Friction versus frictionless mechanics during maxillary en-masse retraction in adult patients with Class I bimaxillary dentoalveolar protrusion: a randomized clinical trial.

BACKGROUND: Extraction space closure is a challenging phase during orthodontic treatment that affects not only the total treatment duration but also the whole treatment outcome. OBJECTIVE: To compare the efficiency of friction and frictionless mechanics during en-masse retraction of maxillary anterior teeth in adult patients with bimaxillary dentoalveolar protrusion. TRIAL DESIGN: Two-arm parallel group, single-center randomized clinical trial. MATERIALS AND METHODS: Thirty-two adult patients with bimaxillary protrusion were recruited and randomly allocated to two different retraction mechanics. A friction group, using NiTi coil springs and a frictionless group using closing T-loops for en-masse retraction. Randomization in a 1:1 ratio was generated by Microsoft Excel. The randomization numbers were secured in opaque sealed envelopes for allocation concealment. Retraction started in all patients following first premolars extraction using miniscrews as a source of indirect anchorage. Activation was done on a monthly basis until complete retraction of anterior segment. The rate of retraction, amount of anchorage loss, the dental, and soft tissue changes were analyzed on digital models and lateral cephalograms taken before retraction and after space closure. BLINDING: The outcome assessor was blinded through data concealment during assessment. RESULTS: Two patients were lost to follow up, so 30 patients completed the trial. The rate of anterior segment retraction was 0.88 ±â€…0.66 mm/month in the frictionless group compared to 0.72 ±â€…0.36 mm/month in the friction group which was statistically significant. Anchorage loss of 1.18 ±â€…0.72 mm in the friction group compared to 1.29 ±â€…0.55 mm in the frictionless group with no significant difference. Comparable dental and soft tissue changes following en-masse retraction were reported in both groups, with no statistically significant difference. HARM: one patient complained of soft tissue swelling following miniscrew insertion, but the swelling disappeared after one week of using mouth wash. LIMITATION: The study focused only on the maxillary arch. CONCLUSION: Both mechanics have successfully achieved the required treatment objectives in patients with bimaxillary dentoalveolar protrusion. Frictionless group showed a faster rate of retraction than the friction group, which was statistically but not clinically significant. TRIAL REGISTRATION: Clinicaltrials.gov with the identifier NCT03261024.

Evaluation of the aesthetics and clinical findings in patients with missing maxillary lateral incisors treated with a 10-year interval.

INTRODUCTION: The most common treatment approaches for patients missing maxillary lateral incisors are implant replacement (IT) and orthodontic space closure (SC). Treatment techniques change and improve over time, and it is of interest to know if improvements differ between the methods. AIM: To compare the aesthetic outcome and other clinical findings in patients with one or two missing maxillary lateral incisors who were treated with a 10-year difference in time, with either orthodontic space closure or implant replacement. MATERIAL AND METHODS: A total of 88 patients were included in the study. Forty-four patients treated between 2011 and 2018 were included as the latter cohort (LC). The LC was compared to the early cohort (EC; n = 44), treated between 2001 and 2008. A total of 132 teeth was analysed: 62 teeth in the EC (28 teeth in IT cases and 34 teeth in SC cases) and 70 teeth in the LC (34 teeth in IT cases and 36 teeth in SC cases). Long-term clinical and aesthetic outcomes were evaluated. RESULTS: An improvement over time was found in crown length, BoP, papilla, the inclination of incisors, and overall appearance in IT cases and in crown colour and overbite in SC cases. A deterioration over time was found in crown length and BoP among the SC cases. CONCLUSION: Among the IT cases, an improvement in outcomes was noted over time. When comparing SC cases the colour of the crown and overbite had improved, while crown length and BoP had deteriorated over time.

A 10-year-old boy with class II oligodontia treated with buccal fixed appliances and agenesis space closure of the four second premolars: Case report No. 230075 - Titularisation Collège Européen Orthodontie (CEO), European College of Orthodontics.

The patient presented in this case report is a 10-year-old boy with hyperdivergent skeletal Class II associated with familial genetic agenesis of the second premolars. The treatment plan chosen was to close the spaces of agenesis using a bimaxillary appliance fixed buccally. The advantages and disadvantages of this treatment option were discussed. The result was stable and made it possible to avoid an implant-prosthetic solution, which would undoubtedly have been more restrictive over time.

The effect of micro-osteoperforations on the rate of maxillary incisors' retraction in orthodontic space closure: a randomized controlled clinical trial.

BACKGROUND: This single-centered randomized controlled clinical trial aimed to evaluate the effectiveness of micro-osteoperforations (MOPs) in accelerating the orthodontic retraction of maxillary incisors. METHODS: Forty-two patients aged 16-40 were recruited and randomly assigned into two groups, one which underwent MOPs (MOPG) in the buccal and palatal region of all maxillary incisors immediately before the start of retraction and one which did not (CG). Eligibility criteria included the orthodontic need for maxillary first premolars extraction and space closure in two phases. The primary outcome of the study consisted of measuring the rate of space closure and, consequently, the rate of incisors' retraction using digital model superimposition 14 days later and monthly thereafter for the next 4 months. The secondary outcomes included measuring anchorage loss, central incisors' inclination, and root length shortening, analyzed using cone beam computed tomography scans acquired before retraction and 4 months after retraction. Randomization was performed using QuickCalcs software. While clinical blinding was not possible, the image's examinator was blinded. RESULTS: Twenty-one patients were randomly assigned to each group. However, due to various reasons, a total of 37 patients (17 male and 20 female) were analyzed (mean age: 24.3 ± 8.1 years in the MOPG; 22.2 ± 4.2 years in the CG) during the trial. No statistically significant difference was found between the MOPG and the CG regarding the incisors' retraction measured at different time points at the incisal border (14 days, 0.4 mm vs. 0.5 mm; 1 month, 0.79 mm vs. 0.77 mm; 2 months, 1.47 mm vs. 1.41 mm; 3 months, 2.09 mm vs. 1.88 mm; 4 months, 2.62 mm vs. 2.29 mm) and at the cervical level (14 days, 0.28 mm vs. 0.30 mm; 1 month, 0.41 mm vs. 0.32 mm; 2 months, 0.89 mm vs. 0.61 mm; 3 months, 1.36 mm vs. 1.10 mm; 4 months, 1.73 mm vs. 1.39 mm). Similarly, no statistically significant differences were detected in the space closure, anchorage loss, central incisors' inclination, and radicular length between groups. No adverse effect was observed during the trial. CONCLUSIONS: MOPs did not accelerate the retraction of the maxillary incisors, nor were they associated with greater incisor inclination or root resorption. Trial registration ClinicalTrials.gov NCT03089996. Registered 24 March 2017- https://clinicaltrials.gov/ct2/show/NCT03089996 .

Spontaneous space closure in patients treated with early extraction of the first permanent molar: a retrospective cohort study using radiographs.

OBJECTIVES: To assess the success rate of spontaneous space closure after extraction of the first permanent molar (FPM) in the maxilla and the mandible, and to identify the factors that make spontaneous space closure most favorable in each. MATERIALS AND METHODS: A retrospective records-based cohort study was conducted through a search of the database of the Public Dental Service, Stockholm County Council, Stockholm, for young adults born between 2000 and 2001, who underwent extraction of one or more FPM between 2006 and 2016. A total of 995 extracted teeth were identified, of which 203 teeth in 155 patients met the inclusion criteria. RESULTS: Of the 203 extracted teeth, 166 (81.8%) did not receive any orthodontic treatment. The success rate for space closure in orthodontically treated patients was 91.9%. The success rate for spontaneous space closure was 84.3%. All unsuccessful spontaneous space closure in the maxilla occurred in patients older than 12 years. The dental developmental stage of the second permanent molar (SPM) had a statistically significant association with spontaneous space closure in the mandible (P < .001). CONCLUSIONS: The success rate of spontaneous space closure was high (84.3%) and was higher in the maxilla (94.1%) than the mandible (74.1%). Age at time of extraction and dental developmental stage of the SPM were significant factors for successful spontaneous space closure in the maxilla and mandible, respectively.

Non-compliance treatment in a young adult full-step class II division 2 malocclusion with preadjusted lingual appliance and upper first molars extractions.

This case report describes a complex full-step class II case in a young adult patient treated with lingual straight-wire appliance and upper first molar extraction. As the patient refused a surgical treatment, she was offered the best possible camouflage with the double aim of obtaining an ideal occlusal relationship and maintaining the profile; appropriate biomechanical strategies, including extraction choice and anchorage control during space closure, were needed to achieve the planned results. This case report demonstrates the possibility of successfully resolving severe sagittal discrepancies in an adult patient without surgical treatment by means of a completely invisible non-compliance technique, with the extraction of the most compromised teeth. This report also underlines the need for careful planning during both diagnostic and treatment phases, in order to obtain the best results.

O uso da versatilidade do bráquete MBT no tratamento da agenesia de incisivo lateral superior ­ relato de caso / Usage of MBT versatility for maxillary lateral incisor agenesis ­ a case report

A agenesia dos incisivos laterais superiores compromete a função e a estética, prejudicando o desenvolvimento e autoestima do paciente. O tratamento pode se dar pela abertura dos espaços e reposição dos dentes ausentes por meio de implantes ou reposição mesial dos caninos, seguido pelo seu recontorno em incisivos laterais. A transformação dos caninos em laterais apresenta diversos desafios ao ortodontista devido às diferenças entre torque, volume e cor entre esses dentes, o que, se não devidamente corrigido, pode impactar negativamente no resultado do tratamento. A técnica MBT apresenta diversas versatilidades de bráquetes que podem ser utilizadas com a finalidade de otimizar a movimentação, compensar as diferenças anatômicas e facilitar o tratamento de diversos tipos de casos com arco reto. O caso clínico apresentado mostra o tratamento da agenesia dos incisivos laterais superiores por meio do fechamento de espaço em uma paciente padrão III, com mordida cruzada anterior seguindo a técnica MBT, fazendo uso das relatadas versatilidades de bráquetes de caninos e pré-molares para atingir um posicionamento ideal desses dentes, com as alterações de torque e angulações necessárias. O tratamento incluiu o fechamento de espaços, a extração de pré- -molares inferiores e transformação dos caninos em incisivos laterais, obtendo uma correta relação anterior, oclusão funcional e bom resultado estético.(AU)

Maxillary lateral incisors agenesis compromises the patient's function and aesthetics, impairing the development and self-esteem. Main treatment options are open space for future implant restoration or canine substitution. Canine substitution usually requires restorative treatment to ideally recreate maxillary lateral incisors torque, volume, and color to achieve treatment goals and satisfy the patient's expectations. MBT system presents versatilities that can be used to optimize orthodontic movements, compensate dental anatomic discrepancies, and facilitate some straight-wire cases. This case report describes the orthodontic management of a Class III with anterior cross-bite patient that presented maxillary lateral incisor agenesis. The patient was treated with canine substitution following the MBT technique. Versatilities for canine and premolars were used to achieve the best position, torque, and angulation. The treatment also included mandibular first premolar extraction, space closing, and restorative treatment to re-anatomize the canine into a lateral incisor, achieving proper anterior relation, functional occlusion, and best esthetic result (AU)

Effect of premolar extraction and anchorage type for orthodontic space closure on upper airway dimensions and position of hyoid bone in adults: a retrospective cephalometric assessment.

Background: This study aimed to assess the effect of premolar extraction and anchorage type for orthodontic space closure on upper airway dimensions and position of hyoid bone in adults by cephalometric assessment. Methods: This retrospective study was conducted on 142 cephalograms of patients who underwent orthodontic treatment with premolar extraction in four groups of (I) 40 class I patients with bimaxillary protrusion and maximum anchorage, (II) 40 class I patients with moderate crowding and anchorage, (III) 40 class II patients with maximum anchorage, and (IV) 22 skeletal class III patients with maximum anchorage. The dimensions of the nasopharynx, velopharynx, oropharynx, and hypopharynx, and hyoid bone position were assessed on pre- and postoperative lateral cephalograms using AudaxCeph v6.1.4.3951 software. Data were analyzed by the Chi-square test, paired t-test, and Pearson's correlation test (alpha = 0.05). Results: A significant reduction in oropharyngeal, velopharyngeal, and hypopharyngeal airway dimensions was noted in groups I, III, and IV (P < 0.001), which was correlated with the magnitude of retraction of upper and lower incisors (r = 0.6 - 0.8). In group II, a significant increase was observed in oropharyngeal and velopharyngeal dimensions (P < 0.001). A significant increase in nasopharyngeal dimensions occurred in all groups (P < 0.001). Also, in groups I and III, the position of hyoid bone changed downwards and backwards, which was correlated with reduction in airway dimensions (r = 0.4 - 0.6). Conclusion: According to the present results, extraction orthodontic treatment affects upper airway dimensions and hyoid bone position. Maximum anchorage decreases airway dimensions while moderate anchorage increases airway dimensions.

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

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

The effect of early versus delayed space closure on the rate of orthodontic tooth movement: a systematic review and meta-analysis.

BACKGROUND: Orthodontic space closure of extraction sites can be initiated early, within 1-week post-extraction, or it can be delayed for a month or more. OBJECTIVE: This systematic review aimed to evaluate the effect of early versus delayed initiation of space closure after tooth extraction on the rate of orthodontic tooth movement. SEARCH METHODS: Unrestricted search of 10 electronic databases was conducted until September 2022. SELECTION CRITERIA: Randomized controlled trials (RCTs) investigating the initiation time of space closure of extraction sites in patients undergoing orthodontic treatment were included. DATA COLLECTION AND ANALYSIS: Data items were extracted using a pre-piloted extraction form. The Cochrane's risk of bias tool (ROB 2.0) and the Grading of Recommendations, Assessment, Development, and Evaluation approach were used for quality assessment. Meta-analysis was undertaken if there are at least two trials reporting the same outcome. RESULTS: Eleven RCTs met the inclusion criteria. Meta-analysis revealed that early canine retraction resulted in a statistically significant higher rate of maxillary canine retraction when compared to delayed canine retraction [mean difference (MD); 0.17 mm/month, 95% CI: 0.06 to 0.28, P = 0.003, 4 RCTs, moderate quality]. Duration of space closure was shorter in the early space closure group, but not statistically significant (MD; 1.11 months, 95% CI: -0.27 to 2.49, P = 0.11, 2 RCTs, low quality). The incidence of gingival invaginations was not statistically different between early and delayed space closure groups (Odds ratio; 0.79, 95% CI: 0.27 to 2.29, 2 RCTs, P = 0.66, very low quality). Qualitative synthesis found no statistically significant differences between the two groups regarding anchorage loss, root resorption, tooth tipping, and alveolar bone height. CONCLUSIONS: Based on the available evidence, early traction within the first week after tooth extraction has a minimal clinically significant effect on the rate of tooth movement compared to delayed traction. Further high-quality RCTs with standardized time points and measurement methods are still needed. REGISTRATION: PROSPERO (CRD42022346026).

A cost analysis of orthodontic space closure and implant treatment in patients missing maxillary lateral incisors with a long-term perspective.

OBJECTIVE: Few studies within orthodontics present both economic and clinical findings. Missing maxillary lateral incisors is a frequently occurring anomaly. The treatment alternatives most used are orthodontic space closure and prosthetic replacement of the missing tooth. Our aim is to compare the total societal costs of orthodontic space closure (SC) and implant therapy (IT) in patients missing maxillary lateral incisors. METHODS: Records of 32 patients treated with SC (n = 18) or IT (n = 14) due to missing maxillary lateral incisors were retrieved from the archives. Direct costs and indirect costs in the short- and long-term were analysed using a cost analysis with a societal perspective up of to 12 years post-treatment. RESULTS: Comparing cases treated with SC and IT, the difference in direct short-term costs for treatment is €735.54, whereas SC is the least costly. There is no difference between SC and IT in short-term parent loss of productivity, long-term loss of productivity, costs for transportation, or direct long-term costs. A difference was found between SC and IT-in favour of SC-when comparing patients' loss of productivity (P = 0.007), short-term societal costs (P < 0.001), long-term societal costs (P = 0.037), and total societal costs (P < 0.001). LIMITATIONS: There is a limited number of patient records. Local factors such as subsidies, urban versus rural areas, taxes, etc. can influence monetary variables, so the transferability to other settings may be limited. CONCLUSION: Patients treated with SC have a lower total societal cost compared to patients treated with IT. There was a difference in productivity loss for patients between SC and IT; however, concerning other indirect parameters and direct long-term costs, there was no difference between the two treatments.

Post-trauma complex orthodontic approach: the impact of psychological issues of bullying on treatment decision.

OBJECTIVE: This article aims to discuss the multidisciplinary approach required in the treatment of cases of impaction and ankylosis of permanent teeth, associated with a history of trauma, considering the psychological state of the child and family when faced with a traumatic case of bullying, by reporting the complex treatment of a central incisor needing to be orthodontically moved across the midline. CONCLUSION: This clinical case was a major challenge, which included complex multidisciplinary procedures. Results and stability after 26 months of retention indicated successful orthodontic space closure of two maxillary teeth, without the use of implants or prostheses, in an adolescent patient who had a history of dental trauma, alveolar bone loss, and an uncertain initial prognosis.

The impact of the loss of first permanent molars on the duration of treatment in patients treated with orthodontic space closure and without skeletal anchorage.

BACKGROUND: This study aims to evaluate the impact of the loss of permanent molars on the duration of orthodontic treatment for space closure and without skeletal anchorage. METHODS: Records at the beginning (T0) and the end (T1) of orthodontic treatment were selected retrospectively. Patients were divided into two groups: loss of molar (n = 19) and control, without loss (n = 24). The impact of loss on treatment time was assessed using multiple linear regression adjusted for the number of absences, bonding failures, age, sex, PAR index at T0 and T1 at p<0.05. Treatment time was also evaluated by the number of losses and which arches were involved (upper, lower). The systematic and random errors for the PAR index were verified using the intraclass correlation coefficient (ICC) and the Dahlberg formula, respectively. RESULTS: A small random error (1.51) and excellent replicability (ICC = 99.6) were observed. Overall average treatment time was 22.5 months (± 7.95) for the group without loss and 44.7 months (± 17.3) with a loss. Treatment time was longer in cases where there was a higher number of missing molars and when both arches were involved. In addition to the loss (ß = 4.25, p < 0.001), the number of missed appointments (ß = 2.88, p < 0.001) had a significant effect and increased treatment time. Bonding failures, gender, age, and PAR index at T0 and T1 were not significantly associated with treatment time in the multivariate model (p > 0.05). CONCLUSION: Loss of the first permanent molar has a negative impact on orthodontic treatment time in cases of space closure. The treatment time is longer when there are more tooth losses and arches involved. Treatment time also increases with greater numbers of missed clinical appointments.

A comparative assessment of the amount and rate of orthodontic space closure toward a healed vs recent lower premolar extraction site.

OBJECTIVES: To investigate and compare the amount and rate of space closure and tooth tipping during orthodontic space closure toward a recent vs healed first premolar extraction site. MATERIALS AND METHODS: The mandibular arches of 23 patients were included. Treatment plans included lower first premolar extractions. After reaching 0.019 × 0.025-inch stainless-steel archwires (SSAW), patients were subdivided into two groups (Group 1: space closure was carried out toward a healed first premolar extraction space and Group 2: space closure was carried out immediately after first premolar extraction). Elastomeric power chain from second molar to second molar was used to close lower extraction spaces. The following time points were defined: T1: just before space closure; T2-T4: 1-3 months after initial space closure. Records consisted of dental study models. The amount and rate of extraction space closure were evaluated at each time point. RESULTS: In Group 1 (healed socket), a total amount of 1.98 mm (coronally) and 1.75 mm (gingivally) of space closure was achieved. The rate of space closure was 0.66 mm/month coronally and 0.58 mm/month gingivally. In Group 2 (recent socket), the total amount of space closure was 3.02 mm coronally and 2.68 mm gingivally. The rate of space closure was 1.01 mm/month coronally and 0.89 mm/month gingivally. Differences between the two groups were significant (P < .01). Tipping of adjacent teeth during space closure was similar in both groups (P > .05). CONCLUSIONS: In the lower arch, the amount and rate of space closure toward a recent extraction site were higher than that toward a healed extraction socket with similar tipping of teeth in both groups.

Comparing patient-centered outcomes and efficiency of space closure between nickel-titanium closed-coil springs and elastomeric power chains during orthodontic treatment.

OBJECTIVES: To compare patient-reported pain, discomfort, and difficulty in maintaining proper brushing between nickel-titanium closed-coil springs (CS) and elastomeric power chains (PC) when used for space closure. The secondary aims were to compare plaque control and efficiency of space closure between these two force delivery systems. MATERIALS AND METHODS: A total of 48 patients who required extractions of upper first premolars and distal movement of upper canines had the CS randomly allocated to either the right or left side. Blinding was applied at data collection and analysis. Primary outcomes were pain intensity measured on visual analog scale, pain onset and duration, discomfort, and difficulty in maintaining proper brushing from the start of canine retraction at baseline and at 6 and 12 weeks thereafter. Secondary outcomes were plaque scores and the rate of space closure. RESULTS: No significant differences in mean pain scores, pain onset, and duration at different time intervals between CS and PC were observed. The CS side was significantly less comfortable than the PC (P < .0001) and more difficult to keep clean (P = .008). No significant differences in plaque scores were observed between CS and PC groups at any time interval. CS produced a faster rate of space closure than did PC (P = .008). CONCLUSIONS: CS were less tolerated than PC by patients but produced an average of 0.5 mm more movement than did the PC during the 12-week study period.

The effect of micro-osteoperforations on orthodontic space closure investigated over 12 weeks: a split-mouth, randomized controlled clinical trial.

OBJECTIVES: To evaluate the effects of minimally invasive micro-osteoperforations (MOPs) on orthodontic tooth movement and pain. DESIGN: Prospective, split-mouth, randomized controlled trial. SETTING: Single-centre, university hospital. METHODS: Twenty subjects requiring maxillary first premolar extractions were included. Right and left sides of the maxilla were randomly allocated into experimental and controls. Space closure was initiated following alignment on 0.20″ stainless steel archwires, using 150 g force, applied by coil springs on power arms. Nance-TPA was used for anchorage. On the experimental side, two 5 mm deep MOPs in vertical alignment on distal aspect of the maxillary canine mid-root region were performed prior to space closure. OUTCOMES: The primary outcome was the amount of tooth movement during space closure, measured every 4 weeks for 12 weeks (T1, T2, and T3). Secondary outcome was the pain levels related to MOP, measured using Visual Analogue Scale (VAS) questionnaires. Significance was set at P < 0.01. RANDOMIZATION: Randomization was generated using a randomization table, and allocation was concealed in sequentially numbered, opaque, sealed envelopes. BLINDING: Blinding was not possible during the experiment but assessor was blinded during outcome assessment. RESULTS: All subjects completed the study, with tooth movement measurements available for all 20 patients for T0-T2. In three patients, space was closed on one side at T2. The average tooth movement between sides at three intervals (T0-T1, T1-T2, and T2-T3) were not significantly different. Overall difference following 12 weeks (T0-T3) was 0.69 mm higher on the experimental side (P < 0.001). No harms were observed. LIMITATIONS: Short-term study, cast measurements done with digital callipers. CONCLUSION: This 12-week randomized split-mouth controlled clinical trial showed two MOPs that are 5 mm deep, applied once prior to space closure, did not create clinically significant increase in maxillary premolar space closure. PROTOCOL: The protocol was not published before trial commencement. REGISTRATION: Trial was not registered. FUNDING: The Australian Society of Orthodontists Foundation for Research and Education.

Orthodontic space closure in sliding mechanics: a systematic review and meta-analysis.

BACKGROUND/OBJECTIVES: The aim of this systematic review was to compare the different force delivery systems for orthodontic space closure by sliding mechanics. SEARCH METHODS: Multiple sources including Cochrane Central, Ovid Medline, Embase etc. were used to identify all relevant studies. SELECTION CRITERIA: Randomized controlled trials (RCT) of parallel-group and split-mouth designs were included. PARTICIPANTS: Orthodontic patients of any age treated with fixed orthodontic appliances and requiring space closure. DATA COLLECTION AND ANALYSIS: Search result screening, data extraction and quality assessment were performed independently and in duplicate by 2 reviewers. The included studies were grouped into parallel-arm and split-mouth studies and subgroup analysis was then performed for the type of retraction subsets; en-masse and individual canine retraction. A traditional meta-analysis, and network meta-analysis (NMA) for direct and indirect comparisons for the rate of space closure were performed. RESULTS: Thirteen studies, six parallel-arm and seven split-mouth were included. The traditional meta-analysis comparing Nickel-titanium (NiTi) closed coil springs and elastomeric power chain for the rate of tooth movement showed statistically significant difference favouring NiTi springs (MD: 0.24; 95% CI, 0.03-0.45; I2 0%, P = 0.02) and the comparison between NiTi springs and active ligatures also showed statistically significant result favouring NiTi springs (MD: 0.53; 95% CI, 0.44-0.63; I2 0%, P ˂ 0.00001) for the rate of tooth movement. NMA for the rate of space closure showed fairly confident evidence for NiTi coil springs when compared with elastomeric chain and active ligatures. The NiTi coil spring ranked best between all methods of space closure. CONCLUSIONS: There is moderate quality evidence in favour of NiTi coil springs for the rate of space closure when compared with active ligature and low quality of evidence favouring NiTi springs when compared with elastomeric chain. The ranking from NMA showed NiTi coil springs to be the best method for space closure with 99% chance. An urgent need for standardization of study designs and the need for development of an agreed core outcome sets and core outcome instrument measurement sets is evident. REGISTRATION: PROSPERO CRD42020157811.