Clinical Relevance: Bleached enamel is not conducive to immediate composite restoration. The use of oligomeric proanthocyanidin complexes as antioxidants enables an immediate composite restoration post bleaching.

Treatment of a tooth with necrotic pulp and open apex is a special challenge to the clinicians. Apexification with calcium hydroxide and MTA barrier technique fails to induce continued root maturation which makes the tooth susceptible to root fracture. Hence, an ideal outcome for such a tooth should be regeneration of pulp like tissue into the root canal capable of continuing normal root maturation. This study aims to compare the effect of Platelet Rich Fibrin (PRF), induced bleeding technique and Platelet Rich Plasma (PRP) in the revascularization of tooth with necrotic pulp and open apex. The main objectives of the study were to: (a) Radiographically evaluate the continuation of root development, increase in the dentin wall thickness and narrowing of canal space, apical closure and resolution of the periapical lesion; and to (b) To clinically evaluate the response to pulp sensibility testing and response to percussion and palpation tests. Sixty patients (6 to 28 years) with necrotic immature permanent tooth were randomly categorised into three groups after the root canal disinfection procedure. PRF as scaffolding material (Group A: n=20), revascularization with conventional induced bleeding technique (Group B: n=20), and PRP as the biomaterial (Group C: n=20). The primary outcome variable was measured using Periapical Index (PAI) (for periapical healing), Chen and Chen index (for apical responses), Schei's ruler (for root lengthening and root thickening) and other clinical parameters. The Chi-square test was used to interpret the data among the three groups at the end of 12 months for the variables root lengthening and lateral wall thickness. ANOVA test was performed to compare the mean of the PAI scores of the three groups at preoperative stage and 12 months. If statistically significant, Bonferroni test was done to compare the outcome among the three groups. The significant level was set at p<0.05. Kappa agreement was used to see whether the clinical criteria of success (asymptomatic) were in agreement with radiographic criteria. At the end of 12 months, patients presented with no pain and no signs of reinfection or no radiographic enlargement of the pre-existing apical pathosis in all the three groups. PRP was better than PRF and induced bleeding technique with respect to periapical wound healing when used in the regenerative endodontic procedures. The groups were comparable on grounds of root lengthening and lateral wall thickening. Type 3 apical response was the most common apical response in all the three groups. On analysing the pros and cons of the techniques performed, it is wise to establish induced bleeding technique as the standard endodontic procedure for revascularization of a non vital immature permanent tooth.

Objective: The aim of this in vitro study was to evaluate and compare the effect of 10% sodium ascorbate, 6.5% proanthocyanidin, and 5% lycopene on the bond strength of composite resin to bleached enamel. Materials and Methods: Labial enamel surfaces of 100 extracted human maxillary central incisors were used in this study. Twenty teeth served as group I (control) and received no bleaching treatment. The remaining 80 teeth were randomly divided into four groups of 20 teeth each, based on the antioxidant used as follows: group II- bleaching with 35% carbamide peroxide gel for 30 min without the use of an antioxidant, group III- bleaching followed by use of 10% sodium ascorbate solution, group IV- bleaching followed by use of 6.5% proanthocyanidin, and group V- bleaching followed by use of 5% lycopene. These groups were further subdivided into two subgroups of 10 teeth each, based on whether composite buildup was done immediately (subgroup A) or after a delay of 2 weeks (subgroup B) post bleaching. Shear bond strength of the specimens was tested under universal testing machine. The data were tabulated and statistically analyzed. Results: Significantly higher shear bond strength values were observed in teeth treated with control group prior to bonding, followed by sodium ascorbate group. Conclusion: Within the limitations of this study, it can be concluded all the antioxidants used in this study increased the bond strength of bleached enamel. Among the antioxidant groups, sodium ascorbate showed significantly higher bond strength compared to proanthocyanidin and lycopene.