I analyzed the length and frontal angle of the styloid process in panoramic radiographs of 429 patients seen at Osaka Dental University Hospital between 1991 and 2001. The cases were divided into three groups. Group 1, the control group, was 389 patients and included cases of dental disease, paranasal sinus disease, jaw arthritis and bone fractures. Group 2 was 36 patients and included those whose chief complaint was associated with the throat. Group 3 was four patients who were diagnosed as having an elongated styloid process.
The mean length of the styloid processes for group 1 was 30.08±4.69 mm. For group 2 the values were 40.50±5.61 mm, which was significantly longer than for group 1 (p<0.05). The length of the styloid process had no significant relationship with age, sex or side. The mean frontal angle of the styloid processes for group 1 was 67.65±5.41 degrees. For group 2 the values were 65.20±5.40 degrees, which was not significantly different from that of group 1. I was not able to determine the interior angle from panoramic radiographs. Shika Igaku (J Osaka Odontol Soc) 2002 Jun; 65(2): 165-180.

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Light-cured resin is often used in clinical orthodontics for bracket bonding. It is advantageous if this material releases fluoride to prevent dental caries during orthodontic treatment. We used Testskin (Toyobo, Osaka, Japan), which is a living skin equivalent, to examine the influence on cytotoxicity caused by differences in fluoride densities and light-curing conditions on fluoride-releasing resin.
We observed an increase in cytotoxicity in relation to increased amounts (0〜3.0%) of added NaF when using Kurasper F F-bond. This is thought to result from fluoride release and the effect of increased amounts of NaF on the permeability of the light into the resin. When applying irradiation with a plasma arc lamp for only 3-6 seconds, Kurasper F F-bond and Light Bond Sealant and Fuji Orth LC realized strong cytotoxicity, indicating that irradiation of at least 9 seconds is more desirable. Although fluoride releasing in orthodontic bonding resins is advantageous, cytotoxicity is a factor that must be considered. Shika Igaku (J Osaka Odontol Soc) 2002 Jun; 65(2): 181-188.

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Radiotherapy is used as a radical treatment for carcinomas of the naso- and oropharynx, with the intention of preserving shape and function of the dento-maxillo-facial region.
However, these patients often experience side effects such as xerostomia or osteoradionecrosis after receiving doses of 60 to 80 Gy.
We examined an importance of management of the oral environment for maintaining quality of life after radical irradiation of patients with carcinomas of the naso- and oropharynx.
From 1990 through 2001, we evaluated the oral environment of 35 patients with nasopharyngeal carcinomas and 36 with oropharyngeal carcinomas who had been treated with radiotherapy at other institutions. The evaluations were done at Osaka Dental University Hospital. The patients were divided into two groups based on whether the time after completion of radiotherapy was greater than one year before the first visit at our hospital. All subjects were examined for loss of teeth and changes in the index for decayed, missing and filled (DMF) teeth. There was little difference in the DMF index for patients with carcinomas of the oropharynx, compared with healthy adults of the same age. However, the DMF index one year after radiation therapy tended to increase compared with the controls.
We believe that oral hygiene instructions and monitoring of the oral condition should be done as soon as possible after radiotherapy for the patients with carcinomas of the naso- and oropharynx. It is also important that the location of the area irradiated is clearly understood in order to properly plan for the dental care of these patients. Shika Igaku (J Osaka Odontol Soc) 2002 Jun; 65(2): 189-195.

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We screened lecithinase production of Frevotella nigrescens and Prevotella intermedia strains isolated from periodontal pockets and periapical lesions to gain an understanding of the genetic basis of pathogenesis in P. intermedia/nigrescens. We found that 29 of 31 strains of P. nigrescens produced heavy precipitate on egg yolk agar, while 19 of 22 strains of P. intermedia did. We attempted to insert the EcoR Ⅰ -digested genomic DNA from the lecithinase-producing P. nigrescens strain 22 into Escherichia coil JM 109 for cloning relevant genes involved in the lecithinase production. However, E. coil did not result in the expression of lecithinase production. We carried out the suppression subtractive hybridization (SSH) between strain 22 and lecithinase non-producing P. nigrescens strain 42 in order to isolate DNA sequences specific for lecithinase-producing strain. However, we failed to get a subtraction library between these two strains. Therefore, we tried to isolate the lecithinase-negative mutants from strain 22 by ethidium bromide. We were able to isolate only one strain that did not produce lecithinase on egg yolk agar. This strain reduced exopolysaccharide (EPS) production concomitantly compared with the parent strain. These results indicate that, as a future strategy, we get appropriate materials (lecithinase⁺EPS⁺ parent strain, lecithinase⁺EPS⁺ mutant and lecithinase^-EPS^- mutant) for SSH to identify genes encoding virulence determinants in P. intermedia/nigrescens. Shika Igaku (J Osaka Odontol Soc) 2002 Jun; 65(2): 196-202.

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We investigated the prognosis for abutment teeth after placement of telescopic dentures. Using the chi-squared automatic interaction detector (CHAID), we analyzed 128 abutment teeth in 34 prostheses that had been placed in 28 patients.
We found that the survival rate of abutment teeth was low for 1) maxillary incisors during the first two years after placement of the prosthesis, 2) teeth that were adjacent to free-end defects during the first three to four years, and 3) teeth that were adjacent to free-end defects in Eichner's classification C and B4 cases during the first seven to nine years. Shika Igaku (J Osaka Odontol Soc) 2002 Jun; 65(2): 203-211.

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We evaluated the bond strength to enamel and dentin of two self-etching primer systems [UniFil Bond (GC) and Fluorobond (Shofu)]. Composite resins were bonded to polished enamel and dentin surfaces obtained from bovine teeth. Tensile bond strength was assessed at a cross head speed of 0.03 mm/min after 24h in 37℃ H_2O or after thermocycling 5000 times between 5℃ and 55℃ in H_2O. Although these systems exhibited good bond strength after 24 hours, the strength degraded after thermocycling,especially with enamel. This suggests that enamel etching is desirable with these systems.

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The evaluation of community oral health has been expressed quantitatively as the degree of caries incidence and periodontal disease. By using the oral age index,which we developed to evaluate an individuals level of oral health, it is possible to inform an individual of his oral health status. We attempted to determine if a diagnosis method for community oral health could be established using a linear relation between age and dental caries prevalence. We found that this method could be used to monitor the results of a national survey of oral health from 1987 to 1999. It was suggested that this method is useful for the diagnosis of community oral health.

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Dental services in the 21^st century must establish oral health based on function. Oral function, and especially the functional mastication, are important for quality of life. However, at present functional mastication has only been evaluated by objective methods or by examination focused only on the teeth, such as the teeth or the number of contact points. We attempted to determine the suitability of an examination method for functional mastication. We found that this method produced accurate results.

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