Dental precocity and secondary pneumatization

Abstract

Paranasal sinus expansion integrates skeletal elements of the nasal capsule, orbit, and dentition. Computer modeling suggests that sinus cavities appear in spatial "gaps" within the craniofacial complex. Anthropoid primates provide excellent natural experiments for testing this model, since not all possess a full complement of paranasal sinuses. Using histological and microCT methods, we studied an ontogenetic sample of Saguinus spp., which possesses maxillary sinuses (MS), and Saimiri sciureus, which does not form a MS. In Saguinus, secondary pneumatization begins perinatally. From infant to juvenile stages, the MS cavity progressively overlaps all of the deciduous molars (dm). The MS overlays all permanent molars in the adult. In Saimiri, the primordial space of the MS (maxillary recess) extends no farther posteriorly than dm2 at birth and no farther than the last premolar in the adult. Three‐dimensional reconstructions of newborns reveal critical differences that may account for these differences, including relatively larger dm teeth in Saimiri. Radiographic density of dm teeth is more than 20% greater in Saimiri compared to Saguinus, indicating more precocious development. These findings support the hypothesis that secondary pneumatization is a novel, opportunistic growth mechanism that may be constrained by adjacent elements such as the maxillary dentition. Grant support: NSF BCS‐0820751.