Comparison of laser- and bur-prepared class I cavities restored with two different low-shrinkage composite resins: a randomized, controlled 60-month clinical trial.

OBJECTIVE: The aim of this study was to compare the clinical performances of two low-shrinkage composite resins (silorane-based and methacrylate-based) in class I cavities prepared by Er,Cr:YSGG laser or conventional diamond bur over 60 months. MATERIALS AND METHOD: Eighteen patients with four similar-sized occlusal lesions in molar teeth were included to the study. A total of 72 class I cavities were prepared either by Er,Cr:YSGG laser or conventional diamond bur. Cavities were restored with Filtek Silorane (3M-ESPE) (silorane-based) or Kalore (GC) (methacrylate-based) according to the manufacturers' instructions. All restorative procedures were performed by one operator, and the restorations were examined by two evaluators according to the FDI criteria at baseline and at 6, 12, 24, 36, 48, and 60 months. Patients' satisfaction about the preparation methods was also evaluated with a questionnaire. Pearson chi-square test was used for statistical analysis (p = 0.05). RESULTS: The 60-month recall rate was 88.8% and the retention rates for experimental groups were 100%. After 60 months, no significant differences were detected among groups, regarding marginal adaptation, marginal staining, surface staining, color match, and translucency. None of the restorations exhibited postoperative sensitivity or recurrence of caries. CONCLUSION: Different preparation techniques had no effect on the longevity of restorations. The two low-shrinkage composite systems tested were both clinically acceptable after 60 months. CLINICAL RELEVANCE: Low-shrinkage composites showed similar clinical performance in class I cavities prepared with a laser or conventional bur after a 60-month observation period.

Comparison of shear bond strengths of orthodontic brackets bonded with flowable composites.

This study evaluated the shear bond strengths of orthodontic brackets bonded to human premolars using five different combinations of flowable composites and one-step self-etching adhesives (n=12): (1) Adper Easy Bond+Filtek Supreme XT Flow; (2) Futurabond NR+Grandio Flow; (3) Clearfil S3 Bond+Clearfil Majesty Flow; (4) AdheSE One+Tetric EvoFlow; and (5) Transbond Plus Self Etching Primer+Transbond XT Light Cure Adhesive. After shear bond strength testing, adhesive remnant index (ARI) scores were given according to the amount of adhesive and resin remaining on the brackets. On shear bond strength, there were no statistically significant differences between Groups 2 and 4 and between Groups 3 and 5 (p>0.05). On ARI scores, the predominant ARI scores in Groups 1, 2, 3, and 5 were 4, 2, 5, and 4 respectively; in Group 4, they were 0 and 4. Results showed that some combinations of flowable composites and self-etching adhesives might not be suitable for orthodontic use due to their low shear bond strengths and high ARI scores -with the latter signaling the risk of damaging the enamel surface during debonding.

Influence of different conditioning methods on the shear bond strength of novel light-curing nano-ionomer restorative to enamel and dentin.

The purpose of this study was to investigate shear bond strength (SBS) between a light-curing nano-ionomer restorative and enamel or dentin after acid etching, after erbium:yttrium-aluminum-garnet (Er:YAG) laser etching, or after combined treatment. Forty third molars were selected, the crowns were sectioned, and 80 tooth slabs were obtained. The specimens were assigned to two groups, which were divided into four subgroups(n = 10). Group 1 [enamel (e)], treated with 37% phosphoric acid (A) + Ketac nano-primer (K); group 2 [dentin (d)], (A) + (K); group 3(e), Er:YAG laser etching (L) + (A) + (K); group 4(d), (L) + (A) + (K); group 5(e), (L) + (K); group 6(d), (L) + (K); group 7(e), (K); group 8(d), (K). The SBS of the specimens was measured with a universal test machine (1 mm/min). Data were analyzed by independent samples t-test, one-way analysis of variance (ANOVA) and a post-hoc Duncan test (p < 0.05). No difference was determined between groups 3 and 5 (p > 0.05). Group 7 exhibited higher SBS values than those of groups 3 and 5 (p < 0.05). Group 1 showed higher SBSs than those of groups 3, 5 and 7 (p < 0.05). There was no significant difference between groups 4 and 6 (p > 0.05). No difference was observed between groups 2 and 4 (p > 0.05). However, group 2 presented higher SBSs than did group 6 (p < 0.05). Group 8 exhibited the highest SBS values when compared with groups 2, 4 and 6 (p < 0.05). Er:YAG laser adversely affected the adhesion of the light-curing nano-ionomer restorative to both enamel and dentin.

Microleakage and scanning electron microscopy evaluation of all-in-one self-etch adhesives and their respective nanocomposites prepared by erbium:yttrium-aluminum-garnet laser and bur.

The aim of this study was to evaluate the microleakage of all-in-one self-etch adhesives and their respective nanocomposites in class V cavities prepared by erbium:yttrium-aluminum-garnet (Er:YAG) laser and bur. Class V cavities were prepared on both buccal and lingual surfaces of 72 premolars by Er:YAG laser or bur and divided into six groups (n = 24). The occlusal margins were enamel and the cervical margins were cementum. The groups were as follows: group 1 Er:YAG laser preparation (E) + Xeno V (X) + CeramX (C); group 2 bur preparation (B) + X + C; group 3 E + AdheSE One (A) + Tetric EvoCeram (T); group 4 B + A + T; group 5 E + Clearfil S3 Bond (CSB) + Clearfil Majesty Esthetic (CME); group 6 B + CSB + CME. All teeth were stored in distilled water at 37 degrees C for 24 h, then thermocycled 500 times (5-55 degrees C). Ten teeth from each group were chosen for the microleakage investigation and two teeth for the scanning electron microscopy (SEM) evaluation. The teeth that were prepared for the microleakage test were immersed in 0.5% basic fuchsin dye for 24 h. After immersion, the teeth were sectioned and observed under a stereomicroscope for dye penetration. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests (P < 0.05). Bur-prepared cavities presented less microleakage in all groups for enamel (P < 0.05); however, in cervical margins, there were no differences between laser-prepared and bur-prepared cavities in the Xeno V + CeramX and AdheSE One + Tetric EvoCeram groups (P > 0.05). SEM observations of restorative material-dentin interfaces seemed to correspond with those of the microleakage test. Microleakage at the cervical interfaces was greater than that at the occlusal interfaces. Er:YAG laser-prepared class V cavities yielded more microleakage in occlusal margins with all-in-one self-etch adhesives and the respective manufacturer's nanocomposites.

Leakage pathway of different nano-restorative materials in class V cavities prepared by Er:YAG laser and bur preparation.

OBJECTIVE: The aim of this study was to evaluate the microleakage of different nano-restorative materials in Class V cavities prepared by Er:YAG laser and bur preparation. MATERIALS AND METHODS: Class V cavities were prepared on the buccal and lingual surfaces of 72 premolars by Er:YAG laser or bur. The occlusal margins were in enamel and the cervical margins were in cementum. Teeth were randomly assigned to six groups of 12 teeth (n = 24 cavities) each as follows: Group 1, Er:YAG laser preparation (E)+Ketac N100 (K); Group 2, bur preparation (B)+K; Group 3, E+Adper Prompt L-Pop (A)+Filtek Supreme XT Flow (FSF); Group 4, B+A+FSF; Group 5, E+A+Filtek Supreme XT (FS); Group 6, B+A+FS. All teeth were thermocycled 500 times. Ten teeth from each group were chosen for the microleakage investigation and two teeth for the scanning electron microscope evaluation. Teeth prepared for the microleakage test were immersed in 0.5% basic fuchsin dye for 24 h. Afterwards, the teeth were sectioned and observed under a stereomicroscope for dye penetration. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < 0.05). RESULTS: There were significant differences between occlusal and cervical regions for all groups (p < 0.05) except for Group 1. Bur-prepared cavities showed less microleakage in all groups for enamel (p < 0.05); however, in cementum there were no significant differences between the bur- and laser-prepared cavities in nano-glass ionomer and flowable composite groups (p > 0.05). CONCLUSION: It may be concluded that the cavities prepared by Er:YAG laser showed higher degree of microleakage than those conventionally prepared by bur, regardless of the restorative material at enamel margins.

Microleakage of class V cavities with different adhesive systems prepared by a diamond instrument and different parameters of Er:YAG laser irradiation.

OBJECTIVE: The aim of this study was to evaluate the microleakage of composite resin restorations using two different dentine adhesive systems prepared with a diamond instrument and different parameters of Er:YAG laser irradiation. BACKGROUND DATA: Information on this topic with regard to preparing class V cavities with different parameters of Er:YAG laser irradiation and adhesive systems is scarce. MATERIALS AND METHODS: Two hundred class V cavities were assigned to ten groups (n = 20 each): group 1: Er:YAG laser (5 Hz, 600 mJ) + phosphoric acid (PA) + Adper Single Bond 2 (ASB2); group 2: Er:YAG laser (10 Hz, 300 mJ) + PA + ASB2; group 3: Er:YAG laser (15 Hz, 200 mJ) + PA + ASB2; group 4: Er:YAG laser (20 Hz, 150 mJ) + PA + ASB2; group 5: diamond instrument + PA + ASB2; group 6: Er:YAG laser (5 Hz, 600 mJ) + Adper Prompt L-Pop (APLP); group 7: Er:YAG laser (10 Hz, 300 mJ) + APLP; group 8: Er:YAG laser (15 Hz, 200 mJ) + APLP; group 9: Er:YAG laser (20 Hz, 150 mJ) + APLP; and group 10: diamond instrument + APLP. Cavities were restored with a nanofill composite (Filtek Supreme XT Body). After thermocycling, the specimens were stained with 0.5% aqueous basic fuchsin dye and sectioned bucco-lingually. Dye penetration was then scored. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests with Bonferroni correction. The Wilcoxon signed ranks test was used to compare occlusal and gingival scores. RESULTS: Leakage was seen in all groups at both the occlusal and gingival margins. The Kruskal-Wallis test showed statistically significant differences among the 10 groups (p < 0.001). The gingival margins had more microleakage than the occlusal margins (p < 0.001). Pairwise analysis by the Mann-Whitney U test showed that statistically significant differences (p < 0.05) in microleakage were found between groups 3 and 5 (3 > 5), 5 and 7 (7 > 5), and 7 and 8 (7 > 8) at the gingival margin, and between groups 3 and 6 (6 > 3), 3 and 7 (7 > 3), 4 and 6 (6 > 4), and 4 and 7 (7 > 4) at the occlusal margin. CONCLUSION: We concluded that for all groups, microleakage values were higher at the gingival margins. The use of the Er:YAG laser for cavity preparation with different parameters and different dentine adhesive systems influenced the marginal sealing of composite resin restorations.

Comparison of the antibacterial activity of different self-etching primers and adhesives.

AIM: The aim of this study was to evaluate the antibacterial effects of different one-step and two-step self-etching primer/adhesives on Streptococcus mutans (S. mutans), Lactobacillus casei (L. casei), and Lactobacillus acidophilus (L. acidophilus). METHODS AND MATERIALS: The antibacterial effects of Clearfil Protect Bond Primer and Bonding agent; AdheSE Primer and Bonding agent; Adper Prompt L-Pop; Futurabond NR; Clearfil Tri S Bond; and Cervitec (positive control, 1% chlorhexidine varnish) were tested against standard strains of S. mutans, L. Casei, and L. acidophilus using the disk diffusion method. Standard filter paper disks (n=5) impregnated with 20 microL of each material were prepared. After incubation at 37 masculineC for 48 hours in a 5-10% CO2 atmosphere, the diameter of inhibition zones were measured in millimeters. Data were analyzed using one way analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA). Duncan's Multiple Range Test was used for pairwise comparison. RESULTS: The size of inhibition zones produced by primer/adhesives varied among the brands. AdheSE Primer: S. mutans (20.6+/-1.51); L. casei (14.8+/-1.78); L. acidophilus (11.4+/-0.54). Adper Prompt L-Pop: S. mutans (19.6+/-1.51); L. casei (13.8+/-1.64); L. acidophilus (13.8+/-1.09). Cervitec: S. mutans (23+/-0.00); L. casei (27+/-0.70); L. acidophilus (22.4+/-0.54). Clearfil Protect Bond Primer: S. mutans (17+/-0.00); L. casei (17.6+/-0.54); L. acidophilus (22.4+/-0.54). Futurabond NR was found effective only against S. mutans (14.6+/-1.67). Of all the materials tested, AdheSE Bonding agent, Clearfil Protect Bond Bonding agent, and Clearfil Tri S Bond exhibited no inhibition zone (-) for all bacteria tested. CONCLUSION: Among the adhesives tested Clearafil Protect Bond Primer based upon monomer methacryloyloxydodecylpyridiniium bromide (MDPB) was found to be the most potent material against L. acidophilus and L. casei. AdheSE Primer and Adper Prompt L-Pop are highly effective against S. mutans. CLINICAL SIGNIFICANCE: Compared with other adhesive systems, Clearfil Protect Bond Primer (containing MDPB) showed a high antibacterial effect against all microorganizms tested. Two-step, self-etching primer/adhesive system Clearfil Protect Bond might be a suitable choice under minimally invasive restorations. The recently developed one-step, self-etching system Clearfil Tri S Bond showed no antibacterial effect against microorgazims tested.

Influence of location of the gingival margin on the microleakage and internal voids of nanocomposites.

AIM: The aim of this in vitro study was to investigate the cervical microleakage and internal voids of nanocomposites comparing them with a hybrid composite in Class II restorations with the margins located coronal and apical to the cementoenamel junction (CEJ). METHODS AND MATERIALS: Standardized MOD cavities (one cervical margin located in dentin, one in enamel) were prepared in 40 extracted human molars and divided into four groups according to the composite used to restore them (n=10/group). Group 1: Adper Single Bond2/Filtek Supreme XT; Group 2: Excite/Tetric EvoCeram; Group 3: Prime & BondNT/Ceram X; and Group 4 (control) Adper Single Bond2/Filtek Z250. Groups were further divided into subgroups A and B. The "A" subgroups represent the level of the location of the cervial margin at 1 mm coronal to the CEJ, and the "B" subgroups represent the level of the cervical margin located 1 mm apical to the CEJ. After restoration of the cavities with nanocomposites, thermocycling, and immersion in 0.5% basic fuchsin, the dye penetration and internal voids were evaluated under a stereomicroscope. Data were analyzed with the Mann-Whitney U and Kruskal-Wallis tests with the Bonferroni correction for microleakage and with the Chi-square test for internal voids (p<0.05). RESULTS: The microleakage in the A subgroups was statistically significantly lower then B subgroups (p<0.05). No statistically significant difference was observed in terms of interface, cervical, and occlusal voids for all groups (p>0.05). No significant difference was observed between each group for three voids in all groups (p>0.05). CONCLUSION: The location of the gingival margin affects the microleakage of nanocomposites but has no significant affect on the internal voids. CLINICAL SIGNIFICANCE: Gingival margin located 1 mm coronal to the CEJ provided a reduction in cervical microleakage in nanocomposite restorations.

The influence of one-step polishing systems on the surface roughness and microhardness of nanocomposites.

OBJECTIVES: This in vitro study evaluated the surface roughness and microhardness of nanocomposites that contain nanoparticles and a microhybrid composite finished and polished with two different one-step polishing systems and a conventional multi-step polishing system. METHODS AND MATERIALS: The materials evaluated were Filtek Supreme XT, Grandio, Ceram X, Aelite Aesthetic Enamel, Tetric EvoCeram and Filtek Z250. A total of 240 specimens (10-mm in diameter, 2 mm thick) were fabricated for both tests (n=120 each test) in a plexiglass mold covered with a Mylar strip. After polymerization, five specimens per group received no polishing treatment and served as the control for both tests. For each composite group (n=15), the specimens were randomly divided into three polishing systems: PoGo, OptraPol and Sof-Lex. All polishing systems were applied according to the manufacturers' instructions after being ground wet with 1200 grid silicon carbide paper. The surface roughness values were determined using a profilometer. The microhardness measurements were performed using a digital microhardness tester (load 500 g; dwell time 15 seconds). The data were analyzed using the one-way ANOVA test at a significance level of 0.05 for both tests. Multiple comparison was performed with the Duncan Multiple Range test. RESULTS: The smoothest surfaces were achieved under Mylar strips in all composite groups (p<0.05). There were no statistically significant differences between polishing systems in the Filtek Supreme XT, Ceram X, Aelite Aesthetic Enamel and Grandio groups for surface roughness (p>0.05). In the Tetric EvoCeram group, Sof-Lex exhibited the highest roughness values. No statistically significant differences were evaluated between polishing systems (p>0.05); whereas, the surfaces under Mylar Strip showed statistically significant lower values than the polished surfaces in terms of microhardness (p<0.05). CONCLUSION: One-step polishing systems may be successfully used for polishing nanocomposites.

Effect of one-step polishing systems on surface roughness of different flowable restorative materials.

The purpose of this study was to investigate the influence of one-step polishing systems on the surface roughness of different flowable composites and a microhybrid composite. A total of 120 disks were fabricated and divided into six groups according to the different composite restorative materials tested (n = 20). Each group was further divided into four subgroups according to the polishing system (n = 5). For the control group, samples were left undisturbed after removal of Mylar strip. For the other three subgroups, samples were polished with PoGo, OptraPol, or Sof-Lex disks. Surface roughness was determined using a profilometer and observed under scanning electron microscope (SEM). Data were analyzed by one-way ANOVA and Duncan's multiple range test. For Tetric Flow, Grandio Flow, Filtek Supreme XT Flow, and Admira Flow, their lowest surface roughness values were obtained in Mylar Strip and PoGo groups. For Compoglass Flow, there were no significant differences between Mylar Strip, PoGo, and OptraPol. For Filtek Z250, the lowest surface roughness value was obtained with Mylar Strip. In light of the surface roughness results obtained, one-step polishing systems seemed to be a good choice for polishing flowable composites.

The influence of Er:YAG laser conditioning versus self-etching adhesives with acid etching on the shear bond strength of orthodontic brackets.

OBJECTIVE: The aim of this study was to compare the shear bond strength (SBS) of orthodontic brackets after acid etching, laser ablation, self-etching primer application, and combined treatments. METHODS: One hundred defect-free premolars were randomly assigned to five groups. The teeth received the following treatments: group 1: phosphoric acid + Transbond XT primer; group 2: Transbond Plus Self-Etching Primer (TPSEP); group 3: Er:YAG laser ablation + Transbond XT primer; group 4: Er:YAG laser ablation + phosphoric acid + Transbond XT primer; and group 5: Er:YAG laser ablation + TPSEP. Transbond XT Adhesive Paste was used in all groups for bracket bonding. Samples were stored in deionized water at 37 degrees C for 24 h. The shear debonding test was performed at a crosshead speed of 5 mm/min. Failed brackets were examined by a stereomicroscope at 16 x magnification to determine the bond failure interface using a modified adhesive remnant index (ARI). SBS values were compared using one-way analysis of variance (ANOVA). The Kruskal-Wallis test was used for ARI scores and pairwise comparisons were done using the Mann-Whitney U test with Bonferroni correction. RESULTS: Mean SBS values (MPa) and standard deviations for the groups were: group 1, 13.18 +/- 3.45; group 2, 13.52 +/- 4.38; group 3, 10.33 +/- 4.74; group 4, 13.00 +/- 3.47; and group 5, 12.46 +/- 6.31. No significant differences were observed in the SBS of all the groups evaluated, but there was a significant difference in ARI scores, with group 3 showing higher ARI scores than groups 1 and 4. CONCLUSIONS: Er:YAG laser ablation and self-etching primer application showed similar SBS values as conventional acidetching for bonding brackets.

Clinical evaluation of flowable resins in non-carious cervical lesions: two-year results.

This study evaluated the two-year clinical performance of one microhybrid composite and three different types of flowable resin materials in non-carious cervical lesions. A total of 252 noncarious cervical lesions were restored in 37 patients (12 male, 25 female) with Admira Flow, Dyract Flow, Filtek Flow and Filtek Z250, according to manufacturers' instructions. All the restorations were placed by one operator, and two other examiners evaluated the restorations clinically within one week after placement and after 6, 12, 18 and 24 months, using modified USPHS criteria. At the end of 24 months, 172 restorations were evaluated in 26 patients, with a recall rate of 68%. Statistical analysis was completed using the Pearson Chi-square and Fisher-Freeman-Halton tests (p < 0.05). Additionally, survival rates were analyzed with the Kaplan-Meier estimator and the Log-Rank test (p < 0.05). The Log-Rank test indicated statistically significant differences between the survival rates of Dyract Flow/Admira Flow and Dyract Flow/Filtek Z250 (p < 0.05). While there was a statistically significant difference between Dyract Flow and the other materials for color match at 12 and 18 months, no significant difference was observed among all of the materials tested at 24 months. Significant differences were revealed between Filtek Z250 and the other materials for marginal adaptation at 18 and 24 months (p < 0.05). With respect to marginal discoloration, secondary caries, surface texture and anatomic form, no significant differences were found between the resin materials (p > 0.05). It was concluded that different types of resin materials demonstrated acceptable clinical performance in non-carious cervical lesions, except for the retention rates of the Dyract Flow restorations.

Dentin bond strength of composites with self-etching adhesives using LED curing lights.

AIM: The purpose of this study was to investigate the effect of light-emitting diode (LED) light curing units (LCUs) compared with halogen LCUs on the shear bond strength (SBS) of one nanofill composite (Filtek Supreme) and one microhibrid composite (Artemis) with self-etch adhesives. METHODS AND MATERIALS: The buccal surfaces of 60 non-carious extracted human molars were flattened to expose dentin and, subsequently, polished for 60 seconds with 600-grit wet silicon carbide abrasive paper. Specimens were assigned into six groups (n=10) according to composite material, self-etch adhesive, and curing light used as follows: Group 1: Adper Prompt L-Pop (AP) and Filtek Supreme (FS) using an Elipar Free Light (EFL); Group 2: AP and FS using an Elipar Free Light 2 (EFL2); Group 3: AP and FS using a Hilux Expert (HE) light, Group 4: AdheSE (AS)+Artemis (AR) using an EFL; Group 5: AS+AR using an EFL2; and Group 6: AS+AR using a HE light. The specimens were thermocycled for 500 cycles (5 masculineC-55 masculineC) and then loaded to failure in a Zwick universal testing machine at a crosshead speed of 5 mm/minute. SBS values were calculated as megapascals (MPa) and statistically analyzed using the one-way analysis of variance (ANOVA) test at a significance level of 0.05. RESULTS: Mean SBS (+/- standard deviations) values were as follows: Group1: 15.99+/-5.18; Group 2: 18.76+/-6.71; Group 3: 17.70+/-5.04; Group 4: 16.93+/-3.99; Group 5: 18.01+/-5.19, and Group 6: 17.46+/-5.40. There were no statistically significant differences for SBS to dentin among the groups tested. CONCLUSION: The LED curing lights used in the study seem to be comparable with the halogen curing light for nanofill and microhybrid composites used in conjunction with self-etching systems in dentin. The EFL2 reduces curing time, which can be considered as an advantage.

Effect of flowable composite lining on microleakage and internal voids in Class II composite restorations.

PURPOSE: The aim of this study was to determine the influence of four flowable composite linings on marginal microleakage and internal voids in Class II composite restorations with the margins above the cementoenamel junction (CEJ). MATERIALS AND METHODS: Class II cavities were randomly divided into 8 groups (n = 10). Group 1: One Step Plus/Aelite LS Packable; group 2: One Step Plus/Aelite Flow/Aelite LS Packable; group 3: Comfort Bond/Solitaire 2; group 4: Comfort Bond/Flowline/Solitaire 2; group 5: Solobond M/Grandio; group 6: Solobond M/Grandio Flow/Grandio; group 7: Admira Bond/Admira; Group 8: Admira bond/Admira Flow/Admira. After restoration, all teeth were stored for 24 h, thermocycled (at 5 degrees C to 55 degrees C) 500 times, and soaked in 0.5% basic fuchsin dye for 24 h. After soaking, the teeth were sectioned and observed under a stereomicroscope. Gingival marginal microleakage and internal voids (at the gingival wall interface and in the cervical and the occlusal parts) were recorded. Data were analyzed with the Mann-Whitney U- and Kruskal-Wallis tests (p < 0.05). RESULTS: Statistical analyses indicated that the use of flowable resin composites provided a reduction in microleakage in groups 6 and 8. Groups 2 and 4 showed fewer voids in the cervical area than without flowable composites. CONCLUSION: It was concluded that none of the materials tested was able to eliminate the marginal microleakage on the cervical wall. Flowable resin composites under nanohybrid (group 6) and ormocer (group 8) composites provided a significantly different reduction in microleakage compared to restorations without flowable liners. Fewer cervia voids were observed in packable composites with flowable liner (groups 2 and 4) than without flowable liner (groups 1 and 3s).

Shear bond strength of orthodontic brackets bonded using conventional vs one and two step self-etching/adhesive systems.

OBJECTIVE: To assess and compare the effects of one- and two-step self-etching primer and adhesive with conventional acid-etching and bonding system on the shear bond strength of orthodontic brackets. MATERIALS AND METHODS: The one-step self-etching primer and adhesive used was Clearfil tri-S bond, the two-step fluoride-releasing antibacterial self-etching primer and adhesive was Clearfil Protect Bond, and the fluoride-releasing conventional acid-etching and bonding system was Kurasper F Bond. Brackets were bonded to defect-free human premolars (n = 14 per group) according to each manufacturer's recommendations by using light-cured bracket adhesive Kurasper F Paste with a light-emitting diode of a light-curing unit. The specimens were stored in deionized water at 37 degrees C for 48 hours and then tested in shear with a universal testing machine at a crosshead speed of 5 mm/min until the brackets debonded. The mode of failure of the brackets was determined by a modified adhesive remnant index. RESULTS: Mean shear bond strength values were 9.00 MPa for Kurasper F Bond, 9.55 MPa for Clearfil Protect Bond, and 9.48 MPa for Clearfil tri-S Bond. One-way analysis of variance detected no statistically significant difference among groups (P = .98, P > .05). The predominant failure for the three groups was at the bracket-adhesive interface leaving less than 25% of the adhesive on the bracket base. CONCLUSIONS: One-step self-etching adhesive and two-step fluoride-releasing antibacterial self-etching adhesive have sufficient mechanical properties for the bonding of orthodontic brackets.

Effect of two light-emitting diode (LED) and one halogen curing light on the microleakage of Class V flowable composite restorations.

AIM: The disadvantages of light cured composite resin materials with respect to microleakage are predominantly a result of polymerization shrinkage upon curing. It has been shown curing methods play a significant role in polymerization shrinkage of light-cured composite resins. The purpose of this study was to investigate the effect of light-emitting diode (LED) light curing units (LCUs) compared with a halogen LCU on microleakage of three different flowable composites using self-etch adhesives. METHODS AND MATERIALS: A total of 63 extracted human premolars were prepared with standardized Class V cavity preparations on the buccal and lingual surfaces of each tooth. The occlusal margin of the cavities was located on the enamel and the gingival margin was on dentin. Teeth were randomly assigned to three groups of 21 teeth each as follows: Group 1: Adper Prompt L-Pop + Filtek Flow (3M ESPE); Group 2: AdheSE + Tetric Flow (Ivoclar, Vivadent); and Group 3: Clearfil Protect Bond + Clearfil Protect Liner F (Kuraray Medical Inc.). All the groups were subdivided into three groups according to the curing lights used (n=7). Two LED LCUs, Elipar FreeLight and Elipar FreeLight 2 (3M ESPE), and one halogen-based LCU, Hilux Expert (Benlioglu ), were used. All teeth were then immersed in 0.5% basic fuchsin dye solution for 24 hours after thermocycling (500 cycles; between 5 degrees C to 55 degrees C). The teeth then were longitudinally sectioned and observed under a stereomicroscope (40X magnification) by two examiners. The degree of dye penetration was recorded separately for enamel and dentin. Data were analyzed with the Kruskal-Wallis and Mann-Whitney tests with the Bonferroni correction. RESULTS: No statistically significant differences in microleakage were observed between groups either on enamel or dentin (p>0.05). CONCLUSION: With the limitation of this in vitro study, the differences in microleakage between LCUs used were not statistically significantly different. Elipar Free Light 2 reduces curing time which can be considered as an advantage.

The effect of finishing and polishing procedures on the surface roughness of composite resin materials.

AIMS: The aims of this study were to evaluate the effect of various finishing and polishing procedures on the surface roughness of six different composite resin materials (Artemis Enamel, TPH Spectrum, Filtek A-110, Filtek Supreme Enamel, Solitaire 2, and Filtek P-60) as well as to evaluate the effectiveness of the surface sealant application (BisCover) on the surface roughness after finishing and polishing procedures of tested composites. METHODS AND MATERIALS: Specimens (n=168) measuring 5 mm in diameter x 2 mm in thickness were fabricated in a plexiglass well covered with a Mylar strip using six composite resins. A control group of seven specimens of each material received no polishing after being cured under the Mylar strip. Twenty-one specimens for each composite were randomly divided among three finishing and polishing groups (n=7). Each group was polished using a different system: Carbide bur/Sof-Lex disc, Carbide bur/Enhance disc with polishing paste, and Carbide bur/Edenta composite finishing kit. The average surface roughness (Ra, microm) of the control and treated specimens were measured with the Mitutoyo Surftest-402 Surface Roughness tester. After a surface sealant (BisCover) was applied to all treated specimens, according to manufacturer's instructions, the average roughness (Ra) was measured again. Results were statistically analyzed using analysis of variance (ANOVA) and the post-hoc Scheffe's test at a p<0.05 significance level. RESULTS: Significant differences were found for the surface roughness (p<0.05) with interaction among composite resins and the finishing systems used (p<0.05). Enhance/Biscover finishing and polishing procedure surface was not significantly different from the Mylar strip surface groups (p>0.05). The Mylar strip group was not significantly different from the Sof-Lex/BisCover and Edenta/BisCover groups. The ranking of mean Ra values by materials was as follows: Filtek Supreme Enamel < Filtek A110 < TPH Spectrum < Artemis

Radiopacity of direct esthetic restorative materials.

This study determined the radiopacity of 21 commercially available direct esthetic restorative materials with reference to an aluminum step wedge and an equivalent thickness of enamel and dentin. A total of 168 samples measuring 6 mm in diameter and 1 mm in thickness, with eight samples of each material, were prepared from restorative materials. Enamel and dentin samples 1-mm thick were also prepared by longitudinally sectioning eight extracted human permanent molars using a microslicing machine. The optical densities of each restorative material, along with one tooth section and an aluminum step wedge were measured from radiographic images using a transmission photodensitometer. The optical density values of the specimens were used to determine the aluminum thickness equivalent values. The data were analyzed with one-way analysis of variance (ANOVA) and Duncan's multiple range tests. The results showed statistically significant differences among materials. Tetric Ceram had the greatest radiopacity value and was higher than enamel. All materials except for the microfilled resin composite Filtek A 110 had radiopacity values greater than dentin and possessed sufficient radiopacity to meet ISO 4049 standard. Significant differences were found among materials of the same composition when compared to enamel.

Flow, strength, stiffness and radiopacity of flowable resin composites.

OBJECTIVE: This study was undertaken to characterize 9 currently available proprietary flowable composites with respect to key properties of flow, flexural strength, stiffness (modulus of elasticity) and radiopacity. METHODS: Seven proprietary flowable composites (Aelite Flo, Filtek Flow, Heliomolar Flow, PermaFlo, Revolution Formula 2, Tetric Flow, Wave) and 2 flowable compomers (Compoglass Flow, Dyract Flow) were evaluated. A universal hybrid composite (Filtek Z250) and a restorative compomer (Dyract AP) were used as controls. Standard mechanical testing of 25 x 2 x 2 mm bar specimens was carried out at 24 hours and 1 month. Flow testing used a fixed volume of material under consistent loading, and radiopacity was measured simultaneously for all materials using disk specimens of 1 mm thickness. RESULTS: As expected, flowable composites showed higher flow and lower mechanical properties than the controls. Moduli of the composites were approximately 50% or less of the moduli of control materials, which indicates high flexibility. Flexural strengths approached that of the control composite. Flow properties varied widely. The material Tetric Flow had the highest radiopacity, above that of enamel and the control composite. Lowest radiopacity, below or equivalent to that of dentin, was shown by Wave and Revolution Formula 2. CONCLUSIONS: The flowable materials possessed a wide range of mechanical and physical properties. Their lower mechanical properties suggest that they should not be used in bulk in areas of high occlusal loading. Within intracoronal restorations, clinicians are advised to use materials with high radiopacity. A wide range of fluidity options is available. The clinical applications and performance of these materials require further study.

Fluoride release and uptake capacities of fluoride-releasing restorative materials.

Many fluoride-releasing dental materials are being sold on the basis of their cariostatic properties. However, the amount fluoride release of these materials is still uncertain. This study investigated the fluoride release and uptake characteristics of four flowable resin composites (Heliomolar Flow, Tetric Flow, Wave, Perma Flo), one flowable compomer (Dyract flow), one conventional glass ionomer cement mixed with two different powder/liquid ratios (ChemFlex Syringeable and ChemFlex Condensable), one packable resin composite (SureFil), one ion-releasing composite (Ariston pHc) and one resin-modified glass ionomer cement (Vitremer). Seven discs (6-mm diameter and 1.5-mm height) were prepared for each material. Each disc was immersed in 3.5 ml of deionized water within a plastic vial and stored at 37 degrees C. The deionized water was changed every 24 hours and the release of fluoride was measured for 30 days. At the end of this period, the samples were recharged with 2 ml of 1.23% acidulated phosphate fluoride (APF) gel for four minutes. Then, all samples were reassessed for an additional 10 days. The fluoride release of all samples was measured with a specific fluoride electrode and an ionanalyzer. Statistical analyses were conducted using two-way repeated measure ANOVA and Duncan's multiple range tests. For all tested materials, the greatest fluoride release was observed after the first day of the study (p<0.01) but gradually diminished with time. During the test period, Tetric Flow released the lowest amount of fluoride; however, no statistically significant difference was found from Wave and Heliomolar Flow (p>0.05). Ariston pHc released the highest amount of fluoride, followed by ChemFlex Syringeable, Vitremer and ChemFlex Condensable. There were statistically significant differences among these materials (p<0.05). Fluoride release of all materials were significantly increased after the first day following refluoridation and Ariston pHc released the greatest among all materials (p<0.01). At the end of two days of refluoridation, the fluoride release rate for each material dropped quickly and stabilized within three days.