Is simultaneous placement of orthodontic mini-implants and skeletally anchored appliances advisable? : CBCT-based...

For the fabrication of an orthodontic mini-implant (OMI)-borne appliance, the position of the inserted OMI can be detected by a silicone impression or an intraoral scan (IOS). In case of digital planning, it can be taken over from the planning and the appliance can be produced in advance. This study aimed to evaluate the accuracy of these three techniques and whether there is an association with the insertion angle.

Two OMIs were digitally planned and placed in the anterior palate of 11 human cadavers with different insertion angles. Subsequently, the position of each OMI was detected by an IOS, a silicone impression, and a cone-beam computed tomography (CBCT) scan, whereby the CBCT scan was set as "real position". The measurements of accuracy were performed between the CBCT data as a reference and the preoperative digital planning, the IOS and the plaster model manufactured from the silicone impression.

The IOS was the most accurate in detecting the Top (mean deviation 0.14 mm) and the Apex (mean deviation 0.36 mm) of the OMIs. Significant linear deviations between the three modalities were registered for both Top (p < 0.001) and Apex (p = 0.010). The digital planning procedure achieved the lowest mean angular deviation of 3.7° and was significantly more accurate in this respect than the IOS (p < 0.001).

All methods were subject to small, but clinically irrelevant deviations. Within the limitations of a cadaver study, all methods appear to be suitable for clinical use. However, the digital workflow could be advantageous, requiring only a single visit for OMI placement and simultaneous appliance fitting.