Basal and dentoalveolar transverse parameters in different sagittal and vertical malocclusions in adults: a comparative study.

OBJECTIVE: This study sought to three-dimensionally (3D) evaluate the maxillomandibular basal bone and dentoalveolar widths using cone-beam computed tomography (CBCT) scans in adult Chinese populations with different vertical and sagittal facial skeletal patterns whilst no apparent posterior dental crossbite. MATERIALS AND METHODS: The retrospective cross-sectional comparative study enrolled CBCT images of 259 adult patients (125 males and 134 females). The subjects were divided into the hyperdivergent(n = 82), hypodivergent(n = 88), and normodivergent(n = 89) groups based on the Jarabak ratio (S-GO/N-Me), which were further divided into three subgroups of skeletal Class I, II and III, based on both the ANB angle and AF-BF parameters. ANOVA was used to analyze the extracted data of the studied groups. The intra- and inter-observer reliability was analyzed using the intra-class correlation coefficient (ICC). RESULTS: In all three vertical facial skeletal patterns, the skeletal Class II had significantly smaller mandibular basal bone width compared to skeletal Class I and Class III, both at the first molar and first premolar levels. The skeletal Class III seemed to have smaller maxillary basal bone width compared to skeletal Class I and Class II malocclusions; however, a significant difference was found only in the normodivergent pattern. As for the dentoalveolar compensation, it was most notable that in the hypodivergent growth pattern, the skeletal Class II had significantly smaller maxillary dentoalveolar width compared to the Class I and Class III groups, both at the first molar and first premolar levels. CONCLUSIONS: Based on the sample in the present study, skeletal Class II has the narrowest mandibular basal bone regardless of the vertical facial skeletal pattern. CLINICAL RELEVANCE: For Chinese adults with no apparent transverse discrepancy, the maxillomandibular basal bone and dentoalveolar widths are revealed in specific categories based on different vertical and sagittal facial skeletal patterns. In diagnosis and treatment planning, particular attention should be paid to skeletal Class II for possibly existing mandibular narrowing.

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.

Evaluation of an objective staging system for assessment of cervical vertebral maturation.

BACKGROUND: The aim of this study was to evaluate an objective method for Cervical Vertebral Maturation (CVM) staging. METHODS: An initial sample of 647 Lateral Cephalometric Radiographs (LCR) were staged according to the CVM (Baccetti et al.) by 4 examiners. The final sample (n = 394) included LCR on which the staging of the 4 investigators matched. The objective staging was performed by a single operator. The sample was divided according to the maturational stages into pre-pubertal, pubertal and post-pubertal groups. Measurements were performed on the cervical vertebrae (C2, C3 and C4). The angle between posterior and superior borders for C3 and C4 was the Superior Wall Inclination Angle (SWIA). Concavity Depth (CD) for C2, C3 and C4, and Body Shape (BS) (ratio of width to height of C3 and C4). Measurements of the 3 groups were compared. RESULTS: Reliability of subjective staging was high (intra-observer reliability, 0.948; inter-observer reliability, 0.967). Good agreement was observed for the outcomes measured. Intra-observer reliability was good (0.918, 0.885 and 0.722 for CD, BS and SWIA, respectively). The same was for the inter-observer reliability results (0.902, 0.889 and 0.728 for CD, BS and SWIA, respectively). Significant differences were observed for mean values of SWIA and BS and median values of CD within maturational stage. Similar findings were observed when the outcomes were compared at different phases (P < 0.001). CONCLUSIONS: A standardized, objective staging system using linear, angular measurements and ratios was applied for the determination of cervical vertebral maturation.

The relationship between the dimensions of frontal air sinus and skeletal malocclusions: A systematic review and meta-analysis.

Objective: The goal of this systematic review and meta-analysis was to assess whether the dimensions of the frontal air sinus correlate with skeletal malocclusion. Study selection: PubMed, Scopus, Embase, and Google Scholar were searched for relevant studies published up to May 23, 2023. The review included observational and retrospective studies that compared the dimensions of the frontal air sinus between different skeletal malocclusions. The PECOS method was used in this study ("Population, Exposure, Comparator, Outcome, and Study design"). The search was done using the following English keywords: "frontal sinus" OR "lateral cephalometric" OR "malocclusion" AND "surface area". Results: Seven studies were included, which involved 1101 participants, of whom 403 were class I, 375 were class II, and 323 were class III. These studies had a moderate risk of bias. The surface area of the frontal sinus in class III was significantly larger than in class I (standardized difference in means (SDM) = -0.971; 95 % CI = -1.147- -0.796; P < 0.001) and in class II (SDM = -1.535; 95 % CI = -1.732- -1.337; P < 0.001). Conclusion: Class III malocclusion is associated with a larger surface area of the frontal sinus compared to classes I and II.

Recommendations for standard criteria for the positional and morphological evaluation of temporomandibular joint osseous structures using cone-beam CT: a systematic review.

OBJECTIVE: This systematic review aimed to appraise the reliability and comprehensiveness of imaging methods in studies that used three-dimensional assessment of the temporomandibular joint (TMJ) in order to propose a standardized imaging method. METHODS: Six databases/search engines were searched up until September 2022. The outcomes of interest included measurements of the mandibular condyle, glenoid fossa, joint spaces, or the entire TMJ. Two checklists were utilized: one to assess the risk of bias, with a maximum score of 37, and the other, a pre-designed checklist consisting of 22 items to evaluate the comprehensiveness of the methods used, with a maximum score of 33. RESULTS: Out of the 2567 records retrieved, only 14 studies, which used cone bean computed tomography (CBCT), were deemed eligible and thus included in the qualitative analysis. Three studies were deemed of low risk of bias, while the remaining studies were rated as moderate to high risk of bias, primarily due to improper reporting of inter-observer agreement, varying reliability values, and a limited number of cases included in the reliability analysis. Regarding the comprehensiveness of the methods used, only four studies achieved relatively high scores. The deficiencies observed were related to the reporting of variables such as slice thickness and voxel size, absence of or improper reporting of intra- and inter-examiner reliability analyses, and failure to assess all osseous components of the TMJ. CONCLUSION: CBCT-based methods used to assess the positions and morphology of TMJ bony structures appear to be imperfect and lacking in comprehensiveness. Hence, criteria for a standardized assessment method of these TMJ structures are proposed. CLINICAL RELEVANCE STATEMENT: Accurately, comprehensively, and reliably assessing the osseous structures of the temporomandibular joint will provide valid and valuable diagnostic features of the normal temporomandibular joint, and help establish potential associations between these osseous features and temporomandibular disorders. REGISTRATION: The protocol for this systematic review was registered at the International Prospective Register of Systematic Reviews (PROSPERO, No.: CRD42020199792). KEY POINTS: •Although many methods have been introduced to assess the osseous structure of the temporomandibular joint, they yielded inconsistent findings. •None of the published studies comprehensively assessed the temporomandibular joint. •Recommendations for a comprehensive temporomandibular joint osseous assessment method were suggested for better validity and reliability of future research.

Three-dimensional evaluation of upper pharyngeal airway, hyoid bone, and craniocervical changes following stabilization splint therapy in adult patients with temporomandibular joint disorders and mandibular deviation: A retrospective study.

OBJECTIVE: This study aimed primarily to analyze the three-dimensional (3D) changes in the pharyngeal airway (PA), and secondarily, the hyoid bone (HB) and the craniocervical (CC) following stabilization splint (SS) therapy in adult patients with temporomandibular joint disorders (TMD) and mandibular deviation (MD). METHODS: Thirty-five adult patients with TMD and MD, who were treated using SS with a mean age of 25.14 ± 6.11 years, were enrolled in this retrospective clinical study. Pre- and post-therapeutic cone-beam computed tomography (CBCT) scans were analyzed. PA dimension,nasopharyngeal, oropharyngeal, hypopharyngeal, sub-hypopharyngeal, and total pharyngeal airway spaces were measured in surface area, volume, minimum constricted area (MCA) and width, HB position, and CC posture were analyzed three-dimensionally using InVivo 6.0.3 and Dolphin 11.95 software. Wilcoxon rank-sum or Paired t-test was conducted, and P < 0.05 was considered significant. RESULTS: SS therapy was administered for a period of 9.49 ± 4.02 months. The oropharyngeal airway space showed a significant decrease in sagittal width. The hypopharyngeal surface area, volume, MCA, and sagittal width decreased significantly. In terms of HB, hyoid-mandibular plane (H-MP), retrognathia-third vertebra's most inferior-anterior (RGN-C3ia), and retrognathia-Sella (RGN-S) distances significantly decreased. The Nasion-Sella line and the line that passes through C2ip to the odontoid process posterior tangent (NSL-OPT) angle in CC posture also decreased significantly. CONCLUSION: SS therapy in TMD patients with MD mainly results in narrowing of the hypopharyngeal region, no change in HB position and improvement in head posture. These results undoubtedly assist in diagnosis and treatment of clinical conditions.

Dimensional and positional temporomandibular joint osseous characteristics in normodivergent facial patterns with and without temporomandibular disorders.

OBJECTIVE: This study evaluated the dimensional and positional osseous temporomandibular joint features in normodivergent facial patterns with and without temporomandibular disorders. METHODS: A total of 165 adult patients were divided into two groups: group 1 (n = 79 patients; 158 joints): temporomandibular disorders patients and group 2 (n = 86 patients; 172 joints): non-temporomandibular disorders patients. Three-dimensional positional and dimensional temporomandibular joint characteristics, including glenoid fossa, mandibular condyles, and joint spaces, were assessed by cone beam computed tomography. RESULTS: The glenoid fossa positions in the three orthogonal planes and height showed statistical significance between the two studied groups. The temporomandibular disorders patients showed higher horizontal and vertical condyle inclinations while anteroposterior inclination was less, and the condyle was positioned more superior, anterior, and lateral in the glenoid fossa. The condyle width and length showed no significance between the two groups, while condyle height was smaller in temporomandibular disorders patients. Anterior and medial joint spaces increased while the superior and posterior joint spaces reduced in temporomandibular disorders patients. CONCLUSION: There were significant differences between the patients with and without temporomandibular joint disorders in terms of mandibular fossa positions and height as well as condylar positions and inclinations in horizontal and vertical planes together with reduced condylar height and reduced posterior and superior joint spaces in the temporomandibular disorders patients. CLINICAL RELEVANCE: The temporomandibular disorder is a multifactorial disorder in which one of these factors is the dimensional and positional characteristics of the temporomandibular joints; including or excluding this factor requires a comprehensive three-dimensional investigation of patients with TMD compared to the normal group under the condition that the facial pattern is average as a confounding factor.

Alveolar bone changes following bi-maxillary vertical molars' movements using clear aligners.

OBJECTIVE: This study aimed to assess the alveolar bone changes following maxillary and mandibular molars' intrusion and extrusion movements using Clear Aligners using Cone-Beam Computed Tomography (CBCT). MATERIALS AND METHODS: This is a retrospective clinical study in which 24 adult patients with pre-designed selection criteria and a mean age of 31.1 + 9.9 years were enrolled. The alveolar bone changes around one hundred thirty-three maxillary and mandibular molars intruded or extruded by Clear Aligners therapy were analyzed from CBCT using Invivo 6.0 software. Intra- and inter-examiner reliability analysis was performed using the intra-class correlation coefficient (ICC) and Cronbach's Alpha statistics. The paired t-test was used to analyze significant differences before and after treatment (T0-T1). The significance level was considered at P < 0.05. RESULT: The patients were divided into two groups: extrusion (48.9%, n = 65 molars' root) and intrusion (51.1%, n = 68 molars' root) group. There was a significant decrease in the alveolar bone changes in the buccal surface of the mandibular right and left 1st molars in the extrusion group (-1.05 ± 0.97, -0.76 ± 1.12 mm, respectively) and the maxillary left 2nd molars in intrusion group (-0.42 ± 0.77 mm), and the lingual surface of intrusion of the mandibular left 1st molar (-0.64 ± 0.76 mm). Comparing the mean maxillary and mandibular changes (T0-T1) of both studied groups showed that the buccal alveolar bone changes for the left 1st and right 2nd molars showed a significant difference in extrusion and intrusion groups, respectively. CONCLUSIONS: The buccal alveolar bone changes is considered the most affected surface following maxillary and mandibular molars' intrusion and extrusion movements using clear aligners, with mandibular molars being more affected than the maxillary ones.

Three-dimensional relationship between the degree of bilateral impacted mandibular third molars angulation and the mandibular dental arch parameters: a cross-sectional comparative study.

OBJECTIVE: The purpose of this study was to three-dimensionally evaluate the relationship between the degree of bilateral impacted mandibular third molar (IM3M) angulation and the mandibular dental arch parameters in normal skeletal and dental malocclusion patients. MATERIALS AND METHODS: In this retrospective cross-sectional comparative study, 120 adult subjects' cone-beam computed tomography (CBCT) images were three-dimensionally analyzed. The sample included 120 adults aged 20-30 years, with a gender distribution of 51 male and 69 female participants. The sample was divided into 100 adults with bilateral IM3M (study group) and 20 adults with normal bilateral erupted M3M (control group). The study group was sub-divided into three groups according to the degree of IM3M buccolingual angulation (BL°): group A, < 12° on the center of the ridge (N = 30), group B, 12-24° off-center of the ridge (N = 40), group C, > 24° off-center of the ridge (N = 30). The study group was also sub-divided into two groups according to IM3M mesiodistal angulation (MD°): group 1 from 10 to 45° (N = 36), group 2 > 45° (N = 64). Comparison within and between groups was performed using one-way ANOVA followed by Tukey's post hoc test. The correlation between IM3M, BL, and MD angulation and the mandibular arch parameter was calculated using Pearson's correlation coefficient. RESULTS: Statistically significant differences (P < 0.001) were found between the IM3M BL° and anterior teeth inclination, arch length (AL), and inter-second molar width (inter 2nd MW) as well as between the IM3M MD° with anterior crowding and the arch length (P < 0.001). A significant positive correlation was found between IM3M BL° and anterior teeth inclination and between IM3M MD° and anterior teeth crowding and inter 2nd MW. A significant negative correlation was observed between IM3M BL° and inter 1st MW and 2nd MW. CONCLUSION: The degree of buccolingual and mesiodistal angulation of the impacted mandibular third molars was related with mandibular dentoalveolar changes. Increased buccolingual angulation is generally associated with increased anterior teeth inclination and decreased 1st and 2nd inter-molar width. The increase in mesiodistal angulations was generally related with increased anterior teeth crowding and 2nd inter-molar width. CLINICAL RELEVANCE: Assessment of the relationship between the impacted mandibular third molars and the degree of arch discrepancy, and the position of mandibular incisors in the three planes of space might help in the decision-making process for the extraction of the impacted third molars in adult patients.

Effect of the vertical facial pattern on the developmental relationship between the nasal bone and maxillary central incisors.

BACKGROUND: This study aimed to investigate the effect of vertical facial patterns on the developmental relationship between the nasal bone and maxillary central incisors. METHODS: In this retrospective comparative study, the lateral cephalograms of 213 subjects (51 Males, 162 Females) with skeletal Class I malocclusion (aged 18-32 years) were classified into three equal groups: (1) hyperdivergent, (2) normodivergent, and (3) hypodivergent facial patterns based on the mandibular plane inclination (S-N/Go-Me). Several sets of measurements were extracted: (1) gradient and length of the nasal bone and maxillary central incisor, (2) the distance from apex and root of the nasal bone, and (3) maxillary central incisor to the true perpendicular from the digitized lateral cephalograms. The significance level was considered at P < 0.05. RESULTS: The inclination angle and length between nasal bone and maxillary central incisor were positively correlated independent of vertical facial type. The inclination angle of the nasal bone in the hypodivergent group was significantly larger than the other two vertical facial patterns. The inclination angle of the maxillary central incisor increased successively in the hyperdivergent, normodivergent, and hypodivergent groups. The length of the nasal bone in the hyperdivergent group was significantly longer than that in the hypodivergent and normodivergent groups. The maxillary central incisor length in the hyperdivergent group was significantly longer than in the hypodivergent group. CONCLUSION: A correlation between nasal bone and maxillary central incisors during the growth and development of the maxillofacial region was found. In Class I malocclusion subjects, hypodivergent patients were more likely to have a prominent and relatively short nasal bone and maxillary central incisors and vice versa.

Quantitative and qualitative condylar changes following stabilization splint therapy in patients with temporomandibular joint disorders.

OBJECTIVE: This study aimed to explore the quantitative and qualitative condylar changes following stabilization splint (S.S) therapy, including condylar position, morphology, and bone mineral density (BMD) in subjects with temporomandibular disorders (TMD). MATERIALS AND METHODS: In this retrospective clinical study, we enrolled 40 TMD subjects (80 joints) aged 18 to 35 years, for whom a S.S was used to treat TMD. The 80 TMD consists of 32 masticatory muscle disorders (myalgia) and 48 TMJ disorders (arthralgia). Cone beam computed tomography (CBCT) was used to scan the TMJs of subjects pre- and post-treatment for three-dimensional analysis (3D). Using Mimics software v.21.0, quantitative (3D condylar and joint spaces dimensions parameters were measured using linear measurements in millimeters, according to the Kamelchuk method and Ikeda method, while the assessment of anteroposterior condyle position within the glenoid fossa was based on the method of Pullinger and Hollender), and qualitative (a round bone tissue with an area of 2 mm2 in three representative areas according to the Kamelchuk method to measure condylar BMD) pre- and post-treatment. Intra- and inter-group statistical comparisons were performed using the Wilcoxon signed ranks and the Kruskal-Wallis test, respectively. RESULTS: The course of treatment was 6-12 months, with an average of 9.1 months. For the pre- and post-treatment quantitative comparisons, there was a statistically significant difference in the anterior joint space (AJS) and coronal medial space, as well as the condyle length in the myalgia group and condylar width in the arthralgia group. For qualitative measurements, a significant difference was observed in the posterior slope of the myalgia group and the arthralgia group's anterior, superior, and posterior slopes. The inter-group comparisons revealed significant differences in AJS, condylar length, and anterior slope density. CONCLUSION: In short-term follow-up, the S.S influenced patients with TMD from different origins; it changes anterior and coronal medial joint space, condyle length in myalgia, and width in arthralgia. Furthermore, it improved the condyle bone density more evidently in arthralgia. CLINICAL RELEVANCE: This study highlights the influence of S.S on symptomatic populations with TMD of different origins from a qualitative and quantitative perspective.

Three-dimensional phenotype characteristics of skeletal class III malocclusion in adult Chinese: a principal component analysis-based cluster analysis.

BACKGROUND: Skeletal class III malocclusion has a diverse and complicated aetiology involving environmental and genetic factors. It is critical to correctly classify and define this malocclusion to be diagnosed and treated on a clinically sound basis. Thus, this study aimed to provide reliable and detailed measurements in a large ethnically homogeneous sample of Chinese adults to generate an adequate phenotypic clustering model to identify and describe the skeletal variation present in skeletal class III malocclusion. MATERIALS AND METHODS: This is a retrospective cross-sectional study in which 500 pre-treatments cone-beam computed tomography (CBCT) scans of patients with skeletal class III malocclusion (250 males and 250 females) were selected following specific selection criteria. Seventy-six linear, angular, and ratios measurements were three-dimensionally analysed using InVivo 6.0.3 software. These measurements were categorised into 47 skeletal, 18 dentoalveolar, and 11 soft tissue variables. Multivariate reduction methods: principal component analyses and cluster analyses were used to present the most common phenotypic groupings of skeletal class III malocclusion in Han ethnic group of Chinese adults. RESULTS: The principal component analysis revealed eight principal components accounted for 72.9% of the overall variation of the data produced from the seventy-six variables. The first four principal components accounted for 53.37% of the total variations. They explained the most variation in data and consisted mainly of anteroposterior and vertical skeletal relationships. The cluster analysis identified four phenotypes of skeletal class III malocclusion: C1, 34%; C2, 11.4%; C3, 26.4%; and C4, 28.2%. CONCLUSION: Based on three-dimensional analyses, four skeletal class III malocclusion distinct phenotypic variations were defined in a large sample of the adult Chinese population, showing the occurrence of phenotypic variation between identified clusters in the same ethnic group. These findings might serve as a foundation for accurate diagnosis and treatment planning of each cluster and future genetic studies to determine the causative gene(s) of each cluster.

Comparison of three-dimensional maxillary growth across spheno-occipital synchondrosis maturation stages.

BACKGROUND: This study aimed to three-dimensionally compare the maxillary growth among the spheno-occipital synchondrosis (SOS) maturation stages in both genders. METHODS: This is a cross-sectional study of a retrospective type in which cone-beam computed tomography (CBCT) images of 500 patients aged 6 to 25 years (226 males and 274 females) were analyzed. The SOS was evaluated using the four-stage scoring system; completely open, partially fused, semi-fused, or completely fused. The SOS scoring and three-dimensional cephalometric measurements were analyzed by Invivo 6.0.3 software. Descriptive and analytical statistics were performed and a P-value < 0.05 was considered statistically significant. RESULTS: There was a statistically significant difference in maxillary measurements among SOS maturation stages in both genders (P < 0.05). The mean differences in the maxillary growth among the SOS maturation stages between SOS stages 2 and 3 were higher than those between stages 1and 2 and stages 3 and 4 for maxillary length and height in both genders. However, the mean difference in the maxillary width was higher between SOS stages 1 and 2 than those stages 2 and 3 and stages 3 and 4. On other hand, there may be lesser maxillary growth between SOS stages 3 and 4 for maxillary width, length (in males), and height. The growth curves showed high active growth of the maxilla as the SOS was still fusing (especially stage 2 and 3) than those of the fused (stage 4). Moreover, the acceleration of growth occurred earlier in females than males regarding chronological age but not for SOS maturation stages. CONCLUSIONS: The SOS maturation stages are valid and reliable maxillary skeletal maturation indicators for three-dimensional maxillary growth in both genders.

Three dimensional evaluation of the skeletal and temporomandibular joint changes following stabilization splint therapy in patients with temporomandibular joint disorders and mandibular deviation: a retrospective study.

BACKGROUND: Three-dimensional (3D) detailed evaluations of the mandibular mediolateral position, mandibular condylar position, and temporomandibular joint (TMJ) spaces following stabilization splints (SS) therapy in patients with temporomandibular joint disorders (TMD) and mandibular deviation (MD) have not been reported in the available literature. Accordingly, this study aimed to three-dimensionally analyze the skeletal and bony temporomandibular joint changes following stabilization splint therapy in adult patients with temporomandibular joint disorders and mandibular deviation. METHODS: This study is a retrospective clinical study that enrolled 26 adult patients with TMD and MD with a mean age of 24.86 years. The Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) was used to diagnose TMD. SS was adjusted weekly until occlusal contact stabilization occurred, and then adjusted monthly, patients were instructed to wear it at night for at least 10 h. The SS was removed after the elimination of TMD symptoms (TMJ/muscle pain on palpation, muscle spasm, and clicking) and having both condyles completely seated in a musculoskeletally stable position. Pre- and post-therapeutic Cone Beam Computed Tomography (CBCT) was analyzed. Mandibular mediolateral position, TMJ spaces, and mandibular condyle position were analyzed three-dimensionally using Mimics 21.0 software. Paired t-test or Wilcoxon rank-sum test was performed, and the significance level was considered at P < 0.05. RESULTS: The treatment period with SS therapy was 10.07 ± 3.1 months. The deviated chin was improved in 69.23% of the sample; the range of improvement was > 0 mm ≤ 3.9 mm. The mandibular rotation was significantly decreased from 3.58 ± 2.02° to 3.17 ± 1.60. The deviated side's superior and posterior joint TMJ spaces were significantly increased from 2.49 ± 0.88 mm and 1.25 ± 0.79 mm to 2.98 ± 1.02 mm and 1.86 ± 0.72 mm, respectively. The value of the difference from the bilateral condyle head position to the X and Z axes significantly decreased from 2.50 ± 1.56 mm and 2.30 ± 1.57 mm to 1.64 ± 1.58 mm and 1.82 ± 1.11 mm, respectively. CONCLUSION: The main positional effect of the stabilization splint treatment in TMD patients with MD includes considerable correction of mandibular deviation, improving facial asymmetry, and moving the condyle into a stable condylar position; these were done by promoting the mandible to rotate around the Z (roll) and Y (yaw) axes and by forward, downward, and outward condylar movement on the deviated side, respectively.

Correlation between the three-dimensional maxillomandibular complex parameters and pharyngeal airway dimensions in different sagittal and vertical malocclusions.

OBJECTIVES: This study aimed to determine the three-dimensional (3D) correlation between maxillomandibular complex parameters and pharyngeal airway dimensions in different sagittal and vertical malocclusions. METHODS: This retrospective cross-sectional study included the CBCT scans of 368 patients with a mean age of 23.81 ± 3.01 years. The patients were classified into three groups (skeletal Class I, II, and III). Each class group was divided into three subgroups based on vertical growth patterns (hypo-, normo-, and hyperdivergent). The maxillomandibular complex was evaluated in the three planes using 16 skeletal measurements. Naso-, oro-, hypo-, and total pharyngeal airway spaces were assessed in terms of width, volume, surface area, and minimum constricted area (MCA). Two-way ANOVA followed by the Bonferroni post-hoc test were used. RESULTS: The nasopharyngeal airway space was significantly lowest regarding sagittal and lateral widths in the skeletal Class III patients, the lowest volume and surface area were in hyperdivergent patients, and MCA was the highest in Class II and hypodivergent patients. The oro- and hypopharyngeal sagittal width, volume, surface area, and MCA were the lowest in the hyperdivergent patients, and oropharyngeal lateral width and hypopharyngeal sagittal width were the highest in skeletal Class III. The total pharyngeal volume, surface area, and MCA were the lowest in the hyperdivergent patients, and skeletal Class II patients had the lowest MCA. CONCLUSIONS: The pharyngeal airway dimensions differ with various sagittal and vertical malocclusions. These differences could apply to diagnosis, treatment planning, and possible changes following orthodontic/orthopedic or surgical treatment.

The dimensional and morphological assessment of frontal air sinus in different ages, genders and ethnicities (Arabian-Caucasian and Han-Chinese sub-populations).

OBJECTIVE: This study aimed to assess the dimensional and morphological measurements of the frontal air sinuses in different ages and genders in the two ethnicities. MATERIALS AND METHODS: This retrospective study included 360 subjects (160 males and 200 females) of both ethnicities. Subjects were divided based on age and gender into four groups, including an equal number of both males and females, for each age and ethnic group. The frontal air sinus dimensions were measured utilizing lateral cephalometric radiographs and computed using Winceph version 9.0 software. The frontal air sinus dimensions were compared between age groups in both genders and between ethnicity using an independent sample t test. The relationship between the frontal air sinus dimensions and subjects' age was evaluated using Pearson's correlation coefficient. RESULT: The frontal air sinuses measurements were larger in males than females in both ethnicities, except for the frontal sinus index, which was found to be larger in females than males. The frontal air sinus surface area and height showed statistically significant differences between the two age groups in both ethnicities (P < 0.05). The Arabian-Caucasian patients had a larger frontal sinus surface area, height, and depth than the Han-Chinese patients in both age groups. CONCLUSION: The size of the frontal air sinus increases with age; and continues to expand after the age of 20 years. Based on the Arabian-Caucasian and Han-Chinese sub-population findings, the frontal sinus is an effective tool for determining gender and appears to have potential in ethnicity identification.

Tridimensional Analysis of Incisive Canal and Upper Central Incisor Approximation.

OBJECTIVE: The present study aimed to estimate the location of the incisive canal (IC) concerning the upper central incisor roots (U1) in order to explore the amount of incisor retraction as per the envelope of discrepancy amongst Chinese patients with different vertical facial growth patterns. METHODS: This is a cross-sectional study that used a total of 207 pretreatment cone-beam computed tomography (CBCT) scans of adults with a skeletal class I relationship. Sixty-nine cases were included in each of the normodivergent, hypodivergent, and hyperdivergent facial groups. The IC volume was measured using Mimics 21 software. The IC width and IC-U1 proximity were measured using in vivo 6 software. Linear measurements were conducted at 3 vertical levels. RESULTS: The IC has shown a larger volume in the hyperdivergent group and male patients. Overall, the IC has recorded linear width greater than the inter-root distance of U1 in 59.1%, 66%, and 68.8% amongst the normodivergent, hypodivergent, and hyperdivergent facial groups, respectively, and in 58.3% of males and 70.8% of females. The overall sagittal distances between the U1 and IC were 4.00 ± 0.82 mm, 4.60 ± 0.83 mm, and 3.60 ± 0.80 mm amongst the normodivergent, hypodivergent, and hyperdivergent facial groups, respectively. CONCLUSIONS: The maximum sagittal distances between U1 and IC were 4.8 mm, 5.4 mm, and 4.4 mm amongst the normodivergent, hypodivergent, and hyperdivergent facial groups, respectively. Thereby, our findings have revised the retraction aspect of the envelope of discrepancy as per the different vertical facial growth patterns, which could serve a reference for the clinical practice involved considerable incisors movement, especially among Chinese patients.

Comparison of spheno-occipital synchondrosis maturation stages with three-dimensional assessment of mandibular growth.

BACKGROUND: This study aimed to compare spheno-occipital synchondrosis (SOS) maturation stages with a three-dimensional assessment of mandibular growth. METHODS: This is a cross-sectional study of a retrospective type, in which cone-beam computed tomography (CBCT) images of 500 patients aged 6 to 25 years (226 males and 274 females) were analyzed. The SOS was evaluated using the four-stage scoring system; completely open, partially fused, semi-fused, or completely fused. The SOS scoring and three-dimensional cephalometric measurements were analyzed by Invivo 6.0.3 software. Descriptive and analytical statistics were performed, and a P-value < 0.05 was considered statistically significant. RESULTS: There was a statistically significant difference in mandibular measurements among SOS maturation stages in both sexes (P < 0.05). The skeletal growth increments of mandibular variables across the SOS stages had higher mean differences between SOS stages 2 and 3 than those between stages 1 and 2 and stages 3 and 4 in both sexes. The mandibular growth curves increased with chronological age (earlier in females) and SOS maturation stages (mostly in stages 1, 2, and 3 than stage 4). CONCLUSIONS: The SOS maturation stages are valid and reliable mandibular skeletal indicators as evaluated with three-dimensional cephalometric mandibular measurements. The findings of growth increments and constructed growth curves of mandibular growth might be helpful in diagnosis and treatment planning.

Qualitative and quantitative three-dimensional evaluation of maxillary basal and dentoalveolar dimensions in patients with and without maxillary impacted canines.

BACKGROUND: This study aimed to three-dimensionally evaluate the qualitative and quantitative maxillary basal, dentoalveolar, and dental dimensions in patients with unilateral or bilateral maxillary impacted canines relative to their normal peers. MATERIALS AND METHODS: This is a retrospective comparative study. Cone-beam computed tomography images of one hundred and fifty adult patients were divided into three equal groups: unilateral, bilateral, and control groups. Each had 50 patients that were three-dimensionally analysed. The quantitative measurements involved three basal (molar basal width, premolar basal width, and arch depth), seven dentoalveolar (molar alveolar width, premolar alveolar width, inter-molar width, inter-premolar width, inter-canine width, arch length, and arch perimeter), and two dental (canine length and width) measurements. The qualitative measurements included four bone density areas (buccal, lingual, mesial, and distal) around the maxillary impacted canines. RESULT: Differences between the three groups were statistically different for the quantitative measurements involving the two basal variables (molar basal width and premolar basal width) and all measured dentoalveolar variables; these were smaller in the unilateral and bilateral groups compared with the control group (p < 0.001). Unilateral and bilateral impacted canine groups showed significantly wider and shorter canines than the control group (p < 0.001). The qualitative measurements (the four bone density areas) around unilateral and bilateral impacted canine groups showed significantly greater density than the control group (p < 0.001). There was no significant qualitative or quantitative difference between the unilateral and bilateral impacted canines. The three groups had no significant variations in terms of arch depth. CONCLUSION: Maxillary unilateral and bilateral canine impactions are associated with reduced basal and dentoalveolar dimensions as well as wider and shorter maxillary canines compared to normal peers. The quality of bone around unilateral and bilateral impacted maxillary canines is higher than in non-impacted cases. Unilateral and bilateral canine impactions have quite similar qualitative and quantitative parameters.

Orthodontic camouflage versus orthodontic-orthognathic surgical treatment in borderline class III malocclusion: a systematic review.

OBJECTIVE: This systematic review evaluated the available evidence regarding the skeletal, dentoalveolar, and soft tissue effects of orthodontic camouflage (OC) versus orthodontic-orthognathic surgical (OOS) treatment in borderline class III malocclusion patients. METHODS: Eligibility criteria. The included studies were clinical trials and/or follow-up observational studies (retrospective and prospective). Information sources. PubMed, Scopus, Science Direct, Web of Science, Cochrane, and LILACS were searched up to October 2021. Risk of bias. Downs and Black quality assessment checklist was used. Synthesis of results. The outcomes were the skeletal, dentoalveolar, and soft tissue changes obtained from pre- and post-cephalometric measurements. RESULTS: Included studies. Out of 2089 retrieved articles, 6 were eligible and thus included in the subsequent analyses. Their overall risk of bias was moderate. Outcome results. The results are presented as pre- and post-treatment values or mean changes in both groups. Two studies reported significant retrusion of the maxillary and mandibular bases in OC, in contrast to significant maxillary protrusion and mandibular retrusion with increased ANB angle in OOS. Regarding the vertical jaw relation, one study reported a significant decrease in mandibular plane inclination in OC and a significant increase in OOS. Most of the included studies reported a significant proclination in the maxillary incisors in both groups. Three studies reported a significant proclination of the mandibular incisors in OOS, while four studies reported retroclination in OC. CONCLUSION: Interpretation. The OSS has a protrusive effect on the maxillary base, retrusive effect on the mandibular base, and thus improvement in the sagittal relationship accompanied with a clockwise rotational effect on the mandibular plane. The OC has more proclination effect on the maxillary incisors and retroclination effect on the mandibular incisors compared to OOS. Limitation. Meta-analysis was not possible due to considerable variations among the included studies. Owing to the fact that some important data in the included studies were missing, conducting further studies with more standardized methodologies is highly urgent. Registration. The protocol for this systematic review was registered at the International Prospective Register of Systematic Reviews (PROSPERO, No.: CRD42020199591). CLINICAL RELEVANCE: The common features including skeletal, dental, and soft tissue characteristics of borderline class III malocclusion cases make it more difficult to select the most appropriate treatment modality that can be either OC or OOS. The availability of high-level evidence-systematic reviews-makes the clinical decision much more clear and based on scientific basis rather than personal preference.