PERIODONTAL REGENERATION IN A BUCCAL DEHISCENCE MODEL IN MONKEYS AFTER APPLICATION OF ENAMEL MATRIX PROTEINS

There is increasing evidence that cells of the epithelial root sheath synthesize enamal matrix proteins and that these proteins play a funda mental role in the formation of acellular cementum, the key tissue in the development of a functional periodontium. The purpose of the prese nt study was to explore the effect of locally applied enamel matrix an d different protein fractions of the matrix on periodontal regeneratio n in a buccal dehiscence model in monkeys. Buccal, mucoperiosteal flap s were raised from the canine to the Ist molar on each side of the max illa. The buccal alveolar bone plate, the exposed periodontal ligament and cementum were removed. Various preparations of porcine enamel mat rix with or without vehicles were applied before the flaps were reposi tioned and sutured. After 8 weeks, the healing was evaluated in the li ght microscope, and morphometric comparisons were made. Application of homogenized enamel matrix or an acidic extract of the matrix containi ng the hydrophobic, low molecular weight proteins, amelogenins, result ed in an almost complete regeneration of acellular cementum, firmly at tached to the dentin and with collagenous fibers extending over to new ly formed alveolar bone. After application of fractions obtained by ne utral EDTA extraction containing the acidic, high molecular weight pro teins of the enamel matrix, very little new cementum was formed and ha rdly any new bone. The results of the controls in which no test substa nce was applied before the repositioning of the flap, were very simila r to those obtained with the EDTA extracted material. Propylene glycol alginate (PGA), hydroxyethyl cellulose and dextran were tried as vehi cles for the enamel matrix preparations. Only PGA in combination with the amelogenin fraction resulted in significant regeneration of the pe riodontal tissues.