Does the Generation to Which the Operator Belongs Influence the Orthodontic Miniscrew Insertion Accuracy in Dynamic Computer-guided Surgery?

This study will be conducted to evaluate intergenerational differences regarding orthodontic miniscrew placement accuracy in the palatine vault through dynamic computer-guided surgery. The secondary outcome will be to assess, for each operator, the correlation between the number of miniscrews inserted, i.e. surgeries, and the accuracy variables as well as the duration of interventions.

The clinical investigation will be conducted between December 2022 and September 2024, adhering to the ethical standards outlined in the seventh revision of the Declaration of Helsinki. Parents and guardians are going to be informed about the details of the study, including the benefits and potential risks, and provided written consent. The investigation is approved by the local ethics committee (no. 5951).

The eligibility criteria are: (1) children in late mixed dentition or permanent dentition, (2) need for orthodontic treatment, (3) good oral hygiene, (4) absence of acute infection in the oral cavity, (5) good general health. The exclusion criteria are as follows: (1) syndromic patients, (2) uncontrolled systemic disease.

Miniscrews will be placed by three different clinicians, belonging to three different generations and levels of experience in implant and orthodontic miniscrew placement in free-hand and static computer-guided surgery.

A block randomization sequence is going to be generated using the Sealed Envelope online tool (https://www.sealedenvelope.com) to allocate the subjects into three groups. The random allocation sequence generation, enrollment, and assignment of the participants to interventions will be done by an external researcher not involved in the research. The allocation ratio of the subjects will be balanced, based on the generation to which the researchers belong.

Group A is going to be treated by operator number 1, an oral surgeon with more than 30 Years of experience, which belongs to "Generation X"; operator number 2 (MG) will treat Group B and is a dentist with 15 years of experience in oral surgery and belonged to "Generation Y"; Group C will be treated by operator number 3 (DB), a final year dental student with no previous experience in oral surgery, that belonged to "Generation Z". However, all three were novices in the use of dynamic computer-guided surgical systems, and no pre-clinical training phase was done.

In order to achieve skeletal anchorage for orthodontic or orthopedic treatment, the miniscrews (BENEfit®, Benefit system; PSM Medical Solutions, Tuttlingen, Germany) will be inserted under local anesthesia, in the paramedian area of the hard palate at the level of the third palatine rugae, and to guarantee a minimally-invasive, flapless and pre-drilling free approach, the miniscrews will be inserted using the Navident dynamic navigation system (ClaroNav Technology Inc., Toronto, Canada), through a NSK iSD900 cordless battery screwdriver (Nakanishi INC., Tochigi, Japan).

The patients will undergo to optical scanning, using a Medit i700 intraoral scanner (Medit Corp., Seoul, South Korea) and CBCT imaging of the upper jaw, captured using a Scanora 3Dx cone-beam device (Soredex, Tuusula, Finland).

The resulting STL (Standard Triangulation Language) and DICOM (Digital Imaging and Communications in Medicine) files are going to be superimposed to precisely determine the insertion site, diameter, and length of the miniscrews to achieve bicortical anchorage.

To evaluate the accuracy of miniscrew placement and to detect any potential root injury, a postoperative CBCT scan was conducted immediately after each surgical procedure.

The preoperative and postoperative images were superimposed, through the use of EvaluNav software (ClaroNav Technology Inc., Toronto, Canada), employing coordinated automatically given by the software as previously described [3, 10, 26]. To assess the differences between the planned position and the actual placement of miniscrews, five deviation parameters will be analyzed: Entry-3D, Entry-2D, Apex-3D, Apex vertical (vertical deviation), Angular deviation (Figure 2) The duration of the surgeries will be calculated by an external researcher using the Navident Software (ClaroNav Technology Inc., Toronto, Canada) from the moment when the Navigation View appears to the end of the navigation phase.

The sample size was calculated based on a previous study using G*Power software (version 3.1.9.6; Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany). The significance level was set at 0.05 and the power at 0.8. A total sample size of thirty-three os considered acceptable, with an actual power of 0.81.

To reduce the risk of statistical analysis bias, the operator variable will be coded, and a blinded statistician will perform the statistical analysis, using Excel (Microsoft, Redmond, Washington, USA) to create a database to allocate the subjects, and the statistical software package SPSS version 27.0 (IBM Corp., New York, USA).

Descriptive statistics analysis (including mean, minimum, maximum values, confidence interval at 95% and standard deviations) is going to be performed for each variable within each group.

Subsequently, the Shapiro-Wilk normality test will be conducted to assess the distribution of the data. For variables following a normal distribution, the ANOVA test will be employed; whereas, for variables exhibiting a non-normal distribution, a non-parametric test, namely the Kruskal-Wallis H test, is performed. In cases where the tests indicated statistically significant differences, post-hoc tests will be subsequently conducted. The Tukey test is going to be used for variables with a normal distribution, and the Dunn's for a non-normal distribution.

Furthermore, the Pearson Correlation will be utilized to analyze whether the number of surgeries influenced the deviation variables (Entry-3D, Entry-2D, Apex-3D, Apex Vertical, Angular deviation, duration of the intervention).

The level of significance was set at P ≤ 0.05.