OBJECTIVETo identify the morphological characteristics of craniofacial structure in patients with skeletal class III malocclusions.

METHODSThe study samples consisted of 63 lateral cephalometric radiographs of adult with class I malocclusion (32 male and 31 female, ages >17 years) and 27 patients with skeletal class III malocclusion (14 male and 13 female, ages >17 years, ANB >-3). The proportion of posterior cranial base and the mandibular length were measured.

RESULTThere was an increase in total mandibular length (Go-Gn, Cd-Gn) in female patients with class III malocclusion. There was a decrease in the posterior cranial base length (S-Ar) and an increase in mandibular length (Go-Gn) in male patients with class III malocclusion.

CONCLUSIONThe major craniofacial characteristics of skeletal class III malocclusion compared with those of class I malocclusion are smaller posterior cranial base in males and larger mandibular length in both sexes.

Adolescent ; Adult ; Cephalometry ; Facial Bones ; diagnostic imaging ; pathology ; Female ; Humans ; Male ; Malocclusion, Angle Class I ; diagnostic imaging ; pathology ; Malocclusion, Angle Class III ; diagnostic imaging ; pathology ; Radiography ; Skull ; diagnostic imaging ; pathology

To investigate three-dimensional morphological features of temporomandibular joint in skeletal malocclusion Class III with different vertical skeletal facial types.
 Methods: A total of 46 adults with skeletal malocclusion Class III were enrolled and allocated into a normal-angle, a high-angle and a low-angle groups. All patients were undergone cone beam computed tomography (CBCT). Images of temporomandibular joint were reconstructed and analyzed by Invivo 5. Nine measurements relevant to the positions and forms of condyle as well as joint spaces were performed.
 Results: Significant differences were not observed between the 2 sides of each group among skeletal malocclusion Class III (P>0.05). Compared with the high-angle and normal-angle patients, the low-angle patients had larger superior spaces, bigger gradients of the articular tublecle, longer condyle, and larger internal spaces between the condyle and the fossa. Compared with the low-angle and normal-angle patients, the high-angle patients had smaller condylar antero-posterior diameters.
 Conclusion: Class III malocclusion patients with different vertical skeletal patterns have different positions and forms of condyles, which should be paid attention to in clinic.
Adult ; Cone-Beam Computed Tomography ; Face ; diagnostic imaging ; Humans ; Image Processing, Computer-Assisted ; Malocclusion, Angle Class III ; diagnostic imaging ; Mandibular Condyle ; diagnostic imaging ; Temporomandibular Joint ; diagnostic imaging

OBJECTIVE: To assess three-dimensional (3D) changes of circummaxillary sutures following maxillary protraction with alternate rapid palatal expansions and constrictions (RPE/C) facemask protocol in maxillary retrusive children, and to investigate the relationship between the changes of circum-maxillary sutures and zygomaticomaxillary suture (ZMS) maturation, and to explore the factors of maxilla forward movement with RPE/C and facemask. METHODS: In the study (clinical trial registration No: ChiCTR2000034909), 36 maxillary retrusive patients were recruited and block randomized to either the rapid palatal expansion (RPE) group or the RPE/C group. Patients aged 7 to 13 years, Class Ⅲ malocclusion, anterior crossbite, ANB less than 0°, Wits appraisal less than -2 mm, and A-Np less than 0 mm were included in the study. The RPE group received rapid palatal expansion, whereas the RPE/C group received alternate rapid palatal expansions and constrictions, and both with facemask protraction. Head orientations of cone-beam computed tomography (CBCT) images were implemented by Dolphin 11.7. 3D measurements of circummaxillary sutures on CBCT images were evaluated using Mimics 10.01 before (T0) and after treatment (T1). The changes were analyzed with independent t test, two-way ANOVA, Pearson correlation and regression analysis. RESULTS: Two subjects in the RPE/C group were lost to follow-up. A total of 34 patients reached the completion criteria and were analyzed. Compared with the RPE group, sagittal changes of circummaxillary sutures were significantly increased in the RPE/C group with 1.21 mm advancement of zygomaticotemporal suture, 2.20 mm of ZMS, 1.43 mm of zygoma-ticofrontal suture (P < 0.05, respectively). Except for the zygomaticotemporal suture, the rest forward sagittal changes of other circummaxillary sutures showed no major difference in terms of the ZMS maturation. The Spearman's correlation in RPE/C indicated a strong positive correlation of sagittal changes between ZMS and point A (P < 0.01) with a regression analysis R²=42.5%. CONCLUSION RPE/C might be more effective on the treatment of maxillary retrusive children. As one of the major mechanical loading sutures during orthopedic therapy, ZMS showed a strong positive correlation with point A on sagittal changes.
Cone-Beam Computed Tomography/methods* ; Constriction ; Humans ; Malocclusion, Angle Class III/therapy* ; Maxilla/diagnostic imaging* ; Palatal Expansion Technique ; Sutures

OBJECTIVE: To explore the method of measuring root volume with cone-beam computed tomography (CBCT) three-dimensional reconstruction technology, and to study root length and root volume of upper and lower central incisors in patients with skeletal Class Ⅲ malocclusion treated by surgical orthodontic treatment. METHODS: Twenty patients with skeletal Class Ⅲ malocclusion undergoing surgical orthodontic treatment were selected. CBCT data at three time points, before decompensation treatment (T0), after decompensation treatment (before orthognathic surgery, T1), and the end of post-operative orthodontic treatment (T2) were collected. Three-dimensional reconstruction technology was used to measure the root length and root volume of the upper and lower central incisors (including total root volume, cervical root and apical root), calculate the percentage of reduction volume, and measure the distance of tooth movement after orthodontic treatment. Data were statistically analyzed by SPSS 20.0 software. Least significant difference (LSD) method was used for pair comparison between the groups subject to normal distribution, and non-parametric test was used for comparison between the groups not subject to normal distribution. The differences of root length and root volume of upper and lower incisors were compared, and the characteristics of root absorption were analyzed. RESULTS: Root length and root volume of the upper and lower central incisors were reduced during the surgical orthodontic treatment (P < 0.05) in cases. Both the root volume of cervical root and apical root were significantly reduced (P < 0.05), the reduction of apical root was more significant. The percentage of root volume reduction of the upper central incisor was (30.51±23.23)%, and lower central incisor (23.24±11.96)%. Compared with the upper central incisor, the root volume reduction amount and percentage of the lower central incisor were smaller, and apical root volume reduction of the upper central incisor was greater than that of the lower central incisor, which was statistically significant (P < 0.05). During pre-surgical orthodontic treatment, maxillary central incisor palatal moving was in a controlled tipping manner, and the mandibular central incisor tipped labially. CONCLUSION In patients with skeletal Class Ⅲ malocclusion, root length and total root volume of upper and lower central incisors decreased during surgical orthodontic treatment. Root volume measurement indicated that the cervical root also had root resorption. The difference in root resorption of the upper and lower central incisors might be related to the distance and direction of teeth movement. CBCT three-dimensional reconstruction will compensate for the limitation of root length measurement in evaluating root resorption.
Cone-Beam Computed Tomography/methods* ; Humans ; Incisor/diagnostic imaging* ; Malocclusion, Angle Class III/surgery* ; Maxilla/surgery* ; Root Resorption/etiology*

OBJECTIVE: To evaluate the difference of features of alveolar bone support under lower anterior teeth between high-angle adults with skeletal class II malocclusions and high-angle adults presenting skeletal class III malocclusions by using cone-beam computed tomography (CBCT). METHODS: Patients who had taken the images of CBCT were selected from the Peking University School and Hospital of Stomatology between October 2015 and August 2017. The CBCT archives from 62 high-angle adult cases without orthodontic treatment were divided into two groups based on their sagittal jaw relationships: skeletal class II and skeletal class III. vertical bone level (VBL), alveolar bone area (ABA), and the width of alveolar bone were measured respectively at the 2 mm, 4 mm, 6 mm below the cemento-enamel junction (CEJ) level and at the apical level. After that, independent samples t-tests were conducted for statistical comparisons. RESULTS: The ABA of the mandibular alveolar bone in the area of lower anterior teeth was significantly thinner in the patients of skeletal class III than those of skeletal class II, especially in terms of the apical ABA, total ABA on the labial and lingual sides and the ABA at 6 mm below CEJ level on the lingual side (P<0.05). The thickness of the alveolar bone of mandibular anterior teeth was significantly thinner in the subjects of skeletal class III than those of skeletal class II, especially regarding the apical level on the labial and lingual side and at the level of 4 mm, 6 mm below CEJ level on the lingual side (P<0.05). CONCLUSION The ABA and the thickness of the alveolar bone of mandibular anterior teeth were significantly thinner in the group of skeletal class III adult patients with high-angle when compared with the sample of high-angle skeletal class II adult cases. We recommend orthodontists to be more cautious in treatment of high-angle skeletal class III patients, especially pay attention to control the torque of lower anterior teeth during forward and backward movement, in case that the apical root might be absorbed or fenestration happen in the area of lower anterior teeth.
Adult ; Alveolar Process/diagnostic imaging* ; Cephalometry ; Cone-Beam Computed Tomography ; Humans ; Incisor ; Malocclusion, Angle Class III/diagnostic imaging* ; Mandible/diagnostic imaging*

OBJECTIVETo evaluate the alveolar bone thickness and root length changes of anterior teeth with cone-beam computed tomography (CBCT).

METHODSCBCT scans were taken for 12 skeletal Class III patients who accepted the improved corticotomy (IC) procedures during pre-surgical orthodontics. The CBCT data in T1 (the maxillary dental arch was aligned and leveled) and T2 (extraction space closure) were superimposed and the alveolar bone thickness at root apex level and root length measurements were done.

RESULTSFrom T1 to T2, the buccal alveolar bone thickness for the upper lateral incisors increased from (1.89±0.83) to (2.47±1.02) mm (P<0.05), and for central incisors and for canines from (2.32±0.71) to (2.68±1.48) mm and from (2.28±1.08) to (2.41±1.40) mm, respectively. According to Sharpe Grading System, the root resorption grade for 69 teeth of 72 was located in Grade 1, two teeth in Grade 2, one tooth in Grade 3.

CONCLUSIONSThe improved corticotomy had the potential to increase the buccal alveolar bone thickness and the root resorption in most teeth was in Grade 1 according to Sharpe grading system.

Alveolar Process ; anatomy & histology ; diagnostic imaging ; surgery ; Cone-Beam Computed Tomography ; Cuspid ; Humans ; Incisor ; Malocclusion, Angle Class III ; diagnostic imaging ; surgery ; Root Resorption ; pathology ; Tooth Root ; Zygoma

OBJECTIVETo investigate the tongue movement during swallowing in skeletal Class III adult patients using M-mode ultrasonography combined with cushion scanning technique.

METHODSTongue movement during swallowing in 20 skeletal Class III adult patients (11 females, 9 males, mean age 20.5 years) and 11 healthy adults (8 females, 3 males, mean age 23.5 years) was examined with M-mode ultrasonography combined with cushion scanning technique. The results were compared.

RESULTSCompared with mature swallowed, the skeletal Class III adult patients had longer phase 2 [(0.24 +/- 0.07) s], phase 3 [(1.17 +/- 0.21) s], longer total duration [(1.98 +/- 0.24) s], faster speed in phase 1 [(3.20 +/- 1.30) mm/s], and smaller range in phase 5 [(0.38 +/- 0.28) mm].

CONCLUSIONSThe skeletal Class III adult patients had distinctly different tongue movements during swallowing.

Adolescent ; Case-Control Studies ; Deglutition ; Female ; Humans ; Male ; Malocclusion, Angle Class III ; diagnostic imaging ; physiopathology ; Tongue ; diagnostic imaging ; Ultrasonography ; Young Adult

OBJECTIVETo evaluate the short-term and long-term effects of pharyngeal airway in mandibular prognathism patients after the combined orthodontic and orthognathic treatment.

METHODSThe sample included 28 skeletal Class III patients (13 males, 15 females) who had undergone mandibular setback surgery and orthodontic treatment. Cone-beam CT was taken one week before treatment (T0), 6 months (T1) and 3 years after surgery (T2). Raw data were reconstructed into three-dimensional model. Sagittal and transversal measurements, cross sectional areas, partial and total volumes were computed.

RESULTSSix months after surgery, oropharyngeal volume [(9 021 ± 4 263) mm³], hypopharyngeal volume [(9 236 ± 5 963) mm³] and total volume [(28 619 ± 9 854) mm³] decreased significantly (P < 0.05). Three years after surgery, only sagittal diameters [(15.9 ± 3.5) mm] and cross sectional areas [(996 ± 398) mm²] in the first cervical vertebra plane came back to the original levels (P > 0.05).

CONCLUSIONSThe pharyngeal airway space decreased after orthodontic-orthognathic therapy in the short term and it increased in some areas in the long term.

Cephalometry ; Cone-Beam Computed Tomography ; Female ; Humans ; Hypopharynx ; anatomy & histology ; diagnostic imaging ; Male ; Malocclusion, Angle Class III ; diagnostic imaging ; surgery ; Oropharynx ; anatomy & histology ; diagnostic imaging ; Osteotomy, Le Fort ; Osteotomy, Sagittal Split Ramus ; Pharynx ; anatomy & histology ; diagnostic imaging ; Time Factors

Based on the anatomic structure of a girl with class III skelet al malocclusion, a three-dimensional finite element biomechanical model of facial soft tissue was established. With the use of this model, three surgery plans of distraction osteogenesis, LeFort I, II, III maxillary complex advancement in the direction of functional occlusal plane, were simulated. As a result, the facial soft tissue deformation was predicted and the ratio of the facial location deformation to the free bone advancement was calculated. The facial shape after surgery could be viewed in 3D. In addition, the location of center of resistance was investigated when the free bone was protracted forward in the process of LeFort I maxillary complex advancement; it was located at a site about 30 mm posterior to the soft tissue A point. The research result indicates that three-dimensional finite element research on distraction osteogenesis can provide instruction for setting the suitable protraction point and direction of the protraction force in surgery, and by predicting the facial soft tissue deformation, it also can provide the surgeon and patient with information on the options and reference to the surgery plans.
Adolescent ; Cephalometry ; Computer Simulation ; Face ; diagnostic imaging ; pathology ; surgery ; Female ; Finite Element Analysis ; Humans ; Imaging, Three-Dimensional ; Malocclusion, Angle Class III ; diagnostic imaging ; pathology ; surgery ; Maxilla ; diagnostic imaging ; pathology ; surgery ; Models, Biological ; Osteogenesis, Distraction ; instrumentation ; Osteotomy ; Radiography

OBJECTIVETo analyze the three-dimensional changes of pharyngeal airway in patients with skeletal Class III malocclusion after the combined orthodontic and orthognathic treatment.

METHODSTwenty patients (9 males, 11 females) and 40 subjects with normal occlusion were involved in the study. Cone-beam computed tomography (CBCT) were performed on patients one week and six months after treatment. Raw data were reconstructed into three-dimensional model and sagittal and transversal measurements, cross sectional areas, partial and total volumes were computed.

RESULTSAfter treatment, the sagittal diameters of each section were significantly reduced by (2.7 ± 3.5), (3.0 ± 3.8), (2.7 ± 3.3) mm, respectively (P < 0.05). The transversal diameter of laryngopharyngeal airway constricted significantly by (4.8 ± 4.1) mm (P < 0.05). Cross sectional areas and volumes of each part in patients after surgery were significantly narrower compared with those of the controls.

CONCLUSIONSAfter combined therapy the pharyngeal airway space decreased.

Adolescent ; Adult ; Cone-Beam Computed Tomography ; Female ; Humans ; Hypopharynx ; diagnostic imaging ; Imaging, Three-Dimensional ; Male ; Malocclusion, Angle Class III ; diagnostic imaging ; surgery ; therapy ; Orthodontics, Corrective ; Osteotomy, Sagittal Split Ramus ; Pharynx ; diagnostic imaging ; Young Adult