In order to effectively restore the teeth which lost their supragingival tooth structure, 1) the difference in the two types of core and dowel: cast dowels and prefabricated post with composite resin, 2) the effectiveness of different cements: zinc phosphate cement, adhesive resin cement without and with 2 types of acid treatment, and 3) the effectiveness of retentive pins were observed in this study. Full coverage cast crowns were made and cemented with zinc phosphate cement to each sample. Compressive force of 10 kg was applied 1, 000 times against the lingual surface of each sample, while the junction of the crown and tooth was saturated with India ink. Later, the degree of filtration of the ink was examined. Results: When both fabricating methods were compared, a smaller filtration was observed in the case of cast post and core. For the cementing method, the use of adhesive resin cement with phosphoric acid treatment showed the smallest filtration. The pins also showed effectiveness. From this experiment, cast dowels cemented with adhesive resin cement after etching with 40% phosphoric acid showed the best results as the core preceding the final full coverage restorations for the teeth that have lost their coronal structure.
The purpose of this study was to evaluate the dento-craniofacial morphology and the occlusal characteristics in the Peruvian Indians from the dental-anthropological point of view. The sample consisted of cephalograms, pantomograms, dental casts, photos and records (anthropometric measurements and oral examinations) which were taken from 145 modern Peruvian Indians and 185 ancient Peruvian Indians. The results were summarized as follows: 1. About the dento-craniofacial morphology, the modern Peruvian Indians showed; 1) brachycephaly and large bi-gonial breadth, having the similar tendency as the Japanese. 2) smaller facial height and shorter depth of the cranial base and jaws than those of the Caucasians. 3) small gonial angle and small mandibular plane angle which were specific characteristics compared with the Japanese. 4) shorter depth of the alveolar portion of the jaws, larger anterior facial height and larger gonial angle than those of the ancient Peruvian Indians. 2. About the occlusal characteristics, the modern Peruvian Indians had; 1) wider dental arches than that of the Caucasians, showing the same values as the Japanese. 2) remarkable differences in the mesiodistal crown diameters in all of the teeth and in the length of the dental arch between the early and late permanent dentition, which were caused by the mesial shifting of the teeth because of the attrition in the horizontal dimension. 3) smaller incisors, larger premolars and molars in the mesiodistal crown diameter than those of the Caucasians and also had smaller incisors and premolars compared with the Japanese. 4) smaller teeth in the mesiodistal crown diameter in all of the teeth than that of the ancient Peruvian Indians. 5) shovel-shaped incisors in a higher frequency compared with the Caucasians and also had an interstitial tuberculum on the upper premolars in a lower frequency and underdeveloped crown on the lower premolars.
The purpose of the present study was to investigate the changes of response properties in the nerve fibers innervating the cat lower canine tooth pulp under a pathophysiological condition. In order to damage the pulp tissues, noxious heat and arsenic acid were used as stimuli of high intensity. The results obtained were as follows: 1. The nerve fibers were initially sensitized and subsequently desensitized. In the early stage, the electrical thresholds were lowered and some of the tooth pulp nerves showed spontaneous activities and also repetitive firings to a single electrical stimulus. In the later stage, their electrical thresholds were gradually elevated and some of them failed to respond to the electrical stimulation. Additionally, few of them further responded to dentin probing. 2. The changes of the responses in the fast conducting fibers, which were myelinated, were observed earlier than in the slowly conducting ones, many of which were unmyelinated, It was speculated that the initial changes occurred in the terminal endings of the myelinated fibers which are thought to be the receptive sites for the mechanical stimulation in the pulp. 3. These changes were almost the same in both types of stimuli. These results suggest that the pulp nerve fibers are sensitized when intense stimuli are given to the dentin and that the myelinated fibers may mainly conduct pain information to the central nervous system in the early stage of pulpal injury. Subsequently, prolonged intense stimuli may alter the normal pulpal tissues into pathophysiological ones, resulting in the deterioration of the function of the myelinated fibers. Contrarily, unmyelinated fibers may maintain their functions and predominantly conduct pain information even in that condition.
Osteogenic potential of the HOS cells, a cell line derived from the human osteosarcoma, and KHOS cells, HOS cells transformed by the Kirsten murine sarcoma virus, was studied biochemically and histochemically by analyzing the expression of two osteogenic differentiation markers of the bone cells. Both the expression of the liver/bone/kidney-type ALPase and deposition of calcium were observed in the HOS cells, while the expression of both differentiation markers were suppressed in the KHOS cells. Southern and Northern blot analyses suggested that in the KHOS cells a single copy of the intact K-MSV proviral DNA was integrated and the 6.5 kb K-MSV RNA was transcribed from the integrated DNA. The expression of the K-MSV genome in the KHOS cells is discussed in relation to the suppression of the expression of osteogenic differentiation markers.
In cleft lip and palate patients, a scar tissue after surgical operation causes several difficulties on orthodontic treatment. The purpose of this paper is to clarify the biochemical characteristics of cultured myofibroblasts isolated from experimental scar tissue in rat palatal mucoperiosteum, compared with those of normal fibroblasts in palatal mucoperiosteum and smooth muscle cells in thoracic artery. Myofibroblasts in the stationary phase were more aggrigative than fibroblasts. Both the capacity of retracting collagen lattices and the amount of actin filaments of Triton-insoluble cytoskeleton were higher in myofibroblasts than those in fibroblasts. The amount of collagen synthesized and the ratio of type III to I collagen was higher in myofibroblasts. Prostaglandins biosynthesized from [14C] arachidonic acid in myofibroblasts and fibroblasts were prostaglandin D2i E2 and F2α, and the activitiy of producing each prostaglandin was not significantly different between both cells, whereas smooth muscle cells produced mainly prostaglandin 12. In myofibroblasts, the effect of some drugs (bradykinin, 5-hydroxytryptamine and prostaglandin F2α) to release arachidonic acid and prostaglandin E2 was lower than that in fibroblasts, being similar to that in smooth muscle cells. Myofibroblasts cultured in this study reflected the chracteristic features of scar tissue from which those were isolated.
Mammalian facial development involves formation of nasal placode (NP), its invagination and protrusion of facial prominences, and consequently fusion of them. These processes have some similarities to neurulation and other organogeneses, in which contraction of actin filaments at the apical site has been shown to be possible morphogenetic force. The purpose of this study is to examine the role of actin filaments in developing nasal epithelium (NE) . C57BL/6 mouse embryos sacrificed on 8.5 to 11.5 days of gestation (plug day=0) were fixed in 4% PFA in PBS. 57, um of frozen sections were stained with rhodamine-phalloidin (R-P) . Before formation of NP, there was no specific localization of F-actin. When NP was formed, F-actin was observed at the apical site of the placode and also of the invaginating NE. On the contrary, it was localized at the basal site of the epithelium of developing nasal protrusions. Mouse embryos were exposed to 0.15g/ml of cytochalasin D (CD) for 2 hours in vitro using whole embryo culture system. Facial malformation was observed in 70.40 of the CD-treated embryos at the end point of the culture for 24 hours. The distribution of F-actin in NE was observed to be partially broken in R-P staining image just after the treatment. These findings suggested that F-actin in NE may play a critical role in mouse facial formation.