Effect of alveolar ridge preservation interventions following tooth extraction: A systematic review and meta-analysis

The aim of this systematic review was to critically analyse the available evidence on the effect of different modalities of alveolar ridge preservation (ARP) as compared to tooth extraction alone in function of relevant clinical, radiographic and patient-centred outcomes.A comprehensive search aimed at identifying pertinent literature for the purpose of this review was conducted by two independent examiners. Only randomized clinical trials (RCTs) that met the eligibility criteria were selected. Relevant data from these RCTs were collated into evidence tables. Endpoints of interest included clinical, radiographic and patient-reported outcome measures (PROMs). Interventions reported in the selected studies were clustered into ARP treatment modalities. All these different ARP modalities were compared to the control therapy (i.e. spontaneous socket healing) in each individual study after a 3- to 6-month healing period. Random-effects meta-analyses were conducted if at least two studies within the same ARP treatment modality reported on the same outcome of interest.A combined database, grey literature and hand search identified 3,003 records, of which 1,789 were screened after removal of duplicates. Following the application of the eligibility criteria, 25 articles for a total of 22 RCTs were included in the final selection, from which nine different ARP treatment modalities were identified: (a) bovine bone particles (BBP) + socket sealing (SS), (b) construct made of 90% bovine bone granules and 10% porcine collagen (BBG/PC) + SS, (c) cortico-cancellous porcine bone particles (CPBP) + SS, (d) allograft particles (AG) + SS, (e) alloplastic material (AP) with or without SS, (f) autologous blood-derived products (ABDP), (g) cell therapy (CTh), (h) recombinant morphogenic protein-2 (rhBMP-2) and (i) SS alone. Quantitative analyses for different ARP modalities, all of which involved socket grafting with a bone substitute, were feasible for a subset of clinical and radiographic outcomes. The results of a pooled quantitative analysis revealed that ARP via socket grafting (ARP-SG), as compared to tooth extraction alone, prevents horizontal (M = 1.99 mm; 95% CI 1.54-2.44; p < 0.00001), vertical mid-buccal (M = 1.72 mm; 95% CI 0.96-2.48; p < 0.00001) and vertical mid-lingual (M = 1.16 mm; 95% CI 0.81-1.52; p < 0.00001) bone resorption. Whether there is a superior ARP or SS approach could not be determined on the basis of the selected evidence. However, the application of particulate xenogenic or allogenic materials covered with an absorbable collagen membrane or a rapidly absorbable collagen sponge was associated with the most favourable outcomes in terms of horizontal ridge preservation. A specific quantitative analysis showed that sites presenting a buccal bone thickness >1.0 mm exhibited more favourable ridge preservation outcomes (difference between ARP [AG + SS] and control = 3.2 mm), as compared to sites with a thinner buccal wall (difference between ARP [AG + SS] and control = 1.29 mm). The effect of other local and systemic factors could not be assessed as part of the quantitative analyses. PROMs were comparable between the experimental and the control group in two studies involving the use of ABDP. The effect of other ARP modalities on PROMs could not be investigated, as these outcomes were not reported in any other clinical trial included in this study.Alveolar ridge preservation is an effective therapy to attenuate the dimensional reduction of the alveolar ridge that normally takes place after tooth extraction.