Evaluation of effect of different disposable infection control barriers on light intensity of light-curing unit and microhardness of composite - An in vitro study.

AIMS: This study evaluated effect of infection control barriers on light intensity (LI) of light-curing unit (LCU) and microhardness of composite. MATERIALS AND METHODS: Four different disposable barriers (n = 30) were tested against the control. LI for each barrier was measured with Lux meter. One hundred and fifty Teflon molds were equally divided into five groups of thirty each. Composite was filled in bulk in these molds and cured without and with barrier. Microhardness was evaluated on top and bottom surface of composite specimen with microhardness testing machine and hardness ratio (HR) was derived. STATISTICAL ANALYSIS USED: One-way analysis of variance, Tukey's honestly significant difference test, and paired t-test using SPSS version 18 software. RESULTS: All barriers had significantly reduced the baseline LI of LCU (P < 0.0001), but only Cure Elastic Steri-Shield and latex cut glove pieces (LCGP) significantly reduced the microhardness of the composite (P < 0.05). However, HR determined inadequate curing only with LCGP. CONCLUSIONS: Although entire tested barrier significantly reduced the LI; none, except LCGP markedly affected the degree of cure of the composite.

Comparative evaluation of shaping ability of V-Taper 2H, ProTaper Next, and HyFlex CM in curved canals using cone-beam computed tomography: An in vitro Study.

AIM: The aim of this study was to compare the canal transportation and canal centering ability in the preparation of curved root canals after instrumentation with V-Taper 2H, ProTaper Next (PN), and Hyflex CM files using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Thirty mesiobuccal canals of mandibular molars with an angle of curvature ranging from 20 to 40 were divided according to the instrument used in canal preparation into three groups of ten samples each: V-Taper 2H (Group 1), PN (Group 2), and Hyflex CM (Group 3). The teeth were instrumented according to manufacturer's guidelines up to 30 no. apical preparation. Canals were scanned using a CBCT scanner before and after preparation to evaluate the transportation and centering ratio at 3 mm, 6 mm, and 9 mm from the apex. The amount of transportation and centering ability was assessed. The three groups were statistically compared with analysis of variance and post hoc Tukey test. RESULTS: All instruments maintained the original canal curvature with significant differences between the different files. Data suggested that V-Taper 2H files presented the best outcomes for both the variables evaluated. V-Taper 2H files caused lesser transportation and remained better centered in the canal than PN and Hyflex CM files. However, it was seen that PN caused less transportation in apical level than Hyflex CM. CONCLUSION: The canal preparation with V-Taper 2H showed lesser transportation and better centering ability than PN and Hyflex CM.

Mouthrinses affect color stability of composite.

AIM: The aim of this study is to evaluate the effect of alcohol and nonalcohol containing mouth rinses on the color stability of a nanofilled resin composite restorative material. MATERIALS AND METHODS: A total of 120 samples of a nanofilled resin composite material (Tetric N-Ceram, Ivoclar Vivadent AG, FL-9494 Schaan/Liechtenstein) were prepared and immersed in distilled water for 24 h. Baseline color values were recorded using Color Spectrophotometer 3600d (Konica Minolta, Japan). Samples were then randomly distributed into six groups: Group I - distilled water (control group), Group II - Listerine, Group III - Eludril, Group IV - Phosflur, Group V - Amflor, and Group VI - Rexidin. The postimmersion color values of the samples were then recorded, respectively. RESULTS: Significant reduction in the mean color value (before and after immersion) was observed in nonalcohol containing mouth rinses (P < 0.001). CONCLUSION: All mouthrinses tested in the present in-vitro study caused a color shift in the nanofilled resin composite restorative material, but the color shift was dependent on the material and the mouthrinse used. Group VI (Rexidin) showed maximum color change.

Stereomicroscopic evaluation of dentinal defects induced by new rotary system: "ProTaper NEXT".

INTRODUCTION: The objective of this study was to evaluate dentinal defects formed by new rotary system - Protaper next™ (PTN). MATERIALS AND METHODS: Sixty single-rooted premolars were selected. All specimens were decoronated and divided into four groups, each group having 15 specimens. Group I specimens were prepared by Hand K-files (Mani), Group II with ProTaper Universal (PT; Dentsply Maillefer), Group III with Hero Shaper (HS; Micro-Mega, Besancon, France), and Group IV with PTN (Dentsply Maillefer). Roots of each specimen were sectioned at 3, 6, and 9mm from the apex and were then viewed under a stereomicroscope to evaluate presence or absence of dentinal defects. RESULTS: In roots prepared with hand files (HFs) showed lowest percentage of dentinal defects (6.7%); whereas in roots prepared with PT, HS, and PTN it was 40, 66.7, and 26.7%, respectively. There was significant difference between the HS group and the PTN group (P < 0.05). CONCLUSION: All rotary files induced defects in root dentin, whereas the hand instruments induced minimal defects.

Evaluation of softening ability of Xylene & Endosolv-R on three different epoxy resin based sealers within 1 to 2 minutes - an in vitro study.

OBJECTIVES: This study evaluated the efficacy of Endosolv-R and Xylene in softening epoxy resin based sealer after 1 to 2 min exposure. MATERIALS AND METHODS: Sixty Teflon molds (6 mm × 1.5 mm in inner diameter and depth) were equally divided into 3 groups of 20 each. AH 26 (Dentsply/De Trey), AH Plus (Dentsply/De Trey), Adseal (Meta-Biomed) were manipulated and placed in the molds allotted to each group and allowed to set at 37℃ in 100% humidity for 2 wk. Each group was further divided into 2 subgroups according to the solvents used, i.e. Xylene (Lobachemie) and Endosolv-R (Septodont). Specimens in each subgroup were exposed to respective solvents for 1 and 2 min and the corresponding Vicker's microhardness (HV) was assessed. Data was analysed by Mauchly's test and two-way analysis of variance (ANOVA) with repeated measures, and one-way ANOVA. RESULTS: Initial hardness was significantly different among the three sealers with AH Plus having the greatest and Adseal having the least. After 2 min, Xylene softened AH Plus and Adseal sealer to 11% and 25% of their initial microhardness, respectively (p < 0.001), whereas AH 26 was least affected, maintaining 89.4% of its initial microhardness. After 2 min, Endosolv-R softened AH 26, AH Plus and Adseal to 12.7, 5.6 and 8.1% of their initial microhardness, respectively (p < 0.001). CONCLUSIONS: Endosolv-R was a significantly more effective short term softener for all the tested sealers after 2 min whereas Xylene was an effective short term softener against AH plus and Adseal but less effective against AH 26.