Duygu Kürklü

The effect of staining solutions on the color stability of provisional prosthodontic materials

OBJECTIVES The aim of this study was to evaluate the effects of staining solutions on the color stability of self-cure provisional resin materials. METHODS The specimens were prepared for each of three auto-polymerized bis-acryl resin and auto-polymerized methyl methacrylate provisional resin material. The baseline color values were measured with a colorimeter according to the CIE L(*)a(*)b(*) color scale. After the first measurement (T(0)), specimens were placed in staining solutions (coffee, coca-cola, burn and distilled water for control group) and the other measurements were taken after 24h (T(1)), 1 week (T(2)) and 4 weeks (T(3)). RESULTS Data were analyze statistically by (a) repeated measures (ANOVA), (b) one and two way ANOVA, and (c) Tukey HSD multiple comparison tests. At the 24h immersion period, the post hoc analysis indicated that AccessCrown-coffee revealed the highest ΔE(*) values (4.4). At the second immersion period (1 week), Structur2 SC-coffee had the highest ΔE(*) values compared with other materials (5.4). CONCLUSIONS The degrees of discoloration were increased with immersion time. The methylmethacrylate resin was more resistant to discoloration than bis-acryl resins. After immersion for 30 days, the coffee solution resulted in unacceptable discoloration for all the tested materials.

Influence of different surface treatments on push-out bond strengths of fiber-reinforced posts luted with dual-cure resin cement

OBJECTIVES The objective was to evaluate whether fiber postsurface conditioning with air abrasion or erbium:yttrium-aluminum-garnet (Er:YAG) laser would influence the bond strength of dual-cure resin cement to the fiber-reinforced (FRC) posts. MATERIALS AND METHODS Twenty-one FRC posts were divided into three groups according to surface treatment methods as follows: An untreated control group air abrasion with Al2O3group, and Er:YAG laser treated group with 150 mJ parameter. Fiber posts were then built up to dual-cure resin cement. Eighteen specimens were set and sectioned perpendicularly along the long axis of the post using a saw. Two disks (thickness of 2 mm) were obtained from each specimen (n = 12). Remaining three posts were stored for scanning electron microscopic evaluation. Push out test was performed on the each specimen and the values were recorded as MPa. The data were analyzed using one-way analysis of variance and Tukey post-hoc tests (P < 0.05). RESULTS The bond strength values for the groups were as follows: Control (15, 28 MPa), air abrasion group (19, 73 MPa), and Er:YAG group (17, 84 MPa). Air abrasion affected the bond strength significantly (P < 0.05). CONCLUSION Air abrasion attained higher bond strengths when FRC posts were luted to dual-cure resin cement. Additional studies should be designed with different types and parameters of laser devices to understand the effect of these devices on bond strength.

The Evaluation of Flexural Strength of Composite Resin Materials with and without Fiber

The aim of the present study was to evaluate the effect of solutions, times of storage and reinforcement with fiber on the flexural strength of different composite materials. Nanofill and nanohybrid composite materials with and without fiber, a glass fiber and polyethylene fiber, were tested in the present study. 72 specimens (25×2×2 mm³) were prepared as following six groups; Group ECME: everStick Fibre / Clearfil Majesty Esthetics, Group EFU: ever Stick Fibre / Filtek Ultimate, Group RCME: Ribbond Fibre / Clearfil Majesty Esthetics, Group RFU: Ribbond Fibre / Filtek Ultimate, Group CME: Clearfil Majesty Esthetics, Group FU: Filtek Ultimate. The specimens were stored in distilled water and mouthwash and tested after 24 hours and 7 days. Data were analyzed using analysis of variance and Schefee test. It was found that the EFU group in distilled water for 24 hours had the highest flexural strength and the CME group in mouthwash for 7 days had the lowest flexural strength. The storage times and the solutions were not statistically significant factors affecting on the flexural strength. The mean flexural strength values of the RCME and the RFU groups were similar to the FU group.

SEM evaluation of surface morphologic analysis of restorative materials with three laser treatment

Objective: The aim of this study is to analyze the effect of laser treatment on surface morphology of restorative materials. Materials and Methods: The samples included 19 porcelain ceramics (Group P), 10 half yttrium stabilized zirconia (Y-TZP) and half porcelain (Group ZP), and 13 Y-TZP ceramic (Group Z). Pilot study was applied on the prepared samples to determine the effectiveness of hydroxyapatite or graphite powder before surface treatment. Following the pilot study, three laser systems were treated over all ceramic surfaces and scanning electron microscope (SEM) images were taken to do topographic analysis of the samples. Results: According to the results of pilot study; surfaces of zirconia, porcelain, and zirconia-porcelain samples were covered with graphite powder and then treated by CO 2 laser, erbium:Yttrium-aluminum-garnet (Er:YAG) and neodymium:YAG (Nd:YAG) laser. SEM observations were reported for all laser types and all laser parameters that were chosen. Conclusion: The three types of laser products; CO 2 , Er:YAG, and Nd:YAG are also effective on different output powers on different types of restorative materials.

Effects of tongue movements on lingual sulcus depth while border molding in mandibular complete dentures.

BACKGROUND In general, people speak and swallow frequently in their daily lives rather than making exaggerated tongue movements. AIM The aim was to compare the effect of tongue movements on lingual sulcus depth, during the border molding process of impression making of mandibular complete dentures. SETTINGS AND DESIGN In total, 32 double master impressions were made. One of these pairs was obtained by allowing the patient to swallow and the other by enabling the tongue to make excessive movements. MATERIALS AND METHODS Measurements were taken from different regions of the lingual sulcus by determining the length of the parallel lines drawn from fixed points marked on the residual ridge crest to the deepest point of the alveolingual sulcus. These measurements were performed using a RMI three-dimensional measurement system. STATISTICAL ANALYSIS USED Data were compared using the paired t-test (alpha = 0.05). RESULTS AND CONCLUSION The high value found in casts with border molding, while swallowing was statistically significant in vertical and horizontal directions of the anterior lingual sulcus region (<0.001), vertical direction of the middle lingual sulcus region (MLSR) (<0.05) and horizontal direction of the retromylohyoid and MLSR (<0.05). According to the paired t-test, the mean differences between the 32 casts were statistically significant (<0.001). Within the limitations of this study, the swallowing in the vertical and horizontal directions provided higher values compared to the excessive movement of the tongue.