Straight versus angled screw channel considerations in anterior maxilla using CBCT for planning immediate implant...

The purpose of this radiographic study was to assess the variability and probability of straight and angled screw channel access while planning immediate implant placement for maxillary anterior teeth using cone beam computed tomography (CBCT).

Anterior maxillary CBCT scans of patients were reviewed for maxillary central incisors, lateral incisors, and canines. The scans were imported to implant planning software. Mid sagittal sections were identified, implants were virtually placed using established clinical criterion, and virtual straight abutments were planned on those sites. The emergence of the abutment access channels was checked, and angular corrections were incrementally made from 5 to 25 degrees till the access channels were lingual to the incisal edges. The prevalence of each angulation and degrees of angulation were then compared among the tooth types by using Fishers' Exact test.

A total of 295 sites in the anterior maxilla were evaluated. The results demonstrated that the greatest percentage of straight access channels was found at canine sites (51%) and the least at lateral incisors (5.1%). There was a significant increase in access channel through the cingulum using angled screw channel systems (p < 0.01) for each tooth type. The lateral incisor required the most significant angle correction among the anterior teeth. The most frequently required angle correction was 10 degrees (18.6%) within the sample (p < 0.01).

The study showed that the angled screw channel systems significantly (p < 0.01) increased the prevalence of a screw-retained restoration in the anterior maxilla. Lateral incisors required the greatest amount of angle correction within the group (75.5%).