Abstract
The gubernacular foramen, a small orifice in the lingual wall of the deciduous canine alveolus, was examined macroscopically and histologically in crab-eating monkeys. The following results were obtained:
During the initial phase of the embryological period, the tooth germ was connected to the epithelium of the oral mucous membrane by a dental lamina. Following this, proliferating mesenchymal cells and fibers surrounding the canine tooth germ layer lingual to the deciduous tooth germ layer formed a bony capsule (bony crypt).
The gubernacular foramen of the deciduous canine which usually appears in the early phase of eruption occurred in the inside of the deciduous tooth alveolus. However, in this case, it appeared on the surface of the alveolar bone during the later phase of eruption with the canal being higher on the inner wall and lower on the outer wall. The foramen developed into two different types in a direction from the inner wall of the deciduous tooth alveolus to the alveolar margin (alveolar crest). The orifice of the foramen passed through the deciduous tooth alveolus and alveolar bone to form osteoblasts on the side of the periodontal membrane of the outer canal wall as high as the inner wall. It is possible that other foramen may open and osteoclasts in the deciduous tooth alveolus may make the inner wall higher than the outer wall. Just before the permanent canines erupted, the foramen grew larger and the canal became wider in diameter and shorter in length. A canine cusp tip could be observed. The inner layer of the gubernacular canal consisted of a dense network of connective tissue, including epithelial remnants of the dental lamina, while the outer layer consisted of a loose network of connective tissue and capillaries. The ratio of occurrence of the gu- bernacular foramina orifice was higher in the maxilla than in the mandible.
These results indicated that the canine gubernacular foramen migrated in a direction from the incisor towards the premolar gubernacular foramen. In addition, the gubernacular foramen and canal were also indicated to be the route for invasion of tooth germ and eruption of successional teeth.
