Age-related mitophagy regulates orthodontic tooth movement by affecting PDLSCs mitochondrial function and RANKL/OPG.

A thorough comprehension of age-related variances in orthodontic tooth movement (OTM) and bone remodeling response to mechanical force holds significant implications for enhancing orthodontic treatment. Mitophagy plays a crucial role in bone metabolism and various age-related diseases. However, the impact of mitophagy on the bone remodeling process during OTM remains elusive. Using adolescent (6 weeks old) and adult (12 months old) rats, we established OTM models and observed that orthodontic force increased the expression of the mitophagy proteins PTEN-induced putative kinase 1 (PINK1) and Parkin, as well as the number of tartrate-resistant acid phosphatase-positive osteoclasts and osteocalcin-positive osteoblasts. These biological changes were found to be age-related. In vitro, compression force loading promoted PINK1/Parkin-dependent mitophagy in periodontal ligament stem cells (PDLSCs) derived from adolescents (12-16 years old) and adults (25-35 years old). Furthermore, adult PDLSCs exhibited lower levels of mitophagy, impaired mitochondrial function, and a decreased ratio of RANKL/OPG compared to young PDLSCs after compression. Transfection of siRNA confirmed that inhibition of mitophagy in PDLSC resulted in decreased mitochondrial function and reduced RANKL/OPG ratio. Application of mitophagy inducer Urolithin A enhanced bone remodeling and accelerated OTM in rats, while the mitophagy inhibitor Mdivi-1 had the opposite effect. These findings indicate that force-stimulated PDLSC mitophagy contributes to alveolar bone remodeling during OTM, and age-related impairment of mitophagy negatively impacts the PDLSC response to mechanical stimulus. Our findings enhance the understanding of mitochondrial mechanotransduction and offer new targets to tackle current clinical challenges in orthodontic therapy.

The role of atypical deglutition in children and adolescents with moderate to severe obstructive sleep apnea syndrome.

This cross-sectional study aimed to assess the prevalence of atypical deglutition (tongue thrust) in children diagnosed with moderate to severe obstructive sleep apnea syndrome (OSAS) and to explore its associations, particularly in relation to the type of dentition (mixed or permanent). The study was conducted over a 5 year period at a paediatric hospital in Paris, France. Children aged 6-18 years with moderate to severe OSAS (apnea-hypopnea index ≥5/h) underwent a comprehensive evaluation, including the recording of demographic data, symptoms of snoring and breathing issues, and otolaryngology examination. The swallowing pattern was assessed and orthodontic evaluations were performed. Cephalometric radiography and pharyngometry tests (pharyngeal collapsibility was computed) were conducted. The study found a high prevalence of atypical deglutition in children with mixed 74% [56-87] or permanent 38% [25-51] dentition. In children with mixed dentition and atypical deglutition, the pharyngeal compliance and lower facial dimensions were increased. In children with permanent dentition, atypical deglutition was associated with more severe OSAS and a lower hyoid bone position. Independent of the type of dentition, atypical deglutition was associated with an increase in the apnea-hypopnea index, an increase in the lower facial dimension, increased pharyngeal compliance, and a more caudal hyoid bone position. Atypical deglutition was strongly associated with increased pharyngeal collapsibility, more severe OSAS and altered facial measurements in children. The findings suggest that identifying atypical deglutition in children with OSAS could help to guide a personalised therapeutic approach, including myofunctional therapy.

The oral microbiota and periodontal health in orthodontic patients.

The oral microbiota develops within the first 2 years of childhood and becomes distinct from the parents by 4 years-of-age. The oral microbiota plays an important role in the overall health/symbiosis of the individual. Deviations from the state of symbiosis leads to dysbiosis and an increased risk of pathogenicity. Deviations can occur not only from daily life activities but also from orthodontic interventions. Orthodontic appliances are formed from a variety of biomaterials. Once inserted, they serve as a breeding ground for microbial attachment, not only from new surface areas and crevices but also from material physicochemical interactions different than in the symbiotic state. Individuals undergoing orthodontic treatment show, compared with untreated people, qualitative and quantitative differences in activity within the oral microbiota, induced by increased retention of supra- and subgingival microbial plaque throughout the treatment period. These changes are at the root of the main undesirable effects, such as gingivitis, white spot lesions (WSL), and more severe caries lesions. Notably, the oral microbiota profile in the first weeks of orthodontic intervention might be a valuable indicator to predict and identify higher-risk individuals with respect to periodontal health and caries risk within an otherwise healthy population. Antimicrobial coatings have been used to dissuade microbes from adhering to the biomaterial; however, they disrupt the host microbiota, and several bacterial strains have become resistant. Smart biomaterials that can reduce the antimicrobial load preventing microbial adhesion to orthodontic appliances have shown promising results, but their complexity has kept many solutions from reaching the clinic. 3D printing technology provides opportunities for complex chemical syntheses to be performed uniformly, reducing the cost of producing smart biomaterials giving hope that they may reach the clinic in the near future. The purpose of this review is to emphasize the importance of the oral microbiota during orthodontic therapy and to use innovative technologies to better maintain its healthy balance during surgical procedures.

Orthodontic retention: Rationale and periodontal implications.

Post-treatment change in the form of true relapse and physiological and maturational effects is common following orthodontics. The unpredictable nature of these manifestations dictates a conservative, near-universal approach to retention. Both fixed and removable forms of retention are popular with the latter constrained by variable levels of adherence particularly in the medium- to long-term. Fixed retention may offer a more predictable means of preservation of orthodontic outcomes; however, this advantage is offset by the requirement for prolonged supervision and the potential for adverse changes including periodontal breakdown. Nevertheless, while examples of severe complications are common, a clear causal relationship between intact, passive retainers and periodontal issues does not appear to exist. Nevertheless, the importance of diligent maintenance and careful supervision during fixed retention, in particular, cannot be disregarded.

LncRNA ADAMTS9-AS2 regulates periodontal ligament cell migration under mechanical compression via ADAMTS9/fibronectin.

BACKGROUND: Periodontal ligament cells (PDLCs) are key mechanosensory cells involved in extracellular matrix (ECM) remodeling during orthodontic tooth movement (OTM). Mechanical force changes the ECM components, such as collagens and matrix metalloproteinases. However, the associations between the changes in ECM molecules and cellular dynamics during OTM remain largely uncharacterized. OBJECTIVES: To investigate the influence of mechanical force on the morphology and migration of PDLCs and explore the interaction between ECM remodeling and cellular dynamics, including the detailed mechanisms involved. METHODS: Human PDLCs (hPDLCs) were subjected to a static mechanical compression to mimic the compression state of OTM in vitro. A mouse OTM model was used to mimic the OTM procedure in vivo. The migration of hPDLCs was compared by wound healing and transwell migration assays. Moreover, expression levels of ADAM metallopeptidase with thrombospondin type 1 motif 9 (ADAMTS9) and fibronectin (FN) in hPDLCs were determined via western blotting, immunofluorescence staining, and enzyme-linked immunosorbent assays. Expression levels of ADAMTS9 and FN in mice were assessed via immunohistochemical staining. Additionally, the relative expression of long non-coding RNA (lncRNA) ADAMTS9-antisense RNA 2 (ADAMTS9-AS2) was assessed via quantitative real-time polymerase chain reaction. ADAMTS9-AS2 knockdown was performed to confirm its function in hPDLCs. RESULTS: Mechanical compression induced changes in the morphology of hPDLCs. It also promoted migration and simultaneous upregulation of FN and downregulation of ADAMTS9, a fibronectinase. The mouse OTM model showed the same expression patterns of the two proteins on the compression side of the periodontium of the moved teeth. RNA sequencing revealed that lncRNA ADAMTS9-AS2 expression was significantly upregulated in hPDLCs under mechanical compression. After knocking down ADAMTS9-AS2, hPDLCs migration was significantly inhibited. ADAMTS9 expression was increased as FN expression decreased compared to that in the control group. Moreover, knockdown of ADAMTS9-AS2 reduced the effect of mechanical compression on hPDLCs migration and reversed the expression change of ADAMTS9 and FN. RNA immunoprecipitation revealed direct binding between ADAMTS9-AS2 and ADAMTS9 protein. CONCLUSION: Our study suggests that mechanical compression induces the expression of ADAMTS9-AS2, which directly binds to ADAMTS9 and inhibits its function, leading to the promotion of downstream FN expression and ECM remodeling to facilitate hPDLCs migration and maintain the stability of the periodontium.

Applications of nanotechnology in orthodontics: a comprehensive review of tooth movement, antibacterial properties, friction reduction, and corrosion resistance.

Nanotechnology has contributed important innovations to medicine and dentistry, and has also offered various applications to the field of orthodontics. Intraoral appliances must function in a complex environment that includes digestive enzymes, a diverse microbiome, mechanical stress, and fluctuations of pH and temperature. Nanotechnology can improve the performance of orthodontic brackets and archwires by reducing friction, inhibiting bacterial growth and biofilm formation, optimizing tooth remineralization, improving corrosion resistance and biocompatibility of metal substrates, and accelerating or decelerating orthodontic tooth movement through the application of novel nanocoatings, nanoelectromechanical systems, and nanorobots. This comprehensive review systematically explores the orthodontic applications of nanotechnology, particularly its impacts on tooth movement, antibacterial activity, friction reduction, and corrosion resistance. A search across PubMed, the Web of Science Core Collection, and Google Scholar yielded 261 papers, of which 28 met our inclusion criteria. These selected studies highlight the significant benefits of nanotechnology in orthodontic devices. Recent clinical trials demonstrate that advancements brought by nanotechnology may facilitate the future delivery of more effective and comfortable orthodontic care.

Risk factors for gingival invagination: A retrospective study.

AIM: This study aimed to identify the risk factors for gingival invagination during orthodontic treatment after premolar extraction. MATERIALS AND METHODS: The medical records of 135 patients who had undergone interdental space closure after premolar extraction were collected, and cone beam computed tomography was performed to determine the presence of gingival invagination. The risk factors were examined using mixed-effects models and generalized propensity score weighting (GPSW) to develop a predictive model. RESULTS: Univariate analysis revealed that the extraction site, buccal bone thickness 4 mm apical to the cemento-enamel junction (MB1), mid-root buccal bone thickness (MB2) and vertical skeletal relationships were related to gingival invagination (p < .05). Furthermore, a subsequent multivariable mixed-effects model analysis indicated a significantly increased risk of gingival invagination at MB1 < 1 mm (p < .001; odds ratio [ORMB1≤0.5mm] = 29.304; 95% confidence interval [CI]: 8.986-93.807; OR0.5

Overview of systematic reviews on periodontal-orthodontic interactions: A comprehensive literature analysis.

The aims of this research were to investigate the methodological quality of systematic reviews on periodontal-orthodontic interactions (i.e. reviews of primary research broadly defined as any including both periodontic and orthodontic components) and to provide a mapping of the researched topics. We searched four major databases (PubMed, Lilacs, Web of Science, and Embase) for systematic reviews of periodontal-orthodontic interactions. We used the AMSTAR-2 tool (the acronym is derived from 'a measurement tool to assess systematic reviews') to assess the methodological quality of the included systematic reviews. Individual AMSTAR-2 ratings were tabulated, and the percentage per item was calculated. To assess the association between the AMSTAR-2 percentage score and the overall confidence in the systematic review results, an ordinal regression model was used. We initially retrieved 973 documents, and 43 systematic reviews were included. Systematic reviews of interventions were the most prevalent (n = 26, 60.5%). Most of the systematic reviews did not report a meta-analysis (n = 25, 58.1%). In addition, most of the studies included in the systematic reviews had an unclear or high risk of bias. Most of the systematic reviews were rated as having critically low or low overall confidence (n = 34, 79.1%). A significant correlation was found between the AMSTAR-2 percentage score and overall confidence in the results. The methodological quality of systematic reviews on periodontal-orthodontic interactions can be improved. The limitations of our study include potential language bias and an arbitrary classification of the topics researched.

Surgical and Camouflage Orthodontic Treatment of Anterior Open Bite: Comparison of Profile Attractiveness.

OBJECTIVE: To evaluate the profile's attractiveness between the different protocols for treating the anterior open bite. METHODS: The sample comprised 39 patients with anterior open bite treated with or without extractions, divided into two groups: The surgical group (G1) comprised 21 subjects (10 males, 11 females) with a mean initial age of 21.86 years (SD = 5.09), treated with fixed orthodontic appliance followed by orthognathic surgery, for a total mean period of 2.53 years (SD = 0.61). The mean overbite was -5.01 mm (SD = 2.50); The camouflaged group (G2) comprised 18 subjects (9 males, 9 females), with a mean initial age of 20.47 years (SD = 4.19), treated only with fixed orthodontic appliance, for a total mean period of 2.56 years (SD = 0.94). The mean overbite was -4.28 mm (SD = 1.15). Lateral photographs from pretreatment and posttreatment were used. These photographs were evaluated by 46 laypeople and 67 dentists, who rated the attractiveness of each profile from 0 (most unattractive profile) to 10 (most attractive profile). Intergroup comparisons were performed with independent t-tests. RESULTS: Both groups presented improvement in the profile attractiveness with treatment (p < 0.001). Before treatment, the profile of the surgical group was significantly less attractive than the profile of the camouflaged group (p < 0.001). The surgical presented a more attractive profile at the final stage than the camouflaged group (p < 0.001). The surgical group showed a greater improvement in profile attractiveness with treatment than the camouflaged group (p < 0.001). CONCLUSION: In the final stage, the surgical presented a more attractive and greater improvement in profile attractiveness than the camouflaged group. The laypeople and dentists judged similarly the initial profile attractiveness.

Artificial intelligence as a prediction tool for orthognathic surgery assessment.

INTRODUCTION: An ideal orthodontic treatment involves qualitative and quantitative measurements of dental and skeletal components to evaluate patients' discrepancies, such as facial, occlusal, and functional characteristics. Deciding between orthodontics and orthognathic surgery remains challenging, especially in borderline patients. Advances in technology are aiding clinical decisions in orthodontics. The increasing availability of data and the era of big data enable the use of artificial intelligence to guide clinicians' diagnoses. This study aims to test the capacity of different machine learning (ML) models to predict whether orthognathic surgery or orthodontics treatment is required, using soft and hard tissue cephalometric values. METHODS: A total of 920 lateral radiographs from patients previously treated with either conventional orthodontics or in combination with orthognathic surgery were used, comprising n = 558 Class II and n = 362 Class III patients, respectively. Thirty-two measures were obtained from each cephalogram at the initial appointment. The subjects were randomly divided into training (n = 552), validation (n = 183), and test (n = 185) datasets, both as an entire sample and divided into Class II and Class III sub-groups. The extracted data were evaluated using 10 machine learning models and by a four-expert panel consisting of orthodontists (n = 2) and surgeons (n = 2). RESULTS: The combined prediction of 10 models showed top-ranked performance in the testing dataset for accuracy, F1-score, and AUC (entire sample: 0.707, 0.706, 0.791; Class II: 0.759, 0.758, 0.824; Class III: 0.822, 0.807, 0.89). CONCLUSIONS: The proposed combined 10 ML approach model accurately predicted the need for orthognathic surgery, showing better performance in Class III patients.

Treatment stability with bonded versus vacuum-formed retainers after 12 months: A randomized clinical trial.

OBJECTIVE: To compare the clinical effectiveness of V-bend bonded retainers (BR) versus vacuum-formed retainers (VFR) regarding their capacity to maintain treatment stability and survival rates after 12 months. MATERIALS AND METHODS: Patients finishing orthodontic treatment were randomly allocated into two groups. The BR group received maxillary and mandibular BRs in the lingual surfaces of the anterior teeth. The VFR group received VFRs right after fixed appliances removal. The patients were evaluated at four time-points: at fixed appliances removal (T0), after 3 (T1), 6 (T2) and 12 months (T3). In each time-point digital models were obtained and analysed with the OrthoAnalyzer™ software. Treatment stability based on occlusal outcomes and retainers' survival rates were evaluated. Intergroup comparisons were performed using Mann-Whitney U-tests. The Kaplan-Meier survival plot and the log-rank test were employed to assess the retainers' survival. RESULTS: Both BR and VFR groups included 25 patients. The groups were comparable regarding their baseline characteristics. Up to 6 months, both retainers were equally effective; however, after 12 months, BRs were more effective in maintaining the incisors' alignment in the maxilla and the mandible compared to the VFRs. No differences were noticed in the intercanine and intermolar widths, overjet and overbite. There were no differences regarding the retainers' survivability in both arches. CONCLUSIONS: BRs were more effective in maintaining the alignment of the incisors in the maxilla and mandible compared to VFRs after 12 months. Both retainers presented the same survival rates after the same period.

Impact of maxillary expansion on the sagittal skeletal and dental parameters of growing Class II patients: A systematic review with meta-analysis.

A "spontaneous" correction of the Class II malocclusion has been described after maxillary expansion (ME) treatment. The aim of the present review was to systematically summarize changes in the sagittal dentoskeletal parameters of growing Class II patients after ME. The study protocol was developed according to the PRISMA statement and registered in PROSPERO before literature search, data extraction and analysis. The PICO model was followed in the definition of the research question, search strategies and study selection criteria. Randomized and non-randomized studies on the sagittal effects of ME published in English language without date restrictions were electronically searched across the Cochrane Library, Scopus and MEDLINE/PubMed databases. Changes in sagittal dentoskeletal cephalometric parameters were analysed. The risk of bias in randomized and nonrandomized studies was assessed using the Rob2 and ROBINS-I tools, respectively. A narrative synthesis was performed, focusing on the investigated population, intervention, comparison, and main outcomes. Pairwise meta-analyses were used to compare the outcomes assessed in subjects who underwent ME versus untreated subjects. Ten studies met the inclusion criteria, four were included in the pairwise meta-analyses due to the presence of a control group. Slight but significant improvements in OVJ (MD: -0.36; 95%; CI [-0.69 to -0.01]; p = .04) and 6/6 molar relation (MD: 1.5; 95%; CI [0.69 to 1.61]; p < .0001) were found in patients who underwent ME compared with untreated subjects, whereas no improvement in skeletal parameters was observed. However, the limitations of a small body of moderate-quality evidence and possible confounding factors should be considered. Evidence on the sagittal skeletal and dental effects of ME in Class II patients is still ambiguous, suggesting the need for more clinical trials, including appropriate control subjects, randomization and blinding during outcome assessment.

Effectiveness of pre-alveolar bone graft orthodontics for patients with non-syndromic complete unilateral cleft lip, alveolus and palate: A systematic review and meta-analysis.

The aim of this systematic review was to compare the effectiveness of pre-alveolar bonegraft (ABG) orthodontics with no orthodontic treatment for patients with non-syndromic unilateral cleft lip, alveolus and palate. All relevant studies from 1946 to October 30, 2022, were identified using several sources including The Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials (CENTRAL), LILACS, Scopus, EMBASE, MEDLINE (Ovid) and EPUB ahead of publications and non-indexed citations. Randomized Controlled Trials (RCT) and Controlled Clinical Trials (CCT) were included. POPULATION: Non-syndromic complete unilateral cleft lip, alveolus and palate patients who have had ABG surgery. INTERVENTION: Orthodontics prior to ABG. Comparison: No orthodontic treatment prior to ABG. PRIMARY OUTCOME: Successful eruption of permanent canines. All articles were screened for the title, abstract and full text independently and in duplicate by 2 reviewers. The quality assessment of RCT was performed using Cochrane's risk of bias tool and the CCT was assessed using ROBINS-I tool. Of the 904 studies retrieved in the search, one RCT and one CCT were included. Both studies were judged as high risk of bias. The results from one study showed a statistically significant increase in bone volume and decreased bone defect post-ABG in the orthodontic treatment group. However, there was no difference with respect to other variables. Both included studies were of low quality. There is not enough evidence to recommend orthodontic treatment pre-ABG for patients with complete unilateral cleft lip, alveolus and palate. Future high-quality studies are required to inform patients and clinicians about the effectiveness of pre-graft orthodontic treatment.

#clearaligners and social media: An in-depth analysis of clear aligners' content on Instagram.

BACKGROUND AND OBJECTIVES: Clear aligners-related posts are popularized on social media platforms to educate patients and peers and to market aligners in dental practices. This study aimed to characterize the account credentials and content of the top-performing posts to understand the spread of clear aligners-related information on Instagram. MATERIALS AND METHODS: This cross-sectional web-based study analysed 13 Instagram clear aligners-related hashtags. Content analysis was performed for the "Top 10 posts" listed under the "Top" section for each hashtag within Instagram, as sorted by Instagram's algorithm. Data were analysed for the poster's background, credentials, role, post format, content, and engagement level ratio. Duplicate posts and those not relevant to clear aligners were excluded. Quantitative and qualitative analyses of the collected data were conducted. RESULTS: A total of 29 192 596 posts mentioned the selected hashtags, of which 130 posts were screened in this study. Most posts were authored by dentists (n = 84), 79.8% of them were orthodontic specialists. Self-promotional posts comprised 90.2%, while educational posts accounted for only 8.9%. Interestingly, the number of likes and comments received on posts by patients (n = 19, median = 112, IQR = 340) was significantly higher than those posted by dentists (n = 84, median = 93, IQR = 81.75) (P = .004). CONCLUSION: More than 29 million posts about clear aligners were identified on Instagram. Orthodontists are the leading authors of aligners hashtags. However, the majority of the posts are self-promotional and have nonfactual information. Social media awareness among orthodontic specialists may help provide more evidence-based content about clear aligners and can act as an interactive networking and health communication platform.

Accuracy and clinical validity of automated cephalometric analysis using convolutional neural networks.

BACKGROUND: This study aimed to assess the error range of cephalometric measurements based on the landmarks detected using cascaded CNNs and determine how horizontal and vertical positional errors of individual landmarks affect lateral cephalometric measurements. METHODS: In total, 120 lateral cephalograms were obtained consecutively from patients (mean age, 32.5 ± 11.6) who visited the Asan Medical Center, Seoul, Korea, for orthodontic treatment between 2019 and 2021. An automated lateral cephalometric analysis model previously developed from a nationwide multi-centre database was used to digitize the lateral cephalograms. The horizontal and vertical landmark position error attributable to the AI model was defined as the distance between the landmark identified by the human and that identified by the AI model on the x- and y-axes. The differences between the cephalometric measurements based on the landmarks identified by the AI model vs those identified by the human examiner were assessed. The association between the lateral cephalometric measurements and the positioning errors in the landmarks comprising the cephalometric measurement was assessed. RESULTS: The mean difference in the angular and linear measurements based on AI vs human landmark localization was .99 ± 1.05°, and .80 ± .82 mm, respectively. Significant differences between the measurements derived from AI-based and human localization were observed for all cephalometric variables except SNA, pog-Nperp, facial angle, SN-GoGn, FMA, Bjork sum, U1-SN, U1-FH, IMPA, L1-NB (angular) and interincisal angle. CONCLUSIONS: The errors in landmark positions, especially those that define reference planes, may significantly affect cephalometric measurements. The possibility of errors generated by automated lateral cephalometric analysis systems should be considered when using such systems for orthodontic diagnoses.

Practices and Perception of Paediatric Obstructive Sleep Apnea Among Orthodontists and Paediatric Dentists in Brazil: A Mixed-Methods Study.

OBJECTIVES: To explore orthodontists' (OTs) and paediatric dentists' (PDs) practices and perceptions regarding the screening and management of paediatric obstructive sleep apnea (OSA). METHODS: This explanatory sequential mixed methods design included OTs and PDs with active clinical practice in Brazil and encompassed a quantitative phase followed by a qualitative phase. In the quantitative phase, a survey assessing OSA screening and management practices was administered to OTs and PDs practicing in Brazil. Information-rich OTs and PDs were interviewed in the qualitative phase. Descriptive statistics and the chi-square test were used to analyse the survey data, while inductive content analysis was applied to the interview data. The results from both phases were integrated and reported narratively. RESULTS: Three hundred eighty-one OTs and PDs completed the survey, and ten of them were interviewed. Nearly half of OTs and PDs administered sleep questionnaires and demonstrated some knowledge about paediatric OSA signs and symptoms. PDs and OTs primarily offered rapid maxillary expansion and functional mandibular advancement for managing selected children with OSA, with OTs being more frequently involved in this task than PDs. OTs and PDs identified several barriers and expressed the need for support regarding access to reliable screening tools and interprofessional care. CONCLUSION: Brazilian OTs and PDs were aware of the main signs and symptoms of paediatric OSA and were somewhat involved in offering oral appliance management options. To further define the role of these professionals, increasing support for dental professionals in OSA management and updating existing clinical guidelines is warranted.

Evaluation of palate morphology in patients treated with leaf expander and hyrax expander: A geometric morphometric analysis.

OBJECTIVE: The aim of this study was to evaluate changes in shape of the palatal vault after maxillary expansion with hyrax expander (HE) and leaf expander (LE), using 3D Geometric Morphometric Analysis. SETTING AND SAMPLE POPULATION: Overall, 250 patients (110 M, 140 F) with maxillary transverse deficiency were selected for this study. In this study, 127 subjects were treated with HE, 123 with LE. MATERIALS AND METHODS: Digital dental models were obtained pre-treatment (T0) and after 12 months from the cementation of the device (T1) and processed by means of a digital scanner. Linear and morphometric analyses were conducted to determine the effects of each appliance on dental measurements and palatal shape, and a multiple linear regression was performed to analyse the influence of anchorage and appliance type on final shape. RESULTS: Morphometric analysis showed that there was a lowering of the palatal vault in the HE group, while in the LE group it remained unchanged: the difference in palatal shape at time T0 and T1 was statistically significant in both treatments (HE vs. LE). In the HE group, the change in shape also included the upper part of the palatal vault in the vertical dimension, while in the LE group the change in shape interested mainly palatal shelves and the lower portion of the palate. CONCLUSIONS: Both LE and HE produce clinically significant changes in the morphology of the palatal vault.

Reconsidering the role of nasolabial angle in premolar extraction decision-making: A case-series study.

OBJECTIVES: To evaluate the impact of changes in upper incisor inclination and position on the alteration of the nasolabial angle (NLA) in a series of cases involving the extraction of four first premolars. MATERIALS AND METHODS: The study included 41 patients who underwent orthodontic treatment with premolar extractions. The patients were divided into two groups based on their pretreatment NLA values: Group 1 (NLA ≤ 100°) and Group 2 (NLA > 100°). Measurements of NLA, U1.NA and U1-NA were obtained before and after treatment and U1-Ls pretreatment measure was registered. Statistical analyses were performed to compare the differences in NLA, U1.NA and U1-NA between the two groups and to evaluate the influence of these variables added to U1-Ls (T1) on NLA changes. RESULTS: The results showed that Group 1 exhibited significant changes in NLA, while Group 2 did not. However, both groups showed significant changes in U1.NA and U1-NA. In Group 1, 80% of the individuals presented an increase in NLA and 20% no changes. In Group 2, 10% presented a decrease, 57% no changes and 33% an increase in NLA values. Multiple linear regression analysis indicated that the group factor had a statistically significant influence on NLA variation. Additionally, in Group 2, a negative correlation was observed between changes in U1.NA and NLA. CONCLUSIONS: The findings suggest that individuals with higher pretreatment NLA values tend to maintain their NLA values even after the correction of upper incisor inclination.

Mandibular second molar extraction: A retrospective cohort study of spontaneous occlusal changes in adolescent patients.

OBJECTIVES: Evaluate long-term spontaneous occlusal changes following L7 extraction in adolescent patients. MATERIALS AND METHODS: Study models of 144 participants (63 males, 81 females) retrospectively assessed prior to L7 extraction (9-16 years old; T1) and following L8 eruption (14-25 years old; T2). All received upper fixed appliances. A sub-group (n = 86) received no lower fixed appliances and acted as controls. Occlusal changes were compared between treatment (lower fixed appliance) and control (no lower fixed appliance) groups using PAR index. At T2, L8 occlusal outcome was assessed using ABO grading system. RESULTS: Mean follow-up period 6 (SD 2) years. At T1, lower scores observed in control group for Lower Anterior (P < .001), Midline (P = .033) and Lateral Segments (P = .040) components. At T2, lower scores continued being observed in control group for Midline (P < .001) and Lateral segment (P = .019) components. Higher decrease in Lower Anterior PAR scores observed in treatment group (<.001) with comparable scores between groups at T2 (P = .057). Similar PAR score changes between groups for Lateral Segments, Overjet and Overbite components. At T2, no significant difference observed in Total PAR score reduction between control (83%) and treatment (82%) groups. Good-to-acceptable occlusal outcome of the L8 observed in 81.55% of cases at T2 with no difference between groups. CONCLUSION: In growing patients with mild mandibular crowding, extraction of L7 followed by upper fixed appliance therapy, leads to favourable occlusal changes over a 6-year follow-up period, with or without lower fixed appliance therapy, being an alternative extraction protocol where lower fixed appliance therapy is not recommended.

Pycnodysostosis: Characteristics of teeth, mouth and jaws.

OBJECTIVES: To describe the clinical and radiographic oro-dental characteristics of patients with pycnodysostosis (PDO). MATERIALS & METHODS: A short interview and clinical examination of seven patients with PDO were performed as well as assessment of the temporomandibular joints and masticatory muscles using the diagnostic criteria for temporomandibular disorders, DC-TMD form. A full set of records were taken including photos and intraoral scan. Finally, existing cone beam computed tomography (CBCT) images and radiographs were also studied. RESULTS: All patients presented with bimaxillary micrognathia, five had a convex profile, and two had a straight profile. In addition, posterior open bite, Angle Class III molar relation with accompanying anterior crossbite and a grooved median palate were common findings. No patient showed symptoms of temporomandibular disorder (TMD) apart from some clicking. Finally, the main radiographic findings were the obtuse mandibular angle, the frontal bossing, the elongation of the coronoid/condylar process and the presence of hypercementosis with obliterated pulp chambers. CONCLUSION: The examined patients with PDO were characterized by dental crowding, malocclusion (anterior crossbite, posterior open bite), hypercementosis, obliterated pulp chambers and deviations in mandibular morphology. In conclusion, patients with PDO have a specific need for dental and orthodontic monitoring with focus on crowding and posterior open bite. The patients will benefit from a long-term orthodontic plan including extractions.