Management of the primary dentition in vitamin D-resistant rickets

Vitamin D-resistant rickets (familial hypophosphatemia) is a systemic disease secondary to defective renal-tubular reabsorption of phosphate. The major oral manifestations are spontaneous abscesses in a caries-free dentition. Pulpotomies or extractions were frequently described in the dental literature as the therapies of choice. This article presents a new prophylactic approach utilizing zinc oxide--eugenol pulpectomies and full crown coverage in an attempt to retain the primary dentition and prevent abscess formation.     

Effects of synthetic muramyl dipeptide on bone metabolism in the fetal rat

Synthetic N-acetyl-muramyl-L-alanyl-D-isoglutamine (MDP) stimulated the release of 45Ca from fetal rat long bones in culture for 48 h and also increased the number of osteoclasts per bone and the number of nuclei per osteoclast. It also increased calcium uptake in enriched populations of osteoclasts obtained by sequential collagenase digestions of newborn rat calvaria. This effect was observed after a 120 min incubation with 10(-6) M MDP. Effects of MDP on calcium uptake in osteoblasts were not consistently observed. No effects on cyclic AMP were noted in either osteoclast or osteoblast populations treated with MDP for periods from 1-120 min at 37 degrees C.     

Clinical management of non-carious enamel defects

Enamel defects not caused by decay may occur singly or may be generalized over the entire tooth surface. In the past, treatment of these aesthetic problems required large cavity preparations or full crown coverage of the affected teeth. Now, with the advent of various resin restorative materials capable of bonding to enamel, new techniques are being developed which are less radical. By etching the surface of the enamel with varying concentrations of dilute phosphoric acid, sufficient porosity is produced to allow the resin to adhere to it. Thus, by removing a minimal amount of tooth structure, the affected area can be masked with a thin layer of resin material after the surface has been properly prepared. If the fault in the enamel is generalized, the whole surface of the tooth may be restored using this technique, effectively covering the tooth with an aesthetic veneer. The new resin filling materials offer good colour stability as well as resistance to abrasive wear. Tests have revealed that this mode of treatment has a successful retention rate of over 92 per cent after 5 years. Lightly discoloured or stained defects of the enamel may be treated by bleaching the affected area with no adverse effect on the pulp tissue. Those teeth not improved by bleaching can be conservatively managed by veneering their surfaces with smooth finishing plastic materials.     

The role of intracellular lysosomal enzymes in the autocellular-surveillance of unhydroxylated collagens in dermal and gingival fibroblasts

The turnover of unhydroxylated collagen was investigated in dermal and gingival fibroblasts derived from C57Bl/6J mice. Unhydroxylated collagen molecules were fostered by the inhibition of prolyl- and lysyl-hydroxylase by the addition of alpha, alpha' dipyridyl. Turnover of collagens was determined by single isotope continuous labeling, double-isotopic labeling, the use of lysosomal pH modulators, and proteinase inhibitors. These studies reveal that the turnover of unhydroxylated collagen is an extracellular event, in spite of the susceptibility of these abnormal structural and conformational proteins to proteolysis; the synthesizing cell does not utilize intracellular lysosomal enzymes as a means of modulating the quantities of non-helical unhydroxylated collagen as an intolerable post-translational error of protein processing.     

Murine model for analysis of the immune response to oral colonization

The overall aim of this work was to analyze the role of the immune response to a known periodontal pathogen, Actinomyces viscosus T14V, in orally superinfected Balb/c mice. The mice did not contain A. viscosus in the oral cavity prior to superinfection. Colonization by superinfecting A. viscosus was specific for the tooth surface.
When mice were placed on a soft, high-carbohydrate diet and superinfected with varying doses of A. viscosus T14VJ1, all mice became infected. A cell-mediated response to the bacteria was detected only in the low-dose inoculated animals, and only the low-dose mice developed bone loss. No serum antibody to the bacteria was detected in any animal. The response to the bacteria was detected in the cervical lymph nodes, which are the draining lymph nodes for the gingival tissue. The results suggest that the development of an immune response to the periodontal pathogen, A. viscosus T14V, correlated with bone loss in super-infected mice.     

A nonextraction approach to crowded dentitions in young children: early recognition and treatment

A total of 22 cases that were diagnosed as having space discrepancy problems in the deciduous and early mixed dentitions showed that treatment by early expansion therapy with Crozat appliances had eliminated the need for extraction of deciduous canines or permanent premolars.