European journal of orthodontics最新文献

Objective: This prospective controlled study aimed to assess whether changes in mandibular incisor inclination during orthodontic treatment with fixed appliances affect gingival thickness (GT) and the width of keratinized gingiva (WKG), and having as reference an untreated group of participants.

Materials and methods: Forty consecutively recruited adult orthodontic patients and 40 untreated volunteers, matched for age and gender and selected from the same background population serving as controls, were included. Mandibular incisor inclination was measured in lateral cephalograms before treatment commencement (T0) and 1 month before fixed appliances' removal (T1). Gingival thickness was measured using an Ultrasound Device (US) and width of keratinized gingiva (WKG) using a standard periodontal probe within the frames of a full periodontal examination at T0, T1, and 1 year after bracket removal (T2), that is, at about 30 months from T1.

Results: Nineteen females and 21 males in each group [mean age in years (range): intervention group 23.1 (16.8-43.3); control: 21.85 (18.2-43.9)] were analysed. Overall, change in incisor proclination [mean change in Incisor Mandibular Angle Plane-IMPA (ΔIMPA) was 6.35° (SD 5.08°)] was not associated with any significant change in soft tissue thickness and with alterations in WKG. The group receiving fixed appliances did not exhibit thickening or thinning of GT in comparison to the control group; the WKG was reduced in the intervention group in comparison to the untreated group, where it essentially remained unchanged (#41: coeff.: -0.29, P value: .1, 95% CIs: -0.65, 0.06; #31: coeff.: -0.51, P value: .01, 95% CIs: -0.88, -0.14).

Conclusions: Lower incisor proclination during orthodontic treatment does not appear to significantly alter GT and WKG, but orthodontic treatment, overall, leads to reduction of the WKG.

Background/objectives: Mandibular second molar (MdM2) is often lost, and its space is filled with a bridge or implant. MdM2 extraction followed by orthodontic treatment protracting mandibular third molar (MdM3) towards the MdM2 position may overcome the missing of MdM2. The objectives of our study were to describe the outcome of the procedure and examined clinical risk factors such as external apical root resorption (EARR) and alveolar bone loss (ABL), as the indicators of poor orthodontic treatment outcomes.

Materials/methods: This retrospective study included 70 cases in 56 patients who received orthodontic treatment at Tokyo Medical and Dental University Hospital between 2007 and 2018. Multi-bracket appliances were used in all patients for MdM3 protraction. Using linear mixed effects models, EARR and ABL were regressed on various factors, including panoramic and cephalometric variables.

Results: With the mean treatment duration of 1040.4 ± 441.8 days, MdM2 space closure was achieved in 92.8% (65 cases). The ANB angle (P = .023) and the use of temporary anchorage devices (TADs) (P = .021) were significantly associated with the greater EARR, while the mandibular plane angle (P = .033) was associated with the greater ABL. MdM3 protraction using the fixed appliances resulted in the closure of MdM2 space in > 90% of cases without evident root resorption.

Limitation: There is a possibility of residual confounding due to the nature of observational study.

Conclusion/implication: Orthodontic treatment of MdM3 protraction may be a feasible strategy to close the space of the missing MdM2.

Introduction: B-cell lymphoma 6 (Bcl6) inhibits osteoclast differentiation in vitro; however, its role in orthodontic tooth movement (OTM) remains unclear. This study aimed to investigate the role of Bcl6 in OTM of rat molars.

Materials and methods: OTM was performed on the maxillary first molars of male rats using nickel-titanium coil springs (25 gf) for 14 days with or without local injection of FX1 (50 mg/kg), a Bcl6 inhibitor (n = 10 per group). Micro-computed tomography (CT) images were used to analyse OTM distance and bone morphometric parameters. Immunohistochemistry (IHC) determined Bcl6 expression and tartrate-resistant acid phosphatase staining (TRAP) staining assessed osteoclast differentiation. TRAP staining, and reverse transcription-quantitative polymerase chain reaction determined the effect of FX1 (1 μM) on in vitro rat osteoclast differentiation. The effect of FX1 on cell proliferation and Smad4 expression in periodontal ligament (PDL) cells was determined.

Results: Administration of FX1 significantly increased OTM distance and decreased the bone/tissue volume compared with vehicle treatment. IHC staining showed that the vehicle-OTM group had higher expression of Bcl6 than the FX1-OTM group. The number of osteoclasts on the compression side was significantly higher in the FX1-OTM group than that in the vehicle-OTM group. FX1 enhanced osteoclast differentiation and expression of Nfatc1, Dc-stamp, and Ctsk mRNA in osteoclasts in vitro. FX1 significantly promotes PDL cell proliferation in vivo and in vitro.

Limitations: We evaluated only 14 days of OTM.

Conclusions: Bcl6 may play an important role in OTM via modulation of osteoclast differentiation and PDL cell proliferation.

Introduction: Palatal rugae are used as anatomical landmarks on the hard palate, in various clinical applications; in forensics, for insertion of mini-screws, and for superimposition. There is ambiguous evidence on whether they change during orthodontic treatment and to what extent. Therefore, we investigated changes in the shape, complexity, and area occupied by palatal rugae following orthodontic treatment with and without extractions.

Materials and methods: Pre- and post-treatment plaster models of maxillae of 28 cases involving first premolar extractions (17 females and 11 males) and 33 non-extraction cases (19 females and 14 males) were scanned and analysed. All participants were selected from a parent sample via discriminant analysis and represent borderline cases. We applied mesh cropping, ball pivoting, distance mapping, contour cropping of rugae, best-fit superimposition, fractal dimension (FD) analysis, and creation of rugae's convex hull area with Viewbox 4 software. The average distance between the closest points of the outlines of pre- and post-treatment palatal rugae (indicating shape change in the set of rugae), disparity in their pre- and post-treatment FDs (reflecting the complexity of their shapes), area occupied by rugae, arch depth, and size of palatal surface were then computed.

Results: The medians of the average distance between pre- and post-treatment outlines after best-fit superimposition were 0.39 mm (interquartile range [IQR]: 0.34-0.51) and 0.27 mm (IQR: 0.22-0.34) mm for the extraction and non-extraction groups, respectively (P < 0.001). The median pre-treatment FDs were 1.497 (IQR: 1.481-1.521) for the extraction group and 1.481 (IQR: 1.456-1.509) for the non-extraction group, whereas their median post-treatment FDs were 1.502 (IQR: 1.472-1.532) and 1.489 (IQR: 1.469-1.501), respectively. The differences between pre- and post-treatment fractal dimensions were not found to be significant, neither within each group, nor across the groups. On the other hand, the surface area occupied by rugae showed a median increase of 14.7 mm2 (IQR: 0.0-46.5) (P = 0.003) following non-extraction treatment only.

Conclusion: Palatal rugae change shape during orthodontic treatment, but their shape complexity, as measured by fractal dimensions, remains unaltered. Extraction treatment exerts a more pronounced effect in shape change compared to treatment without extractions. Nevertheless, non-extraction orthodontic treatment increases the surface on which rugae lie, as measured by means of the convex hull. Although the alterations may appear minor, it is necessary to exercise caution and prudence when employing rugae for superimposition and forensic dentistry purposes.

Background: The fear of pain during the various stages of orthodontic treatment with fixed appliances is a common concern of patients. Therefore, the present research aimed to thoroughly investigate the impact of bracket architecture on pain perception during active treatment, debonding, and adhesive removal.

Materials: One hundred consecutive patients who completed treatment with one of two bracket systems (2-slot brackets with an integral base or conventional twin brackets with foil mesh) were included in this prospective cohort study. Participants were asked to evaluate the level of pain encountered throughout their orthodontic treatment with the fixed appliances and during bracket and adhesive removal, utilizing a 0-10 numerical rating scale. Two different methods of bracket removal (bracket debonding pliers and Lift-Off Debonding Instrument) and adhesive removal (adhesive removal pliers and rotary instrument) were tested.

Results: Our study found moderate and comparable levels of pain during active treatment in both groups (4.4 ± 1.6 in the 2-slot group and 3.9 ± 1.9 in the Twin group). Debonding of brackets with integral base caused more discomfort compared to conventional twin brackets and using bracket removal pliers elicited more pain sensations than when Lift-Off Debonding Instrument were employed. Patients are likely to prefer adhesive removal methods involving rotary instruments despite the sound and vibrations produced by contra-angle handpiece.

Limitations: The lack of randomization in patient grouping introduces an increased risk of bias.

Conclusions: The results of the present study suggest that the bracket architecture, particularly the construction of the bracket base, affects the level of discomfort experienced during debonding.

Trial registration: ClinicalTrials.gov, NCT06324162, Registered 20 March 2024-Retrospectively registered, https://clinicaltrials.gov/study/NCT06324162.

Objectives: To evaluate whether unilateral functional posterior crossbite in growing children creates an asymmetry in masseter muscle thickness and whether this asymmetry is normalized after crossbite correction.

Materials and methods: Two groups of growing individuals were studied prospectively: (i) a treatment group: children with unilateral functional posterior crossbite, undergoing crossbite correction with maxillary expansion; and (ii) a control group: children without transversal malocclusions and orthodontic treatment. The thickness of the masseter muscles was measured bilaterally using ultrasonographic recordings at three time points: pre-treatment (T0); 9 months after (T1); and 30 months after posterior crossbite correction (T2); and at equivalent time points in the control group. Differences within and between the groups were evaluated using paired and unpaired t-tests respectively.

Results: It was found that the thickness of the masseter muscles in patients with unilateral functional posterior crossbite was significantly thinner on the crossbite side (P = .013) by 0.5 mm. At T1, the masseter muscle of the treated crossbite side was thicker than that of the previous normal side (0.3 mm difference; P = .046) while this difference disappeared at T2 (P > .05).

Limitations: The lack of the inclusion of an untreated posterior crossbite group, and the heterogeneity in appliances used are the principal limitations of this study.

Conclusions: The masseter muscles in untreated individuals with unilateral functional posterior crossbite are thinner in the crossbite side than in the contralateral non-crossbite side. This muscular asymmetry however is eliminated some time after successful treatment of this malocclusion, possibly due to the bilateral symmetrization of the activity of the elevator masticatory muscles.

Objectives: We aimed to characterize a craniofacial skeletal phenotype (CSP) of adult obstructive sleep apnea (OSA) patients from a multidimensional perspective, exploring the impact of transverse skeletal discrepancy (TSD) on multivariable polysomnographic profiles.

Materials and methods: This retrospective, cross-sectional study included 102 adult OSA patients. Sagittal, vertical, and transverse skeletal patterns were categorized on the cone beam computed tomography images. The CSP of OSA patients, characterized by a Class II hyperdivergent pattern, was divided into CSP2D and CSP3D subgroups according to the presence of TSD, and compared with the non-CSP of OSA patients. Both nasal and pharyngeal airway variables were involved for assessment, and 12 polysomnographic variables with a sleepiness symptom variable were used for phenotype-based inter-group comparisons.

Results: The CSP patients revealed greater disease severity than the non-CSP patients (indicated by eight polysomnographic variables), despite being younger (P < .05) and less obese (P < .01). The CSP3D patients with TSD exhibited more severe OSA than the age- and BMI-matched CSP2D patients without TSD, as indicated by nine polysomnographic variables, in relation to smaller nasal airway volume, smaller pharyngeal minimum cross-sectional area, and longer pharyngeal airway length (all P < .05). The probability of multiperspective characteristics among three phenotypes was significantly contrasted in 19 variables.

Conclusions: From a multidimensional perspective, the CSP patients showed greater OSA severity with more vulnerable nasal and pharyngeal airways than non-CSP patients, despite being younger and less obese. Specifically, the CSP3D patients revealed far more severe OSA than the CSP2D patients, indicating the significance of TSD on the polysomnographic profiles.

Objectives: This study determined the prevalence and risks of definite sleep bruxism (SB) among children and adolescents presenting for orthodontic treatment.

Methods: This was a cross-sectional study of 7-16-year-old subjects pursuing orthodontic treatment for the first time. The presence or absence of SB was determined using an overnight mandibular movement monitoring inertial measurement sensor, worn by each participant for two consecutive nights. Data from the sensor were extrapolated, then processed and analyzed to automatically identify rhythmic masticatory muscle activity for SB assessment. SB risks were evaluated from previously validated questionnaires, clinical examinations, lateral cephalometric radiographs, and digital study models.

Results: A total of 87 subjects with a mean age of 12.82 years ± 2.24 and body mass index of 21.45 ± 5.49 participated in the study. The prevalence of SB was 60.7%. Multiple linear regression analysis revealed that SB had statistically significant association with microarousals (events/h) (β=0.31, 95% Confidence Interval [CI] 0.25-0.36, P < .001) and maxillary 6-6 dimension (mm) (β = 0.08, 95% CI 0.02-0.13, P = .008). A second model excluding microarousals showed that SB had a statistically significant association with sleep efficiency (SE) percentage (β = -0.15, 95% CI -0.28 to -0.01, P = .026) and obstructive respiratory disturbance index (ORDI) (events/h) (β = 0.33, 95% CI 0.15-0.51, P < .001).

Conclusions and implications: In a growing orthodontic population, definite SB is very common. SB is related to microarousals, maxillary intermolar width, SE percentage, and ORDI.

Objectives: This study aimed to determine the genetic and environmental contributions to phenotypic variations of palatal morphology during development.

Methods: Longitudinal three-dimensional digital maxillary dental casts of 228 twin pairs (104 monozygotic and 124 dizygotic) at primary, mixed, and permanent dentition stages were included in this study. Landmarks were placed on the casts along the midpoints of the dento-gingival junction on the palatal side of each tooth and the mid-palatine raphe using MeshLab. Palatal widths, depths, length, area, and volume were measured using those landmarks. Univariate genetic structural equation modelling was performed on twin data at each stage of dental development.

Results: Except for anterior depth, all palatal dimensions increased significantly from the primary to permanent dentition stages. The phenotypic variance for most of the palatal dimensions during development was best explained by a model, including additive genetic and non-shared environment variance components. Variance in volume and area in the primary dentition stage was best explained by a model including additive genetic, shared environment, and non-shared environment variance components. For posterior palatal depth and width, narrow-sense heritability estimates were above 0.8 for all dental developmental stages. In contrast, heritability estimates for other palatal traits fluctuated during development.

Limitation: This study was limited to twins of European ancestry.

Conclusions: Additive genetic and non-shared environmental factors primarily influenced palatal morphology during development. While the genetic influence on different aspects of the palate varied throughout development, it was particularly strong in the posterior region of the palate and during the permanent dentition stage.

Background: The infrazygomatic miniscrew implants (IZC-MSI) serve as innovative temporary anchorage devices placed parallel to the roots of molars in the infrazygomatic crest region, leveraging their extra-radicular location to support the en masse distalization and intrusion of the maxillary dentition. The efficacy and stability of these screws are crucial for their application in contemporary orthodontic practices.

Objectives: This systematic review aimed to estimate the success rate and factors affecting the stability of IZC-MSI.

Search methods: An electronic search was conducted on 7 February 2024 across the following databases: PubMed, Scopus, EMBASE, and Cochrane databases without any restriction on language and time of publication.

Selection criteria: The review included clinical trials (both randomized and non-randomized) and retrospective cohort studies that utilized infrazygomatic miniscrew anchorage for orthodontic tooth movement in human participants.

Data collection and analysis: The proportion of success rate was calculated and factors affecting stability (patient and implant-related factors) such as age, sex, implant position, and loading characteristics were subjected to subgroup analysis and meta-regression. The quality assessment of studies was done using the Cochrane risk-of-bias tools for randomized (RoB 2.0) and non-randomized trials (ROBINS-I).

Results: Fourteen studies (n = 1683 IZC-MSI) were included in the meta-analysis revealing a 92% success rate of IZC-MSI (C.I. 87%-95%; prediction interval: 66%-99%; I2 = 80%). Studies with sample size > 100 presented a 94% success rate (C.I. 91%-96%; I2 = 63%) and moderate heterogeneity. Meta-regression analysis revealed no significant relation between age and success rate. Significant heterogeneity was observed in the subgroup analysis of host-, implant- and other related risk factors affecting stability and limited correlation was found. The risk-of-bias assessment revealed high risk in five, moderate in five, and low in four studies.

Conclusions: IZC-MSI have shown a good success rate for their clinical application. Although some factors appear to influence IZC-MSI stability, the majority of them necessitate additional investigation due to the low quality of evidence. Furthermore, high-quality studies are needed to confirm the results of this meta-analysis and address other important factors such as operator's experience, insertion torque, and sinus penetration that could not be analysed due to limited data.

Registration: CRD42024469048.