The frequencies of oro-maxillo-facial tumors, by type, seen at the Guangxi Medical College Hospital were surveyed in order to compare different regions of the People's Republic of China. Computer analysis was performed on data for all oro-maxillo-facial tumors, as confirmed by the hospital between 1957 and 1987, inclusive. The results were then used in a comparative study with those of five other medical colleges. Among a total of 4, 052 cases, there were 1, 593 benign tumors, 2, 049 malignant tumors and 410 unknown tumors. Tumors derived from the epithelium were the most common type (42.0 % of the total), whereas in the other five medical colleges the mean corresponding proportion was 27.8 %, the difference being significant (p < 0.05). Epithelial tumors were also the most common type of malignant tumor (70.5 % of the total), whereas the corresponding proportion reported by the other five institutions was 60.6 %, which was also significantly different (p < 0.05). The proportion of malignant tumors among the total was more than 50.6 %, which was higher than that reported by the other five colleges. This study shows that epithelium-derived tumors and malignant tumors were encountered more frequently at Guangxi Medical College than at the other five medical colleges in China. (J. Oral Sci. 42, 57-62, 2000)

View full abstract

A temporary filling should seal the endodontic access cavity to avoid reinfection of the root canal system during endodontic treatment. The aim of this study was to evaluate the marginal seal of four temporary filling materials in endodontic access cavities in vitro, using the dye penetration method. Endodontic access cavity preparations were in 50 incisor and 50 molar noncarious nonrestored crowns of extracted human teeth. The coronal access of 10 teeth per group were filled with Coltosol, Algenol, IRM, Fermit or Fermit-N. After storing the teeth in demineralized water for 48 hours, they were immersed in 2 % methylene blue dye for 24 hours. All the teeth were sectioned longitudinally and the linear depth of dye penetration was evaluated under a stereomicroscope. There was no significant difference in the microleakage observed in the high elasticity light-cured resin composite (Fermit) versus the low elasticity light-cured resin composite (Fermit-N) groups (p > 0.05). (J. Oral Sci. 42, 63-67, 2000)

View full abstract

This study evaluated the pulpal responses induced by application of two types of bonding system to the exposed dental pulp. One consisted of the following steps : etching with neutralized EDTA, application of an experimental water-based photocuring bonding agent, and restoration with a commercially available photocuring resin composite (EDTA etching system). The other was treatment with an experimental water-based self-etching primer, application of a commercially available bonding agent, and restoration with a commercially available photocuring resin composite (self-etching system). These two systems of treatment were applied to the exposed pulp. Calcium hydroxide was used as a control for the direct pulpcapping material. The pulps in class V cavities in the anterior teeth of beagles were mechanically exposed and then filled using the etching, the self-etching, or the Ca (OH)₂ system. The beagles were sacrificed on the 7th, 30th or 90th postoperative day, and pulpal responses were investigated histopathologically using light microscopy. The EDTA etching system induced severe pulp reactions at 7 days after the operation. These reactions did not completely diminish after 90 days. Reparative dentin formation was observed at day 90. The self-etching system showed moderate pulp reactions, which gradually decreased over the experimental period. Reparative dentin bridge formation was observed at day 90. No necrosis of the pulp was observed at any time. Calcium hydroxide induced both moderate and severe initial pulp reactions, with reparative dentin formation evident at day 30. Necrosis was observed in the superficial pulp. It is suggested that the EDTA etching agent caused not only pulpal damage but also re-bleeding because of rinsing and drying. The self-etching system is a promising system for direct pulp capping. (J. Oral Sci. 42, 69-74, 2000)

View full abstract

Lotka's law of scientific productivity is a bibliometric example : the number of authors against the number of contributions made by the authors was plotted on a logarithmic scale. The points were closely scattered around a straight line having a slope of-2. The purpose of this study was to apply information technology to real-world data and to quantify the extent of the bibliometric regularity that exists in the literature of dental science. We have analyzed the productivity index of authors (PI) in a scientific journal (Journal of American Dental Association). Details of a total of 4, 088 papers published between 1966 and 1995 were extracted electronically from MEDLINE. The total number of authors was 5, 589, responsible for 8, 569 authorships. Only 0.8 % of the authors presented a PI >= 1 (large producers), and 78.1 % a PI = 0 (occasional authors). The number of authors publishing N papers was 1/N^2.64 of those publishing one paper. The result suggested that repeated publications in the Journal were more difficult than those predicted by Lotka (1 / N ²). (J. Oral Sci. 42, 75-78, 2000)

View full abstract

The aim of this study was to investigate the relationship between tooth-brushing angle and efficacy of plaque removal. The subjects in this study were 72 students (18-21 yrs.) from paramedical schools. They answered the questionnaire of the Hiroshima University - Dental Behavioral Inventory (HU-DBI) to assess dental health behavior, and then received examinations of tooth-brushing angle, efficacy of plaque removal and gingival condition. The examination sites of tooth-brushing angle and the efficacy of plaque removal were the lingual surfaces of the posterior teeth in the mandible. The tooth-brushing angle, efficacy of plaque removal, gingival condition and dental health behavior were significantly associated with each other. The subjects who directed the bristles of the toothbrush vertically toward the tooth surfaces had a high efficacy of plaque removal, good gingival condition and good dental health behavior. Thus, it is important to direct the bristles vertically toward the tooth surfaces for effective plaque removal. In addition, knowledge related to good dental health might be necessary to carry out effective tooth brushing. (J. Oral Sci. 42, 79-82, 2000)

View full abstract

Cannulation procedures have shown thatα-amylase is produced primarily by the parotid gland, whereas lysozyme is produced mainly by the submandibular and sublingual glands. In this study, the ratio of lysozyme to a-amylase was determined in whole human saliva following challenge with various gustatory and mechanical stimuli. Comparison of this ratio with the immediately preceding “baseline” value, and knowledge of the salivary glandular origin of these enzymes, gives an indication of the level of activation of these differing glands. This methodology obviates the need for invasive cannulation techniques. The findings also show that strong taste stimuli, such as salt, activate the submandibular/sublingual glands more as compared to the parotid gland. (J. Oral Sci. 42, 83-86, 2000)

View full abstract

The distribution of glycoconjugates in normal maxillary sinus tissues, in cases of maxillary sinusitis and in postoperative maxillary cysts (POMC), was examined using seven different lectins as probes. The results showed that wheatgerm agglutinin (WGA), peanut agglutinin (PNA), Ulex europaeus agglutininl (UEA-1), Ricinus communis agglutinin-1 (RCA-1), and concanavalin A (ConA) strongly react with the cilia and goblet cells. The binding of WGA, PNA, UEA-1, and RCA-1 was increased in maxillary sinusitis and POMC compared with normal maxillary sinus epithelium, whereas that of ConA was decreased. The decreased binding of ConA suggested that there were fewer mannoside residues in the maxillary sinus epithelium in the inflammatory lesion. The PNA bound to the cilia, goblet cells and mucous glandular cells in maxillary sinusitis and POMC, but not in normal, uninflamed cells, indicating that D-galactose was produced by the inflammatory condition. Similar binding patterns of PNA and RCA-1 were found in the cilia and on the surface of the epithelium and in the goblet cells. It is assumed that the carbohydrate moiety in the sinus mucosa is altered in inflammatory conditions. (J. Oral Sci. 42, 87-91, 2000)

View full abstract

The shape of the mandible is used by orthodontists as an aid to orthodontic treatment planning, with different shapes displaying different growth characteristics and being associated with different functional patterns. However, the quantification of shape using conventional linear and angular variables does not always include details of some of the more subtle aspects of form. Fourier analysis enables accurate representation, with few coefficients, of a mandibular outer line from articulare to infradentale. The aim of this study was to investigate, using a cluster analysis, the relationship between variation in mandibular form and overall facial morphology. A cluster analysis of the Fourier amplitudes classified mandibular forms into one of seven groups for both males and females. The cluster analysis showed that the gonial angle and the inclination of lower incisor were associated with facial type according to the mandibular variables. Furthermore, the Fourier descriptions of mandibular form could be related to the observed variation in facial form, each of the clusters based on mandibular form being associated with demonstrable differences in dentofacial morphology. (J. Oral Sci. 42, 93-100, 2000)

View full abstract

To clarify whether fibroblasts could be involved in the pathogenesis of periodontal pocket formation, the chemotactic activity of radicular cystderived fibroblast-like cell (RCF) -conditioned medium (RCF-CM) for gingival epithelial cells was examined using a modified Boyden chamber assay. RCF-CM possessed significant chemotactic activity, which was decreased markedly by treatment with anti-human hepatocyte growth factor (HGF) antibody. Furthermore, the chemotactic activity of RCF-CM was well correlated with HGF content. These results show that the RCF secrete an HGF-like factor, and suggest that such a factor derived from periodontal fibroblasts might play a role in epithelial apical migration in periodontitis. (J. Oral Sci. 42, 101-106, 2000)

View full abstract

Soft tissue myxoma of the oral cavity is extremely rare. We present a case of soft tissue myxoma arising from a mandibular anterior gingiva in a 51-year-old male patient. Histological examination showed islands of odontogenic epithelium scattered in the mucinous stroma. This lesion was supposed to have a odontogenic origin. The clinical differences between soft tissue myxoma with bone destruction and those without bone destruction are also discussed by a review of the literature. (J. Oral Sci. 42, 107-109, 2000)

View full abstract