Dental students' ability to assess their performance in a preclinical restorative course: comparison of students' and faculty members' assessments.

Dental education consists of both theoretical and practical learning for students to develop competence in treating patients clinically. When dental students encounter practical courses in their first year as a new educational experience, they must also learn to evaluate themselves. Self-evaluation is an essential skill to learn for dental professionals to keep increasing their competence over the course of their careers. The aim of this study was to compare the assessment scores of second- and third-year dental students and the faculty in two consecutive preclinical practical exams in restorative dentistry courses in a dental school in Turkey. Faculty- and student-assigned scores were calculated from two consecutive preclinical examinations on tooth restorations performed on both artificial casts and phantom patients. The students were formally instructed on grading procedures for tooth preparations, base and restoration placement, and polishing criteria. After each step, each item was assessed by faculty members, the student, and another student. The results indicated that the initial differences between second-year students' assessments of their own preclinical practical ability and that of the faculty decreased among the third-year students. Self-evaluation scores did not indicate whether the third-year students tended to over- or underestimate the quality of their own work. However, the second-year students not only overestimated themselves but thought they were above average. The results point to the need to develop students' self-insight with more exercises and practical training.

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.

Effect of operator variability on microleakage with different adhesive systems.

OBJECTIVE: The objective of this study was to evaluate the effect of operator variability on microleakage with different adhesive systems. MATERIALS AND METHODS: A total of 180 standardized Class V cavities were prepared on facial and lingual of 90 extracted human premolar teeth and randomly assigned to five groups according to the adhesive systems used (n = 36): Prime and Bond NT (PB), Single Bond (SB), Futura Bond NR, Xeno III (XE) and Adper Prompt-L-Pop (LP). The adhesive groups were then further subdivided into three operator groups according to level of clinical experience (n = 12): An undergraduate student, a research assistant and a faculty member. All cavities were restored with same composite resin. The restored teeth were thermocycled (500 cycles, 5-55°C) then immersed in 0.5% basic fuchsin and measured for leakage under a stereomicroscope. Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney U tests. RESULTS: Significant inter-operator variation was found in the enamel margins in the XE group with significantly higher microleakage when used by the undergraduate student (P < 0.05). Although no significant differences in microleakage were found between adhesive systems for the research assistant and faculty member (P > 0.05), significant differences were observed between PB and LP, PB and XE, SB and LP and SB and XE in the enamel margins for the undergraduate student (P < 0.05). CONCLUSION: Microleakage of adhesive systems is more dependent on interactions between the operator and adhesive material than on the choice of adhesive material.

Bond strength of one-step self-etch adhesives and their predecessors to ground versus unground enamel.

OBJECTIVE: The aim of this study was to compare the shear bond strength of several self-etch adhesives to their two-step predecessors to ground and unground enamel. METHODS: Seventy-five extracted, non-carious human third molar teeth were selected for this study. The buccal surfaces of each tooth were mechanically ground to obtain flat enamel surfaces (ground enamel), while the lingual surfaces were left intact (unground enamel). The teeth were randomly divided into five groups according to the adhesive systems (n=15): one-step self-etch adhesive - Clearfil S3 Bond, its two-step predecessor - Clearfil SE Bond, one-step self-etch adhesive - AdheSE One, and its two-step predecessor - AdheSE, and a two-step etch-and-rinse adhesive - Adper Single Bond 2(control). After application of the adhesives to the buccal and lingual enamel surfaces of each tooth, a cylindrical capsule filled with a hybrid composite resin (TPH) was seated against the surfaces. The specimens were stored in distilled water at 37°C for 24 hours, followed by thermocy-cling (5°C-55°C/500 cycles). They were subjected to shear bond strength test in a universal testing machine at a crosshead speed of 1.0 mm/minute. The data were compared using a two-way ANOVA, followed by Bonferroni test at P<.05. RESULTS: All adhesives exhibited statistically similar bond strengths to ground and unground enamel except for the etch-and-rinse adhesive that showed significantly higher bond strengths than the self-etch adhesives (P<.05). No significant differences in bond strength values were observed between ground and unground enamel for any of the adhesives tested (P=.17). CONCLUSION: Similar bond strengths to ground and unground enamel were achieved with one-step self-etch adhesives and their predecessors. Enamel preparation did not influence the bonding performance of the adhesives tested.

Clinical evaluation of a nanohybrid and a flowable resin composite in non-carious cervical lesions: 24-month results.

PURPOSE: To evaluate the 24-month clinical performance of cervical restorations using a nanohybrid and a flowable resin composite with a one-step self-etching adhesive. MATERIALS AND METHODS: Twenty-one patients with at least one pair of non-carious cervical lesions participated in this study. A total of 134 non-carious cervical lesions were restored (67 with a nanohybrid resin composite, Grandio; 67 with a flowable resin composite, Grandio Flow) using a one-step self-etching adhesive system, Futura Bond NR, by one dentist. The restorations were evaluated for retention, color match, marginal discoloration, marginal adaptation, surface texture, anatomic form, and secondary caries by two calibrated examiners at baseline and after 6, 12, and 24 months using modified USPHS criteria. The survival rates of the restorations were calculated by the Kaplan-Meier estimator. The comparison of resin composites for each category was performed with the Pearson chi-square test, and the performance of restorations at baseline and after each recall time was evaluated using McNemar's test (p < 0.05). RESULTS: All patients attended the 24-month recall. The retention rates at 6 months were 66% and 58%, and 61% and 57% at 12 months for Grandio and Grandio Flow, respectively. At the 24-month recall, the retention rate was 60% for Grandio and 54% for Grandio Flow. No statistically significant differences were found in retention rates among the restorative materials in any evaluation period (p > 0.05). For marginal discoloration and anatomical form, three Grandio and three Grandio Flow restorations showed Bravo scores at the end of 24 months. The restorations in both groups had Alfa ratings of 100% for the rest of the criteria evaluated. CONCLUSION: The nanohybrid and flowable resin composites showed similar clinical performances in the restoration of non-carious cervical lesions over 24 months.

Comparison of the Er,Cr:YSGG laser with a chemical vapour deposition bur and conventional techniques for cavity preparation: a microleakage study.

The aim of this study was to compare the effects of the Er,Cr:YSGG laser using chemical vapour deposition (CVD) bur cavity preparation with conventional preparation methods including a diamond bur and a carbide bur on the microleakage with two different adhesive systems. A total of 40 extracted human premolars were randomly assigned to four experimental groups according to the cavity preparation technique: group I diamond bur (Diatech); group II carbide bur (Diatech); group III Er,Cr:YSGG laser (Biolase Millennium II); and group IV CVD bur (CVDentUS). Using the different preparation techniques, Class V standardized preparations were performed on the buccal and lingual surfaces with gingival margins on the dentin and occlusal margins on the enamel. Each preparation group was randomly assigned to two subgroups (five teeth, ten preparations) according to the type of adhesive: an etch-and-rinse adhesive (Adper Single Bond), and a single-step self-etch adhesive (AdheSE One). All preparations were restored with a nanohybrid composite resin in a single increment. Following thermocycling (×500; 5-55°C), the teeth were immersed in basic fuchsin and sectioned in the orovestibular direction. Dye penetration was evaluated under a light microscope by two blinded examiners. Data were statistically analysed with the Kruskal-Wallis and Wilcoxon tests (p<0.05). There were no statistically significant differences between the preparation techniques with either of the two adhesive systems (p>0.05). Comparing the enamel and dentin leakage scores within each group, no statistically significant differences were found (p>0.05). The Er,Cr:YSGG laser cavity preparation did not differ from preparation with CVD, diamond or carbide bur in terms of microleakage with the different adhesive systems.

The effects of different light-curing units on the clinical performance of nanofilled composite resin restorations in non-carious cervical lesions: 3-year follow-up.

PURPOSE: To compare the effects of quartz-tungsten-halogen (QTH) and light-emitting-diode (LED) curing units on the 3-year clinical performance of a nanofilled composite resin in noncarious cervical lesions. MATERIALS AND METHODS: Twenty-six patients with at least 2 noncarious cervical lesions were enrolled in the study. A total of 154 restorations were placed: half polymerized with QTH and half polymerized with LED. Single Bond was used as the adhesive and Filtek Supreme was used as the restorative material for all restorations. The restorations were assessed by two different examiners using modified Ryge/USPHS criteria at baseline and at 6, 12, 24, and 36 months. The survival rates were analyzed with the Kaplan-Meier estimator and the Log-Rank test, and the statistical analysis was completed using Pearson's chi-square test (p < 0.05). RESULTS: Twenty patients were available for recall after 3 years and 114 restorations were evaluated (recall rate of 74%). The survival rate was 84% for QTH and LED polymerized restorations. There were no statistically significant differences in survival rates between the light-curing units (p > 0.05). No significant differences were observed between QTH and LED polymerized restorations in terms of any of the evaluation criteria at the end of 3 years (p > 0.05). No color change in the restorations was observed and none of them exhibited secondary caries at the end of 3 years. CONCLUSION: Over the 3-year study period, both curing units, QTH and LED, produced acceptable clinical results in noncarious cervical lesions.

Effect of different pretreatment methods on dentin bond strength of a one-step self-etch adhesive.

AIM: The aim of this in vitro study was to evaluate the shear bond strength of a one-step self-etch adhesive to dentin pretreated with phosphoric acid, air abrasion, or laser. METHODS AND MATERIALS: Fifty-six extracted non-carious human mandibular molars were mounted and the occlusal surfaces ground with a mechanical grinder to obtain flat occlusal dentin surfaces. The teeth were randomly divided into four groups of 14 teeth according to the different dentin surface pretreatment methods: Group I--acid, Group II--laser, Group III--air abrasion, Group IV (control)--no surface treatment. After applying a one-step self-etch adhesive system, Futura Bond NR, cylinders of Z250 composite resin were bonded to the dentin surfaces by transparent gelatin capsules (2.5 mm diameter; 3 mm high) and then polymerized. All specimens were stored in distilled water at 37 masculineC for 24 hours. Shear bond testing was carried out using an Universal testing machine with a crosshead speed of 0.5 mm/sec. Data were analyzed using the Kruskal Wallis and Mann-Whitney tests at a significance level of 0.05. RESULTS: The bond strength of air abrasion (Group III) and the control group (Group IV) were statistically higher than both the acid (Group I) and laser (Group II) pretreatments (p < 0.05). No statistically significant differences were found in shear bond strength between surfaces treated with air abrasion and the control group (p > 0.05). Surfaces pretreated with laser (Group II) resulted in the lowest bond strength which was not statistically different from those pretreated with acid (Group I) (p > 0.05). CONCLUSION: Surfaces pretreated with acid and laser adversely affected the bond strength of a one-step self-etch adhesive, Futura Bond NR, while pretreatment with air abrasion had no effect on bond strength. CLINICAL SIGNIFICANCE: The pretreatment of dentin surfaces prior to self-etch adhesive seems to be unnecessary and defeats the original purpose of these systems.

Effects of different light curing units/modes on the microleakage of flowable composite resins.

OBJECTIVES: The aim of this in vitro study was to evaluate the influence of different light curing units and modes on microleakage of flowable composite resins. METHODS: Eighty Class V cavities were prepared in buccal and lingual surfaces of 40 extracted human premolars with cervical wall located in dentin and the occlusal wall in enamel. These teeth were randomly assigned into two groups (n=20) and restored with different flowable composites; Group I: Esthet-X Flow, Group II: Grandio Flow. Each group was randomly divided into four subgroups; while the samples of the first subgroup were polymerized with conventional Halogen light, the rest of them were polymerized with different curing modes of Light Emitting Diode (LED). The second subgroup was polymerized with fast-curing; the third subgroup with pulse-curing and those of the fourth subgroup with step-curing modes of LED. After the samples were thermocycled and immersed in dye, they were longitudinally sectioned. Dye penetration was assessed under a stereomicroscope. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests. RESULTS: None of the restorations showed leakage on enamel margins. On dentin margins no significant differences were observed between flowable composite resins polymerized with halogen light (P>.05). While step curing mode of LED presented significant differences between the resins, the difference was insignificant when fast-curing and pulse-curing mode of LED were used. No statistically significant differences were observed between curing units for Esthet-X Flow samples. For Grandio Flow samples, only step-curing mode of LED caused statistically higher leakage scores than halogen and other curing modes of LED (P<.05). CONCLUSIONS: The effect of curing units' type and curing mode on flowable composite resin leakage might be material-dependent.

The effect of curing units and staining solutions on the color stability of resin composites.

This study investigated the effects of two different light curing units and two staining solutions on the color stability of a hybrid composite and a nanohybrid composite after different immersion periods. Thirty disk-shaped specimens (10 mm in diameter, 2-mm thick) were fabricated for each of the resin composites, Clearfil AP-X and Filtek Supreme. The specimens were randomly divided into two groups according to the curing unit used: Group I specimens (n = 15) were cured with a quartz-tungsten-halogen (QTH) light for 40 seconds, and Group II specimens (n = 15) were cured with a light-emitting diode (LED) unit in standard mode for 40 seconds. The specimens were incubated in 100% humidity at 37 degrees C for 24 hours. Then, the baseline color values (L*, a*, b*) of each specimen were measured with a spectrophotometer according to the CIELab color scale. After baseline color measurements, five randomly selected specimens from each group (Groups I and II) were immersed in one of two staining solutions (tea or coffee) or distilled water (control). After 1, 7 and 30 days of immersion, the color values of each specimen were remeasured and the color change value (deltaE*ab) calculated. Color changes caused by immersion in tea and coffee for 30 days were only perceptible in the Clearfil AP-X specimens cured with QTH or LED. In the Filtek Supreme specimens, coffee perceptibly stained the teeth after all immersion periods and tea stained after 30 days. Polymerization with QTH or LED did not cause any significant difference in the color stability of Clearfil AP-X or Filtek Supreme. While there were no significant differences between staining solutions in the Clearfil AP-X specimens cured with LED after one and seven days of storage and one day of storage in the QTH cured specimens, significant differences were observed between water and coffee after seven days of storage. In the Filtek Supreme specimens cured with QTH or LED, there were statistically significant differences between the staining solutions after one and seven days of storage. After 30 days of storage, no significant difference was found between tea and coffee in either resin composite cured with QTH or LED. The effect of the staining solutions (tea, coffee) on color changes in composites was immersion time and resin-material dependent.

The effect of desensitizing treatments on the bond strength of resin composite to dentin mediated by a self-etching primer.

This study evaluated the bond strength of resin composite to dentin, mediated by a self-etching adhesive, following the application of various dentin desensitizing treatments and artificial saliva storage. The buccal cervical areas of 24 extracted human third molars were ground flat to expose cervical dentin. The dentin surfaces were polished with 1200-grit SiC paper, then the teeth were randomly assigned to six groups, five desensitizing treatments and one control: Group I-VivaSens; Group II-Fluor Protector; Group III-Isodan; Group IV-Futura Bond NR; Group V-Nd:YAG laser and Group VI-Control (without application of a desensitizing agent). After applying the desensitizing treatments and storing the molars in artificial saliva for 14 days at 37 degrees C, Futura Bond NR was used to bond resin composite to dentin. TPH composite build-ups were constructed incrementally to a height of 5 mm. The teeth were sectioned to obtain bonded slices of 0.7 mm thick specimens containing the resin-composite joint. The specimens were then trimmed into an hourglass shape and subsequently subjected to microtensile testing at a crosshead speed of 1 mm/minute. The data were analyzed using the Kruskal-Wallis analysis and multiple comparisons test. The control (Group VI) and Futura Bond NR self-etching treatment (Group IV) group yielded statistically significant higher bond strength values than the other desensitizing treatment groups tested (p < 0.005). While pretreatment of dentin surfaces with desensitizing agents (Fluor Protector, VivaSens and Isodan) and laser (Nd:YAG) reduced the bond strength values of the resin composite, higher bond strengths were achieved using a self-etching adhesive (Futura Bond NR) as a desensitizing agent.

The effect of saliva contamination on microleakage of an etch-and-rinse and a self-etching adhesive.

PURPOSE: To evaluate the effect of saliva contamination on the microleakage of an etch-and-rinse adhesive and a self-etching adhesive. MATERIALS AND METHODS: Class V cavity preparations at the cementoenamel junction were made on the buccal and lingual surfaces of 40 freshly extracted human molars. The teeth were randomly assigned into two groups for different adhesives: Group I, Single Bond (two-step etch-and-rinse adhesive) and Group II, Futura Bond NR (one-step self-etching adhesive). The adhesive materials were applied according to their manufacturers' recommendations. The specimens were then further subdivided into five subgroups (A-E; n = 8): group A, contamination before adhesive curing; group B, contamination before adhesive curing and re-application of adhesive; group C, contamination after adhesive curing; group D, contamination after adhesive curing and re-application of adhesive; and group E, no contamination (control). Contamination of adhesive surfaces was performed with fresh natural saliva and the saliva was removed by a gentle air blast. The specimens were restored with Z250 hybrid composite. After thermocycling (500x, 5 degrees C to 55 degrees C) and immersion in 0.5% basic fuchsin, the dye penetration was evaluated under a stereomicroscope. Statistical analysis was performed with the Kruskal-Wallis test at p < 0.05. RESULTS: No statistically significant differences were found among the contamination subgroups on the enamel or on the dentin for either group (p > 0.05). There was no significant difference in leakage between Group I and Group II for any subgroup (p > 0.05). CONCLUSION: Contamination of adhesives with saliva before and after adhesive curing did not worsen the microleakage of the two-step etch-and-rinse adhesive Single Bond or the one-step self-etching adhesive Futura Bond NR.

A two-year clinical evaluation of pit and fissure sealants placed with and without air abrasion pretreatment in teenagers.

BACKGROUND: Long-term retention of pit and fissure sealants is essential for their success. The aim of this study was to compare the retention rates of sealants placed with acid-etching and air abrasion followed by acid etching. METHODS: Sixteen subjects aged 16 and 17 years were included in the study. Using a half-mouth design, the authors performed fissure preparation with phosphoric acid gel on randomly assigned maxillary and mandibular permanent premolars and molars from one side of the mouth (Group I) and performed air abrasion followed by acid etching on the contralateral side of the mouth (Group II). The authors applied sealant material on 162 teeth, and they evaluated the sealants as complete retention, partial loss or total loss at six, 12 and 24 months. RESULTS: While fissure sealant retention rates were not significantly different for the two techniques at six months (P = .97), the retention rates for the teeth in Group II were significantly higher at 12 (P = .025) and 24 months (P = .002). Molar retention rates were significantly less than those for premolars at each evaluation period (P < .05). CONCLUSION: The sealant retention rates at 12 and 24 months were higher in Group II (air abrasion followed by acid etching). CLINICAL IMPLICATIONS: As air abrasion followed by acid etching resulted in significantly higher sealant retention rates, this method could be a good choice for fissure preparation before sealant placement for long-term success.

Antibacterial activity of different generation dentin-bonding systems.

OBJECTIVES: The aim of this in vitro study was to investigate the antibacterial activities of different generation dentin-bonding systems. METHOD AND MATERIALS: The antibacterial activities of dentin-bonding systems Optibond FL Primer, Single Bond, Clearfil SE Bond Primer, and Prompt-L-Pop were evaluated against Streptococcus mutans, Streptococcus salivarius, Lactobacillus casei, and Lactobacillus acidophilus. Cervitec (1% chlorhexidine varnish) was also examined as a positive control material. Disk diffusion tests with filter paper disks (n = 10) containing a drop of each material (20 microL) were used. After incubation at 37 degrees C for 48 hours, the growth inhibition zones were measured in millimeters. RESULTS: Of all the materials tested, Optibond FL Primer, Clearfil SE Bond Primer, and Prompt-LPop showed larger growth inhibition zones than the control material for all bacterial strains. No antibacterial effect was noted for Single Bond. The results indicated that Optibond FL Primer had the strongest effect against the S mutans and L casei, and Clearfil SE Bond Primer produced the largest inhibition zone for S salivarius and L acidophilus among the test materials. CONCLUSION: The antibacterial effects observed for the tested different generation dentin-bonding systems may be related to the acidic nature of the materials.

The effect of different types of flowable restorative resins on microleakage of Class V cavities.

This study evaluated the microleakage of Class V cavities restored with three different types of flowable resin restorative material and compared the effects of using their respective manufacturer's dentin adhesive or a different brand. Class V cavities with the occlusal margin in enamel and the gingival margin in dentin were prepared on the buccal and lingual surfaces of 48 non-carious human molars. The teeth were randomly assigned to three equal groups of 16. The first eight teeth in each group were restored with one of the flowable restorative materials (Filtek Flow, Dyract Flow, Admira Flow) using the manufacturer's recommended dentin adhesive (Single Bond, Prime & Bond NT, Admira Bond), and the remaining eight molars were restored using a different brand of dentin adhesive (Gluma Comfort Bond). The samples were thermocycled 200 times (5 degrees C-55 degrees C) with a one-minute dwell time. They were then immersed in a 2% basic fuchsin solution for 24 hours, sectioned and analyzed by stereomicroscopy. There was no statistically significant difference at the occlusal margins for either restoration used with its respective dentin adhesive. At the gingival margins, there was a significant difference among all groups. Flowable ormocer (Admira Flow/Admira Bond) displayed the least leakage at the gingival margins. When these flowable restoratives were used with a different brand of dentin adhesive, statistically significant differences were observed both on enamel and dentin. None of the restoratives tested fully prevented leakage at the gingival margins. No significant differences in microleakage were observed among the restorative materials used with respect to the manufacturer's dentin adhesive or a different brand except for Admira Flow restorative at the gingival margins. The gingival margins had significantly more microleakage than the occlusal margins (p < 0.05) except in the Admira Flow group, where microleakage at the occlusal and gingival margins was almost equal.

The effect of flowable resin composite on microleakage in class V cavities.

This in vitro study investigated the microleakage of flowable resin composite as a restorative material and as a liner (either light cured separately or co-cured with hybrid resin composite) in Class V cavities. A light-cured hybrid resin composite was used as a control. Twenty extracted human premolars were prepared with standardized Class V cavity outlines on the buccal and lingual surfaces. The occlusal margin of the cavities was on enamel and the gingival margin was on dentin. One bottle adhesive system (Single Bond) was used after etching enamel and dentin with 34.5% phosphoric acid for 15 seconds. The cavities were randomly divided into four groups of 10 each and restored according to the manufacturers' instructions: Group I-Hybrid resin composite (Z100); Group II-Flowable resin composite (Filtek Flow); Group III-Flowable resin composite (Filtek Flow)+Hybrid resin composite (Z100); light cured separately; Group IV-Flowable resin composite (Filtek Flow)+Hybrid resin composite (Z100); co-cured. The samples were thermocycled 200 times with a 30-second dwell time. They were then immersed in a 0.5% basic fuchsin solution for 24 hours, sectioned and analyzed by stereomicroscopy. The degree of dye penetration was recorded and analyzed with the Kruskal-Wallis and Mann-Whitney U tests. The results of this study indicate that there was no leakage at the occlusal margin for either restoration. Statistically significant differences were found among the groups at the gingival margin. No statistically significant difference was observed between the occlusal and gingival margins except in Group IV. The combination of flowable resin composite and hybrid composite light cured separately yielded the best result in this study. The most leakage was observed when this combination was co-cured. The resistance to microleakage of flowable resin composite as a restorative material is similar to that of hybrid resin composite.

A scanning electron microscopic study of different caries removal techniques on human dentin.

Scanning electron microscopy (SEM) evaluated the effect of different caries removal techniques on human dentin topography. Thirty-six extracted human carious mandibular molars were randomly assigned to six groups according to caries removal technique. Carious tissue was removed by hand excavation, bur excavation, air-abrasion, laser ablation, chemomechanical methods and sono-abrasion. The remaining dentin surfaces were replicated and gold-coated. The surfaces were examined using SEM and distinct differences in appearance were observed among specimens treated with different caries removal techniques. While hand-excavated, bur-excavated and air-abraded carious dentin surfaces were covered with a residual smear layer, sono-abrasion with patent dentinal tubules completely removed the smear layer. A few patent orifices of dentinal tubules were observed in dentin subjected to laser ablation and chemo-mechanical caries removal.

The effect of current-generation bonding systems on microleakage of resin composite restorations.

OBJECTIVE: The aim of this study was to determine the microleakage of current-generation dentin bonding systems in Class II resin composite restorations. METHOD AND MATERIALS: Class II (occlusodistal or occlusomesial) cavity preparations with a gingival margin 2 mm apical to the cementoenamel junction were prepared on 70 noncarious, extracted human premolar teeth. Teeth were randomly divided into five groups and treated with different-generation bonding systems (Optibond FL, Gluma One Bond, Clearfil SE Bond, acid etching plus Clearfil SE Bond, and Prompt-L-Pop). All cavities were restored in a posterior resin composite and subjected to 200 thermocycles (at 5 degrees C to 55 degrees C; 30-second dwell time). After immersion in 0.5% basic fuchsin dye for 24 hours, the teeth were sectioned longitudinally and evaluated for dye penetration using a binocular stereomicroscope. RESULTS: There was no statistically significant differences among bonding systems in the degree of microleakage in the occlusal walls. For gingival walls, statistically significant differences were found only between the Clearfil SE Bond and Prompt-L-Pop groups and the Clearfil SE Bond with acid etching and Prompt-L-Pop groups. The greatest microleakage was observed in Prompt-L-Pop specimens. CONCLUSION: Most of the tested dentin bonding systems were able to eliminate microleakage completely in the occlusal walls, but some systems exhibited statistically significant differences in leakage in the gingival walls.