Orthodontics & Craniofacial Research最新文献

Orthodontists' interest in paediatric obstructive sleep apnoea (PedOSA) has grown in popularity recently. We have seen growth modification treatment modalities, including maxillary expansion, promising the prevention or cure of PedOSA. Clinical approaches such as palatal expansion and mandibular and maxillary complex advancement have been proposed to manage PedOSA. These hypotheses should be adequately tested before clinical recommendations are formulated. This review aimed to narratively synthesise our current understanding of PedOSA management with craniofacial growth modification alternatives. Basic research on the biological basis of PedOSA has been conducted in animal models. Laboratory-based PedOSA studies wish to provide insight into the molecular biological mechanisms by which human PedOSA affects growth-associated structural and emotional growth and development. In the proposed IH animal model, mandibular growth (especially posterior anteroposterior and transverse dimensions) and condylar head bone density were more sensitive to IH exposure in adolescents but less in juvenile rats. Nevertheless, clear-cut statistical growth differences were limited. This suggests that IH, in this rat model, influenced mandibular morphology and metabolism later than earlier craniofacial growth stages. No impact was found for the maxillofacial complex in any plane of space. The existing human studies on the causes, risk factors, consequences, symptomatology, diagnosis and effects of PedOSA are discussed. However, there is a pressing need for further research to clarify whether craniofacial disturbances are consequences or facilitators of PedOSA. Several hypotheses about the potential impact of impaired craniofacial growth as a facilitator for PedOSA currently circulate.

Objective: To compare the three-dimensional root parallelism (mesiodistally and buccolingually) between orthodontic therapy with the Invisalign clear aligners (CA) and fixed appliances (FA) among the first premolar-extraction patients, using cone-beam computed tomography (CBCT).

Materials and methods: Sixty participants with similar American Board of Orthodontics discrepancy index scores as baseline characteristics were included and divided into CA and FA groups (30 per group). Post-treatment mesiodistal and buccolingual root parallelisms were analysed through CBCT using Invivo 6.0.3 software. Descriptive and analytical statistics were performed with a p < 0.05, considered statistically significant.

Results: Mesiodistal dental root parallelism in the U1-U2 and L1-L2 pairings between CA and FA groups were found to be significantly different with inferior parallelism in the CA group (p < 0.05). Conversely, the U3-U5 and L5-L6 pairings exhibited superior parallelism in the CA group (p < 0.05). However, other pairings, including U1-U1, U2-U3, U5-U6, U6-U7, L1-L1, L2-L3, L3-L5, and L6-L7, showed no significant differences in mesiodistal parallelism between groups (p > 0.05). Regarding the buccolingual dental root parallelism, significant differences were also noted in the U5-U6 and L5-L6 pairings with superior parallelism in the CA group (p < 0.05). However, in the U1-U1, U2-U3, U3-U5, U6-U7, L1-L1, L2-L3, L3-L5, and L6-L7 pairings, no significant differences in buccolingual parallelism were observed (p > 0.05).

Conclusion: In this study, our findings indicate that in cases involving the extraction of first premolars, Invisalign clear aligners may offer comparable or even superior three-dimensional root parallelism compared to fixed orthodontic appliances, with the exception of the mesiodistal dimension in upper and lower incisors, where their performance is less effective.

Introduction: Alveolar bone grafting (ABG) influences facial soft tissue changes, but the precise effects on the nose and upper lip remain unclear. This study used three-dimensional (3D) facial images to evaluate nose and upper lip alterations after ABG. We further enhanced the visualisation of these changes by generating 3D superimpositions, colour maps and deviation analyses of key critical landmarks in these regions.

Materials and methods: Forty patients (8-20 years old) with non-syndromic unilateral cleft lip and cleft palate (UCLP) underwent ABG using the iliac bone from September 2022 to September 2023. Three-dimensional facial images were analysed 1 month before and 3 months after surgery to evaluate the spatial displacement of 18 nose and upper lip landmarks to assess changes after ABG. Colour maps were constructed, and 3D deviation analysis was also performed. Paired sample t tests and Wilcoxon's signed-rank tests were used to analyse alterations.

Results: The 3D analysis uncovered significant forward movement on the cleft side only. This included nasal alar, alar curvature and subalar points. The labrale superius of the upper lip showed similar movement. Conversely, other landmarks showed minimal changes in all directions.

Conclusions: ABG can improve the nasal contour on the cleft side. After ABG, significant forward movement occurs in the cleft side of the nasal alar, alar curvature and subalar regions. Although these changes are minimal, they contribute to the overall improvement in facial aesthetics.

Aim: To examine the immune responses in patients diagnosed as grade C periodontitis during orthodontic treatment.

Materials and methods: Our study included seven orthodontic patients with grade C periodontitis and measured their levels of inflammatory cytokines in gingival crevicular fluid and plasma before orthodontic treatment, during the alignment and levelling phase, and during the detailing and finishing phase. The key signal pathways in the orthodontic process of patients with periodontitis were detected by KEGG analysis.

Results: Studies have shown that orthodontic treatment brings great improvement to patients with grade C periodontitis, and most of the local/systemic inflammatory cytokines can be reduced after orthodontic treatment. Simultaneously, orthodontic treatment can reduce the percentage of IFN-γ⁺ Th1 cells in patients with grade C periodontitis. Through KEGG analysis, the IL-17 signalling pathway and TNF signalling pathway are closely interrelated in the orthodontic treatment of patients diagnosed with grade C periodontitis (p-value < 0.001).

Conclusion: Orthodontic treatment can effectively control the local and system levels of inflammation in patients with grade C periodontitis, with IL-17A and TNF-α as potential distinctive inflammatory markers for orthodontic-periodontal combined treatment in individuals with periodontitis.

Palatal impaction of the maxillary canine is commonly considered as a genetic condition, while the lateral incisor root has been suggested to guide maxillary permanent canine eruption. This review assessed whether agenesis of the maxillary lateral incisor is associated with eruption disturbances of the maxillary canine (displacement or impaction). Unrestricted searches in six databases for observational case-control human studies until May 2024 assessing eruption disturbances of the permanent maxillary canine in conjunction with permanent maxillary lateral incisor agenesis were performed. Study selection, data extraction and risk-of-bias assessment with the Joanna Briggs Institute's tool were performed in duplicate. Random-effects meta-analyses of odds ratios (ORs) with their 95% confidence intervals (CIs) were performed, followed by meta-regressions and sensitivity analyses. Seventeen reports pertaining to 17 case-control studies were included covering 10,155 patients (11.6 year-old/46% male on average). Maxillary lateral incisor agenesis was associated with eruption disturbance of the maxillary canine (17 studies; OR = 3.88; 95% CI = 2.05-7.34; p < 0.001; I² = 58). Lateral incisor agenesis was more associated with canine displacement (7 studies; OR = 7.56; 95% CI = 2.10-27.18; p = 0.008; I² = 57) and to a lesser degree with canine impaction (10 studies; OR = 2.39; 95% CI = 1.28-4.48; p = 0.01). No significant effects of patient age or sex were seen, and the results were robust to study design and precision. The quality of evidence was low due to the inclusion of observational case-control studies with methodological issues and residual confounding. Evidence indicates that permanent maxillary lateral incisor agenesis is associated with eruption disturbances of the permanent maxillary canine, including mainly displacement, but also impaction. Trial Registration: PROSPERO database number: CRD42024549898.

Objectives: Research suggested that racial and gender differences may exist in tooth root development and the prevalence of short root anomaly (SRA). However, data on Asian and specifically Chinese populations were limited. This retrospective study aimed to evaluate the prevalence of SRA and the characteristics of the root-to-crown ratio (R/C ratio) within the Chinese population.

Materials and methods: Modified Lind's criteria were used to measure the crown and root lengths in permanent dentition. A total of 27 142 teeth from 1000 subjects were evaluated using panoramic radiographs. Fisher's exact test was employed to analyse gender differences in SRA. Paired-sample and independent-sample t tests were used to assess the characteristics of R/C ratios.

Results: SRA was observed in 27 patients, with a prevalence of 2.7% and a tooth prevalence of 0.309%. Females had a significantly higher prevalence of SRA compared to males (p < 0.01). SRA was found exclusively in incisors (83.72%) and premolars (16.28%), with the maxillary central incisor being the most commonly affected tooth. Additionally, there were statistical differences in the R/C ratio based on gender and jaw position in the normal groups. The highest R/C ratios were observed in the mandibular second premolars, while the maxillary central incisors had the lowest ratios.

Conclusions: SRA was relatively common in the Chinese population, and clinicians should be aware of its presence. It was more frequently observed in females and shows specificity in tooth position, with the maxillary central incisor being the most commonly affected tooth. Our study provides valuable insights for the early diagnosis and treatment of SRA in the Chinese population.

Objective: This study aimed to evaluate the effects of molar attachment orientation and designed molar vertical movement on molar distalisation using clear aligners. Specifically, the study focused on the impact of vertical forces during upper second molar distalisation.

Materials and methods: A three-dimensional finite element analysis was conducted to simulate upper molar distalisation using clear aligners. Four attachment orientations (0°, 45°, 90° and 135°) were designed. The study included three scenarios: distalisation alone; distalisation combined with intrusion; and distalisation combined with extrusion. The displacement tendencies and stress distribution on the second molar under various attachment orientations and vertical movements were analysed.

Results: Molar distalisation resulted in buccal tipping, distal tipping and intrusion tendency in all models. The molar with 135° attachment orientation exhibited the most significant distal movement under intrusive force, while the one with 45° attachment showed the greatest distal movement under extrusive force. Additionally, greater distal movement was achieved with intrusive force compared to extrusive force, likely due to improved aligner grip on the attachments and teeth during intrusion.

Conclusion: Attachment orientation significantly affects the effectiveness of molar distalisation and vertical movement with clear aligners. The 90° attachment group achieved the most effective molar distalisation. The 135° attachment is more effective under intrusive force, while the 45° attachment is preferable under extrusive force.

The objective of this systematic review was to summarise the existing evidence regarding hyoid bone position and upper airway morphology of children with obstructive sleep apnea (OSA). Electronic searches were carried out in PubMed, Embase, Web of Science, CINAHL and WorldCat databases without any restrictions on language from inception to March 2024. The studies which compared the hyoid bone position and upper airway morphology using lateral cephalograms between children with and without OSA will be included. The methodological quality of the included studies was assessed using Newcastle-Ottawa Scale, and the meta-analysis was conducted utilising random-effects model. Twelve cross-sectional studies and one case-control study were included. One study was rated as low quality, three as medium quality, five as high quality, and four as very high quality. Meta-analysis showed that compared to healthy children, children with OSA tended to have increased distance between hyoid bone and mandibular plane (Hy-MP, MD: 3.33, 95% CI: 1.90 to 4.77, p < 0.00001, I² = 72%), increased distance between hyoid bone and cervical vertebra (Hy-C3, MD: 1.54, 95% CI: 0.62 to 2.46, p = 0.001, I² = 68%), and a smaller airway space behind the soft palate (U-MPW, MD: -3.07, 95% CI: -4.76 to -1.38, p = 0.0004, I² = 68%). Whereas there was no significant difference in inferior posterior airway space between children with OSA and healthy controls (IPAS, MD: -1.51, 95% CI: -3.37 to 0.35, p = 0.11, I² = 71%). In children with OSA, the hyoid bone may exhibit a more anterior and inferior position and the airway posterior to the soft palate demonstrated a narrower dimension. Registration: PROSPERO (CRD42024528171).

Objectives: This study aims to determine the effect of gelatin-simvastatin hydrogel application on bone remodelling during relapse.

Materials and methods: Twenty-four rabbits (Oryctolagus cuniculus) were divided into a control group (n = 12) and a treatment group (n = 12). The lower incisors were subjected to orthodontic force and moved distally by an open coil spring. The force (50 cN) was extended for 1 week and retained in a new position for 2 weeks (stabilisation period). The treatment group received a local gelatin-simvastatin hydrogel administration during stabilisation, and the control group received only gelatin hydrogel. The springs were debonded after the stabilisation phase from both groups to facilitate a relapse. The percentage of relapse was measured in a model study using digital callipers. Levels of OPG and RANKL were analysed using ELISA.

Results: The local application of gelatin-simvastatin hydrogel in the treatment group significantly decreases the relapse percentage and RANKL level. Additionally, the gelatin-simvastatin hydrogel significantly increases the level of OPG and ratio of OPG/RANKL.

Conclusions: Applying gelatin-simvastatin hydrogel in the retention period can induce bone formation, inhibit orthodontic relapse and increase tooth stability (in vivo).

Objective: In Class II elastics treatment, the mandible is subject to sustained protraction. The study aimed to investigate the morphological and histological changes resulting from sustained mandibular protraction, through establishment of a novel model in rat.

Materials and methods: Forty-eight 4-week-old male Sprague-Dawley rats were randomly divided into three groups, including the 50 and 100 cN protraction groups, and the control. In the two protraction groups, NiTi coil springs were fixed between the metal bands on the maxillary incisors and mandibular molars to pull the mandible forward. CBCT scans were taken immediately before (T0), 2 weeks (T1) and 4 weeks (T2) after the traction. Histological and immunohistochemical analyses were performed at T1 and T2.

Results: Increase of the condylar process length and angular process length were significantly larger in the two protraction groups than that in the control; however, the condylar process angle (∠CPA) was significantly reduced by the protraction at T2, leading to decreased condylar height. The protraction decreased the condylar cartilage thickness at T1, which recovered to the control level at T2, with no significant changes detected in the expression of SRY-related high mobility group-box gene 9 (SOX9) and type II collagen (COL II), two chondrogenic markers.

Conclusion: The established rat model is manoeuvrable and reliable, which exerts sustained and measurable mandibular protraction. The sustained protraction increases the lengthening of the mandibular condylar process, but alters its growth direction by causing it to turn downwards.