In vitro comparison of an Er:YAG laser-activated bleaching system with different light-activated bleaching systems for color change, surface roughness, and enamel bond strength.

To compare an Er:YAG laser-activated bleaching system with different light-activated in-office bleaching systems for color change, surface roughness, and post-bleaching enamel bond strength. 51 enamel slabs were prepared from the sound buccal enamel of extracted bovine teeth. The teeth were randomly divided into three groups according to different light-activated office bleaching systems (n = 17): diode laser (Epic, Biolase) (940 nm, 7 W, continuous mode), Er:YAG laser (LightWalker, Fotona) (2940 nm, 50 mJ, 10 Hz, 1000 µs), and LED (Radii Plus) (440-480 nm, 1500 mW/cm2). All systems were used with their compatible bleaching agents according to manufacturers' recommendations. The tooth color and surface roughness (Ra) were assessed at baseline and after bleaching using a spectrophotometer and a surface profilometer, respectively. The color change was determined by the CIE L*a*b* system (ΔE, ΔL*, Δa*, Δb*). Kruskal-Wallis test was used for color change whereas Kruskal-Wallis and Wilcoxon tests were used to analyze the roughness data. For shear bond strength test (SBS), composite cylinders were bonded on bleached enamel samples 14 days after bleaching procedures and stored in water (37 °C). Specimens were then debonded with a universal testing machine at 1 mm/min and data were analyzed by using Kruskal-Wallis test. All the tested bleaching systems were effective on color change (ΔE > 3.3) and produced similar color change (p > 0.05). There were no significant differences among the Ra values of the groups neither at baseline nor after bleaching (p > 0.05). However, comparing the baseline and after bleaching Ra values, a significant increase was observed for all tested groups (p < 0.05). Significant differences were also found among all systems for SBS (p < 0.05). The highest values were obtained in Er:YAG group, whereas the LED group revealed the lowest values (p < 0.05). All tested bleaching systems were effective on tooth whitening, whereas they all led to an increase on surface roughness. Although the current Er:YAG laser-activated bleaching system did not differ from other tested bleaching systems according to color change and surface roughness, it appears to provide better results in terms of SBS.

Influence of laser etching on enamel and dentin bond strength of Silorane System Adhesive.

The aim of this in vitro study was to evaluate the shear bond strength (SBS) of Silorane System Adhesive to enamel and dentin surfaces that had been etched with different procedures. Ninety freshly extracted human third molars were used for the study. After the teeth were embedded with buccal surfaces facing up, they were randomly divided into two groups. In group I, specimens were polished with a 600-grit silicon carbide (SiC) paper to obtain flat exposed enamel. In group II, the overlying enamel layer was removed and exposed dentin surfaces were polished with a 600-grit SiC paper. Then, the teeth in each group were randomly divided into three subgroups according to etching procedures: etched with erbium, chromium:yttrium-scandium-gallium-garnet laser (a), etched with 35% phosphoric acid (b), and non-etched (c, control). Silorane System Adhesive was used to bond silorane restorative to both enamel and dentin. After 24-h storage in distilled water at room temperature, a SBS test was performed using a universal testing machine at a crosshead speed of 1 mm/min. The data were analyzed using two-way ANOVA and Bonferroni tests (p < 0.05). The highest SBS was found after additional phosphoric acid treatment in dentin groups (p < 0.05). There were no statistically significant differences between the laser-etched and non-etched groups in enamel and dentin (p > 0.05). The SBS of self-etch adhesive to dentin was not statistically different from enamel (p > 0.05). Phosphoric acid treatment seems the most promising surface treatment for increasing the enamel and dentin bond strength of Silorane System Adhesive.

Comparison of the effects of Er,Cr:YSGG laser and different cavity disinfection agents on microleakage of current adhesives.

The aim of this study was to compare the effect of the Er,Cr:YSGG laser and different cavity disinfection agents on microleakage of an etch-and-rinse and a self-etch adhesive. Class V preparations were completed on the buccal and lingual surfaces of 30 extracted noncarious human molars. The occlusal margin was placed on enamel and the gingival margin on dentin. Preparations were randomly divided into five experimental groups (n = 12); (1) 2% chlorhexidine gluconate (CHX), (2) propolis, (3) ozone, (4) Er,Cr:YSGG laser, and (5) control (no treatment). Each group was divided into two subgroups according to the adhesive system: etch-and-rinse (Adper Single Bond 2), and a self-etch adhesive (All-Bond SE). The preparations were bulk-filled with a resin composite (Arabesk). After storage in distilled water for 24 h the restored teeth were subjected to thermocycling (1,000 cycles; 5-55°C). All specimens were immersed in 0.5% basic fuchsin solution for 24 h and sectioned longitudinally through the centre of the restorations and examined under a stereomicroscope at ×25 magnification. The data were analysed using the Kruskal-Wallis and Mann-Whitney U-tests. No difference was observed between the groups either on enamel or dentin when the etch-and-rinse adhesive was used (p > 0.05). In the self-etch adhesive groups, a significant difference was found only between the laser group and the CHX group on enamel and between the propolis group and the control group on dentin (p < 0.05). Comparing the etch-and-rinse and self-etch adhesives within each group, no differences were found on dentin (p > 0.05). On enamel, a statistically significant difference was found only in the CHX group (p < 0.05). There were no differences in microleakage with the laser and the different cavity disinfectant applications when used with etch-and-rinse adhesive. In the self-etch group there were differences in microleakage depending on the disinfection agent used.

Sealing ability of retrofilling materials following various root-end cavity preparation techniques.

The aim of this study is to compare the sealing efficacy of the retrograde cavity preparations prepared and filled with different equipment and materials. In the study, low speed burs, ultrasonic or Er, Cr:YSGG laser devices were used for cavity preparations and ProRoot MTA and MTA-Angelus as filling materials. Seventy-eight single-rooted teeth were instrumented, root filled, and grouped. Root-end cavities were prepared and filled by using the following: Group 1: Low-speed carbide bur + ProRoot MTA; Group 2: Low-speed bur + MTA-Angelus; Group 3: Ultrasonic retrotips + ProRoot MTA; Group 4: Ultrasonic retrotips + MTA-Angelus; Group 5: Er, Cr:YSGG laser tips + ProRoot MTA; Group 6: Er, Cr:YSGG laser tips + MTA-Angelus. Microleakage was measured using a fluid filtration technique. Differences in the fluid movement among groups were analyzed with a two-way analysis of variance (ANOVA) and LSD test. The results showed a significant difference between the groups prepared with laser and carbide bur (p < 0.05). No difference was found between root-end filling materials (p > 0.05). According to the results of the study, the cavities prepared with Er, Cr:YSGG laser demonstrated significantly lower microleakage in all the filling materials considered.

Effects of different cavity disinfectants on shear bond strength of a silorane-based resin composite.

AIM: This in vitro study evaluated the effect of different cavity disinfection agents on bond strength of a silorane-based resin composite. MATERIALS AND METHODS: Thirty-six caries-free human third mandibular molars sectioned in mesio-distal direction were mounted in acrylic resin with their flat dentin surfaces exposed. After the dentin surfaces were wet ground with # 600 silicon carbide paper, the teeth were randomly divided into 6 groups of 12 each according to the cavity disinfection agents; chlorhexidine (CHX); sodium hypochlorite (NaOCl), propolis, ozone, Er,Cr:YSGG laser and no treatment (control). After treatment of dentin surfaces with one of these cavity disinfection agents, Filtek Silorane adhesive system was applied. The silorane-based resin composite, Filtek Silorane was condensed into a mold and polymerized. After storage at 37°C for 24 hours, the specimens were tested in shear mode at a crosshead speed of 1.0 mm/minute. The results were analyzed by one-way ANOVA. RESULTS: No statistically significant difference was observed between the groups (p>0.05). CONCLUSION: The use of the tested cavity disinfection agents, chlorhexidine, sodium hypochlorite, propolis, ozone and Er,Cr:YSGG laser did not significantly affect the dentin bond strength of a silorane-based resin composite, filtek supreme. CLINICAL SIGNIFICANCE: Cavity disinfectant applications did not affect the dentin bond strength of a silorane-based resin composite.

Clinical comparison of bur- and laser-prepared minimally invasive occlusal resin composite restorations: two-year follow-up.

This study evaluated the two-year clinical performance of two minimally invasive cavity preparation techniques, bur and laser, in Class I occlusal resin composite restorations. Twenty-seven patients, each having at least one pair of occlusal caries, were enrolled in this study. For each patient, one of the cavities was prepared with a diamond bur, and the other was prepared with Er, Cr:YSGG laser. The cavities were restored with a nanofilled flowable resin composite, Grandio Flow, using an etch-and-rinse adhesive, Solobond M. A total of 108 restorations were placed in molars by a single operator. The restorations were evaluated according to modified Cvar/Ryge criteria. The evaluations were performed at baseline, 6, 12, 18 and 24 months after initial placement by two calibrated operators. The Chi-square and Fisher's exact test were used for statistical analysis. All the patients were available during all evaluated periods, resulting in a recall rate of 100%. The retention rates of the restorations at 24 months were 98.1% for bur and 100% for the laser-prepared group. After 24 months, 5.6% of the bur-prepared and 7.4% of the laser-prepared restorations were rated Bravo in marginal discoloration (p > 0.05). Bur-prepared (9.3%) and laser-prepared (13%) restorations were rated Bravo in marginal adaptation (p > 0.05). There were no significant differences between the two cavity preparation techniques regarding the evaluated parameters (p > 0.05). Both cavity preparation techniques performed equally, with excellent outcomes after a 24-month period.

Compressive shear bond strength of core buildup materials.

New tooth-colored restorative materials have been developed with the goal of replacing amalgam. These restoratives are marketed as packable composite and ormocer. The purpose of the present study was to compare the compressive shear bond strengths of these new materials with that of hybrid composite and amalgam as core materials. Standardized core buildups were made on four groups of extracted molars, with 10 teeth per group. Three tooth-colored restorative materials (Filtek Z 250, Filtek P 60, and Definite) and an amalgam (SDI Permite) were used. Specimens were placed in a special jig at a 45-degree angle. The compressive shear bond strength was obtained using a universal testing machine. The Kruskal-Wallis test was used to compare the groups, and pairwise comparisons were made by Mann-Whitney U test (P < .05). Filtek P 60, a packable composite resin, had the greatest compressive shear bond strength values in all instances, and the ormocer (Definite) had the lowest. The strengths of packable composite, hybrid composite, and amalgam as core materials were not significantly different (P > .05).

Fracture resistance of class II preformed ceramic insert and direct composite resin restorations.

OBJECTIVES: This study aimed to compare the fracture resistance of two different posterior restorations in class II cavities. METHODS: In this study 24 extracted intact human mandibular molars (for testing) and 24 extracted intact human teeth (for achieving contact) were used. The test teeth were divided into two groups and then mounted in normal anatomic relationship with intact human teeth on the same holder. Thus 12 pairs of teeth were constituted in each group. Class II MO cavities were prepared on testing teeth in each holder. The other tooth was used for achieving contact. The cavities in group 1 were restored with direct composite resin with the manufacturer's flowable composite. The cavities in group 2 were restored with SONICSYS inlays (preformed ceramic insert) according to the manufacturer's instructions. The marginal ridges of the restorations were loaded at an angle of 13.5 degrees to the long axis of the tooth in an Instron testing machine until failure occurred. RESULTS: Analysis of mean failure loads indicated that class II SONICSYS inlay restorations (group 2) had a significantly greater fracture resistance than did class II direct composite resin restorations with flowable composite (P=0.000). CONCLUSIONS: The SONICSYS inlay system provided greater fracture resistance than direct composite resin with flowable composite.

Fracture resistance of teeth with Class II bonded amalgam and new tooth-colored restorations.

This study compared the cuspal fracture resistance of posterior teeth restored with four different adhesive restorations. Fifty sound, maxillary human premolars were randomly divided into a control group and four experimental groups with 10 teeth in each. Specimens in the first group were intact teeth that were tested as unprepared. The remaining four groups received mesio-oclusodistal cavity preparations and were restored with a hybrid composite (Filtek Z250), a packable composite (Filtek P60), an ormocer (Definite) and an amalgam (SDI Permite) with an amalgam bonding agent (Amalgam Bond Plus). All groups were stored in water at 37 degrees C for 15 days and thermocycled 1000 times between 5 degrees-55 degrees C. The specimens were preloaded five times in compression to 10 kg using two metal rods that contacted only the teeth on the cuspal inclines. The teeth were then loaded occlusally in an Instron Universal Testing Machine until fracture occurred. The means of force required to fracture the teeth in each of the five groups was analyzed using one-way ANOVA and Tukey Test. The difference between the mean cuspal fracture resistance of the unprepared control teeth and those restored with amalgam groups was found to be statistically significant (p < 0.05). No significant differences in resistance to cuspal fracture were found among the restoration groups, the unprepared control group and those teeth restored with hybrid composite, packable composite and ormocer groups (p > 0.05).

The effect of different preparation and etching procedures on the microleakage of direct composite veneer restorations.

OBJECTIVES: The aim of this in vitro study was to compare the microleakage of direct composite veneer restorations prepared by a conventional dental bur or Er,Cr:YSGG (erbium, chromium doped yttrium scandium gallium garnet) laser and etched with different procedures. METHODS: Fifty maxillary incisor teeth prepared for direct veneers with gingival margins in dentin and incisal margins in enamel were randomly divided into five groups (n = 10): group 1 (control), prepared with diamond bur and etched with phosphoric acid; group 2, prepared with diamond bur and etched with Er,Cr:YSGG laser (Waterlase MD/Biolase); group 3, prepared with laser and not etched; group 4, prepared with laser and etched with phosphoric acid; and group 5, prepared and etched with laser. After the application of the etch and rinse adhesive system (Prime & Bond NT/Dentsply), teeth were restored with the nano ceramic restorative material (Ceram X Duo/Dentsply), subjected to thermocycling and immersed in 0.5% basic fuchsin dye for 24 h. The teeth were sectioned longitudinally and dye penetration was evaluated by a binocular stereomicroscope equipped with a measuring device. Data were analyzed by Kruskal-Wallis and Wilcoxon signed ranks tests. The level of significance was set at p = 0.05. RESULTS: Significant differences were observed in enamel of the five groups (p < 0.05). Minimal microleakage was observed in groups 1 and 3. The highest microleakage was evaluated in group 5 (p < 0.05). No significant differences were found among the five groups in dentin (p > 0.05). No differences were recorded between the microleakage values in enamel and dentin within each group and this was valid for all groups (p > 0.05). CONCLUSIONS: The results confirmed that enamel and dentin surfaces prepared with Er,Cr:YSGG laser for direct composite veneer restorations may provide comparable sealing.

Shear bond strength of composite bonded to erbium:yttrium-aluminum-garnet laser-prepared dentin.

The purpose of this study was to evaluate the dentin bond strength to resin composite following erbium:yttrium-aluminum-garnet (Er:YAG) laser preparation using different adhesive systems. Seventy dentin specimens prepared from human molar teeth were randomly assigned to seven groups of ten. The first five groups were prepared with an Er:YAG laser 2940 nm at the manufacturer's recommended settings and (1) acid etched, and etch-and-rinse adhesive Excite was applied; (2) Excite was applied; (3) two-step self-etching adhesive AdheSE was applied; (4) laser etched (120 mJ/10 Hz), and Excite was applied; (5) laser etched, and AdheSE was applied. The last two groups were added as controls (prepared with a diamond bur): (6) acid etched, and Excite was applied; (7) AdheSE was applied. Nanohybrid composite cylinders 4 mm x 2 mm were bonded to the dentin surfaces. After the specimens had been stored in distilled water and had undergone thermocycling, the shear bond strength was tested and the data were analyzed statistically. The Duncan multiple comparison test showed that specimens prepared with a diamond bur and with acid and Excite applied showed the highest mean bond strength (13.01 +/- 2.09 MPa), followed by those prepared with Er:YAG and with AdheSE applied (11.5 +/- 3.59 MPa) and those prepared with a diamond bur and with AdheSE applied (10.75 +/- 1.95 MPa), but there were no significant differences among them (P > 0.05). Er:YAG-prepared specimens, with acid, Excite (3.28 +/- 0.95 MPa) and specimens that were laser etched and with AdheSE applied (3.37 +/- 0.63 MPa) showed the lowest mean values for bond strength (P < 0.05). The results suggested that dentin surfaces prepared with Er:YAG laser may provide comparable composite resin bond strengths depending on the adhesives used.

Effect of different adhesive systems and laser treatment on the shear bond strength of bleached enamel.

PURPOSE: This study determined the shear bond strength of a nanohybrid composite resin to bleached enamel immediately or 15 days later using different adhesive systems and laser application. METHODS: One hundred and forty enamel specimens were prepared from human molar teeth and bleached either with 16% carbamide peroxide (CP) or 30% CP according to the manufacturer's (Vivastyle/Vivadent) recommendations. After bleaching treatments specimens were divided into two groups according to the treatment time of the adhesive procedures: immediately or 15 days after the bleaching treatments. The four groups were then divided into five subgroups due to the surface treatments: using a two-step self-etching adhesive (AdheSe, Ivoclar Vivadent G, Schaan, Liechtenstein) or a two-step etch and rinse adhesive (Excite, Ivoclar Vivadent G, Schaan, Liechtenstein) and application of laser prior to adhesive procedures or not. After adhesive procedures nanohybrid composite resin cylinders of 4 mm x 2 mm (Tetric Evo Ceram/Vivadent) were bonded to the enamel surfaces. All specimens were subjected to shear bond strength test after thermocycling and 24h of storage in water. Data were analyzed statistically. RESULTS: Mann-Whitney U-test analysis showed no significant difference in the mean bond strength values of enamel bleached with either 16% CP or 30% CP (p>0.05). There was no difference between the groups bonded immediately or 15 days after bleaching (p>0.05). Application of the etch and rinse adhesive after 15 days showed the highest bond strength values, whereas self-etching adhesive and laser application showed the lowest values in both bleaching treatments. CONCLUSIONS: The results suggested that following the bleaching treatments, the use of etch and rinse adhesive system may provide higher bond strengths than self-etching adhesive and laser application.

Shear bond strength of composite bonded to Er,Cr:YSGG laser-prepared dentin.

OBJECTIVE: The purpose of this in vitro study was to evaluate dentin bond strength to resin composite following high-speed rotary or Er,Cr:YSGG laser preparation using two different adhesive systems. MATERIALS AND METHODS: One hundred and forty dentin specimens were prepared from human molars. Seventy specimens were prepared with a high-speed diamond bur and 70 of the specimens were prepared with an Er,Cr:YSGG laser. Each group was subdivided into 7 groups of 10 teeth and etched with either 37% H3PO4, laser etched at two different power levels (1.25 W and 3 W), or not etched. Nano-hybrid composite resin cylinders 4 x 2 mm in size (Tetric EvoCeram, Vivadent) were bonded to the dentin surfaces with the application of an etch-and-rinse adhesive (Exite/Vivadent), or a self-etching adhesive (AdheSe/Vivadent). After storage in distilled water and thermocycling, a shear bond strength test was performed on all specimens and the data were statistically analyzed. RESULTS: ANOVA detected significant differences between the tested groups (p < 0.001). Duncan's multiple comparison test showed that Excite-applied specimens that were prepared with laser and laser etched (1.25 W or 3 W) had higher mean bond strengths. Both AdheSe- and Excite-applied specimens prepared with the diamond bur and laser etched (1.25 W) showed the lowest mean bond strength values (p < 0.05). CONCLUSION: The results suggest that dentin surfaces prepared with the Er,Cr:YSGG laser and etched with the laser (at either 1.25 or 3 W) may provide comparable or increased composite resin bond strengths, depending on the adhesive used.