Introduction
The study aimed to evaluate and compare the effects of local platelet-rich fibrin (PRF) injection and piezocision applications on tooth movement during canine distalization, as well as to evaluate any changes in the periodontal parameters.
Methods
Twenty-four patients were randomly divided into 2 groups. A randomly selected side of the maxillary arch received either PRF injection (PRF group) or piezocision (piezocision group). The contralateral sides of both groups served as the controls. After piezocision and PRF injection applications, canine distalization was initiated in both groups with a 150 g force. Patients were followed every 2 weeks for a total 12 of weeks. The following variables were evaluated: cephalometric measurements, the amount of canine distalization, molar mesialization, canine rotation, transversal changes in dental models, and periodontal parameters.
Results
The amount of canine distal movement was found to be greater in the experimental sides than in the control sides in both groups at 12 weeks ( P <0.05). There were no differences in the amount of molar mesialization, canine rotation, or transversal measurements in both groups when compared with the experimental sides with the control sides ( P >0.05). There were no differences in the skeletal measurements or periodontal parameters in both groups ( P >0.05). In both groups, the maxillary incisors were retroclined and retracted.
Conclusions
PRF and piezocision accelerated tooth movement, but there were no differences between the 2 applications in terms of speed, amount, duration of tooth movement, or periodontal parameters during canine distalization.
Highlights
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Platelet-rich fibrin (PRF) and piezocision accelerated orthodontic tooth movement.
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PRF and piezocision applications did not differ in terms of orthodontic tooth movement.
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PRF and piezocision applications did not differ in terms of periodontal parameters.
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These techniques had no negative effect on periodontal health.
Orthodontic treatment aims to stably achieve appropriate esthetic with a corresponding occlusal relationship. The long duration of orthodontic treatment, especially for adult patients, may lead to their avoiding treatment or searching for alternatives to shorten the treatment period. Prolonged orthodontic treatment increases the risk of treatment-related complications, such as periodontal problems, external root resorption, and patient incompatibility.
Throughout the literature, electric current, magnets, lasers, mechanical vibrations, ultrasound, distraction, alveolar surgery of the interseptal bone, corticotomy, bone incision, and corticision techniques have been used to accelerate tooth movement.
Surgical methods are the most commonly used techniques in accelerating tooth movement. Changes in bone structure after corticotomy were first described by Frost as the regional acceleration phenomenon. On the basis of this phenomenon, it was thought that surgical methods could accelerate orthodontic tooth movement. The regional acceleration phenomenon is defined as a local remodeling process in which tissues undergo a regenerative process that is faster than their normal regeneration process against injurious stimuli.
Recently, Dibart et al introduced a new and minimally invasive technique called piezocision . First, vertical gingival incisions that are large enough to allow for the placement of piezoelectric surgery knives are applied to the buccal region between the roots of the teeth. Bone incisions are made at a depth of 3 mm, bypassing the periosteum through the incision area with a piezoelectric surgical knife without raising a flap.
Recent studies have been researching the effect of platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) on the rate of orthodontic tooth movement, finding that these techniques specifically have an accelerative effect.
PRP is defined as an autologous concentration of platelets in a small volume of plasma. PRP contains a high number of platelets, growth factors, and coagulation factors.
PRF has been defined as the second generation platelet concentration product developed by Joseph Choukroun in France. PRF is a fibrin structure obtained from natural blood and contains platelets and leukocytes. Unlike the PRP technique, anticoagulants and bovine thrombin, as well as calcium chloride, are not used in this technique. ,
In the literature, there have been no clinical studies examining the effect of I-PRF injection on orthodontic tooth movement during canine distalization and no studies comparing the effect of the PRF injection method with piezocision, which is a clinically preferred method.
This study aimed to evaluate the effects of local PRF injection and piezocision techniques on tooth movement during canine distalization and compare these effects with each other and the control group and evaluate changes in the periodontal parameters. The null hypothesis of our study is that there is no difference between local PRF injection and piezocision techniques during canine distalization in terms of the rate and acceleration of orthodontic tooth movement and periodontal parameters.
Material and methods
Approval for the study was obtained from the ethics committee presidency (2018/16) of the Clinical Research Ethical Committee of Selçuk University, Konya, Turkey. All patients and parents were informed of the PRF injection and piezocision applications and signed an informed consent form.
Sample size evaluation was based on the standard deviation of a similar study performed by Aksakalli et al (μ 1 , 2.90; μ 2 , 1.73; σ, 0.86) and the number of canine distalization differences between experimental and control groups in a similar study by Aksakalli et al. Assuming a clinically significant amount of canine distalization 1.2 mm differences, with an α error of 0.05 and a power of 90%, we calculated that the sample size should be 12 per group. Twenty-four patients with suggested orthodontic treatment plans requiring the therapeutic extraction of the maxillary first premolars and the subsequent distalization of the maxillary canines were selected for the study.
All patients fulfilled the following criteria: aged 14-22 years, Class II malocclusion with dentoalveolar protrusion or moderate crowding, no previous orthodontic treatment, no systematic disease or use of drugs, and no congenital tooth deficiency except the third molars in the maxilla. All patients also had permanent dentition and good oral hygiene with normal probing depth.
The patients were randomly divided into 2 groups. The randomization was performed via coin tosses to prevent selection bias. The study was planned using a split-mouth design. While the patients underwent mini screw-supported canine distalization on both sides of the maxillary arch, a randomly selected side of the maxillary arch received PRF injection in the PRF group and a piezocision technique in the piezocision group. The other side of the maxillary arch served as the control in both groups.
When the maxillary teeth were bonded, the maxillary first premolar teeth were extracted during the same appointment (T0). The initial phase of leveling and alignment was completed with 0.022 × 0.030-in slot MBT brackets (Discovery Smart; Dentaurum, Ispringen, Germany). Leveling was achieved using 0.014, 0.016, 0.016 × 0.016-in, and 0.016 × 0.022-in nickel-titanium archwires sequentially.
Miniscrews (MTN, Medifarm, Istanbul, Turkey; diameter, 1.6 mm; length, 10 mm) were placed under local anesthesia via the self-drilling method and then were placed bilaterally between the maxillary second premolar and the first molar for skeletal anchorage in both groups.
In the PRF group, PRF was injected submucosally under local anesthesia for pain control in the experimental sides. PRF was applied to 3 surfaces of the maxillary canine (buccal, palatal, and distal) 3 times (T0, T2, and T4). For the experimental sides, 0.7 mL of PRF was injected through the attached gingivae into the oral mucosa ( Fig 1 ).
The protocol for PRF preparation included the collection of venous blood from the vein using a 10 mL syringe. The collected blood was transferred to a sterile 9 mL PRF tube (White Cap IntraSpin PRF blood collection tube; Intra-lock, Salerno, Italy). A White Cap IntraSpin vacuum and anticoagulant-free injectable PRF blood collection tubes were used. The PRF tubes were immediately centrifuged at 800 rpm for 3 min, which resulted in the formation of 3 layers: a red blood cell layer at the bottom, a platelet-rich fibrin layer in the middle, and a platelet-poor plasma at the top. Approximately 2.1 mL of injectable PRF was taken by a 2.5 mL dental syringe from the PRF formed in the middle layer.
In the piezocision group, piezocision was performed at the experimental sides before canine distalization. After the application of local anesthesia, 2 vertical interproximal incisions were performed on the mesiobuccal and distobuccal sides of the maxillary canines using a number 15 blade without flap reflection. To preserve the interdental papillae, the incisions were performed 4 mm apical to the interdental papillae. A piezosurgery knife was used to create 3 mm-deep cortical alveolar incisions, which were not sutured after piezocision was performed ( Fig 2 ).
In both groups, a 0.016 × 0.022-in stainless steel archwire was ligated for canine distalization. After piezocision or PRF injection application, canine distalization was immediately and simultaneously initiated in the same mechanical experimental and control sides in both groups. Nickel-titanium closed coil springs (TruFlex, nickel-titanium closed coil springs 9 mm Med; Ortho Technology, Lutz, Fla) were stretched between the maxillary canine and miniscrews with 150 g force with force being calibrated every 2 weeks. The total follow-up period was 12 weeks after the start of canine distalization. The incisor teeth were ligated to each other during the follow-up period to prevent diastema between incisor teeth.
Orthodontic records (orthodontic models, photographs, lateral cephalometric and panoramic x-rays) and periodontal measurements were taken from patients at the onset of canine distalization (T0) and 12 weeks after the onset of canine distalization (T6). Before the lateral cephalometric x-ray was taken, 0.017 × 0.025-in stainless steel reference wires were ligated to the maxillary first molar tubes and the canine brackets. Straight reference wires were placed on the right side, whereas the helix reference wires were placed against the left side to avoid superposition. Orthodontic models were obtained from the maxillary arch every 2 weeks at 7-time points (T0, T1, T2, T3, T4, T5, and T6).
A software program (Quick Ceph Image; Quick Ceph Systems, San Diego, Calif) was used for the lateral cephalometric x-ray measurements ( Figs 3-5 ). The pterygoid vertical plane was perpendicular to the Frankfurt horizontal plane through the pterygoid and was used to measure the dentoalveolar parameters. The dental models were scanned using a 3 Shape E3 scanner (3SHAPE, Copenhagen, Denmark). The 3 Shape Ortho Analyzer software program was used for measurements of the digital dental models. The dental models were superimposed to compare the changes from T0 to T6. The medial end of the third palatal rugae and the incisive papilla were used for the superimpositions ( Fig 6 ), and these points have been used in similar research. , The amount of maxillary canine rotation, maxillary first molar mesialization movement, and maxillary canine distalization movement was evaluated in superimposed T0 and T6 dental model scans. Figure 7 shows the angular measurements for the amount of canine rotation in the digital dental model. Figure 8 , A and B , show the measurements of the amount of canine distalization and molar mesialization, respectively, in the digital dental model. The distances from the canine cusp tip to the median raphe (MR) and the first molar mesiobuccal cusp tip to the MR were measured to determine the transversal change between the T0 and T6 dental models’ scans ( Fig 9 ). The MR bilaterally passes through the contact point of the parallel rugae points, the incisive papilla, and the incisal midpoint, as described by Hoggan and Sadowsky. To assess periodontal health, a plaque index, gingival index, and probing depth were evaluated in the T0 and T6 dental models scans for the maxillary canine and all maxillary teeth. All procedures and measurements were undertaken by the same researcher (İ.Ç.K.).
Statistical analysis
The data were analyzed using SPSS software (version 21.0; IBM, Armonk, NY). A Kolmogorov Smirnov test was applied to the data to establish normality. The Wilcoxon test was used to compare 2 dependent groups, and a Mann-Whitney U test was used to compare 2 independent groups. Friedman test was used to evaluate repeated measurements. A chi-square test was used in the analysis of the categorical data. P <0.05 was considered statistically significant.
A lateral cephalometric x-ray and the digital dental model measurements of 12 randomly selected patients were remeasured by the same researcher (X.X) 2 weeks after the first measurements were taken to assess error analysis. Intraclass correlation coefficients were calculated to assess the reliability of the measurements. The results were found to be range from 0.956 and 0.999. All measurements were above the limit value of 0.700.
Results
This study was completed with 12 patients in the PRF group (7 girls, 5 boys; mean age, 16.45 ± 0.27 years) and 12 patients in the piezocision group (7 girls, 5 boys; mean age, 16.84 ± 0.33 years). There was no patient exclusion or loss during the study period. The analyses were performed for all patients. Participant flow throughout the study is shown in the Consolidated Standards of Reporting Trials diagram ( Fig 10 ).
At the beginning of the study, there was no statistically significant difference between both groups in terms of their initial measurements (T0) ( P >0.05). Homogeneous distribution of the patients was observed.
All skeletal measurements remained unchanged in both groups, and there was no significant difference in the skeletal parameters between the PRF and piezocision groups ( P >0.05) ( Table I ).
| Parameter | PRF | Piezocision | P value | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Mean | SD | Min | Max | Mean | SD | Min | Max | ||
| SNA (°) | 0.03 | 0.03 | −0.10 | 0.30 | 0.05 | 0.03 | −0.20 | 0.30 | 0.551 |
| SNB (°) | 0.04 | 0.03 | −0.20 | 0.20 | 0.00 | 0.05 | −0.40 | 0.20 | 0.799 |
| ANB (°) | 0.00 | 0.03 | −0.30 | 0.20 | 0.07 | 0.05 | −0.10 | 0.60 | 0.514 |
| Y-axis (°) | −0.11 | 0.19 | −1.50 | 0.60 | 0.56 | 0.42 | −2.40 | 3.70 | 0.114 |
| FMA (°) | 0.27 | 0.37 | −1.50 | 2.30 | 0.70 | 0.41 | −1.80 | 2.50 | 0.514 |
| SN-GoGn (°) | 0.32 | 0.50 | −2.40 | 2.80 | 0.71 | 0.41 | −1.70 | 2.30 | 0.514 |
| SN-PD (°) | 0.29 | 0.39 | −3.30 | 2.50 | 0.40 | 0.37 | −1.80 | 2.60 | 0.843 |
| Mx-Md (°) | 0.46 | 0.32 | −1.10 | 2.80 | 0.39 | 0.41 | −2.00 | 2.80 | 0.799 |
In both groups, the dentoalveolar measurements of the maxillary and mandibular incisors decreased, but the interincisor angle increased 12 weeks after the onset of canine distalization (T6). As a result, the maxillary and mandibular incisors were retroclined and retracted in both groups. When the dentoalveolar measurements of the incisors were compared, U1-NA (°) and SN-U1 (°) values, a statistically significant difference was found between the groups ( P <0.05) ( Table II ).
| Parameter | PRF | Piezocision | P value | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Mean | SD | Min | Max | Mean | SD | Min | Max | ||
| SN-U1 (°) | −2.42 | 0.66 | −8.90 | −0.80 | −5.30 | 1.05 | −11.90 | −1.10 | 0.024 ∗ |
| U1-PD (°) | −2.03 | 0.79 | −8.10 | −0.20 | −4.26 | 1.12 | −10.80 | −0.70 | 0.078 |
| U1-NA (mm) | −1.32 | 0.32 | −3.70 | 0.00 | −2.54 | 0.47 | −5.60 | −0.90 | 0.060 |
| U1-NA (°) | −2.45 | 0.68 | −9.10 | −0.60 | −4.83 | 1.08 | −12.00 | −1.10 | 0.045 ∗ |
| U1-PD (mm) | −0.65 | 0.24 | −2.70 | 0.20 | −0.02 | 0.44 | −3.30 | 2.20 | 0.266 |
| U1-PTV (mm) | −1.10 | 0.32 | −3.50 | 0.50 | −2.35 | 0.46 | −5.30 | −0.30 | 0.052 |
| L1-NB (mm) | −0.45 | 0.27 | −1.70 | 2.00 | −0.70 | 0.22 | −2.20 | 0.20 | 0.887 |
| IMPA (°) | −2.69 | 0.61 | −6.20 | −0.50 | −1.83 | 0.40 | −4.80 | 0.00 | 0.443 |
| L1-NB (°) | −2.58 | 0.70 | −6.80 | 0.90 | −1.20 | 0.36 | −2.90 | 0.40 | 0.160 |
| L1-APg (mm) | −0.43 | 0.22 | −1.40 | 1.70 | −0.58 | 0.15 | −1.50 | 0.10 | 0.932 |
| Interincisor angle | 4.70 | 0.92 | −0.40 | 8.50 | 5.88 | 1.01 | 1.30 | 11.70 | 0.755 |
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