Pattern of Hydroxyapatite Crystal Growth on Bleached Enamel Following the Application of Two Antioxidants: An Atomic Force Microscope Study.

OBJECTIVES: This study observed the topographical pattern of hydroxyapatite deposition and growth (D&G) on bleached enamel following application of two antioxidants (sodium ascorbate and catalase) using atomic force microscope. STUDY DESIGN: Twenty enamel specimens (4×3×2mm), prepared from extracted impacted third molars, were mounted in self-cure acrylic and randomly grouped as: Group I-untreated; Group II- 35%H2O2; Group III- 35%H2O2 + artificial saliva; Group IV- 35%H2O2 + catalase+ artificial saliva; Group V- 35%H2O2 + sodium ascorbate+ artificial saliva. Groups I and II were observed immediately after treatment. Groups III-V were observed after 72 hrs. Roughness average was also calculated and analyzed with non-parametric Kruskall-Wallis ANOVA and Mann-Whitney tests. RESULTS: H2O2 dissolved matrix, exposed hydroxyapatite crystals (HACs), causing dissolution on the sides of and within HACs and opening up of nano-spaces. Artificial saliva showed growth of dissoluted crystals. Antioxidants+saliva showed potentiated remineralization by D&G on dissoluted HACs of bleached enamel. Catalase potentiated blockshaped, while sodium ascorbate the needle-shaped crystals with stair-pattern of crystallization. Evidence of oxygen bubbles was a new finding with catalase. Maximum roughness average was in group V followed by group II > group IV > group III > group I. CONCLUSION: Post-bleaching application of catalase and sodium ascorbate potentiated remineralization by saliva, but in different patterns. None of the tested antioxidant could return the original topography of enamel.

Autogenous tooth fragment reattachment: a multidisciplinary management for complicated crown-root fracture with biologic width violation.

Fractures of multiple permanent anterior teeth can be a traumatic experience for children, with functional, esthetic and psychological aspects. The treatment of complicated crown-root fractures (CRFs) is more challenging when the biologic width is violated. This paper presents a case of 12-year boy with complicated CRF of teeth #12 and #21, and horizontal crown fracture of tooth #11. It was managed by endodontic treatment, mucoperiosteal surgery with osteotomy to visualize the fracture line for fragment reattachment, followed by fiber-post placement and restoration with polycarbonate crowns. Clinical and radiographic evaluation after 6 months was satisfactory with adequate functional and esthetic results.