The dental pulp of rat mandibular incisors was examined to investigate the effects of streptozotocin-(STZ) induced diabetes on glycosaminoglycans (GAG) metabolism and on the activity of β-glycosidase (N-acetyl-β-glucosaminidase (NAG) and β-glucuronidase). GAG composition was determined by electrophoresis on cellulose acetate strips. The ratio of ΔDi-4S/ΔDi-6S was determined by the peaks from fluorescence high performance liquid chromatography. NAG and β-glucuronidase were investigated histochemically.
The results obtained were as follows :
1) Both the control and diabetic samples showed strong activity in the macrophages and weak, diffuse activity in the odontoblasts for both NAG and β-glucuronidase.
2) Although the amount of uronic acid in the dental pulps of diabetic rats decreased, the amounts of protein, hydroxyproline and DNA were similar to those of the controls.
3) GAG in the dental pulp consisted of sulfated-GAG, (chondroitin sulfate A or C, dermatan sulfate and heparan sulfate) and nonsulfated-GAG (hyaluronic acid) in both the controls and diabetic rats.
4) There were decreases in the amount of sulfated-GAG, especially chondroitin sulfate, with diabetes 5 days after STZ injection. However, the ratio of ΔDi-4S/ΔDi-6S in chondroitin sulfate remained similar to the controls.
These results show that insulin deficiency inhibits the synthetic pathways of GAG, mainly chondroitin sulfate. Therefore, it is suggested that this might interfere with calcification of the dentin.

View full abstract

The mechanism for salivary secretion is complicated because it is controlled not only by the autonomic nervous system but also by the high-level central nervous system, including emotions.
We assessed the effects of inhaled anesthetics (nitrous oxide, halothane, and enflurane) on salivary secretion in the rat submandibular gland under total spinal block (TSB) in order to eliminate the effect of the high-level central nervous system. At the same time we analyzed the effects of the neurotransmitters adrenalin and vasoactive intestinal polypeptide (VIP) in order to clarify the mechanism of salivary secretion. The distribution of VIP-positive fibers was also examined immunohistologically.
The following results were obtained.
1. Under TSB, nitrous oxide had no influence on salivary secretion.
2. Under TSB, halothane and enflurane inhibited secretion.
3. Adrenalin (3μg/kg) inhibited secretion and glandular blood flow. However, it had no effect under TSB.
4. Atropine would not block salivary secretion following administration of VIP (100μg/kg).
5. VIP-positive fibers were observed immunohistologically around the secretory ducts and acini.

View full abstract

In order to construct standardized charts for root resorption in the primary dentition of Japanese children, we investigated the stages of resorption (1/4, 1/2 and 3/4 of the root) based on the criterion of Fanning, et al. using 11,167 panoramic radiographs (5,759 of boys and 5,408 of girls). The following information was obtained.
1) The root resorption for a tooth on one side was the same as for its counterpart on the other side regardless of differences in sex or arch.
2) The average age for each root resorption stage was lower in girls than in boys regardless of differences in sex or arch.
3) The average age for each root resorption stage was lower in the mandible than in the maxilla for every tooth.
4) In the maxilla, the period between 1/4 to 3/4 resorption of the tooth was greater in the primary molars than in the primary anterior teeth. However, the opposite was true in the mandible.
5) Although no difference was observed between the maxilla and the mandible in the resorption period for the primary incisors and canines, the resorption time for the primary molars was greater in the maxilla than in the mandible.
6) When the relationship was observed between the resorption stages for each tooth and the calcification stages for the corresponding successional permanent tooth :
a) With the exception of the maxillary and mandibular canines, the average age for 1/4 resorption of the primary root corresponded to the period between completion of the permanent crown and initial root formation of the successional permanent tooth.
b) With the exception of the maxillary and mandibular canines, and the mandibular second permolars, the average age for 3/4 resorption of the primary root corresponded to the period between 1/4 and 1/2 formation of the root of the successionalpermanent tooth.
From these results, standardized charts were constructed for the resorption of the roots of primary teeth in Japanese children. These standardized charts are useful in daily clinical practice in such areas as endodontic treatment of primary teeth and orthodontics.

View full abstract

[in Japanese]

View full abstract