Biomaterials for the Reconstructive Treatment of Periodontal Intrabony Defects. Part II. Guided Tissue Regeneration, Biological Agents and Combination Therapies

The biological principle of GTR is based on experimental studies demonstrating that the progenitor cells capable of forming new cementum with inserting collagen fibers (i.e. new connective tissue attachment) have their source in the periodontal ligament. By placing a mechanical barrier to cover the periodontal defects, the downgrowth of the epithelial cells can be stopped and the stability of the blood clot ensured. Consequently, the wound area and the previously ‘plaque-infected’ root surfaces can be repopulated by cells originating from the intact periodontal ligament and alveolar bone (Nyman et al, 1982; Gottlow et al, 1984, 1986; Karring et al, 1993). The first clinically tested mechanical barrier was the Millipore®‚ filter followed by the nonresorbable e-PTFE membranes (Nyman et al, 1982; Gottlow et al, 1984, 1986; Karring et al, 1993). The first human case treated with GTR was reported by Nyman et al, (1982). A deep intrabony defect localized at a lower incisor scheduled for extraction due to very advanced destruction of the attachment apparatus was treated with a Millipore®‚ filter according to the biological principle of GTR. Following removal of granulation tissue an 11 mm deep periodontal defect was diagnosed. A membrane was adapted in order to fully cover the intrabony defect and 2–3 mm of the surrounding alveolar bone. Histological evaluation after 3 months of healing revealed that new cementum with inserting collagen fibers had formed on the previously plaque-exposed root surface. In a later investigation Gottlow et al (1986) treated 12 intrabony defects with GTR. Histological documentation was also presented in five out of the 12 cases. The results demonstrated the formation of considerable but varying amounts of new cementum, new periodontal ligament and new bone. The observed variability in the results was attributed to factors such as the amount of remaining periodontal ligament, defect morphology, surgical technique and bacterial contamination of the membrane. These observations were later confirmed in controlled animal and human studies Biomaterials for the Reconstructive Treatment of Periodontal Intrabony Defects. Part II. Guided Tissue Regeneration, Biological Agents and Combination Therapies