Purpose:To compare the effectiveness of phosphoric acid (H3PO4)-pumice compound with conventional hydrochloric acid (HCl)-pumice compound in treating different severities of dental fluorosis with the microabrasion technique.Materials and Methods:Sixty-seven anterior teeth from seven patients with different severities of dental fluorosis were treated. In each patient, half of the teeth were treated with HCl-pumice compound and the other half with H3PO4-pumice compound (split-mouth design). Both treatment compounds were applied for 30-second periods and treatment continued up to 10 minutes. Before and after treatment, standardized photographs were taken. The photographs were compared by two experienced observers unaware of the modality of treatment. Two indices of aesthetics, improvement in appearance (IA) and degree of stain removal (DSR), were determined according to a visual analog scale. The inter- and intra-correlation coefficients were made; then, statistical analyses were calculated using Mann-Whitney and t-test.Results:There were no significant differences in interobserver evaluation. Improvements in aesthetic indices were observed in all fluorotic teeth by both compounds; however, the mean treatment time with HCl-pumice was significantly lower than H3PO4-pumice.Conclusion:The H3PO4-pumice compound improved aesthetic indices in fluorotic teeth similar to the HCl-pumice compound.

Aim:Endodontic treatment generally reduces the fracture resistance of teeth. The purpose of this study was to evaluate the fracture resistance and the mode of fracture of endodontically treated human premolars with different amounts of remaining tooth structure.Materials and Methods:Seventy non-carious human premolars were randomly assigned into 7 groups. Group 1 (ST) did not receive any preparation. The teeth in groups 2-7 received root canal treatment and different preparations. Group 2 (MO-NF): Mesio-occlusal preparation without filling; Group 3 (MOD-NF): Mesio-occluso-distal preparation without filling; Group 4 (MO-F): Mesio-occlusal preparation with direct composite restoration (Z250); Group 5 (MOD-F): Mesio-occluso-distal preparation with direct composite restoration (Z250); Group 6 (CC-D): Mesio-occluso-distal preparation with cusp reduction and direct composite restoration (Z250); Group 7 (CC-InD): Mesio-occluso-distal preparation with cusp reduction and indirect composite restoration (Gradia GC). The fracture resistance (N) was assessed under compressive load in a universal testing machine (Zwick) perpendicular to the occlusal surface at a cross-head speed of 1 mm/min, and the mode of fracture was assessed under stereomicroscope.Statistical analysis:Data was analyzed by Kruskal – Wallis and Mann – Whitney tests and the mode of fracture was analyzed by Chi-square test (P < 0.05).Results:Statistical analysis showed that MO and MOD cavity preparations significantly reduced the fracture resistance of sound teeth. Direct composite restorations can improve the fracture resistance, and Groups 7 and 6 presented the highest fracture resistance values.Conclusions:Teeth with adhesive restorations showed significantly higher fracture resistance values as compared with the non-restored ones.

Introduction: Bioactive glass (BAG) is increasingly used in dentistry, aiming to provide superior mechanical properties, optimal chemical stability, and favorable antimicrobial activity in the oral environment. This study aimed to measure the flexural strength (FS) and antimicrobial activity of resin-modified glass ionomer (RMGI) cement containing 58S nano-BAG. Materials and Methods: In this in vitro study, 0wt (Weight) %, 10wt%, 20wt%, and 30wt% 58S nano-BAG particles were added to RMGI powder in groups 1 to 4, respectively (n=10). Forty specimens were fabricated in metal molds (2 x 25 x 2 mm), and their FS was measured by using a three-point bending test at a crosshead speed of 0.5 mm/min. The antibacterial activity of the materials against Streptococcus mutants was assessed by the disc diffusion test. In addition to the abovementioned experimental groups, one control group (n=10) containing 100% BAG was also considered. Data were analyzed by one-way ANOVA and Tukey’s test. Results: The mean (± standard deviation) FS was 38.71±8.84, 43.61±17.34, 45.62±15.89, and 54.71±14.25 MPa in groups 1 to 4, respectively. No significant difference was noted in FS among the groups (P=0.06). A significant difference was found in the diameter of the growth inhibition zone among the groups (P<0.05), and group 4 containing 30wt% BAG showed minimal bacterial growth. Conclusion: The addition of 10wt%, 20wt% and 30wt% nano-BAG to RMGI powder did not significantly change the FS but the addition of 30wt% nano-BAG to RMGI significantly inhibited the bacterial growth.

Background: To improve the limitations, many modifications in the resin-modified glass ionomer (RMGI) composition have been proposed. In this study, we evaluated the effect of different concentrations of zinc oxide (ZnO) nanoparticles incorporated into RMGI cement on its physical and antimicrobial properties. Materials and Methods: In this in vitro study, ZnO nanoparticles with 0–4 wt.% concentrations were incorporated into RMGI. The following tests were carried out: (a) Antibacterial activity against Streptococcus mutans tested by disc diffusion method, (b) mechanical behavior assessment by measuring flexural strength (FS) and flexural modulus (FM), (c) micro-shear bond strength (μ-SBS), and (d) fluoride and zinc release. Data were analyzed using the statistical tests of ANOVA, t-test, and Tukey's HSD post hoc in SPSS V22. The level of significancy was 0.05. Results: In the disc diffusion method, specimens with 2 wt.% ZnO nanoparticles showed the highest antimicrobial efficacy (P < 0.05). After 1 month of water storage, no significant difference was observed in FS and FM of the samples (P > 0.05). In 2 wt.% ZnO nanoparticles group, μSBS increased in the first 7 days but decreased by 17% after one month, which showed a significant difference with that of the control group. The fluoride release did no change in the ZnO nanoparticle-containing group compared with the control group at all time intervals. Conclusion: Incorporation of 2 wt.% ZnO nanoparticles into the RMGI cement adds antimicrobial activity to the cement without sacrificing FS and fluoride release properties, while decreased μSBS.