Successful periodontal healing has been demonstrated in animals following application of citric acid to exposed root surface. However, we have been unable to achieve comparable results on clinical patients. Accordingly, the present study, using monkeys, was designed to re-evaluate the degree of interdigitation of newly-formed gingival fibrils with ones exposed to citric acid compared to normal attachment tissues of the retained periodontal ligament. We found that superficial collagen fibrils in both cases suffer degradation following normal inflammation and healing secondary to flap surgery. On retained periodontal ligament tissues, this change was limited to superficial levels and newly-formed collagen fibrils were linked immediately with old ones. In contrast, when exposed collagen fibrils were conditioned by exposure to citric acid, the degradative change occurred more deeply, and healing was delayed. Thus, the citric acid may not be the best choice of root treatments in terms of promoting better gingival tissue attachment. Furthermore, the results indicated that fibrils preserved on the root should not be curetted as possible during flap surgery as they offer an improved chance for optimal reattachment.
The periodontal tissue of beige mice has been examined by electron microscopy. Specimens of the periodontal tissue from the right mandibular first molars of 10 male beige (bg/bg) and 5 male non-beige (bg/+, controls) mice, were fixed in a mixture of glutaraldehyde and paraformaldehyde, and then decalcified in EDTA. After fixation in osmium tetroxide, the specimens were dehydrated and embedded in epon resin. Ultrathin sections were then stained with uranyl acetate and lead citrate, and observed by electron microscopy. A larger number of cytoplasmic crystalloids were seen in the lysosomes of the histiocytes of the beige mice than in the non-beige mice. These cytoplasmic crystalloids showed striation structures composed of linear densities that were oriented longitudinally, transversely, and obliquely, with about a 4-nm pericdicity. The periodontal tissue of the beige mice contained several cells with numerous cytoplasmic crystalloids, whereas there were few cells with fewer crystalloids in the non-beige mice.
We recorded intercuspal occlusal contacts using silicone for 20 subjects with complete dentition maintaining their masseter muscle contraction levels at 10 and 30% of maximum EMG activity. A computer-aided video system was used to read the silicone image and translate the intensity of transmitted light to the thickness corresponding to the distance between opposing teeth. The intraocclusal distance was greater in the anterior than in the posterior teeth. The intraocclusal distance in the canines was intermediate between that in the incisors and posterior teeth. Although these tendencies were the same at the 10 and 30% EMG levels, an increase in the EMG level decreased all the distances.
Alteration of cell-associated heparan sulfate proteoglycan (HSPG) under tumor-bearing conditions was evaluated using microsomal membranes prepared from the liver of ascites Tawa sarcoma-bearing and age-matched control rats. Cell-associated HSPGs have been fractionated into two populations displaying different modes of membrane association; one is a NaCl-soluble HSPG and the other is recovered only after detergent treatment of the membranes. The former is thought to represent HSPG from the peripheral membrane and the latter, HSPG from the intercalated membrane. We extracted the cell-associated HSPGs from liver microsomal membranes with a NaCl solution followed by a deoxycholate (DCA) solution. Both were isolated by gel filtration and cetylpyridinium chloride precipitation. Glycosaminoglycans (GAGs) were isolated from the tumor cells and tumorous ascitic fluids by standard procedures. Using electrophoresis on a cellulose acetate membrane, it was confirmed that the cell-associated HSPGs contained no GAG chains other than HS, and that these HSPGs did not include PGs from tumor cells since hyaluronic acid predominates in tumor cells while chondroitin sulfate is present in ascitic fluids. The HSPG extracted with the DCA solution was markedly reduced under tumor-bearing conditions, with slight increase in the NaCl-soluble HSPG. The results suggests that this condition strongly influences the type of cell-associated HSPG related to thc intracellular cytoskeleton.