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

Abstract

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.

Keywords: Amelogenin; apex formation; calcium hydroxide; pulp regeneration; regeneration.