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Space closure is a challenging and time-consuming phase of orthodontic treatment with fixed appliances. This systematic review evaluated canine retraction duration using fixed appliances after maxillary first premolar extraction.Unrestricted systematic literature searches were conducted in 8 databases for randomized clinical trials, assessing the duration and rate of maxillary canine retraction using fixed appliances with or without treatment adjuncts published up to July 2021. Study selection, data extraction, and risk of bias evaluation were conducted independently and in duplicate. Random-effects meta-analyses of average rates or mean differences (MD) and 95% confidence intervals (CI) were conducted at α = 5%, followed by sensitivity and Grading of Recommendations Assessment, Development, and Evaluation analysis.Fifty randomized clinical trials (6 parallel and 44 split-mouth designs) covering 811 participants (mean age 19.9 years; 34% male) were included. The estimated average pooled duration to achieve complete canine retraction was 4.98 months (2 trials; 95% CI, -2.9 to 12.88 months). Pooled average canine retraction was 0.97 mm at months 0-1 (23 trials; 95% CI, 0.79-1.16), 1.83 mm at months 0-2 (20 trials; 95% CI, 1.52-2.14), 2.44 mm at months 0-3 (23 trials; 95% CI, 2.10-2.79), 3.49 mm at months 0-4 (6 trials; 95% CI, 1.81-5.17) and 4.25 mm at months 0-5 (2 trials; 95% CI, 0.36-8.14). Surgically-assisted orthodontics was associated with greater canine retraction at all time points: months 0-1 (10 trials; MD, 0.52 mm; P = 0.004), months 0-2 (8 trials; MD, 0.53 mm; P = 0.04), months 0-3 (8 trials; MD, 0.67 mm; P = 0.01), and months 0-4 (3 trials; MD, 1.13 mm; P = 0.01), whereas subgroup analyses indicated significant effects of anchorage reinforcement method and bracket slot size on canine retraction.The average time to achieve complete retraction of the maxillary canine using fixed appliances was around 5.0 months. Most studies used split-mouth randomization to investigate canine retraction for around 1-3 months, with substantial heterogeneity across studies. At 3 months of treatment, high-quality evidence supported greater canine retraction with surgically-assisted orthodontics.

A key goal of orthodontic treatment with fixed appliances is alignment of the dentition, and this remains a commonly selected outcome in clinical studies investigating orthodontic tooth movement. This systematic review has evaluated treatment duration to achieve alignment of the mandibular dentition using fixed appliances.Systematic literature searches without restrictions were undertaken in 9 databases for randomized clinical trials (RCTs) assessing duration and rate of tooth alignment using fixed appliances with or without treatment adjuncts published up to January 2021. After duplicate study selection, data extraction, and risk of bias assessment according to Cochrane, random-effects meta-analyses of aggregate data, and individual patient data were conducted.Thirty-five trials were included with 2258 participants (39% male; mean age 17.8 years), giving a pooled duration to achieve whole-arch alignment of the mandibular dentition of 263.0 days (4 trials; 95% confidence interval [CI], 186.7-339.4 days) and incisor alignment in the mandibular arch of 100.7 days (9 trials; 95% CI, 84.1-117.4 days). Surgical-assisted orthodontics was associated with reduced duration of incisor alignment: mean difference of 44.3 days less (4 trials; 95% CI, 20.0-68.9 days; P 0.001; high quality of evidence), whereas subgroup and meta-regression analyses indicated significant effects of baseline crowding and premolar extractions. Individual patient data analysis from 3 RCTs indicated that for each additional participant age year, whole-arch alignment of the mandibular dentition took 13.7 days longer (3 trials; 95% CI, 7.7-17.7 days; P 0.001) and for each additional mm of irregularity, 17.5 days more were needed (2 trials; 95% CI, 9.8-25.2 days; P 0.001).Patient and treatment-related characteristics can significantly affect the duration of tooth alignment and should be taken into account both clinically and when designing trial outcomes. Future research studies investigating rates of orthodontic tooth alignment would benefit from adequate sample sizes and a more consistent methodology in outcome assessment. Data in this systematic review provides a basis for appropriate trial design for future RCTs investigating the rate of orthodontic tooth alignment with fixed appliances.

Objectives Three-dimensional (3D) printing technology is an emerging manufacturing process for many orthodontic appliances, and the aim of this study was to evaluate the mechanical properties of resin-based materials as alternatives for the in-house preparation of orthodontic brackets. Material and Methods Two types of 3D printed resins used for temporary (T) and permanent (P) crown fabrication were included in this study. Ten blocks from each resin were manufactured by a 3D printer and, after embedding them in acrylic resin, the samples were subjected to metallographic grinding and polishing, followed by instrumented indentation testing (IIT). Martens hardness (HM), indentation modulus (EIT), and elastic index (ηIT) were determined with a Vickers indenter recording force-indentation depth curves from each specimen. After calculating descriptive statistics, differences between material types were investigated with Wilcoxon rank sum test accounting for clustering of measurements within specimens at alpha = 5%. Results No statistically significant differences in the mechanical properties of the two tested materials were seen: HM: median 279 N/mm2 (interquartile range [IQR] 275–287 N/mm2) for T and median 279 N/mm2 (IQR 270–285 N/mm2) for P (P value = 0.63); EIT: median 5548 MPa (IQR 5425–5834 MPa) for T and median 5644 (IQR 5420–5850 MPa) for P (P value = 0.84); ηIT: median 47.1% (46.0–47.7%) for T and median 46.0% (IQR 45.4–47.8%) for P (P value = 0.24). Conclusions Under the limitations of this study, it may be concluded that the mechanical properties of the two 3D printed resins tested are equal, and thus, no differences in their clinical performance are expected.

Background Even though treatment of Class II malocclusion with premolar extractions and incisor retraction might affect incisor inclination and soft tissue profile, the effects of bracket prescription on this have not been thoroughly assessed. Methods Fifty patients (mean age: 13.6 years; 34% male) receiving extraction-based treatment with either standard Edgewise or pre-adjusted appliances were included. Between-group differences in the incisor inclination assessed with lateral cephalograms were analyzed statistically with linear/logistic regression at 5%. Results Treatment-induced changes included retroclination of the upper/lower incisors (−3.0° and −2.0°, respectively), retraction of the upper/lower incisors (−3.4 mm and −1.5 mm, respectively), retraction of the upper/lower lip (−2.1 mm and −2.0 mm, respectively), and enlargement of the nasolabial angle (+1.6°). Analysis of the data adjusting for confounders indicated that the pre-adjusted group, after treatment, had larger inclination of the upper or lower incisors (+3.2° and +4.5°, respectively), more prominent upper incisors relative to the facial plane (+1.3 mm), and smaller interincisal angle (−7.3 or −7.7°). Post-treatment upper incisor inclination fell within the cephalometric norm significantly more in the pre-adjusted than in the standard Edgewise group (odds ratio 4.3; 95% confidence interval 1.1–16.6). No differences were found in lower incisor prominence, upper/lower lip prominence, or nasolabial angle. Conclusions Pre-adjusted appliances were associated with increased inclination of the upper and lower incisors, with more prominent upper incisors, and with more acute interincisal angle after retraction compared with standard Edgewise appliances. However, such differences did not translate in greater retraction of the upper/lower lips and greater nasolabial angle.

Adequate control of the vertical dimension is of great importance in orthodontic treatment. Although existing evidence is very limited, extraction of four premolars is thought to contribute towards improved control of anterior facial height compared with non-extraction treatment protocols. Thus, the aim of this retrospective cohort study was to compare the effect of fixed-appliance treatment with extraction of four premolars to non-extraction treatment on the skeletal vertical dimension.A consecutive sample of 76 children with skeletal hyperdivergence (49% male; mean age 11.9 years) was divided into two groups for treatment with either non-extraction (n = 31) or extraction of four premolars (n = 45). Baseline characteristics were comparable: overjet 5.1 ± 2.5 mm, overbite 2.4 ± 1.9 mm, ANB angle 4.6 ± 2.3°, and SN-ML angle 40.2 ± 3.5°. Patients were treated with standard edgewise fixed appliances with closing loops/sliding mechanics. Vertical skeletal and dental outcomes were measured on lateral cephalograms before and after treatment. Data were analyzed with linear regression at 5%.Compared to non-extraction treatment, treatment with premolar extractions had no significant effect on the SN-ML angle (difference (Δ) = 0.07°; 95% confidence interval -0.90 to 1.01°; P = 0.88). Statistically significant changes between the extraction and non-extraction groups were only found for the parameters SNA (Δ -1.47°; P = 0.003), ANB (Δ -1.17°; P = 0.004), SN-OP (Δ -1.48°; P = 0.04), and L1-ML (Δ -6.39°; P 0.001).Orthodontic treatment of children with skeletal hyperdivergence using systematic extraction of four premolars had minimal effects on the vertical facial dimension compared to non-extraction treatment.ZIELSETZUNG: Eine adäquate Kontrolle der vertikalen Dimension ist in der kieferorthopädischen Behandlung von großer Bedeutung. Auch wenn die Evidenzlage sehr begrenzt ist, geht man davon aus, dass die Extraktion von 4 Prämolaren im Vergleich zu nichtextraktiven Behandlungsprotokollen zu einer besseren Kontrolle der anterioren Gesichtshöhe beiträgt. Ziel dieser retrospektiven Kohortenstudie war es daher, die Auswirkung einer festsitzenden Behandlung mit Extraktion von 4 Prämolaren mit einer nichtextraktiven Behandlung auf die vertikale Dimension des Skeletts zu vergleichen.Eine konsekutive Stichprobe von 76 Kindern mit skelettaler Hyperdivergenz (49% männlich; Durchschnittsalter 11,9 Jahre) wurde in 2 Gruppen aufgeteilt, die entweder mit einer Nichtextraktionsbehandlung (n = 31) oder einer Extraktion von 4 Prämolaren (n = 45) behandelt wurden. Die Ausgangsdaten waren vergleichbar: Sagittale Frontzahnstufe 5,1 ± 2,5 mm, vertikale Frontzahnstufe 2,4 ± 1,9 mm, ANB-Winkel 4,6 ± 2,3° und SN-ML-Winkel 40,2 ± 3,5°. Die Patienten wurden mit festsitzenden Standardapparaturen mit „closing loops“ /Gleitmechanik behandelt. Die vertikalen skelettalen und die dentalen Resultate wurden auf lateralen Kephalogrammen vor und nach der Behandlung ermittelt. Die Ergebnisse wurden mit einer linearen Regression von 5% ausgewertet.Im Vergleich zu einer Behandlung ohne Extraktion hatte die Behandlung mit Prämolarenextraktionen keine signifikante Auswirkung auf den SN-ML-Winkel (Differenz [Δ] = 0,07°; 95%-Konfidenzintervall [KI] -0,90 bis 1,01°; p 0,88). Statistisch signifikante Veränderungen zwischen der Extraktions- und der Nichtextraktionsgruppe wurden nur für die Parameter SNA (Δ −1,47°; p = 0,003), ANB (Δ −1,17°; p = 0,004), SN-OP (Δ −1,48°; p = 0,04) und L1-ML (Δ −6,39°; p 0,001) festgestellt.Die kieferorthopädische Behandlung von Kindern mit skelettaler Hyperdivergenz durch systematische Extraktion von 4 Prämolaren hatte minimale Auswirkungen auf die vertikale Gesichtsdimension im Vergleich zu einer Behandlung ohne Extraktion.

Purpose: To investigate marginal integrity of restorations applied with preheated and non- preheated composite, flowable composite, sonically activated composite, and a new thermo-viscous bulk-fill composite using near-infrared technology for preheating, in class V cavities of human molars. Materials and Methods: Standardized cavities were prepared on the buccal surfaces of 60 human mandibular molars and restored with one of the following resin composite materials after application of an etch-and-rinse adhesive (OptiBond FL, Kerr): non-preheated or preheated conventional composite (Filtek Supreme XTE, 3M Oral Care), preheated thermo-viscous composite (VisCalor bulk, V oco), soncially activated composite (SonicFill 3, Kerr), or flowable composite (Filtek Supreme XTE Flowable, 3M Oral Care) applied in bulk or as a lining material using the snow-plow technique. After light curing and polishing, the percentage of continuous margins (PCM) of the restorations in enamel and dentin was assessed using SEM both before and after thermomechanical loading (TML). TML was carried out with 3000 thermal cycles (5°C–50°C) and a simultaneous mechanical stress application with 1.2 million load-cycles (1.7 Hz, 49 N) in a computer-controlled masticator. Non-parametric statistical analysis was performed using Wilcoxon, Kruskal-Wallis, and Mann-Whitney U-tests (α = 0.05). Results: All groups revealed a significant decline in marginal integrity after TML in both enamel and dentin. Although the flowable group in enamel and the snow-plow group in dentin showed the highest PCM before TML, the differences between the groups were compensated after TML. Conclusion: All of the tested composites and application methods showed similar marginal integrities after thermomechanical loading and can be recommended for clinical implementation.

Summary Aim To assess the prevalence of and identify factors associated with SPIN in abstracts of orthodontic meta-analyses. Materials and methods Electronic search was performed within the contents of five orthodontic journals and the Cochrane Database of Systematic Reviews (CDSR) to identify meta-analyses of studies involving humans, from 1 January 2000 until 31 August 2020. Inclusion of SPIN in the abstract of meta-analyses, defined as misleading reporting, misleading interpretation, and inappropriate extrapolation of the findings, was documented. Extent of SPIN and associations with journal and year of publication, type of study, number of authors, continent of authorship, methodologist involvement, funding, and significance of the primary outcome were investigated. Results One hundred and nine meta-analyses were identified, with the highest proportion being published in the European Journal of Orthodontics (EJO: 31/109; 28.4%). Inclusion of SPIN, in at least one domain, was recorded in nearly half (53/109; 48.6%) of the studies, of which 30 (56.6%) included 2 or more domains of SPIN. Meta-analyses of observational studies presented 1.66 times higher risk for including SPIN in their abstracts compared with interventional ones [95% confidence intervals (CIs): 1.14, 2.40; P = 0.007], after adjusting for a number of predictors. Studies with a large number of authors (≥6) presented 1.76 times higher risk of SPIN (≥6 versus 1–3: 95% CIs: 1.04, 2.97; Wald test, P = 0.021), conditional on the pre-defined predictors. Conclusions Flaws in the reporting and interpretation of the findings of abstracts of meta-analyses, as framed by inclusion of SPIN are persistent in orthodontic research, being more prevalent in meta-analyses of observational studies. Consistent, multidirectional efforts should be endorsed to improve the quality of the disseminated research findings.

Purpose Orthodontic fixed appliances have been proven to be effective in treating a wide variety of malocclusions, and different types of appliances have emerged during recent decades. However, the comparative effects of different appliances have not been adequately assessed. Thus, the aim was to assess the occlusal outcome of orthodontic treatment with preadjusted straight-wire (SWIRE) and standard edgewise (SEDGE) appliances. Methods In all, 56 patients (mean age: 13.5 years; 45% male) receiving extraction-based treatment with either SWIRE or SEDGE appliances were included. Between-group differences in the occlusal outcome assessed with the American Board of Orthodontists Objective Grading System (ABO-OGS) and treatment duration were analyzed statistically at the 5% level. Results The average ABO-OGS score was 31.3 ± 7.2 points and 34.0 ± 10.4 points in the SWIRE and SEDGE groups with no statistically significant difference between groups (P = 0.26). Treatment duration was significantly shorter in the SWIRE group compared to the SEDGE group, with an average difference of −6.8 months (95% confidence interval [95% CI] = −9.6 to −4.0 months; P P Conclusion Similar treatment outcomes were observed after premolar extraction treatment with SWIRE and SEDGE appliances. On the other hand, SEDGE appliances were associated with prolonged treatment duration and more visits needed to complete treatment compared to SWIRE appliances.

OBJECTIVE The aim of this study was to compare the mechanical properties of orthodontic aligners among different commercially available 3D printing devices. MATERIALS AND METHODS Five 3D printers (Ka:rv LP 550, Swinwon; "KAR"), (L120, Dazz 3D; "L12"), (MiiCraft 125, Miicraft Jena; "MIC"), (Slash 2, Uniz; "SLS") and (Pro 95, SprintRay; "PRO") were used to prepare orthodontic aligners with dental resin (Tera Harz TC-85DAW, Graphy). The central incisors of each aligner were cut, prepared and evaluated in terms of Martens-Hardness (HM), indentation-modulus (EIT ) and elastic-index (ηIT ) as per ISO14577-1:2002. Force-indentation curves were recorded and differences among printers were checked with generalized linear regressions (alpha=5%). RESULTS Statistically significant differences were seen for all mechanical properties (P

Orthodontic aligners printed with in-office 3-dimensional (3D) procedures have been described, but no data on their biocompatibility exist. This study investigates the cytotoxicity and estrogenicity of a 3D-printed orthodontic aligner by assessing its biological and behavioral effects.Ten sets of 1 type of aligner were immersed in sterile deionized water for 14 days, and the cytotoxicity and estrogenicity of released factors were assessed via MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assays on human gingival fibroblasts and the estrogen-sensitive MCF-7 and the estrogen-insensitive MDA-MB-231 breast cancer cell lines. 17β-Estradiol and bisphenol-A were used as positive controls. The statistical analysis of data was performed with generalized linear models at a 0.05 level of significance.No signs of cytotoxicity were seen for the aligner samples for concentrations (v/v) of 20% (P = 0.32), 10% (P = 0.79), or 5% (P = 0.76). The antioxidant activity expressed as the capacity to reduce intracellular levels of reactive oxygen species was not affected in the aligner samples (P = 0.08). No significant estrogenicity was induced by the aligner samples compared with eluents from the negative control for both MCF-7 (P = 0.65) and MDA-MB-231 (P = 0.78). As expected, 17β-Estradiol and bisphenol-A stimulated MCF-7 cell proliferation, whereas no effect was observed on MDA-MB-231 cells.In conclusion, if any factors were released during the 14-day aging of 3D-printed aligners in water, these were not found to be cytotoxic for human gingival fibroblasts and did not affect their intracellular reactive oxygen species levels. Moreover, no estrogenic effects of these putative eluates were observed based on an E-screen assay.

BackgroundScoping Reviews (ScRs) have emerged in the orthodontic literature as a new methodological perspective to collate and summarize scientific evidence. The aim of the present study was to identify and record the proportion of Scoping Reviews in orthodontics that have been clearly and adequately justified, based on the methodological framework of such types of reviews. Associations with a number of publication characteristics were also sought. Three major databases, namely PubMed, Scopus and Web of Science Core Collection, as well as 11 specialty orthodontic journals were electronically sought from inception until August 1, 2022, for ScRs. The primary outcome pertained to whether the published reports of the ScRs included an appropriate justification and explanation for the selection of this kind of knowledge synthesis methodology. Potential association with year, journal, continent of authorship, number of authors, methodologist involvement, appropriate reporting guidelines and registration practices followed were explored.ResultsA total of 40 ScRs were eligible for inclusion, with the majority not being adequately justified (22/40; 55.0%). The majority of studies were published from 2020 onward (32/40; 80.0%). The regression model did not reveal any significant association between justification of ScRs and a number of publication characteristics (p > 0.05 at all levels).ConclusionsLess than half of the included ScRs were adequately justified in terms of selection of the appropriate synthesis methodology. Awareness should be raised in the scientific community regarding the correctness of the use of this newly emerging type of study in orthodontics, to safeguard against any trace of research waste.

The purpose of this investigation of untreated monozygotic and dizygotic twins was to identify the genetic and environmental components to the facial soft tissue growth.The sample consisted of 52 untreated monozygotic twins (36 male and 16 female) and 46 untreated dizygotic twins (23 male and 23 female) from the Forsyth Moorrees Twin Study (1959-1975).Lateral cephalograms were taken at 12 and 17 years of age and traced to analyse facial convexity, nasolabial angle, upper and lower lip thickness, upper and lower lip profile and nose prominence. The genetic and environmental components of variance were analysed with structural equation modelling for multilevel mixed-effects model.At 12 years of age, strong additive genetic influence was seen for facial convexity (70%), upper lip profile (66%) and nose prominence (65%), whereas strong dominant genetic components were found for upper lip thickness (56%). Nevertheless, under unique environment influence were nasolabial angle (58%), lower lip profile (51%) and lower lip thickness (64%). At 17 years of age, only upper lip thickness (55%) and nose prominence (84%) were under strong additive genetic control, while the rest of the variables were under strong dominant genetic control. The only exception was lower lip thickness (61%), which is still influenced by the unique environment.Although monozygotic/dizygotic twins share at least part of their genome, at both times either additive, dominant or environmental components were found. Nevertheless, at 17 years of age most of the variables are either under additive or dominant genetic influence.

OBJECTIVES To identify the 10 most numerically prolific authors publishing in the field of orthodontics for each year over the last decade (2011-2020), describe the characteristics of these outputs and identify trends in the types of study being published. MATERIALS AND METHODS A Scopus literature search was conducted to identify the 10 most numerically prolific publishing authors in orthodontics for each year during this decade. Number and characteristics of all publications for each author were analysed with descriptive and inferential statistics. RESULTS Forty-nine different individual authors were identified who were collectively prolific for between 1-8 years within the assessment decade. These authors published a total of 2025 papers, with a median annual output of 18 papers per year; however, half of these authors published between 15-24 papers per year (range 5-200). Amongst authors, 2 or more collaborated on only 7% of the identified papers. The median number of authors per paper was 5 (range 1-27) with significant variation according to study design (P

Summary Background Empiric data on headgear wear are scarce. The aim was to examine a possible discrepancy between the duration of wearing and force application, and whether such a difference is influenced by force level or direction of traction. Materials and methods In this retrospective analysis, 122 consecutive patients were included. All were treated with headgear (three subgroups: high-pull headgear [n = 60], cervical-pull headgear [n = 32], and high-pull headgear in combination with an activator [n = 30]) and were monitored for three successive months using an electronic module. The device recorded chronographically the measured force magnitude and temperature, allowing to differentiate between the duration of headgear wear (recorded body temperature) and actual force application (recorded force). Results For all subgroups, the average recorded force application was lower than wear time (mean inactivity during wear: 15.9 ± 22.8 minutes/night). The direction of traction significantly influenced the extent and length of wear time without force application (P < 0.001): patients with cervical-pull headgear were more prone to inactive wear time (27.7 minutes/night) than patients with high-pull headgear (13.7 minutes/night) or with headgear–activator (7.8 minutes/night). The observed inter-individual variability of inactive wear time was considerable (0–134 minutes/night). The mean applied force was highly significantly associated with inactive wear time (correlation coefficient: −0.575; P < 0.001), and force levels below 250 g seem particularly related to episodes of inactivity. Conclusions There is a clear incongruity between the duration of headgear wear and the duration of force application. Inactive wear time is influenced by the direction of traction and force level applied. Clinicians should be aware of the likelihood of periods of inactive wear time and researchers should search for options to reduce or even eliminate these periods.

The aim of this international survey was to assess knowledge concerning the design, conduct, critical appraisal and synthesis of clinical studies among senior orthodontic postgraduate residents.Senior postgraduate residents from four universities in Europe and the United States were invited to complete a custom questionnaire. The overall correct answer score and proportion of residents correctly answering each of the 10 questions within the survey were analysed with descriptive statistics, analysis-of-variance, chi-squares test and linear regression at 5%.A total of 46 residents with mean age of 30.4 years scored an overall % correct score of 48.8%±13.8%, with the % of correct answers to each question ranging from 7 to 89%. The worst-answered questions pertained to correctly characterizing sensitivity and specificity (7%), number needed to treat (9%), credibility of trial synthesis in meta-analysis (35%) and publication bias (37%). The vast majority of postgraduate students could correctly identify entities that can be blinded in a randomized trial (89%), statistical power of a trial (74%) and proper methods for random allocation sequence (67%). No statistically significant differences were found among the four included universities, while residents having obtained another degree apart from dentistry scored better than others (+9.5%; 95% confidence interval: 0.6% to 18.5%; P=0.04).Postgraduate residents in orthodontics possessed moderate knowledge on evidence-based methodology. Efforts should be reinforced to assimilate research methodology perspectives in the postgraduate curricula of universities, in order to further augment critical training of orthodontic specialists.

Objectives: Mandibular anterior crowding can be treated by expanding the dental arch or by extracting teeth, usually premolars. The aim of this study was to assess long-term outcomes of extraction versus non-extraction therapies in terms of gingival recession. Methods: Fifty consecutive patients were selected, including 26non-extraction and 24extraction cases. All had been treated with fixed appliances because of well-defined comparable moderate crowding and Angle ClassI malocclusion. Patient age was documented before treatment, upon debonding, and during retention, thus, allowing the calculation of the duration of active treatment and retention. The records available for these three points in time included casts and cephalograms. The casts were used to quantify mandibular anterior crowding and the associated clinical crown lengths. Based on the cephalograms, a number of symphyseal variables were measured. Data analysis included descriptive statistics, correlation tests, and multiple regressions. Results: For accurate comparison of the extraction and non-extraction treatment groups, we required and verified that no significant intergroup differences were present with regard to initial crowding, duration of retention, and age at final record-taking. Both groups revealed increases in crown length, which fell short of statistical significance but were twice as large for canines than for incisors. The treatment decisions to extract premolars did result in significantly different topographic positions of the lower incisors, but they made no difference in the recession outcomes. None of the variables in our regression analysis was found to predict gingival recession. Conclusion: Findings of gingival recession in patients having undergone orthodontic treatment do not seem to be related to extraction/non-extraction treatment decisions.

Summary Aim To assess the representation of female authors in senior and leading positions in orthodontic research publications, as well as the fraction of women participating in the publication reports, for over a decade. In addition, association of women representation in orthodontic research and characteristics such as journal of publication, year, study design/topic, and others, were sought. Materials and methods Electronic search was performed within three major orthodontic journals, namely the European Journal of Orthodontics (EJO), the American Journal of Orthodontics and Dentofacial Orthopedics (AJODO), and the Angle Orthodontist (ANGLE) to identify all types of research articles published within two distinct year cohorts, the 2008–10 and the 2018–20. The outcomes of interest pertained to proportion of women in senior (last) and leading (first) position, and fraction of overall participation in the author list. Results A total of 2539 articles were eligible for inclusion, with an overall number of contributing authors being 11 608, of which 34.4% were female. For seniority in authorship, 30.1% (312/1038) of the publications within 2018–20 were attributed to female authors, while 25.8% (388/1501) was identified in 2008–10. Publication timeline, geographic region, and thematic topic of publication were determined as significant predictors. For leading (first) authorship, the respective percentages were 44.7% (464/1038) within 2018–20, and 34.7% (521/1501) in 2008–10. Dissemination timeline, geographic region and journal of publication were identified by the multivariable analysis, as revealing evidence of association with female leading publication authorship. Overall, the median proportion of female authors within the author list was 33.0%. Conclusions A gender gap related to Orthodontic research publications is persistent, with participation of women either as senior, or as leading authors, being suboptimal. Consistent efforts should be set in place, to facilitate more equal representation of women in research publishing, being supported by academia.

Background A non-invasive method has recently been introduced to remove osseo-integrated palatal implants by using the implantation ratchet which is designed to screw in or unscrew the implants. Although a proof of concept has been published, the torque involved to successfully explant have not been investigated so far. The aim of this study was to assess the removal torque required to explant osseo-integrated and orthodontically utilized palatal implants, and to identify potentially influencing variables. Materials and method Thirty-one consecutive patients (15 females, 16 males; mean age 24.1 ±7.4 years) with fully osseo-integrated and previously orthodontically loaded palatal implants (Orthosystem®: diameter 4.1mm/length 4.2mm/sandblasted with large grits (SLA) surface) were randomly assigned to either clockwise or counter-clockwise non-invasive explantation. The respective explantation tool with an electric torque control was placed on the abutment connection of the implant and secured by an occlusal screw. The primary outcome studied was maximal removal torque (MRT) needed to detach the implant from its socket which was recorded individually together with other potentially influencing secondary outcomes (gender, age, orthodontic loading time, use of local anaesthetics). Student’s t-test was used to contrast MRT difference for the gender, type of suprastructure, use of local anaesthetics, and rotational direction. Spearman correlations was used to investigate associations between MRT and patient’s age or duration loading time. Results Average MRT (148.6 ± 63.2N/cm) using ratchet as a non-invasive removal method of palatal implant was considered safe. The triangular head fractured of palatal implant at a torque level of 300.1 Ncm. Significantly higher explantation were recorded for male patients compared to female patients (182.0 ± 63.0 Ncm vs 112.8 ± 40.8 Ncm; P=0.001). On the other side, the mean removal torque for palatal removal in clockwise direction was non-significantly different (158.3 ± 58.6 Ncm) compared to counter-clockwise direction (139.4 ± 67.9 Ncm). Neither patient’s age (p=0.324) nor loading time (p=0.214) were significantly correlated with removal torque values. Conclusions Pertinent literature on this subject is practically non-existent, as orthodontics is presumably the only discipline where implant removal represents a treatment success. Mean MRT for successful palatal implant removal was 148.6±63.2Ncm, but a large spectrum was observed (minimum 31.5Ncm, maximum 272.8Ncm). This obvious heterogeneity underlines the importance to investigate possible influencing factors. The safe and simple non-invasive method for palatal implant removal necessitates moderate, but not high torque MRTs, independently of the torque direction. The necessary MRT seems clearly influenced by gender, but less so by patient’s age or loading time.

Background The aim of the current systematic review was to compare the radiologic effects of functional appliance Class II treatment compared to no treatment on the temporomandibular joint and its components. Methods Nine databases were searched up to June 2019 for randomized or prospective non-randomized clinical trials comparing Class II patients treated with functional appliances to untreated patients. After duplicate study selection, data extraction, and risk of bias assessment with the Cochrane tool and the ROBINS-I tool, random effects meta-analyses of mean differences (MDs) and their 95% confidence intervals (CIs) were performed, followed by the assessment of the quality of evidence with GRADE. Results A total of 11 papers on 8 unique trials with 377 patients (39.8% male; average age 10.3 years) were finally included. Limited evidence indicated that compared to untreated growing patients functional appliance treatment was associated with increased condylar width (2 studies; MD 1.1 mm; 95% CI 0.1 to 2.2 mm; very low evidence quality), decreased anterior joint space (2 studies; MD − 0.7 mm; 95% CI − 0.5 to − 0.9 mm; very low evidence quality), increased superior joint space (2 studies; MD 0.7 mm; 95% CI 0.5 to 1.0 mm; very low evidence quality), increased posterior joint space (2 studies; MD 1.0 mm; 95% CI 0.9 to 1.2 mm; very low evidence quality), and vertical displacement of the glenoid fossa (2 studies; MD 0.4 mm; 95% CI 0.1 to 0.7 mm; very low evidence quality). The main limitations affecting the validity of the present findings were the inclusion of non-randomized studies with methodological issues, imprecision due to limited samples of the included studies, and inconsistencies among studies. Conclusions Currently existing evidence from controlled clinical studies on humans indicates that functional appliance treatment is associated with positional and skeletal alterations of the temporomandibular joint in the short term compared to untreated controls. However, the clinical relevance of these changes remains unclear, while the quality of existing evidence is low due to methodological issues of existing studies. Review registration PROSPERO, CRD42018109271 Electronic supplementary material The online version of this article (10.1186/s40510-019-0286-9) contains supplementary material, which is available to authorized users.

Background The aim of the current systematic review was to compare the clinical effects of bone-borne or hybrid tooth-bone-borne rapid maxillary expansion (RME) with conventional tooth-borne RME in the treatment of maxillary deficiency. Methods Nine databases were searched up to September 2018 for randomized clinical trials comparing bone-borne or hybrid tooth-bone-borne RME to conventional tooth-borne RME in patients of any age or sex. After duplicate study selection, data extraction, and risk of bias assessment with the Cochrane tool, random effects meta-analyses of mean differences (MD) and their 95% confidence intervals (CIs) were performed, followed by assessment of the quality of evidence with GRADE. Results A total of 12 papers on 6 unique trials with 264 patients (42.4% male; average age 12.3 years) were finally included. Limited evidence indicated that bone-borne RME was associated with greater suture opening at the first molar post-retention (1 trial; MD 2.0 mm; 95% CI 1.4 to 2.6 mm; moderate evidence quality) compared to tooth-borne RME, while no significant differences could be found regarding tooth inclination, nasal cavity width, and root resorption (very low to low evidence quality). Hybrid tooth-bone-borne RME was associated with less buccal tipping of the first premolar (2 trials; MD − 4.0°; 95% CI − 0.9 to − 7.1°; moderate evidence quality) and lower nasal airway resistance post-retention (1 trial; MD − 0.2 Pa s/cm3; 95% CI − 0.4 to 0 Pa s/cm3; moderate evidence quality) compared to tooth-borne RME, while no significant difference could be found regarding skeletal maxillary width, molar inclination, and analgesic use (low to moderate evidence quality). The main limitations affecting the validity of the present findings were (a) imprecision due to the inclusion of few trials with limited sample sizes that precluded robust detection of existing differences and (b) methodological issues of the included trials that could lead to bias. Conclusions Limited evidence from randomized trials indicates that bone-borne or hybrid tooth-bone-borne RME might present advantages in terms of increased sutural opening, reduced tooth tipping, and lower nasal airway resistance compared to conventional tooth-borne RME. However, the limited number of existing studies and issues in their conduct or reporting preclude the drawing of definite conclusions. Review registration PROSPERO (CRD42017079107). Electronic supplementary material The online version of this article (10.1186/s40510-019-0261-5) contains supplementary material, which is available to authorized users.

ObjectivesTo determine the additive genetic and environmental contributions to the vertical growth of craniofacial structures.Materials and MethodsThe sample consisted of 64 untreated monozygotic (44 male, 20 female) and 61 untreated dizygotic twins (32 male, 29 female). Lateral cephalograms taken at 15 and 18 years of age were traced to analyze the sella-nasion–nasal line angle (SN-NL), nasal line–mandibular line angle (ML-NL), sella-nasion–mandibular line angle (SN-ML), sella-nasion–sella-gnathion angle (Y-axis), posterior face height/anterior face height (PFH/AFH), and lower anterior face height/anterior face height (LAFH/AFH). The genetic and environmental components of variance were analyzed with structural equation modeling for multilevel mixed effects.ResultsAt 15 years of age, strong dominant genetic control was seen for NL-ML (81%), LAFH/AFH (73%), and Y-axis (57%), whereas strong additive genetic components were found for PFH/AFH (78%), SN-NL (58%), and SN-ML (57%). Unique environmental factors accounted for 18–42% of observed variance, with SN-NL being affected the most (42%). At 18 years of age, only LAFH/AFH (86%) was under strong dominant genetic control, whereas the remainder were under additive genetic influence. The sole exception was SN-NL, which changed from additive to unique environmental influence.ConclusionsEither additive or dominant genetic components were found at 15 or 18 years of age for most vertical variables. Environmental factors accounted for about 10–40%, with SN-NL being mostly affected.

Background One of the most unfavorable side effects of fixed orthodontic treatment is white spot lesions (WSLs). Although the most important approach is prevention of WSLs, it is also essential to evaluate the efficacy of the remineralization agents. However, there is no concurrence in the literature with respect to the remineralization process of these agents. The objective of the present study was to evaluate the effects of different fluoride varnishes, enamel matrix protein, and self-assembling peptide derivatives with varying chemical compositions on remineralization of artificially created WSLs in vitro using quantitative light-induced fluorescence (QLF). Methods Artificial WSLs were created on bovine enamel samples using acidic buffer solution (pH 5, 10 days). Specimens were randomly allocated to six groups (n = 10/group): (1) Emdogain (Straumann, Basel, Switzerland), (2) Curodont Repair (Credentis AG, Switzerland), (3) Duraphat (Colgate-Palmolive, New York, NY), (4) Clinpro XT (3 M ESPE, Pymble, New South Wales, Australia), (5) Enamel Pro Varnish (Premier Dental Products, PA, USA), and (6) control (untreated). The agents were applied to the WSLs according to the manufacturers’ instructions. Fluorescence loss (ΔF), lesion area (area), and impact (ΔQ) values of enamel surfaces were quantified by QLF-D BiluminatorTM (Inspektor-Pro, Amsterdam, The Netherlands) at baseline and after 7, 14, and 21 days of application of the respective materials. Results ΔF value presented a significantly decreasing trend throughout the 21 days for all groups except the Duraphat and Enamel Pro varnishes. The changes between 14th and 21st days of the Clinpro XT varnish application were significantly higher than Emdogain, Curodont, and Enamel Pro. The Curodont group showed higher lesion area changes between the first and second week in comparison to the Emdogain, Clinpro XT, and Enamel Pro groups, whereas Clinpro XT assured the highest reduction from the second to the third week of the observation period. Conclusions The fluorescence loss was significantly reduced with enamel matrix protein, self-assembling peptide, and light-curable fluoride varnishes in the analysis for 21 days. Curodont and Clinpro XT were effective in diminishing the fluorescence loss and lesion area compared to the Duraphat, Enamel Pro fluoride varnishes, and Emdogain in different time points.

Objectives Adults with fixed orthodontic appliances are increasing nowadays. Compared with adolescents, adults present biological differences that might influence treatment duration. Therefore, the aim of the study was to compare duration of treatment with fixed appliances between adults and adolescents. Materials and methods Eight databases were searched up to September 2019 for randomized and non-randomized clinical studies comparing treatment duration with fixed appliances in adolescents and adult patients. After duplicate study selection, data extraction, and risk of bias assessment with the Cochrane ROBINS-I tool, random effects meta-analyses of mean differences (MD) and their 95% confidence intervals (CIs) were performed, followed by assessment of the quality of evidence with GRADE. Results A total of 11 unique studies (one prospective and 10 retrospective non-randomized) with 2969 adolescents and 1380 adult patients were finally included. Meta-analysis of 7 studies found no significant difference in the duration of comprehensive treatment with fixed appliances (MD = − 0.8 month; 95% CI = − 4.2 to 2.6 months; P = 0.65; I2 = 92%) between adults and adolescents. Similarly, both distalization of upper first molars with skeletal anchorage for class II correction and the retraction of canines into the premolar extraction spaces lasted similarly long among adults and adolescents. On the other hand, alignment of palatally displaced canines lasted considerably longer in adults compared to adolescents (1 study; MD = 3.8 months; 95% CI = 1.4 to 6.2 months; P = 0.002). The quality of evidence for the meta-analysis was low due to the inclusion of non-randomized studies with considerable risk of bias. Conclusions While existing evidence does not indicate a difference in the overall duration of treatment with fixed appliances between adults and adolescents, the alignment of palatally displaced canines lasted significantly longer in adults. However, our confidence in these estimates is low due to the risk of bias in the included studies. Trial registration PROSPERO: (CRD42019148169)

To compare the long-term dentoskeletal effects of early treatment with banded or bonded RME (Rapid Maxillary Expansion)-Face Mask (RME-FM) versus late treatment with bonded Hybrid-Hyrax, alt-RAMEC (Alternate Rapid Maxillary Expansion and Contraction) and intraoral Class III elastics anchored to miniscrew-reinforced-Lower-lingual-Arch (alt-RAMEC-HH-LLA) in growing, maxillary retrognathic patients.Two groups were matched at long-term follow-up retrospectively. Patients received either early RME-FM (n=16, 5 males, 11 females, age T1: 6.5±0.9 years, age T2: 15.8±2.5 years) or late alt-RAMEC-HH-LLA (n=15, 7 males, 8 females, age T1: 12.52±0.94 years, age T2: 16.8±0.9 years). Total follow-up was 9.2±2.3 years and 4.2±0.2 years respectively, including fixed appliances to compete treatment.Both treatments resulted in Class III correction except one unsuccessful case of alt-RAMEC-HH-LLA. Active maxillary protraction was 1.6±0.5years with RME-FM and 0.5 years with alt-RAMEC-HH-LLA being significantly shorter (P0.001). Values at T2 estimation with multivariate linear regression for correlated multiple outcomes, conditional on baseline estimates, age and sex showed alt-RAMEC-HH-LLA inducing significantly more retroclined lower incisors (mean: -6.11°; 95%CI: -10.66, -1.57; P=0.01), less overbite (mean: -1.28mm; 95%CI: -1.79, -0.761; P0.001), less maxillo (Co-A)- (mean: -4.54mm; 95%CI: -7.91, -1.16; P=0.01) mandibular (Co-Gn) (mean: -10.5mm; 95%CI: -17.45, -3.55; P=0.003) projections/size, more open gonial angle (mean: 4.93°; 95%CI: 2.27, 7.59; P0.001), and less S-N length (mean: -5.04mm; 95%CI: -6.57, -3.51; P0.001).Patients treated with either early RME-FM or late Alt-RAMEC-HH-LLA had comparable overall post-pubertal skeletal and overjet corrections. However, the late Alt-RAMEC-HH-LLA showed less correction of dentoalveolar compensations and in particular of the mandibular incisors. The overbite, maxillary and mandibular projection and size were lower and the gonial angle was more open.

Summary Aim To assess the prevalence of a priori power calculations in orthodontic literature and to identify potential associations with a number of study characteristics, including journal, year of publication and statistical significance of the outcome. Materials and methods The electronic archives of four leading orthodontic journals with the highest impact factor (American Journal of Orthodontics and Dentofacial Orthopedics, AJODO; European Journal of Orthodontics, EJO; Angle Orthodontist, ANGLE; Orthodontics and Craniofacial Research, OCR) were assessed over a 3 year period until December 2018. The proportion of articles reporting a priori power calculations were recorded, and the association with journal, year of publication, study design, continent of authorship, number of centres and researchers, statistical significance of results and reporting of confidence intervals (CIs) was assessed. Univariable and multivariable regression were used to identify significant predictors. Results Overall, 654 eligible articles were retrieved, with the majority published in the AJODO (n = 246, 37.6%), followed by ANGLE (n = 222, 33.9%) and EJO (n = 139, 21.3%). A total of 233 studies (35.6%) presented power considerations a priori along with sample size calculations. Study design was a very strong predictor with interventional design presenting 3.02 times higher odds for a priori power assumptions compared to observational research [odds ratio (OR): 3.02; 95% CIs: 2.06, 4.42; P < 0.001]. Conclusions Presentation of a priori power considerations for sample size calculations was not universal in contemporary orthodontic literature, while specific study designs such as observational or animal and in vitro studies were less likely to report such considerations.

The purpose of this critical review is to list the sources of aerosol production during orthodontic standard procedure, analyze the constituent components of aerosol and their dependency on modes of grinding, the presence of water and type of bur, and suggest a method to minimize the quantity and detrimental characteristics of the particles comprising the solid matter of aerosol. Minimization of water-spray syringe utilization for rinsing is suggested on bonding related procedures, while temporal conditions as represented by seasonal epidemics should be considered for the decision of intervention scheme provided as a preprocedural mouth rinse, in an attempt to reduce the load of aerosolized pathogens. In normal conditions, chlorhexidine 0.2%, preferably under elevated temperature state should be prioritized for reducing bacterial counts. In the presence of oxidation vulnerable viruses within the community, substitute strategies might be represented by the use of povidone iodine 0.2%-1%, or hydrogen peroxide 1%. After debonding, extensive material grinding, as well as aligner related attachment clean-up, should involve the use of carbide tungsten burs under water cooling conditions for cutting efficiency enhancement, duration restriction of the procedure, as well as reduction of aerosolized nanoparticles. In this respect, selection strategies of malocclusions eligible for aligner treatment should be reconsidered and future perspectives may entail careful and more restricted utilization of attachment grips. For more limited clean-up procedures, such as grinding of minimal amounts of adhesive remnants, or individualized bracket debonding in the course of treatment, hand-instruments for remnant removal might well represent an effective strategy. Efforts to minimize the use of rotary instrumentation in orthodontic settings might also lead the way for future solutions. Measures of self-protection for the treatment team should never be neglected. Dressing gowns and facemasks with filter protection layers, appropriate ventilation and fresh air flow within the operating room comprise significant links to the overall picture of practice management. Risk management considerations should be constant, but also updated as new material applications come into play, while being grounded on the best available evidence.

BACKGROUND: Although ceramic brackets have been extensively used for decades in orthodontics there is not till today any study focusing on the possible deterioration of mechanical properties after in vivo ageing. OBJECTIVES: To determine whether the mechanical properties of alumina orthodontic brackets change after intraoral ageing thereby assessing the validity of a theoretical model established for the performance of ceramics in wet environments. MATERIALS AND METHODS: Two alumina brackets, one single crystal (Radiance, American Orthodontics, Sheboygan, WI) and one polycrystalline (Clarity, 3M, St. Paul, MN) were included in this study. Ten brackets for each group were collected from different patients after a minimum of 3-month intraoral exposure, whereas as-received brackets of the same manufacturers were used as controls. The specimens were subjected to Raman spectroscopy and were then embedded in epoxy resin and metallographic ground and polished. The mechanical properties of four groups (radiance control: RAC, radiance-retrieved RAR, clarity control: CLC and clarity-retrieved CLR) were determined using instrumented indentation testing according to ISO 14577-2002. The mechanical properties tested were Martens hardness (HM), indentation modulus (EIT), the ratio of elastic to total work, commonly known as elastic index (ηIT), and fracture toughness (KIC). The numerical results were statistically analysed employing two-way analysis of variance (ANOVA) and Tukey multiple comparison test at a = 0.05. RESULTS: Raman analysis revealed that both brackets are made of a-Al2O3 (corundum). No statistically significant differences were found for HM (N/mm2): RAC = 7249 (1507), RAR = 6926 (1144), CLC = 8052 (1360), CLR = 7390 (2393), or for EIT (GPa): RAC = 141 (27), RAR = 139 (23), CLC = 139 (28), CLR = 131 (47). However, significant differences were identified between the two alumina brackets tested for ηIT (%): RAC = 55.7 (4.2), RAR = 54.0 (3.5), CLC = 62.5 (4.4), CLR = 61.8 (4.7), while KIC was measured only for the polycrystalline bracket (Clarity) because of the complicated fractured pattern of the single-crystal bracket. Both brackets share equal HM and EIT before and after orthodontic intraoral ageing. LIMITATIONS: Whereas the study assessed the changes after intraoral exposure per theoretical model, which describes the reduction of critical stress to induce fracture after wetting, long-term intraoral ageing could have induced more pronounced effects. CONCLUSIONS/IMPLICATIONS: The results of this study indicate that 3 months of intraoral ageing do not change the mechanical properties of single-crystal and polycrystalline orthodontic brackets tested, thus indicating that the Griffith theory may not be applied to the case of manufactured ceramic brackets owing possibly to internal defects.

Orthodontic treatment with sequential aligners has seen a considerable surge in the last decades, and is currently used to treat malocclusions of varying severity. To enhance tooth movement and broaden the spectrum of malocclusions that can be treated with aligners, composite resin attachments are routinely bonded with the acid-etch technique on multiple teeth, a process known to impose irreversible alterations of the enamel structure, color, gloss, and roughness. Additionally, this clinical setting introduces a unique scenario of different materials applied in a manner that involves the development of friction and attrition between the attachment and the softer aligner material, all performing in the harsh conditions of the oral environment, which impact the aging of these materials. The latter may give rise to alterations of the aligners and the composite attachments and potential intraoral release of Bisphenol A, a known endocrine disrupting agent. Furthermore, at the final stages of contemporary aligner treatment, the removal of multiple, sometimes bulky, composite attachments with a volume and surface far greater than the remnant adhesive after debonding of brackets, through grinding that might be associated with pulmonary effects for the patient or staff. Because of the extensive enamel involvement in bonding, the release of factors from the attachment-aligner complex during service, the aging of these entities in the oral environment, and the laborious debonding/composite grinding process coupled with the hazardous nature of aerosol produced during the removal of these bulky specimens, appropriate risk management considerations should be applied and an effort to confine the application of multiple composite specimens bonded to enamel to the absolutely necessary should be pursued.

Made available in DSpace on 2020-12-12T02:41:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-05-01 Purpose: To evaluate the effect of surface conditioning methods and aging on the repair bond strength between resin composite and nanoceramic CAD/CAM resin. Materials and Methods: Twenty-four blocks of nanoceramic CAD/CAM resin (NCR) (Lava Ultimate, 3M Oral Care) (10 x 5 x 2 mm3) and resin composite (Filtek Z350, 3M Oral Care) (RC) were made, embedded in acrylic resin, polished (#600, #800, #1200) and randomly divided into 8 groups (n = 12 each) according to surface conditioning methods (air abrasion with 30-μm CoJet [CJ] or air abrasion with 50-μm Al2O3 [AB]) and aging prior to repair (without aging, 24 h in water at 37°C; with aging 6 months in water at 37°C). The blocks were air abraded (20 s, 2.5 bar, 10 mm) using a standardized device. A layer of adhesive resin (Scotchbond Universal) was applied (20 s) and photopolymerized for 20 s. RC cylinders (O = 2 mm; h = 2 mm) were then bonded to the NCR substrates using a Teflon matrix and photopolymerized for 40 s. All specimens were thermocycled (10,000 cycles, 5°C-55°C) and submitted to the shear bond test (50 kgf, 0.5 mm/min) to measure repair strength. Data (MPa) were analyzed using 3-way ANOVA and Tukey's test (α = 0.05). Failure analysis was performed using stereomicroscopy (20X). Results: ANOVA revealed a significant effect of only the material factor (p = 0.00). The group NCR6mCJ presented bond strengths (29.37 ± 5.41) which were significantly higher than those of the NCR24hCJ (20.88 ± 5.74) and RC groups (p < 0.05). The group RC24hCJ (19.71 ± 4.21) presented the lowest shear bond strength (p < 0.05). Failure analysis revealed predominantly type B mixed failures (adhesive+cohesive in the substrate material) except for the groups NCR24hCJ and NCR6mAB, where mainly type C failure (adhesive+cohesive at the RC) was observed. Conclusion: Air abrasion with Al2O3 particles or silicatization with CoJet followed by adhesive resin application are effective surface conditioning methods for the repair of nanoceramic CAD/CAM resin with resin composite. Federal University of Rio Grande do Norte (UFRN) Department of Dentistry São Paulo State University (UNESP) Private Practice São Paulo State University (UNESP) Institute of Science and Technology, São José dos Campos University of Zurich Center for Dental and Oral Medicine Dental Materials Unit Clinic for Fixed and Removable Prosthodontics and Dental Materials Science São Paulo State University (UNESP) São Paulo State University (UNESP) Institute of Science and Technology, São José dos Campos

Introduction This split-mouth trial aimed to investigate the effect of low-level laser therapy (LLLT) on the amount of maxillary canine distalization when applied every 4 weeks over 12 weeks. Methods Twenty-two adolescents and young adults (15 female, 7 male; aged 13-25 years; n = 22) requiring bilateral maxillary first premolar extractions were recruited. After extractions and leveling-alignment, canines were retracted using closed-coil nickel-titanium springs delivering 150 g of force. LLLT was applied to 8 intraoral points on the buccal and palatal sides around the canine root for 10 seconds per point, on day 0, 28, and 56 with the control side receiving sham application. Alginate impressions were taken every 4 weeks on day 0, 28, 56, and 84. The amount of tooth movement, anchorage loss, and canine rotation were measured digitally. Randomization was generated using www.randomisation.com and allocation concealment through sequentially numbered, opaque, sealed envelopes. Participants, operator, and statistic assessor were blinded. Linear regression modeling accounting for clustering within each patient was used to identify differences between LLLT and control sides. Results Twenty-one patients completed the study. The total amount of tooth movement was similar in the LLLT (2.55 ± 0.73 mm) and control group (2.30 ± 0.86 mm), whereas 0.25 mm (95% confidence interval, –0.21, 0.71 mm) of difference was insignificant (P = 0.27). No significant differences were found for anchorage loss (P = 0.22) or canine rotation (P = 0.25). No harms were reported. Conclusions Application of LLLT every 4 weeks did not result in differences in the amount of tooth movement, anchorage loss, and canine rotation during extraction space closure.