Endodontic regeneration and tooth revitalization in immature infected sheep teeth

Aim To examine the response of immature sheep teeth with infected root canal systems to a commonly used pulp regeneration/revitalization protocol. Methodology Immature mandibular right first incisors in four sheep were mechanically exposed and the pulps infected. The mandibular left first incisors remained intact as controls. Five weeks later, the experimental root canals were chemo-mechanically cleaned and dressed with a triple-antibiotic paste for 4 weeks, before bleeding was induced inside the canal by mechanically irritating the periapical tissues. A collagen dressing was packed coronally onto the blood clot and the canal orifice sealed with mineral trioxide aggregate and glass ionomer cement. Six months later, the mandibles were collected and the teeth with associated periapical tissues were analysed radiographically, with CT scanning, and by histology. The changes in root length, dentine thickness in the apical third (mesially and distally), and apical diameter were analysed using Student's t-test. Results Radiographs revealed significant increases in root length, root wall thickness and narrowing of the apical diameter of the canals after treatment (P < 0.05), with no significant differences in root diameters found between the experimental and the control teeth (P > 0.05) on both radiographic and CT results. Root maturation and thickening of the walls due to hard tissue deposition was confirmed by histology in all experimental teeth. Hard tissues in the apical portion of the root were more developed than in the coronal portion. Conclusion Endodontic regeneration and tooth revitalization procedures in immature infected sheep teeth showed positive outcomes with similar increases in root length and development to the control teeth.