Ridge preservation following tooth extraction using a polylactide and polyglycolide sponge as space filler: a clinical and histological study in humans.

BACKGROUND The placement of different graft materials and/or the use of occlusive membranes to cover the extraction socket entrance are techniques aimed at preserving/reducing alveolar ridge resorption. The use of grafting materials in fresh extraction sockets has, however, been questioned because particles of the grafted material have been found in alveolar sockets 6-9 months following their insertion. AIM The aims of the study were to (i). evaluate whether alveolar ridge resorption following tooth extraction could be prevented or reduced by the application of a bioabsorbable polylactide-polyglycolide sponge used as a space filler, compared to natural healing by clot formation, and (ii). evaluate histologically the amount and quality of bone tissue formed in the sockets, 6 months after the use of the bioabsorbable material. MATERIAL AND METHODS Thirty-six patients, undergoing periodontal therapy, participated in this study. All patients were scheduled for extraction of one or more compromised teeth. Following elevation of full-thickness flaps and extraction of teeth, measurements were taken to evaluate the distance between three landmarks (mesio-buccal, mid-buccal, disto-buccal) on individually prefabricated stents, and the alveolar crest. Twenty-six alveolar sockets (test) were filled with a bioabsorbable polylactide-polyglycolide acid sponge (Fisiograft), while 13 sockets (controls) were allowed to heal without any filling material. The flaps were sutured with no attempt to achieve primary closure of the surgical wound. Re-entry for implant surgery was performed 6 months following the extractions. Thirteen biopsies (10 test and three control sites) were harvested from the sites scheduled for implant placement. RESULTS The clinical measurements at 6 months revealed, in the mesial-buccal site, a loss of bone height of 0.2 mm (1.4 SD) in the test and 0.6 mm (1.1 SD) in the controls; in the mid-buccal portion a gain of 1.3 mm (1.9 SD) in the test and a loss of 0.8 mm (1.6 SD) in the controls; and in the distal portion a loss of 0.1 mm (1.1 SD) in the test and of 0.8 (1.5 SD) mm in the controls. The biopsies harvested from the test sites revealed that the new bone formed at 6 months was mineralized, mature and well structured. Particles of the grafted material could not be identified in any of the 10 test biopsies. The bone formed in the control sites was also mature and well structured. CONCLUSION The results of this study indicate that alveolar bone resorption following tooth extraction may be prevented or reduced by the use of a bioabsorbable synthetic sponge of polylactide-polyglycolide acid. The quality of bone formed seemed to be optimal for dental implant insertion.