Movement of periodontally affected teeth after guided tissue regeneration (GTR)--an experimental pilot study in animals.

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The purpose of the present experimental animal study was to examine the relevance of regenerative periodontal therapy (membrane procedure, application of enamel matrix proteins) to subsequent orthodontic tooth movement. After extraction of the third premolars in four foxhounds, 64 three-wall bony defects were artificially generated at the first and second premolars and colonized by periodontopathogenic microorganisms. After 6 months, regenerative periodontal therapy was performed: scaling, conditioning of the root surfaces with citric acid, combination of enamel matrix protein (Emdogain, Biora, Malmö, Sweden) and resorbable Vicryl membrane (Ethicon, Norderstedt, Germany). The defects at the first premolars served as the control group. In the test group eight second premolars were intruded 1 month after surgical intervention; in addition eight premolars were translatorily distalized, i.e. moved both into the defect (pressure side) and away from the defect (tension side). Qualitative histologic analysis was performed on non-decalcified microsection samples using the polychrome sequential labeling and histomorphometry. The histologic findings revealed extensive periodontal regeneration in the control group, at the intruded root segments, and on the tension sides. Cemento- and osseoneogenesis yielded mean values of 70-80%, whereas values for epithelial down-growth were low. The bony regeneration on the pressure side was markedly reduced; however, nearly 70% new formation of root cementum with Sharpey's fibers was also recorded. Periodontal regenerative procedures appear to enhance conditions for the movement of teeth with attachment loss; clinical testing is promising.