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OBJECTIVES: This study examined the in vitro fatigue resistance of maxillary premolars with 2 mm or 3 mm preserved cusp thicknesses restored with lithium disilicate onlays. MATERIALS AND METHODS: Premolars(N = 48) were divided into six groups. Onlays for groups 1 to 4 preserved a 3 mm functional (G1), 2 mm functional (G2), 3 mm nonfunctional (G3), or 2 mm nonfunctional (G4) buccal-lingual cusp width. Onlays for group 5 (G5, control) replaced both cusps. Group 6 (G6) samples were identical to G1 with added retentive boxes. Lithium disilicate onlays were exposed to thermocycling (10 000 cycles, 5°C-55°C, 30s/cycle) and mechanical loading (1.2 million cycles at 1.4 Hz and 70 N). All samples were examined for onlay debonding or cusp or onlay fracture. RESULTS: Failure rates were 75%(G1), 0.0%(G2), 12.5%(G3), 0.0%(G4), 0.0%(G5), and 0.0%(G6). The difference in percent failure between the groups preserving the functional cusps (37.5%) and the groups preserving the nonfunctional cusps (6.3%) was statistically significant (P = .04; 95%CI:2.11-55.66). No cusp or restoration fractures were observed; all failures were due to debonding of the restoration. CONCLUSION: Teeth with thin remaining cusps that were restored with bonded lithium disilicate onlay restorations were not prone to fracture. Retentive preparation features that physically eliminated lateral displacement prevented onlay debonding even though the ceramic-enamel margin was directly at the occlusal contact. CLINICAL SIGNIFICANCE: The use of adhesively retained lithium disilicate ceramic onlays may be a viable alternative to full coverage restorations and may challenge traditionally accepted principals related to preparation resistance and retention form of ceramic partial coverage restorations.

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PURPOSE: To evaluate the survival rate (fatigue resistance), bonding efficiency and marginal integrity of monolithic zirconia partial and full coverage single restorations adhesively bonded to the tooth structure using air-particle abrasion, a primer with 10-methacryloyloxydecyl dihydrogen phosphate and a composite-resin cement (APC) protocol. MATERIALS AND METHODS: Extracted human premolars (N = 32) were randomly divided into four groups of eight specimens each. Premolars were prepared for the following restorations: full crown (group 1, control), mesial-occlusal-distal-facial onlay (MODF, group 2) preserving 2 mm facio-lingual functional cusp width, mesial-occlusal-distal-lingual onlay (MODL, group 3) preserving 2 mm facio-lingual nonfunctional cusp width, mesial-occlusal-distal-buccal-lingual onlay (MODBL, group 4), overlay preparation. All restorations were milled from monolithic 3 mol% yttria (3Y) zirconia blocks (ZirCad, A1 LT, Ivoclar Vivadent) with CAD/CAM software presets at minimum occlusal and axial thicknesses of 1 mm. The intaglio surface of the restorations was air-particle abraded (50 µm Al2 O3 , 2-Bar pressure, 15 s, 10 mm distance) and primed. An adhesive cement system was used to bond the restorations. Each group was subjected to thermomechanical loading for 1.2 million cycles (force = 70 N, 1.4 Hz) with simultaneous thermocycling (5-55°C, 30 s dwell time) using a mastication simulator. All specimens were examined under scanning electron microscope (SEM) analysis (30, 100, and 150×) to evaluate cracks and marginal defects. Fracture of restoration and/or fracture within tooth structure, and debonding were considered modes of failure. RESULTS: One specimen from group 2 debonded at 632,000 cycles. None of the specimens failed due to fracture. SEM analysis at 30× indicated marginal integrity issue of the remaining seven intact specimens of group 2 in the area of antagonist contact. No specimens from group 1, 3, and 4 demonstrated marginal integrity issue at 30×. None of the specimens demonstrated any microcrack at 100× and150×. CONCLUSIONS: Due to its fatigue resistance, 3Y-zirconia is a viable option for partial and full coverage single restorations. Following a strict bonding protocol, zirconia demonstrated durable adhesion to the tooth structure. Occlusal contact on restoration margins should be avoided.

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STATEMENT OF PROBLEM: A direct relationship has been reported between yttria concentration and translucency in zirconia restorations. However, increased yttria concentration also increases the cubic phase of the zirconia, which reduces its strength. The effect of increased yttria content on the fracture resistance of zirconia as a function of material thickness after fatigue testing requires evaluation. PURPOSE: The purpose of this in vitro study was to use the biaxial flexural test to evaluate the effect of yttria concentration on the mean fracture load (N) before and after fatiguing and thermocycling as a function of zirconia thickness. MATERIAL AND METHODS: Disk-shaped specimens of 5 mol% yttria partially stabilized zirconia (5Y-PSZ, BruxZir Anterior Solid Zirconia) and 3 mol% yttria partially stabilized zirconia (3Y-PSZ, BruxZir Shaded Zirconia) were prepared to thicknesses of 1.2 and 0.7 mm. For each thickness, the biaxial flexural test was used to measure the fracture load (N) before and after fatigue testing, with 1.2 million cycles at a 110-N load and simultaneous thermocycling at 5 °C to 55 °C (n=20). The data were analyzed by repeated-measures ANOVA (α=.05). RESULTS: Yttria concentration, thickness, and exposure to fatiguing had a statistically significant effect on the mean biaxial flexural load (yttria concentration: P<.001; thickness: P<.001; fatiguing: P=.004 for the 3Y-PSZ). One of the major findings in this study was that 30% of the 1.2-mm-thick 5Y-PSZ specimens and 80% of the 0.7-mm-thick 5Y-PSZ specimens fractured during fatiguing. All specimens of the 3Y-PSZ groups survived the fatiguing protocol. The 3Y-PSZ groups had statistically significant higher flexural loads than the 5Y-PSZ groups. The 1.2-mm thickness groups had statistically significant higher flexural loads than the 0.7-mm thickness groups. CONCLUSIONS: Yttria concentration had a significant effect on the strength of zirconia. 5Y-PSZ was considerably less resistant to fracture before and after fatigue testing than 3Y-PSZ. Decreasing the thickness of zirconia reduces its fracture resistance, regardless of the zirconia type.

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PURPOSE: To compare the performance of universal adhesives containing different monomers, namely 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) and dipentaerythritol penta-acrylate monophosphate (PENTA), in the restoration of non-carious cervical lesions (NCCLs). METHODS: This was a randomized controlled clinical trial involving 63 subjects in need of restorations of 203 NCCLs. Notch-shaped lesions were restored with Kalore (GC Corporation) after application of Scotchbond Universal (SU) or Prime&Bond Elect (PBE) following the etch-and-rinse (ER) or self-etch (SE) technique. Restorations were assessed after 1 week, 18 and 36 months. Logistic regression was performed for each outcome separately with compound symmetric variance-covariance structure assumed to consider a correlation of restorations within subjects. All analyses were conducted using SAS 9.4 (SAS). RESULTS: 150 teeth in 41 subjects were assessed at 36 months. Three restorations in the PBE_SE group failed the retention criterium. Statistically significant differences were reached for the following comparisons: restorations with SU_SE were 75% less likely to maintain a score of Alfa for marginal discoloration than PBE_SE; restorations with PBE_SE were 83% less likely to maintain a score of Alfa for marginal adaptation than PBE_ER. CLINICAL SIGNIFICANCE: More than 20% of restorations restored with universal adhesives developed marginal degradation after 36 months. The impact of phosphoric acid on the restoration seems to be material-dependent.

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STATEMENT OF PROBLEM: Translucent zirconia has been marketed to dentists seeking to provide esthetic monolithic dental restorations. Evidence on differences in translucency between recently introduced translucent zirconia and conventional zirconia before and after fatigue testing with thermocycling is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effect of fatiguing and thermocycling on the translucency of 5 mol% yttria partially stabilized zirconia (5Y-PSZ) and 3 mol% yttria partially stabilized zirconia (3Y-PSZ) at clinically relevant thicknesses. MATERIAL AND METHODS: Translucent zirconia (BruxZir Anterior Solid Zirconia [5Y-PSZ]) and conventional zirconia (BruxZir Shaded Zirconia [3Y-PSZ]) were evaluated. Disk-shaped specimens were prepared to 0.7-mm and 1.2-mm thicknesses for each zirconia type. Four groups (n=10/group) were evaluated. Translucency parameter (TP), contrast ratio (CR), and light blockage percentage (Lb%) were recorded by using an integrating sphere spectrophotometer before and after fatiguing (1.2 million cycles at 110-N load with simultaneous thermocycling at 5 °C to 55 °C). Data were analyzed by repeated-measures analysis of variance for statistical significance (α=.05). CR values were compared with the reported 0.06 translucency perception threshold of the human eye. RESULTS: A statistically significant difference was found in TP, CR, and Lb% between 5Y-PSZ and 3Y-PSZ (P<.001). Thickness had a statistically significant effect on TP, CR, and Lb% (P<.05). The 0.7-mm thickness groups were more translucent and had lower Lb% than the 1.2-mm thickness groups (P<.001). Baseline ranking from most to least translucent according to TP and CR measurements was as follows: 5Y-PSZ (0.7 mm), 3Y-PSZ (0.7 mm), 5Y-PSZ (1.2 mm), and 3Y-PSZ (1.2 mm). Lb% was 64% at the 1.2-mm and 56% at the 0.7-mm thickness in the 3Y-PSZ groups. Lb% was 61% at the 1.2-mm and 53% at the 0.7-mm thickness in the 5Y-PSZ groups. None of the groups, before and after fatiguing, had a CR value exceeding the clinically perceivable 0.06 translucency perception threshold value. CONCLUSIONS: Translucent (5Y-PSZ) and conventional (3Y-PSZ) zirconias evaluated in this study displayed degrees of translucency that were inversely related to the zirconia thickness. 5Y-PSZ was more translucent and blocked less light than 3Y-PSZ, but this difference may not be perceivable to the human eye. Both 5Y-PSZ and 3Y-PSZ were optically stable after fatiguing and thermocycling.

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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.

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The aims of this study were to identify the level of interexaminer agreement among preclinical operative dentistry faculty members when grading Class II preparations performed by first-year dental students; to develop discrimination exercises for specific preparation components where interexaminer agreement was poor; and to evaluate if the discrimination exercises were able to improve inter- and intraexaminer agreement. In the preliminary phase of this study, 13 components of 32 Class II cavity preparations were assessed by eight course faculty members at one U.S. dental school. Analysis of average interexaminer agreement on these components revealed that six were below 60%. These were proximal contact clearance, retention groove placement, retention groove depth, preparation walls, preparation margins, and preparation toilet/debris. A 30-minute calibration session was subsequently developed to provide discrimination exercises utilizing 3-D models and digital images of various levels of student performance for five of the six components. Immediately following calibration, the course faculty assessed the same 32 preparations (Phase I) followed by a delayed assessment without calibration (Phase II) approximately six months later. The results showed that overall interexaminer reliability improved after calibration. Although there was a decline in interexaminer reliability after an interval of six months (Phase II), the degree of variation among examiners was lower than in the preliminary assessment. These findings support the use of discrimination exercises for preclinical operative dentistry course faculty to increase interexaminer agreement and thereby improve the consistency of faculty-student communication.

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OBJECTIVE: To evaluate the 6-year clinical performance of Xeno IV, Xeno III, and XP Bond adhesives in the restoration of non-carious cervical lesions (NCCLs). METHODS: This was a randomized controlled clinical trial where 39 participants met the inclusion/exclusion criteria and were enrolled. Lesions restored were notch-shaped NCCLs. Prior to adhesive procedures, NCCLs were roughened. No enamel bevel was placed and no mechanical retention was created. Adhesive systems were applied following manufacturer's instructions and the NCCLs were restored with composite resin (TPH(3)). Restorations were finished immediately after placement and scored with regard to retention, marginal discoloration, marginal adaptation, sensitivity, and secondary caries using modified USPHS criteria. Descriptive statistics were performed. Logistic regression models were performed for each outcome separately with compound symmetry correlation structure where teeth were clustered by participants. All analyses were conducted using SAS 9.2. RESULTS: The 6-year recall rate was 77.5% of the restorations (76.9% of the participants). No statistical differences were found between adhesives for retention, marginal discoloration, and marginal adaptation. Restorations failed by loss of retention (16.7%, 27.6%, and 11.8% of Xeno IV, Xeno III, and XP Bond restorations, respectively) and marginal discoloration (7.4% of Xeno IV restorations). For every unit increase in restoration volume it was 1.31 (95%C.I. 1.05, 1.63, P=0.01) times more likely that the restoration retention would be maintained. SIGNIFICANCE: The tested adhesive systems presented similar clinical performance after six years of service, with annual failure rates of 2.8%, 4.6%, and 2.0% for Xeno IV, Xeno III, and XP Bond, respectively.

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Dentiform teeth with simulated caries (DTSC), frequently used in preclinical courses, should show no variability in the amount of simulated caries from tooth to tooth. However, the level of caries variability among DTSC is currently unknown. The aim of this study was to assess the variation in simulated caries levels in one group of DTSC and determine whether variation among DTSC impacted the preclinical performance of dental students. In the study, 80 commercially available mandibular first molar DTSC with simulated mesio-occluso-distal caries were sectioned in coronal (n=40) and sagittal (n=40) planes where the caries depth/width was greatest. Section images were analyzed for variation in levels of simulated caries using image-processing software. Three years of practical performance data using DTSC were compared with three years of practical performance data using dentiform teeth without simulated caries, for a total of six years (students' performance on two exams, Practical 1 and Practical 2). The results showed that 70% of the coronally sectioned teeth had manufacturing defects that resulted in caries overextension at the dentino-enamel junctions (DEJs). Overextensions were found at the DEJ in 41.3% of the sagittally sectioned teeth. There was a statistically significant decrease in Practical 1 performance of the students who used DTSC as compared with students who used teeth without simulated caries (p=0.0001); there was no statistically significant difference on Practical 2 performance. Of the DTSC evaluated in this study, 56.6% contained manufacturing defects, and more than 80% were found to have excessive caries variation. Prediction of which DTSC will have caries overextension is not possible. Students preparing DTSC that contain caries overextension are therefore at increased risk of receiving undeserved negative summative assessment on practical examinations.

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Application of biomodification techniques to dentin can improve its biochemical and biomechanical properties. Several collagen cross-linking agents have been reported to strengthen the mechanical properties of dentin. However, the characteristics of collagen that has undergone agent-induced biomodification are not well understood. The objective of this study was to analyze the effects of a natural cross-linking agent, genipin (GE), on dentin discoloration, collagen stability, and changes in amino acid composition and lysyl oxidase mediated natural collagen cross-links. Dentin collagen obtained from extracted bovine teeth was treated with three different concentrations of GE (0.01%, 0.1%, and 0.5%) for several treatment times (0-24 h). Changes in biochemical properties of NaB(3)H4-reduced collagen were characterized by amino acid and cross-link analyses. The treatment of dentin collagen with GE resulted in a concentration- and time-dependent pigmentation and stability against bacterial collagenase. The lysyl oxidase-mediated trivalent mature cross-link, pyridinoline, showed no difference among all groups while the major divalent immature cross-link, dehydro-dihydroxylysinonorleucine/its ketoamine in collagen treated with 0.5% GE for 24 h, significantly decreased compared to control (P < 0.05). The newly formed GE-induced cross-links most likely involve lysine and hydroxylysine residues of collagen in a concentration-dependent manner. Some of these cross-links appear to be reducible and stabilized with NaB(3)H4.

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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.

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The aim of this study was to evaluate the water sorption and solubility of different adhesives. Adper Easy Bond, Adper Single Bond Plus, Bond Force, Clearfil SE Bond (bonding resin only), and Xeno IV were the materials evaluated. Ten disks of each adhesive were made in Teflon molds and evaporation of any volatile components was allowed. The disks were weighed daily in an analytical balance until a constant mass was obtained (m1). Disks were then immersed in water for 12 months when their wet weight was recorded (m2). The disks were again weighed daily until a constant mass was obtained and the final weight recorded (m3). Water sorption and solubility (percentages) were calculated using the recorded mass values. Kruskal-Wallis tests were used to compare the average water sorption and solubility among the different adhesives. Mann-Whitney tests with a Bonferroni correction were used to determine the pairwise differences between adhesives in water sorption and solubility. The level of significance was set at 0.05. Water sorption and solubility were significantly different among the groups (p<0.05). Pairwise comparisons showed no significant differences (p>0.05) between Adper Single Bond Plus and Bond Force, or between Clearfil SE Bond and Xeno IV in either water sorption or solubility. Xeno IV did not differ from Adper Easy Bond in water sorption (p>0.05). Water sorption and solubility of all-in-one adhesives increased with time, and the rates of increase were composition-dependent. The results suggest that monomers other than HEMA contribute to water sorption and solubility of adhesive systems from different categories.

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The aim of this study was to evaluate the water sorption and solubility of different adhesives. Adper Easy Bond, Adper Single Bond Plus, Bond Force, Clearfil SE Bond (bonding resin only), and Xeno IV were the materials evaluated. Ten disks of each adhesive were made in Teflon molds and evaporation of any volatile components was allowed. The disks were weighed daily in an analytical balance until a constant mass was obtained (m1). Disks were then immersed in water for 12 months when their wet weight was recorded (m2). The disks were again weighed daily until a constant mass was obtained and the final weight recorded (m3). Water sorption and solubility (percentages) were calculated using the recorded mass values. Kruskal-Wallis tests were used to compare the average water sorption and solubility among the different adhesives. Mann-Whitney tests with a Bonferroni correction were used to determine the pairwise differences between adhesives in water sorption and solubility. The level of significance was set at 0.05. Water sorption and solubility were significantly different among the groups (p<0.05). Pairwise comparisons showed no significant differences (p>0.05) between Adper Single Bond Plus and Bond Force, or between Clearfil SE Bond and Xeno IV in either water sorption or solubility. Xeno IV did not differ from Adper Easy Bond in water sorption (p>0.05). Water sorption and solubility of all-in-one adhesives increased with time, and the rates of increase were composition-dependent. The results suggest that monomers other than HEMA contribute to water sorption and solubility of adhesive systems from different categories.

O objetivo deste estudo foi avaliar a absorção de água e a solubilidade de diferentes sistemas adesivos: Adper Easy Bond, Adper Single Bond Plus, Bond Force, Clearfil SE Bond (apenas a resina adesiva) e Xeno IV. Foram fabricados 10 discos de cada material em moldes de Teflon e foi permitida a evaporação de todos os componentes voláteis. Os discos foram pesados diariamente em balança analítica até atingir massa seca constante (m1). Após esta mensuração, os discos foram imersos em água por 12 meses e seu peso úmido foi anotado (m2). Os discos foram novamente pesados diariamente até obter-se massa constante (m3). As percentagens de absorção de água e solubilidade foram calculadas utilizando os valores de massa registrados. A comparação das médias de absorção de água e solubilidade entre os diversos adesivos foi feita com o teste Kruskal-Wallis. As diferenças de absorção de água e solubilidade entre os pares de adesivos foram determinadas pelo testes Mann-Whitney com correção de Bonferroni. O nível de significância adotado foi de 0,05. Absorção de água e solubilidade apresentaram diferenças estatisticamente significantes entre os grupos (p<0,05). As comparações pareadas dos adesivos não mostraram diferenças significantes (p>0,05) entre Adper Single Bond Plus e Bond Force nem entre Clearfil SE Bond e Xeno IV para absorção de água e solubilidade. Xeno IV apresentou diferença significante do Adper Easy Bond quanto à absorção de água (p>0,05). A absorção de água e solubilidade dos adesivos “all-in-one” aumentaram com o tempo e as taxas de aumento mostraram-se dependentes da composição do material. Os resultados sugerem que outros monômeros além do HEMA contribuem para a absorção de água e solubilidade dos diversos sistemas de adesivos.

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STATEMENT OF THE PROBLEM: The long-term patient satisfaction and safety of nightguard vital bleaching (NGVB) requires further evaluation. PURPOSE OF THE STUDY: The purpose of this study was to evaluate patients' satisfaction and identify side effects of NGVB up to 17 years post-treatment. MATERIALS AND METHODS: Thirty-one participants who had completed previous NGVB studies using 10% carbamide peroxide were contacted at least 10 years post-treatment (range 10-17 years, average 12.3 years). Participants reported shade satisfaction (very satisfied [VS], partially satisfied [PS], or not satisfied [NS]) as well as potential complications. Participants had teeth # 6 to 11 examined for tooth vitality, gingival inflammation (Löe's Gingival Index [GI]), and radiographically for external cervical resorption (ECR). RESULTS: All of the participants had successful lightening of their teeth. Sixty-one percent (19) had not retreated their teeth. Of those who had not retreated their teeth and who responded to the question of whitening satisfaction, 31% (4/13) were VS, 54% (7/13) were PS, and 15% (2/13) were NS with their current shade. Of those who had retreated their teeth, all were VS or PS. Ninety-one percent of the examined teeth had GI = 0 (normal), 7% had GI = 1 (mild inflammation), and 2% had GI = 2 (moderate inflammation). Sixty-nine percent of teeth tested responded to a cold stimulus. Radiographs did not detect ECR or apical lesions. No participant reported having a gingival biopsy post-treatment, and 87% would whiten again. CONCLUSIONS: Patient satisfaction with NGVB may last as long as 12.3 years in average (range 10-17 years) post-treatment. GI and ECR findings were considered within the normal expectations for the sample studied, suggesting minimal clinical post-NGVB side effects up to 17 years. CLINICAL SIGNIFICANCE: Nightguard vital bleaching provides patient satisfaction with minimal side effects up to 17 years post-treatment.

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UNLABELLED: statement of problem: Self-etch adhesives typically are mildly acidic and therefore less effective than etch-and-rinse adhesives for bonding to enamel. PURPOSE: The purpose of this study was to evaluate the enamel and dentin shear bond strengths of a new two-step self-etch adhesive system, OptiBond XTR (Kerr Corporation, Orange, CA, USA). MATERIALS AND METHODS: The labial surfaces of 80 bovine teeth were ground to create flat, 600-grit enamel or dentin surfaces. Composite was bonded to enamel or dentin using the new two-step self-etch system or a three-step etch-and-rinse (OptiBond FL, Kerr), two-step self-etch (Clearfil SE Bond, Kuraray America, Houston, TX, USA), or one-step self-etch adhesive (Xeno IV, Dentsply Caulk, Milford, DE, USA). Following storage in water for 24 hours, shear bond strengths were determined using a universal testing machine. The enamel and dentin data sets were subjected to separate analysis of variance and Tukey's tests. Scanning electron microscopy was used to evaluate the effects of each system on enamel. RESULTS: Mean shear bond strengths to enamel ranged from 18.1 MPa for Xeno IV to 41.0 MPa for OptiBond FL. On dentin, the means ranged from 33.3 MPa for OptiBond FL to 47.1 MPa for Clearfil SE Bond. OptiBond XTR performed as well as Clearfil SE Bond on dentin and as well as OptiBond FL on enamel. Field emission scanning electron microscope revealed that OptiBond XTR produced an enamel etch pattern that was less defined than that of OptiBond FL (37.5% phosphoric acid) but more defined than that of Clearfil SE Bond or Xeno IV. CONCLUSION: The new two-step self-etch adhesive system formed excellent bonds to enamel and dentin in vitro. CLINICAL SIGNIFICANCE: OptiBond XTR, a new two-step self-etch adhesive system, is a promising material for bonding to enamel as well as to dentin.

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The presence of matrix metalloproteinase-2 (MMP-2) in dentin has been reported, but its distribution and activity level in mature human coronal dentin are not well understood. The purpose of this study was to determine the MMP-2 distribution and relative activity in demineralized dentin. Crowns of twenty eight human molars were sectioned into inner (ID), middle (MD), and outer dentin (OD) regions and demineralized. MMP-2 was extracted with 0.33 mol x L(-1) EDTA/2 mol xL(-1) guanidine-HCl, pH 7.4, and MMP-2 concentration was estimated with enzyme-linked immunoabsorbant assay (ELISA). Further characterization was accomplished by Western blotting analysis and gelatin zymography. The mean concentrations of MMP-2 per mg dentin protein in the dentin regions were significantly different (P = 0.043): 0.9 ng (ID), 0.4 ng (MD), and 2.2 ng (OD), respectively. The pattern of MMP-2 concentration was OD > ID > MD. Western blotting analysis detected -.66 and -72 kDa immunopositive proteins corresponding to pro- and mature MMP-2, respectively, in the ID and MD, and a -66 kDa protein in the OD. Gelatinolytic activity consistent with MMP-2 was detected in all regions. Interestingly, the pattern of levels of Western blot immunodetection and gelatinolytic activity was MD > ID > OD. The concentration of MMP-2 in human coronal dentin was highest in the region of dentin that contains the dentinoenamel junction and least in the middle region of dentin. However, levels of Western blot immunodetection and gelatinolytic activity did not correlate with the estimated regional concentrations of MMP-2, potentially indicating region specific protein interactions.

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This investigation assessed whether early student performance with a dental handpiece on a didactic training aid known as the Learn-A-Prep II (LAP II) was predictive of performance on subsequent practical examinations in a preclinical restorative dentistry course. Eighty-one first-year students were given initial handpiece training and formative feedback using the LAP II and were then instructed to independently prepare four LAP II patterns within the pattern lines and at a specified depth. Performance on the LAP II was compared with the summative assessment on two subsequent amalgam preparation practical examinations given at the middle (Class II) and end (Complex) of the course. Pattern preparation within the lines did not significantly improve the likelihood of receiving an A or B on the Class II practical (p=0.53) or on the Complex practical (p=0.37). Students who had an acceptable depth on the LAP II were 3.73 times more likely to receive an A or B on the Class II practical than those students who did not have acceptable depth (p=0.03). Performance at an acceptable depth did not significantly improve the likelihood of receiving an A or B on the Complex practical (p=0.15). The LAP II may aid in identification of students who would benefit from early intervention with additional focused instruction.

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Contemporary resin-dentin bonding is initiated by systems that use phosphoric acid or acidic resin monomers to remove mineral, exposing the superficial dentin collagen matrix. Collagen-associated proteins, including enzymes known as matrix metalloproteinases (MMPs), also are exposed. The collagen matrix is subsequently infiltrated with resins that are polymerized to establish an adhesive attachment to the dentin. Exposed collagen matrix that is not infiltrated with the adhesive can be degraded by associated MMPs, which might result in deterioration of the adhesive-dentin bond over time. Chlorhexidine (CHX) is able to inhibit MMPs by binding calcium and zinc ions necessary for proteolytic activity. This Critical Appraisal presents salient publications on research that evaluate CHX and its ability to limit MMP degradation of dentin bonds created by etch-and-rinse and self-etch adhesive systems.

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PURPOSE: To evaluate the shear bond strength (SBS) of a novel low-shrink posterior resin composite (Filtek LS) to various substrates. METHODS: The dedicated LS System Adhesive was used to bond Filtek LS to bovine dentin, ground bovine enamel, resin-modified glass-ionomer liner (Vitrebond Plus), conventional glass-ionomer restorative material (Fuji IX GP Extra), and bovine dentin previously exposed to zinc oxide-eugenol (IRM) (n=10 for each group). Vitrebond Plus and Fuji IX GP Extra substrates were fabricated by filling standardized preparations that had been made in epoxy resin. Adper Scotchbond SE/Filtek Z250 was used as a control. Composites were applied using the Ultradent specimen former. The bonded specimens were stored in water at 37 degrees C for 24 hours, and SBS testing was done using an Instron universal testing machine. The data were analyzed using ANOVA and Tukey-Kramer HSD test at a significance level of 0.05. RESULTS: The mean SBS values of the Filtek LS system were generally somewhat lower than the values of Adper Scotchbond SE/Filtek Z250 to the various substrates, but the differences were not statistically significant. Exposure of dentin to IRM resulted in a statistically significant reduction in the mean SBS values of Adper Scotchbond SE/Z250 and a slight but statistically insignificant reduction for the Filtek LS system.

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