Comparative Study of Buccal Dehiscence Defects in Immediate, Delayed, and Late Maxillary Implant Placement with Collagen Membranes: Clinical Healing Between Placement and Second Stage Surgery

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Comparative Study of Buccal Dehiscence Defects in Immediate, Delayed, and Late Maxillary Implant Placement with Collagen Membranes: Clinical Healing Between Placement and Second Stage Surgery
September 2003
Mills, Michael P. DMD, MS
Implant Dentistry: Volume 12(3) September 2003 p 200
Lippincott Williams & Wilkins
Department of Prosthodontics
University of Texas Health Science Center at San Antonio
7703 Floyd Curl Drive
San Antonio, TX 78284-7894
Editors' Note: Please be aware that articles reviewed in this segment of Implant Dentistry are selected by the Editors and are assigned to be reviewed by knowledgeable individuals. These are not fillers. Each article has been carefully analyzed and diligently reviewed.
: David R. Cagna, DMD,* Scott R. Dyer, DMD,** Gary A. Hartman, DDS, MS,*** Robert M. Loughlin, DDS,ǃÜ; Michael P. Mills, DMD, MSǃ?;
Comparative Study of Buccal Dehiscence Defects in Immediate, Delayed, and Late Maxillary Implant Placement with Collagen Membranes: Clinical Healing Between Placement and Second Stage Surgery C. E. Nemcovsky, Z. Artzi, J Periodontol, 2002;73:754-761
Successful placement and restoration of dental implants is highly dependent on the volume of bone present. Where bone grafting and barrier membrane placement is indicated in conjunction with dental implant placement, the ability to obtain and maintain primary soft tissue coverage could be critical to the overall functional and esthetic results. In this study, the authors investigated the clinical bone healing of maxillary buccal type dehiscent defects around 102 dental implants grafted with Bio-Oss and covered with a Bio-Gide collagen membrane. Microtextured (42), titanium-plasma-sprayed (56), and hydroxyapatite-coated (4) dental implants were placed following one of three treatment protocols. In group 1, 23 implants were placed in 19 patients into immediate extraction sites and closed with a rotated split palatal flap. In group 2, 39 implants were placed in 25 patients in a delayed manner following a short healing period after tooth removal and coverage of the extraction site with a full-thickness rotated palatal flap. In group 3, 40 implants were placed in 22 patients following at least 6 months of healing after tooth extraction.
Dental implants were placed according to the surgical techniques outlined by the implant system being utilized. Following implant stabilization, the distance from the most apical aspect of the buccal crest to the fixture platform was recorded as the defect height. The widest mesiodistal dimension of the bony defect was recorded as the defect width. After grafting and barrier membrane application, the implants were allowed to heal for 6 to 8 months. At second-stage surgery defect height and width were again recorded. Resolution of defect height and width was reported as the millimeter linear change (bone gain) between stage I and stage II surgeries; the percentage area of defect fill at stage II was also calculated.
Group 1 (immediate placement) demonstrated a defect height of 4.6 ¨± 1.10 mm (2-7 mm range) at stage I and 1.1 ¨± 0.80 mm (0-2.5 mm range) at stage II for an average bone gain of 3.5 mm. Stage I defect width was 4.1 ¨± 0.78 mm (3-6 mm range) and 1.3 ¨± 0.89 mm (0-2.5 mm range) for an average gain of 2.8 mm. The percent reduction in defect area was 90.2 ¨± 9.15. Group 2 (delayed) demonstrated a defect height of 6.6 ¨± 1.90 mm (3.3-11 mm range) at stage I and 0.6 ¨± 0.74 mm (0-3 mm range) at stage II for an average bone gain of 6.0 mm. Stage I defect width was 4.3 ¨± 0.79 mm (2.3-6 mm range) and 0.7 ¨± 0.84 mm (0-3 mm range) for an average gain of 3.6 mm. The percent reduction in defect area was 95.6 ¨± 8.73. Group 3 (6 months after extraction) demonstrated a defect height of 5.4 ¨± 1.92 mm (3-10 mm range) at stage I and 1.2 ¨± 0.88 mm (0-2.6 mm range) at stage II for an average bone gain of 4.2 mm. Stage I defect width was 3.6 ¨± 0.97 mm (2.3-6 mm range) and 1.3 ¨± 0.79 mm (0-2.5 mm range) for an average gain of 2.3 mm. The percent reduction in defect area was 87.6 ¨± 11.48. Group 3 had seven cover screws exposed, followed by group 1 (five) and group 2 (two). All implants osseointegrated and all defects appeared to be clinically healed. The percent defect area and height reduction was highest in the delayed-placement group (group 2) followed by the immediate-placement group (group 1). Although these differences were statistically significant, they were not deemed to be clinically significant. Cover screw exposure did not adversely affect defect resolution.
The delayed-placement protocol used in group 2 appears to be the method of choice when bone augmentation using a barrier membrane is anticipated. The authors state that the closure of an extraction site with a rotated palatal flap appears to hasten healing and improve the tensile strength of the soft tissue. This would allow for early implant placement, which has been reported to aid in maintaining bony and soft tissue morphology. These are factors critical to restoring implants in the anterior esthetic zone. In addition, the improved quality of the soft tissue could potentially reduce the risk of membrane exposure after guided bone-regeneration procedures, as well as cover screw exposure, in two-stage implant systems. (See Nemcovsky CE et al, J Periodontol. 1999;70:926-934 and Nemcovsky CE, et al. Int J Oral Maxillofac Implants. 2000;15:843-852 for a review of the rotated palatal flap techniques.)
¨© 2003 Lippincott Williams & Wilkins, Inc.