Concerning the innervation of the upper dentition in man
The primary objectives of this study were to determine: 1) the pathway of the superior alveolar nerves and their relation to the maxillary molar teeth in the fetal and neonatal specimens and in the child, and 2) whether nerve fibers entered any microscopically-observed tooth buds.
Materials and Methods. Three heads of 4, 69 and 7 months were appropriately fixed, decalcified, embedded in celloidin and serial sectioned in the frontal plane at 30, 60, and 120 u, respectively. Staining was with Hematoxylin and Triosin, Krichesky, periodic acid Schiff and Pearson's silver gelatin. The frontal sections were projected on to poster board at a 25X magnification and the positions of the infra orbital and superior alveolar nerves plotted. In the resulting sagittal graphic reconstructions the nerve fibers are seen to course to the dental sac of the first permanent and two primary molars. The anterior distribution was poorly defined. Two heads of 4 and 7 fetal months were sagittally sectioned and stained as controls. Nerve fibers could not be as accurately traced, but the morphologic pattern of the control and the graphic reproduction were in harmony. Three specimens at term dissected under a microscope displayed superior alveolar nerves extending to all primary teeth and first permanent molars.
To complement the results of the reconstructions and dissections, the nerve supply to the teeth of living children was investigated by means of nerve block technics. The maxillary first permanent and primary molars were opened with a dental bur under controlled conditions. If the patient expressed pain, the injection was given by means of a precise reproducible technic of depositing anesthetic s (.0 lution on the maxillary tuberosity. Sixty such injections were mad and the number of teeth anesthetized was recorded, and evaluated by the Chi square test. No injections were repeated. Some subjects received bilateral tuberosity injections.
Observations and discussion‘,. The results of these injections substantiated the observations made on the small number of anatomical specimens, and those cited in the literature. More than one pattern of innervation of these teeth is to be observed, and the innervation in the maxillae of an individual may be dissimilar. Furthermore, under the conditions of this investigation, the tuberosity injecti • is valuable technic for anesthetizing the first permanent molar and the second primary molar. The first primary molar is less frequently anesthetized.
All of the teeth examined in this study had nerve fibers reaching to their dental sac.