Background: The purpose of this study is to evaluate the marginal adaptation of bulk-fill resin composites with different viscosities (paste-like and flowable) in Class II restorations using micro-CT imaging. Methods: Forty extracted human molars were used. Mesial and distal Class II box cavities (approximately 3 mm x 3 mm x 4 mm) were prepared for each tooth, with cavity floors located 1 mm below the enamel-cementum junction. Following adhesive application, teeth were restored using eight different groups: Group XB: X-tra Base Bulk-fill Flowable (VOCO), Group XF: X-tra Fill Bulk-fill (VOCO), Group FB: Filtek Bulk-fill Posterior (3 M ESPE), Group FF: Filtek Bulk-fill Flowable (3 M ESPE), Group BB: Beautifil-Bulk (SHOFU), Group BF: Beautifil-Bulk Flowable (SHOFU), and Group CO: “as a control group”, Clearfil Majesty Posterior (KURARAY) and Group CF: “as a control group”, Clearfil Majesty Flow + Clearfil Majesty Posterior (KURARAY). The restored teeth underwent an aging protocol involving 1000 cycles in a water bath fluctuating between 5 ± 1.0 °C and 55 ± 1.0 °C. Post-aging, teeth were immersed in 50% silver nitrate solution for 24 h and then in a film developer solution for 8 h. Microleakage analysis was performed using micro-CT, evaluated with 3D Slicer software. A two-way ANOVA was employed for statistical analysis. Results: Two-way ANOVA results indicated significant effects of both viscosity (p < 0.0001) and composite type (p < 0.0001) on marginal adaptation. Viscosity analysis (comparing flowable and paste-like) revealed no significant differences in the FB-FF, XB-XF and BB-BF groups but significant differences in the and CO-CF group, with flowable type exhibiting less microleakage than paste-like type. Conclusions: The study suggests that while the viscosity of bulk-fill composites did not significantly affect marginal adaptation, the brand of bulk-fill composite did influence it.

The aim of this study was to investigate the microshear bond strength (μSBS) of different universal adhesive systems applied to hybrid computer-aided design/computer-aided manufacturing (CAD-CAM) restorative materials repaired with a composite resin. Four types of CAD-CAM hybrid block materials-Lava Ultimate (LA), Vita Enamic (VE), CeraSmart (CS), and Shofu Block HC (SH)-were used in this study, in combination with the following four adhesive protocols: 1) control: porcelain primer + total etch adhesive (CO), 2) Single Bond Universal (SB), 3) All Bond Universal (AB), and 4) Clearfil Universal Bond (CU). The μSBS of the composite resin (Clearfil Majesty Esthetic) was measured and the data were analyzed using two-way analysis of variance and the Tukey test, with the level of significance set at p < 0.05. The CAD-CAM block type and block-adhesive combination had significant effects on the bond strength values (p < 0.05). Significant differences were found between the following pairs of groups: VE/CO and VE/AB, CS/CO and CS/AB, VE/CU and CS/CU, and VE/AB and CS/AB (p < 0.05). The μSBS values were affected by hybrid block type. All tested universal adhesive treatments can be used as an alternative to the control treatment for repair, except the AB system on VE blocks (the VE/AB group). The μSBS values showed variation across different adhesive treatments on different hybrid CAD-CAM block types.

SUMMARY: Objectives: The aim of this study was to measure the volumetric cuspal deflection of premolars restored with different paste-like bulk-fill resin composites using microcomputed tomography (micro-CT). Methods and Materials: A total of 35 freshly extracted human maxillary second premolars were selected for this study. Standardized large MOD cavities were prepared in each premolar with a bucco-lingual width of 4 mm and a cavity depth of 4 mm measured from the palatal cusp tip. After cavity preparation, all samples were scanned immediately using a micro-CT system. After the initial micro-CT scanning, restorative procedures were performed. Four groups received different paste-like bulk-fill composites—Beautifil-Bulk Restorative (BBR), Admira Fusion x-tra (AFX), x-tra fill, and Sonic Fill—and the control group received a conventional universal composite and Clearfil Majesty Esthetic (CME). Immediately after the restorative procedure, each tooth was scanned by micro-CT in the same manner as the initial scanning. The buccal and palatal regions of each restoration were evaluated separately in terms of cuspal deflection. One-way analysis of variance was used to compare the effect of the composite resin, and multiple comparisons were performed by the Tukey test with a level of significance of α = 0.05. Results and Discussion: Multiple comparisons showed that teeth restored with the conventional paste-like composite and CME (control) had significantly different cuspal deflection from those filled with paste-like bulk-fill composites (p<0.05). Among the bulk-fill composites, a significant difference was observed between BBR and AFX (p<0.05). Conclusions: Paste-like bulk-fill resin composites had significantly lower cuspal deflection than the conventional paste-like resin composite tested.

The aim of this study was to evaluate the cytotoxicity of contemporary flowable and paste-like bulk-fill dental composites by using a real-time cell analysis. In the present paper, cytotoxicity levels of five flowable, five paste-like bulk-fill composite materials and one conventional flowable, one conventional paste-like resin composite were examined on L929 mouse fibroblast cell line. After seeding 25,000 cells/300 μL/well cell suspensions into the wells of an E-plate, test materials were added and observed at every 30 min intervals for 72 h. Kruskal Wallis H and Mann Whitney U multiple comparison tests were used to analyze the results. Pre-reacted glass-ionomer (PRG) containing bulk-fill composites were severely toxic at all time points (24, 48 and 72 h, p70%) at 48 and 72 h. Flowable and paste-like composites of the same brand exhibited similar cytotoxic properties (p>0.05).

Dental trauma can lead to a wide range of injuries of which crown and root fractures are examples. Crown-root fractures often need complex treatment planning. This case report describes the use of MTA in the multidisciplinary management of a patient with a horizontally fractured central incisor and luxation in a different central incisor. A 42-year-old female patient presented within 1 h of receiving direct trauma to her maxillary area. Clinical examination revealed that the right and left maxillary central incisors presented mobility and sensitivity to percussion and palpation but no sensitivity to thermal stimulations. Occlusal displacement with extrusion in the left maxillary central incisor and luxation in the right maxillary central incisor was observed. Radiographic examination revealed horizontal root fracture at the apical third of the left maxillary central incisor. Root fracture in the right maxillary incisor was not observed. Endodontic and aesthetic restorative treatments were completed. MTA showed a good long-term outcome when used in root-fractured and luxated teeth. In addition, composite resin restoration provided satisfactory aesthetic results even after 15 months.