Occlusal Relief and Dental Wear Predict Pulp Chamber Volume in Captive Baboons

Primates have adaptations that mitigate the functional consequences of dental wear. One such adaptation is dentin deposition within the pulp chamber, which may extend tooth functionality. Because this deposition can reflect age-related secondary dentin and stimulus-driven tertiary dentin, it remains unclear whether the resulting pulp volume reduction primarily tracks cumulative wear, chronological age, or aspects of occlusal morphology. Here, we test covariation among pulp chamber volume, dental wear, and dental topography in captive baboons. MicroCT and occlusal scans were used to evaluate relationships among pulp volume, dental wear, and dental topography for M₁-M₃ from 46 adult baboons that were part of the Southwest National Primate Research Center. Ages of death were adjusted for molar eruption timing to calculate "wear age," representing the duration each tooth was in occlusion. Wear age was positively correlated with dental wear metrics and showed weaker relationships with dental topography. Corrected pulp volume was negatively associated with wear age, dentin exposure ratio, and Krueger-Scott scores, while relief index (RFI) was the only dental-topography measure associated with pulp volume across molars. These results suggest that pulp chamber reduction in baboons reflects both cumulative wear and the functional effects of occlusal morphology. Because RFI in worn teeth reflects wear-related changes in crown geometry, we hypothesize that variation in occlusal relief may also relate to differences in how mechanical loads are distributed across the crown. These proposed relationships remain to be tested directly. Patterns of pulp chamber remodeling may therefore vary across taxa with dental morphology and loading environment.