Characterization of the apical bridge barrier formed following amelogenin apexification.

BACKGROUND: Recombinant amelogenin protein (RAP) is reported to induce complete root apex formation in dog model when used as apexification therapy. It also induces pulp regeneration in 85% of the treated group. Thus, the aim of this study was to investigate the nature of the remaining regenerated calcified tissues of the RAP group that showed no pulp regeneration compared to the calcium hydroxide treated group (CH). METHODS: A total of 240 dogs' open apex root canals were used, after establishment of canals contamination. Canals were cleaned, irrigated, and filled with RAP as an apexification material and compared with CH. Treated teeth were assessed by H&E, trichrome staining, and/or immunohistochemistry technique, at 1, 3, and 6 months. RESULTS: A time-dependent increase in the calcified tissue barrier was observed in the apex of the RAP-treated group compared to the CH-treated group. The newly formed dentin in this RAP group was mainly tubular dentin and was functionally attached to the bone by periodontal ligament, while the CH group showed dentin-associated mineralized tissue (DAMT) associated with the newly formed apical barrier. CONCLUSIONS: Out results suggest that RAP can be used as novel apexification material, resulting in a thickening and strengthening of the canal walls, and achieving apical closure.

Formulation of Saudi Propolis into Biodegradable Chitosan Chips for Vital Pulpotomy.

BACKGROUND: Propolis has been widely used to treat oral cavity disorders, such as endodontal and periodontal diseases and microbial infections. OBJECTIVE: The study aimed at the formulation of commercial Saudi propolis into biodegradable chitosan chips and evaluation of its effectiveness as a pulpotomy agent. METHODS: The standardization of 80% ethanolic propolis extract was performed regarding its total phenolic content, total flavonoid content, quantitative estimation of main polyphenolic constituents and antioxidant activity. Chitosan chips containing propolis extract were prepared by the solvent/ casting method. The investigated variables were % of chitosan polymer (2, 2.5 and 3%), % of plasticizer (1, 5 and 10%) and incorporation of different concentrations of hydroxypropyl methylcellulose (5, 10 and 20% of polymer weight). The chips were characterized for weight and thickness uniformity, content uniformity, pH, percentage moisture loss, swelling index, tensile strength and in vitro propolis release. The optimal propolis chip formulation was further investigated in dogs regarding the short term response of primary dental pulp to propolis chips compared with the most commonly used formocresol preparation. RESULTS: The prepared films were flexible and demonstrated satisfactory physicochemical characteristics. The optimal formulation showed an initial release of about 41.7% of the loaded propolis followed by a sustained release extended up to 7 days. The kinetics study demonstrated that propolis release was controlled by Fick´s diffusion. The optimal propolis chip formulation resulted in less pulpal inflammation compared to formocresol, and produced hard tissue formation in all specimens. CONCLUSION: Formulation of commercial Saudi propolis as a biodegradable chitosan chip is an effective alternative to the commercially available chemical agents for the treatment of vital pulpotomy.

Recombinant Amelogenin Protein Induces Apical Closure and Pulp Regeneration in Open-apex, Nonvital Permanent Canine Teeth.

INTRODUCTION: Recombinant DNA-produced amelogenin protein was compared with calcium hydroxide in a study of immature apex closure conducted in 24 young mongrel dogs. METHODS: Root canals of maxillary and mandibular right premolars (n = 240) were instrumented and left open for 14 days. Canals were cleansed, irrigated, and split equally for treatment with recombinant mouse amelogenin (n = 120) or calcium hydroxide (n = 120). RESULTS: After 1, 3, and 6 months, the animals were sacrificed and the treated teeth recovered for histologic assessment and immunodetection of protein markers associated with odontogenic cells. After 1 month, amelogenin-treated canals revealed calcified tissue formed at the apical foramen and a pulp chamber containing soft connective tissue and hard tissue; amelogenin-treated canals assessed after 3- and 6-month intervals further included apical tissue functionally attached to bone by a periodontal ligament. In contrast, calcified apical tissue was poorly formed in the calcium hydroxide group, and soft connective tissue within the pulp chamber was not observed. CONCLUSIONS: The findings from this experimental strategy suggest recombinant amelogenin protein can signal cells to enhance apex formation in nonvital immature teeth and promote soft connective tissue regeneration.