Effect of loading time on the success of complete mandibular titanium implant retained overdentures: a systematic review

Objectives: The aim of this review was to compare conventional against early/immediate loading protocols of implant-retained overdentures (IOD) in the edentulous mandible. Material and methods: Medline search via Ovid to extract prospective comparative studies on trials comparing the effect of timing of loading initiation on the success of mandibular IOD. The outcome of major interest was marginal bone loss. Probing depth, plaque, bleeding index and mobility were also assessed. Indices at 12 and 24 months were compared and changes assessed. Outcomes were entered into RevMan (version 4.2.5) for meta-analysis. Results: Of 239 articles, only nine trials fulfilled the criteria and involved 30 immediate, 71 early, 77 one-stage conventional, and 66 two-stage conventional subjects. Three immediate loading trials showed an increase in the amount of marginal bone loss over time, while the majority of early and conventionally loaded implants exhibited a decrease in the amount of bone loss in the second year compared with the first 12-month period. Probing depth at 24 months showed a significant difference between early and conventional loading; SMD 0.5 (95% confidence interval 0.03, 0.97). No other statistically significant differences were found between either immediate or early and conventional loading for any indices. Conclusions: No deleterious effects up to 24 months have been shown from immediate or early loading. Conventional loading after a 3-month healing period has not been proven to be the only acceptable protocol for mandibular IOD, but further long-term studies are needed to confirm this.