Late-forming supernumerary teeth: A case series.

The aim of this case series was to illustrate the development of late-forming supernumerary teeth (LFST) and highlight the implications for orthodontic treatment. There are limited studies relating to the aetiology, prevalence and treatment of LFST and the cases presented here demonstrate the management of LFST within a tertiary care centre. Five cases are presented, which show various presentations and chronological ages in the development of LFST. This case series emphasises the significance of maintaining a low threshold for suspecting LFST in patients where supernumerary teeth have previously been identified. It also highlights the importance of regular clinical and radiographic reviews. Timely identification can help prevent complications and optimise treatment outcomes.

Effects of an Educational Intervention Program on Positional Cranial Deformity in Premature Infants.

Positional cranial deformities are associated with prematurity evolving during the first 2 years of life due to the malleable characteristics of the skull, the first year being the main/primary therapeutic window for intervention. The objectives were (a) to describe health characteristics, peri- and postnatal pathologies, and positional cranial deformities in infants enrolled in an early intervention program and (b) to analyze the effects of a parent education-based intervention program on positional cranial deformity in premature infants. A quantitative, analytical, longitudinal study was conducted. It included 103 premature infants enrolled in an early intervention program (EIP) during the year 2017, all under 4 months of corrected age, to whom a parent education-based intervention program was applied. Cranial circumference, cranial width, diagonals, and anteroposterior diameter were measured, and the cranial asymmetry index (CAI) and cephalic index (CI) were calculated at baseline and during two subsequent evaluations separated by a 3-month period. The main results showed that 75.7% of the infants belonged to a very premature gestational age category, and 57.3% had an adequate weight for gestational age. The most frequent pathologies were premature jaundice, premature anemia, and hyaline membrane disease. The most frequent positional cranial deformity was plagiocephaly. The parent education-based intervention program resulted in (1) a significant decrease in the CAI and a significant increase in the IC, (2) plagiocephalies: an increase in the mild category and a decrease in the moderate + severe categories, (3) brachycephalies: a decrease in the absence category and an increase in the moderate + severe category, and (4) dolichocephalies: an increase in the absence category and a decrease in the mild category. In conclusion, the recommended first line of intervention was not enough for this population, and future studies should support the development of national clinical guidelines, where education is complemented with other therapeutic measures.

Fully automated landmarking and facial segmentation on 3D photographs.

Three-dimensional facial stereophotogrammetry provides a detailed representation of craniofacial soft tissue without the use of ionizing radiation. While manual annotation of landmarks serves as the current gold standard for cephalometric analysis, it is a time-consuming process and is prone to human error. The aim in this study was to develop and evaluate an automated cephalometric annotation method using a deep learning-based approach. Ten landmarks were manually annotated on 2897 3D facial photographs. The automated landmarking workflow involved two successive DiffusionNet models. The dataset was randomly divided into a training and test dataset. The precision of the workflow was evaluated by calculating the Euclidean distances between the automated and manual landmarks and compared to the intra-observer and inter-observer variability of manual annotation and a semi-automated landmarking method. The workflow was successful in 98.6% of all test cases. The deep learning-based landmarking method achieved precise and consistent landmark annotation. The mean precision of 1.69 ± 1.15 mm was comparable to the inter-observer variability (1.31 ± 0.91 mm) of manual annotation. Automated landmark annotation on 3D photographs was achieved with the DiffusionNet-based approach. The proposed method allows quantitative analysis of large datasets and may be used in diagnosis, follow-up, and virtual surgical planning.

Three-dimensional facial soft-tissue changes after surgical orthodontics in different vertical facial types of skeletal Class III malocclusion: A retrospective study.

The study compared the soft-tissue response to hard-tissue movement among different Class III vertical facial types after orthognathic surgery (OGS). The study included 90 consecutive adult patients with skeletal Class III malocclusion who underwent two-jaw OGS. Patients were divided into three groups (high, medium, and low angle) based on the presurgical Frankfort-mandibular plane angle. Cone-beam computerized tomographs were taken before surgery and after debonding. Soft- and hard-tissue linear and angular measurements were performed using three-dimensional reconstruction images. One-way analysis of variance was used for intergroup comparisons. Soft tissue tended to respond more to hard-tissue movement in the lower lip area in patients with low angle (mean = 0.089, SD = 0.047, p = 0.023), whereas no significant difference was observed for other sites. Consistently, L1/Li thickness increased most significantly in the high-angle group (mean = 1.98, SD = 2.14, p = 0.0001), and B/Si thickness decreased most significantly after surgery (mean = 2.16, SD = 2.68, p = 0.016). The findings suggest that the high-angle group had a higher chance of undergoing genioplasty to enhance chin contour. Different OGS plans should be considered for different Class III vertical facial types.

Accuracy and tracing time of cephalometric analyses on a tablet or desktop computer : A prospective study.

BACKGROUND: This prospective study aimed to evaluate the influence of the computer type (tablet or desktop) on accuracy and tracing time of cephalometric analyses. METHODS: Dental students used a web-based application specifically developed for this purpose to perform cephalometric analyses on tablet and desktop computers. Landmark locations and timestamps were exported to measure the accuracy, successful detection rate and tracing time. Reference landmarks were established by six experienced orthodontists. Statistical analysis included reliability assessment, descriptive statistics, and linear mixed effect models. RESULTS: Over a period of 8 semesters a total of 277 cephalometric analyses by 161 students were included. The interrater reliability of the orthodontists establishing the reference coordinates was excellent (ICC > 0.9). For the students, the mean landmark deviation was 2.05 mm and the successful detection rate for the clinically acceptable threshold of 2 mm suggested in the literature was 68.6%, with large variations among landmarks. No effect of the computer type on accuracy and tracing time of the cephalometric analyses could be found. CONCLUSION: The use of tablet computers for cephalometric analyses can be recommended.

Divergence between CBCT and Optical Scans for Soft Tissue Analysis and Cephalometry in Facial Imaging: A cross-sectional study on healthy adults.

BACKGROUND: Facial soft tissue analysis is becoming increasingly emphasized in orthodontic diagnosis and treatment planning. While traditional cephalometry primarily focuses on hard tissues, recent non-invasive imaging techniques offer the potential to comprehensively evaluate three-dimensional (3D) facial soft tissues. The aim of the study was to establish the geometrical 3D and cephalometric divergence between Cone Beam Computed Tomography (CBCT) derived images and scanned soft tissues. Crucial for enhancing orthodontic diagnosis, minimizing patient exposure to ionizing radiation and providing facial cephalometric parameters. MATERIAL AND METHODS: A cross-sectional study was conducted from January 2020 to May 2023. CBCT and 3D facial scans were obtained simultaneously using a specialized imaging system. Reproducible landmark points were selected for both cephalometric and soft tissue analysis. Angular and linear measurements were recorded, and correlations between CT and facial scans were statistically assessed. RESULTS: Comparisons between 10 CBCT-derived and 10 facial scan-based soft tissue representations resulted into 1.8mm mean root median square (RMS). Angular measurements, such as ANB, right gonial angle, and left gonial angle, exhibited a 0.9° of difference with their respective soft tissue variables. In contrast, linear measurements of total anterior facial height showed a lower correlation coefficient, equal to 0.51. The correlation between soft tissues and underlying hard tissues was more pronounced for gonial angles. CONCLUSION: Facial soft tissue analysis using either 3D facial scans or CBCT-derived offers similar results for orthodontic diagnosis and treatment planning. These findings support the use of non-invasive diagnostic tools in orthodontics, although further investigations are needed to comprehensively understand the complexity of hard and soft tissue relationships.

Diagnostic accuracy of conventional orthodontic radiographic modalities and cone-beam computed tomography for localization of impacted maxillary canine teeth.

BACKGROUND: Orthodontic treatment planning for an impacted canine tooth requires accurate information about its position. The aim of this study was to compare the diagnostic accuracy of two conventional orthodontic radiographic modalities with cone-beam computed tomography (CBCT) for localization of impacted maxillary canine teeth. MATERIALS AND METHODS: Panoramic radiographs, lateral cephalograms, and CBCT scans of 30 patients with unilaterally impacted maxillary canine teeth were retrieved from the archives. Eight expert orthodontists evaluated the parameters related to the location of impacted canine teeth by using panoramic radiographs and lateral cephalograms of patients. After 4 weeks, the same parameters were evaluated on CBCT scans of patients. The diagnostic accuracy of conventional modalities and CBCT was compared with each other and also with the gold standard. RESULTS: The conventional radiographic modalities and CBCT had similar accuracy for assessment of the overall inclination (p = 0.11), apex morphology (p = 0.18), and mesiodistal position of the apex (p = 0.12). CBCT had significantly higher accuracy for determination of incisal tip location (p = 0.001), labiopalatal (p = 0.001) and vertical (p = 0.01) position of the crown tip, minimum bone thickness covering the crown (p = 0.001), and root resorption of the adjacent tooth (p = 0.001). CONCLUSION: The combination of panoramic radiographs and lateral cephalograms was sufficiently accurate to assess some diagnostic parameters such as overall inclination, apex morphology, and mesiodistal apex location of impacted canine teeth.

Comparative Evaluation of Relapse After LeFort 1 Osteotomy in Cleft Palate and Non-cleft Individuals: A Longitudinal Study.

PURPOSE: The aim of this study was to assess and compare the likelihood of relapse one year after LeFort I advancement surgery in patients with and without cleft lip and palate. METHODS: A retrospective observational study which included two groups of participants who underwent LeFort I maxillary advancement was performed. Group 1 included 10 non-cleft subjects and Group 2 included 21 subjects with cleft palate. These maxillary deficient patients were chosen and operated using a technique where only a sagittal displacement was intended. Patients who underwent additional mandibular surgery, significant vertical or transverse alterations, or both were excluded. Pre-operative (T1), immediately post-operative (T2), and minimum one-year follow-up (T3) lateral cephalograms were studied for each group. Skeletal stability and dental stability after LeFort I surgery at a minimum of one-year follow-up in cleft palate and non-cleft patients were evaluated. RESULTS: For the given sample size, relapse tendencies showed statistically significant differences between cleft palate patients and non-cleft palate patients after maxillary advancement. The sella nasion angle and horizontal overlap of the maxillary and mandibular incisors (overjet) decreased by 2 degrees and 0.9 mm respectively in the cleft palate group while decreasing by 1.10 degrees and 0.40 mm in the non-cleft group. CONCLUSIONS: After maxillary advancement with LeFort I osteotomy and miniplate fixation in patients with cleft palate and non-cleft patients, some degree of relapse was detected in both groups for the given sample size after one year post-operatively. The cleft palate group displayed additional relapse tendencies when compared to the non-cleft group.

The relationship between eye canting and vertical craniofacial skeletal asymmetry in adult patients with dento-maxillofacial deformities.

BACKGROUND: Whether eye canting in patients with asymmetric dento-maxillofacial deformities is the result of anatomical asymmetry or a compensatory head position remains controversial. OBJECTIVE: This cross-sectional study aims to verify whether eye canting is correlated with craniofacial skeletal asymmetry. METHODS & MATERIALS: This study was performed by measuring the computed tomographic scans of 223 patients with dento-maxillofacial deformities in Mimics 21.0 software. First grouping was determined based on the intersection angle between the line passing through bilateral lateral canthus point and Frankfurt horizontal plane, and final grouping was based on measurements of the pregroups. RESULTS: The patients were finally categorized into three groups: symmetry group (n = 163), asymmetry subgroups 1 (n = 33) and asymmetry subgroups 2 (n = 27). The results of multiple linear regression and comparisons among groups suggests the presence of orbital skeletal asymmetry in patients with eye canting and the eye canting is partly increment dependent of orbital skeletal asymmetry when using bilateral ears as the reference. The result also reveals that there is a greater angle between the line through bilateral ocular landmarks and the line through the bilateral ear landmarks in patients with ocular canting compared to patient without eye canting. CONCLUSION: Patients with asymmetric dento-maxillofacial deformities and with eye canting have vertical asymmetry of the orbital and cranial skeletal landmarks. These symmetry differences between the eyes and ears may affect the overall craniofacial symmetry after orthognathic surgery.

Cephalometric analysis of patients with beta thalassemia receiving fetal hemoglobin induction therapy.

Objective: We aimed to determine the effects of fetal hemoglobin induction therapy in restricting or even reversing the cephalometric changes associated with beta thalassemia. Materials and methods: In this comparative observational study, 90 participants were equally divided into three groups: a control group; patients with thalassemia major receiving blood transfusion (BT group); and patients receiving induction therapy (i.e., hydroxyl urea (5-10 mg/kg/day) or as much as 20 mg/kg/day) and thalidomide (2-10 mg/kg/day) along with blood transfusion (IT group). All patients underwent history taking and examination, photographic assessment, and radiographic evaluation with a lateral cephalogram. One-way ANOVA followed by post-hoc Tukey test was used to determine differences among groups. Results: The IT group differed significantly from the BT group in all photographic and skull table parameters, and most cephalometric parameters, such as facial angle (p ≤ 0.001), middle and lower facial heights (p ≤ 0.001), and inter-incisal angle (p = 0.036); the mean values in the IT group were similar to those in the control group. In-addition, dental and soft tissue measurements significantly differed among groups. For most parameters, the mean difference indicated higher values in the BT group. Conclusion: Induction therapy appeared to improve the facial angles, heights, and inter-incisal angles, whereas a class II skeletal pattern was observed in the transfusion only group. These findings suggest that fetal hemoglobin induction therapy might have restricted some of the cephalometric changes in patients with beta thalassemia.

Third molar angulation and retromolar space after functional orthodontic treatment : Evaluation of panoramic radiographs after monoblock or Herbst appliance.

PURPOSE: The aim of this respectively cohort study was to evaluate the lower second and third molars and canine angulations, retromolar space and occlusal relationships after functional orthodontic treatments with the monoblock or Herbst appliance using panoramic radiographs. METHODS: Pre- and posttreatment cephalometric and panoramic radiographs of 133 patients (mean age 13.89 ± 1.14 years) treated non-extraction with monoblock (n: 44), Herbst (n: 45) and fixed orthodontic appliances (control group; n: 44) were included to the study. Dental and skeletal measurements were performed on cephalometric radiographs. The angle between the third and second molars, and canines with the lower border of the mandible and the occlusal plane, gonial angle, the angle between the third and second molars and the retromolar space width were assessed on pre- and posttreatment panoramic radiographs. Paired and independent t tests were used for the statistical analysis of the data for intragroup and intergroup comparisons. RESULTS: Functional treatment with both the monoblock and the Herbst appliances resulted in improvement of skeletal class II relationships. Retromolar space significantly increased in the functional appliance groups compared to the control group (p ≤ 0.001), but improvement of the angulations of posterior teeth was significant only in the monoblock group (p ≤ 0.001). CONCLUSION: While both the Herbst and monoblock appliances led to an increase in retromolar space, monoblock treatment resulted in more favorable angulation of the third molars compared to the Herbst treatment.

Occlusal Outcomes in Non-Robin Sequence Patients with Isolated Cleft Palate.

OBJECTIVES: 1. To assess the skeletal class occlusion and lateral cephalometry in children with isolated cleft palates (non-Robin sequence) and 2. to identify associations between these findings and pre-palatoplasty cleft palate measurements. STUDY DESIGN: Retrospective cohort study. SETTING: North American Institutional Tertiary Paediatric Center. PATIENTS: Our cleft database was reviewed, and patients were included if they had an isolated cleft palate without a Robin Sequence diagnosis, had a Furlow palatoplasty and had available per operative cleft palate measurements and available lateral cephalogram between 6 and 8 years old. Thirty-two patients matched to inclusion criteria. INTERVENTION: Furlow's Palatoplasty. MAIN OUTCOME AND MEASURES: Cleft size at palatoplasty, cephalometric measurements and skeletal occlusal classes were analysed. ANOVA was used to test the association between cephalometric measurements and occlusal classes. Results are presented as means with a 95% confidence interval. The association between cleft measurements and cephalometric parameters was tested with Spearman Correlation (rs). RESULTS: The skeletal occlusal outcome at 7 years old for this series of patients was: Class I: 19%; Class II: 59% and Class III: 22%. No single cleft measurement at palatoplasty was predictive of the skeletal occlusal outcome. A larger hard palate cleft was associated with a shorter antero-posterior maxilla. CONCLUSIONS: The skeletal occlusal class outcomes were similar to those found in a previous study in the literature. The occlusal prognosis appears to be better than in patients with Robin Sequence or with an associated cleft lip. No preoperative measurement was found to be associated with the occlusal outcome.

Vertical cephalometric characteristics in different populations with Turner syndrome as compared to non-syndromic populations: A meta-analysis.

AIMS: The present aim was to evaluate vertical cephalometric characteristics in populations with Turner syndrome (TS) using meta-analysis methodology. METHODS: Six electronic databases were queried, up to August 2023, to identify studies comparing the vertical cephalometric characteristics in populations with TS, compared to female control groups. Data were extracted from eligible studies and random-effects meta-analysis was employed. Subgroup meta-analyses for age and karyotype were also attempted. Risk of bias was assessed using a modified version of the AXIS tool. RESULTS: From the initial 195 studies identified, 17 were included in the quantitative synthesis, resulting in a sample of 417 patients with TS, originating from 10 different countries. Risk of bias was overall questionable. Mandibular ramus height was found to be smaller in females with TS, along with a reduction in posterior facial height, a larger anterior-posterior facial height ratio, and an increase in the mandibular plane angle. Subgroup meta-analyses showed that females with the monosomy X karyotype had vertical cephalometric characteristics which deviated more from the norm than those with other karyotypes. CONCLUSION: The vertical lateral cephalometric characteristics of females with TS differ significantly from those of non-syndromic females, with the largest and most consistent deviation being seen in the monosomy X karyotype. Females with TS show less craniofacial posterior vertical development, with an evident reduction in mandibular ramus height leading to the cephalometric characteristics observed.

Long-term evaluation of condylar positional and volumetric parameters and skeletal stability in Class III bimaxillary orthognathic surgery patients.

This retrospective study examined long-term (4-5 years) condylar positional and volumetric changes and skeletal stability after bimaxillary orthognathic surgery in skeletal Class III patients. Pre-surgical (T0: 0.9 ± 1.1 months) and post-surgical (T1: 0.6 ± 0.7 months; T2: 12.8 ± 3.1 months; T3: 56.5 ± 6.5 months) cone beam computed tomography (CBCT) images of 22 patients were obtained. CBCT multiplanar reformation (MPR) images were generated, and three-dimensional (3D) condylar models were constructed and superimposed to compare changes in condylar volume from pre- to postoperative. Condylar position in the sagittal and coronal planes altered immediately after surgery; however at long-term follow-up, the condyles had returned to their pre-surgical position. The condyles remained slightly inwardly rotated at short-term (-2.6°, 95% confidence interval -3.5° to -1.7°) and long-term (-1.9°, 95% confidence interval -2.8° to -1.0°) follow-up. Changes in condylar volume were insignificant after surgery. Condylar positional changes had no effect on skeletal stability. However, patients with an increased face height prior to surgery and more retrusive jaw position postoperatively were more prone to condylar resorption. Surgical changes remained stable 4-5 years after surgery. In conclusion, condylar position changed insignificantly following surgical correction in Class III patients provided that the correct surgical technique was employed.

Volumetric comparison of mandibular condyles and mandibles in the different skeletal classes in the Saudi population.

Background: Assessing the relationship between the condyle and mandible volume and the various skeletal classes is essential in orthodontic diagnosis. The current study evaluated this relationship using volumetric cone-beam computed tomography (CBCT), cephalometric methods, and the correlations between them. Materials and Methods: The study examined 37 full-head CBCTs (74 condyles) from adults in the Saudi population. The condyle and mandible were separated from within the CBCT images. The volume of each segment was compared to measurements from multiple cephalometric analyses. Results: The combined total condylar volume has a moderate correlation with the maxillomandibular differential in each of the genders and in the total sample. Mandibular volume has a significant correlation with the Wits appraisal (sagittal classification) in males. It was also significantly correlated with the vertical classification using gonial angles in females and in the total sample. Conclusion: The relationship between mandible and condyle volume and cephalometric measurements is both dimensional and within the maxillomandibular complex rather than positional or related to the cranial base. Also, the correlation between the condylar and mandibular volumes and the sagittal and vertical dimensions in the orthodontic skeletal classes provides better insight into the mandibular complex.

The median lingual foramen in the era of orthognathic virtual surgical planning.

The median lingual foramen (MLF), which contains neurovascular bundles, is located in an area commonly considered safe for surgical procedures. However, published reports of severe complications after interventions in the mandibular symphysis area indicate the need for caution when approaching this region surgically. The aim of this study was to evaluate the vertical location of the MLF and the median lingual canal (MLC) by measuring the distances of these landmarks to the root apex of the lower central incisors (LCI) and to the menton cephalometric point (Me) on pre-orthognathic surgery cone beam computed tomography scans (N = 100). The results were analyzed in relation to the patients' type of deformity, age, sex, and number of foramina (single vs multiple). The median MLF-LCI and MLF-Me distances were 5.9 mm and 15.0 mm, respectively, while the mean MLC-LCI and MLC-Me distances were 9.7 mm and 11.6 mm, respectively. The mean LCI-Me distance was 21.3 mm, while the mean MLC length was 3.4 mm. Apart from the length of the MLC, the distances were all significantly greater in the male patients than in the female patients. The MLC-Me distance and MLC length differed significantly according to the number of foramina. In preoperative planning, the vertical locations of the MLF and respective MLC appear to be relevant for avoiding neurovascular complications.

Upper Airway Dimensions among Different Skeletal Malocclusions: A Retrospective Observational Study by Cephalometric Analysis.

The aim of the present work was to investigate the upper airway dimensions in adult non-orthodontic patients, equally divided according to their skeletal class. METHODS: In this retrospective cross-sectional study, lateral cephalometric radiographs of adult patients referred for orthodontic consultation were collected. Cephalometric tracing was performed with dedicated software. For each measure, descriptive statistics were calculated. Cephalometric measurements between the different skeletal classes were compared. Linear regressions were performed between upper airway diameters and cephalometric measurements, sex and age. Significance was predetermined for p < 0.05. RESULTS: Lateral cephalometric radiographs of 120 patients were reviewed. Nasopharynx length (NL) and depth (PD) measurements were significantly shorter in skeletal class III patients (p < 0.05). The superior pharyngeal airway space (SPAS) was found to be significantly shorter in class III patients as compared to class II patients (p < 0.05), and the mean airway space (MAS) of class I patients was found to be significantly shorter compared to class II patients (p < 0.05). Palate length (PL) values were found to be significantly longer in class I (p < 0.05). Linear regressions showed that the sella-nasion-A point angle (SNA) and Riedel's angle between point A, the nasion and point B (ANB) significantly influenced NL and PD (p < 0.05). CONCLUSIONS: Class III patients show significantly shorter nasopharynx measurements; clinicians should consider that this sagittal discrepancy could be related to an altered anatomy of the upper respiratory tract.

Nasal profile changes after orthodontic tooth extraction in Class II, Division 1 malocclusion patients: A retrospective study.

INTRODUCTION: This study aimed to investigate changes in the facial soft-tissue profile, especially the nose, following fixed orthodontic treatment, with or without tooth extraction, in individuals diagnosed with dental Class II malocclusion. MATERIALS AND METHODS: Cephalometric images of 81 individuals with dental Class II malocclusion who underwent fixed orthodontic treatment were assessed before and after treatment. The participants were categorized into three groups: non-extraction; upper first premolar extraction; and four first premolar extractions. The parameters measured were: upper lip height, upper lip to E-plane, lower lip to E-plane, lower lip height, nasolabial angle, nasomental angle, facial convexity, lower anterior face height, soft-tissue facial convexity, nasal tip angle, nasal bridge length, N'-nasal bridge point, nasal bone length, nasal bone angle, nasal depth, columella convexity, and nose height. RESULTS: Within the upper two extraction group, there were significant increases at the start and end periods in nasolabial angle (P = 0.023), nasal depth Pr to Ac (P = 0.027), and nasal depth Pr to N-Prn (P = 0.040); and decreases in columella convexity (P = 0.010), upper lip to E-plane (P = 0.009), and nasomental angle (P = 0.009). There were significant results in comparisons between measurements based on the extraction status in the mean nasolabial angle (P = 0.011), mean columella convexity (P = 0.028), and mean lower lip to E-plane (P = 0.045). CONCLUSION: Orthodontic treatment involving tooth extraction may potentially affect the nasolabial angle and nasal depth. During treatment planning, it is crucial to consider the potential changes that may occur to the nose and any alterations that may be needed to achieve the desired esthetic outcome.

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.

Gender differences in the upper airway, craniofacial morphological and polysomnographic parameters in patients with obstructive sleep apnoea.

BACKGROUND: Obstructive sleep apnoea (OSA) is a common sleep disorder characterized by repetitive episodes of upper airway collapse during sleep associated with arousals with or without oxygen desaturation. OBJECTIVE: This study aims to assess and analyse the morphological and neurological factors associated with obstructive sleep apnoea using polysomnography study data and two-dimensional cephalometric analysis of airway and skeletal parameters and their correlation in the patients with varying severities of obstructive sleep apnoea. METHODS: This study included 892 patients who underwent a complete work up, including a thorough history, clinical examination, standard polysomnography study and 2D cephalometric analysis to diagnose obstructive sleep apnoea. This study divided the participants into two groups based on the AHI score from the PSG study: AHI < 15 and AHI > 15 groups. The groups were further divided into male and female groups to study the prevalence of OSA. The analysis involved 13 cephalometric parameters: Seven linear and six angular measurements. The airway parameters measured in this study were minimum posterior airway space (PAS_min), hyoid bone to the mandibular plane (H_MNP) and soft palate length (SPL). All the subjects in this study underwent a standard overnight polysomnography study at the sleep centre in Samsung Medical Center. RESULTS: A total of 892 adult participants (M: F = 727:165, mean age: 50.6 ± 13.2 years and age range: 18-85 years). AHI >15 group was significantly older with higher BMI, NC and WC compared to the AHI < 15 groups in both male and female groups. There was statistical significance observed in N1, N3, AI, ODI, lowest saturation (%) and apnoea max length between the groups (p < .001). The arousal index (AI), especially the respiratory arousal index was considerably higher in the male group. There were significantly higher values in all the PSG parameters in the male group. In the airway parameters, hyoid bone position and soft palate length showed significant differences (p < .001), whereas the PAS did not show any differences (p = .225) between the AHI <15 and AHI >15 groups. The overall skeletal cephalometric parameters showed no significant differences between the groups, whereas the gonial angle and AB to mandibular plane angle showed significant differences in the female group (p = .028, p = .041 respectively). CONCLUSION: The partial correlation of cephalometric parameters with AHI showed a stronger correlation between the H_MNP and AHI in both men and women. The position of the hyoid bone and the soft palate length influences the progression of OSA, especially in male patients. This study found no direct association between the minimum PAS and varying severities of OSA in men and women. We speculate that more than the craniofacial morphological factors such as the sagittal and vertical position of the maxilla and the mandible, the position of the hyoid bone might be more responsible for the severity of OSA.