Establishment of the mid-sagittal reference plane for three-dimensional assessment of facial asymmetry: a systematic review : Establishment of the mid-sagittal reference plane: a systematic review.

OBJECTIVE: To systematically review the literature for mid-sagittal plane establishment approaches to identify the most effective method for constructing the mid-sagittal plane for the evaluation of facial asymmetry. MATERIALS AND METHODS: Six electronic databases (PubMed, Medline (via Ovid), EMBASE (via Ovid), Cochrane Library, Web of Science, and Scopus) and grey literature were searched for the studies that computed the mid-sagittal reference plane three-dimensionally, using a combination of MeSH terms and keywords. The methodological quality and the level of evidence for the included studies were analyzed using QUADAS-2 and GRADE, respectively. RESULTS: The preliminary search yielded 6746 records, of which 42 articles that met the predefined inclusion criteria were included in the final analysis. All the included articles reported the construction of the mid-sagittal reference plane (MSP) using varied methods. The risk of bias and concerns regarding the applicability of the included studies were judged to be 'low'. The level of evidence was determined to be 'low' for the effectiveness of the technique and 'moderate' for the ease of clinical applicability. CONCLUSION: Despite methodological heterogeneity, this review substantiates the comparable efficacy of cephalometric and morphometric MSP construction methods. A fully automated morphometric MSP holds promise as a viable option for routine clinical use. Nevertheless, future prospective studies with an emphasis on the impact, accuracy, and clinical applicability of MSP construction techniques in cases of facial asymmetry are required. CLINICAL RELEVANCE: The present review will assist clinicians in selecting the most suitable method for MSP construction, leading to improved treatment planning and ultimately more favorable treatment outcomes.

Skeletal, dentoalveolar and soft tissue changes after stabilization splint treatment for patients with temporomandibular joint disorders.

BACKGROUND: Temporomandibular disorder (TMD) is a grouping of heterogeneous disorders with multifactorial origins. Stabilization splints (SS) have demonstrated an acceptable treatment effect in TMD. The possible changes at the skeletal, dental, and soft tissue levels need to be addressed to evaluate the benefit/risk ratio of this therapeutic procedure. Accordingly, this study aimed to three­dimensionally evaluate skeletal, dentoalveolar and soft tissue changes after SS treatment for patients with TMD. METHODS: This retrospective study included 74 adult patients with myofascial and/or intra-articular disorders (25 males and 49 females), with an average age of 22.88 ± 4.8 years, who underwent SS treatment. Pre- and post-treatment Cone beam computed tomography were analysed using Invivo 6.0.3 software. The primary outcome was the vertical skeletal and dentoalveolar changes, while the secondary outcomes were the anteroposterior skeletal, dentoalveolar and soft tissue changes. Paired t-test and Wilcoxon rank sum test were used for statistical analyses. RESULTS: For the primary outcome; skeletally, there was a significant increase in mandibular plane inclination (difference: 0.82°±1.37), decrease facial height ratio (difference: 0.45%±1.07) and at the dentoalveolar level, the inclination of the functional (FOP-SN, FOP-FH) and bisecting (BOP-SN, BOP-FH) occlusal planes exhibited a significant increase too (difference: 0.38 ± 1.43°, 0.49 ± 1.62°, 0.44 ± 1.29° and 0.41 ± 1.17°, respectively) and also a decrease in the overbite (difference: -0.54 ± 0.83). For the secondary outcomes; there was a significant decrease in mandibular position (SNB) (difference: 1.60 ± 1.36°) and increase in the overjet (difference: 0.93 ± 1.04, p < 0.001) and a significant lower lip retrusion (difference: 0.33 ± 1.01 mm p < 0.01), was observed too. CONCLUSIONS: SS therapy resulted in significant vertical skeletal and dentoalveolar changes that were manifested mainly by facial height ratio, mandibular and occlusal plane changes, and to a lesser extent, significant anteroposterior skeletal, dentoalveolar, and soft tissue changes in the form of mandibular position, increased overjet and a more retrusive lower lip. These changes should be considered during patients' selection prior to initiating SS therapy.

Comparison of PAS and adenoids in patients with and without maxillary micrognathia before orthodontic treatment.

OBJECTIVE: Craniofacial anomalies are widely discussed as predisposing factors of breathing disorders. Since many more cofactors exist, this study investigated the association between maxillary micrognathia and morphological changes of posterior airway space and adenoids in these patients. MATERIAL AND METHODS: Cephalometric radiographs of n = 73 patients were used for data acquisition. The patients were divided into two groups according to certain skeletal characteristics: maxillary micrognathia (n = 34, 16 female, 18 male; mean age 10.55 ± 3.03 years; defined by a SNA angle < 79°) and maxillary eugnathia (n = 39, 19 female, 20 male; mean age 10.93 ± 3.26 years; defined by a SNA angle > 79°). The evaluation included established procedures for measurements of the maxilla, posterior airway space and adenoids. Statistics included Kolmogorov-Smirnov-, T- and Mann-Whitney-U-Tests for the radiographs. The level of significance was set at p < 0.05. RESULTS: The cephalometric analysis showed differences in the superior posterior face height and the depth of the posterior airway space at palatal level among the two groups. The depth of the posterior airway space at mandibular level was the same for both groups, just as the size of the area taken by adenoids in the nasopharynx. CONCLUSIONS: Skeletal anomalies affect the dimension of the posterior airway space. There were differences among the subjects with maxillary micrognathia and these with a normal maxilla. However, the maxilla was only assessed in the sagittal direction, not in the transverse. This study showed that the morphology of the maxilla relates to the posterior airway space whereas the adenoids seem not to be affected. CLINICAL RELEVANCE: Maxillary micrognathia is significantly associated with a smaller depth of the posterior airway space at the palatal level compared to patients with maxillary eugnathia.

Photographic analysis of orofacial soft tissue alterations related to rapid maxillary expansion in pediatric patients.

Maxillary transverse deficiency is widely recognized as one of the most common skeletal issues in orthodontics, and rapid maxillary expansion (RME) is commonly employed as a treatment method. This study aimed to investigate the impact of RME on the soft tissues of the orofacial region in pediatric patients. The study included two groups: an experimental group comprising 30 patients (16 females and 14 males) with maxillary skeletal transverse deficiency who required rapid maxillary expansion (RME), and a control group consisting of patients (10 females and 10 males) who did not require RME or orthodontic treatment. Frontal and profile photographs were taken before and after RME for both groups. Frontal photographs were used to obtain 12 linear measurements, while profile photographs were used to perform 2 linear and 2 angular measurements using the "protractor" and "pixel ruler" software. Burstone-Legan, Steiner and Rickett's analyses were performed to determine the locations of the upper and lower lips. Student t-test, paired samples t-test and Mann-Whitney U test were used to evaluate the data. In the experimental group, there was a statistically significant increase in nose width and intercommissural distance at the end of the treatment (p < 0.05). Similarly, both the experimental and control groups showed a statistically significant increase in the dorsum of nose length at T2 compared to the initial measurement (p < 0.05). Furthermore, the male participants in the experimental group exhibited a statistically significantly higher increase in nose length and dorsum of the nose during the T1 and T2 periods compared to the female participants in the experimental group (p < 0.05). RME may lead to changes in soft tissues in pediatric patients and was observed to be gender-specific. However, these changes were not clinically noticeable, and long-term follow-up studies are needed to determine the long-term effects of these changes.

Noninvasive conservative management of anterior open bite treated with TADs versus clear aligner therapy.

OBJECTIVES: Anterior open bite can be treated non-surgically via molar intrusion using temporary skeletal devices (TAD). Clear aligner therapy (CAT) is recognized as a viable therapeutic modality for non-extraction treatment of adults with mild open bite. This study aimed to compare the treatment effect and mechanisms of open bite closure between patients treated with braces and TADs double arch intrusion and those treated with CAT. Treatment success at T3 was based on 1- positive overbite on ceph; 2- Change in the vertical dimension 3- post treatment POSI score equal to zero. MATERIAL AND METHODS: The TAD group includes 18 consecutively treated patients from the main author. The CAT group consisted of 16 selected patients from three different orthodontists. The observation time points were as follows: pretreatment (T1), end of molar intrusion and positive overbite achieved (T2), end of treatment (T3), at least 6-month follow-up (T4). Treatment changes were assessed by cephalometric analysis and frontal intraoral photo. RESULTS: At the end of treatment, 100% of the patient of the TAD group and 78,6% of the CAT group had a posi score of 0. The TAD group showed a significant reduction in vertical measurements (SN-MPA: -1,55° ± 0.41, LAFH: -3,05 ± 0.51 mm, U6-PP: -1.48 ± 0.30 mm), but the CAT group did not have significant changes for these variables. Both groups had significant increases in overbite from T1 to T3 (TAD: 4,32 ± 0,5 mm; CAT: 2,33 ± 0.56 mm), and overbite remained stable at T4. The CAT group did not have a significant upper molar intrusion, but a significant extrusion of 1.22 ± 0.42 mm of the lower incisor occurred. CONCLUSION: The TAD group achieved bite closure by upper molar intrusion, lower molar and incisors vertical control, and mandibular plane counterclockwise rotation, resulting in an improved AP and vertical relationship. The CAT group achieved bite closure through the lower incisor extrusion without significant change in the vertical dimension. CLINICAL RELEVANCE: This study provides relevant information about the skeletal and dental changes of open bite treatment with TADs double arch intrusion. The comparison with a control group treated with CAT confirms known information.

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.

Do patients with different craniofacial patterns have differences in upper airway volume? A systematic review with network meta-analysis.

BACKGROUND: Craniofacial skeletal discrepancies have been associated with upper airway dimensions. OBJECTIVE: To identify differences in upper airway volume across different sagittal and vertical skeletal patterns. SEARCH METHODS: Unrestricted literature searches in eight databases/registers for human studies until May 2023. SELECTION CRITERIA: Cross-sectional studies measuring upper airway volumes using three-dimensional imaging in healthy patients of different sagittal (Class I, Class II, and Class III) or vertical (normodivergent, hypodivergent, and hyperdivergent) craniofacial morphology. DATA COLLECTION AND ANALYSIS: Duplicate independent study selection, data extraction, and risk of bias assessment. Random-effects frequentist network meta-analysis was performed followed by subgroup-analyses and assessment of the quality of clinical recommendations (confidence in effect estimates) with the CINeMA (Confidence in Network Meta-Analysis) approach. RESULTS: Seventy publications pertaining to 66 unique studies were included with 56 studies (5734 patients) contributing to meta-analyses. Statistically significant differences were found for total  pharyngeal airway volume, with Class II having decreased airway volume (-2256.06 mm3; 95% Confidence Interval [CI] -3201.61 to -1310.51 mm3) and Class III increased airway volume (1098.93 mm3; 95% CI 25.41 to 2172.45 mm3) compared to Class I. Significant airway volume reductions for Class II were localized mostly at the oropharynx, followed by the palatopharynx, and the glossopharynx. Significant airway volume increases for Class III were localized mostly at the oropharynx, followed by the intraoral cavity, and hypopharynx. Statistically significant differences according to vertical skeletal configuration were seen only for the oropharynx, where hyperdivergent patients had reduced volumes compared to normodivergent patients (-1716.77 mm3; 95% CI -3296.42 to -137.12 mm3). Airway differences for Class II and Class III configurations (compared to Class I) were more pronounced in adults than in children and the confidence for all estimates was very low according to CINeMA. CONCLUSIONS: Considerable differences in upper airway volume were found between sagittal and vertical skeletal configurations. However, results should be interpreted with caution due to the high risk of bias, owing to the retrospective study design, inconsistencies in anatomic compartment boundaries used, samples of mixed children-adult patients, and incomplete reporting. CLINICAL TRIAL REGISTRATION: PROSPERO (CRD42022366928).

Relationships of Sagittal Skeletal Discrepancy, Natural Head Position, and Craniocervical Posture in Pakistani Children.

OBJECTIVE: To assess the natural head position (NHP), mean sagittal skeletal discrepancy, and craniocervical posture in children presenting to tertiary care hospital. STUDY DESIGN: Observational study. Place and Duration of the Study: Department of Orthodontics, Karachi Medical and Dental College, Karachi, Pakistan, from January to April 2022. METHODOLOGY: A total of 121 participants, of either gender aged 11 to 15 years, were selected for this study. The mean age of the participants was 13.4 ± 1.2 years, and their average Frankfort mandibular plane angles (FH/ML) were recorded. Data collection took place following approval from the Ethics Review Board (ERB), and verbal informed consent was obtained from all participants. Cephalometric radiographs were taken in the natural head position (NHP) for all 121 participants. Based on their ANB angles, the participants were categorised into skeletal classes I, II, and III. The study assessed and compared variables such as head posture, craniocervical posture, and sagittal craniofacial morphology. RESULTS: The study included a sample of 121 children with a mean age of 13.4 ± 1.2 years. Among the participants, 58% were males, while 42% were females. Based on their ANB angles, participants were classified into skeletal classes I (n=44), II (n=73), and III (n=4). The correlation analysis between craniofacial posture, natural head position, and sagittal skeletal classes (I, II, and III) did not reveal any statistically significant results. Moreover, within each skeletal class, there were no significant differences observed in craniocervical posture between males and females when considering demographic variables. CONCLUSION: This study indicates that there is no discernible difference in the craniocervical posture of young Pakistani children aged 11 to 15 years, regardless of gender, in relation to skeletal relationships in classes I, II, and III. These findings suggest that sagittal skeletal discrepancies may not significantly impact craniocervical posture in this particular age group. KEY WORDS: Craniocervical posture, Sagittal discrepancy, Natural head position.

A retrospective study evaluating the influence of Class III correction appliances on the sagittal pharyngeal airway dimension.

The aim of this study was to compare the effects of Class III correction appliances including the Facemask (FM), and the new non-compliance fixed functional appliances such as the Reversed Forsus Fatigue Resistant Device (FRD), as well as the CS-2000 (CS), on the sagittal pharyngeal airway dimension (SPAD). Pre-treatment and post-treatment lateral cephalograms of 45 patients who underwent Class III appliance treatment, using either FM, Reversed FRD, or CS were collected from the files of treated patients. SPAD changes were evaluated in each group, and comparisons were conducted between the three study groups. Additionally, sagittal and vertical skeletal measurements were conducted. The FM, the Reversed FRD, and the CS, were found to generate a significant increase in the SPAD, with the Reversed FRD contributing to the most significant change at the OPAA (116.80 ± 26.36 mm2). All three appliances elicited significant antero-posterior changes in the SNA°, SNB°, and ANB°, also with the greatest intermaxillary change documented with the employment of the Reversed FRD (ANB° = 3.33 ± 0.82°). As for the vertical dimension, the FM, the Reversed FRD, and the CS elicited significant FMA° increases, with the greatest change attributed to the FM (FMA° = 2.32 ± 0.97°). Therefore, the three tested Class III corrective appliances generated significant SPAD, antero-posterior, and vertical changes. However, the Revered FRD showed a superior impact in increasing the SPAD at the OPAA level and in eliciting significant intermaxillary changes.

Three-dimensional modelling and morphometric analysis of skull of badger (Meles meles) with computed tomography images.

BACKGROUND: Morphometric measurements help to understand the skull morphology in different animal species, detect skull deformations and figure out their causes. OBJECTIVES: The aim of this study is to make a three-dimensional (3D) modelling of the badger skull using computed tomography, to show its anatomical structures and to reveal the morphometric measurement values. METHODS: Skull measurements were carried out using a digital calliper at 27 measurement points based on metric measurement points. After the scanned images were stored in Digital Imaging and Communications in Medicine format, they were transferred to MIMICS 20.1 (The Materialize Group) programme and 3D models the skulls were created. The surface area and volume values of the skulls were calculated on these models. RESULTS: The volume and surface area parameters were expressed as mean ± SE. Four different indices were calculated using osteometric measurements. Statistical analyses were made by determining the mean value and standard deviation of the examined properties and the correlation coefficients among these properties. In the metric measurement points taken as a basis, the longest measurement in the skulls was the total length and its mean value was 124.60 ± 0.64 mm. The shortest measurement was the breadth dorsal to the external auditory meatus, and its mean value was 6.75 ± 0.24 mm. CONCLUSIONS: Consequently, statistical differences in the craniometric values of badgers' skulls were determined by using CT and 3D modelling software. In addition, it was concluded that the badger skull can be easily distinguished from other carnivore species by carrying out morphometric measurements.

Validation of a fully automatic three-dimensional assessment of orthognathic surgery.

The aim of the present study was to propose and validate FAST3D: a fully automatic three-dimensional (3D) assessment of the surgical accuracy and the long-term skeletal stability of orthognathic surgery. To validate FAST3D, the agreement between FAST3D and a validated state-of-the-art semi-automatic method was calculated by intra-class correlation coefficients (ICC) at a 95 % confidence interval. A one-sided hypothesis test was performed to evaluate whether the absolute discrepancy between the measurements produced by the two methods was statistically significantly below a clinically relevant error margin of 0.5 mm. Ten subjects (six male, four female; mean age 24.4 years), class II and III, who underwent a combined three-piece Le Fort I osteotomy, bilateral sagittal split osteotomy and genioplasty, were included in the validation study. The agreement between the two methods was excellent for all measurements, ICC range (0.85-1.00), and fair for the rotational stability of the chin, ICC = 0.54. The absolute discrepancy for all measurements was statistically significantly lower than the clinical relevant error margin (p < 0.008). Within the limitations of the present validation study, FAST3D demonstrated to be reliable and may be adopted whenever appropriate in order to reduce the work load of the medical staff.

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.

The effect of tongue reduction for preventing adverse effects in patients undergoing class III orthognathic surgery: a three-dimensional comparative analysis.

OBJECTIVES: This study aims to evaluate the potential benefits of combining tongue reduction with mandibular setback surgery in patients undergoing class III orthognathic surgery. Specifically, we investigated whether this combined approach reduced the risk of surgical relapse, condylar resorption, and airway space reduction by mitigating tongue pressure on the mandible. MATERIAL AND METHODS: The study retrospectively enrolled patients who had undergone bilateral sagittal split ramus osteotomy (BSSRO) with at least 5 mm of setback and met the criteria of a body mass index > 20 kg/m2 and tongue volume > 100 mm3. The study included 20 patients with 10 in the tongue reduction group (TR, n = 10) and 10 in the BSSRO only group (SO, n = 10). RESULTS: The volumetric changes of the total airway space were significantly different between the TR and SO groups (p = 0.028). However, no significant differences were observed in the condylar resorption and postoperative relapse between the groups (p = 0.927 and 0.913, respectively). The difference between the resorption of the anterior and posterior segments of the condyle was also statistically insignificant (p = 0.826). Postoperative counterclockwise rotation of the proximal segment only demonstrated a significant correlation with postoperative relapse (p = 0.048). CONCLUSIONS: The reduction in tongue volume demonstrated a preventive effect on the reduction of the airway space after mandibular setback, although it did not yield statistical significance concerning surgical relapse and condylar volume. The counterclockwise rotation of the proximal segment might be responsible for the forward displacement of the distal segment and postoperative relapse. However, the clinical implications of this finding should be interpreted with caution owing to the limited sample size CLINICAL RELEVANCE: Tongue reduction could potentially serve as a preventive measure in preserving the airway space and might be beneficial in mitigating the risk of obstructive sleep apnea in patients with class III deformity.

Three-dimensional measurements of symmetry for the mandibular ramus.

BACKGROUND: The study examines a sample of patients presenting for viscerocranial computer tomography that does not display any apparent signs of asymmetry, assesses the three-dimensional congruency of the mandibular ramus, and focuses on differences in age and gender. METHODS: This cross-sectional cohort study screened viscerocranial CT data of patients without deformation or developmental anomalies. Segmentations were obtained from the left and right sides and superimposed according to the best-fit alignment. Comparisons were made to evaluate three-dimensional congruency and compared between subgroups according to age and gender. RESULTS: Two hundred and sixty-eight patients were screened, and one hundred patients met the inclusion criteria. There were no statistical differences between the left and right sides of the mandibular ramus. Also, there were no differences between the subgroups. The overall root mean square was 0.75 ± 0.15 mm, and the mean absolute distance from the mean was 0.54 ± 0.10 mm. CONCLUSION: The mean difference was less than one millimetre, far below the two-millimetre distance described in the literature that defines relative symmetry. Our study population displays a high degree of three-dimensional congruency. Our findings help to understand that there is sufficient three-dimensional congruency of the mandibular ramus, thus contributing to facilitating CAD-CAM-based procedures based on symmetry for this specific anatomic structure.

Exploratory Study of Growth of Circumference of Mandibular Fossa Adjacent to Petrous Portion of Temporal Bone Using Dried Skulls.

The morphogenetic process of development of the circumference of the mandibular fossa during tooth eruption, which involves the replacement of deciduous teeth with permanent teeth, is strongly affected by occlusion. To the best of our knowledge, no studies have investigated the effect of occlusion on this process. This study investigated the morphogenetic process of development during tooth eruption using dried skulls harvested from Indian donors. The average distance between the ala-major-squamosa suture and the foramen ovale according to age group was as follows: 3.24 mm in the 8-month-old group and 8.92 mm in the adult group. The average distance between the ala-major-squamosa suture and the apex of the articular tubercle according to age groups was as follows: 10.38 mm in the 8-month-old group and 19.34 mm in the adult group. The average distance between the point of intersection of the petrosquamous fissure and petrotympanic fissure located on the perpendicular line drawn posteriorly from the shortest distance of the medio-lateral axis between the ala-major-squamosa suture and the apex of the articular tubercle according to age group was as follows: 9.68 mm in the 8-month-old group and 14.3 mm in the adult group. These results suggest that the mandibular fossa is strongly affected by load due to occlusion, unlike the growth of the neurocranium. This indicates that the effect of occlusion is a secondary element in the morphogenetic process of development of the circumference of the mandibular fossa.

[Mandibular osteotomy, a simpler and safer method of osteosynthesis]. / Ostéotomie mandibulaire, une méthode plus simple et plus sûre d'ostéosynthèse.

Bilateral sagittal split osteotomy (BSSO) is a surgical procedure to treat mandibular malpositions. However, this surgery is associated with a risk of recurrence. Osteosynthesis techniques may be the cause of early recurrences. This study aims to demonstrate the efficiency and stability of osteosynthesis with two bicortical screws placed with a transjugal approach. We included patients who benefited from a BSSO alone, between May 2020 and August 2021. We performed the osteosynthesis using two bicortical screws placed with a transjugal approach. All the patients underwent lateral X-rays before the surgery, one week after and minimum six months after the intervention. These medical images allowed to study the mandibular movements during the intervention and the osteosynthesis stability. Twenty-five patients benefited from a BSSO alone. Patients obtained a satisfactory occlusal result. The results showed good stability of the two fragments, after surgery, during the studied period (average follow up of 8 months). Two bicortical screws osteosynthesis placed with a transjugal approach is a simple, effective and stable method for osteosynthesis in case of BSSO.

Les ostéotomies sagittales bilatérales mandibulaires (OSBM) sont des procédures chirurgicales utilisées pour traiter les malpositions mandibulaires. Toutefois, cette chirurgie présente un risque de récidive. Les techniques d'ostéosynthèse pourraient être la cause de récidives précoces. Cette étude vise à démontrer l'efficacité et la stabilité de l'ostéosynthèse à l'aide de deux vis bicorticales placées par voie transjugale. Nous avons inclus les patients ayant bénéficié d'une OSBM seule, entre mai 2020 et août 2021. Nous avons réalisé les ostéosynthèses à l'aide de deux vis bicorticales placées par voie transjugale. Tous les patients ont réalisé des clichés radiologiques de profil avant l'intervention, une semaine après et minimum six mois après. Ces imageries ont permis d'étudier les mouvements mandibulaires durant l'intervention et la stabilité de l'ostéosynthèse. Vingt-cinq patients ont bénéficié d'une OSBM seule. Les patients ont obtenu un résultat occlusal satisfaisant. Les résultats ont montré une bonne stabilité des deux fragments après la chirurgie durant la période étudiée (en moyenne, recul de 8 mois). En conclusion, l'ostéosynthèse à l'aide de deux vis placées par voie transjugale est une méthode simple, efficace et stable d'ostéosynthèse d'OSBM.

Comparison of craniometric measurements of New Zealand rabbit (Oryctolagus cuniculus L.) using three-dimensional scanner with digital calliper measurements: A methodological study.

As technology has developed in recent years, the use of three-dimensional (3D) scanners and printers has become widespread in the medical field. However, since this field is new, all kinds of methodological and experimental related studies gain importance. This study aimed to identify the differences between the calliper measurements by determining the craniometric data on the models constructed by scanning the crania of New Zealand Rabbits (Oryctolagus cuniculus L.), preferred as experimental animals, with a three-dimensional scanner. Therefore, a total of 12 New Zealand rabbits including 6 females and 6 males were used. After the crania that comprised the study material were macerated, they were subjected to 3D scanning. After the scanning process was completed, they were craniometrically measured both on the scanned models and by using a digital calliper. Analysis of the craniometric data of the 3D scanner showed that there was a difference between sexes at the level of p < 0.05 in widest length between the external acoustic meatus (WLBEAM), skull width and Foramen magnum height (FMH) parameters and cranial index data, and at the level of p < 0.001 in the largest nasal width (LNW) parameter. A statistical difference was found between sexes in frontal length, WLBEAM, LNW and FMH parameters and cranial index values in craniometric data collected with the digital calliper (p < 0.05). Consequently, the data collected in this study were found to be close to each other in both methods, suggesting that the 3D scanner may be used in morphometric studies.

Three-dimensional computed tomography analysis of airway volume in growing class II patients treated with Frankel II appliance.

OBJECTIVE: The purpose of this retrospective study was to assess the airway volume changes associated with the use of Frankel appliance (FR II) in Class II malocclusion patients using three-dimensional cone beam computed tomography (3D CBCT) imaging. MATERIALS AND METHODS: The sample consisted of 31 Class II malocclusion patients (mean age 9.24 ± 1.93 years old, 17 males (54.8%) and 14 females (45.2%)) treated with FR II appliance by the same orthodontist for an average of 9 months ± 20 days. CBCT images were taken before and after treatment and upper airway volume changes were measured using Dolphin 3D software version11.0 (Dolphin Imaging, Chatsworth, CA) and statistically compared. RESULTS: Airway volume of nasal cavity, nasopharynx, oropharynx, hypopharynx and the total airway volume significantly increased after the use of FR II appliance. In addition, significant increase was reported in maxillary base, inter-molar, inter-premolar and inter-canine width. Significant increase in soft tissue thickness was only recorded opposite to CV2. CONCLUSION: The use of the FR II appliance in growing subjects with Class II malocclusion led to a significant increase in the upper airway volume in addition to the anticipated dental and skeletal transverse expansion effects.

Reliability of landmark identification for analysis of the temporomandibular joint in real-time MRI.

BACKGROUND: Real-time magnetic resonance imaging (rtMRI) is essential for diagnosing and comprehending temporomandibular joint (TMJ) movements. Current methods for tracking and analysis require manual landmark placement on each acquisition frame. Therefore, our study aimed to assess the inter- and intra-rater reliability of placing cephalometric landmarks in frames from a dynamic real-time TMJ MRI. MATERIAL AND METHODS: Four real-time MRIs of the right TMJ were taken during mandibular movement at ten frames per second. Seven dentists identified ten landmarks on two frames (intercuspal position-ICP-and maximum mouth opening-MMO) twice at a two-week interval, yielding 112 tracings. Six typical cephalometric measurements (angles and distances) were derived from these landmarks. The reliabilities of landmarks and measurements were evaluated using distance-based (dbICC), linear mixed effect model intraclass correlation (lmeICC), and standard ICC. RESULTS: The average inter-rater reliability for the landmarks stood at 0.92 (dbICC) and 0.93 (lmeICC). The intra-rater reliability scores were 0.97 and 0.98. Over 80% of the landmarks showed an ICC greater than 0.98 (inter-rater) and over 0.99 (intra-rater). The lowest landmark ICC was observed for the orbitale and the oblique ridge of the mandibular ramus. However, the cephalometric angle and distance measurements derived from these landmarks showed only moderate to good reliability, whereas the reliability in the frames with ICP was better than those with MMO. Measurements performed in the ICP frame were more reliable than measurements in the MMO frame. CONCLUSION: While dentists reliably localize isolated landmarks in real-time MRIs, the cephalometric measurements derived from them remain inconsistent. The better results in ICP than MMO are probably due to a more familiar jaw position. The higher error rate of the TMJ measurements in MMO could be associated with a lack of training in real-time MRI analysis in dentistry.

[Comparison of the virtual surgical planning position of maxilla and condyle with the postoperative real position in patients with mandibular protrusion].

OBJECTIVE: To compare the difference between virtual surgical planning (VSP) position and postoperative real position of maxilla and condyle, and to explore the degree of intraoperative realization of VSP after orthognathic surgery. METHODS: In this study, 36 patients with mandibular protrusion deformity from January 2022 to December 2022 were included. All the patients had been done bilateral sagittal split ramus osteotomy (SSRO) combined with Le Fort Ⅰ osteotomy under guidance of VSP. The VSP data (T0) and 1-week postoperative CT (T1) were collected, the 3D model of postoperative CT was established and segmented into upper and lower jaws in CCMF Plan software. At the same time, accor-ding to the morphology of palatal folds, the virtual design was registered with the postoperative model, and the unclear maxillary dentition in the postoperative model was replaced. Then the postoperative model was matched with VSP model by registration of upper skull anatomy that was not affected by the operation. The three-dimensional reference plane and coordinate system were established. Selecting anatomical landmarks and their connections of condyle and maxilla for the measurement, we compared the coordinate changes of marker points in three directions, and the angle changes between the line connecting the marker points and the reference plane to analyze the positional deviation and the angle deviation of the postoperative condyle and maxilla compared to VSP. RESULTS: The postoperative real position of the maxilla deviates from the VSP by nearly 1 mm in the horizontal and vertical directions, and the anteroposterior deviation was about 1.5 mm. In addition, most patients had a certain degree of counterclockwise rotation of the maxilla after surgery. Most of the bilateral condyle moved forward, outward and downward (the average distance deviation was 0.15 mm, 1.54 mm, 2.19 mm, respectively), and rotated forward, outward and upward (the average degree deviation was 4.32°, 1.02°, 0.86°, respectively) compared with the VSP. CONCLUSION: VSP can be mostly achieved by assistance of 3D printed occlusal plates, but there are certain deviations in the postoperative real position of maxilla and condyle compared with VSP, which may be related to the rotation axis of the mandible in the VSP. It is necessary to use patient personalized condylar rotation axis for VSP, and apply condylar positioning device to further improve surgical accuracy.