European Oral Research最新文献

Purpose: The aim of this in-vitro study was to evaluate the effect of thermal changes to shear bond strength during the firing process of veneering porcelain on a zirconia framework.

Materials and methods: Single yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) framework ceramic (Kavo Dental GmbH) and three different types of veneering ceramics (IPS e.max Ceram, Vita VM9, and GC Initial Zr-FS) were used. One-hundred-twenty standard disc-shaped samples were prepared from zirconia blocks by using a CAD/CAM system (Kavo Everest). Four different cooling processes (maximum, 25°C/min, 50°C/min and 75°C/min) were applied to the veneering ceramics and the shear bond strength (SBS) test was performed. Ceramic surfaces were investigated by using scanning electron microscopeic (SEM). The possible occurrence of a t-m transformation of zirconia was evaluated by X-Ray Diffraction (XRD). Two-way analysis of variance, Bonferroni correction and paired comparisons were used for statistical analysis.

Results: The main effects of veneering ceramics on shear bond strength were found to be significant (p=0.042). The mean shear bond strength values differ according to the cooling process (p<0.001). The monoclinic phase ratio increased in groups with fast cooling process.

Conclusion: The thermal changes during the firing process of veneering porcelain on a zirconia framework influenced the shear bond strength of the all-ceramic bilayered system. A slow cooling process provided higher strength for bilayer ceramic samples.

Purpose: The popularity of dental amalgam arises from its excellent long-term performance, ease of use, and low cost. However, there is a concern about the potential adverse health effects arising from exposure to mercury in amalgam. This review article critically discusses the safety of dental amalgam as a restorative material and our preparedness for a mercury-free road ahead.

Materials and methods: A database search was performed on PubMed and Google scholar using the keywords: "mercury-free dentistry", "mercury toxicity", "amalgam substitutes", "amalgam mercury toxicity". Inclusion and exclusion criteria were specified clearly. Relevant literature was also searched in the dental textbooks.

Results: Around 40 articles, highlighting mercury exposure among dental professionals and patients were included. Despite the overwhelming body of scientific evidence demonstrating amalgam to be a safe restorative material, concerns about the toxic effects of mercury persist.

Conclusion: The real challenge is to find a suitable amalgam substitute and to follow the mercury hygiene measures closely.

Purpose: This study aimed to assess the effectiveness of ultrasonic denture hygiene interventions in improving denture cleanliness among elderly individuals.

Materials and methods: Sixty-six participants who had received upper metal framework removable partial dentures within the past 5 years were randomly allocated into three denture hygiene intervention groups: group 1 (mechanical cleaning with a toothbrush and ultrasonic cleaning with cetylpyridinium chloride), group 2 (mechanical cleaning with a toothbrush and ultrasonic cleaning with distilled water), and control (mechanical cleaning with a toothbrush only). Denture cleanliness was assessed at baseline and 1-month using: i) Denture Cleanliness Index (DCI) scores; ii) plaque coverage percentage; and (iii) microbiological samples for bacterial and yeast detection. Differences between groups were assessed with one-way analysis of variance and Chi-squared tests.

Results: Mean DCI scores and mean percentages of plaque coverage area were significantly reduced in group 1 and group 2, compared to the control group for both cobalt chromium (CoCr) and acrylic fitting surfaces (p<0.001). No significant differences were found between groups 1 and 2 with regard to the prevalence and viable counts of yeasts or total microbial viable counts. No significant differences in the investigated clinical and microbiological parameters were observed between CoCr and acrylic surfaces following the intervention period.

Conclusion: The ultrasonic cleaner was significantly more effective than mechanical cleaning in the reduction of biofilm coverage on metal framework removable partial dentures over a 1-month intervention period. Nevertheless, the adjunctive use of cetylpyridinium chloride with ultrasonic cleaning did not yield additional benefits.

Purpose: The present study aims to assess the effect of sports on the dental maturity using two different dental age assessment methods and to determine whether there is a significant correlation between dental maturity and body mass index.

Materials and methods: One hundred and thirty-eight students from Sports High School (study group) and 126 from Fine Arts High School (control group) with standard panoramic radiographs were included in the study. Dental age was assessed using Nolla's and Haavikko's methods. Demographic information regarding the weekly training hours and sports age of the study group participants was gathered. Body mass index values of all participants were calculated. Factorial analysis of variance and Tukey's test were performed and the Pearson correlation coefficient was calculated.

Results: The mean age of the students was 15.93 ± 1.13 years for the study group and 15.99 ± 1.09 years for the control group. Mean dental age values were lower than the mean chronological age values in both high schools. The difference between the dental and chronological ages was insignificant in Sports High School (p > 0.05). Differences in the body mass index between high schools and genders were statistically significant (p<0.05). Significant correlations were detected between the sports and dental ages and between dental age and body mass index values.

Conclusion: Sports participation could have positive effects on the dental maturity as well as on the bone development.

Purpose: This study aimed to examine the effect of beverages at different temperatures on the coloring of composites.

Materials and methods: A total of 48 cylindrical samples, 24 of which were prepared from 2 composite materials (G'aenial; Estelite Σ Quick), were included in the study. The sample dimensions were standardized at 2 x 10 mm2. After the polishing, the initial color measurements were performed using a spectrophotometer. The samples were divided into 3 subgroups as distilled water, hot coffee (60 °C) and cold coffee (0 °C) (n=8). During the 7th and 30th days, the samples were immersed in the solutions for 15 min every day. Color measurements were repeated on the 7th and 30th days. Data were analyzed using a two-way analysis of variance, followed by the Tukey post-hoc test (p<0.05).

Results: The highest color change was detected on the 7th and 30th days in the G-aenial anterior microhybrid composite immersed in hot coffee (p<0.001). The application of hot and cold coffee applications did not make a statistically significant difference in the coloration of the Estelite Σ Quick composite samples at the end of the 7th (p=0.346) and 30th (p=910) days.

Conclusion: Hot drinks had a more coloring effect on restorations. This coloration was quite evident in the microhybrid composite.

Purpose: To evaluate and compare shear bond strength (SBS) of new and recycled metallic brackets bonded to conditioned and reconditioned enamel, using two different adhesive materials.

Materials and methods: 72 extracted sound human premolars were randomly divided into 6 groups. Transbond XT light cured composite (LCC) and Fuji Ortho LC resin-modified glass ionomer (RMGI), were used as adhesive materials. In groups 1 and 2 (control), new brackets were bonded to sound premolars using either LCC or RMGI, respectively. In Groups 3 and 4, new brackets were bonded to reconditioned enamel; and in groups 5 and 6, sandblasted recycled brackets were rebonded to reconditioned enamel. After 5.000 thermal cycles between 5ºC and 55ºC, SBS was evaluated and adhesive remnant on the enamel assessed using the ARI index. Statistical analyses included Shapiro-Wilk, ANOVA, Fligner-Killeen ANOVA and Tukey tests.

Results: The statistical analysis showed no significant difference in SBS comparing control and experimental groups for either new or recycled brackets (p = 0.848). The SBS was significantly higher in brackets bonded with LCC (15.7 MPa) than RMGI (11.6 MPa) (p = 0.006). Adhesive failure was the most frequent, with the adhesive remnant covering more than 50% of the bracket base.

Conclusion: No significant differences were observed in SBS using either new or recycled brackets, regardless of the dental surface treatment (conditioned or reconditioned). Significantly higher SBS values were obtained with LCC adhesive. Adhesive failure prevails in all groups.