Ridge Preservation With or Without an Osteoinductive Allograft: A Clinical,
Tomography, and Histologic Study
Evaluating Dimensional Changes and New Bone Formation of the Alveolar Ridge
Lauren A. Brownfield*† and Robin L. Weltman†
Background: The aim of this randomized, controlled clinical trial is to determinewhether ridge preservation using an osteoinductive allograft (test) would prevent ridge resorption and promote bone maturation compared to extraction alone (control).
Methods: Seventeen patients (20 total sites), in need of a non-molar extraction and delayed implant placement were randomly selected to receive either ridge preservation or extractionalone.Acone-beamcomputed tomographywascompleted with a radiographic stent in place before extraction and 10 to 12 weeks postoperatively for dimensional and buccal plate analyses. Bone cores were taken for micro-computed tomography (microCT) and histologic analyses.
Results: Resorption of the alveolar ridge occurred at all sites with no statistically significant differences found between test and control sites. A significant correlation was found between the initial buccal plate thickness and the loss of vertical ridge height. microCT and histologic analyses found a mean new bone volume of 44.9% with microCT and 37.4% with histology in test sites and 39% and 35.5%, respectively, in control sites.
The residual graft volume was 2.4% with microCT and 4.5% with histology.
Conclusions:Test and control sites lost similar amounts of alveolar ridge, with the loss of buccolingual width occurring predominately at the expense of the buccal bone. A thicker buccal plate was associated with less ridge loss in the vertical dimension. The percentage of new bone was not statistically significant between either the test or control sites, using either microCTorhistologic analyses. J Periodontol 2012;83:581-589.
Alveolar bone loss; alveolar ridge; controlled clinical trial; randomized clinical trial; tooth extraction.
A s dental implants continue to have improved success and as patient access and acceptance grows, the standards for implant treatment and success are raised. Clinicians strive to fulfill both the esthetic and functional needs of the restoration, to include a gingival profile harmonious with the adjacent healthy dentition. However, soft- and hard-tissue defects resulting from trauma, infection, and tooth loss create an anatomically less favorable foundation for such success. In general, the alveolar bone remodeling that occurs after tooth loss yields diminished alveolar ridge dimensions in both the vertical and horizontal planes. Studies have reported that the ridge alterations after tooth loss may result in a 40% to 60% bone loss height and width as early as 3 months.1-5 Hence, preservation of the original alveolar ridge should aid the surgeon in achieving the optimal placement of the implant with the desired implant diameter while maintaining the esthetics of the overlying soft tissues. On average, grafted extraction sites have reported a loss of width <2mm and a loss* Private practice, Houston, TX. † Department of Periodontics, University of Texas Health Science Center at Houston,
Houston, TX. doi: 10.1902/jop.2011.110365
J Periodontol • May 2012 581 of height <0.5 mm, with the majority of cases able to have the implant placed without additional augmentation, whereas non-grafted extraction sites have reported losses of ridge width from 2 to 6 mm and ridge height of 1 mm, with great variation.2,3,5,6 In addition, the success rates of implants placed in grafted sockets have been reported to be comparable to success rates of implants placed in native bone.7,8
Some studies question the benefit of bone replacement grafts within an extraction socket, claiming that some bone grafts interfere with normal extraction socket healing.9 Most bone graft materials have been found to provide a scaffold for bone ingrowth, ameans of osteoconductive bone formation. Some materials, suchas autografts, assist bone formationbyosteogenesis, osteoinduction, and osteoconduction. In general, allografts have been found to support bone growth through osteoconductive properties. Some lots of allograft that have been shown to contain the bone growth factor bone morphogenetic protein are considered osteoinductive. Comparisons of the osteoinductive potential of different batches of allografts from different commercial bone processing banks and different lots from within the same banks have found unpredictable or poor bone formation with most of the lots tested. The variability has been found to be related to the age of the donor as well as to the content of bone-inductive factors in the donor bone, with a possible association with processing techniques.10,11
The aim of this randomized, controlled clinical trial is to determine whether ridge preservation using an osteoinductive allograft would prevent ridge resorption compared to extraction alone. The second aim is to evaluate how the thickness of the initial buccal plate affects the resorption of the alveolar ridge. The final aimof this study is to usemicro-computerized tomography (microCT) and undecalcified histology to determine whether the osteoinductive allograft improved the amount and maturity of new bone formation compared to extraction alone.
MATERIALS AND METHODS
Patients presented to the University of Texas Health
Science Center at Houston (UTHSCH), Houston,
Texas, for treatment of a single non-molar, non-restorable, or hopeless toothwith adjacent teethpresent, and who were interested in an implant restoration, were invited to participate in this study. These patients were given oral and written information regarding the study, and their written informed consent was obtained. The study protocol was approved by the Committee for the Protection of Human Subjects at UTHSCH.
At the initial exam, the patients completed a comprehensive exam that was reviewed for the following exclusion criteria: 1) untreated periodontal disease, endodontic lesions, and/or caries (beyond the hopeless tooth considered for this study); 2) vertical and/ or moderate or severe horizontal bone loss; 3) uncontrolled or severe systemic diseases; 4) medical conditions or takingmedication associated with compromised bone healing; 5) current smokers or previous smokers reporting >10 cigarettes per week; 6) pregnancy; 7) extensive parafunctional habits; and 8) inadequate oral hygiene to include a plaque control record >20%.