Buccal Bone Formation After Flapless Extraction: A Randomized, Controlled Clinical Trial Comparing Recombinant Human Bone Morphogenetic Protein 2/Absorbable Collagen Carrier and Collagen Sponge Alone

• Localización: Journal of periodontology, ISSN 0022-3492, Nº. 4, 2014, págs. 525-535
• Idioma: inglés
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• Resumen

  • Background: Flapless extraction of teeth allows for undisturbed preservation of the nearby periosteum and a source of osteoprogenitor cells. Recombinant human bone morphogenetic protein 2 (rhBMP-2) has been used for different bone augmentation purposes with great osteoinductive capacity. The aim of this study is to compare the bone regenerative ability of rhBMP-2 on an absorbable collagen sponge (ACS) carrier to a collagen sponge (CS) alone in extraction sites with =50% buccal dehiscence.

    Methods: Thirty-nine patients requiring extraction of a hopeless tooth with =50% buccal dehiscence were enrolled. After flapless extraction and randomization, either rhBMP-2/ACS carrier or CS alone was placed in the extraction site. After extraction, a baseline cone beam computed tomography (CBCT) scan was obtained of the site, and a similar scan was obtained 5 months postoperatively. Medical imaging and viewing software were used to compare the baseline and 5-month postoperative images of the study site and assess ridge width measurements, vertical height changes, and buccal plate regeneration.

    Results: Radiographically, CBCT analysis showed that with =50% of buccal bone destruction, rhBMP-2/ACS was able to regenerate a portion of the lost buccal plate, maintain theoretical ridge dimensions, and allow for implant placement 5 months after extraction. The test group performed significantly (P <0.05) better in regard to clinical buccal plate regeneration (4.75 versus 1.85 mm), clinical ridge width at 5 months (6.0 versus 4.62 mm), and radiographic ridge width at 3 mm from the alveolar crest (6.17 versus 4.48 mm) after molar exclusion. There was also significantly (P <0.05) less remaining buccal dehiscence, both clinically (6.81 versus 10.0 mm) and radiographically (3.42 versus 5.16 mm), at 5 months in the test group. Significantly (P <0.05) more implants were placed in the test group without the need for additional augmentation. The mean loss in vertical ridge height (lingual/palatal) was less in the test sites but was not significantly (P = 0.514) different between the test and control groups (0.39 versus 0.64 mm).

    Conclusions: rhBMP-2/ACS compared to CS alone used in flapless extraction sites with a buccal dehiscence is able to regenerate lost buccal plate, maintain theoretical ridge dimensions, and allow for implant placement 5 months later.

    Partial or complete destruction of the buccal bony plate may occur before or after tooth extraction. Teeth may have some buccal plate missing for a number of reasons, such as infection, trauma during extraction, and vertical root fracture. Options for grafting these buccal plate defects are numerous and include reflection of a full-thickness flap and grafting of the buccal dehiscence defect using a guided bone regeneration (GBR) procedure. Several GBR techniques exist for treating localized defects1,2 and defects around implants3 and may be used to successfully aid in bone regeneration.3-6 However, by reflecting a full-thickness flap, the periosteum and partial blood supply to the buccal plate are disrupted. Classic literature studies report a loss of buccal alveolar bone following full-thickness flap reflection ranging from 0.47 to 0.63 mm.7-9 In animal models, research demonstrates less resorption of the buccal plate using a flapless extraction technique compared to one involving reflection of a flap.10 The reported amount of resorption of the buccal alveolar bone crest was 0.7 mm more in the extraction sites that were done following full-thickness flap reflection. Araújo and Lindhe11 reported detrimental effects on the tooth adjacent to extraction sites following full-thickness flap reflection. There was significantly greater connective tissue attachment loss on the buccal aspect of the tooth adjacent to the extraction site as well as an increase in the distance from the cemento-enamel junction to the alveolar crest. Using a flapless extraction technique may prevent disruption of the periosteum, blood supply, and source of osteoprogenitor cells on the outer surface of the buccal plate. Preosteoblasts have been found on the innermost surface of the periosteum and have the capacity to proliferate and express proteins that are associated with mature osteoblasts.12 The growth factor recombinant human bone morphogenetic protein 2 (rhBMP-2) on an absorbable collagen sponge (ACS) carrier has shown potential for enhanced bone formation when used as a graft material.13-15 rhBMP-2 has the ability to induce osteogenesis and angiogenesis, is chemotactic for mesenchymal stem cells,12,16 and may allow for a more rapid chemotactic response to aid in regeneration of the buccal plate when it is placed in localized alveolar defects. Early research by Urist17 led to the discovery of proteins that were able to induce bone formation ectopically in an animal muscle-pouch model. Later, Wozney et al.18 determined that these bone-inducing proteins were part of the transforming growth factor-ß (TGF-ß) superfamily. They were also able to purify and clone bone morphogenetic proteins (BMPs) as part of the TGF-ß superfamily.18 More recent clinical research on rhBMP-2 has demonstrated its potent bone-inducing capabilities.14,19 Fiorellini et al.14 evaluated the effectiveness of different concentrations of rhBMP-2 placed in localized alveolar extraction socket defects following full-thickness flap reflection. The results showed that a dose-dependent amount of bone growth occurred with increasing rhBMP-2 concentration and that the ideal concentration of rhBMP-2 for grafting purposes was 1.5 mg/mL. Misch19 expounded on the rhBMP-2 bone growth evidence by performing a case series in patients requiring extraction. In that study, the extraction sockets had a loss of >50% of the buccal bone height. A flapless extraction technique was used, the tooth was extracted, and the remaining socket and buccal defect were grafted with 1.5 mg/mL rhBMP-2 on an ACS carrier and a cortico-cancellous bone allograft. The results from this case series of 10 extractions showed that there was a range of 0.63 mm gain in ridge width to a loss of 2.18 mm, and all dental implants were successfully placed into these sites without the need for additional augmentation.19 To date, there have been no published randomized clinical trials using rhBMP-2/ACS for treatment of extraction sockets in the presence of a buccal dehiscence following a flapless extraction. The aim of this study is to evaluate the bone-regenerative capacity of rhBMP-2/ACS carrier versus collagen sponge (CS) alone placed in a flapless extraction site with =50% of a buccal dehiscence defect. The CS alone was chosen as the control to specifically isolate the effect of rhBMP-2 growth factor on buccal plate regeneration. Cone beam computed tomography (CBCT) images of the extraction site at baseline were compared to CBCT images 5 months after extraction. The authors� hypothesis is that by performing a flapless extraction technique and minimizing the disruption of the periosteal blood and cellular supply, rhBMP-2 aids in a more rapid chemotactic response from the nearby undisturbed osteoprogenitor cells of the periosteum and, hence, more regeneration of the deficient buccal plate.