Fogorvosi szemle, 2007 (100. évfolyam, 1-6. szám)

2007-10-01 / 5. szám

224 - FOGORVOSI SZEMLE

defects were treated with one of the following therapies: a) Guided Tissue Regeneration (GTR), b) EMD, c) EMD + GTR, or d) with open flap debridement surgery (control). The histological investigation has shown that in the control defects the healing was characterized by a long junctional epithelium and a limited periodontal regeneration. The treatment with GTR, EMD and EMD + GTR resulted in formation of cementum with inserting collagen fibres as well as of alveolar bone [58, 59]. Comparable results were also reported in spontaneous intrabony and experimentally created intrabony, recession and dehiscence-type defects in rats, dogs and monkeys [60-64], A histomorphometrical study in dogs has evaluated the effectiveness of EMD to induce regeneration of periodontal tissues in Class II furcation lesions with or without GTR [65], Experimental Class II furcations were made in the premolars of 4 dogs. The furcation defects were filled with gutta percha to induce an inflammatory response and to prevent spontaneous repair. 21 days after creation of the defects following treatments were performed: a) Guided Tissue Regeneration (GTR), b) EMD, or c) with open flap debridement surgery (control). The histological analysis at 8 weeks following therapy has revealed that in the control group healing was characterized by formation of a long junctional epithelium and limited bone formation. Treatment with EMD led to significant regeneration of the furcation lesions while the association with membranes was detrimental. Another study has evaluated histologically in monkeys the healing of mandibular Classlll furcation defects following treatment with: a) Guided Tissue Regeneration (GTR), b) EMD, c) EMD + GTR, or d) with open flap debridement surgery (control) [66]. The results have shown that treatment with GTR or EMD + GTR resulted in formation of new cementum with inserting collagen fibers while new bone was filling the defects in the situation where the membrane was not exposed. The sites treated only with EMD exhibited new attachment and new bone formation to a varying extent, while the control sites presented only limited new attachment and bone formation.

In conclusion, the data from animal studies indicate that EMD is present on the treated root surfaces for a period of at least 4 weeks and predictably promotes formation of cementum, periodontal ligament and bone in fenestration, recession, intrabony and mandibular Classll furcation defects.

Results from human histological studies

Results of the first human-histological biopsy were published by Heijl [67], A recession defect on a lower incisor was surgically created and treated with EMD. After a healing period of 4 months, the tooth as well as the surrounding soft and hard tissue was extracted and histologically evaluated. The histological investigation

■ 100. évf. 5. sz. 2007.

showed that a new layer of acellular root cementum covered 73% of the original defect depth. New alveolar bone has regenerated on 65% of the initial bone height. In another study Yukna and Mellonig [68] treated 10 intrabony periodontal defects in 8 patients with EMD. The histological analysis 6 months after the treatment has shown in 3 biopsies a complete periodontal regeneration (i.e. new formation of root cementum, periodontal ligament and alveolar bone), while in 3 further biopsies, the healing was characterized by a new connective tissue attachment (i.e. new cementum with inserting collagen fibers). Four biopsies healed by a long junctional epithelium and without any signs of periodontal regeneration. In a comparative clinical and histological investigation the healing of intrabony periodontal defects was evaluated following treatment with EMD or Guided Tissue Regeneration (GTR) with a bioabsorbable barrier [69]. Six months after therapy, the clinical attachment level (CAL) showed a mean gain of 3.2 ± 1.2 mm in the EMD group and of 3.6 ± 1.7 mm in the GTR group. The histological analysis showed that in both groups the healing was mainly characterized by periodontal regeneration [69]. The mean value of new cementum and periodontal ligament amounted to 2.6 ± 1.0 mm in the EMD group and to 2.1 ± 1.0 mm in the GTR group. The mean value of new alveolar bone was 0.9 ± 1.0 mm in the EMD group and 2.1 ±1.0 mm in the GTR group. A reparative healing by a long junctional epithelium occurred only in one biopsy from the EMD group. The results of the study have provided evidence that treatment with EMD promotes periodontal regeneration in humans and may lead to comparable clinical and histological results to GTR therapy. These results were confirmed in subsequent reports by other authors, not only in intrabony but also in recession-type defects [70-75]. Subsequent immunohistological studies have shown that following surgery EMD remains up to 4 weeks on the root surface and, the wound healing and/or remodelling process can be followed for a period of up to 6 months after treatment with EMD therapy [76-78], A very recent human histological study has attempted to characterize the tissues developing on the root surface at 2 to 6 weeks following treatment of intrabony defects with EMD [79, 80]. The results have shown that the newly formed tissues on the root surfaces were thick, collagenous, devoid of extrinsic fibers, and had an irregular surface contour. The presence of electron-dense, organic material in the collagenous matrix indicated at least partial mineralization. Embedded cells were numerous and the cells on the matrix surface were very large in size. It was concluded that following treatment with EMD, a bone-like tissue resembling cellular intrinsic fiber cementum may develop on the root surfaces, instead of acellular extrinsic fiber cementum. Furthermore, EMD may both induce de novo formation of a mineralized connective tissue on scaled root surfaces and stimulate matrix deposition on old native cemen-