Accurate pre-surgical determination for self-drilling miniscrew implant placement using surgical guides and cone-beam computed tomography.

Miniscrew implants have proven to be effective in providing absolute orthodontic anchorage. However, as self-drilling miniscrew implants have become more popular, a problem has emerged, i.e. root contact, which can lead to perforation and other root injuries. To avoid possible root damage, a surgical guide was fabricated and cone-beam computed tomography (CBCT) was used to incorporate guide tubes drilled in accordance with the planned direction of the implants. Eighteen patients (5 males and 13 females; mean age 23.8 years; minimum 10.7, maximum 45.5) were included in the study. Forty-four self-drilling miniscrew implants (diameter 1.6, and length 8 mm) were placed in interradicular bone using a surgical guide procedure, the majority in the maxillary molar area. To determine the success rates, statistical analysis was undertaken using Fisher's exact probability test. CBCT images of post-surgical self-drilling miniscrew implant placement showed no root contact (0/44). However, based on CBCT evaluation, it was necessary to change the location or angle of 52.3 per cent (23/44) of the guide tubes prior to surgery in order to obtain optimal placement. If orthodontic force could be applied to the screw until completion of orthodontic treatment, screw anchorage was recorded as successful. The total success rate of all miniscrews was 90.9 per cent (40/44). Orthodontic self-drilling miniscrew implants must be inserted carefully, particularly in the case of blind placement, since even guide tubes made on casts frequently require repositioning to avoid the roots of the teeth. The use of surgical guides, fabricated using CBCT images, appears to be a promising technique for placement of orthodontic self-drilling miniscrew implants adjacent to the dental roots and maxillary sinuses.