 20 preparations were restored with a resin-based composite material (RBC; Filtek Supreme Ultra) and the other 20 with a resin-modified glass-ionomer material (RMGI; Ketac Nano). After final polymerization, specimens were further stratified by finishing system: aluminum oxide discs (Sof-Lex) or spiral fluted carbide bur series (H48L). By random allocation, each extracted tooth therefore received one RBC and one RMGI restoration, and equal numbers of restorations from each material were finished using each finishing system (n= 10). After 24 hours of storage in 100% humidity at room temperature, the specimens were evaluated at x20 to x600 under environmental SEM. Cross-sectional occlusal-cervical B-mode images were obtained in increments of 25 mm from the mesial margin to the distal margin of the restoration using a spectral-domain (SD) OCT system and analyzed using Image J software to identify and measure microcrack penetration into each restoration. The total length (mm) at the point of the deepest microcrack penetration in each specimen was recorded. Data were statistically analyzed using a t-test. RESULTS: No microcracks were observed in the RBC samples. However, microcrack presence was identified in all of the RMGI specimens. The t-test showed a statistically significant difference (P< 0.05) in mean microcrack length values based on the finishing technique used for the RMGI samples. [SofLex: 0.67 (± 0.28) mm; carbide: 1.26 (± 0.30)] mm. Two-way ANOVA showed significant differences in the factors "finishing technique" and "restorative material" (P< 0.001). The interaction of these two factors was also statistically significant (P< 0.001). For the tested RMGI, Tukey post-hoc test revealed that the finishing with aluminum oxide groups resulted in statistically significant lower mean microcrack length when compared to spiral fluted carbide burs (P< 0.001). CLINICAL SIGNIFICANCE: Resin-modified glass-ionomer (RMGI) is more susceptible to microcrack presence than resin-based composites. Also, aluminum oxide discs produced lower values of mean microcrack length than spiral fluted carbide burs after the finishing procedure of RMGI restorations.

Critical Appraisal: Bulk-fill Composites, Part I.

The Journal of Esthetic and Restorative Dentistry published a Critical Appraisal of bulk-fill flowable composite resins by Dr. Ricardo Walter in early 2013 (JERD 2013;25(1):72-6). Since then, new bulk-fill composite options have become available and have rapidly achieved great popularity. This two-part Critical Appraisal reviews some of the more recent information on the various bulk-fill options.

Critical appraisal. Evidence for sealing versus restoration of early caries lesions.

Resin-based pit and fissure sealants are established tools for prevention of dental caries. Conversely, the role of sealants for management of existing early dental caries lesions has been disputed despite the recommendation from the American Dental Association Council on Scientific Affairs. The development of more sensitive caries detection technologies has revealed that many sealants have likely been placed over incipient lesions inadvertently over the years. However, the issue remains whether sealing overt incipient occlusal caries lesions leads to a worse outcome versus restoring the surface. Certainly, there are diverse opinions regarding this topic. But what does the science say? This Critical Appraisal presents evidence from several clinical trials for sealing incipient occlusal caries lesions.

Effect of dentin conditioning on bond strength of fiber posts and dentin morphology: a review.

PURPOSE: Post and core systems are commonly used to restore endodontically treated teeth. A durable bond between fiber posts and dentin contributes to the success of the restorative treatment. Different irrigants are used during post space preparation and various studies have investigated the effects of these chemical agents on bond strength and dentin morphology. METHODS: The MEDLINE-PubMed, Cochrane, and SCOPUS databases were searched for appropriate papers addressing the effects of irrigants on bonding of fiber posts to dentin and on dentin morphology. Databases were searched from 2002 through 2012. The search was performed using a variety of keywords including fiber posts, bond strength, post space preparation, post space irrigation, and smear layer removal. RESULTS: Using multiple key words and different strategies, 68 publications were initially screened. The abstracts of these 68 publications were scanned for relevance, and 50 full-text articles were selected and read in detail. Thirty publications which discussed the effect of various intracanal irrigants on bond strengths of fiber posts and dentin morphology were incorporated in this review. Following review of all relevant papers, it can be concluded that bond strengths of fiber posts to radicular dentin can be affected by the irrigants used and that various irrigants affect different types of resin cements differently.

Critical appraisal. In-office tooth whitening: pulpal effects and tooth sensitivity issues.

In-office bleaching is an effective method for whitening teeth.Tooth sensitivity associated with in-office whitening is reversible and may range from mild to considerable. The incidence and severity of tooth sensitivity can be reduced by pretreatment with a desensitizer such as potassium nitrate. Histologic studies and clinical studies on long-term pulpal effects are lacking to definitively support the safety of in-office tooth whitening. Future studies on the etiology of tooth sensitivity related to whitening might greatly improve the means of preventing and managing this side effect.

Current strategies in dentin remineralization.

Partial caries removal procedures are used clinically in an attempt to conserve tooth structure and prevent pulp damage. Within this approach, the caries-infected dentin is removed, and the partially demineralized caries-affected dentin is preserved and sealed with materials that enhance remineralization. Fluoride-releasing glass ionomers have been commonly used for this purpose. Recent studies have shown potential for other cements and bioactive adhesive materials to promote dentin repair through various strategies. These strategies include ion releasing of Ca-P and the guided tissue remineralization or biomimetic remineralization of dentin. The latter is potentially useful in the remineralization of the demineralized acid-etched dentin that is incompletely infiltrated by adhesives in dentin bonding. The purpose of this Critical Appraisal is to provide the clinician with a summary of current literature that clarifies understanding of the process of dentin remineralization and to describe current strategies in this area.

Critic appraisal. Postoperative sensitivity with indirect restorations.

Postoperative sensitivity is characterized by short and sharp pain, and often experienced after cementation of indirect restorations. Factors associated with the occurrence of post-cementation sensitivity include type of cement, removal of smear layer by acid-etching, aggressive tooth preparation, inadequate provisional restorations, and patient's age. Its prevention is based on either interfering with mechanoreceptor activity or occluding the dentinal tubules. Regarding the latter, application of dentin desensitizers may be effective for blocking the tubules and significantly reducing dentin permeability and consequently postoperative sensitivity. This Critical Appraisal will present available clinical data where traditional materials such as zinc phosphate and glass ionomer cements (GIC) as well as self-adhesive resin-based cements were used.

Critical appraisal: Cross-linkers and the dentin matrix.

The formation of a hybrid layer is essential for successful dentin bonding and is achieved by adhesive penetration between exposed collagen fibrils in the demineralized dentin. Incomplete infiltration of the adhesive within the collagen network results in exposed fibrils, which may suffer enzymatic degradation over time. Methods to increase collagen resistance to proteinases (enzymes that degrade proteins) have been studied. One particular approach is to use collagen cross-linking agents that modify collagen through addition of specific or random amino acid linkage between and within its molecules. This Critical Appraisal provides information on the effects of various cross-linkers on dentin collagen stability, dentin properties, and resin-dentin bond strengths, and calls for critical thinking on the potential effects of this therapeutic approach.

Three-year clinical evaluation of a silorane composite resin.

STATEMENT OF PROBLEM: Composite resins are still outperformed by amalgams in the clinical practice with secondary caries and fractures being their most common failures. A material that suffers less polymerization shrinkage might improve the clinical performance of composite resins. PURPOSE: To evaluate the clinical performance of a low-shrink silorane-based composite resin (Filtek LS Low Shrink Posterior Restorative, 3M ESPE, St. Paul, MN, USA) in comparison with a methacrylate-based composite resin (Tetric EvoCeram, Ivoclar Vivadent, Schaan, Principality of Liechtenstein) over time. MATERIALS AND METHODS: Candidates in need of Class II composite resin restorations participated in this randomized controlled clinical trial. Those were 25 female and six male subjects with average age of 44.3 ± 12.7 years. Participants received 82 restorations, being 54 in premolars and 28 in molars. Procedures, which included the restoration of primary caries lesions or replacement of failing restorations, were done using modified preparations with no bevels or additional retention. Restorations were placed using Filtek LS (and dedicated self-etch adhesive) or Tetric EvoCeram (with AdheSE, Ivoclar Vivadent), following manufacturers' instructions. Incremental placement technique was applied and the restorations were immediately finished. Follow-up evaluations occurred at six, 12, 24, and 36 months and were done using the Fédération Dentaire Internationale criteria. Statistical analysis was performed using generalized estimating equations. RESULTS: The recall rate at 36 months was 89%. All interaction terms were not significant. CONCLUSIONS: Filtek LS performs as well as Tetric EvoCeram performs in the clinical setting at 36 months. CLINICAL SIGNIFICANCE: The silorane-based composite resin Filtek LS and the conventional methacrylate-based composite resin Tetric EvoCeram performed similarly well in posterior restorations over at least 36 months of clinical service.

Effect of surface treatments on fracture resistance of root filled teeth with bonded fibre posts.

BACKGROUND/AIM: This study examined the effect of several dentin surface treatments on fracture resistance of root filled teeth containing bonded fibre posts. MATERIAL AND METHODS: The roots of 84 single-canal premolars were instrumented, filled with gutta-percha and randomly divided into seven groups. The coronal 9 mm of gutta-percha was removed to create a post space. In the experimental groups, canals were irrigated with distilled water, 37% phosphoric acid, 5% sodium hypochlorite, 17% EDTA, 5% sodium hypochlorite followed by 17% EDTA or 5% sodium hypochlorite followed by 10% ascorbic acid. Fibre posts were cemented using Panavia F2.0 resin cement, and the specimens were mounted in acrylic resin blocks. Following 1-week storage in an incubator, specimens were thermocycled and their fracture resistance was determined using a universal testing machine. Data were analysed using the Kruskal-Wallis test. RESULTS: Mean fracture resistance values ranged from 465.8 N in specimens treated with sodium hypochlorite and ascorbic acid to 739.1 N for those treated with sodium hypochlorite only. However, differences in fracture resistance were not statistically significant (P = 0.114). CONCLUSIONS: None of the surface treatments improved vertical fracture resistance of root filled teeth containing bonded fibre posts.

Critical appraisal: dental amalgam update­part I: clinical efficacy.

Dental amalgam use has been controversial ever since the Crawcour brothers of France introduced amalgam to the United States in 1833. It has been criticized for its alleged clinical shortcomings and biologic effects. As a result, we thought that it would be useful to provide an update on dental amalgam in two parts. Part I, presented here, focuses on the clinical aspects of dental amalgam, whereas Part II will focus on dental amalgam's biologic effects.

Critical appraisal: post-op sensitivity with direct composite restorations.

Sales of self-etch adhesive systems have grown considerably over the last 10 to 12 years. One of the most important factors contributing to this growth is the perception that self-etch adhesives cause less postoperative sensitivity than etch-and-rinse adhesives. Certainly, there is much anecdotal evidence supporting this perception. But what does the science say? This Critical Appraisal presents evidence from several clinical trials of postoperative sensitivity in posterior composite restorations.

Critical appraisal: dental amalgam update--part II: biological effects.

Dental amalgam restorations have been controversial for over 150 years. In Part I of this Critical Appraisal, the clinical efficacy of dental amalgam was updated. Here in Part II, the biological effects of dental amalgam are addressed.

Critical appraisal: approaches to caries removal: what the clinical evidence says.

Every day in the United States, complete caries removal in vital, asymptomatic teeth with deep carious lesions ends in unavoidable exposure of the pulp. As a result, the complexity and cost of treatment increases dramatically and many patients are left with extraction as their only viable option. This review appraises evidence which supports alternative treatments designed to preserve the vitality of the tooth and thus avoid extraction.

Tooth whitening in the orthodontic practice: a survey of orthodontists.

INTRODUCTION: The demand for tooth whitening has grown almost exponentially in the last 20 years, but there are no published reports regarding how bleaching is used in contemporary orthodontic practices in the United States. METHODS: A weighted sample of American Association of Orthodontists members (3601) was surveyed via electronic and paper questionnaires to quantitatively, by logistic regression, and qualitatively assess orthodontists' current practices regarding tooth-whitening procedures. RESULTS: Of the surveys, 1222 were completed, and 1182 surveys were eligible for analysis. Nationwide, 88.8% of orthodontists had patients who requested tooth whitening, and 76.2% of orthodontists had recently recommended whitening procedures for some patients, typically less than 25% of their total patient population. Approximately a third (32.8%) of orthodontists provided whitening, and nearly two thirds (65.8%) referred whitening procedures to other dental professionals. The geographic region of the country had a statistically significant effect on the proportion of orthodontists who received whitening requests (P = 0.004), recommended whitening procedures (P <0.0006), and provided whitening services in their specialty practices (P <0.0001). CONCLUSIONS: Almost all orthodontists encounter patients who request whitening procedures, and most recommend whitening procedures for a small percentage of their patients. The proportion of orthodontists who refer such procedures to other providers is nearly double the proportion that provides them.

Developing entrustable professional activities for general dentistry at the University of North Carolina.

INTRODUCTION: As part of curriculum innovation, the University of North Carolina (UNC) Adams School of Dentistry identified core entrustable professional activities (EPAs) that graduates must demonstrate for practice readiness. This paper describes the development of the UNC EPAs and the perceptions of the general dentistry faculty. METHODS: Upon establishing a blueprint of knowledge, skills, and attitudes of UNC graduates, using a distributed leadership approach, faculty teams developed EPAs focused on the patient care process. The American Dental Education Association Compendium of Clinical Competency Assessments and Commission on Dental Accreditation Standards informed the team's work. Perceptions of the assessment framework were examined using a questionnaire completed by 13 general dentistry faculty considering the importance, accuracy, and agreement of each EPA, associated domains of competence, and encounter management on a 6-point rating scale. RESULTS: Distributed leadership was a useful strategy in EPA development to disperse decision-making and build ownership. Through multiple iterations, four EPAs (assessment, plan of care, collaborative care, and provision of care) with associated sub-EPAs emerged. EPAs included a description, required knowledge and skills, and rubrics for assessment. The general dentistry faculty reported a high level of importance, accuracy, and agreement with EPAs, domains of competence, and encounter management. DISCUSSION: EPAs provide a standardized manner to describe the comprehensive work dentists perform, shifting away from individual competencies. The UNC EPAs provide the foundation for longitudinal measures of competence preparing graduates for independent practice. With limited EPAs frameworks available in dentistry, we aim to inform the development and implementation of EPAs across dental education.

Influence of tooth age and etching time on the microtensile bond strengths of adhesive systems to dentin.

PURPOSE: 1. To evaluate the effect of tooth age on the microtensile bond strengths (µTBS) of various adhesive systems to dentin; 2. To evaluate the effect of different etching times on the microtensile bond strengths of different adhesive systems to young vs mature dentin. MATERIALS AND METHODS: One hundred twenty intact human teeth were mechanically ground to expose midcoronal dentin and were randomly assigned to three groups (n = 40) according to subjects' age in years: 15 to 25, 35 to 45, and >= 55. Within each group, specimens were further randomized into 8 subgroups according to adhesive (etch-and-rinse 3- and 2-step; self-etching 2- and 1-step) and etching time (manufacturer instructions vs extended). Resin composite was applied to the treated surfaces, and after 24 h, all specimens were processed for microtensile bond strength testing. Data were analyzed by factorial ANOVA and Tukey's test (p = 0.05). RESULTS: µTBS values ranged from 10.9 MPa (2-step self-etching, extended etching time, age group 15 to 25) to 50.7 MPa (1-step self-etching, extended etching time, age group >= 55). With only one exception, tooth age and etching time had no significant effect on the bond strengths of the adhesives to dentin. The 2-step self-etching system had lower bond strengths than the other systems, regardless of etching time or tooth age. CONCLUSION: Tooth age and etching time did not affect the dentin bond strengths of the adhesives tested.