Study design and registration
This trial was conducted based on the guidelines of Consolidated Standards of Reporting Trials guidelines (CONSORT), where all procedures were performed as were priorly scheduled (9) (Fig. 1). Patients attending the Department of Orthodontics at Damascus University, Dental School, were examined between Apri 2021 and November 2022. The present study was recorded at The ISRCTN registry (ID: ISRCTN65498676 Registration date: 07/04/2021) retrospectively, i.e., the registration was done after the onset of this trial. This two-arm, parallel-group, single center randomized clinical trial protocol was approved by the Local Research Ethics Committee Approval which was acquired from the University of Damascus (UDDS-588-2018GD/SRC-57782), and the funding for this trial was received from the Postgraduate Research Budget at Damascus University (Ref no: 34627726781JHM).
Sample Size Calculation
Sample size was calculated using the G*power 3.1.7 software presuming that a reduction of 30 per cent in total treatment duration could be evidenced with a power of 80 per cent at the 5 per cent significance level. The least clinically significant difference in the time needed for leveling and alignment of severely crowded incisors was assumed to be 52.8 days depending on a previous trial showing that anterior teeth alignment took a mean of 132 days with a standard deviation 39 days (10). Thus, a sample of 30 patients was required for both groups. To account for possible withdrawal, the final sample size for the study was set at 16 patients per group, yielding a total of 32 patients.
Patients’ Recruitment And Eligibility Criteria
After clinical examination of 96 patients at the Department of Orthodontics at University of Damascus Dental School, it was found that 40 individuals matched the inclusion criteria. All patients received sufficient explanation about the orthodontic and surgical steps in this trial, and then out of the participants who agreed to take part in this study, 32 were randomly recruited. Information sheets were provided to all selected patients; then, informed consent forms were obtained. The inclusion criteria were: (1) adult ASA I and II patients (I: Normal healthy patient; II: Patients with mild systemic disease) (11) within an age range 18–26 years, (2) maxillary severe crowding (> 6 mm) demanding extraction of the first premolars, (3) completion permanent dentation (except of third molars), (4) Little’s Index is greater than 10 mm, and (5) normal maxillary incisors inclination. The exclusion criteria were: (1) any disease impacting orthodontic movement, (2) medical conditions that would affect tooth movement (corbcosteroid treatments, NSAIDs consumpbon, bisphosphonates, hyperparathyroidism, osteoporosis, uncontrolled diabetes), (3) inadequate oral health, and (4) contraindication to oral surgery (medical–social–psychological).
Randomization, Allocation Concealment, And Blinding
Subjects were assigned into two parallel groups with a 1:1 allocation ratio by computer-generated list of random numbers. Allocation series was hidden using numbered, opaque, sealed envelopes which were opened at the premolars extraction session. First group received 3D guided piezocisison-assisted orthodontic treatment, while the second group received conventional one. Random allocation sequence generation, patient assignment to interventions ,the allocation concealment and outcomes processing were assigned to one of the academic stuff at the Department of Oral and Maxillofacial Surgery(not involved in this research).However, Blinding of personnel and participants was not viable.
Orthodontic Procedures
Orthodontic treatment using traditional metal brackets (Master Series®, American Orthodontics, Sheboygan, Wisconsin, USA), with a 0.022-inch slot high and MBT prescription were used. Then the brackets were bonded after 7 days of the first upper premolars extraction. In both groups, the archwire sequence was as follows: 0.012-inch Nitinol (NiTi), 0.014-inch NiTi, 0.016-inch NiTi, 0.016×0.022-inch NiTi, 0.017×0.025-inch NiTi, and finally 0.019×0.025-inch stainless steel (SS) (American Orthodontics, Sheboygan, Wisconsin, USA) (5). Replacing wires was accomplished when the used wire became neutral with the ability to insert the next wire without applying exaggerated force. Leveling and alignment was considered finished when LII was less than 1 mm, indicating complete alignment of the anterior teeth and the final archwires were easily and passively inserted into all brackets(12).
3d Piezocision Surgical Procedure
In the experimental group, piezocision surgery was performed on the same premolars extraction day to minimize the number of anesthesia depending sessions in terms of patients` comfort and satisfaction. The patient was requested to rinse with 0.12% chlorhexidine gluconate (Oral-B, Procter & Gamble Company, USA) before applying the surgical intervention. The surgical procedure was performed, where 3 mm-deep and 5 to 8 mm-long incisions were conducted using a Piezosurgical micro-saw with a BS1 cutting tip (Implant Center™ 2, Satelec, France). Patients were asked to follow a soft diet for 2 days after the piezocision and apply mouth rinse for a week (7).
All of the above-mentioned aspects were pre-planned and applied by CBCT imaging and transferred to the casts in order to produce a reliable and precise surgical 3D guide (Fig. 2.3).
Outcome Measures
The primary outcome measure was the overall alignment time (OAT) required to complete anterior alignment of the maxillary dental arch. Follow-up of this trial was considered finished when the LII was less than 1 mm. The secondary outcome measure was the accuracy of the new surgical guide which assessed by detecting the 3D deviation of the piezocisions. The preoperative (piezocision planning) and postoperative (achieved piezocision position) scans were performed with the same parameters, then overlapping by a specific algorithm, which allowed the comparison of the virtually planned and the actual piezocision positions, was applied in order to assess the values of deviation. Three deviation parameters between each planned and placed piezocision were measured. Since the current trial was the first RCT studying the accuracy of 3D piezocision surgical guide, most common method for measuring difference between planned and actual inserted dental implants has utilized.
Statistical analysis
Parametric tests were used since Anderson-Darling Normality tests showed normal distributions of the collected data. Two-sample t-tests were used to detect significant differences between the two groups regarding OAT.
Single blinding was employed in this trial regarding outcome measure assessment and data analysis. Minitab® program version 17.0 (Minitab Inc., Pennsylvania, USA) was used to perform descriptive and inferential statistics.