Maxillary tooth growth in the adult male babirusa (genus Babyrousa).

The growth of the maxillary canine teeth of the babirusa (genus Babyrousa) was studied on a sample of 149 adult male babirusa skulls from twenty-two international museum and private collections. Skulls from Buru, Sulawesi and the Togian Islands were represented. The continuous growth process was summarised into five stages ('A'-'E') according to the position of the tip of the tooth over the bones of the skull. The supracutaneous portion of the tooth grew in a curve-linear fashion dorso-caudally, and was orientated such that the tips grew towards the midline of the cranium. The teeth of Sulawesi and Togian babirusa grew more dorsally over the nasal and frontal bones. Measurements were made on a subset of 45 teeth from Sulawesi babirusa skulls. The subcutaneous portion of the maxillary canine tooth (n=22) increased in size from 37.3mm (95% CI: 29.9-44.4mm) in growth stage 'B' to 54.3mm (49.4-59.2mm) in growth stage 'E' as the erupted portion of the tooth (n=19) lengthened from 81.3mm (43.8-118.9mm) in growth stage 'A' to 215.3mm (177.8-252.9mm) in growth stage 'E'. The apical end of the tooth was open and thin-walled. The lumen of the tooth was filled with a cone of well vascularised dental pulp that extended almost to the tip of the tooth. The angle of curvature of the tooth within the alveolus (n=22) decreased from 19.8 (17.3-22.3) degrees in growth stage 'B' to 7.4 (5.7-9.0) degrees in growth stage 'E'. The corresponding supracutaneous angle of curvature (n=25) reduced from 36.8 (33.6-40.1) degrees in growth stage 'A' to 10.7 (8.6-12.8) degrees in growth stage 'E'.