Resumen de Evaluation of Healing at Molar Extraction Sites With and Without Ridge Preservation: A Randomized Controlled Clinical Trial
Christopher J. Walker, Thomas J. Prihoda, Brian L. Mealey, David J. Lasho, Marcel E. Noujeim, Guy Huynh-Ba
Background: To date, limited evidence is available specifically evaluating ridge preservation (RP) and implant placement in molar sites. The primary aim of this study is to radiographically compare alveolar ridge changes with and without RP with cone-beam computed tomography (CBCT).
Methods: This parallel, two-arm randomized clinical trial included 40 patients evenly distributed between two treatment groups. After molar extraction, sites were allowed to heal naturally or received RP with freeze-dried bone allograft covered by a non-resorbable dense polytetrafluoroethylene membrane. CBCT scans were taken immediately and 3 months postextraction, and then a dental implant was placed. Width and height measurements were made radiographically.
Results: Significantly greater loss in alveolar ridge height was found in molar sites allowed to heal without RP on the buccal aspect of the socket (RP: −1.12 ± 1.60 mm versus no RP: −2.60 ± 2.06 mm, P = 0.01). No significant difference in ridge width loss was found between groups. Two-thirds ridge width reduction was experienced on the buccal aspect in sites without RP, but width loss was evenly distributed between buccal and lingual aspects when RP was performed. Bone grafting at time of placement was required in 25% of implants in the group without RP versus 10% of implants in the RP group.
Conclusions: In molar extraction sites without RP, significantly more reduction in ridge height occurred, and the majority of ridge width loss was localized to the buccal aspect. When RP was performed, ridge width loss was not significantly decreased, but the loss was evenly distributed between facial and lingual aspects of the extraction site.
Natural healing consequences of alveolar remodeling after tooth extraction include three-dimensional bone remodeling and ridge atrophy.1,2 After tooth extraction, bundle bone lining the extraction socket is resorbed.3 These cellular remodeling events result in clinically observed dimensional changes at premolar and molar sites, with up to 50% of the ridge width lost within 12 months after extraction.4 The majority of this loss is observed within the first 3 months and is slightly higher in mandibular molar regions.4 A systematic review by Van der Weijden et al.5 reported 3.87 mm reduction in alveolar width postextraction from the natural course of healing. A systematic review evaluating effects of ridge preservation (RP) in non-molar regions compared with an untreated control found weighted mean differences in height changes favoring RP by 0.62 to 2.9 mm.6 With respect to differences in width changes, a range of 0.42 to 3.25 mm less dimensional change was reported, favoring RP groups. It has also been shown that the buccal aspect of the alveolar ridge experiences more resorption than the lingual aspect.7 These natural reductions in ridge dimensions may limit restoratively driven implant placement as a tooth replacement option.
Single-rooted extraction sites have been more commonly evaluated in the literature than molar sites, and those that have been typically include both molar and premolar sites.8,9 RP has been advocated at anterior postextraction sites to better achieve esthetic results due to the very thin nature of the buccal plate.10-12 Molar extraction sites differ anatomically from single-rooted sites in terms of greater socket orifice, multiple root prominence areas with different buccal and lingual plate dimensions, and the presence of varying volumes of interseptal and furcal bone.
Restoratively driven implant placement is critical in creating a proper foundation for a successful outcome, both functionally and esthetically.13 RP has been shown to limit the natural dimensional changes that occur after tooth extraction.6,8,9,14 However, the outcome of RP specific to molar sites is limited to date. Radiographic measurements using cone beam computed tomography (CBCT) have been shown to be accurate within 0.28 ± 0.29 mm compared with direct measurements at extraction sites for buccal and labial plate thicknesses.15 Therefore, the objective of this clinical study was primarily to determine dimensional alveolar changes radiographically and to clinically determine changes of the soft tissue encountered after molar extraction with and without RP. Secondarily, this study evaluated the necessity of RP in molar sites to successfully place a restoratively driven dental implant as a molar replacement, specifically on the influence of the buccal bone thickness on alveolar ridge dimensional change.
