The Journal of Nihon University School of Dentistry最新文献

The outermost surface cell layer of the developing embryo, the periderm, arises from the initial single layer of ectoderm and is eventually exfoliated from the stratified epidermis, which has the same ectodermal origin. In this study, monoclonal antibodies against chicken limb bud ectoderm were generated and screened for those which stained the periderm. Four separate antibodies termed PD2, 3, 7 and 9 were obtained from 180 mixed hybridomas. These PD antibodies stained the periderm selectively at all stages examined (stage 20-42). By correlating the results of immunohistochemistry with observations made by transmission electron microscopy, it was revealed that PD antibodies stained both the squamous periderm at an early stage and rounded bulging peridermal cells just before exfoliation. Therefore we feel that PD antibodies may be useful in further systematic investigations of the development and function of the chicken embryonic periderm.

A study was conducted to determine whether granules of type III glass-ionomer cement (currently used as a fast-setting lining material and fissure sealant) implanted immediately after tooth extraction interfere with the time course of alveolar wound healing. Histologic examination of the entire socket showed normal progression of the healing process. Progressive bone neoformation in parallel with a decrease in the volume fraction of connective tissue was quantified by a histometric method up to 6 weeks after tooth extraction. The presence of glass-ionomer granules in the cervical third led to a small delay in bone formation by the first week but not thereafter, as also observed in the remaining regions of the alveolus (middle and apical thirds) which tended, in contrast, to show a larger amount of trabecular bone from the third week onwards. These results show that the material does not hinder the wound healing process, and in fact favors bone neoformation.

A study was conducted to assess the measurement accuracy of a laser three-dimensional measurement system for measuring facial profile and to investigate the changes in lower facial morphology caused by experimental protrusion of the upper incisors, and also to examine the relationship between the changes in lip form and lip thickness. The study subjects were 24 Japanese male dental students attending Nihon University School of Dentistry at Matsudo, who had normal overbite, overjet, and normal occlusion, and a good facial profile. The mean age was 23.2 years with a range of 21.5 to 25.8 years. Three-dimensional measurements obtained by a computerized 3D laser scanning system were used to evaluate facial morphology. The measurement error of this system was less than 0.5 mm in any three-dimensional linear measurements. The stability and reproducibility of the recording procedure were evaluated. The changes in facial morphology caused by orthodontic treatment and orthognathic surgery were visualized in any direction by this three-dimensional graphic system. Lip thickness was not associated with changes in lip form. However, a relationship between the right and left corners of lip and lip thickness was noted. With regard to the ratio of changes in hard tissue and lips, the value of the original position for a 4 mm protrusion was not the same as that for a 4-8 mm protrusion. Also, the correlation of the changes in both groups was very low. The changes in lip thickness were associated with changes in stomion position, which in turn were related to the vertical change in the upper lip.

A study was conducted to investigate the timing relationship of temporomandibular joint (TMJ) sounds during mandibular movement, as evaluated by the location of the condyle, in relation to the articular fossa using axiograph recording. TMJ sounds during jaw opening and closing occurred over a wide range: opening sounds were observed within a range of 41-100% of maximum opening, while closing sounds occurred within 1-80% of maximum opening. In calculating the peak frequency of the joint sounds, it was noted that there was no correlation between the timing of the sound and its peak frequency. This study revealed that the acoustic characteristics of TMJ sounds may be unaffected by the location of the condyle.

The op/op mouse, which carries an osteopetrotic mutation, suffers from complete failure of tooth eruption. Commonly the teeth are ankylosed to the bone. Previous reports of ankylosis in the op/op mouse have been based on light microscopy. The aim of this study was to clarify the ultrastructural features of the ankylotic area using the oolong tea extract (OTE) staining technique. The ultrastructural features of ankylosis did not parallel the findings of light microscopy. OTE staining clearly stained the collagen fibers of bone and tooth, and the space dividing the tooth and bone was revealed by transmission electron microscopy. In comparison, light microscopy failed to reveal this space and the ankylosis was unclear. The true ankylotic area was smooth and the tooth was tightly ankylosed to the bone.

In our previous study carried out in 1994, we found 49 patients with unilateral cleft lip and palate (UCLP) among 51 patients with cleft lip and palate who visited the Department of Orthodontics, Nihon University Dental Hospital at Matsudo. In particular, patients with cross-bite (anterior cross-bite) UCLP were predominant, accounting for 21 individuals (41%). In the present study, we reviewed 79 patients with malocclusion including 21 with anterior cross-bite UCLP, who represent the largest subpopulation among patients with cleft lip and palate. These 21 patients were compared with other UCLP patients showing normal bite with regard to morphological differences evident in lateral roentgenographic cephalograms, to establish a proper policy of orthodontic diagnosis and treatment of their condition. The anterior cross-bite UCLP group showed differences in the skeletal pattern and the denture to skeletal pattern from the other patient groups except for the mesio-distal relationship. The anterior cross-bite UCLP group had cross-bite of the concave type, while the normal bite UCLP group had malocclusion of the convex type accompanied by maxillary overdevelopment. Thus, it is suggested that normalization of reversed occlusion leads to favorable growth of the upper jaw in UCLP patients with anterior cross-bite.

It is well known that interactions between microbial dental plaque and the host immune system play a major role in the etiopathogenesis of periodontal disease. The aim of the present study was to analyze the phenotypic properties of gingival T lymphocytes and subsets in patients with chronic inflammatory adult periodontitis (AP) showing various degrees of inflammation and to relate the results to the immunopathogenesis of AP. Gingival biopsies were obtained from patients aged between 26 and 52 yr who were grouped according to gingival index scores (GI) of 1, 2, and 3. Using immunohistochemical techniques, T cells (CD2+), T-helper cells (CD4+) and T-suppressor cells (CD8+) were identified in three well-defined areas of the biopsy samples. Moreover, peripheral blood was collected from the same patients, and relative counts of B cells (CD19+), HLA-DR+ cells and IL-2R+ cells as well as CD3+, CD4+, CD8+ cells were determined using three color flow cytometry. While the blood results were found to be within the normal ranges, the relative counts of CD4+ cells showed statistically significant decreases as the GI score increased. Similarly, the CD4+/CD8+ ratio also decreased. Moreover, gingival T lymphocyte and subset counts appeared to be related to the severity of gingival inflammation. Particularly, CD4+ cells showed a significant increase with the GI score. Furthermore, the CD4+/CD8+ ratio beneath the pocket epithelium was apparently correlated with increasing GI score (p < 0.05). The cytotoxic effect of CD8+ cells seems to be more prominent at the local level while the suppressor effect is more active systematically. This means that the price of systemic protection appears to be local destruction.

We report an application of the interval mapping technique using DNA pools of inbred mice. The latest challenge in molecular genetics is to use microsatellite markers for gene mapping and cloning. Little is known about the interval mapping technique for detecting candidate linkages in inbred mice. We investigated the optimum interval length of microsatellite markers for gene mapping using DNA pools on mouse chromosomes, and found that between 25 and 35 centi Morgans (cM) was sufficient. We estimated that at least two to four microsatellite markers required for interval mapping should be present on each chromosome. The number required would depend entirely on the linkage map.

We report an unusual case of pleomorphic adenoma with multifocal stromal bone formation, occurring in the upper lip of a 44-year-old Japanese woman. Islands of fibrous bone were in direct contact with stromal fibrocytes and parenchymal epithelial cells. A review of the literature revealed that stromal bone formation in pleomorphic adenoma of minor salivary gland origin is exceedingly rare.