Extraction Of Maxillary First Premolars Research Articles

Effect of laser corticotomy on canine retraction rate: a split-mouth randomized clinical trial

BackgroundThis study assessed the effect of corticotomy with Er: YAG (erbium-doped yttrium aluminium garnet) laser on the rate of canine retraction.MethodsThis randomized split-mouth controlled clinical trial was conducted on 12 patients undergoing orthodontic treatment with extraction of maxillary first premolars. Following initial leveling and alignment, an alginate impression was made from the maxillary arch, and Er: YAG laser corticotomy was performed in one of the maxillary quadrants of each patient. Canine retraction was started immediately after corticotomy by placement of nickel-titanium (NiTi) closed coil springs at both sides. At the end of each month, alginate records were repeated for 4 months. Study models were scanned, and the anteroposterior movement of canine was quantified bilaterally. Pain was also measured by a visual analog scale (VAS). Probing depth (PPD) of canines and two adjacent teeth was also evaluated and pulp vitality was assessed by performing the cold test. Data were analyzed by paired and independent t-test and one-way ANOVA (alpha = 0.05).ResultsThe rate of canine retraction was significantly greater in the laser-assisted corticotomy quadrant than the control (P < 0.05). No significant difference existed in posterior anchorage loss, canine rotation angle, PPD, pulp vitality, or pain score between two groups (P > 0.05).ConclusionsFlapless Er: YAG laser corticotomy significantly enhanced canine retraction rate with no adverse effect on other parameters.

Comparison of GUMMETAL® and stainless steel alloy during canine retraction: A pilot split-mouth randomized controlled trial

A TiNb alloy wire (GUMMETAL® [GM], Toyota Central R&D Labs, Inc., Nagakute, Japan) was recently developed with unique properties for orthodontic applications. This pilot split-mouth randomized controlled trial compared maxillary canine retraction during space closure using sliding mechanics on GM vs. stainless steel (SS) archwires. Subjects who met the inclusion criteria were treated with fixed appliances and maxillary first-premolar extractions between September 2020 and March 2022. After leveling and aligning, maxillary archwires, fabricated by crimping together segments of 0.016×0.022" GM and SS archwires, were placed and canine retraction initiated using nickel-titanium coil springs. Digital models of the maxillary arch were superimposed at 0, 4, 8 and 12 weeks and the amount of canine movement (mm), rate of movement (mm/month), and 3-dimensional changes (rotational, vertical extrusion, tip) were measured and compared statistically. Of the 12 subjects recruited, only six completed the study with a median age of 15.8 years (12.0-17.4 years). At 12 weeks, the median canine retraction was 3.41mm (IQR: 2.10, 4.76) with GM versus 3.71mm (IQR: 1.62, 6.45) with SS. The retraction rate was 1.14mm/month (IQR: 0.69, 1.59) with GM, versus 1.24mm/month (IQR: 0.54, 2.15) with SS. The median rotational, vertical and tip changes of the canine were 7.90̊, 0.59mm and 6.15̊ with GM, and 7.25̊, 0.29mm and 2.05̊ with SS. Intergroup differences with all measurements were not statistically significant. No significant differences were found between GM and SS during maxillary canine retraction. GM demonstrated clinical potential for space closure mechanics, however, future larger studies are needed.

Effectiveness of Flapless Cortico-Alveolar Perforations Using Mechanical Drills Versus Traditional Corticotomy on the Retraction of Maxillary Canines in Class II Division 1 Malocclusion: A Three-Arm Randomized Controlled Clinical Trial.

Both invasive and minimally invasive surgical methods have recently gained popularity in accelerating orthodontic tooth movement. Traditional corticotomy (TC) was one of the first effective invasive surgical techniques in shortening orthodontic treatment time, whereas the flapless cortico-alveolar perforations (FCAPs) technique is a modern minimally invasive method that has recently shown good results in different types of orthodontic tooth movement. Therefore, this study aimed to compare the effectiveness of TC versus FCAPs in maxillary canine retraction when treating Class II division 1 malocclusion patients. This was a single-blinded, single-center, three-arm randomized controlled trial. A total of 51 patients (22 males, 29 females, mean age 20.98 ± 1.95) whose treatment planning included the extraction of maxillary first premolars were enrolled and randomly divided into three groups: the TC group, the FCAPs group, and the control group. The assessed outcomes were the amount of canine retraction, anchorage loss, and canines' rotation, which was evaluated at five-time points till the completion of canine retraction. There were statistically significant differences in the amount of canine retraction between the three groups in the first two months (p < 0.001), with greater mean values in the TC group (p < 0.001) in the first month. However, the amount of canine retraction in the FCAPs group was significantly greater in the second month compared to the TC group (p = 0.003) and the control group (p < 0.001). In the first month of canine retraction, anchorage loss, and canine rotation were significantly lesser in the TC and FCAPs groups than in the control group (p < 0.001). On the contrary, the canines' rotation amount after the completion of retraction was greater in the TC group than in the other two groups (p < 0.001). TC and FCAPs are efficient adjunctive surgical methods for accelerating canine retraction. At the end of the first month, the TC accelerated canine retraction by 59.85% and FCAPs by 44% compared to the conventional retraction. At the end of the second month, the acceleration was less than recorded in the first month (35.44% and 50.20%, respectively).The acceleration effect of the surgical interventions appeared transient and did not last in the following observation period.

Effect of leukocyte platelet-rich fibrin on the rate of canine movement – A prospective and randomized control trial

Objectives: The present study was conducted to investigate the effects of leukocyte and platelet-rich fibrin (L-PRF) on the rate of maxillary canine retraction for a period of 5 months. Material and Methods: A split-mouth study was conducted on 16 patients (32 extraction sockets) (Nine males and seven females; age ranging 17–25 years) with Class II Div 1 malocclusion or Class I bimaxillary protrusion, requiring therapeutic extraction of bilateral maxillary first premolars. After the initial leveling and alignment, L-PRF plugs were placed immediately in the randomly selected socket (Experimental Group) and the other side served as control for secondary healing (Control Group). This was followed by the activation of nickel-titanium closed coil springs for canine retraction. The rate of canine movement, canine rotation, tipping, root resorption, and molar movement was assessed at monthly intervals for 5 months (T0–T5). Data were collected from study models. Assessment of pain accompanying the procedure was done using a Likert scale. The trial was registered at the Clinical Trials Registry of India (REF/2022/02/051837). Results: The study revealed that there was a significant increase in the rate of canine movement on the experimental side in the first 2 months and significant molar anchorage loss was seen only in the 1st month. There were statistically non-significant differences in canine rotation, tipping, probing depth, root resorption, and pain perception between the groups. Conclusion: The use of L-PRF plugs in the extraction sockets enhanced the rate of canine movement in the first 2 months of treatment with less anchorage loss and no deleterious effects on periodontium.

Pulp Vitality of Orthodontic Retracted Canine Using Two Approaches of Periodontal Distraction: A Comparative Clinical Study

Objectives: All studies performed periodontal distraction with interseptal bone cuts but no one performed it without interseptal bone cuts. Therefore the aim of the present study was to evaluate and compare the effect of periodontal distractor with and without interseptal bone cuts on the pulp vitality of the retracted canines. Methods: The sample of the study consisted of 32 canines in 16 female patients (16- 21 years old) requiring extraction of bilateral maxillary first premolars and canine retraction. They were divided into two groups: canine retraction by periodontal distractor with distal interseptal bone cuts (Group I), canine retraction by periodontal distractor without distal interseptal bone cuts (Group II). After bilateral maxillary premolar extraction in both groups inter septal bone cuts was done in group I only. Then the periodontal distractor was cemented and activated twice per day in both groups. An electrical vitality test was evaluated before and after the distraction procedure. Results: None of the teeth reacted negatively to the electrical vitality test that was performed one month after the completion of the distraction procedure. There was no clinical sign of discoloration or pulpal pain in any tooth. Conclusions: Canine retraction was accelerated effectively by periodontal distraction technique either with or without distal interseptal bone cuts. The electrical pulp tester was positive in both groups.

Comparative treatment outcomes after bilateral extractions of maxillary second molars or first premolars in patients with class II malocclusion: a retrospective study

BackgroundThis retrospective cohort study aimed to compare treatment results between bilateral extraction of upper second molars (M2) and first premolars (P1) in terms of treatment timing, cephalometry, upper third molar alignment and relapse in the long-term.MethodsFifty-three consecutively treated Caucasian patients with a brachyfacial pattern, skeletal class I and dental class II requiring extraction in the maxilla due to crowding were retrospectively divided into group I (M2 extracted; N = 31) and II (P1 extracted; N = 22). Fixed appliances were inserted after extraction and after distalisation of the first molars in group I. Post-treatment lateral cephalograms were digitally analysed and compared between groups. Six to seven years later relapse and success of upper third molar alignment were clinically evaluated as well as orthodontic treatment duration, pre-treatment age and gender recorded.ResultsAfter debonding patients with second molar extraction showed significantly smaller values for the Wits-appraisal, but higher values for index and facial axis. Extracting first premolars caused significantly more retroinclination/−position of anterior teeth and an increased profile concavity, more relapse and less successful alignment of upper third molars. Orthodontic treatment duration, pre-treatment age and gender were not significantly different between groups.ConclusionsBilateral extraction of upper first premolars or second molars may solve dental crowding in skeletal class I dental class II patients with a brachyfacial growth pattern. Upper second molar extraction seems to affect maxillary third molar alignment, long-term stability and dental and soft-tissue cephalometric parameters positively, but no intervention proved to be clearly superior.

Comparison of Maxillary Canine Retraction Using Split-Mouth Design With Dual Force Cuspid Retractor and T-loop Segmental Arch: A Split-Mouth Randomized Clinical Trial.

Introduction This study was designed to explore the differences between two frictionless mechanics for canine retraction i.e., dual force cuspid retractor and T-loop segmental arch. T-loop for canine retraction creates a biomechanical system to deliver a predetermined force and a relatively constant moment-to-force ratio whereas dual force cuspid retractor uses power arms on buccal as well as palatal aspects for canine retraction. Bodily tooth movement can be achieved by both methods, but in this study, our main focus was to reduce the canine retraction timing with better three-dimensional control. Method This split-mouth study was conducted on a total of 20 cuspids of ten patients (five male and five female). Where one side of the arch was selected for T-loop and the other side for dual force cuspid retractor, randomly. Inclusion criteria for this study were; no congenitally missing teeth (excluding third molar), class I or class II molar relationship, no previous history of orthodontic treatment, good oral periodontal status, patients in whom extraction of maxillary first premolar during treatment was indicated. Both groups were compared for the duration of canine retraction, anchorage loss; tipping, and rotation of cuspid and molar, individually, after retraction. Result The result of this study showed that the duration of canine retraction was significantly less in group one, i.e., dual force cuspid retractor 73.8 ± 12.38 days, than in group two, i.e., T-loop 109.4 ± 16.71 days. The anchorage loss in group one was 0.60 ± 0.61 mm and that in group two was 2.40 ± 0.87 mm. Also, the amount of tipping and rotation of the cuspid and molar individually was significantly lesser in group one than in group two. Conclusion In this study, the dual force cuspid retractor shortens the duration of canine retraction with better three-dimensional control and better anchorage preservation when compared to T-loop.

Comparison of the temperature changes in pulp using monophasic light-emitting diode curing unit at different exposure times: An in vivo study

This invivo study evaluated the temperature changes in the pulp chamber at different exposure times using a monophasic light-emitting diode curing unit. Forty-five patients (aged 13-25 years) requiring extraction of maxillary first premolars for orthodontic reasons were included in the study. After access opening, the temperature rise was recorded when exposed to monophasic light-emitting diode curing light (Elipar 3M ESPE; Pymble, New South Wales, Australia) at 5, 10, 15, and 20 seconds with K-type thermocouple probe. Teeth were atraumatically extracted on the same day. The results were analyzed with an analysis of variance and the Bonferroni test. There was a significant increase of 2.1°C ± 0.5°C of pulpal temperature in the maxillary first premolar tooth during exposure to a light curing unit from baseline to 20 seconds. The mean baseline temperature was 35.7°C ± 0.52°C. The highest mean temperature was recorded at 20 seconds (37.8°C ± 0.57°C), and the lowest mean temperature was recorded at 5 seconds (36.1°C ± 0.61°C). There were significant differences among each group (P<0.001) with a mean increase in pulpal temperature from baseline to exposure mode of 5, 10, 15, and 20 seconds. The study results reveal a statistically significant increase in pulpal temperature with a monophasic curing light, which can be used for up to 20 seconds without causing any detrimental effects on the pulp.

The effect of maxillary first and mandibular second premolar extractions on the posterior Bolton ratio

The anterior and overall Bolton ratios and their application in orthodontics are widely known. However, little has been reported about the posterior Bolton ratio, how it is affected by the extraction of posterior teeth, and its application in orthodontic treatment planning. This study aimed to investigate how extracting maxillary first and mandibular second premolars affects the posterior Bolton ratio. The sample included 55 patients with Class I occlusion within 1 standard deviation of ideal anterior and overall Bolton ratios. The digitized models were subjected to virtual extraction of maxillary first premolars and mandibular second premolars and setup of posterior teeth in ideal occlusion. If space closure compromised occlusion, the teeth were moved to achieve ideal cusp-fossa or cusp-marginal ridge occlusion. The ideal setups were measured for residual interproximal spacing. Statistical analysis used R statistical software (version 2018; R Core Team, Vienna, Austria). The ideal nonextraction posterior Bolton ratio was determined from the sample to be 105.77 ± 1.99%. The ideal expected posterior Bolton ratio for maxillary first and mandibular second premolar extraction patients was 106.52 ± 2.52%. This significantly differed from the expected posterior Bolton ratio for the 4 first premolar extractions. Patients finished with an average of 1.28 mm net residual spacing between mandibular first premolars and first molars; 38.2% of patients finished with at least 1.5 mm of residual space, and 9.1% of patients finished with at least 2 mm of residual space. A patient with ideal anterior, posterior, and overall Bolton ratios treated with maxillary first and mandibular second premolar extractions to ideal occlusion will likely finish with some spacing in the mandibular dentition.

Non-Surgical Treatment of Class II Division 1 Malocclusion in an Adult Patient with a Missing Lower Lateral Incisor Tooth: A Case Report

Class II Division 1 malocclusion is clinically more widespread than any other form of malocclusion and can be managed in a variety of ways, taking into account variables such as patient compliance, age, and anteroposterior disparity. Orthodontic camouflage treatment, aimed at masking the underlying skeletal discrepancy, is an acceptable option for most patients. This typically involves the extraction of two maxillary premolars in cases without mandibular arch crowding, or the extraction of two maxillary and two mandibular premolar teeth when crowding is present. The present case report aimed to discuss the successful treatment of a unique case involving a 19-year-old adult female patient with Class II Division 1 malocclusion, a missing mandibular left lateral incisor, and an overjet of 7 mm. Since the patient declined surgical and prosthetic treatment, an alternative, novel, and unorthodox method of camouflage treatment was employed, which involved the extraction of maxillary first premolars combined with symmetrical incisor space closure. The achieved treatment outcomes included a functionally and aesthetically acceptable occlusion, reduced overjet, and an improved soft tissue profile.

Does leukocyte-platelet-rich fibrin (L-PRF) cause long term acceleration in the rate of canine retraction? A split-mouth, two-arm parallel group, randomized control trial

ABSTRACT Objective: The present study was conducted to investigate the effects of leukocyte-platelet-rich fibrin (L-PRF) on the rate of maxillary canine retraction for a period of 5 months. Methods: A split-mouth study was conducted on 16 subjects (9 males and 7 females; age range 17-25 years; mean age, 21.85±2.45 years) who required therapeutic extraction of bilateral maxillary first premolars. After the initial leveling and alignment, L-PRF plugs were placed in a randomly selected extraction socket (Experimental Group), and the other side served as a control (Control Group). Canine retraction was carried out by the activation of nickel-titanium (NiTi) closed-coil springs delivering 150 g of force. The rates of canine movement, canine rotation, tipping, root resorption, and molar movement were assessed at monthly intervals for five months (T0-T5). Pain, swelling and discomfort accompanying the procedure were assessed using a Likert scale. Results: The study revealed a significant increase in the rate of canine movement on the experimental side in the first two months, and significant molar anchorage loss was observed only in the first month for control side. There were no statistically significant differences between the groups regarding canine rotation, tipping, probing depth, root resorption, and pain perception. Conclusions: The use of L-PRF plugs in extraction sockets considerably enhanced the rate of canine movement only in the first two months, and long-term efficacy was not observed in this study.

Evaluation of the Effect of Two Different Activation Protocols of Periodontal Distractor on the Periodontal Health after Rabid Canine Retraction

Aim: To evaluate the effect of two different activation protocols of periodontal distractor on periodontal health after rabid canine retraction. Objectives: 1) to evaluate the periodontal health of two activations/day of periodontal distractor. 2) To evaluate the periodontal health of four activations/day of periodontal distractor. 3) To compare between two different activation protocols of periodontal distractor on periodontal health. Methods: The study was carried out on 32 canine of 16 female patients (16-22 years of age) requiring extraction of bilateral maxillary first premolars and maximum anchorage. They were divided into two groups. (Group I): Canine retraction was done by periodontal distractor with twice activations per day. (Group II): Canine retraction was done by periodontal distractor with four activations per day. Periodontal distractor was cemented after bilateral maxillary premolar extraction and inter septal bone corticotomy was done. The periodontal health of maxillary canines was evaluated using these parameters before and after retraction: (gingival index, periodontal index and probing depth). All data were explored for normality by using Shapiro Wilk and Kolmogorov Normality test which revealed that all data originated from non-parametric data. Results: for periodontal index and probing depth there was insignificant difference between them in before and after in both groups. For gingival index there was insignificant difference between them in before, while in after group II was significantly higher than group I. Conclusion: In this study, there was increase in all periodontal health parameters including (gingival index, periodontal index and probing depth) after using of periodontal distractor with both protocols of activations denoting gingivitis. The 2 activations/day was better than 4 activations/day for periodontal health during canine retraction by periodontal distractor.

Effect of Virtual Reality Distraction on Pain Perception, Anxiety and Hemodynamic Changes during Therapeutic Extraction of Bilateral Maxillary First Premolars Split-Mouth Technique

Aim: The aim of the study is to assess the effect of virtual reality distraction on pain and anxiety during therapeutic extraction of bilateral maxillary first premolars. Design: Non Randomized prospective split mouth technique requiring therapeutic extraction of bilateral maxillary first premolars. Setting: All patients reporting to the department of OMFS Indira Gandhi dental college and hospital Pondicherry requiring therapeutic extraction of bilateral maxillary first premolars. Participants: Covering 56 patients requiring therapeutic extraction of bilateral maxillary first premolars who meets the inclusive and exclusive criteria. Main Outcome Measures: Anxiety is measured using Likert scale, vitals using sphygmomanometer and pulse oximeter. Results: Parameters analysed using T-test, there is subsequent reduction of Systolic blood pressure, respiratory rate and pulse rate using virtual reality distraction when compared to without virtual reality distraction except for diastolic blood pressure. Conclusion: By distracting the attention of the patient, pain and anxiety levels of the patients can be reduced and producers can be done smoothly according to our study results.

Effect of lip thickness and competency on soft-tissue changes

Improvement in facial esthetics is a major reason for seeking orthodontic treatment. Soft tissues responsible for esthetics show a variable response to the movement of underlying teeth during orthodontics. The purpose of this cross-sectional study was to analyze the response of soft tissues and compare it among groups presenting with different lip thickness and competence. It was carried out on 37 patients with Class I and Class II Division 1 malocclusion who had undergone extractions of maxillary first premolars and had completed their orthodontic treatment. Data were obtained by corresponding lateral cephalometric radiographs taken before and at the end of orthodontic treatment. Association was analyzed with a Pearson correlation test. Differences among groups exhibiting varying competency and lip thickness were tested with an independent sample t test. A P value of≤0.05 was considered statistically significant. Pearson correlation revealed significant associations among incisor tip retraction with lip base retraction (r= 0.68), lip base thinning (r= 0.41) and vermilion retraction (UV) (r= 0.73). Regression analysis showed a moderate increase in lip length (AB) and thickness at vermilion, which were 0.11 mm and 0.15 mm for each mm of incisor retraction at the tip, whereas stronger effects were observed for UV (0.38 mm) and lip base retraction (0.55 mm). There was significantly more lip base thinning (P= 0.03) and UV (P= 0.04) in the incompetent group compared with the competent group. The AB increased significantly in the sample with thicker lips (P= 0.01). Pearson correlation coefficient showed a strong association of lip retraction at the base and vermilion with the incisor movement at the cervical area, for competent and incompetent lips, and thicker and thinner lips. Lip retraction at vermilion and lip base thinning was significantly more in patients with incompetent lips, whereas the AB increased significantly more in the group with thicker lips.

The influence of two photobiomodulation protocols on orthodontically induced inflammatory root resorption (a randomized controlled clinical trial)

BackgroundControversial results have been reported regarding the impact of photobiomodulation (PBM) on orthodontically induced inflammatory root resorption (OIIRR). The aim of this study was to evaluate the influence of two PBM protocols, one of them requiring a high application frequency (on days 0, 3, 7, 14, then every 2 weeks), while the second requires less frequent applications (every 3 weeks), on OIIRR accompanying orthodontic treatment.MethodsTwenty female patients were recruited for this randomized controlled trial, requiring the therapeutic extraction of maxillary first premolars, and they were randomly divided into 2 equal groups. In Group A, one side of the maxillary arch randomly received PBM on days 0, 3, 7, 14, and every 2 weeks thereafter, while in Group B, one side was randomly chosen to receive PBM every 3 weeks. The laser applied was a Diode laser with a wavelength of 980 nm, in a continuous mode. Canine retraction in both groups was carried out using closed-coil springs, delivering 150 g of force, and the force level was checked every 3 weeks, over a 12-week study period. Pre-retraction and post-retraction cone-beam computed tomography (CBCT) was done for the evaluation of OIIRR.ResultsNo significant differences in the amount of OIIRR have been reported between the laser and control sides in both groups A and B. Also, no significant differences have been reported between the laser sides in both groups.ConclusionsPhotobiomodulation does not affect OIIRR, whether by increasing or decreasing its occurrence, with both laser application protocols. Therefore, it can be stated that PBM does not result in root resorption less than the commonly observed range elicited with conventional orthodontic treatment, and that it has no effect on OIIRR.Trial registration Two Low-level Laser Irradiation Protocols on the Rate of Canine Retraction (NCT04926389), 15/06/2021—retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT04926389.

Collection, Storage and Protein Extraction Method of Gingival Crevicular Fluid for Proteomic Analysis

Gingival crevicular fluid (GCF) may reflect the events associated with orthodontic tooth movement. Attempts have been conducted to identify biomarkers reflecting optimum orthodontic force, unwanted sequallea (i.e. root resorption) and accelerated tooth movement. The aim of the present study is to find out a standardized GCF collection, storage and total protein extraction method from apparently healthy gingival sites with orthodontics that is compatible with further high-throughput proteomics. Eighteen patients who required extractions of both maxillary first premolars were recruited in this study. These teeth were randomly assigned to either heavy (225g) or light force (25g), and their site specific GCF was collected at baseline and after 1hr, 1day, 7days, 14days, 21days and 28days post force application. Periostrips were used for GCF collection and subsequent phosphate buffered saline (PBS) was used for immediate protein elution with centrifugal speed of 10000rpm for 5min and stored at -80°C. Protein concentration was estimated using Bradford colorimetric assay. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was carried out to resolve the purity of proteins in the collected samples and the method of collection was validated by western immuno-blotting of alpha amylase salivary enzyme. The current collection, storage and protein extraction protocol showed the best protein recovery and purity with validated collection free of salivary contamination. In conclusion, tiny GCF volume from healthy sites and evaporation issues of such promising non-invasive fluid motivate us to investigate a standardized protocol enabling optimal preservation of GCF sample and the currently followed protocol may serve as a reference for future proteomic studies searching for GCF biomarkers in diagnosing and monitoring orthodontic tooth movement.

Three-dimensional comparison of the effects of sliding mechanics in labial and lingual orthodontics using the finite element method

The extraction of maxillary first premolars is usually the treatment of choice to resolve crowding, alveolar protrusion, or Class II malocclusion. The demand for a lingual orthodontic treatment is increasing because of its esthetic value; therefore, understanding lingual biomechanics is essential to every clinician. This study compared the 3-dimensional (3D) effects of sliding mechanics in labial and lingual orthodontics using the finite element method. Twelve 3D finite element models were created with different power arm heights and miniscrew positions. A 150 g of retraction force was applied from the head of the miniscrew to the power arm. The 3D displacement of the original nodes was measured, and the stress distribution on defined element zones of the periodontal ligament. Different force directions led to different movement patterns and stress distribution. The lingual models showed a more important lingual crown tipping, extrusion, and higher stress values than the labial models. Results were not affected by the vertical position of the miniscrew. Bodily en-masse retraction was not achieved in all models. Adding extra torque to the archwires is essential to prevent excessive lingual crown tipping. The lingual appliance induced more lingual tipping and extrusion of the anterior teeth. Expanding the archwire is important to minimize the risk of intercanine width reduction. The vertical position of the miniscrew does not affect the results of en-masse retraction.

Effect of micro-osteoperforations on the rate of orthodontic tooth movement and expression of biomarkers: a randomized controlled clinical trial.

ABSTRACTIntroduction: Micro-osteoperforation is a minimally invasive technique that has been used to accelerate orthodontic tooth movement and reduce treatment duration. However, literature presents conflicting reports about this technique. Objective: To evaluate the effectiveness of micro-osteoperforations on the rate of canine retraction and expression of biomarkers in gingival crevicular fluid (GCF). Methods: This was a randomized clinical trial with split-mouth study design. Thirty adult subjects with age above 18 years (20.32 ± 1.96) who required fixed orthodontic treatment and extraction of maxillary first premolars were enrolled and randomly allocated to either the experimental or control group. Randomization was performed by block randomization method, with a 1:1 allocation ratio. The experimental group received three micro-ostoperforations (MOPs) distal to maxillary canine, using the Lance pilot drill. The retraction of maxillary canine was performed with NiTi coil-spring (150g) in both experimental and control groups. The primary outcome was the evaluation of canine retraction rate, measured on study models from the baseline to 16 weeks of canine retraction. Secondary outcomes were the estimation of alkaline and acid phosphates activity in GCF at 0, 1, 2, 3, and 4 weeks. Results: There was a statistically significant difference in the rate of canine retraction only after the first 4 weeks. Subsequently there was no statistically significant difference from the eighth to the sixteenth weeks between MOPs and control group. There was a statistically significant difference in alkaline and acid phosphates activity in GCF between MOPs and control groups during the initial 4 weeks of canine retraction. Conclusion: Micro-ostoperforation increased the rate of tooth movement only for the first 4 weeks; thereafter, no effect was observed on the rate of canine retraction during 8, 12 and 16 weeks. A marked increase in biomarker activity in the first month was observed.

Efficacy of micro-osteoperforation of the alveolar bone by using mini-screw for acceleration of maxillary canine retraction in young adult orthodontic patients: A split-mouth randomized clinical trial

Acceleration of orthodontic tooth movement (OTM) can decrease the rate of complications. This study aimed to assess the efficacy of micro-osteoperforation (MOP) of the alveolar bone for acceleration of OTM by using mini-screws. This split-mouth randomized clinical trial evaluated 25 patients (11 females, 14 males, 16-25 years) with class II division I malocclusion who required canine retraction following the extraction of maxillary first premolar. The patients received similar orthodontic treatment at both sides with MOP on one side (MOP group) and no MOP on the other side (control side). Allocation of MOP to the side of jaw was random using Random Allocation Software in 1:1 distribution and equal numbers. Blinding was not applicable. The rate of canine movement was measured monthly for 5 months and considered as the main outcome. The degree of canine tipping was measured at the end of the intervention as the secondary outcome. All measurements were repeated for 12 patients by the two observers and the intra- and inter-examiner correlation coefficients were found to be 0.946 and 0.925, respectively. Data were analysed by paired t-test and repeated measures ANOVA. Twenty-five patients (11 females, 14 males, 16-25 years) were evaluated. No significant difference was found between the two groups at different time points in the rate of canine movement (P>0.05). The degree of canine tipping in the MOP group was significantly lower than that in the control group (5.34±3.11° versus 7.08±3.70°; P=0.040). Gender had no significant effect on OTM in any group (P>0.05). MOP could not accelerate canine retraction but decreased the degree of canine tipping.

The effect of piezocision vs no piezocision on maxillary extraction space closure: A split-mouth, randomized controlled clinical trial

The aim of this 2-arm-parallel, split-mouth trial was to investigate the effects of piezocision compared with no piezocision on maxillary canine distalization and to evaluate patient perceptions on the surgical procedure. Twenty-two participants requiring extractions of maxillary first premolars were recruited from the Department of Orthodontics (Sydney Dental Hospital) waiting list. After leveling and alignment, a minimum of 3mm space was required for canine retraction. Piezocision cuts distal to the canines were 4mm long and 3mm deep into the buccal cortical plate. The canine retraction was initiated on both sides immediately after surgery, with coil springs delivering 150g of force per side. Random assignment of piezocision or control intervention on the patient's right side was performed (www.randomisation.com) for the random number generation, and allocation concealment was accomplished with opaque, sealed envelopes. Patients were assessed every 6weeks for coil activation and alginate impressions over 18weeks. The primary outcome was the amount of tooth movement in mm. Secondary outcomes were canine rotation, anchorage loss measured on scanned dental models, and patient pain levels and perception on piezocision using visual analog scale questionnaires. Blinding was feasible for the dental model measurements. Twenty patients completed the trial. The treatment×time interaction showed no statistically or clinically significant differences in maxillary extraction space closure (b=-0.02; 95% confidence interval [CI], -0.29 to 0.25; P=0.89) canine rotation (b=-1.45; 95% CI, -4 to 1.09; P=0.26) and anchorage loss (b=-0.02; 95% CI, -0.38 to 0.34; P=0.92). All patients except for one had minimal pain associated with the piezocision surgery but found the procedure tolerable and would recommend it. No harm occurred during the trial. Piezocision-assisted maxillary canine distalization was similar to distalization with conventional orthodontics with patients tolerating the procedure.