Volumetric Evaluation of Void/Gap Formation and Microleakage Cementing Fiber Posts on Extracted Teeth with Three Different Cements.

PURPOSE: To evaluate microleakage in roots restored with fiber posts cemented using three different luting cements, to measure the volume of voids/gaps within the obturated/postcemented root canals, and to examine whether microleakage and the volume of voids/gaps were correlated. MATERIALS AND METHODS: Thirty-six extracted human mandibular incisors were decoronated, and the root canals were obturated using gutta-percha and sealer in the experimental groups (n = 30). Six roots were used as controls. A standard post space was prepared, and an identically sized fiber post was cemented in each experimental specimen using one of three luting cements (Panavia F2.0, Bifix SE, GC FujiCEM; n = 10 each). The specimens were scanned using micro-computed tomography, and the volume of voids/gaps was determined. The specimens were then subjected to a fluid filtration assay to evaluate microleakage. RESULTS: The volume of voids/gaps was significantly lower in the GC FujiCEM group, and significantly less microleakage occurred in the Bifix SE group compared with other groups (both p < 0.001). A significant correlation between the volume of voids/gaps and leakage was found only in the Panavia F2.0 group (p = 0.003; r = 0.830). No such correlation was found in the analysis of all groups combined. CONCLUSIONS: The group with the greatest volume of voids/gaps (Bifix SE) showed the least microleakage, and the group with the smallest volume of voids/gaps (GC FujiCEM) showed the most microleakage. Panavia F2.0 ranked between and exhibited significant correlation.

Clinical evaluation of combined surgical/ restorative treatment of gingival recession-type defects using different restorative materials: A randomized clinical trial.

BACKGROUND/PURPOSE: An ideal therapeutic procedure for the treatment of gingival recession associated with an NCCL has presented a challenge to clinicians. Various dental materials and surgical approaches have been used to manage gingival recessions associated with NCCLs for the most predictable combined surgical/restorative treatment. The objective of this study was to evaluate the treatment of gingival recessions associated with non-carious cervical lesions (NCCL) using a modified coronally advanced flap (MCAF) in combination with a connective tissue graft (CTG) on restored root surfaces. MATERIALS AND METHODS: Twenty-three systemically healthy subjects, who were positive for the presence of three cervical lesions associated with gingival recessions in three different adjacent teeth, were enrolled in the study. The NCCL were each restored prior to surgery by using one of three different materials: nanofilled composite resin (NCR), resin-modified glass ionomer cement (RMGI) or giomer. The gingival recession defects were treated by CTG. RESULTS: Inter-group differences were not statistically significant for probing depth (PD), relative recession height (rRH), relative clinical attachment level (rCAL), keratinized tissue width (KTW) or keratinized tissue thickness (KTT) (p > 0.05) among the groups at any time. The mean percentage of defect coverage was 71.18 ± 23.16% for NCR + CTG group; 71.33 ± 22.33% for RMGI + CTG group; and 64.23 ± 20.33% for giomer + CTG group at 1 year postoperatively (p > 0.05). CONCLUSION: The combined surgical/restorative treatments provided successful clinical results. Giomer + CTG may be less effective compared to other groups for treatment of gingival recession associated with NCCL.

Investigation of eluted monomers from resin-based root canal sealer by high-performance liquid chromatography analysis.

OBJECTIVE: The purpose of the current study was to determine the amount of urethane dimethacrylate (UDMA), bisphenol A-glycidyl methacrylate (Bis-GMA), poly (ethylene glycol) dimethacrylate (PEGDMA), bisphenol A ethoxylated dimethacrylate (Bis-EMA), and 2-hydroxyethyl methacrylate (HEMA) eluted from resin-based root canal sealer, epiphany, using high-performance liquid chromatography (HPLC). MATERIALS AND METHODS: Epiphany was placed into the plastic molds and light-cured with a light emitting diode. After the curing process, each specimen in the first group (n = 12) was immersed in Eppendorf tubes containing a phosphate-buffered saline solution (PBS) and incubated for 45 s. In the second group, each specimen (n = 12) was immersed in Eppendorf tubes containing PBS and incubated for 24 h. Of the specimen extracts, 100 µL were subjected to HPLC. Analysis of data was accomplished with one-way analysis of variance (P < 0.05). RESULTS: All of the samples eluted HEMA, UDMA, Bis-GMA, PEGDMA, and Bis-EMA. A significant difference was determined between the time periods of HEMA, UDMA, PEGDMA, and Bis-EMA (P < 0.05). CONCLUSION: The results of the current study showed that Epiphany releases HEMA, UDMA, Bis-GMA, PEGDMA, and Bis-EMA in both time periods.

An in vitro evaluation of the effects of desensitizing agents on microleakage of Class V cavities.

BACKGROUND: The aim of this study was to evaluate the effect of a desensitizing agent on microleakage of Class V cavities. MATERIAL AND METHODS: 72 premolar teeth were used. There were 6 groups. Class V restorations were prepared with two different restorative materials (Equia fil, GC, America and Grandio, VOCO, Germany) and two adhesive systems (Clearfil SE Bond, Kuraray, Japan and S3 Bond Plus, Kuraray, Japan) with and without desensitizing agent (Gluma Desensitizer, Heraeus Kulzer, Germany). Restorations were polished with aluminum oxide abrasive discs. Then a range of 5 - 55C thermocycling was performed 10.000 times. The microleakage of restorations was examined with dye penetration method (Basic fuchsine). Bonferroni corrections and Kruskal-Wallis test were used to determine the significance of differences in occlusal and gingival dye penetration scores between groups. RESULTS: There was no stastistical significance between the occlusal and gingival microleakage scores within the groups were shown. CONCLUSIONS: It can be concluded that use of desensitizing agent under both high viscosity glass ionomer restorative materials and resin composites doesn't affect the microleakage. KEY WORDS: High viscosity glass ionomer cement, composite resin, desensitizing agent, microleakage.

Two-year clinical evaluation of three adhesive systems in non-carious cervical lesions.

OBJECTIVES: Adhesive systems are continuously being introduced to Dentistry, unfortunately often without sufficient clinical validation. The aim of this study was to evaluate the clinical performance of cervical restorations done with three different adhesive systems. MATERIAL AND METHODS: 158 non-carious cervical lesions of 23 patients were restored with a nanofilled composite resin (Filtek Supreme, 3M/ESPE) combined with Single Bond (3M/ESPE, group SI), Clearfil SE (Kuraray Medical Inc., group CL) and Xeno III (De Trey Dentsply, group XE). In groups SI-B, CL-B and XE-B, the outer surface of the sclerotic dentin was removed by roughening with a diamond bur before application of the respective adhesive systems. In groups CL-BP and XE-BP, after removal of the outer surface of the sclerotic dentin with the bur, the remaining dentin was etched with 37% phosphoric acid and the self-etch adhesive systems Clearfil SE and Xeno III were applied, respectively. Lesions were evaluated at baseline, and restorations after 3 months, 1 year and 2 years using modified USPHS criteria. RESULTS: After 2 years, no significant difference was found between the retention rates of the groups (p >0.05). Although groups CL and SI showed significantly better marginal adaptation than group XE (p<0.05) at 2 years, no significant difference was found between the marginal adaptation of the groups SI-B, CL-B and XE-B (p>0.05). After 2 years no significant difference was observed among the marginal staining results of all groups (p>0.05). CONCLUSION: Although all adhesive systems showed similar retention rates, Clearfil SE and Single Bond showed better marginal adaptation than Xeno III after 2 years of follow-up.

Two-year clinical evaluation of three adhesive systems in non-carious cervical lesions

OBJECTIVES: Adhesive systems are continuously being introduced to Dentistry, unfortunately often without sufficient clinical validation. The aim of this study was to evaluate the clinical performance of cervical restorations done with three different adhesive systems. MATERIAL AND METHODS: 158 non-carious cervical lesions of 23 patients were restored with a nanofilled composite resin (Filtek Supreme, 3M/ESPE) combined with Single Bond (3M/ESPE, group SI), Clearfil SE (Kuraray Medical Inc., group CL) and Xeno III (De Trey Dentsply, group XE). In groups SI-B, CL-B and XE-B, the outer surface of the sclerotic dentin was removed by roughening with a diamond bur before application of the respective adhesive systems. In groups CL-BP and XE-BP, after removal of the outer surface of the sclerotic dentin with the bur, the remaining dentin was etched with 37% phosphoric acid and the self-etch adhesive systems Clearfil SE and Xeno III were applied, respectively. Lesions were evaluated at baseline, and restorations after 3 months, 1 year and 2 years using modified USPHS criteria. RESULTS: After 2 years, no significant difference was found between the retention rates of the groups (p >0.05). Although groups CL and SI showed significantly better marginal adaptation than group XE (p<0.05) at 2 years, no significant difference was found between the marginal adaptation of the groups SI-B, CL-B and XE-B (p>0.05). After 2 years no significant difference was observed among the marginal staining results of all groups (p>0.05). CONCLUSION: Although all adhesive systems showed similar retention rates, Clearfil SE and Single Bond showed better marginal adaptation than Xeno III after 2 years of follow-up.

Effect of different disinfectant methods on the initial microtensile bond strength of a self-etch adhesive to dentin.

The aim of this in vitro study was to evaluate the effect of different disinfection methods on the initial microtensile bond strength of a two-step, self-etch adhesive to dentin. Twenty mandibular molars were sectioned parallel to the occlusal plane to expose the mid-coronal dentin. All of the teeth were divided into four groups (n = 5 per group): (1) in group OZ, the dentin surfaces were exposed to ozone gas from the Ozonytron X delivery system (OzonyTron X-Bioozonix, Munich, Germany), (2) in group ND, the dentin surfaces were irradiated with an Nd:YAG laser (Pulsmaster 600 IQ, American Dental Technologies, U.S.), (3) in group CHX, the dentin surfaces were treated with a 2% chlorhexidine solution, and (4) in the control group, no treatment was applied. In all of the groups, the teeth were restored with Clearfil SE Bond (Kuraray, Tokyo, Japan) and Clearfil Majesty Posterior (Kuraray, Tokyo, Japan), according to the manufacturer's instructions. The teeth were sectioned perpendicular to the bonded surface (surface area of approximately 1 mm(2)). Thus, six to seven specimens were obtained from each tooth, and a total of 34 specimens were analyzed in each group. The specimens were attached to the microtensile test machine (Micro Tensile Tester, T-61010 K, Bisco, U.S.). The data was analyzed using the one-way analysis of variance (ANOVA) and Tukey test (p < 0.05). Fracture modes of each specimen were determined using a stereomicroscope (SZ-PT Olympus, Tokyo, Japan) and a scanning electron microscope (SEM). The lowest bond strength occurred in the OZ group. Significant differences were determined only between group OZ and the other groups (group ND, group CHX, and control group) (p < 0.05). In conclusion, although ozone decreased the microtensile bond strength of the self-etch adhesive system to dentin, the Nd:YAG laser and 2% chlorhexidine did not change the microtensile bond strength so in context of the present study it would appear that the Nd:YAG laser and 2% chlorhexidine may be used as pre-restorative sterilization procedures on the dentin prior to the application of a two-step, self-etch adhesive.

The effect of cavity shape and hybrid layer on the stress distribution of cervical composite restorations.

OBJECTIVES: The aim of this finite elemental stress analysis study was to evaluate the effect of cavity shape and hybrid layer on the stress distribution of the mandibular premolar tooth under occlusal loading. METHODS: The mandibular premolar tooth was selected as the model based on the anatomical measurements suggested by Wheeler. Four different mathematical models were evaluated: 1) a saucer-shaped non-carious cervical lesion restored with a composite without a hybrid layer, 2) a saucer-shaped non-carious cervical lesion restored with a composite with a hybrid layer, 3) a wedge-shaped non-carious cervical lesion restored with a composite without a hybrid layer, and 4) a wedge-shaped non-carious cervical lesion restored with a composite with a hybrid layer. A 200 N force was applied from the buccal tubercule and central fossa of the premolar tooth. The findings were drawn by the SAPLOT program. RESULTS: In models 2 and 4, the output showed that a hybrid layer acts as a stress absorber. Additionally, when the cavity shape was changed, the stress distribution was very different. CONCLUSIONS: Cavity shape and hybrid layer play an important role in stress distribution in cervical restorations.

Antibacterial activity of Propolis versus conventional endodontic disinfectants against Enterococcus faecalis in infected dentinal tubules.

INTRODUCTION: The antibacterial activity against Enterococcus faecalis of 2 propolis samples was investigated in a dentin block model, and their effectiveness was compared with that of established endodontic disinfectants, chlorhexidine (CHX) and calcium hydroxide [Ca(OH)(2)]. METHODS: Standardized dentin blocks were infected with E. faecalis ATCC 29212. The root canal space was filled with one of the ethanolic extracts of propolis (Artvin or Tekirdag mix [TM]), CHX 2%, Ca(OH)(2), or ethanol or phosphate-buffered saline for control. Canal dentin was sampled after 1 or 7 days by using a standard-size bur. The dentinal shavings were vortexed vigorously in phosphate-buffered saline, and aliquots were cultured on tryptone soy agar plates. Colonies were counted after 2 days of incubation. Statistical significance was set to 5%. RESULTS: All experimental agents significantly reduced the number of the cultivable bacteria. CHX was the most potent disinfectant at both times. Compared with the ethanol control, no significant reduction in the number of colonies was found for the propolis extracts at day 1; however, significant reduction was found at day 7. The 2 propolis samples were statistically similar to each other and to Ca(OH)(2), but the TM sample was also similar to CHX at day 7. This has been linked to the greater concentration of flavonoids, a group of antibacterially active compounds, in the TM sample as determined by gas chromatography-mass spectrometry analysis. CONCLUSIONS: The antimicrobial activity of the propolis samples tested in this study was between Ca(OH)(2) and CHX. Both propolis samples were antimicrobially effective; however, their activity did not exceed CHX.

Effect of hybrid layer and thickness on stress distribution of cervical wedge-shaped restorations.

OBJECTIVES: The aim of this finite elemental stress analysis study was to evaluate the effect of a hybrid layer and the hybrid layer thickness on the shear stress distribution in mandibular premolar teeth under occlusal loading. METHODS: The mandibular premolar tooth was selected based on the anatomical measurements suggested by Wheeler. The analysis was performed with a computer with the SAP 2000 structural analysis program. Three different mathematical models were evaluated; 1) composite restoration without a hybrid layer 2) composite restoration with a 1.5 mum thick hybrid layer and 3) composite restoration with a 3 mum thick hybrid layer. A total of 200 N of occlusal loading force was simulated from the buccal tubercule and central fossa of the premolar tooth. The findings were drawn by the Saplot program. RESULTS: In model B, the output showed that hybrid layer reduced the shear stress concentration especially on gingival margin of the composite. Similarly shear stress intensity was decreased by a thick hybrid layer in model C, especially on the gingival margin of the composite. CONCLUSIONS: The hybrid layer and its thickness plays an important role on stress distribution and intensity in cervical restorations.

Effect of multiple consecutive adhesive coatings on microleakage of class v cavities.

OBJECTIVES: The purpose of this in vitro study was to evaluate the effect of multiple consecutive adhesive coatings of a one-step self-etch adhesive on microleakage of Class V cavities. METHODS: Standardized box shaped Class V cavities were prepared onto the buccal side of forty five non-carious human premolar teeth. The teeth were randomly divided into three groups of fifteen teeth in each and restored as: Group I- one-step self-etch adhesive resin (Clearfil S3, Kuraray Co. Ltd., Osaka, Japan) was applied according to the manufacturer's instructions, Group II- two consecutive same one-step self-etch adhesive application was performed, and Group III- three consecutive same one-step self-etch adhesive application was performed. After the adhesive applications light curing unit was activated for 20 seconds and the cavities were restored with a composite resin. The restorations were finished with aluminum oxide discs and the specimens were stored in water at room temperature for 24 hours before they were immersed in 2% methylene blue for 48 hours. The dye penetration was examined under a stereomicroscope and the asymtotic significance were analysed with Kruskall Wallis and Mann Whitney U tests and dentin-enamel margins were compared with each other with Wilcoxon Signed Rank test. RESULTS: The microleakage at the dentinal margins of Class V cavities were significantly decreased with two (Group II) and three (Group III) consecutive adhesive applications (P<.05). There was no significant difference between Group I, Group II and Group III at the enamel margins (P<.05). The microleakage at the dentinal margins were significantly higher than the enamel margins in Group I and Group II but in Group III there was no statistically significant difference (P<.05). CONCLUSIONS: Within the limitations of this in vitro study, it may be concluded that three consecutive applications of the one-step self-etch adhesive resin provided better sealing than the one coat of adhesive resin at the dentinal margins of Class V cavities.

Examination of gutta-percha cones for microbial contamination during chemical use

OBJECTIVE: The aim of this study was to evaluate the degree of microbial contamination in packaged gutta-percha cones before and during use in clinical conditions. MATERIAL AND METHODS: Sealed packages of #15-40 gutta-percha cones were opened under aseptic laboratory conditions. Two gutta-percha cones from each size were randomly drawn and added to tubes containing glass beads and 750 µL of saline. The tubes were vortexed, serially diluted and samples of 250 µL were cultured on agar plates. The plates were incubated at 37ºC for 3 days and colonies were counted. The initially sampled packages were distributed to 12 final year dental students. The packages were collected at the end of the first and the third clinical practice days and sampled as described above. RESULTS: Baseline microbial counts did not exceed 3 CFU. At the end of the first and the third day, additional contamination was found in five and three of the packages, respectively. The ratio of contaminated packages at the first day and the third day was not significantly different (z-test; p > 0.05). The numbers of microorganisms cultured at the first day (8 ± 9.9 CFU) and the third day (4.5 ± 8.3 CFU) were not significantly different (Wilcoxon signed-rank test; p > 0.05). No significant correlation was found between the number of filled root canals and cultured microorganisms at either the first day (Spearman's rho; r = 0.481, p = 0.113) or the third day (r = -0.034, p = 0.917). CONCLUSIONS: Gutta-percha cones taken directly from manufacturer's sealed package harbored microorganisms. Clinical use of the packages has been found to be associated with additional contamination of the gutta-percha cones. The counts of cultured microorganisms did not correlate well with the number of filled root canals.

Examination of gutta-percha cones for microbial contamination during chemical use.

OBJECTIVE: The aim of this study was to evaluate the degree of microbial contamination in packaged gutta-percha cones before and during use in clinical conditions. MATERIAL AND METHODS: Sealed packages of #15-40 gutta-percha cones were opened under aseptic laboratory conditions. Two gutta-percha cones from each size were randomly drawn and added to tubes containing glass beads and 750 microL of saline. The tubes were vortexed, serially diluted and samples of 250 microL were cultured on agar plates. The plates were incubated at 37 degrees C for 3 days and colonies were counted. The initially sampled packages were distributed to 12 final year dental students. The packages were collected at the end of the first and the third clinical practice days and sampled as described above. RESULTS: Baseline microbial counts did not exceed 3 CFU. At the end of the first and the third day, additional contamination was found in five and three of the packages, respectively. The ratio of contaminated packages at the first day and the third day was not significantly different (z-test; p > 0.05). The numbers of microorganisms cultured at the first day (8 +/- 9.9 CFU) and the third day (4.5 +/- 8.3 CFU) were not significantly different (Wilcoxon signed-rank test; p > 0.05). No significant correlation was found between the number of filled root canals and cultured microorganisms at either the first day (Spearman's rho; r = 0.481, p = 0.113) or the third day (r = -0.034, p = 0.917). CONCLUSIONS: Gutta-percha cones taken directly from manufacturer's sealed package harbored microorganisms. Clinical use of the packages has been found to be associated with additional contamination of the gutta-percha cones. The counts of cultured microorganisms did not correlate well with the number of filled root canals.

Effect of multiple consecutive applications of one-step self-etch adhesive on microtensile bond strength.

AIM: The aim of this study was to evaluate the effects of multiple consecutive coatings of a one-step self-etch adhesive system (Clearfil Tri-S Bond) on the microtensile bond strength (MBS) to dentin. METHODS AND MATERIALS: Nine caries-free human lower third molars were sectioned perpendicular to the long axis to expose the mid-coronal dentin. The teeth were separated into three experimental groups (n=3) according to the number of adhesive resin coats applied. In Group 1 one layer of Clearfil Tri-S Bond was applied according to the manufacturer's instructions. In Group 2 and Group 3 the adhesive was applied in two and three layers, respectively. In these two groups the first layer was applied according to the manufacturer's instructions but the second and third layers of adhesive were not light cured after application. After the placement of the composite, the teeth were sectioned to obtain approximately 1 mm2 beams for testing. Eighteen beams were prepared for each group using the 'non-trimming' method. The MBS values of all specimens were tested, and fracture modes were then determined using a stereomicroscope. RESULTS: The mean MBS values (in MPa) of Group 1 (one coat of the adhesive) was significantly lower (p=0.04) than those of Group 3 (three applied coats of the adhesive). There were no statistically significant differences between Groups 1 and 2 and Groups 2 and 3. CONCLUSION: Within the limitations of this in vitro study the application of multiple coats of a one-step self-etch adhesive may provide an increase in bond strength compared to the application of only one coat of adhesive. CLINICAL SIGNIFICANCE: Three consecutive coats of one-step self-etching adhesive application can improve MBS.

Effect of surface treatments and different adhesives on the hybrid layer thickness of non-carious cervical lesions.

This in vitro study observed and compared the resin and non-carious sclerotic dentin interfaces generated by three different adhesives and two different techniques, using a scanning electron microscope (SEM). Thirty-two human premolars, with buccal, non-carious cervical lesions, were used. The teeth were randomly divided into eight groups. Group 1: Sclerotic dentin was treated with Single Bond (3M). Group 2: After superficial sclerotic dentin was removed with a diamond bur (Diatech, Coltene), the dentin surfaces were treated with Single Bond. Group 3: Sclerotic dentin was treated with Clearfil SE Bond (Kuraray). Group 4: After superficial sclerotic dentin was removed with a diamond bur, Clearfil SE Bond was applied. Group 5: Sclerotic dentin was treated with Xeno III (Dentsply). Group 6: After superficial sclerotic dentin was removed with a bur, Xeno III was applied to the dentin surfaces. For Groups 7 and 8, after the superficial sclerotic dentin was removed with a diamond bur, Clearfil SE Bond, with an additional 37% phosphoric acid gel, was used on the sclerotic dentin surfaces in Group 7 and Xeno III was used in Group 8. In all groups, the cavities were restored with Filtek Supreme (3M). All the specimens were sectioned longitudinally and polished along the cut surface. The sections were treated with 37% orthophosphoric acid for five seconds, rinsed with water and treated with 5% NaOCL for 10 minutes. The specimens were then gold-sputter coated and evaluated under SEM. The thickness of the hybrid layer was measured on the gingival, occlusal and axial dentin interfaces. ANOVA was performed to determine whether there were any statistically significant differences in hybrid layer thickness. Post-hoc multiple comparisons were done with Tukey's test. Hybrid layer thickness was increased with all adhesives when superficial dentin was removed with a bur. Hybrid layer thickness showed significant differences between total-etch and self-etch systems.

The effect of occlusal loading on the microleakage of class V restorations.

OBJECTIVE: This in vitro study evaluated the microleakage of Class V cavities restored with a resin composite and different adhesive systems after occlusal loading. METHODS & MATERIALS: Standardized box-shaped Class V cavities were prepared on the buccal side of 135 non-carious human premolars. The teeth were randomly divided into three groups of 45 premolars each and restored as follows: Group 1-two-step total-etch adhesive (Single Bond, 3M) + resin composite (Supreme, 3M ESPE); Group 2-two-step self-etch adhesive (Clearfil SE, Kuraray) + resin composite and Group 3-one-step self-etch adhesive (Xeno III, Dentsply) + resin composite. The restorations were finished with aluminum oxide discs (Sof-Lex, 3M). Fifteen teeth in each group received 10,000 x 100 N and 250 N occlusal loads, respectively, and the remaining 15 teeth served as the control. The premolars were immersed in 2% methylene blue for 24 hours. The dye penetration was examined under a stereomicroscope, and the results were statistically analyzed by Kruskal Wallis, Mann-Whitney U and Wilcoxon Signed Rank tests to determine differences between the groups. RESULTS: Gingival margins showed more dye penetration than occlusal margins in all the tested groups (p<0.05). In all the tested adhesive systems, 100 N occlusal loading did not change dye penetration; however, Groups 1 and 2 exhibited better marginal sealing than Group 3 at the enamel margins under 250 N occlusal loading. CONCLUSION: Within the limitations of this in vitro study, it may be concluded that enamel margins provided better marginal sealing than dentin/cementum margins and the two-step self-etch adhesive exhibited better marginal sealing than an all-in-one adhesive at the enamel margins under 250 N occlusal loading.

The effect of different finishing and polishing systems on the surface roughness of different composite restorative materials.

AIM: The purpose of this in vitro study was to examine the effect of two different finishing systems on the surface roughness of different types of composite restorative materials. METHODS AND MATERIALS: Thirty specimens, 8 mm in diameter and 3 mm in depth, were prepared using a microfill composite (Clearfil ST, Kuraray Co. Ltd., Osaka, Japan), a hybrid composite (Clearfil AP-X, Kuraray Co. Ltd., Osaka, Japan), and a packable composite (Clearfil Photo Posterior, Kuraray Co. Ltd., Osaka, Japan) cured against a Mylar matrix strip to create a baseline surface. The average surface roughness was measured using a surface profilometer (Surftest 211, Mitutoyo, Japan) in five different positions on each sample before and after finishing with one of the two finishing systems [Sof-Lex discs (3M) and Po-Go (Dentsply)]. The obtained data were analyzed by two-way analysis of variance (ANOVA) at a p=0.05 significance level. RESULTS: There were statistically significant differences in the average surface roughness (Ra, microm) between the Mylar matrix strip, Sof-Lex discs, and Po-Go discs (p<0.05). For all tested materials, the Mylar matrix strip provided smoother surfaces than both of the finishing systems (p<0.05). When the finishing discs were compared, Sof-Lex discs produced a smoother surface than Po-Go discs for all tested materials (p<0.05). CONCLUSION: The Mylar matrix strip provided a smoother surface than Sof-Lex and Po-Go discs. Furthermore, Sof-Lex discs produced smoother surfaces than Po-Go discs. Sof-Lex and Po-Go systems produced clinically acceptable surface roughness for microfill, hybrid, and packable composite resin materials. The effect of finishing and polishing systems on surface roughness was dependent on both the system and the composite resin restorative material.

Mercury exposure in dental practice.

Since elemental mercury is absorbed by dental professionals through direct skin contact or inhalation, the use of mercury in dental amalgam continues to be a controversial issue. In this study, the authors address the possible health risk of occupational exposure to mercury vapor in the dental office. The cytogenetic examination of leukocytes with alkaline comet assay and blood mercury levels with Atomic Absorption Spectrometer of dentists exposed to mercury vapor below 0.1mg/m(3) concentrations failed to find cytogenetic damage and related correlation. However, higher cytogenetic damage and blood mercury levels evaluated in controls from mercury intake by seafood consumption justifies additional study.