Göknil Ergün Kunt

Objective: The aim of this study was to evaluate the effect of different polishing systems on the colour stability of different laminate veneer blocks for chair-side CAD-CAM after ultraviolet (UV) ageing. Methods: About 240 sample (13 × 13 × 0.7) were prepared from four different CAD-CAM blocks IPS e.max CAD (IP), IPS Empress CAD (IE), Mark II (M) and Lava Ultimate (LU)) with A1 shade. Each group was divided into five subgroups ( n = 12) according to the control (C) and four different polishing system: Sof-Lex (S), Edenta (E), Identoflex (I) and Zircon Brite (Z). Surface roughnesses (Ra) were measured by a profilometer before and after polishing. The baseline colour values were recorded according to the CIELab system. The colour coordinates (L*, a* and b*) of the samples were measured before and after UV ageing, and colour differences (ΔE₀₀) were calculated by using the CIEDE2000 colour difference formula. A two-way ANOVA and Tukey test methods were used to analyse the data (α = 0.05). Results: A significant interaction was observed between CAD-CAM blocks and polishing system ( p < 0.001). The higher Ra and colour difference was calculated in LU in the Z group after polished and the lower Ra and colour difference was calculated in the IP in the S group after polished. For the IP group, the glazing procedure showed higher Ra and ΔE values with Z group than polished S system, whereas there is no statistical differences. Conclusion: It is concluded that polishing with the Sof-Lex system improves significantly smoothness and colour stability. However, there is no success in using the Zircon Brite polishing system.

In the current study, we evaluated the effects of heat treatment (by Er:YAG or furnace) and various surface treatments on the microtensile bond strength (μTBS) of silanized lithium disilicate ceramic. Seventy lithium disilicate (IPS e. max Press; Ivoclar Vivadent) and composite resin (Tetric N-Ceram; Ivoclar Vivadent) blocks were made and distributed into seven groups (n = 10) at random: S: silanization alone; ALS: airborne particle abrasion (APA) and silanization; SC: APA modified with silica and silanization; SHT1: silanization and heat treatment by Er:YAG; SHT2: silanization and heat treatment performed in the furnace (100 °C, 1 min); HF: etching with HF; and HFS: etching with HF and silanization. Every ceramic specimen was cemented to a composite resin block after surface treatment. Cemented specimens were embedded into acrylic resin and were tested with the μTBS test. Data were analyzed using one-way ANOVA and Tamhane T2 tests (α = 0.05). The SHT1 group had the highest bond of strength compared to the other groups (27.46 MPa). The ALS group had the lowest strength of the groups (15.56 MPa). Between SHT2 and HFS (p = 1), the comparison of the mean µTBS values showed no significant differences. It was concluded that silane heat treatment increased the resin composite–ceramic bond strength; however, within the terms of μTBS, the Er:YAG laser treatment was more successful than other surface treatment applications.

Background: Muscle‐related temporomandibular disorders (TMD) may affect the masticatory function. Chewing function can be assessed objectively using bolus‐kneading tests, such as two‐colour chewing‐gum mixing ability test.Objective: The aim was to compare the masticatory function with a two‐colour chewing‐gum test before and after treatment of the masticatory muscle‐related temporomandibular disorder.Methods: Twenty‐one patients with masticatory muscle disorder according to Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) were recruited as an experimental group, and further twenty‐one participants without any TMD were included as controls. Pain intensity (scored on a visual‐analogue scale) and maximum mouth opening (MMO) were recorded. Jaw Functional Limitation Scale‐8 (JFLS‐8) was conducted on all patients. Before and after treatment, masticatory function was evaluated with a validated bolus‐kneading test, using two‐colour chewing gum.Results: There was no statistically significant difference in chewing function before and after treatment in the experimental group (p = .715). When these values were compared with the control group, there were no statistically significant differences (p = .489, p = .890). There was no correlation between masticatory function and VAS, MMO, JFLS‐8 before and after treatment in the experimental group.Conclusion: The two‐colour chewing‐gum test is not sensitive when the masticatory performance is not severely impaired.

Objective: The purpose of this study was to investigate the effect of mouth rinses on the color and translucency of three computer‐aided design and computer‐aided manufacturing (CAD‐CAM) restorative materials in laminate veneer and crown thicknesses.Methods: Specimens from two different 5Y‐TZP zirconia (InCoris TZI (IT), and Zirkonzahn (ZH)) and lithium disilicate (IPS e.max CAD [IC]) in two different thicknesses (0.7 mm for laminate veneer, and 1.5 mm for crown) were sectioned. All specimens were colored with an A2‐shade liquid, and the baseline color values were recorded according to the CIELab system with a spectrophotometer. Each group was divided into two subgroups (n = 15) according to the immersion solution: two different mouth rinses, KL (Klorhex), and LI (Listerine, cool mint) for 180 hours. The color coordinates (L*, a*, b*) of the specimens were measured before and after immersion in a mouth rinse, and TP and ΔE₀₀ color differences were calculated by using the CIEDE2000 color difference formula. A 3‐way ANOVA, Bonferroni test, and 1‐sample t tests were used to analyze the data (α = 0.05).Results: The 3‐way ANOVA revealed a significant interaction of material, thickness, and mouth rinse for translucency parameter and color difference (ΔE₀₀) data (p < 0.001). TP decreased for both zirconia materials in laminate veneer thickness when immersed in LI mouth rinse (p < 0.05). No difference was found among the TP mean values of three materials in crown thickness after immersed in mouth rinses (p > 0.826). Both zirconia materials immersed in LI showed greater discoloration than after immersed in KL (p < 0.05). A significant difference was found in color change values among three materials for the laminate veneer thickness after immersed in LI (p < 0.001). However, all color difference values were within the clinical acceptability threshold, except for when ZH in laminate veneer thickness was immersed in LI.Conclusions: The color change of ZH zirconia with LI mouth rinse in laminate veneer thickness was high. For both zirconia ceramics, translucency decreased and the color was less stable in laminate veneer thickness after immersed in LI compared to the crown thickness.Clinical significance: The results of this in vitro study suggest that long‐term use of alcohol‐containing mouth rinse may alter the optical properties of tested CAD‐CAM materials in tested laminate veneer thickness. For color stability with the long term use of tested mouth rinses, lithium disilicate may be preferred for both types of restorations.

The aim of this study was to analyze the surface roughness of yttrium stabilized tetragonal polycrystalline zirconia (Y-TZP) ceramics after different laser treatments (CO_2, ER: YAG). 5x5x2 mm rectangular prisms of forty eight Y-TZP (Zirkonzahn) ceramic specimens were prepared. In order to standardize surfaces, 600-, 1200- grid silicon carbide papers were used to gradually ground wet on 300 rpm grinding machine for 10 s. Eight groups (n = 6) were randomly formed from the specimens of each ceramic as control (GroupC), sandblasted (GroupS), two different CO₂ laser treatments (Group3W: 3 W and 382 w/cal, Group4W: 4 W and 509w/cal) and four different Er: YAG laser treatments (Group150SP: 150 mJ and 10-Hz with 100μS; Group150SSP: 150 mJ and 10-Hz with 300μS; Group300SP: 300 mJ and 10-Hz with 100μS; Group300SSP: 300 mJ and 10-Hz with 300μS). A profilometer was used to conduct surface roughness measurements (Ra). Surface morphologies of the specimens were evaluated under SEM after laser treatment. To analyze the data one-way ANOVA and to compare the mean values Tukey HSD tests (α = .05) were used. One - way ANOVA results showed that Group S had the highest Ra value and Group150 SP had the lowest. After sandblasting group the highest value was seen in Group4W. There were no statistically significant differences among Group C, Group3W, Group150SSP, Group300SP, and Group300SSP. The study showed that surface roughness of zirconium oxide ceramics was increased with CO2 laser.

Introduction. This study examined the antioxidant treatment on the shear bond strength of composite resin to enamel after bleaching with two different bleaching systems. Materials and methods. Seventy flat enamel surfaces were prepared from freshly extracted human molars using a low speed diamond saw. Then the specimens were divided into seven random groups (n = 10) to apply different procedures; namely, bleaching with White Smile and bonding with composite resin (G1), bleaching with White Smile, treatment with ascorbic acid and bonding with composite resin (G2), bleaching with White Smile, immersing in artificial saliva for 2 weeks and bonding with composite resin (G3), bleaching with Opalesence and bonding with composite resin (G4), bleaching with Opalesence, treatment with ascorbic acid and bonding with composite resin (G5) and bleaching with Opalesence, immersing in artificial saliva for 2 weeks and bonding with composite resin (G6). Another group was used as a control group. Shear bond test was performed on all specimens and data were analyzed using one way ANOVA and Bonferroni's test (p < 0.05). Results. Bond strengths of bleached specimens were significantly lower than those of non-bleached specimens. No statistical difference was found in bond strength between the bleached and non-bleached groups when the antioxidant treatment was carried out. Conclusion. Ten per cent ascorbic acid treatment was found to be an effective method to reverse the compromised bond strength.