Comparison of the mechanical properties of two giomer based bulk-fill, a hybrid bulk-fill and a nanohybrid composites with different application protocols: In vitro study

Amaç: Bu çalışmada, farklı tabaka kalınlıklarında uygulanan düşükve yüksek viskoziteli bulk-fill giomerler, bir nano-hibrit kompozit ve birbulk-fill hibrit kompozitin basma dayanımlarıyla bükülme dayanımlarınınkarşılaştırılması amaçlanmıştır. Gereç ve Yöntemler: Kompozit malzeme lerin basma dayanımlarının değerlendirilmesi amacıyla 6 grupta (n=10) top lam 60 adet silindir şeklinde örnek (6x3mm) hazırlanmıştır. Deney grupları aşağıdaki şekildedir:Grup 1 (G1) Tetric N-Ceram (TNC) (2+2+2 mm),Grup 2 (G2) Tetric N-Ceram Bulk-Fill (TBF) (4+2 mm),Grup 3 (G3) Beautifill Bulk-Fill Flowable (BBF) (4+2 mm),Grup 4 (G4) Beautifill Bulk Restorative (BBR) (4+2 mm),Grup 5 (G5) 2 mm BBF+4 mm BBR,Grup 6 (G6) 4 mm BBF+2 mm BBR.Örnekler 1 mm/dk kafa hızında basma dayanımı testine tabi tutulmuştur.Bükülme dayanımı ve bükülme modülüsünün hesaplanabilmesi amacıyla40 adet (25x2x2 mm) (n=10) kompozit örnek hazırlanmış [TNC (GF1), TBF(GF2), BBR (GF3), BBF (GF4)] ve 3 nokta bükülme testi (0,5 mm/dk) ger çekleştirilmiştir. Elde edilen veriler, tek yönlü ANOVA ve Tamhane T2 test leri kullanılarak değerlendirilmiştir (p0,05). GF4’ün ortalama bükülme dayanımı, GF1, GF2 ve GF3 grupla rından istatistiksel olarak anlamlı derecede yüksek bulunurken, diğer grup lar arasında anlamlı bir fark bulunamamıştır. Sonuç: En yüksek basma vebükülme dayanımı değerleri, bulk-fill giomerlerle elde edilmiştir. BBR al tında uygulandığında BBF kalınlığını 2 mm’den 4 mm’ye çıkarmak, basmadayanımını istatistiksel olarak anlamlı şekilde artırmıştır.Objective: This study evaluated the compressive strengthof low and high viscosity bulk-fill giomers, a nano-hybrid and a bulk-fillhybrid composites with varied layer thicknesses and evaluated their flex ural strength. Material and Methods: Sixty cylindrical specimens (6x3mm) in 6 subgroups were fabricated (n=10). The restorations were madeusing either:Group 1 (G1) Tetric N-Ceram (TNC) (2+2+2 mm)Group 2 (G2) Tetric N-Ceram Bulk-Fill (TBF) (4+2 mm),Group 3 (G3) Beautifill Bulk-Fill Flowable (BBF) (4+2 mm),Group 4 (G4) Beautifill Bulk Restorative (BBR) (4+2 mm),Group 5 (G5) 2 mm BBF+4 mm BBR,Group 6 (G6) 4 mm BBF+2 mm BBR.Compressive tests were performed at 1 mm/min. To determine the flexuralstrength and the flexural modulus, 40 specimens for each resin compositewere prepared [TNC (GF1), TBF (GF2), BBR (GF3), BBF (GF4)] (n = 10)(25×2×2 mm) and subjected to three-point bending test (0.5 mm/min). Datawere analyzed using one-way ANOVA and Tamhane’s T2 tests (p0.05). The mean flex ural strength of the GF4 was found statistically significantly higher thanthe GF1, GF2 and the GF3 groups, where no significant difference de tected between the other groups. Conclusion: The compressive and theflexural strength values of the bulk-fill giomers were found to be the high est. Increasing Beautifill Bulk Restorative (BBF) thickness 2mm to 4mmunder (Beautifill Bulk-Fill Flowable) BBR, improved the compressivestrength significantly

Frequency and Localization of Overhanging Restorations

Objectives: The aim of this retrospective study was to determine the frequency and localization of the overhanging restorations by observing patients’ routinely taken panoramic radiographs. Materials and Methods: The panoramic radiographs of 4,960 patients who applied to a dental clinic in University between 2015 and 2016 and had one or more previous restorations were retrospectively examined. The study group included 243 patients (133 females and 110 males) with a mean age of 39.7 ± 12.5 years. Superposed interdental areas were not evaluated. Frequency distributions and percentages were calculated for the categorical data as to the surface of the maxillary-mandibular premolar and molar teeth, also the presence or absence of root canal treatment. Chi-square tests were used to compare data relating to the localization and frequency of overhanging restorations. Results: In the radiological evaluation of 243 patients, a total of 280 overhanging restorations were detected. Root canal treatment was present in 45.4% of the teeth with an overhanging restoration. The frequency of overhanging restorations in the maxilla was significantly higher (60.4%) than that of the mandible (39.6%), (p<0.05). The frequency of overhanging restorations in molar teeth (82.9%) was significantly higher than that of premolar teeth (p<0.05). Of all the overhanging restorations, 90.4% were in Class II cavities and 9.6% were in mesio-occluso-distal (MOD) cavities. More than half (57.3%) of the overhanging margins in the Class II restorations were distal; 42.7% were mesial surfaces (p<0.05). The most frequent restorations with overhanging were found in the maxillary molars (49.6%) and the least frequent were in the premolar teeth of the mandible (6.4%).   Conclusions: The restorations with overhanging margins determined most often at the disto-occlusal margins of the maxillary molars. The frequency of overhanging restorations was higher in areas that are difficult to reach during treatment

Effect of surface sealant on the surface roughness of different composites and evaluation of their microhardness

PurposeThe aim of this study was to evaluate the effect of a surface sealant on the surface roughness of different composites and compare their microhardness values.Materials and MethodsSixty disc-shaped specimens were prepared and assigned to 6 groups (n = 10). Groups were prepared as follows; Group 1 (Herculite XRV Ultra), Group 2 (Beautifil Bulk Restorative) and Group 3 (Filtek Bulk Fill Posterior Restorative). Groups 4, 5, and 6 were prepared by applying a surface sealant (BisCover LV) on the specimens in groups 1, 2 and 3. Surface hardness of the discs in group 1, 2, and 3 and surface roughness of the discs in all groups were measured using the Vickers hardness test and a profilometer, respectively. One-way ANOVA was used to test for differences among the groups.ResultsNo significant differences were observed in the microhardness and roughness between the experimental and control groups for each restorative materials. Group 3 showed the highest surface hardness and group 4 showed the lowest surface roughness values.ConclusionUsing the BisCover LV resin after the polishing step has no significant effect on the surface roughness. The highest hardness values were obtained for the Filtek Bulk Fill Posterior Restorative after the polishing step. The smoothest surfaces were obtained for all experimental groups using the BisCover LV resin after the polishing step, Herculite XRV Ultra showed lower average roughness values than the other materials

Effect of desensitizers on the microleakage of previously restored Class V resin composite restorations

WOS: 000379133600003Objectives: The aim of this in vitro study was to evaluate the effect of different desensitizers' application on the microleakage of previously restored Class V composite resin restorations. Materials and methods: Class V cavities were prepared on the buccal surfaces of 40 extracted human third molars. Forty box-shaped cavities were divided into four groups, based on the desensitizers used (n = 10). All teeth were restored with the same bonding agent and composite material. No desensitizer was applied in the control group. In the experimental groups, BisBlock, Gluma and Universal bonding agents were the desensitizers. The desensitizers were applied after completion of composite restorations according to manufacturers' instructions. All specimens were then thermocycled at 5-55 degrees C, with a 10-s dwell time for 500 cycles. The samples were then immersed in 0.5% methylene blue dye for 24 h, sectioned into two equal halves, evaluated for microleakage using a stereomicroscope at 30x magnification and scored on a scale of 0-3. The data were analysed using the Kruskal-Wallis test at the significance level p 0.05). However, based on the obtained numerical values in our study, while the BisBlock and bonding groups showed lower microleakage at the occlusal margin, BisBlock, Gluma and bonding group showed lower microleakage at the gingival margin compared to the control group. Conclusions: The application of desensitizers as a post-treatment option could be considered an advisable procedure to minimize microleakage

Effect of different antioxidants on the microtensile bond strength of an adhesive system to sodium hypochlorite-treated dentin

WOS: 000367258100003PubMed ID: 26734673Purpose: To evaluate the effects of different antioxidant treatments on the microtensile bond strength of an adhesive system to sodium hypochlorite (NaOCl)-treated dentin. Materials and Methods: Thirty extracted third molars were sectioned 3 mm below the occlusal surface and divided into six groups according to the antioxidant treatment received: control group: distilled water; NaOCl group: 5.25% NaOCl and distilled water; proanthocyanidin (PA) group: 5.25% NaOCl, 5% PA and distilled water; 1-week storage group: 5.25% NaOCl and storage for 1 week in distilled water; Accel group: 5.25% NaOCl, Accel, and distilled water; noni group: 5.25% NaOCl, noni fruit juice, and distilled water. NaOCl, PA, Accel, noni, and distilled water were administered for 30 s, 10 min, 30 s, 10 min, and 30 s, respectively. A self-etching adhesive system (Single Bond Universal Adhesive) was applied to each specimen and a resin composite (Filtek Z550) was built up to a height of 5 mm on the dentin surface. Each specimen was serially sectioned to obtain sticks with a cross-sectional area of 1 mm(2), and their microtensile bond strength was determined. Statistical differences between groups were analyzed using one-way ANOVA and Tamhane's T2 test. Results: Microtensile bond strength in the NaOCl group was significantly lower than in all other groups. However, there were no significant differences in the bond strength between the groups treated with different antioxidants. Conclusions: NaOCl significantly reduced the microtensile bond strength of the adhesive system. The application of PA, Accel, and noni fruit juice to NaOCl-treated dentin significantly improved the microtensile bond strength

Color Stability of Composites After Short-Term Oral Simulation: An In Vitro Study

BACKGROUND: Although most of the studies investigated color stability of different restorative materials, evaluation of color stability of composites after immersion in multiple beverages in the same day by an in vitro oral simulation study is unclear. OBJECTIVE: To assess color change of different restorative materials at the end of days 1, 14, and 30 of immersion in multiple liquid types to mimic the oral environment in vitro. METHOD: Ten disc-shaped specimens were made from each of four different resin composites (Filtek Z250, Voco x-tra base, Beautifil Flow Plus, Beautifil II). Baseline color value of each sample was measured using a spectrophotometer. Each composite was respectively immersed in coffee, an orange/pomegranate juice mixture, black tea, and a mouth rinse on the same day to mimic daily liquid consumption of individuals. Color measurements were taken after 1, 14, and 30 days by spectrophotometer and color change values were calculated. Statistical analyses were executed by one-way ANOVA/Tukey HSD and repeated-measures ANOVA. RESULTS: All materials showed significant color change after 1, 14, and 30 days (P < 0.01) of immersion in liquids, with the lowest color alteration observed at the 1(st) day and the highest observed after the 30(th) day. Among the materials tested, at each time point (1, 14, and 30 days), the lowest color alteration was detected in Filtek Z250 and the highest color alteration was detected in Beautifil II. CONCLUSION: Color alteration of composite resins is affected by composite type and storage time. With the exception of 1 day of storage, color changes of all materials were substantial and clinically unacceptable