Prostaglandin 阻害剤の実験的歯周炎における歯槽骨骨動態に及ぼす影響に関する研究

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Alveolar bone loss is the most striking feature of periodotitis in humans and animals. Many chemical mediators have been known to activate osteoclasts, and prostaglandins (PGs) are included in them. Since the levels of PGs increase in inflamed gingiva of humans with periodontitis, PGs would play the main role of alveolar bone destruction in periodontitis. Recently some investigators reported that indomethacin, a potent inhibitor of PG synthesis, reduced the macroscopic bone loss and the number of ostoclasts in some experimental model of periodontitis. But the bone always changes in the architecture by remodeling in which bone formation follows resorption. The inhibitor of PG synthesis may affect not only bone resorption but also formation. In order to understand the change of bone dynamics after administration of such drugs, bone histomorphometry, initiated by Frost et al, is very useful. This study was designed to determine the effect of flurbiprofen, a potent inhibitor of PG synthesis, on alveolar bone loss and the alveolar bone dynamics during experimental periodontitis in dogs by histomorphometry. In both medicated and non-medicated groups, dental floss ligature was placed around the second, third, and fourth premolars of the left jaw during a 32-day experimental period. The second, third and fourth premolars of the right jaw served as control. Evaluation of the dynamics of appositional bone growth was facilitated by subcutaneus administration of calcein and oxytetracycline. Administration began on day 10 of the experimental period with the use of a schedule of 2 days on (calcein), 8 days off, 2 days on (calcein), 8 days off and 2 days on (oxytetracycline). The dosage was about 10 mg/kg/day for calcein and 300 mg/kg/day for oxytetracycline. Medicated group was given daily administration of flurbiprofen (0.2 mg/kg/day) from days 22 to 32. At the end of this experimental period, the dogs were killed. The mandibles were removed and fixed immediately in 70% ethanol, dehydrated and embedded without demineralization in polyester resin. Sections, about 100μm thick, were prepared for histomorphometry. Frontal sections were divided into two segments, shallow side (S) and deep side (D). The alveolar bone surface on shallow and deep segments were further divided into two segments for measuring parameters of bone surface, gingival side (G) and periodontal side (P). The alveolar cortices on shallow and deep segments were further divided into two segments for measuring parameters of internal remodeling, buccal side (Bu) and lingual side (Li). The morphometric measurments were taken at these sites using a computer-based system. The following parameters were measured on alveolar bone surface : the fractional resorption surface (Lr), the active resorption surface ratio (aLr), the number of osteoclasts per 1 mm of active resorption surface (ocNo./arl), the number of osteoclasts (ocNo.), the fractional bone surface with osteoid seam (osLf), and the oxytetracycline single labeled surface ratio (tcLf). The following parameters were measured in alveolar cortex : the number of resorption cavities (Ar), the number of osteons with osteoid seam (osAf), the number of oxytetracycline single labeled osteons (tcAf), the proportion of mineral appositional rate of inflamed to control side (rMo), and the length of circumference of labeled osteon (Sl). The results were as follows : 1. Lr were significantly decreased in gingival side by flurbiprofen. 2. Neither aLr nor ocNo./arl were changed by flurbiprofen. 3. ocNo. were considerably decreased in gingival side by flurbiprofen. 4. Both osLf and tcLf were somewhat increased in gingival side by flurbiprofen. 5. Ar were somewhat decreased by flurbiprofen. 6. osAf were not changed, while tcAf were slightly increased by flurbiprofen. 7. rMo were not changed by flurbiprofen, and Sl were not different between medicated and non-medicated groups. These results show that flurbiprofen depress the bone resorption in experimental periodontitis but does not affect the activity of activated osteoclasts, and that it gives some effect during the reversal phase of bone remodeling sequence, the intermediate step between resorption and formation.
九州歯科学会の論文
1986-02-25

Prostaglandin 阻害剤の実験的歯周炎における歯槽骨骨動態に及ぼす影響に関する研究

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