A tumor-like foreign body in the maxillary sinus is reported. Examination of the paranasal sinuses by computerized tomography revealed a dense and well defined lesion equal to that of bone in the left maxillary sinus. After surgery, the lesion was found to be alginate used for impression-taking before fitting of a prosthesis, and not a tumor.
Dense particles of hydroxyapatite (HAP) were consolidated in the frontal sinus of dogs, and bone formation with time was observed in undecalcified ground sections using Cole's HE stain. In the HAP mass on the experimental side, a small amount of newly generated bone was seen around the inner wall of the sinus after 3 months. Even after 12 months, bone formation was still limited to the surrounding region and did not extend to the central region of the sinus. In the sinus opened area, bone formation was seen from both ends of the bone along the HAP particles, and ossiferous closing was observed without leaving a recess at 12 months. On the control side, yellow bone marrow tissue, pneumatic spaces or cyst formation were seen, and a recess was left in the sinus opened area in all cases.
High-strength denture teeth (HS teeth) were developed in order to improve the hardness and wear resistance of conventional plastic denture teeth (PL teeth), while retaining their feature of easy occlusal adjustment. The objective of this study was to evaluate the abrasive wear resistance of HS teeth. We conducted wear tests and measured surface roughness using six types of anterior artificial teeth, i.e., three types of HS teeth and three types of PL teeth, the latter serving as the control. The results of the toothbrush abrasion test revealed that the HS teeth had about 5 times greater wear resistance than the PL teeth. It was also found that the type of artificial teeth and the number of abrasive wear-testing strokes had a significant (P<0.05) influence on the surface roughness of artificial teeth.
Morphological differentiation of the distal ends of ameloblasts (AMs) from the late presecretory to early secretory zones of the rat upper incisor was studied by electron microscopy. Preameloblasts (PAs) showed a high columnar shape, with the nucleus located in the basal portion. The Golgi apparatus occupied the supranuclear region with type-1 vesicles, and microvilli were present at the distal cell membrane. Coarse-textured material was observed inside the type-1 vesicles and in the lateral intercellular spaces as well as along the distal cell membrane, whereas fine-textured material was found along the distal cell membrane. Near the region of initial enamel formation, large matrix islands were found in the lateral intercellular space. A thin electron-dense layer was observed on the dentin surface. This layer might have occurred as a result of diffusion after degradation of the coarse-or fine-textured material into a finer substance in the extracellular spaces. In the region of initial enamel formation, the distal cell membrane of AMs was flat, but shallow and narrow membrane invaginations were associated with the cell membrane close to the matrix islands. In the region of inner enamel formation, a cone-shaped Tomes' process was formed between large matrix islands which had developed in the intercellular spaces between the lateral portions of the distal ends of AMs. It was considered that the membrane invaginations which had existed at the distal end of PAs moved lower toward the distal terminal bar, thereafter becoming microvilli.
A small ameloblastoma located in the alveolar bone of a 34-year-old male is presented. Clinical examination revealed slight swelling of the alveolar bone between the lower second premolar and first molar areas with bone-like hardness, and radiographic examination showed a well circumscribed radiolucent lesion surrounded by a thin radiopaque layer, within which was contained the root of the second premolar tooth. Histopathologically, the lesion was compatible with a diagnosis of follicular ameloblastoma. A review of the literature yielded only four cases of small ameloblastoma located in the alveolar bone. These four previously reported cases and the present case strongly suggest that a small ameloblastoma located in the alveolar bone of adults arises from Malassez's epithelial rests scattered in the periodontal membrane.
A cross-sectional survey involving 303 6-15-year-old aboriginal children was carried out in Selangor, West Malaysia. Dental caries status was assessed on the basis of the methods of the World Health Organization Oral Health Survey. The findings indicated a generally low prevalence of dental caries with a mean df of 4.94 for children below the age of 10 years. Mean DMFT and DMFS values of 1.71 and 3.22, respectively, were also observed for the 6-15-year-old children.
A study was conducted to evaluate using SEM the earliest events of initial blood clot formation on periodontally diseased root surfaces given various treatments. Six teeth with periodontal disease were extracted from six different subjects and were studied in two individual groups. In the first group the root surfaces were divided into three individual treatment areas : (a) intact periodontal ligament, (b) planed, (c) planed and also treated with 1% citric acid. The root surfaces in the second group were likewise divided into three treatment areas : (a) intact periodontal ligament, (b) planed, (c) planed and topically conditioned with tetracycline HCl. All the roots were reinserted into the original extraction sites, and then removed at either “zero” (less than 5 s), one or 3 min and prepared for SEM evaluation. It was observed that organized clot formation occurred more rapidly in the treatment areas where both root planing and topical conditioning with tetracycline HCl had been done.
A smear layer is formed after cavity or root canal preparation. The aim of the present study was to reinforce the dental surface in order to prevent the invasion of foreign irritants, by treating the smear layer with fluoride. Dentinal samples whose surfaces had been washed with water after the formation of a smear layer, and corresponding samples without washing, were examined by the dye penetration test, and the results were compared. Although there was no significant difference between the two groups of samples, dye penetration was suppressed by about 30% in washed samples, whereas the suppression was 20% in unwashed samples. When washed samples were treated with 1.0% SnF2, 10.0% SnF2, 7.5% Na2PO2F, 15% Na2PO2F, APF, 10 mM In (NO3) 3, 100 mM TiF3, 50 mM TiF3, or 10 mM TiF3, samples washed after treatment with 1.0% SnF2 showed a dye penetration suppression of about 60% as a whole, in comparison with samples having no smear layer. Hardly any suppression of dye penetration was observed after treatment with other fluorides.