A retrospective study of the risk factors for ridge expansion with self-tapping osteotomes in dental implant surgery.

PURPOSE: To analyze the risk factors associated with the survival of self-threading implants placed with the ridge expansion technique using self-tapping osteotomesafter at least 24 months. MATERIALS AND METHODS: This retrospective study followed patients for at least 2 years in whom implants had been inserted by means of the ridge expansion technique. The patient was taken as the unit of analysis, and the loss of any implant as a result of mobility at any time during the follow-up period was considered as a failure. A number of patient variables were recorded: sociodemographic (age/sex), anatomical (bone quantity/quality, expansion zone), infection history (prior antibiotic therapy for active infection), prosthodontic(type of provisional prosthesis and type of definitive rehabilitation), and surgical (number of surgical stages, the use of biomaterials or atraumatic maxillary sinuselevation). Risk factors were expressed as values of relative risk (RR) and the odds ratio. RESULTS: Seventy-four patients (157 implants) were followed over a mean period of 38.8 ± 7.7 months. Most patients (91.9%) did not lose any implants, and failures occurred mainly after implant loading (5.4%). Sociodemographic factors (sex and age) were not associated with a significant risk of implant failure. However, the existence of previous local infection (RR = 34.0), the use of an immediate fixed provisional prosthesis (RR = 15.0), and type D3 bone (RR = 5.1) were seen to be the main risk factors involved in this technique for the period assessed. CONCLUSIONS: The risk of failure when implants are placed using self-tapping osteotomeswas highest in patients who had active local infection; immediate provisionalization and less dense bone were also associated with additional risk of failure.