Alveolar bone healing using a novel bone substitute material in a sheep tooth extraction model
Bone substitute materials placed into tooth sockets after tooth extraction may preserve alveolar bone. It is desirable that these materials be completely resorbed and replaced by patient’s own bone. Electrospun cottonwool-like nanocomposite (ECWN) is a novel synthetic bone substitute that incorporates amorphous tricalcium phosphate nanoparticles into a biodegradable synthetic copolymer poly(lactide-co-glycolide). This has shown encouraging results in a rabbit calvarial defect but has not been tested in a large animal model.Objectives: 1. To develop a tooth extraction socket model in sheep for bone graft research. 2. To compare ECWN and bovine-derived xenograft (BX) in this model.Methodology:Eighteen crossbred female sheep aged four to five years were used. Bilateral mandibular premolars were extracted atraumatically using Piezosurgery® unit. Second and third premolar sockets were grafted (Latin-square allocation) with BX, ECWN or left unfilled. Resorbable collagen membranes were placed over BX and selected ECWN grafted sockets and primary flap closure achieved. Two sheep were sacrificed at baseline and eight sheep each time after eight & 16 weeks. Resin-embedded undemineralised sections were examined for descriptive histology, histomorphometric and histometric analyses. Results:At eight weeks, healing was composed mostly of woven bone with no distinct differences among the different sites. At 16 weeks, osseous healing followed a fine finger-like trabecular pattern in ECWN sites. Non-grafted sites showed thick trabeculae separated by large areas of fibrous stroma. In BX grafted sites, residual graft material was encapsulated by newly formed bone or fibrous connective tissue. There were no statistically significant differences in bone formation across the four groups at eight or 16 weeks. However, ECWN sites had significantly less residual graft material than BX sites at 16 weeks (p = 0.048). There were significantly more hard tissue bridging formed in ECWN- sites when compared to B+ sites at 16 weeks (p = 0.024). Conclusion: This first description of a tooth extraction socket model in sheep supports the utility of this model for bone graft research. The results of this study suggested that the novel material ECWN did not impede bone ingrowth into sockets and showed evidence of material resorption. The present study also confirmed previous findings where new bone was formed to encapsulate BX particles.
Advisor: Duncan, Warwick John; Tawse-Smith, Andrew; Schmidlin, Patrick Roger
Degree Name: Doctor of Clinical Dentistry
Degree Discipline: Oral Sciences
Publisher: University of Otago
Keywords: Animal study; Biomaterials; Extraction socket; Implantology; Wound healing
Research Type: Thesis