Two implant placement methods are used in oral implantology: submerged (S, two-stage surgical procedure) and non-submerged (NS, one-stage surgery). However, a quantitative assessment of their influence on implant osseointegration, summarising the whole present experience, is not directly possible, owing to the lack of normalisation of the published results. To overcome this difficulty, selection criteria have been applied to the latter in a process of a meta-analysis of specialised literature, in order to authorise a pooled treatment with an adequate statistical method. Survival life tables are established (up to 15 and 10 years respectively for S and NS implants placed in normal situations) for extended samples (13049 S and 5515 NS implants). Early (before loading) failure rates and 95% confidence level ranges of cumulative implant survival rates are shown. For both categories, the quality of the placement stage remains critical to ensure optimal osseointegration behaviour. Both categories match current survival requirements, but with a quite different behaviour over time. NS implants, while osseointegrating better initially, are subject to causes of osseointegration loss, which persist over a longer period of time. Implant design characteristics (including the type of surface) seem to be more relevant than the placement procedure for the implant's behaviour. This is in agreement with recent histological and preliminary clinical results, and should be confirmed by further studies.

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