Alejandro Iglesias-Linares

Background: Skeletal Class III (SCIII) malocclusion represents a heterogeneous cluster of craniofacial anomalies characterised by a sagittal mesial discrepancy. It is among the most challenging orthodontic conditions to treat because there is no standardisation regarding subphenotype classification or treatment efficacy prediction. This study aimed to develop a data-driven model to identify novel clinically relevant SCIII subphenotypes, contributing to tailored treatment protocols. Methods: A clinical subphenotypic classification model for SCIII was developed using 12 annotated craniofacial landmarks from lateral cephalometric radiographs of 655 adult SCIII patients of white origin. SCIII subphenotypes were identified by applying generalised Procrustes analysis and unsupervised clustering, and a classification model was developed for predicting subphenotypes for new patients. Cross-validation was employed to demonstrate the robustness of our clustering and classification models. Results: Here we show that our model inferred six distinct subphenotypes that unravelled relevant morphological features in SCIII patients. We further demonstrate the generalisability of our model across ethnicities using an external validation cohort of patients of Korean origin. The identified SCIII subphenotypes exhibit a strong correlation with treatment decision. Conclusions: Our results contribute to the development of an accurate SCIII diagnostic tool (available at https://tools.istars.pt/sciii/ ), moving towards the goal of improving treatment efficacy for this condition.

Orthodontic Treatment and External Apical Root Resorption: A Study on the Worldwide Prevalence - A Scoping Review - Turkish Journal of Orthodontics

Objectives: The aim of this in vitro study was to compare the volumetric changes in the attachment regions of two aligner materials subjected to a cyclic insertion-disinsertion model, as well as the influence of a simulated intraoral environment (SIE) on the disinsertion force of the aligners. Materials and methods: Passive aligners of each material were obtained from two patients with different intraoral conditions (mild and severe crowding). Half of these aligners were immersed in SIE. Three study times were established at 35, 50, and 75 insertion disinsertion cycles. At each study time, the aligners were scanned with a Trios 3 intraoral scanner, and the STL models obtained were superimposed for comparative analysis of the volumetric change. The mean and maximum disinsertion forces were also quantified. Results: An increase in the mean force of disinsertion was observed for both aligner materials after exposure to SIE, with a statistically significant increase observed for material 1 ( p < 0.05). Following exposure to SIE, the aligners exhibited a mean rise in maximum disinsertion force of 56.2% in contrast to their performance under ideal conditions. However, there were no statistically significant differences in volumetric changes regardless of the magnitude of crowding and exposure to SIE. Conclusions: Exposure to SIE adversely affects aligner deformation and disinsertion resistance. The PET-G based polymer demonstrated a consistently greater tendency toward volumetric change than the Polyutherane-based polymer. Clinical relevance: Intraoral aging can significantly affect aligner force and volumetric changes, reducing the predictability of planned tooth movements.

Families studies conducted in different ethnic populations worldwide have helped elucidate the molecular and genetic factors involved in the development of skeletal class III malocclusion. Therefore, the aim of this study is to provide an updated summary. The study followed the JBI Manual for Evidence Synthesis and PRISMA‐scR guidelines. PubMed, Scopus, WOS, Google Scholar and DANS databases were explored using specific strategies. Eligible studies included linkage and genome‐wide analyses, while association studies, case reports and in vivo/in vitro research were excluded. The included studies must have involved at least one family with one or more members exhibiting the skeletal malocclusion phenotypes. An autosomal dominant inheritance pattern with variable penetrance for skeletal class III malocclusions across East Asian, Southeast Asian, Middle Eastern, European and South American populations was identified. In contrast, skeletal class II malocclusions exhibited autosomal dominant and X‐linked inheritance patterns, with a higher prevalence in Eastern Mediterranean and South American populations. Key molecular findings include missense mutations in DUSP6 (c.545C>T and c.1094C>T), which affect mandibular prognathism and maxillary deficiency via the FGF/FGFR and MAPK/ERK pathways. Additionally, mutations in ADAMTS1 (c.742I>T), ADAMTS2 (c.3506G>T) and ADAMTSL1 (c.176G>A) impact mandibular growth through aggrecan metabolism and osteogenesis, disrupting bone remodelling via the EGFR/ErbB signalling pathway. This comprehensive review highlights the complex genetic basis of skeletal malocclusions, provides insights into the underlying molecular mechanisms, suggests potential targets for therapeutic intervention, and contributes to our understanding of the genetic architecture of these conditions.

Objectives: To provide a comprehensive critique of the diagnosis of root resorption using panoramic and periapical radiography, including discussion of the various methods of measurement, severity spectrum, and to shed light on a significant factor predisposing to resorption: treatment duration. Materials and Methods: The articles reviewed involved human subjects undergoing buccal fixed orthodontic treatment, diagnosed by panoramic or intraoral radiographs at the beginning and end of treatment. Treatment duration and external apical root resorption (EARR) had to be recorded to be included in the study. Relevant sources were searched using various platforms including PubMed, Scopus, and WoS. All sources of evidence, regardless of language, were included in the study. Results: The search strategy yielded 704 studies; screening by title and abstract yielded 389 articles for full-text review. Forty studies were finally included and categorized according to the type of radiograph used to diagnose EARR: authors of 18 studies used panoramic radiographs, and authors of 22 studies used intraoral radiographs. Conclusions: In this study, we revealed a lack of agreement among authors concerning the diagnosis and measurement methods of external apical root resorption, resulting in inconsistencies in the results. Additionally, patient- and treatment-related factors, including treatment duration, were found to be inconsistently associated with the development of EARR. Standardization of diagnostic protocols and refinement of measurement techniques are essential to improve the accuracy of orthodontic care.

Objectives: To compare and validate two tridimensional diagnostic methods for quantifying and categorizing external root resorption using an artificial intelligence (AI)-aided, automatic, or manual digital segmentation process. Materials and Methods: 40 teeth were segmented from 10 cone beam computed tomography (CBCT) records from five patients. Stereolithographic files were created, and automatic, manual, or AI-aided segmentation of each incisor was performed by two double-blinded operators. Two quantification methods were used and compared by analyzing final segmented regions of the tooth. This study followed QAREL (Quality Appraisal of Diagnostic Reliability) and COSMIN (COnsensus-based Standards for the selection of health Measurement Instruments) guidelines. Reproducibility was assessed using the Dahlberg formula, coefficient of variation, and intraclass correlation coefficient (ICC) ( P value < .05). Results: Intra- and interobserver correlations were high (ICC: > 0.736; P < .01). Statistically significant differences were found between the two measurement methods for high-quality CBCT images of central incisors, mainly at the level of the apical third. Specific differences were found between methods when root resorption was evaluated in the middle and apical thirds using AI segmentation of the central incisor ( P = .043). When referring to total volume loss of the lateral incisor, differences ( P = .021) were observed between methods when segmented by manual or AI-aided procedures. Highest specificity (100%) was observed for AI-aided segmentation and Method 2 for evaluation of root resorption at the apical third volume. Conclusions: Assessment of root resorption with CBCT is highly dependent on CBCT definition, type of segmentation, and measurement method. Three-dimensional (3D) measurement method described by three landmark points yielded satisfactory results using any tested segmentations.

Objectives: To analyze and summarize the current scientific evidence regarding the clinical predictability of mesiodistal movements of upper and lower molars in patients treated with clear aligners without auxiliary aid. Materials and Methods: This review followed PRISMA guidelines and was registered in PROSPERO (CRD42022357639). Databases were searched up to September 2024. Data extraction was performed independently by two reviewers, risk of bias was assessed using the ROBINS-I tool, and certainty of evidence was evaluated qualitatively using the GRADE tool. Results: 919 articles were identified, and six prospective and retrospective studies met the inclusion criteria, predominantly using the Invisalign system. Upper molar predictability was 61.1 ± 9.1% for movements ranging from 0.45 to 3.2 mm. Lower molar distalization showed lower predictability and molar mesial movement had median predictability rates of 85.6 ± 1.1%. Moderate to serious risk of bias and very low quality of evidence was found. Conclusions: Upper molar distalization using clear aligners appears to be predictable for distalization from 1.5 to 3.2 mm. Anchorage reinforcement or overcorrection should be considered when planning mesiodistal movements. Standardization of the measurement method is necessary to improve efficacy of these systems.

Orthodontic-orthognathic treatment is the standard of care for moderate and/or severe skeletal class III (SCIII) malocclusion. Following orthognathic surgery, morphological changes in the temporomandibular joint structures (TMJ) may contribute to condylar resorption (CR). This systematic review aimed to identify the morphological signs of condylar resorption (changes in the condylar head, position, neck, disk, and joint space) following orthognathic surgery in patients with SCIII compared with those with skeletal class II (SCII) malocclusion. Furthermore, surgical techniques were assessed to investigate the extent to which orthognathic surgery may be related to TMJ disorders and potential muscular changes. A systematic search was conducted using Medline, Pubmed, Scopus, Cochrane Library, Web of Science, and Grey Open literature databases [May 2023; PROSPERO: CRD42021293105)]. Articles that met the eligibility criteria were assessed for quality and the risk of bias using MINORS. A meta-analysis was also conducted. Eleven of the 1014 studies met the eligibility criteria. Of the eligible studies, 10 were considered high-quality. Our results indicated that the incidence of condylar resorption was higher in the SCII group (46.7%) than in the SCIII group (37.2%). The condylar angle was preoperatively higher in the SCII group, and this tendency did not change during the follow-up period. No statistically significant differences in condylar width (95% CI: − 0.62 to 0.43; p = 0.72), height changes (95% CI: − 0.92 to 0.46; p = 0.46), ramus angle (95% CI: − 0.63 to 2.56; p = 0.24) were found between groups. The results suggested that TMJ symptoms were similar between the groups pre- and postoperatively. However, the SCII group showed a higher incidence of anterior disc displacement. Furthermore, postoperative cross-sectional measurements of the lateral pterygoid, medial pterygoid, and masseter muscles were significantly different between the groups. CR could be related to specific skeletal pattern, and the extension of surgical movements may be a risk factor. However, the definition of CR remains vague, and no categorization system regarding SCIII patients has been reported to date.