Intro: Primary alveolar cleft repair treating congenital alveolar clefts with gingivoperiosteoplasty (GPP) has a 60% success rate. The remaining 40% have persistent alveolar bony defects requiring secondary grafting, which is associated with donor-site morbidity, graft resorption, and infection, and bone or tooth loss. Herein, we describe a novel critical-size defect GPP model using tissue-engineered scaffolds to improve bone regeneration and circumvent secondary grafting.
Methods: A 7x4x3-mm complete alveolar defect was surgically created in sixty 8-week old rats. Four scaffolds were tested within the defect: absorbable collagen sponge (ACS), ACS+BMP, hydroxyapatite-tricalcium phosphate (HA-TCP), HA-TCP+BMP, and no scaffold as control. Animals were sacrificed at post-operative weeks 4, 8, and 12. New bone was assessed histmorphometrically via micro CT. Decalcified sections were processed for histology.
Results: Morphometric analysis demonstrated regeneration in negative control groups to 43±10% at 4 weeks, but plateaued to 53±17% at 8 weeks and 48±6% at 12 weeks . ACS groups showed 50±12% at 4 weeks and 79±19% at 8 weeks and 69±12% at 12 weeks. ACS+BMP regeneration was 49±4% and 71±13%, and 66±13%, respectively. HA-TCP displayed 69±20% bone growth at 4 weeks and plateaued to 86±6% (p<0.05) at 8 weeks and 87±25% at 12 weeks, while adding BMP yielded 55±29%, 91±5% (p<0.05) and 90±1% (p<0.05) at 12 weeks. Histologically, HA-TCP groups stimulated appositional bone growth around scaffold granules. Four weeks showed activated osteoblasts, osteoprogenitor cells, and nascent bone along leading edges of bone spicules, while weeks 8 and 12 showed denser fibroblasts and maturing bone in the form of well-formed osteocytes.
Conclusions: HA-TCP shows greater osteogenic capability than ACS. BMP did not affect significant bone growth increases, perhaps due to lack of a sustained release system. The inherent osteoconductive properties of HA-TCP and its ability to provide for tissue guided regeneration (as opposed to an absorbable matrix) may have contributed to defect healing.