Objective: This study aimed to evaluate the fracture strength of teeth restored using fiber-reinforced direct restorative materials after endodontic treatment with a conservative mesio-occlusal access cavity design. Materials and methods: A total of 100 extracted intact mandibular first molars were selected and distributed into a positive control group where teeth left intact and the following four test groups comprised of teeth with conservative mesio-occlusal access cavities that had undergone root canal treatment (n = 20/group): access cavity without restoration (negative control), bulk-fill resin composite with horizontal glass fiber post reinforcement, fiber-reinforced composite with bulk-fill resin and bulk-fill resin composite. Following thermocycling (10,000 cycles), fracture resistance was measured using a universal testing machine. Statistical analyses (one-way analysis of variance and the Tamhane test) were performed, and statistical significance was set at p < 0.05. Results: Groups with minimally invasive access cavities had lower fracture strength than intact teeth, regardless of the restoration material (p < 0.05). Fiber-reinforced composite groups demonstrated higher fracture strength than bulk-fill resin composite alone (p < 0.05). Fracture types varied among groups, with restorable fractures predominant in the fiber-reinforced composite groups. Conclusion: This study suggests that using fiber-reinforced composite materials, especially in combination with bulk-fill resin composites, can effectively enhance the fracture strength of endodontically treated teeth with conservative access cavities. However, using only bulk-fill resin composite is not recommended based on the fracture strength results. Clinical significance: When teeth that undergo endodontic treatment are restored using a conservative access cavity design and fiber-reinforced composite materials, especially in combination with bulk-fill resin composites, the fracture strength of the teeth can be effectively increased.

This study aimed to evaluate the effects of different restorative techniques and materials on cuspal deflection and microleakage in MOD restorations. Eight groups were tested using incremental and bulk-fill techniques, with or without fiber reinforcement. The restorative materials included Filtek Z250 and Filtek Bulk-fill Posterior, while reinforcement materials such as Interlig glass fiber, EverX Posterior, and Surefill SDR were incorporated to assess their impact. In total, 96 freshly extracted, sound human maxillary first premolars were selected and stored in 0.1% thymol solution at 37 °C. The teeth were randomly assigned into eight groups (n = 12). Standardized MOD cavities were prepared, followed by endodontic treatment and sealing with glass ionomer cement. The groups were as follows: Group 1—Filtek Z250 applied incrementally in 2-mm layers; Group 2—U-shaped Interlig glass fiber followed by incremental Filtek Z250; Group 3—Filtek Bulk-fill Posterior using the bulk technique; Group 4—U-shaped Interlig glass fiber followed by Filtek Bulk-fill Posterior; Group 5—EverX Posterior followed by incremental Filtek Z250; Group 6—EverX Posterior followed by Filtek Bulk-fill Posterior; Group 7—Surefill SDR followed by incremental Filtek Z250; and Group 8—Surefill SDR followed by Filtek Bulk-fill Posterior. Cuspal deflection was measured using a digital micrometer with 0.05 μm precision. Microleakage was assessed using a 0.5% basic fuchsin dye solution at 37 °C for 24 h, followed by sectioning and examination under magnification. The lowest mean cuspal deflection was observed in Group 2 (15.8 μm), while the highest was in Group 5 (27.2 μm). Statistically significant differences were observed in cuspal deflection across the groups and over time (p < 0.05). Significant differences in microleakage scores were also found among the groups, indicating the impact of restorative materials and techniques on these outcomes (p < 0.05). This study demonstrated that Filtek Z250 and Filtek Bulk-fill Posterior showed different effects on cuspal deflection and microleakage. The use of glass fiber and EverX Posterior improved restoration performance by reducing polymerization effects. Surefill SDR also reduced cuspal deflection due to its low polymerization shrinkage. Clinically, selecting the appropriate restorative materials and techniques based on the extent of tooth structure loss can improve long-term outcomes.

Composite restorations often have gingival margins near the cemento-enamel junction (CEJ), where the microleakage of these margins can significantly contribute to the restoration failure, especially in the cervical lesions. It is important to determine the microleakage is crucial, as it typically occurs through the interfacial gap between the tooth and the restoration. Various resin composites and techniques have been developed to minimize this gap and reduce the risk of microleakage. The aim of this in vitro study was to evaluate the levels of microleakage of different modes of a universal adhesive and two novel resin composites in restoring class V cavities in the central incisors. Sixty-six freshly extracted sound human central incisors of the similar size were randomly assigned to 2 groups (n = 33 per group) according to the brand of resin composite. Each group was further divided into 3 subgroups based on the Scotch Bond Universal (3 M ESPE, Saint Paul, MN, USA) application protocol used: (a) total etch, (b) self-etch and (c) selective etch. After composite restoration completed with Omnichroma (Tokuyama Dental Corp., Tokyo, Japan) and Filtek Universal Restorative (3 M ESPE, Saint Paul, MN, USA), each tooth was immersed in a 0.5% basic fuchsin dye solution at 37C0 for 24 h. After dye penetration, teeth were sectioned and evaluated with conventional (scoring) and digital methods (ImageJ). The intra- and inter-examiner agreement was estimated according to the Kappa statistics and the results were analyzed with the one-way ANNOVA and the Kruskal–Wallis test (p < 0.05). The rates of microleakage of the gingival and incisal margins are statistically similar, regardless of the composite brand and the method of application of the universal adhesive. The microleakage exhibited by current adhesives and resins is independent of the adhesive application mode and measurement method.

Amaç: Bu çalışmanın amacı, üniversal rezin kompozitlerin renk stabilitesi ve yüzey özellikleri üzerine yaygın kullanılan içeceklerin etkilerini in vitro olarak incelemektir. Gereç ve Yöntemler: Üç üniversal rezin kompozit (Omnichroa, Estelite Sigma Quick, Filtek Universal Restorative) ve 3 farklı içecek (kahve, portakal suyu ve kola) incelenmiştir. Distile su kontrol grubunda kullanıldı. Yüzey pürüzlülüğü ve renk stabilitesi değerlendirilmesi için her materyalden her içecek için disk şeklinde örnekler hazırlandı (n=10). Ölçümler polimerizasyondan 24 saat sonra ve içeceklerde bekletme işlem sorasında tekrarlandı. Ayrıca, su emilimi için ISO 4049:2009 standartları doğrultusunda her materyalden 10 tane örnek hazırlandı. Elde edilen veriler istatistiksel olarak tek yönlü varyans analizi, post hoc Tukey testi kullanılarak analiz edildi (p<0.05). Bulgular: Distile su grupları tüm materyallerde en az ΔE00 değerlerini gösterdi. Her materyalde kahvede bekletme sonrası istatististiksel olarak anlamlı bir renk değişimi tespit edildi (p<0.05). İçeceklerin restoratif materyallerin pürüzlülük değerlerinde anlamlı farklılığa yol açmadığı görüldü. Omnichroma’nın tüm içeceklerde diğer restoratif materyallere göre anlamlı derecede yüksek pürüzlülük gösterdiği saptandı (p<0.05). Sonuç: Renklenme estetik restorasyonda önemli bir parametredir. Estetik restoratif materyallerin hem yüzey hem renk özellikleri dış kaynaklı renklendiricilerden etkilenmektedir. Bundan dolayı, hekimler estetik restoratif materyalleri kullandıkları tedavi yaklaşımlarında bu konun bilincinde olmalı ve hastalarını bilgilendirmelidirler.

Aim: This study aimed to evaluate the effect of bevel preparation on the color adjustment potential (CAP) of three universal oneshade and one conventional resin composite used in anterior restorations. Materials and Methods: Three universal one-shade (Omnichroma, Vitra APS Unique, Charisma Topaz One and one conventional resin composite (Estellite Sigma Quick) were tested. Standardized cavities (6 mm diameter, 2 mm depth) were prepared in A2-shade acrylic molds, either without bevel or with a 2 mm, 45° bevel. Each group consisted of ten specimens (n=10). Restorations were placed in a single increment, lightcured, polished, and stored in distilled water for 24 hours. Color parameters (L*, a*, b*) were measured using a spectrophotometer (VITA Easyshade V), and ΔE values were calculated with the CIEDE2000 formula. The color adjustment potential index (CAP-I) was determined as CAP-I = 1 – (ΔEDUAL/ΔESINGLE). Data were analyzed using the t- test, ANOVA and Tamhane post hoc tests (α=0.05). Results: CAP-I values ranged from 0.57 to 0.86 in non-beveled and 0.85 to 0.94 in beveled groups. No statistically significant differences were found between bevel and and non-bevel designs except Omnichroma group (p=0.003). Omnichroma showed the lowest CAP in non-beveled groups (p<0.05), whereas Estellite demonstrated the highest overall values. Conclusion: Bevel preparation did not significantly affect the color adjustment potential of tested composites except Omnichroma groups. The optical characteristics of restorative materials appear to have a greater influence than cavity design on esthetic blending. Therefore, appropriate composite selection remains critical for achieving natural integration in anterior restorations.