European journal of orthodontics最新文献

Objective: to investigate whether a 12-h daily wear protocol can provide similar treatment outcomes to the traditional 22-h protocol in patients undergoing treatment with Invisalign aligners, specifically in those with mild malocclusions.

Null hypothesis: There is no significant difference between the 22-h and the 12-h protocol.

Trial design: Single-centre randomized clinical trial with two parallel arms and a 1:1 allocation ratio.

Participants: 50 adult patients with Class I malocclusion and a maximum Little Irregularity Index (LII) of 2 mm.

Interventions: Group 1 (9 men, 16 women; 38.56 ± 7.57 y) was treated with the 22-h protocol. Group 2 (12 men, 13 women; 37.15 ± 6.23 y) was treated with the 12-h protocol.

Primary objective: to compare the outcomes of 22-h versus 12-h daily wear in Class I patients with mild crowding.

Secondary objective: to compare the intercanine, inter-premolars, intermolar distances, overjet and overbite in T1 and T2 on both groups.

Randomization: randomization sequence was generated with a 1:1 allocation ratio.

Blinding: the measurements in the T1 and T2 scannings were made by a blinded operator.

Results: The maxillary and mandibular Little irregularity index (LII) were significantly corrected with treatment at T2 in both groups. The mandibular LII showed a statistically greater correction in the 22-h group. There was no statistically significant difference between the groups considering maxillary and mandibular intercanine, interpremolar, intermolar widths, overjet, and overbite at T2.

Conclusion: The recommended 12-h daily protocol for orthodontic aligner use can achieve adequate alignment in the maxilla in cases of very mild crowding. However, correction of mandibular irregularity is significantly less efficient with this protocol compared with the 22-h regimen.

Registration: This clinical trial was registered under UTN U1111-1303-5576 at the Brazilian Registry of Clinical Trials (ReBEC).

Background and objectives: The role of occlusion and orthodontic treatment as potential risk factors for temporomandibular disorders (TMD) continues to be a subject of considerable debate within the scientific community. Nonetheless, current evidence suggests that the association between occlusion and TMD is generally weak and inconsistent and therefore should not be overemphasized.

Materials and methods: This article represents the Ernest Sheldon Friel Memorial Lecture presented in 2025 at the 100th Congress of the European Orthodontic Society. It is focused on the critical and updated evaluation of the relationship among occlusion, orthodontics and TMD. Starting from the historical perspective it analyses the role of condylar position, occlusal disharmonies and occlusal interferences as risk factors of TMD and highlights the need to move beyond a narrow mechanical interpretation of occlusion towards a more integrative approach that considers the central nervous system's processing of peripheral stimuli. In this broader context, individual differences in neuromuscular adaptability must be considered to reduce the likelihood of maladaptive outcomes following dental procedures.

Conclusions and implications: Orthodontists should be well-informed about the multifactorial aetiology of TMD, should know the validated diagnostic criteria for TMD and be prepared with evidence-based strategies for patient management at all stages of treatment.

Background: Comparing the mandibular growth patterns of Class I and Class II children offer valuable insights into adolescent growth dynamics that are crucial for planning growth modification procedures.

Aim: To test the null hypothesis of no class differences (Class I vs. Class II) in mandibular growth spurt parameters (size, timing, intensity) versus clinically relevant differences defined as ≥ 5 mm for size, ≥ 1 year for timing, and ≥ 1 mm/year for intensity.

Subjects and methods: Data (Condyle-Pogonion distance) available from the American Association of Orthodontists Foundation Craniofacial Growth Legacy Collection is analyzed. The dataset includes 160 children, 40 each in Class I and Class II groups for both sexes. A three-level Bayesian SITAR model is fitted, incorporating individual- and study-level random effects for all three growth spurt parameters.

Results: The average mandibular size is greater in Class I than in Class II for both males [5.0 mm, 95% CI (3.0, 7.0)] and females [4.4 mm, 95% CI (3.2, 5.7)]. The growth spurt occurs later for Class I than Class II across both sexes [males: 0.6 years, 95% CI (0.3, 0.9); females: 0.6 years, 95% CI (0.2, 0.9)], and the intensity of the growth spurt is slightly greater in Class I than in Class II [males: 0.2 mm/year, 95% CI (0.0, 0.4); females: 0.2 mm/year, 95% CI (0.0, 0.4)]. The results show individual-level variation in size, timing, and intensity parameters across both Class II and Class I.

Conclusions: No evidence found for clinically meaningful class differences in the timing or intensity of the adolescent growth spurt dynamics for either sex. The mandibular deficiency observed in Class II children is established early, during the pre-adolescent growth period. The cumulative deficiency in mandibular size for Class II children worsens with age, which leads to a more pronounced skeletal discrepancy in adulthood. The clinical implications for treatment planning are discussed.

Limitations: Considering the retrospective nature of the historical data analyzed, caution is warranted when generalizing our findings to contemporary populations.

Background: When assessing the effectiveness of interventions, randomized controlled trials (RCTs) are considered to generate the highest level of evidence. The CONSORT 2010 recommendations promote clear and transparent reporting of RCTs. However, to perform a complete analysis of methodological errors and risk of bias that RCTs may be subjected to, the Risk of Bias tool 2 (RoB 2) has been constructed.

Objectives: The aim of this systematic review was to assess the last 55 years of changes in methodological quality of orthodontic RCTs by using the RoB 2 tool.

Search methods: The MEDLINE via Entrez PubMed, Web of Science, and Cochrane library databases were searched for orthodontic RCT publications from 1 January 1968 to 31 December 2024.

Selection criteria: All RCTs on humans in the field of orthodontics were included. Non-randomized trials, animal studies, orthognathic surgery, syndrome patients, CLP patients, sleep apnea, and in vitro studies were excluded.

Data collection and analysis: The quality assessment of the studies was conducted using the Cochrane Risk of Bias Tool (RoB2). The RCTs were divided into three time periods, i.e. before CONSORT 2010, from 2011 to 2016, and from 2017 to 2024.

Results: A total of 3135 RCTs were identified, and after excluding studies not fulfilling the criteria, 1231 RCTs were included in the quality assessment. Publications in the later or latest time-period had a larger number with low risk of bias than early ones. However, significant room for improvement remained since, in the latest time period there were relatively many RCTs with high risk of bias (67.6%). The main factors to high bias were unclear or missing information about 'who generated the random allocation sequence and enrolled participants' (selection bias), whether 'ITT or intention-to-treat' was used (attrition bias) as well as omitting reporting of 'all important harms or unintended effects' (other bias). Another factor was that baseline characteristics were missing (selection bias).

Limitations: The RoB2 tool is complex, and it requires trained individuals to use the tool.

Conclusions: There remains a need to enhance the quality of RCTs in orthodontics. To reduce the risk of bias, researchers should become well-acquainted with RoB2 before developing research protocols and plans. Specifically, use the 'signaling questions of RoB2' as extensively as possible to aid in designing the plans and protocols concerning the trial's conduct and progression.

Registration: PROSPERO: CRD42023390206.

Objective: This study aimed to assess the frequency of distoangulation of mandibular second premolars (MnP2) in individuals with complete unilateral cleft lip and palate, the angular changes of distoangulated MnP2 from the mixed to the permanent dentition, the clinical outcomes after the follow-up period and the frequency of other associated dental anomalies.

Methods: The distoangulation group (DA) was composed of 37 patients (mean age 9.29, SD = 1.24 years, 15 females, 22 males) with distoangulation of MnP2. The control group (CG) was composed of 37 patients (mean age 9.9 years, SD = 1.13, 13 females, 24 males) without distoangulation of MnP2. Digital panoramic radiographs taken in the mixed dentition (T1) and early permanent dentition (T2) were analyzed in both groups. Longitudinal angular changes, the degree of root formation, second premolar depth, and the frequency of associated dental anomalies were analyzed. Intergroup comparison was performed with paired and independent t tests and χ² test (p < 0.05).

Results: The prevalence of MnP2 distoangulation in the mixed dentition was 18.5%. The DA showed a smaller initial distal angle (θ = 56.45° ± 6.72) compared to the CG (78.24° ± 6.09). The most common clinical outcome was the uprighting and spontaneous eruption of the MnP2 observed in 80.0% of the sample. MnP2 distoangulation was significantly associated with deciduous molar infraocclusion, agenesis of maxillary second premolar and ectopic eruption of maxillary first permanent molar.

Conclusion: The frequency of MnP2 distoangulation among individuals with UCLP was 18.5%, with favorable spontaneous uprighting and eruption observed in most cases.

Objectives: To analyze the maxillary arch expansion efficiency and biomechanical mechanisms of clear aligners (CAs) in different dentition developmental stages.

Methods: Four 3D finite element models of maxillary arch expansion with CA were established to represent distinct dentition stages: (A) early mixed dentition (1, 2, C, D, E, 6); (B) late mixed dentition (1, 2, C, 4, E, 6); (C) early permanent dentition (1, 2, 3, 4, 5, 6); and (D) permanent dentition (1, 2, 3, 4, 5, 6, 7). A 0.2 mm buccal expansion in one CA was simulated for the maxillary posterior teeth. 3D displacement of maxillary teeth and von Mises stress distribution in roots were analyzed.

Results: The late mixed dentition showed the greatest mid-arch expansion (0.102 mm) with notable buccal tipping, while the early mixed dentition had the least (0.065 mm). Early permanent dentition demonstrated better torque control, with less buccal tipping of first premolars. Posterior-arch expansion was less pronounced than mid-arch expansion: permanent dentition showed smaller first molar displacement (Group C: 0.016 mm, Group D: 0.027 mm), while mixed dentition exhibited palatal molar displacement (Group A: -0.014 mm, Group B: -0.011 mm). Maxillary incisors displayed labial proclination in mixed dentition but lingual inclination in permanent dentition. The highest von Mises root stress was found in the first primary molar of early mixed dentition (0.134 MPa).

Limitations: The study only analyzes dental expansion and does not take into consideration the sutural maturation status.

Conclusions: The efficacy and biomechanics of CA maxillary expansion differ by different dentition stages in adolescent patients. In mixed dentition, expansion mainly occurs at the mid-arch, with palatal molar displacement and labial incisor tipping. Permanent dentition achieves more effective posterior arch expansion with better torque control compares to mixed dentition. The clinical applicability of these findings requires cautious interpretation.

Background: Clear aligner therapy has become a popular orthodontic treatment, with over 14 million users globally. However, its environmental impact is significant, generating over 1000 tons of plastic waste annually, alongside microplastic contamination and high carbon emissions. Despite digital advancements, recycling rates remain low, ranging from only 12% in Asian clinics to 29% in the EU, underscoring the urgent need for sustainable practices in orthodontics.

Aims: This scoping review aimed to synthesize current evidence on the environmental impact of clear aligner therapy and evaluate sustainable strategies and implementation challenges, guided by the United Nations Sustainable Development Goals (SDGs).

Methods: This review followed PRISMA-ScR guidelines and was registered in the Open Science Framework (Registration ID: pnjd4). Twenty-seven studies from eight countries (2017-25) were analyzed, focusing on sustainability strategies, waste management, and innovations. Data were synthesized thematically using the 4R framework (Reduce, Reuse, Recycle, Rethink) and aligned with relevant sustainable development goals.

Results: Key findings revealed that (i) staged aligner production and digital workflows reduce waste by 30%-41% and lower carbon emissions by 58%; (ii) bioplastics (e.g. silk fibroin) and 4D-printed shape-memory aligners show promise but face cost and material scalability challenges, and (iii) stakeholder collaboration across manufacturing, clinics, and policy is essential. Barriers include inadequate infrastructure and a lack of lifecycle data.

Conclusion: This review fills a critical gap by linking clinical orthodontic innovations to broader environmental and public health goals. Future research must prioritize lifecycle analyses, enzymatic recycling, and AI-driven planning to bridge evidence gaps. By integrating these strategies, orthodontics can balance ecological responsibility with clinical efficacy.

Background: Early management of congenitally missing mandibular second premolars may influence craniofacial growth, yet the long-term effects of extracting the primary second molars remain unclear.

Objectives: To evaluate the skeletal and dental effects of extracting mandibular primary second molars in patients with congenitally missing mandibular second premolars and to compare with historical control data.

Trial design: Prospective, randomized longitudinal split-mouth trial.

Materials and methods: This longitudinal study is based on 40 patients (aged 9-12 years) with bilateral agenesis of mandibular second premolars, who were randomly assigned to either extraction or hemisection of the primary second molar. Randomization to determine the side and order of extraction or hemisection was performed using an online tool, with allocation concealment ensured by sequentially numbered, opaque, sealed envelopes prepared in advance by the author responsible for treatment assignment, who was not involved in patient care. The present study examines the overall treatment effect, regardless of the method applied in the split-mouth design. Cephalometric analyses were performed at baseline (T1) and after 4 years (T2). Dental casts were evaluated at T2 to measure residual space. A control group of 29 untreated individuals with normal occlusion was included for comparison. All measurements were conducted by an independent examiner blinded to the treatment assignment.

Results: In the extraction group both the maxilla and the mandible exhibited forward growth (P < .05), while only minor changes were detected in the control group. Extraction caused significant retroclination of the lower incisors by 4.5° (P < .01) and retrusion by 1.8 mm (P < .01), leading to an increased overjet of 1.2 mm (P < .05) and overbite of 1.5 mm (P < .05). Compared with controls, dental changes were significantly greater in the extraction group (P < .05). Residual space after extraction showed no significant correlation with cephalometric changes.

Conclusion: Extraction of mandibular primary second molars in cases of agenesis induces favourable dental changes without detrimental skeletal effects. This approach may be a viable option in selected patients, although caution is recommended for those with deep bite tendencies.

Trial registration: The trial was registered with https://www.researchweb.org/, registration number: 967125.

Background: Clear aligners represent a modern alternative to traditional fixed orthodontic appliances, offering aesthetic and removable treatment options. However, variability in clinical outcomes and treatment protocols has led to inconsistent evidence regarding their effectiveness and stability.

Objectives: To systematically review and synthesize available evidence from randomized and non-randomized trials comparing the quality and stability of orthodontic treatment outcomes using clear aligners versus fixed appliances.

Search methods: A comprehensive literature search was conducted across seven databases (PubMed®, Google™ Scholar, Embase®, Scopus®, Web of ScienceTM, the Cochrane Central Register of Controlled Trials, ProQuest) up to February 2025, identifying relevant clinical trials assessing treatment outcomes with clear aligners and fixed appliances.

Selection criteria: Randomized controlled trials and non-randomized clinical trials comparing orthodontic treatment outcomes of clear aligners versus conventional fixed appliances in patients undergoing orthodontic treatment were included.

Data collection and analysis: Two reviewers independently screened titles, abstracts, and full texts, extracted data, and assessed the risk of bias for each included study. The Cochrane Risk of Bias tool (RoB2 tool) was used for randomized controlled trials, while the ROBINS-I tool was applied for non-randomized studies. When appropriate, random-effects meta-analyses were performed. The certainty of the evidence for each outcome was evaluated using the GRADE approach.

Results: Fifteen trials involving 1084 patients were included. The risk of bias varied across studies. No significant differences were found in treatment quality or duration between clear aligners and fixed appliances in non-extraction cases, although sensitivity analyses suggested shorter treatment duration with clear aligners. In extraction cases, fixed appliances provided superior treatment quality, attributed to enhanced control of tooth movements. Limited evidence indicated similar post-treatment stability between the two interventions. However, study heterogeneity and short follow-up durations limited the strength of conclusions.

Conclusions: Both clear aligners and fixed appliances effectively achieve orthodontic treatment goals. Case complexity and patient compliance should guide appliance selection. Further large-scale, well-designed trials with long-term follow-up are necessary to define comparative outcomes.

Registration: The protocol for this review was registered with PROSPERO (CRD420251072157) during its initial stages.