Effectiveness of microosteoperforations in accelerating alignment of maxillary anterior crowding in adults: A randomized controlled clinical trial


This trial aimed to investigate the effectiveness of microosteoperforations (MOPs) in overall time taken for alignment of maxillary anterior crowding and to evaluate the alignment improvement percentage within 6 months between MOPs and control groups.


Thirty adult participants (25 females and 5 males; mean age, 22.66 ± 3.27 years) with moderate upper labial segment crowding were randomly assigned into intervention and control groups using block randomization. All participants had first premolar extractions, bonded conventional fixed appliances, and 0.014-in, followed by 0.018-in nickel-titanium archwire placement for initial alignment. The intervention group received a 3-mm deep MOPs procedure under local anesthesia using a Propel device (Propel Ortho Singapore, Pte, Ltd, Winstedt Rd, Singapore) on the labial attached gingivae of maxillary incisors at monthly visits until complete alignment. Little’s irregularity index was used to assess the overall changes and measure the change of tooth alignment of the 6 maxillary anterior teeth. Assessor blinding was employed.


There was no statistically significant difference in the median overall alignment duration between MOPs and control groups (139 days [95% confidence interval, 115.32-161.83] vs 143 days [95% confidence interval, 107.12-179.74]; hazard ratio, 0.829; P = 0.467). The MOPs procedure had no significant effect on the alignment duration ( P = 0.657) and no overall significant difference in alignment improvement percentage among 2 groups on the basis of time (F = 2.53; P = 0.124). No harm was encountered.


The application of MOPs is no more effective in accelerating initial orthodontic alignment than conventional treatment.

Trial registration

This trial was registered at the ISRCTN registry with the study ID ISRCTN15080404.


doi.org/10.1186/ISRCTN15080404 .


This work was supported by the Postgraduate Trust Fund, Faculty of Dentistry, Universiti Teknologi MARA .


  • The application of microosteoperforations (MOPs) is not more effective than conventional method.

  • The alignment rate in the MOPs group increased by average 4 days only.

  • Repetition of the MOPs monthly does not enhance the alignment improvement.

  • The level of initial Little’s irregularity index affects the length of alignment duration.

  • The higher the initial irregularity, the longer the alignment duration may be undertaken.

Prolonged orthodontic treatment exposes patients to iatrogenic effects in which the quality of oral health may be compromised, such as discomfort, enamel demineralization, and root resorption. Extended treatment duration could also decrease patients’ compliance and outcome satisfaction. Therefore, a shorter treatment period would offer mutual benefits to patients and clinicians. Recently, accelerated therapies have been highly sought after to race against time to reduce the extent of orthodontic therapy. Nevertheless, the implementation of any adjunctive techniques to expedite orthodontic tooth movement (OTM) demands more robust clinical evidence of its effectiveness before being marketed in our daily practice.

Advanced modalities to accelerate tooth movement mainly involves mechanical stimulation or invasive surgical methods. Pharmacologic methodologies such as drug injections are present but not routinely practiced because of concerns of its applicability, effectiveness, general health, and safety. Other interventions include light-emitting diode-mediated-photobiomodulation therapy and pulsed electromagnetic fields required compliance. The evidence pertaining to these methods is low and also not recommended in daily practice. Low-level laser therapy is a quick, noninvasive procedure that emits laser to desired mucosa areas of the moving tooth. The problem lies with the need to specify the ideal dose or energy density for it to become most optimum in expediting tooth movement. A minimally invasive periodontally accelerated OTM, piezocision, has proven to increase the rate but with the possibility of root damage during incisions and scarring. ,

Microosteoperforations (MOPs) is the latest minimally invasive modality performed by puncturing through the attached gingiva with minimal irritation to the bone. For maximum result, MOPs are performed closer to the focus teeth and distant from the anchor teeth. MOPs should also be applied around the target tooth to encourage more bone remodeling. MOPs stimulation is believed to induce regional acceleratory phenomenon, inducing an increase in inflammatory marker expressions such as cytokines and chemokines, amplifying inflammatory response, and activating bone resorption machinery. Through the production of osteoclast precursor cells and higher osteoclast activation, a faster rate of tooth movement can be expected.

The first clinical trial by Alikhani et al, investigated the rate of canine retraction with MOPs over 1 month, suggesting that MOPs are effective with a 0.6 mm/month increased in the rate of canine retraction. Although Attri et al, further investigated the rate of tooth movement using en-masse retraction, which suggested that MOPs seem to be able to accelerate the canine retraction rate by 0.31 mm/month. However, these randomized clinical trials were in their infancy and insufficiently explored. Limited time and data could not support any clinical application in comprehensive orthodontic treatment. , These limitations have been overcome in recent research studies with modification and improvisation of techniques, timing, and measurements. However, this considerable interest has focused mainly on the rate of space closure by means of canine retraction only.

This study is the first to investigate the effectiveness of MOPs in accelerating the alignment of the anterior segment in the maxillary arch. Bearing in mind that this is the main motivation for most patients to undertake orthodontic treatment.

Specific objectives or hypotheses

The primary aim of this study was to compare the overall time taken to complete the alignment of maxillary anterior crowding. The secondary outcome was to evaluate the improvement percentage within 6 months between MOPs and control groups. The null hypothesis was that the adjunctive procedure of MOPs does not accelerate the orthodontic alignment rate compared to conventional orthodontic treatment.

Material and methods

Trial design and any changes after trial commencement

This study was a prospective, randomized, single-blinded, single-centered, 2-arm parallel controlled clinical trial, assessing the effectiveness of the new intervention of MOPs to reduce initial alignment treatment duration compared with conventional orthodontic treatment alone. There were no changes in methods after trial commencement.

Participants, eligibility, criteria, and setting

This trial was conducted at the Orthodontic Clinic, Faculty of Dentistry. Ethical approval was obtained from the Research Ethics Committee on September 29, 2017 (reference: 600-IRMI [5/1/6]; REC/297/17). This trial was registered at the ISRCTN registry with the study ID ISRCTN15080404.

Inclusion criteria were as follows: age range of 18-45 years, moderate crowding of the maxillary arch (5-8 mm), the canine relationship between Class III one-fourth unit up to Class II one-half unit, a full dentition including second molars, with a malocclusion requiring the extraction of maxillary first premolars. Healthy periodontal status with probing depth of ≤3 mm, full-mouth plaque score ≤20%, and full-mouth bleeding score ≤20 % (within 15 seconds after pocket depth probing). Exclusion criteria included previous orthodontic treatment, patients with systemic diseases, smokers, pregnant, and compromised periodontal oral health with evidence of bone loss and root resorption on the dental panoramic tomography as well as the history of dental trauma. Similarly, to patients with dental (eg, hyperdontia and hypodontia) or craniofacial anomalies (eg, cleft lip and palate) and on medications that could interfere with tooth movements, such as antiinflammatory drugs, systemic corticosteroids, or calcium channel blockers were further excluded.

Once the participant has agreed to the study protocol, a written consent that had been approved by the ethics committee was recorded.


Orthodontic procedures

Orthodontic treatment was carried out by multiple providers under the supervision of a central trial coordinator. Fixed appliances were bonded using conventional preadjusted edgewise brackets system with 0.022 × 0.028-in slot (MBT [McLaughlin, Bennett, and Trevisi], Victory Series; 3M Unitek, 3M Dental Products, Monrovia, Calif). Archwire sequence was similar for both groups, 0.014-in nickel-titanium (NiTi) followed by 0.018-in NiTi TruFlex NiTi archwire (Ortho Technology, Tampa, Fla). Complete alignment indicated the feasibility of inserting the 0.018-in NiTi archwire passively in all brackets. A laceback stainless steel wire (0.01-in) had been tied lightly from the canine to the first permanent molar on every quadrant to prevent deflection of the initial thin NiTi archwire during mastication.

MOPs procedure

MOPs were performed under local anesthesia infiltration (Lignocaine with 1:100,000 adrenaline) by the principal investigator to a standardized procedure protocol. MOPs group received surgical perforation within the attached gingiva to 1 mm apical to the mucogingival junction. Two holes were punctured at 3 mm apart on alveolar bone equidistant between the anterior teeth from maxillary right 3 to maxillary left 3 except in the midline alveolar bone ( Fig 1 ). Perforation dimensions were adopted from Alikhani et al, which was; 1.5 mm wide and 2-3 mm deep, using a disposable MOP device (Propel Ortho Singapore, Pte, Ltd, Winstedt Rd, Singapore). All participants were reviewed every 4 weeks, and MOPs were repeated monthly until the completion of the alignment stage. Protocol in this study was adapted from previous trials in which participants were refrained from taking analgesics. ,

Fig 1
An experimental model of MOPs was performed at interalveolar bone between maxillary right and left canines except in the midline.

After the MOPs procedure, participants were advised to avoid hot drinks and food until local anesthesia effects have diminished completely. Bleeding was arrested by local measures with cotton roll pressure over the perforation areas. Chlorhexidine mouthwash was prescribed to participants in the MOPs group. They were advised not to modify toothbrushing and flossing habits in the areas where MOPs have been performed.

Outcomes (primary and secondary) and any changes after trial commencement

The primary outcome measure was the overall time taken to complete the alignment of the anterior maxillary arch. The reading was taken from the patients’ clinical records. The total time taken was calculated by the number of days between baseline (M0) and complete alignment.

The secondary outcome was the alignment improvement percentage of the anterior maxillary teeth, which was observed up to the sixth month. Impression taking was carried out at each monthly visit (month 1 [M1], month 2 [M2], month 3 [M3], month 4 [M4], month 5 [M5], and month 6 [M6]) before fixed appliance manipulation and MOPs implementation. Consequently, model casts were fabricated with white stone up to the sixth month to monitor the treatment progress. The casts were labeled with the patients’ names and months of visit. Little’s irregularity index (LII) was used to assess the overall changes and measure the change of tooth alignment on the casts for proper, consistent accuracy by measuring the horizontal linear distance between adjacent contact points of the 6 maxillary anterior teeth. Perfect alignment was achieved once LII was 0 and indicated that the trial was completed. Measurements were calculated using a digital Vernier caliper (Stainless SL 246-15; Karl Hammacher GmbH, Solingen, Germany) with an accuracy of 0.01 ± 0.02 mm.

The alignment improvement percentage was calculated following the modified formula, which was adapted from AlSayed Hasan et al by dividing the amount of change in the LII value at a specific point in time (M1, M2, M3, M4, M5, M6 subtracting LII value at M1, M2, M3, M4, M5, M6 from the LII value of the previous month) by LII value at the respective month.

(M0 − M1)/M0 × 100% = improvement percentage.

Sample size calculation

The sample size was calculated to detect a significant mean difference of 28 days in overall alignment and leveling time of maxillary anterior crowding with a standard deviation of 15.29. It was determined that a minimum number of 9 patients were required in each group. The statistical power was set at 90%, with a 95% confidence interval (CI). The number of participants was increased to 15 per group in consideration for any dropouts.

Randomization (random number generation, allocation concealment, implementation)

All potential participants were screened for eligibility by the principal investigator and central trial coordinator. Participants who met the criteria were included sequentially and allocated randomly to the MOPs or control groups with a 1:1 allocation ratio. A random number table was employed, followed by a block of 6 numbers (3 odd and 3 even) to ensure even subjects in each group. Odd numbers were allocated to MOPs and even numbers to the control group. Cards were written with numbers and set in opaque sealed envelopes, which were kept by a central trial coordinator, who was accountable for assigning the envelope numbers on the operator’s request. Sequentially numbered opaque, sealed envelopes were used for concealed randomization of group allocation to minimize the risk of bias. Consolidated Standards of Reporting Trials study flow diagram is shown in Figure 2 . Participants could stop and exit the trial at any point of the study, and consecutive treatment would have ensued as standard orthodontic therapy.

Fig 2
Consolidated Standards of Reporting Trials 2010 study flow diagram.


It is not feasible to blind the participants and the operator during the intervention as it involves an additional procedure. However, the examiner assessing the study casts was blinded to the participant’s assigned intervention. Details of the patients were concealed and randomly renumbered by the central trial coordinator before the measurements. The principal investigator who conducted the measurements was unaware of treatment assignments for participants.

Interim analyses and stopping guidelines

Interim analyses were not applicable. The stopping rule will be applied when participants fail to attend at least 2 consecutive appointments. All clinical treatment will be continued as normal.

Statistical analysis (primary and secondary outcomes)

Data analysis was performed using the SPSS software (version 25.0; IBM Corp, Armonk, NY). The statistical significance level was prespecified at P <0.05 with 95% CI. Treatment duration to achieve alignment was assessed using the survival analysis log-rank (Mantel-Cox) test. Alignment rate ratios for group and LII level were calculated with Cox proportional hazards regression modeling.

Repeated measures analysis of variance was applied to evaluate the alignment improvement percentage. Intraexaminer reliability was performed to ensure the reliability of the data collection techniques using the intraclass correlation coefficient. The investigator performed measurements of the 15 dental casts in random order at 2-week intervals. Intraexaminer reliability for LII was excellent, with an intraclass correlation coefficient of 0.93.


Participant flow

Initial participants that were screened for this trial consisted of 35 patients. However, 5 patients were excluded: 3 declined to participate, whereas 2 moved away. Thirty participants who fulfilled the inclusion criteria were enrolled for the trial and continued to undergo follow-up appointments as per protocol. Later, 1 participant dropped out from the MOPs group because of pregnancy, and 1 was lost in the control group because the patient failed to attend follow-up records for 2 consecutive months.

Baseline data

Table I shows the participants’ demographic characteristics, displaying variables of age, sex, incisor relationship, and initial LII values. There was no significant difference in initial LII between groups ( P = 0.939).

Dec 24, 2021 | Posted by in Orthodontics | Comments Off on Effectiveness of microosteoperforations in accelerating alignment of maxillary anterior crowding in adults: A randomized controlled clinical trial
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