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Öğe Effect of Disposable Sheaths on the Vickers Microhardness of Resin Composites(Marmara Univ, Inst Health Sciences, 2021) Atay, Meltem Tekbas; Dindar, Mediha Buyukgoze; Ozveren, NeslihanObjective: The aim of this study was to evaluate the effect of disposable sheaths on microhardness of resin composites. Methods: A total of 40 resin composite specimens were fabricated with disc-shaped perspex molds (5x2 mm). Specimens were divided into 4 groups: Irradiated by 1-Elipar LCU (EL), 2-Elipar LCU with sheath (ELS), 3-Valo LCU (VL), 4-Valo LCU with sheath (VLS), (n=10). The specimens were subjected to surface microhardness (SMH) test (Tronic, Digital Microhardness Tester DHV-1000) on the top and bottom surfaces under 200 g load applied for 10 s with a Vickers indenter. The specimens were stored in the distilled water at 37 degrees C for 24 hours and the same measurements were repeated. One-way ANOVA test, Tukey and Tamhane post-hoc tests were used for intergroup comparisons. Also paired sample t-test was used for comparisons of the different time results. Results: According to the 1st-hour data from the top and bottom SMH measurements, EL and VL groups have significantly higher microhardness values than VLS and ELS groups (p<0.05). There was a dependent change in the top surface measurements with the time (p=0.000), but also interaction with the LCU (p=0.000). All groups showed significant microhardness decrease from 1st to 24th-hour for both top and bottom values (p<0.05) except for top SMH of VLS group (p=0.151). Conclusion: Disposable sheaths decreased the light output of the LCU's and caused reduction in the SMH. Although they are effective in preventing cross-infection, they significantly reduced the polymerization efficiency, thereby mechanical properties of resin composites.Öğe The effect of toothbrush abrasion on wear and surface roughness of direct and indirect composite laminate veneer restorations(Iop Publishing Ltd, 2020) Dindar, Mediha Buyukgoze; Atay, Meltem TekbasDirect and indirect composite laminate veneers have been frequently used, however the wear of composite restorative materials is still a major problem. Objective: This study aimed to investigate the surface roughness and wear of composite laminate veneers made by two different methods after toothbrushing simulation. Material and Methods: Ninety-six upper incisors and canines were divided into two groups: 1-Componeer prefabricated composite veneer (CPV), 2- Uveneer direct composite veneer (UDV). At the UDV group, restorations were made by using Uveneer template system with the same nanofilled composite material (Synergy D6, Coltene, Altstatten, Switzerland) of the prefabricated Componeers'. The initial surface roughness was measured with a profilometer, then the weight was measured. Before the simulation, samples were screened with a 3D extra-oral scanner. Toothbrush simulation was performed at 10,000 rotational strokes with 2.5 N. The measurements were repeated after toothbrushing simulation. Data were analyzed using variance analyses and t-tests (p < 0.05). Results: Before and after polishing, a significant difference was found between two groups' surface roughness in both lateral incisors (p = 0.000, p = 0.000) and canines (p = 0.048, p = 0.001), respectively. After toothbrushing simulation, significant increases were observed in central and lateral incisors' surface roughness with two methods. There was no significant difference between weight loss (p > 0.05). In 3D scans, wear rate was quite similar except UDV group central incisors. Conclusions: Surface roughness of the CPV restorations were less affected after toothbrushing simulation. However, the Uveneer template system, a facilitated treatment procedure compared to the manual buildup of direct restoration, has shown comparable results with CPV's.Öğe Radiographic Evaluation of Marginal Bone Height and Density Around Overhanging Dental Restorations(Quintessence Publishing Co Inc, 2022) Dindar, Mediha Buyukgoze; Acikgoz-Alparslan, Ece; Tekbas-Atay, MeltemThis study aimed to investigate the marginal bone changes beneath overhanging restorations. The study group consisted of 250 archived panoramic radiographs that had at least one overhanging restoration, examined by two observers. The distance from the cementoenamel junction (CEJ) to the marginal bone crest beneath the overhang was measured with lmageJ software. The same distance was measured from the control sites (the intact surface of the same tooth with overhang, and the same tooth on the contralateral side) to assess bone loss. To evaluate bone density, two regions of interest (ROls) were chosen: one in the marginal bone beneath the overhang, and the other was in the marginal bone adjacent to the intact surface of the same tooth. Wilcoxon paired t test and Mann-Whitney U test were used for comparisons (P < .05). The prevalence of overhangs was 4.3%. Molar teeth (80.8%) and the disto-ocdusal cavities (54%) were the most common sites for overhangs. The average bone loss beneath the overhangs was 2.77 +/- 1.20 mm, which was significantly different from the control sites (P < .05). The bone density beneath the overhang was significantly lower than at control sites (P < .05). The frequency of overhangs was higher in areas that are difficult to reach, and the height and density of the marginal bone beneath the overhang were decreased compared to control sites.Öğe Spatial-temporal variability and probabilistic health risk assessment of fluoride from lentic ecosystem, Turkiye(Taylor & Francis Ltd, 2023) Tokatli, Cem; Onur, Sirin Guner; Dindar, Mediha Buyukgoze; Malafaia, Guilherme; Islam, Abu Reza Md Towfiqul; Muhammad, SaidThrace Region is a part of the Marmara Region of Turkiye. There are many natural and artificial stagnant water habitats in the region that are used for irrigation and drinking water supply. This study is intended to determine the spatial-temporal variability and probabilistic health risk of fluoride exposure in the water of stagnant water bodies in the Thrace region. A total of 33 stagnant water bodies were selected, and water samples were collected during the dry and wet seasons of 2021-2022. The fluoride levels were measured using a spectrophotometric method (wavelength is 588 nm). The fluoride accumulations varied from 0.16-0.64 mg/L for the natural lakes, 0.04-0.74 mg/L for the reservoirs, and 0.01-0.53 mg/L for the artificial ponds. The World Health Organization (WHO) suggested a level of fluoride in drinking water of 0.5 to 1.5 mg/L. The study area had a fluoride deficiency of less than 0.5 mg/L in natural water bodies during the wet season (87.87%) and the dry season (93.93%), which might be a potential threat to dental health. Estimation Daily Intake (EDI) and Hazard Quotient (HQ) widely used health risk assessment methods were applied to the data in the current research to describe the non-carcinogenic risk of fluoride. All the calculated hazard quotient (HQ) values, both in the dry and wet seasons and in all age groups, were recorded as below 1. Both teenagers and children living in the central part of the study area are at higher risk than infants and adults. To evaluate model uncertainty, Monte Carlo simulations were employed. The outcome of the sensitivity analysis revealed that the major risks to the health of the inhabitants are the high content of fluoride and their daily intake of water.Öğe Surface deterioration of resin composites and enamel after toothbrush simulation with new and used toothbrushes(Mosher & Linder, Inc, 2024) Dindar, Mediha Buyukgoze; Tekbas-Atay, MeltemPurpose: To investigate the effect of toothbrushing with new and used toothbrushes on the surface of resin composites and dental enamel. Methods: The extracted human incisors were selected after vestibular enamel surfaces (ES) were examined. Disc-shaped specimens of direct composite (DC) and indirect composite (IC) were fabricated. Computer-aided design-computer-aided manufacturing (CAD-CAM) composite blocks (CC) were sliced in 2 mm thickness (n= 8). The surface roughness, gloss, and color were measured. The measurements were performed before and after 3 months of toothbrushing simulation (TBS) for 2,500 circular cycles. The wear index was calculated by using the ImageJ program. The specimens were subjected to an additional 2,500 cycles and the same measurements were repeated. Results: No significant increase in surface roughness values was observed in DC, IC, and CC groups after 3 and 6 months of TBS except in the ES group. The highest change in surface gloss was observed in the DC group. Although the wear index of toothbrushes increased over time, only the increase in the IC group was statistically significant (P= 0.033).
