Mechanobiology of bone and suture - Results from a pig model.

Objective: To compare the morphology and mechanical function of sutures in normal pigs and minipigs to those of Yucatan minipigs, a natural model for midfacial hypoplasia.

Setting And Sample Population: Research took place at the Department of Orthodontics at the University of Washington and used varying sample sizes of normal-snouted pigs and Yucatan minipigs.

Material And Methods: Skulls and heads were examined for morphology of the nasofrontal suture using computed tomography and histology. Strain gauge recordings were made of sutural strain during mastication and during cyclic tensile loading of the nasofrontal suture.

Results: Sutures in Yucatans had narrower gaps than same-age normal pigs. The nasofrontal suture was simpler in construction and had more active osteoblasts on the bone fronts in Yucatans. The sutural ligament was less well organized, and based on a small sample, masticatory strain appeared to be lower than in normal minipigs. However, sutures were not fused and showed similar strains in response to the cyclic loading procedure.

Conclusion: Midfacial hypoplasia in Yucatan pigs has the likely proximate cause of hyperossification. Yet prior to fusion, the sutures appear to be amenable to treatment that would promote their growth rate.