A simple screening tool for occupational burnout among dentists.

BACKGROUND: Nearly 40% of US physicians experience occupational burnout. The actual prevalence rate of burnout among US dentists remains unknown. The authors examined a simplified 2-item burnout screening tool based on the Maslach Burnout Inventory (MBI) to identify possible occupational burnout among dentists. METHODS: Data were obtained from a survey of pediatric dentists (n = 540) in the United States. The full MBI items from the data set were used to determine and categorize emotional exhaustion and depersonalization. Responses to 2 MBI items, 1 for emotional exhaustion and 1 for depersonalization, were analyzed separately and risk of experiencing high MBI emotional exhaustion and depersonalization was calculated using all subscale items for these 2 burnout dimensions. Spearman correlations were used to compare responses to the 2 MBI items and MBI emotional exhaustion and depersonalization. RESULTS: Based on frequency of at least once per week, 18% of respondents had positive response to MBI item "I feel burned out from my work" and had high MBI emotional exhaustion, and 9% had positive response to MBI item "I have become more callous toward people since I took this job" along with high MBI depersonalization. The risk of experiencing the burnout dimensions of high emotional exhaustion and depersonalization increased with positive frequency score for the respective MBI items. There were strong positive correlations between responses to the 2 MBI items and emotional exhaustion and depersonalization scores, respectively. CONCLUSIONS: A simple 2-item burnout screening tool can be used to identify potential occupational burnout among dentists. PRACTICAL IMPLICATIONS: Improving awareness about occupational burnout can help mitigate its detrimental consequences.

Occupational burnout and depression among paediatric dentists in the United States.

BACKGROUND: Paediatric dentists in the United States may be at greater risk for occupational burnout and/or depression because of chronic stress associated with provision of paediatric dental care and increasing prevalence of females in the workforce. AIMS: To determine the prevalence of occupational burnout and/or depression among US paediatric dentists. DESIGN: A self-administered online anonymous survey was sent to members of the American Academy of Pediatric Dentistry (n = 4735). The questionnaire consisted of seven demographic items, 22 items of Maslach Burnout Inventory (Three subscales: Emotional exhaustion, Depersonalization, and Personal accomplishment), and eight items of Patient Health Questionnaire-8. RESULTS: The survey had a response rate of 11.4% (females = 53%). Twenty-three per cent of respondents had high emotional exhaustion while fewer respondents had high depersonalization (12%) or low personal accomplishment (10%). Nine per cent fulfilled the study's definition of occupational burnout (high emotional exhaustion + high depersonalization). Seven per cent of respondents had moderate-to-severe depression and showed significant correlations (P < .05) with high emotional exhaustion, high depersonalization and low personal accomplishment. Two out of five respondents with occupational burnout also had moderate-to-severe depression. There were no gender differences in prevalence of burnout or depression. CONCLUSIONS: Few paediatric dentists had occupational burnout and/or depression.

Proximal contact tightness of class â ¡ bulk-fill composite resin restorations: An in vitro study.

This study investigated the effect of bulk-fill composites on proximal contact tightness (PCT) of composite restorations using different matrix systems. 150/standardized-MO-ivorine cavity preparations were divided into 5 groups; Smart Dentin Replacement (SDR), SonicFill (SF), Tetric EvoCeram Bulk-Fill (TEB), G-ænial Universal Flo (GF) and Tetric EvoCeram (TE). Each group was subdivided into 3 sub-groups (n=10); Dixieland band in Tofflemire retainer, FenderMate and Palodent plus matrix systems. PCT was measured 24 h post-curing using Tooth Pressure Meter. PCT means were calculated and statistically-analyzed using ANOVA and Tukey's post-hoc test (p<0.05). Means and SD of PCT for Tofflemire subgroup were: 1.75(0.13), 3.21(0.1), 3.06(0.19), 2.49(0.21) and 3.18(0.1) for (SDR), (SF), (TEB), (GF) and (TE), respectively. Using FenderMate, values were: 1.87(0.08), 3.35(0.12), 3.17(0.16), 2.64(0.1) and 3.26(0.11) for (SDR), (SF), (TEB), (GF) and (TE), respectively, while with Palodentplus; 3.16(0.17), 4.23(0.11), 4.1(0.1), 3.46(0.17) and 3.98(0.1) for (SDR), (SF), (TEB), (GF) and (TE), respectively. ANOVA revealed significant differences (p<0.05) between all samples except between (SF), (TEB) and (TE) and also significant difference between Palodentplus and two subgroups. Effect of bulk-fill composites on PCT is material dependent. Separation ring is recommended for proper PCT.

Bond Strength of Universal Self-Etch 1-Step Adhesive Systems for Orthodontic Brackets.

OBJECTIVE: The objective of this study was to assess the shear bond strength (SBS) of orthodontic brackets bonded to uncut enamel with universal self-etch 1-step adhesive systems. METHODS: Extracted uncut premolars (n = 160) were randomly divided into 4 groups for treatment with Scotchbond Universal Adhesive (SU), All-Bond Universal (BU), Clearfil Universal Bond (CU) or the control, Adper Scotchbond Multi-Purpose Adhesive. Following bonding of brackets on tooth surfaces, teeth were stored in distilled water for 24 h and 6 months, and brackets were tested for SBS. The adhesive remnant index (ARI) and quantitative percentage of remaining resin (%RR) were recorded. Scanning electron microscopy was used to analyze debonded surfaces qualitatively. SBS and %RR data were analyzed by 2-way ANOVA followed by the Tukey test (α = 0.05). RESULTS: At neither time did these universal adhesives achieve satisfactory SBS for orthodontic treatment. The control group had the highest SBS, ARI score and mean %RR (and these differences were significant), while the BU group had the lowest SBS. SBS mean values and ARI scores decreased over time for SU and BU, but remained stable for CU. There was no difference in %RR among the universal adhesives tested. CONCLUSION: None of the universal adhesives used in self-etch mode achieved SBS values (at 24 h and 6 months) that were satisfactory for orthodontic treatment.

Effect of Training Method on Dental Students' Light-Curing Performance.

The aims of this study were to evaluate 1) the effect of different light-curing training methods on first-year dental students' light-curing performance immediately after and one year after training and 2) the effect of dental student year (first vs. third year) and different light-curing training methods on students' light-curing efficacy. The study was organized into two parts, conducted in 2013 and 2014. In the first part, all students (N=66) in the first-year restorative course at a Canadian dental school were invited to participate in a light-curing activity immediately after training; after 12 months, those students (now in their second year) were asked to again perform the light-curing activity. In the second part, all the subsequent first-year students (N=75) and third-year students (N=95) were invited to perform the same light-curing activity after training. Each class was divided into three groups: the Control group received a lecture; the Tips group received the same lecture plus tips on "7 Steps to Ensure Better Light Curing"; and the Simulator group received the lecture, tips, and hands-on training using the patient simulator. In the first part of the study, all 66 students participated in the first year; 39 of those participated a year later. In the second part, all students in both years participated. For the first part, time had a significant effect on light-curing performance, with significantly higher results in the second year. When the first-year students' results were isolated, training method had a significant effect on mean and maximum irradiance values. The second part found a significant effect of training on mean (p=0.003) and maximum (p=0.021) irradiance. The interaction DDS*training was significant (p=0.037) when the after-training values were analyzed. These results point to the need for further research to determine the most effective light-curing training methods.

Gingival microleakage of class II bulk-fill composite resin restorations.

BACKGROUND: Bulk-fill composites were developed to simplify composite placement and minimize polymerization shrinkage stresses, which can improve gingival marginal adaptation in deep class II cavities. OBJECTIVES: The objective of this study was to compare the gingival microleakage of class II cavities restored with bulk-fill composites to that of incrementally restored ones with a conventional composite at 2 storage periods. MATERIAL AND METHODS: Forty freshly extracted intact molars were employed. Two standardized class II slot cavities, 3-millimeter-wide buccolingually, with the gingival floor 0.5 mm below the cementoenamel junction (CEJ) and the axial wall depth of 1.3 mm were prepared in each tooth (80 cavity preparations). The prepared teeth were divided equally into 3 bulk-fill groups (Tetric EvoCeram® Bulk Fill, X-tra Fil® and QuiXX®) and 1 control group (TPH Spectra® HV). Each group was subdivided into 2 equal subgroups (n = 10) according to the storage period in distilled water (24 h and 6 months). The Adper® Single Bond Plus adhesive was used with all the restorative materials. The cavities in the experimental groups were restored with 4-millimeter bulk-fill composites in 1 increment, while the cavities in the control group were restored with 2 increments of the thickness of 2 mm. The polymerization light was applied from the occlusal surfaces. The teeth were then immersed in 2% procion red dye solution, sectioned and examined under a stereomicroscope to determine the extent of dye penetration. The data was statistically analyzed using the Kruskal-Wallis test and the Mann-Whitney U test. RESULTS: The Kruskal-Wallis test revealed no significant differences in the mean microleakage scores among all the groups after 24-hour and 6-month storage (p = 0.945 and p = 0.928, respectively). The Mann-Whitney U test revealed an increase in the mean microleakage scores in all the groups after 6-month storage; however, the scores were not significantly different from the means obtained after 24 h (p = 0.259 for Tetric EvoCeram Bulk Fill; p = 0.205 for X-tra Fil; p = 0.166 for QuiXX; p = 0.155 for TPH Spectra HV). CONCLUSIONS: Gingival microleakage of bulk-fill composites in class II cavities was not significantly different from that of incrementally restored ones with a conventional composite. The increase in the mean gingival microleakage of the specimens stored for 6 months was not statistically significantly different in comparison to the values obtained after the 24-hour storage period for each composite.

Cuspal Deflection of Premolars Restored with Bulk-Fill Composite Resins.

OBJECTIVE: This in vitro study compared cuspal deflection of premolars restored with three bulk-fill composite resins to that of incrementally-restored ones with a low-shrinkage silorane-based restorative material. MATERIALS AND METHODS: Forty freshly-extracted intact human upper premolars were used. Reference points at buccal and palatal cusp tips were acid-etched and composite rods were horizontally bonded to them (TPH-Spectra-HV, Dentsply). Two acrylic resin guiding paths were made for each premolar to guide beaks of a digital micrometer used for cuspal deflection measurements. Standardized MOD cavities, 3 mm wide bucco-lingually and 3.5 mm deep, were prepared on each premolar. Prepared teeth were then equally divided into four groups (n = 10) and each group was assigned to one of four composite resin (QuiXX, Dentsply; X-tra fil, Voco; Tetric EvoCeram Bulk Fill, Ivoclar Vivadent; low-shrinkage Filtek LS, 3M/ESPE). Adper Single Bond-Plus, 3M/ESPE was used with all bulk-fill restoratives. LS-System Adhesive, 3M/ESPE was used with Filtek LS. For each prepared premolar, cuspal deflection was measured in microns as the difference between two readings between reference points before and after restoration completion. Means and SDs were calculated and data statistically-analyzed using One-way ANOVA and Tukey's test. RESULTS: Filtek LS showed the lowest mean cuspal deflection value 6.4(0.84)µm followed by Tetric EvoCeram Bulk Fill 10.1(1.2) µm and X-tra fil 12.4(1.35)µm, while QuiXX showed the highest mean 13(1.05)µm. ANOVA indicated significant difference among mean values of groups (p < 0.001). Tukey's test indicated no significant difference in mean values between QuiXX and X-tra fil (p = 0.637). CONCLUSIONS: Tetric EvoCeram Bulk Fill had significantly lower mean cuspal deflection compared with the two other bulk-fill composite resins tested. Filtek LS had the lowest significant mean cuspal deflection in comparison to all tested bulk-fill restoratives. CLINICAL SIGNIFICANCE: The use of Tetric EvoCeram Bulk fill composite resin restorative for class II MOD cavities resulted in reduced cuspal deflection in comparison to the two other bulk-fill composite resins tested. The silorane-based Filtek LS restorative resulted in the least cuspal deflection in comparison to all tested bulk-fill composite restoratives.

Clinical Performance of Pedo Jacket Crowns in Maxillary Anterior Primary Teeth.

PURPOSES: To assess the clinical performance of Pedo Jacket crowns for restoration of carious primary anterior teeth. METHODS: A total of 129 carious primary incisors and canines of 48 children younger than 71 months of age- were restored with Pedo Jacket crowns and resin-modified glass ionomer cementation. They were assessed for: ease of use; presence of recurrent decay; wear; partial or complete loss of the crown; color stability; gingival health; and overall clinical success over a 12-month follow-up. The patient's behavior at the restorative appointment during crown placement was also assessed. RESULTS: An overall clinical success of 89.5 percent of the teeth in 87.3 percent of the children was seen one year later. The crowns were easy to use, even in uncooperative children. The color stability, wear, plaque accumulation, and gingival health were acceptable. Discoloration, wear, or complete loss of the crown were found in 13.1 percent, 5.4 percent, and 7.6 percent of children, respectively. Although not statistically significant, failures were associated with poor patient cooperation at the time of crown placement, poor oral hygiene, or operator error. CONCLUSION: Pedo Jacket crowns are a viable treatment alternative for carious maxillary primary anterior teeth.

Gingival microleakage of class V composite restorations with fiber inserts.

AIM: This study investigated the effect of different fiber inserts (glass and polyethylene), bonding agents, and resin composites on the gingival margin microleakage of class V composite restorations. MATERIALS AND METHODS: Sixty premolars were sterilized and mounted in acrylic resin bases. Class V cavities were prepared buccally and lingually, 1 mm below the cementoenamel junction, comprising 12 groups (n = 10). In the experimental groups fiber inserts were cut and placed at the gingival seat, while the control groups had no inserts. Combinations of two composite materials, Filtek-Z250 and Filtek-LS (3M-ESPE), and four bonding agents, Clearfil SE bond (Kuraray) (C), Scotch Bond Multipurpose (3M-ESPE) (SB), Prime and Bond NT (Dentsply) (PB), and Filtek-LS (3M-ESPE) (LS) were used. Restorations were incrementally inserted and polymerized for 40s. Specimens were then stored in distilled water for 7 days and thermocycled for 500 cycles. Teeth surfaces were sealed with nail polish except for 1 mm around restoration margins and immersed in 2% red procion dye. Teeth were then sectioned buccolingually and dye penetration was assessed with five-point scale. Data were statistically-analyzed by Kruskal-Wallis, ANOVA and Tukey's tests (α = 5%). RESULTS: Mean microleakage scores varied from 0.40 (Groups C, C with polyethylene, LS, LS with polyethylene) to 1.50 (SB). CONCLUSION: Different bonding agents led to differences in microleakage scores where C and LS showed significantly lower microleakage than PB. SB had highest mean microleakage score, however, incorporation of fibers resulted in significant reduction in microleakage. CLINICAL SIGNIFICANCE: Class V resin composite restorations bonded with a total-etch adhesive had a significant reduction in mean microleakage scores when glass or polyethylene fibers were placed at the gingival cavo-surface margin. In contrast, for two self-etch adhesive systems, the incorporation of fibers had no significant effect on mean microleakage scores.

Effect of composite insertion technique on cuspal deflection using an in vitro simulation model.

OBJECTIVE: The objective of this study was to investigate, by simulation, the effect of conventional composite resin insertion techniques on cuspal deflection using bonded typodont artificial teeth. The deflection produced by a new low-shrinkage composite was also determined. MATERIALS AND METHODS: Sixty standardized MOD preparations on ivorine maxillary premolars were prepared: group A at 4 mm depth and group B at 6 mm depth. Each group was further subdivided according to composite insertion technique (n=6), as follows: 1) bulk insertion, 2) horizontal increments, 3) tangential increments, and 4) a modified tangential technique. Preparations were microetched, acid-cleaned, and bonded with adhesive resin to provide micromechanical attachment before restoration with a conventional composite (Spectrum TPH( 3 ), Dentsply). Two additional subgroups at 4 mm and 6 mm depth (n=6) were restored in bulk using low-shrinkage composite (Filtek LS, 3M/ESPE). All groups received the same total photo-polymerization time. Cuspal deflection was measured during the restorative procedure using two Linear Variable Differential Transformers attached to a data acquisition system. RESULTS: The average cuspal deflections for group A were 1) 40.17 ± 1.18 µm, 2) 25.80 ± 4.98 µm, 3) 28.27 ± 5.12 µm, and 4) 27.33 ± 2.42 µm. The deflections in group B were 1) 38.82 ± 3.64 µm, 2) 50.39 ± 9.17 µm, 3) 55.62 ± 8.16 µm, and 4) 49.61 ± 8.01 µm. Cuspal flexure for the low-shrinkage composite was 11.14 ± 1.67 µm (group A: 4 mm depth) and 16.53 ± 2.79 µm (group B: 6 mm depth). CONCLUSIONS: All insertion techniques using conventional composite caused cuspal deformation. In general, deeper preparations showed increased cuspal deflection-except in the case of bulk insertion, which was likely affected by decreased depth of cure. Cuspal movement using low-shrinkage composite was significantly reduced.

Microshear bond strength of self-etching adhesives to caries-affected dentin identified using the dye permeability test.

PURPOSE: The aim of this study was to compare microshear bond strength (µSBS) of different adhesives to normal dentin (ND) and caries-affected dentin (AD) as differentiated using the dye permeability test. MATERIALS AND METHODS: One hundred freshly extracted carious teeth were ground to expose normal and cariesaffected dentin. Differentiation between both substrates was carried out using microhardness and a new dye permeability method. Ground teeth were divided into 5 groups according to the adhesive tested; Clearfil SE Bond (SE), Clearfil DC Bond (DC) (Kuraray), Bond Force (BF) (Tokuyama), AdheseOne (AH) (Ivoclar), Adper Prompt-L-pop (PR) (3M ESPE). Adhesives were applied to selected substrate, and composite cylinders (0.9 mm diameter x 0.7 mm length) were formed. After 24 h, specimens were subjected to microshear testing at a crosshead speed of 0.5 mm/min. Failure modes were determined using a stereomicroscope at 40X magnification. Data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests. RESULTS: Normal dentin was permeable for the dye, while caries-affected dentin was impermeable. Vickers hardness numbers (VHN) for normal and caries-affected dentin were 63.98 ± 3.24 and 62.40 ± 3.49 respectively, which were not significantly different (p > 0.05). µSBS values were: SE-ND = 22.34 ± 6.4, SE-AD = 18.70 ± 4.0, BF-ND = 24.52 ± 4.9, BF-AD = 18.31 ± 4.9, DC-ND = 24.49 ± 8.0, DC-AD = 18.97 ± 9.4, AH-ND = 17.21 ± 6.8, AH-AD = 17.03 ± 10.3, PR-ND = 13.67 ± 4.4, PR-AD = 7.31 ± 2.4 MPa. A statistically significant difference was found among the adhesive systems to both normal (p < 0.01) and caries-affected dentin (p < 0.001). However, µSBS of SE, DC, and AH adhesives to normal dentin were not significantly different from those of caries-affected dentin (p > 0.05). CONCLUSIONS: The permeability test was an effective tool to differentiate between normal and caries-affected dentin. Some adhesive systems showed no significant difference in their bond to normal or affected dentin.

Microshear bond strength and interfacial morphology of etch-and-rinse and self-etch adhesive systems to superficial and deep dentin.

OBJECTIVE: To compare microshear bond strength (uSBS) of two pairs of etch-and-rinse and self-etch adhesives to superficial and deep dentin. METHOD AND MATERIALS: Occlusal surfaces of 40 sound extracted noncarious human molars were ground to obtain flat dentin surfaces (20 superficial and 20 deep dentin). Twenty-four teeth were used for uSBS test and 16 for scanning electron microscopic examination. Each dentin group was randomly assigned into four groups, according to the adhesive system tested. An etch-and-rinse and a self-etch adhesive from the same manufacturer were utilized: Scotchbond-MultiPurpose and Adper-Scotchbond SE and XP Bond and Xeno IV. CeramX was used for composite microcylinder construction (0.9 mm in diameter and 0.7 mm in height). Five composite microcylinders were constructed on each dentin surface (n = 15 per group). A Lloyd universal testing machine was used to test uSBS at a crosshead speed of 0.5 mm/min. Fractographic analysis of the failure site was performed using a stereomicroscope and measured by image-analysis software. Data were statistically analyzed using ANOVA and Duncan tests. RESULTS: In superficial dentin, Xeno IV showed significantly the highest uSBS, while in deep dentin, XP Bond showed the highest uSBS. The lowest uSBS values in both dentin depths were recorded for Adper-Scotchbond SE. Etch-and-rinse systems bonded better to deep than to superficial dentin, while self-etching systems showed similar performance at both dentin depths. CONCLUSION: Bond strength to dentin is both adhesive- and substrate-dependent. Contemporary adhesive systems may produce variable bonding results to superficial and deep dentin due to variations in their composition rather than their bonding approach or application technique.

Nanoleakage for Self-Adhesive Resin Cements used in Bonding CAD/CAD Ceramic Material to Dentin.

OBJECTIVES: To determine nanoleakage of CAD/CAM ceramic blocks bonded to dentin with self-adhesive resin cement. METHODS: Eighteen sound extracted human molars were sterilized and sectioned into 3 mm-thick dentin sections. Trilux Cerec Vitablocks (Vita) were also sectioned into 3 mm sections, surface-treated using 5% hydrofluoric acid-etchant, and then coated with silane primer (Vita). Trilux and dentin sections were cemented together by means of three resin cements: Rely-X Unicem (3M/ESPE), BisCem (Bisco), and Calibra (Dentsply), according to manufacturers' recommendations. Calibra was used in conjunction with Prime/Bond-NT adhesive (Dentsply), while the other two are self-adhesive. The bonded specimens were stored for 24h in distilled water at 37°C. Specimens were vertically sectioned into 1 mm-thick slabs, yielding up to six per specimen. Two central slabs were randomly chosen from each specimen making up the cement groups (n=12). Each group was subdivided into two subgroups (n=6), a control and a thermocycled subgroup (5-55°C) for 500 cycles. Slabs were coated with nail polish up to 1 mm from the interface, immersed in a 50% silver nitrate solution for 24h, and tested for nanoleakage using Quanta Environmental SEM and EDAX. Data were statistically analyzed using two-way ANOVA and Tukey's post-hoc tests. RESULTS: Rely-X Unicem and Calibra groups demonstrated no significant difference in the percentage of silver penetration, while the BisCem group revealed a significantly higher percentage (P≤.05). Thermocycling (500 cycles) did not have a statistically significant effect on the percentage of silver penetration (P>.05). CONCLUSIONS: One self-adhesive-resin cement demonstrated a similar sealing ability when compared with a standard resin cement. Thermo-cycling did not significantly increase dye penetration under the test conditions.

Effect of pretest storage conditions of extracted teeth on their dentin bond strengths.

STATEMENT OF PROBLEM: It is becoming increasingly difficult to obtain sufficient freshly extracted human teeth to utilize in in vitro studies, particularly for bonding investigations. PURPOSE: The purpose of this study was to investigate the effect of different storage conditions for human extracted teeth prior to their use in microtensile bond strength (microTBS) testing. MATERIAL AND METHODS: Thirty incisors were divided into groups according to their storage time and condition. The first group consisted of freshly extracted teeth. Teeth of the second group were stored in chloramine-T at 4 degrees C for 2 years +/-1 month. The last group was stored dry for up to 2 years +/-2 months, after which teeth were rehydrated in distilled water for 2 weeks before use. All teeth were disinfected using 0.5% chloramine-T. Dentin surfaces were exposed and then bonded using Scotchbond Multi-Purpose or Clearfil SE Bond to composite resin foundations (Esthet-X). Following 24-hour storage, bonded teeth (n=30) were sectioned into beams with a cross-section of 0.9 +/-0.1 mm(2) and subjected to microTBS testing using a microtensile testing machine (Micro Tensile Tester). Data were calculated and statistically analyzed using Kruskal-Wallis and Mann-Whitney tests (alpha=.05). Failure modes were determined using a stereomicroscope at x40 magnification. RESULTS: Statistical analysis revealed no significant difference between the different storage conditions nor between the 2 adhesive systems for each storage condition (P>.05). Modes of failure for all tested groups were predominantly adhesive followed by mixed. CONCLUSIONS: Within the limitations of this study, it was concluded that aging of teeth and storage conditions had no significant effect on dentin microtensile bond strength to composite resin.

Effect of in-office bleaching on color and surface roughness of composite restoratives.

OBJECTIVES: The purpose of this study was to determine color changes and surface roughness of composites when they were subjected to in-office bleaching. METHODS: 12 discs 15 mm in diameter and 2 mm thick were prepared from two shades (A2 & A4) of two composites, Durafil VS (DF) and TPH3 (TPH). Specimens were polished and stored in distilled water for 24 hours at 37 degrees C before being subjected to bleaching, staining, and re-bleaching. Each of the groups of specimens (DF-A2, DF-A4, TPH-A2 and TPH-A4) were subdivided into three subgroups (n=4) and bleached with Beyond, LumaWhite-Plus, and Opalescence-Boost. Specimens were then stained by immersing them in a coffee solution for 48 hours at 37 degrees C, and then they were re-bleached. Colorimetric measurements were performed at baseline, after bleaching, after staining, and after re-bleaching. Surface roughness was determined with environmental SEM before and after bleaching. Data were statistically-analyzed. RESULTS: None of the bleaching systems notably changed the color of composites (delta-E<2). Coffee staining affected DF specimens more than TPH. Stained specimens showed variable responses to whitening with no significant color change observed with TPH (delta-E<2) and significant changes observed with DF. Surface roughness significantly changed with bleaching, but the degree varied according to composite shade and bleaching agent. CONCLUSIONS: Three in-office bleaching agents had no significant color changes on two composites. DF showed more color change than TPH when immersed in coffee. Stained composites showed different degrees of whitening, with DF showing more response. Bleaching may adversely affect the surface texture of composites. Dentists should take into consideration that composite restorations may not respond to bleaching in the same way that natural teeth do.

Evaluation of proximal contact tightness of Class II resin composite restorations.

OBJECTIVE: The objective of the current study was to compare in-vitro the proximal contact tightness (PCT) of Class II resin composite restorations (RCR) placed with different established and new placement techniques. METHODS: 105 ivorine lower left first molars with standardized MO cavities were randomly divided into seven groups (n = 15) as follows: SRing: sectional matrix and separation ring (Garrison Dental); CRing: circumferential matrix (1101-c, KerrHawe SA) with separation ring; CWedge: circumferential matrix with a wedge only; COptra: circumferential matrix and OptraContact (Vivadent); CCerana: circumferential matrix and a Cerana insert (Nordiska Dental); CElliot: circumferential matrix and Elliot separator (PFINGST & Co) and Walser: Walser matrix O-type (Dr Walser Dental GmbH). In all the groups, the matrix band was secured using a wooden wedge except for the Walser group, following manufacturer's recommendations. A Tofflemire retainer (Kerr Corporation) was used to apply the circumferential matrix band whenever it was used. All the prepared teeth were restored with resin composite (Premise, Kerr) mounted in a manikin head to simulate the clinical environment. PCT was measured using the Tooth Pressure Meter (University of Technology, Delft). The data were analyzed using one-way ANOVA and Tukey post-hoc tests (p < 0.05). RESULTS: Compared to the control group (SRing) (6.64 +/- 1.06N), all other systems resulted in significantly lower PCT values (p < 0.001). Within the circumferential matrix groups, CRing (4.01 +/- 0.53N) and CElliot (4.29 +/- 1.08N) showed significantly tighter contacts compared to the CWedge (0.37 +/- 0.22N), COptra (0.91 +/- 0.49N), CCerana (2.99 +/- 1.98N) and Walser (1.34 +/- 0.55N) (p < 0.05) group. Between CWedge and COptra, no significant difference was found (p = 0.57). CONCLUSION: The use of separation rings with sectional matrices provides superior contacts when placing Class II RCRs.

Effect of the number of applications of acetone-based adhesives on microtensile bond strength and the hybrid layer.

PURPOSE: The current study was carried out to evaluate the effect of doubling the adhesive layers of three acetone-based adhesives on the microtensile bond strength and ultra morphological characterization of the resin dentin interface using SEM. MATERIALS AND METHODS: A total of 27 caries-free human molars were used. Superficial flat dentin surfaces were obtained by wet grinding the buccal surfaces. Three adhesive systems Prime & Bond NT (G1), XENO IV (GII) and G BOND (GIII) were used according to three different protocols: (A) according to the manufacturer's instructions, (B) doubling the adhesive layers and light curing and (C): doubling the adhesive layers with intermediate curing between each layer. Resin composite buildups were made using TPH Spectrum resin composite on the bonded surfaces in 1 mm light cured increments for 40 seconds each. The bonded teeth were sectioned to obtain sticks for microtensile testing. The testing was conducted using a universal testing machine at a crosshead speed of 1 mm/minute. The microtensile bond strength means and standard deviations were calculated and the data were statistically analyzed using Two-way Analysis of Variance (ANOVA) and Tukey's post-hoc tests (p < or = 0.05). Ultra morphological characterization of the resin-dentin interface and representative fractured dentin specimens were examined using SEM. RESULTS: When applied according to the manufacturer's instructions, Prime & Bond NT (total etch adhesive) showed significantly high microtensile bond strength with a mean value +/- SD of 35 +/- 12.7 MPa followed by XENO IV (21.2 +/- 9.4 MPa), while G BOND presented a significantly lower mean value (10.9 +/- 2.9 MPa). Doubling the adhesive layers significantly reduced the mean strength of the total etch adhesive system; in contrast, it significantly increased the bond strength of both self-etch adhesives. The relatively thicker adhesive layer was seen with the total-etch adhesive when the application was doubled, while the hybrid layer appeared thicker with self-etch adhesives. CONCLUSIONS: Doubling the adhesive layer applications significantly improved the bond strength of the two self-etch adhesives (XENO IV and G BOND); however, it had a negative effect on the bond strength of the total-etch adhesive (Prime & Bond NT).

Effect of LED light-curing on the relative hardness of tooth-colored restorative materials.

OBJECTIVE: To determine the relative hardness of GI-based restorative materials using both LED and QTH curing lights at different post-irradiation intervals. METHODS: Four restorative materials (Z250, Beautifil, Dyract AP and Fuji II LC) with shade A3.5 were tested in conjunction with three LCUs (Astralis 3, Blue phase and Radii). The specimens were prepared using specially constructed molds, irradiating only the top surface to an equivalent energy density (J/CM). Vickers microhardness measurements were performed for both the top and bottom surfaces of all specimens following dry storage for 15 minutes in the dark. The measurements were repeated after 24 hours and 7 days. Mean VHNs and SD of the top and bottom surfaces of each specimen were calculated. Relative hardness values (RH) were also determined and mean RH was calculated for each group. RESULTS: The top surface of the Z250, Beautifil and Dyract materials were significantly harder than the bottom surface (p < 0.05) with all LCUs and at all time intervals. Conversely, a different trend was observed with Fuji II LC, where bottom surface VHNs were significantly higher than top surface values (p < 0.05). Blue phase was the only LCU that recorded RH values above 80% for all tested material at all post-irradiation intervals. CONCLUSIONS: A high-intensity LED LCU used for 10 seconds resulted in RH values greater than 80%, with all four restoratives tested indicating a sufficient degree of monomer conversion with such a short curing cycle.