Immunohistological study with peroxidase-antiperoxidase staining in a case of generalized prepubertal periodontitis

A case of prepubertal periodontitis was observed and examined immunohistologically with peroxidase-antiperoxidase staining. The patient was an 11-year and 7-month-old Japanese girl, well-developed and well-nourished. Her parents were first cousins. Her chief complaint was the loosening and loss of the permanent teeth. There was a similar history of primary dentition. Her remaining permanent teeth were loosened with severe alveolar bone loss, but calculus deposit was minimal. Significantly, there was no palmar-plantar hyperkeratosis. General examination showed normal data except for the increase of the immunoglobulin concentrations. In neutrophil function tests chemotaxis was depressed, although phagocytosis, random migration and superoxide production were within normal limits. Histologically, neutrophils were seen in the gingival tissue and other findings were also similar to those of adult periodontitis. In immunohistological examination, IgG-bearing cells which mostly consisted of plasma cells predominated in the lesion. Considering the past history, the immunodeficiency and the absence of palmar-plantar hyperkeratosis, the case was diagnosed as prepubertal periodontitis.     

Numerical identification of teeth in Japanese shrew-moles, Urotrichus talpoides and Dymecodon pilirostris.

Numerical determination of the teeth of two species of Japanese shrew moles, Urotrichus talpoides and Dymecodon pilirostris (Talpidae, Insectivora), was based on the position of the premaxillo-maxillary suture, comparison of the dentitions of the two species with those of their relatives and the supernumerary tooth. The premaxillo-maxillary suture is situated between the fifth and sixth tooth anterior to the M1, and the fifth tooth anterior to the M1 was determined to be C both in the two species. The supernumerary tooth which appears in the gap between the third and fourth anterior to the M1 of the lower jaw of Urotrichus talpoides was considered as a relic of pdl which seems to have been lost relatively recently in the evolution of this species. It was also shown that the first premolar of the upper jaw of the Urotrichus talpoides and the first premolars of the Dymecodon pilirostris are dihyodont. Retention of the dihyodont first premolars in these species seems to be a primitive character and is significant in determining the phylogenetical positions of these species.     

Inhibitory effect of synthetic histatin 5 on leukotoxin from Actinobacillus actinomycetemcomitans

Actinobacillus actinomycetemcomitans is a gram-negative bacterium strongly implicated in the pathogenesis of juvenile periodontitis. This periodontal pathogen synthesizes a leukotoxin that destroys human polymorphonuclear leukocytes (PMNs), and this toxin is thought to be responsible for the virulence of A. actinomycetemcomitans. It was therefore of interest to assess whether major virulence factors of periodontal pathogens were neutralized by salivary components. This study focuses on the effect of histatins, components of the nonimmune oral defense system, on leukotoxin activity. Leukotoxin was extracted with polymyxin B from freshly grown anaerobic cultures of A. actinomycetemcomitans strain Y4. PMNs isolated from blood of healthy human volunteers were incubated in a cytotoxicity assay containing PMNs (10(7) cells/ml) and leukotoxin preparation (0-500 microg/ml) in Hanks' balanced salt solution at 37 degrees C for 0-120 min with or without synthetic histatin 5 (0-500 microM). Cytotoxicity was measured by release of lactate dehydrogenase (LDH) at different time intervals. Histatin 5 neutralized the toxic effect of the leukotoxin preparation in a concentration-dependent manner, with an IC(50) value of 150 microM. When PMNs were preincubated with histatin 5 (300 microM), washed and subsequently exposed to leukotoxin, no protective effect was observed. This observation suggests a mechanism of inhibition whereby histatin 5 either directly neutralizes the leukotoxin or interferes with the leukotoxin-PMN interaction. The inhibitory effect of histatin 5 on leukotoxic activity may suggest a new biological function of histatins in the oral cavity as a naturally occurring secondary antibiotic.     

Clinical application of a new compact CT system to assess 3-D images for the preoperative treatment planning of implants in the posterior mandible A case report

When treatment planning before placing dental implants in the posterior region of the mandible, the locations of the inferior alveolar nerve and mental foramen need to be ascertained, as they determine the bone height available and the implant length selected. The purpose of this study was to introduce the clinical application of a newly developed compact computed tomography system (Ortho-CT) to assess three-dimensional (3-D) images for the preoperative treatment planning of implants in the posterior region of the mandible. To evaluate the 3-D images, we scanned using the Ortho-CT system the mandible with a radiopaque template placed in the posterior region. The Ortho-CT images provided excellent information for evaluating the morphology of the mandible, and for showing the location of the inferior alveolar nerve, mental foramen and the relationship of the template to the bone. We consider that Ortho-CT is a useful aid to preoperative treatment planning of implant therapy in the mandible.     

Effect of occlusal trauma on healing of periapical pathoses: report of two cases

AIM: To present two clinical cases and demonstrate that occlusal trauma may affect healing of periapical pathoses. SUMMARY: Two teeth with periradicular disease did not respond successfully to conventional root canal treatment or endodontic surgery. Occlusal adjustment was finally performed on both cases. After occlusal adjustment, uncomplicated healing and periapical repair occurred in both cases. The findings in these two cases suggest that occlusal trauma may play a role in the healing of periapical pathoses. KEY LEARNING POINTS: Occlusal trauma is positively correlated with changes in periodontal tissues. Although experiments in animals have shown that application of forces to teeth will not induce further periodontal destruction, we believe that some failures of root canal treatment may be due to the presence of occlusal trauma modulating the responses of inflamed periapical tissues or apical pathoses with persistent infection.