Guided tissue regeneration with bioabsorbable and expanded polytetrafluoroethylene barrier membranes in the treatment of naturally occurring periodontal defects in dogs.

The purpose of the present study was to evaluate the healing events and compare the effects of guided tissue regeneration (GTR) using 3 different membranes: a weakly cross-linked bioabsorbable bovine collagen membrane; a strongly cross-linked bioabsorbable bovine collagen membrane; and a non-resorbable ePTFE membrane. Twenty adult female beagle dogs with naturally occurring periodontitis were subjected to periodontal probing and scaling. In both right and left mandibular quadrants, mucoperiosteal flaps were raised, and after debridement, the roots of experimental premolar teeth received apical reference notches. The following treatments were randomly assigned: 1) gingival flap curettage (GFC) + ePTFE membrane, control membrane; 2) GFC + slightly cross-linked collagen membrane, 1st test membrane; and 3) GFC + strongly cross-linked collagen membrane, 2nd test membrane. The flaps were sutured in such a manner that the membranes were completely covered. All dogs received a soft diet for a 2-week period and an oral hygiene program until time of sacrifice. The animals were randomly scheduled for sacrifice at 2, 4, 12, and 24 weeks. The ePTFE membranes still in place were removed at 6 weeks. The jaws were dissected and specimens prepared for descriptive histology and histomorphometry. The early resorption of the 1st test membrane was achieved at 4 weeks, and the 2nd test membrane at 12 weeks, both with normal inflammatory reaction. Measurements of epithelium, connective tissue attachment, new bone, and neocementum were compared within an animal (paired t test). Analyses were performed on data at 4, 12, and 24 weeks post-healing; little differences were found between these periods. Limited connective tissue repair was favored by the placement of all the membranes (about 20%), with no statistically significant difference. These findings indicate that bioabsorbable collagen membranes with different cross-linking and ePTFE barriers promote similar new attachment in GTR procedures on naturally occurring periodontal defects in dogs.

Regeneration of rat calvarial defects using a bioabsorbable membrane technique: influence of collagen cross-linking.

The aim of the present study was to examine the influence of cross-linking on collagen membranes used for guided bone regeneration of calvarial defects in rats. In 48 Wistar rats, divided equally into 4 groups, 1 control and 3 experimental, standardized transosseous circular calvarial defects were made midparietally. In the control group, the defect was only covered by the soft tissue flap while in the 3 experimental groups, 3 differently cross-linked collagen membranes were interposed between the osseous defect and the overlying flap before suturing. The healing was assessed at 10, 20, and 30 days after surgery. The results showed that augmenting the degree of collagen cross-linking diminished the membrane resorption rate. Compared to the sham-operated sites, the membrane protected defects showed significantly more bone regeneration (on average 4 times more) as attested by histology and measured by histomorphometric analysis. Although the bone gain seemed to augment with increasing degrees of cross-linking, the results within the 3 experimental groups were not statistically different. Since longer healing periods might have been necessary to substantiate results within experimental groups, a study is currently undertaken to evaluate this aspect. This study demonstrated the efficacy of collagen membranes in guiding bone regeneration, as well as the importance of the type and degree of cross-linking.

Tomodensitometric and histologic evaluation of the combined use of a collagen membrane and a hydroxyapatite spacer for guided bone regeneration: a clinical report.

In this report, the problems of insufficient bone and soft tissue after extraction of maxillary incisors were addressed concurrently prior to endosseous implant placement, by combining the use of a diphenylphosphorylazide-cross-linked Type I collagen membrane and a resorbable space-making biomaterial composed of 200-micron porous hydroxyapatite granules blended in Type I collagen and chondroitin-4-sulfate. Upon flap reflection 8 months postsurgery, the horizontal deficiencies were almost completely resolved, membranes completely resorbed and the defects filled with hard, bonelike tissue, with a few superficial hydroxyapatite granules. Histologic evaluation of the bone biopsies obtained at the implantation sites revealed dense, well-reconstructed alveolar bone with a few traces of hydroxyapatite granules that had been completely resorbed. Tomodensitometric evaluation indicated that bone regeneration ranged from 14% to 58%, with an average bone gain of 29.77%. Four nonsubmerged ITI titanium implants placed in the augmented bone have been in function for more than 5 years, with no clinical or radiographic signs of hard or soft tissue breakdown. Bacterial sampling at dental sites with periodontitis 1 month prior to periodontal therapy and at implant sites for up to 30 months demonstrated rapid colonization of implant surfaces by periodontopathogens without causing any detrimental effect to implant integration.

Guided bone regeneration for immediate non-submerged implant placement using bioabsorbable materials in Beagle dogs.

The aim of the present study was to evaluate the combined application of different bioabsorbable materials for healing of residual peri-implant defects after placement of non-submerged implants into fresh extraction sockets. Second and third mandibular premolars were extracted from 10 Beagle dogs, the coronal part of the distal sockets were surgically enlarged and this was followed by immediate placement of specially designed hollow-screw non-submerged dental implants. For each animal, the coronal peri-implant defects were further treated with one of the 4 following procedures: 1) no treatment, control site; 2) grafting with porous hydroxyapatite (HA); 3) collagen membrane tightly secured around the implant and over the defect and 4) grafting with HA covered with a collagen membrane. After 16 weeks of healing, specimens were removed from the mandibule and prepared for a histomorphometric evaluation. The bone-to-implant contact length (BIC) was measured and compared amongst the different treatment modalities. In the defect area, the irregular bone regeneration was similar between all the treatment procedures (P > 0.10). In the sites covered with a collagen membrane alone, the total BIC (47%) was greater than in control sites (28.7%, P < 0.05) or sites grafted with HA (22.2%, P < 0.02). Total BIC in sites treated with the HA-membrane combination (43%) was only significantly different from sites treated with HA (P < 0.05). It is concluded that the use of bioabsorbable materials results in a limited increase of osseointegration when used in conjunction with immediate placement of non-submerged implants, although the principle of the one stage surgical approach can be maintained.