Bleaching effectiveness and cytotoxicity of new experimental formulation of niobium-based bleaching gel.

OBJECTIVES: The development of new bleaching agents with minimum concentration of hydrogen peroxide (HP), without adverse effects, and with bleaching effectiveness, has great clinical relevance. The aim of this study was to evaluate the bleaching efficacy and cytotoxicity of a new niobium-based bleaching gel, compared to already available HP-based gels. MATERIALS AND METHODS: For the bleaching efficacy analysis, 40 bovine incisors were randomly divided into 4 groups according to the established bleaching protocol: control, untreated; 35HP, 35% HP bleaching gel; 6HP, 6% HP bleaching gel; NbHP, niobium gel associated with 3% HP gel. The color variation was measured in a spectrophotometer and the values of ΔL, Δa, Δb, and ΔE obtained. For the cell viability assay by MTT, MC3T3 cells were exposed to bleaching gel extracts (1:500, 1:250, 1:125 dilutions; immediately and 24 h). Statistical tests were performed (P < 0.05). RESULTS: The color alteration for all bleaching gels was significant compared to control (P < 0.05), but the NbHP gel showed a significant ΔE than other gels, with expressive color alteration at 14 days (P < 0.05). The 35HP showed high cytotoxicity regarding control and the most groups in all periods and extracts analyzed (P < 0.05), while the NbHP showed greater cell viability than control in the immediate period, dilution of the 1:500 and superior to 6HP in the most extracts at 24 h. CONCLUSION: The new experimental niobium-based gel has bleaching efficacy similar to that of gels with a high concentration of HP, and it has high cytocompatibility. CLINICAL RELEVANCE: The use of this new generation of niobium-based whitening gel associated with a low concentration of hydrogen peroxide represents the possibility of a tooth whitening with lower dentin sensitivity.

Adaptable fiberglass post after 3D guided endodontic treatment: Novel approaches in restorative dentistry.

OBJECTIVE: The rehabilitation of extensively damaged teeth with great structural loss and calcified root canals represents a challenge for dentistry. Classically, this restorative procedure of endodontically treated teeth involves intraradicular post placement. Retentive function post that can closely adapt to the root canal without the excessive wear of intraradicular dentin has a fundamental importance to ensure the longevity of the restoration. CLINICAL CONSIDERATIONS: This report presents a clinical case of 3D guided access to a severely calcified pulp canal followed by the cementation of a fiberglass post that is adaptable to the root canal and prosthetic rehabilitation with full ceramic crown. CONCLUSIONS: 3D guided access allowed conservative and safe root canal treatment. The adaptable fiberglass post meets the specific needs of the described case and has a simple technique and low cost. CLINICAL SIGNIFICANCE: Guided endodontics is a minimally invasive approach for teeth with calcified root canals. The post used in this study meets the demands of teeth endodontically treated with conservative techniques. The professional should not need to adapt the anatomy of the root canal to the anatomical reality of the post. This one adapts itself to the shape of the canal.

Light transmission through a translucent fiber post.

This study is a quantitative assessment of the luminous energy transmitted through different translucent fiber posts. After embedding the posts in black resin, the blocks were submitted to sequential cuts in a precision machine, and depths of 16 mm, 12 mm, 8 mm, and 4 mm were assessed for light transmission with a digital photometer. The quantitative analysis showed significant differences between different posts and depths. Furthermore, the values obtained revealed that the quantity of luminous energy transmitted depends on the type of post and that for all of them there was a significant reduction of the quantity of light transmitted as the depth increased. Even without the post, the luminous intensity inside the canal seems to decrease to levels that are insufficient for polymerization, especially in the apical third.