The aim of this study is to evaluate the effect of an office bleaching agent on the color of various single-shade resin composites. Three single-shade resin composites were tested in this study. Thirty disk-shaped specimens were prepared with a diameter of 10 mm and a height of 1 mm, and they were divided into three groups (n = 10). After color measurements, 40% hydrogen peroxide containing bleaching agent gel was applied to all the specimens. Baseline and final color measurements were performed using a clinical spectrophotometer. Statistical analyses were performed. All bleached specimens had clinically incomprehensible color changes (ΔE < 3.3). Comparisons for single-shade composites revealed no statistically significant color difference between groups. With the limitation of this study in mind, color changes in single-shade resin-composites after office bleaching were found to be clinically acceptable. It may be appropriate to use single-shade composites that shorten the in-chair clinical time by facilitating shade selection.

Objective: The objective of this study was to evaluate the compressive strength, flexural strength and flexural modulus of high-viscosity, low-viscosity bulk-fill, and conventional nano-hybrid resin composite materials alone and when covered with nano-hybrid resin composite at different incremental thicknesses on the bulk-fill composites. Materials and Methods: Specimens (N=60) were fabricated from the following materials or their combinations (n=10 per group): a) conventional nano-hybrid composite Z550 (FK), b) high-viscosity bulk-fill composite (Tetric N Ceram-TBF), c) low-viscosity bulk-fill composite SDR (SDR), d) Sonicfill (SF), e) SDR (2 mm)+FK (2 mm), f) SDR (4 mm)+FK (4 mm). After 24 h water storage, compressive strength was measured in a universal testing machine (1 mm/min). Additional specimens (N=40) (25x2x2 mm3) were made from FK, TBF, SDR and SF in order to determine the flexural strength and the flexural modulus, (n=10) and subjected to three-point bending test (0.5 mm/min). Data were analyzed using one-way ANOVA and Tamhane’s T2 post-hoc tests (p<0.05). Results: The mean compressive strength (MPa) of the nano-hybrid composite (FK) was significantly higher (223.8±41.3) than those of the other groups (123±27 - 170±24) (p<0.001). SDR (4 mm)+FK (2 mm) showed significantly higher compressive strength than when covered with 4 mm (143±30) or when used alone (146±11) (p<0.05). The mean flexural strength (159±31) and the flexural modulus of FK (34±7) was significantly higher than that of the high- or low-viscosity bulk-fill composites (p<0.001). The mean flexural strength of SF (132±20) was significantly higher compared to TBF (95±25) (p<0.05). Conclusion: Bulk-fill resin composites demonstrated poorer mechanical properties compared to nano-hybrid composite but similar to that of SF. Increasing the thickness of low-viscosity bulk-fill composite (SDR) from 2 to 4 mm underneath the nano-hybrid composite (FK) can improve the mechanical properties of the bulk-fill composites. KeywordsBulk-fill composites; Compressive strength; Flexural modulus; Flexural strength; Mechanical properties.

The surface roughness of different glass–ionomer-based materials and their shear bond strength with a resin composite with and without thermal cycling were evaluated. Ketac Molar (KM, 3M ESPE, St. Paul, MN, USA), Glass Carbomer (GC, GCP Dental, Leiden, The Netherlands), Bioactive (BA, PULPDENT, Corporation, Watertown, MA, USA) and Fuji II LC (FJ, GC, Tokyo, Japan) were used to prepare the specimens and they were kept in distilled water at 37 °C for 24 h. The surface roughness of the specimens was measured with a profilometer (n = 6). A universal adhesive resin was applied on glass–ionomer materials and cylindrical universal composites were applied and polymerized, respectively (n = 16). The specimens were divided into two subgroups. The first subgroup was subjected to thermal cycling. Shear bond strength was investigated for both subgroups (n = 8). Stereomicroscopy and SEM examinations were performed. The roughest surface was obtained in the GC group (p < 0.05). The shear bond strength of the specimens without thermal cycling was higher than that of those with thermal cycling (p < 0.05). The lowest shear bond was measured in the GC group (p < 0.05). Although FJ, KM and BA have been observed to be suitable materials for clinical use, BA, in particular, is evidenced to become the best option among the materials we tested. GC cement’s long-term performance needs to be improved.

Objectives: The aim of thi s 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.

This study assessed the color-matching capability of three single-shade composites that employ simulated resin 3D-printed cavities with different cavity depths using CIELAB and CIEDE2000 formulas. A cylindrical model with standardized cavities was generated. One hundred and fifty blank specimens were fabricated and divided into three groups ( n = 50) and then into five subgroups. The five subgroups included four groups of specimens with 0.5, 1, 2, and 4 mm cavities and a control group of specimens without cavities ( n = 10). Cavities were filled with Vittra Unique (VU), Omnichroma (OC), and OptiShade (OS). Color measurements were done using a clinical spectrophotometer. The color differences for all composites were calculated as Δ E and Δ E ₀₀ using CIELAB coordinates. The color parameter data were analyzed ( α = 0.05). OS had significantly lower ∆ E and ∆ E ₀₀ values than the other composites for all layer thicknesses ( p < 0.05). VU, OC, and OS had the lowest ∆ E and ∆ E ₀₀ values at 0.5 mm ( p < 0.05). Color matching of monochromatic composites decreased as the layer thickness increased. OS achieved the best color matching in this study. Single-shade composites are important for reducing chairside time and gaining confidence in clinical practice. CIELAB and CIEDE2000 color difference formulae can be used in different studies with similar results.

Aim: Although the shelf life is a key property of dental composites and bonding agents, these materials may often be used in simple procedures after expiration. In this study, the microleakage of two year expired and non-expired dental composites (Filtek Ultimate Universal A2 Enamel, 3M ESPE, USA, and Tetric N Ceram A2, Ivoclar Vivadent, Schaan, Liechtenstein) and a universal bonding system (Single Bond Universal, 3M ESPE, USA) was examined. Materials and Methods: In 40 freshly extracted human molars, two standardized Class II cavities (buccolingual and mesiodistal width of 3 mm and 4 mm, respectively) were prepared (80 cavity preparations). The teeth were thermocycled in distilled water for 1000 cycles in a 5°C to 55°C water bath. Next, the teeth and their apical foramens were coated with water resistant nail varnish, except for 1 mm around the restoration–tooth interface, and retained in a 1% methylene blue solution. After 24 h, the specimens were cut into two halves and analyzed using a stereomicroscope. Scanning electron microscopy images of two samples of the groups were obtained. Results: The Kruskal–Wallis test indicated no significant differences between the groups ( P < .05). The occlusal median scores were not significant ( P = .99). Moreover, the gingival median scores were not significant ( P = .48). No difference was found between the occlusal and gingival values in any group ( P > .05). Conclusion: These findings indicated that two-year-expired dental composites and bonding agent, which were maintained under proper conditions, do not have any significant difference in terms of the microleakage.