ABSTRACT
Despite the increasing demand for tooth-colored restorations in dentistry, polymerization shrinkage and marginal microleakage still remains a problem.The purpose of the present study was to evaluate microleakage in three different resin composites, P90, Z250 and Z250 XT, in class V cavity of permanent human premolars.Standardized class V cavities were prepared on the buccal surface of 45 extracted human premolars. The occlusal margins of cavities were prepared at the enamel and gingival margins extending 1mm below the cementoenamel junction. The teeth were randomly assigned into three groups [N=15] and preparations restored with three different composites following the manufacturer instructions: Group A, Filtek Z250 [microhybrid composite] with Adper Single Bond total etch adhesive system; Group B, Filtek Z250 XT [nanohybrid] with Adper Single Bond total etch adhesive system;Group C, Filtek P90 [silorane] with its self-etch adhesive system [P90 system adhesive]. its adhesive system [P90 system adhesive]. The teeth were then subjected to thermal cycles [1000 cycle, 5 degrees and 55 degrees Celsius +/- 2 degrees Celsius] with a dwell time of 30 seconds, and immersed in 2% basic fuchsine for 24 hours. Longitudinally sectioned teeth were examined under the stereomicroscope. Kruskal-Wallis and Mann-Whitney U test at 95% significance level were used.Filtek Z250XT showed significantly higher microleakage than the other two composites [p<0.001]. However, there was no statistically significant difference between P90 and Filtek Z250 [p=0.217].Although all of the restorative systems had microleakage, silorane-based composite showed less microleakage compared to two other methacrylate-based composites
ABSTRACT
Development of new composite resins is one of the most important technological advances in the field of cosmetic dentistry. The aim of this study was to investigate the effectiveness of different light curing units and composite thicknesses on the shear bond strength composite to dentin. In this experimental in-vitro study, the test groups were composed of 80 dentinal samples, prepared on occlusal surfaces of 80 maxillary premolar teeth and routinely divided into 8 groups of 10. Two cylindrical molds [2×2 and 2×5 mm] were filled in bulk using P60 and Ceram X composites and light cured with LED and QTH light curing units .After curing and 3 months aging in 37 degree water, shear bond strength of all samples were obtained using a universal testing machine with 1mm/min crosshead speed. One- and three-way ANOVA were used for statistical analysis using SPSS software. The highest mean of shear bond strength [31.75 MPa] was in group [P60, QTH, 2] and the lowest [15.34 MPa] was recorded in [Ceram X, LED, 5]. Type and thickness of composites had significant effects on the value of shear bond strength and no significant differences were obtained between two light curing units. The shear bond strengths of P60 and CeramX composites tested were much lower when cured in a 5-mm than in a 2-mm increment. The two types of light curing units tested did not show any significant differences in the amount of shear bond strengths
ABSTRACT
Statement of Problem: Although mechanical debridement is considered as the conventional technique in the management of chronic periodontitis, the locally delivered antiseptic agents have also been investigated as an adjunctive therapy
Purpose: The purpose of this study was to investigate the clinical effectiveness of subgingival irrigation with polyvinylpyrrolidone-Iodine [PVP-I] 10%, H[2]O[2] 3%, and the combination of both in the measurement of probing depth and plaque and gingival indices of patients with moderate to severe chronic periodontitis
Materials and Method: In this double-blind randomized clinical trial, 16 patients with moderate to severe periodontitis were selected using the simple random sampling method. They had at least one tooth with a probing depth >/= 5 mm in each quadrant and had undergone phase I of periodontal therapy one month after dental scaling, The initial probing depth, plaque, and gingival indices were recorded and the selected teeth were randomly irrigated with PVP-I 10%, H[2]O[2] 3%, H[2]O[2] 3% + PVP-I 10%, or normal saline. The measurements were repeated five weeks after the procedure. The data were analyzed through running paired-samples t-test, analysis of variance [ANOVA], Wilcoxon Signed Rank Test, and Kruskal-Wallis Test
Results: The mean differences in probing depth before and after subgingival irrigation in patients who were treated with normal saline, H[2]O[2], PVP-I, and PVP + H[2]O[2] were 1.29 mm, 1.35 mm, 1.47 mm, and 1.71 mm, respectively. This indicated a significant difference among all the groups [ p <05]. Furthermore, PVP-I had a positive effect on the gingival index but it had no significant effect on the plaque index
Conclusion: Subgingival irrigation is an effective adjunctive therapy to mechanical debridement in treating moderate to severe chronic periodontitis