Interventions for replacing missing teeth: 1- versus 2-stage implant placement

Abstract

Implants may be placed penetrating the oral mucosa (1-stage procedure) or can be completely buried under the oral mucosa (2-stage procedure) during the healing phase of the bone at the implant surface. With a 2-stage procedure the risk of having unwanted loading onto the implants is minimized, but a second minor surgical intervention is needed to connect the healing abutments and more time is needed prior to start the prosthetic phase because of the wound-healing period required in relation to the second surgical intervention. To evaluate whether a 1-stage implant placement procedure is as effective as a 2-stage procedure. The Cochrane Oral Health Group's Trials Register, The Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE were searched. Handsearching included several dental journals. Authors of all identified trials, an internet discussion group and 55 dental implant manufacturers were contacted to find unpublished randomised controlled trials (RCTs). The last electronic search was conducted on 15 January 2007. All RCTs of root-form osseointegrated dental implants comparing the same 2-piece osseointegrated root-form dental implants placed according to 1- versus 2-stage procedures with a minimum follow up of 6 months after loading. Outcome measures were: prosthesis failures, implant failures, marginal bone level changes on intraoral radiographs, patient preference including aesthetics, aesthetics evaluated by dentists, and complications. Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two review authors. Authors were contacted for missing information. Results were expressed as random-effects models using mean differences for continuous outcomes and risk ratios for dichotomous outcomes with 95% confidence intervals (CI). Heterogeneity was to be investigated including both clinical and methodological factors. Three RCTs were identified and two trials including 45 patients in total were included. On a patient, rather than per implant basis, there were no statistically significant differences. The number of patients included in the trials was too small to draw reliable conclusions, however it appears that the two procedures did not show clinical significant differences. If these preliminary results will be confirmed by more robust trials, a 1-stage procedure might be preferable since it avoids one minor surgical intervention and shortens the waiting time to provide the final restoration. There might be specific situations though, such as when optimal implant stability is not obtained at placement or when barriers are used in conjunction with implants, in which a 2-stage approach might be preferable.