Computer-guided miniscrew insertion in the paramedian and parapalatal areas of the palatal vault: failure rate and learning curve required to obtain predictable results.

Aim: The objective of the present study was to evaluate the failure rate of palatal computer-guided miniscrews placed in the paramedian (PM) and parapalatal (PP) regions for orthodontic purposes. An additional aim was to investigate whether a learning curve was required to perform computer-guided miniscrew insertion as well as to evaluate the peri-implant soft tissue response at three follow-up time points.

Materials and methods: A total of 202 palatal computer-guided miniscrews were inserted in 78 subjects for orthodontic purposes. A surgical guide was designed after planning the appropriate insertion sites on 3D images created by the fusion of CBCT scans and digital dental model images. The orthodontic appliances were disassembled monthly to perform a percussion test and evaluate the mobility of each miniscrew. To determine whether a learning curve was required for computer-guided miniscrew insertion, the time point of miniscrew failures and the number of surgeries were evaluated. Bleeding on probing (BOP) and probing pocket depth (PPD) were recorded for each miniscrew at 2- (T0), 6- (T1), and 12-month (T2) follow-up time points.

Results: An immediate failure rate of 4.95% was recorded due to lack of primary stability immediately following miniscrew insertion, with a statistically significantly higher failure rate of PP miniscrews (P = 0.00). Failure of the miniscrews occurred at random times, with no learning curve required for their insertion. The measured BOP rates (mean: 3.13%) and PPD values (mean: 1.68 mm) remained stable over time.

Conclusions: Computer-guided miniscrew insertion in the palatal vault showed a low failure rate without a determined learning curve required for their insertion to obtain predictable results and with long-term stability of peri-implant soft tissue indices.