実験的歯周炎が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 an essential phenomenon of periodnotitis in humans and animals. The main cause of this bone loss is inflammation. Recently, ligature induced periodontitis have been used to study the pathological alternations of the periodontal tissues in dogs. Bones always change the shape and structure by modeling and remodeling. Modeling changes the architecture, the dimension and the total amount of the affected tissue. Remodeling is a turn over mechanism that need not necessarily (but may) alter the geometry or dimensions of bone by BMU, basic multicellular unit, which comprises semimicroscopic formation one. Periodontitis not only resorbs the bone but may alter this dynamic process. This study was designed to determine the effect of ligature induced periodontitis on alveolar bone dynamics in dogs with histmorphometry. Periodontitis was induced around the third and fourth premolars on the left side of the mandible by ligating a nylon floss around the teeth and into the gingival sulcus for four, six and eight weeks. The right side on which ligature was not applied served as the control. Evaluation of the dynamics of appositional bone growth was facilitated by subcutaneous administration of calcein. Administration began 13 days before the end of the study with the use of a schedule of 3 days on, 7 days off and 3 days on. The dosage of calcein was about 8 mg/kg per day. After killing the dogs, the specimens were prepared for bone histmorphometry. Morphometric measurement was taken with the microcomputer-based system. Before measurement, alveolar half of frontal-sectional mandible was divided into four segments, upper buccal (Bu), lower buccal (Bl), upper lingual (Lu), and lower lingual (Ll). The bone surface on upper buccal and upper lingual segments were divided into four surfaces, buccal gingival (BG), buccal periodontal (BP), lingual gingival (LG), and lingual periodontal (LP). The following parameters were measured on alveolar bone surface : the length of Howship's lacunae surface (Lr), the length of osteoid surface (Lf) and the number of osteoclasts per 1 mm of Howship's lacunae surface (Noc/Lr). The following parameters were measured in alveolar cortex : the number of resorption cavities per square mm (Ar), the number of secondary osteons with osteoid seam per square mm (osAf), the number of calcein labeled osteons per square mm (calAf), the appositional rate of bone matrix mineralization in microns per day (Mo) and the length of circumference of calcein label per osteon (Sl). The results were as follows : 1. Lr, Lf and Noc/Lr were markedly higher in value in the inflamed than in the control side. 2. In the inflamed side, Lr and Noc/Lr were higher in value on the gingival than on the periodontal surface. Lf did not show the difference between them. In the control side, these three parameters did not show the difference between them. 3. Ar, osAf and calAf were significantly higher in value in the inflamed than in the control side. Especially, Ar was significantly increased at four weeks, and osAf and calAf were significantly increased at eight weeks. 4. Mo showed significantly positive correlationship with Sl in the inflamed and in the control side, but did not increase or decrease with inflammation. 5. Internal remodeling activated most on upper buccal segment. These results suggest that periodontitis causes bone resorption followed by bone formation on the bone surface, and activates internal remodeling in the cortex, but does not suppress these process.
九州歯科学会の論文
1984-02-25

実験的歯周炎が歯槽骨骨動態に及ぼす影響に関する研究

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