Abdul Semih Ozsevik

Color stability and surface roughness of polished anterior restorative materials

The purpose of this study was to investigate the effects of different finishing-polishing techniques on the color stability and surface roughness of various anterior restorative materials after staining. A composite, a compomer, and a resin-modified glass ionomer were used to prepare 120 specimens. Specimens were divided into subgroups: polishing discs, liquid polishing material, aluminium oxidebonded discs, and control. The specimens were stained in a coffee solution. Color parameters (L*a*b*) and surface roughness before and after staining were measured. The color was affected by the material type (p<0.05) and finishing-polishing systems (p<0.05). The composite showed the highest color stability; however, the color differences of all groups were visible even to the nonskilled operator. The Ra values did not significantly change after staining for any of the restorative groups (p>0.05). The finishing-polishing systems had an effect on color after storing in staining solution.

Effect of fibre-reinforced composite on the fracture resistance of endodontically treated teeth

The aim of this study is to evaluate the fracture resistance of root-filled teeth restored with fibre-reinforced composite (everX posterior). Fifty mandibular molars were divided into five groups (n = 10). Group 1: no treatment was applied (intact teeth). Group 2-5: canals were prepared and root filled. Group 2: no coronal restoration was placed. Group 3: teeth were coronally restored with composite. Group 4: composite restorations were performed following polyethylene fibre insertion at the cavity base. Group 5: composite resin placed over everX posterior. After thermocycling (5-55°C, 5000×), fracture resistance was measured. Mean force load for each sample was recorded in Newtons (N). Results were statistically analysed with one-way analysis of variance and post hoc Tukeys tests. The mean force required to fracture samples and standard deviations are as follows: group 1: 2859.5 ± 551.27 N, group 2: 318.97 ± 108.67 N, group 3: 1489.5 ± 505.04 N, group 4: 1958.3 ± 362.94 N, group 5: 2550.7 ± 586.1 N. everX posterior (group 5) was higher than groups 2, 3 and 4 (P < 0.05). There were no significant differences between everX posterior and intact teeth (P > 0.05). Placing fibre-reinforced composite under composite increased the fracture strength of root-filled teeth to the level of intact teeth.

Effect of laser etching on the fracture strength of the monolithic zirconia and fiber-reinforced composite inlay-retained fixed partial dentures

Abstract Aim: The aim of this study was to evaluate the fracture strength of monolithic zirconia and fiber-reinforced composite (FRC) inlay-retained FPDs, both of which are cemented to the laser-etched cavity surfaces. Materials and Methods: Eighty freshly extracted sound human teeth were used. A premolar and a molar tooth were embedded in an autopolymerizing acrylic resin. Forty acrylic resin models were randomly divided into two groups including monolithic zirconia and FRC inlay-retained FPDs (n = 20). Then, these groups were divided into two subgroups according to conditioning of the cavity surfaces with or without Er:YAG laser etching. Monolithic zirconia inlay-retained FPDs were produced by an inLab MC XL milling device using monolithic zirconia blocks. Tescera™ Fiber Reinforcement Materials were used for the FRC inlay-retained FPDs. After 10.000 thermal cycles, fracture strength test was applied to the specimens. Results: The monolithic zirconia inlay-retained FPDs exhibited the highest fracture strength than the FRC inlay-retained FPDs. Fracture strength was increased with laser etching for both restorative materials (p < 0.05). Conclusion: Laser etching had positively effect on the fracture strength of the inlay-retained FDPs.

The combined occluding effect of sodium fluoride varnish and Nd:YAG laser irradiation on dentinal tubules-A CLSM and SEM study.

The purpose of this study is to evaluate the dentinal tubule occlusion potential and penetration of Clinpro® White Varnish (5% sodium fluoride + tri-calcium phosphate) in the presence or absence of Nd:YAG laser. Seventy-five dentin samples collected from 38 freshly extracted human molars were randomly divided into five groups (n = 15). Groups A, B, D, and E were varnished with Clinpro, whereas group C (no treatment) served as the control group. Groups B and E were further irradiated with Nd:YAG laser (1.5 W, 10 Hz, 1 min). All study groups were subjected to pH cycling (kept in 0.3% citric acid 5 min/day for 5 days). Groups A, B, and C were evaluated for tubule occlusion using scanning electron microscopy. Groups D and E were evaluated for penetration with confocal laser scanning microscopy (SEM). Non-parametric Kruskall-Wallis and Dunns statistical tests were used for analysis of SEM results. The penetration depths were analyzed with one-way ANOVA followed by Fishers Least Significant Difference tests. Tubular occlusion of groups A and B were significantly greater than group C (p < 0.05). Tubular occlusion of group B were significantly greater than group A (p < 0.05). Penetration depth for group D was significantly greater than group E (p < 0.05). Laser application improved the tubular occlusion capacity of Clinpro. Contrary, laser reduced the penetration of Clinpro. SCANNING 38:619-624, 2016.

Bond strength of repaired composite resins: surface treatments, adhesive systems, and composite type

Abstract The aim of the present study was to investigate the effects of three different surface treatments and two different adhesives on the microtensile bond strength (μTBS) of repaired composites using the same or different type of resin. Twenty-four nano-hybrid (Ceram X mono-C) and 24 nanofilled (Filtek Ultimate-F) composite discs were prepared. The specimens were aged with 5000 thermocycles and randomly divided into groups according to the surface treatment methods: (a) phosphoric acid (b) Er:YAG laser and (c) aluminum trioxide particle (air abrasion). Fresh composite resins (C and F) were added to the treated surfaces with two different adhesives (two-step and one-step self-etch adhesives). Then, the specimens were aged again. The stick-shaped specimens were prepared from the discs (n = 25) and the sticks were subjected to the μTBS test. Results indicated that significant differences were found in μTBS values among the surface treatment methods. In the C groups, the highest μTBS value (41.3 ± 8.3 MPa) was recorded in the air abrasion and one-step self-etch adhesive group, which were repaired with the same kind of composite. In the F groups, the highest μTBS value was observed in the air abrasion and one-step self-etch adhesive (37.6 ± 12.3 MPa) group. The treatment with air abrasion is more effective than the others, and it may be suggested for composite repair.

The effect of combined use of chitosan and PIPS on push-out bond strength of root canal filling materials

Abstract Adhesion of root canal filling materials to root dentin is important for the long-term success of the treatment. Push-out bond strength test is used to evaluate the adhesion capacity of root canal filling materials to root canal walls. The aim of the present study is to compare the bond strength of root canal filling materials to root dentin after irrigation with EDTA, chitosan and the combination of chitosan and PIPS irridation using push-out bond strength test. Forty-eight extracted teeth were resected until 13-mm long roots were obtained. Root canals were prepared with a size-25 OneShape instrument. Samples were divided into three groups each including 15 roots. Group 1: Canals were rinsed with 0.2% chitosan and subjected to laser irridation with PIPS at the same time. Group 2: Canals were rinsed with 0.2% chitosan. Group 3: Canals were rinsed with EDTA. All canals were filled with .06 tapered gutta-percha and AH-plus sealer. One-mm thick slices were taken from coronal, middle and apical one-thirds of the roots. Push-out bond strength was determined using a Universal Testing Machine. One root from each group was observed under SEM to evaluate the degree of smear removal. Statistical analysis was performed with Kruskall-Wallis test. Results showed that bond strength values were statistically similar in overall evaluation for all groups (p > .05). In segmental evaluation, group 1 revealed the highest bond strength in apical one-third compared to other groups (p < .05).

Effect of coronal cement base and its thickness on the fracture resistance of endodontically treated teeth

Objective: To compare the fracture resistance of endodontically treated teeth with mesiodistocclusal (MOD) cavities restored with only composite resin, 3 mm glass-ionomer cement (GIC) base + composite resin, and 5 mm GIC base + composite resin. Materials and Methods: Fifty extracted intact mandibular molars were randomly divided into five groups each including 10 teeth. Group 1: No cavity preparation or endodontic treatment was applied (intact teeth). Group 2-5: Root canals were prepared with step-back technique and filled lateral condensation of gutta-percha and sealer. Group 2: No coronal restoration was achieved. Group 3: Teeth were coronally restored with only composite resin. Group 4: Coronal restorations were performed with composite resin following 3 mm GIC base placement. Group 5: Composite resin placed over 5 mm GIC base. After finishing and polishing, all specimens were kept in an incubator at 37°C in 100% humidity for 24 h and fracture resistance was tested with a Universal Testing Machine. Mean force load for each sample was recorded in Newtons (N). Results were statistically analyzed with one-way analysis of variance (ANOVA) and post-hoc Tukey′s tests. Results: The mean force required to fracture each sample was as follows: Group 1: 2,745.3; Group 2: 325.9; Group 3: 1,958.1; Group 4: 1,756.3; and Group 5: 1,889.1. Fracture resistance of intact teeth (Group 1) was significantly higher than all other groups. Fracture resistance of teeth in Group 2 (not coronally restored) was significantly lower than all other groups. Fracture resistance values of other three experimental groups (Groups 3, 4, and 5) were not significantly different from each other. Conclusion: Placing a GIC base and its thickness did not significantly affect the fracture resistance compared with composite resin alone.