The odontogenic keratocyst (OKC) is a developmental odontogenic cyst typically occurring in the jaws. Since the first description of OKC was published in 1956, the lesion has been of particular interest because of its specific histopathologic features, high recurrence rate, and aggressive behavior. Recurrences most commonly arise within bone at the site of the original cyst. However, as lining cells may find their way into surrounding tissues either from implantation during surgery or from cortical perforation recurrences may arise at a distance from the original cyst. Here, we report a rare case of recurrent OKC which was first developed in mandible and recurred within the masticatory space.
Diagnostic Imaging ; Jaw ; Mandible ; Masticatory Muscles ; Odontogenic Cysts ; Recurrence

OBJECTIVE: To explore more concise and unified forensic identification indexes for people with none dental disease in digital orthopantomogram. METHODS: To select randomly 170 digital orthopantomogram with none dental disease. Then to select indexes for full dentition patterns and dental alignment patterns according to the dental physiological variations and the characters of dental alignment respectively. Finally diversity of the indexes would be evaluated by statistical analysis. RESULTS: The group with none dental disease had 74 kinds of full dentition pattern in 170 samples, thus its diversity was 43.53%. The group had 129 kinds of dental alignment pattern, thus its diversity was 75.88%. The group had 150 kinds of full dentition/dental alignment pattern, thus its diversity was 88.24%. CONCLUSION The diversity of the full dentition pattern was not very good. So the full dentition coding was not very effective when it was used solely. The diversity of dental alignment pattern was good. So the method of dental alignment coding could be used in the maxillofacial forensic identification. If the group was coded by the full dentition and dental alignment pattern at the same time, its diversity was better than any single pattern. So the method would be valuable in forensic identification.
Dentition ; Forensic Dentistry ; Humans ; Mandible/diagnostic imaging* ; Maxilla/diagnostic imaging* ; Radiography, Dental, Digital ; Radiography, Panoramic/methods*

OBJECTIVES: The aim of this study was to compare the anterior and posterior occlusal plane characteristics of patients with different temporomandibular joint osseous statuses. METHODS: A total of 306 patients with initial cone beam CT (CBCT) and cephalograms were included. They were divided into three groups on the basis of their temporomandibular joint osseous status: bilateral normal (BN) group, indeterminate for osteoarthrosis (I) group, and osteoarthrosis (OA) group. The anterior and posterior occlusal planes (AOP and POP) of the different groups were compared. Then, the regression equation was established after adjusting for confounding factors, and a correlation analysis between the occlusion planes and other parameters was performed. RESULTS: SNA, SNB, FMA, SN-MP, Ar-Go, and S-Go were correlated with the occlusal planes. Relative to the BN and I groups, the FH-OP of the OA group increased by 1.67° on the average, FH-POP increased by 1.42° on the average, and FH-AOP increased by 2.05° on the average. CONCLUSIONS The occlusal planes were steeper in the patients with temporomandibular osteoarthrosis than in the patients without it, and the mandible rotated downward and backward. The height of the mandibular ramus, the mandibular body length, and the posterior face height were small. In clinical practice, attention should be given to the potential risk of temporomandibular joint osteoarthrosis in such patients. In addition, SNB, FMA, SN-MP, Ar-Go, S-Go, and occlusal planes had moderate correlations.
Humans ; Dental Occlusion ; Cephalometry ; Mandible ; Temporomandibular Joint Disorders/diagnostic imaging* ; Temporomandibular Joint/diagnostic imaging* ; Osteoarthritis/diagnostic imaging* ; Mandibular Condyle

OBJECTIVETo investigate the change of skeleton structure and masseter after mandibular angle osteotomy and its clinical significance in preoperative design.

METHODS3-dimensional CT cephalometry was performed before and after surgery in 18 cases of prominent mandibular angle.

RESULTSPre- and post-operative data were compared. Significant differences between the pre- and post-operative data were found in the mandibular angle, the distance between mandibular angle, length of ramus, ectropion angle of mandibular angle, triangle Go-Me-Go, the thickness, width and length of masseter.

CONCLUSIONSIt indicates the skeleton structure is changed and some kind of atrophy happens in the masseter after operation. So we suggest partial resection of masseter should be unnecessary for mandibular angle osteotomy.

Cephalometry ; methods ; Facial Bones ; diagnostic imaging ; Female ; Humans ; Imaging, Three-Dimensional ; Mandible ; diagnostic imaging ; Masseter Muscle ; diagnostic imaging ; Osteotomy ; Skull ; diagnostic imaging ; Tomography, X-Ray Computed ; Young Adult

OBJECTIVETo investigate the prevalence and configuration of the isthmuses in the apical 6 mm of the mesial and distal roots of Chinese mandibular first molar by means of micro-computed tomography.

METHODSThirty-six extracted human mandibular first molars were selected. Specimens were subject to micro-CT and a slice thickness of 30 microm was obtained in the apical 6 mm of the roots examined. The number of sections showing isthmuses at each apical level was recorded. Three-dimensional images of isthmuses of mandibular first molars were reconstructed and observed.

RESULTSThe mesial roots of human mandibular first molars had a high incidence of isthmus. The isthmus incidence was greatest 4-6 mm from the apex in human mandibular first molar, with prevalence figures of 49.5%-66.1% and 17.3%-17.8% in mesial and distal roots, respectively. The chi-square test indicated a significant difference in the distribution of isthmuses between the two roots (P < 0.01).

CONCLUSIONSThe mesial roots of human mandibular first molars have a high incidence of isthmus, which may have clinical implications especially when surgical endodontics is performed on the mesial roots of mandibular molars.

Adult ; Dental Pulp Cavity ; diagnostic imaging ; Humans ; Imaging, Three-Dimensional ; Mandible ; diagnostic imaging ; Molar ; diagnostic imaging ; Root Canal Therapy ; Tooth Root ; diagnostic imaging ; X-Ray Microtomography

OBJECTIVETo evaluate the degree and pattern of alveolar bone defect in aggressive periodontitis (AgP) using cone-beam CT (CBCT), and to investigate the distribution of alveolar bone defects in aggressive periodontitis.

METHODSForty AgP patients (age: 14-36 years, male: 15 cases, female: 25 cases) were selected by simple random method and scanned by CBCT. NNT software was applied to measure the average degree of alveolar bone defects and bone loss types in different regions.

RESULTSIn forty AgP patients, 86.6% (3,769/4,352) sites presented moderate and severe alveolar bone defects. In the maxilla, the molar areas presented the heaviest alveolar bone defect [(6.3±0.7) mm], the canine areas showed the lightest bone loss [(4.8±0.8) mm]. In the mandible, the incisal areas presented the heaviest alveolar bone defect [(5.9±0.9) mm], the canine areas showed the lightest bone loss[(5.1±0.7) mm]. The degree of alveolar bone defect in the areas of maxillary canine, maxillary molars, mandibular premolar was significantly different (P<0.05). The degree of alveolar bone defect in mandibular canine and mandibular molars was significantly differenct (P<0.01). The most serious alveolar bone defect was in the mesial side of maxillary molar [(6.9±0.7) mm] and the mesial side of mandibular incisor [(6.5±1.1) mm]. The oblique bone defects were found in the mesial part of the first molars in mandibula [13.6% (42/308)], the first molars in maxilla [12.0% (39/316)] and the first premolar in maxilla [10.8% (34/316)].

CONCLUSIONSThe alveolar bone defects of generalized AgP patients were serious. The most serious areas were located in the mesial side of maxillary molars and the mesial side of mandibular incisor.

Adolescent ; Adult ; Aggressive Periodontitis ; diagnostic imaging ; Alveolar Process ; diagnostic imaging ; Bicuspid ; Cone-Beam Computed Tomography ; Cuspid ; Female ; Humans ; Incisor ; Male ; Mandible ; diagnostic imaging ; Maxilla ; diagnostic imaging ; Molar ; Software

Objective: To investigate the shape and position changes of temporomandibular joint (TMJ) in adult skeletal class Ⅱ malocclusion with high angle patients after vertical mandibular control, and the correlation between vertical mandibular changes and condylar position changes. Methods: Twenty adult skeletal class Ⅱ malocclusion with high angle patients [6 males and 14 females, aged (21.4±2.4) years] who underwent extraction treatment and active vertical control in the Department of Orthodontics, Lanzhou University Stomatological Hospital from October 2017 to November 2020 were selected. Cone-beam CT data of the patient before and after treatment were imported into Invivo Dental 5.0 software for three-dimensional reconstruction and correction, and the vertical index of mandible in reconstructed lateral cephalogram (mandibular plane angle, posterior anterior height ratio, mandibular true rotation angle) were measured. Incisal angle and variables of condyle shape, position and articular fossa shape were measured. Paired t test was performed on the results before and after treatment, and the correlation between mandibular vertical changes and condylar position changes was determined by Pearson correlation coefficient calculation. Results: After treatment, the overbite and overjet were within normal range, and the vertical height of the molars was controlled. Compared with the measurement before treatment, mandibular plane angle and mandibular true rotation angle were decreased by 2.05°±1.22° (t=7.60, P<0.001) and 1.42°±1.92° (t=3.54, P=0.002), respectively. The posterior anterior height ratio was increased by (1.89±3.32)% (t=2.56, P=0.019). After treatment, the mediolateral diameter of condyle, the anteroposterior diameter of condyle, the maximum cross-sectional area of condyle, the height of condyle head, the width of articular fossa, the depth of articular fossa and the articular nodular angle were increased by (0.55±0.76) mm (t=-2.73, P=0.015), (0.27±3.51) mm (t=-3.23, P=0.006), (6.01±7.36) mm² (t=-2.80, P=0.013), (0.33±0.72) mm (t=-2.14, P=0.046), (0.56±0.93) mm (t=-2.37, P=0.032), 0.33 (0.14, 0.51) mm (Z=-2.76, P=0.006) and 1.50°±2.40° (t=-2.44, P=0.028), respectively. The internal condylar space and the external condylar space were decreased by (0.33±0.49) mm (t=2.31, P=0.035) and (0.20±0.23) mm (t=3.58, P=0.003), respectively. Before orthodontic treatment, 6 patients were with anterior displacement of the condyle, 7 patients with central position of the condyle, and 7 patients with posterior displacement of the condyle. After correction, patients who were with central position of the condyle have not changed much. The posterior displaced condyle in 2 patients and anterior displaced condyle in 3 patients became in central position after treatment. The joint space index was closer to the central position in 3 patients with anterior displacement and 3 patients with posterior displacement. The position of condyle in 1 patient with posterior displacement and 1 patient with anterior displacement remained basically unchanged. There was a significant negative correlation between the change of the posterior-anterior height ratio and the change of the internal condylar space in patients (r=-0.52, P=0.019), and a low correlation with the contral condylar space and the external condylar space(r=-0.48, P=0.031; r=-0.47, P=0.035). Conclusions: Skeletal class Ⅱ malocclusion with high angle adult patients achieved normal overbite and overjet and remodeling of condyle and articular fossa occurred after orthodontic treatmnet and vertical control. There was a certain negative correlation between the change of posterior-anterior height ratio and the change of condylar position.
Adult ; Female ; Humans ; Male ; Cone-Beam Computed Tomography ; Malocclusion, Angle Class II/diagnostic imaging* ; Mandible/diagnostic imaging* ; Mandibular Condyle/diagnostic imaging* ; Overbite ; Temporomandibular Joint/diagnostic imaging*

Precision registration of serial sections is an important step for 3-D image reconstruction. It directly affects the accuracy of the reconstructed result and parameter computation. This problem has been studied and demonstrated by many investigators, but the whole process has not yet reached good performance. In this paper, we discussed the registration of serial sections image of mandible and put forward a method of the soft registration-based transformation on the basis of the hard registration in consideration of the speciality of 3-D image reconstruction for the serial sections of mandible. Employing control points and using Affine Transformation and Extended Hough Transformation, we solved the problem of displacement on 3-D image reconstruction for serial secons and paved the way for reconstructing the mandible microstructure with reality. The results of experiments indicate that the 3D image reconstructed after registration has only a little distortion.
Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional ; Mandible ; diagnostic imaging ; Tomography, X-Ray Computed

OBJECTIVE: To explore an efficient and automatic method for determining the anatomical landmarks of three-dimensional(3D) mandibular data, and to preliminarily evaluate the performance of the method. METHODS: The CT data of 40 patients with normal craniofacial morphology were collected (among them, 30 cases were used to establish the 3D mandibular average model, and 10 cases were used as test datasets to validate the performance of this method in determining the mandibular landmarks), and the 3D mandibular data were reconstructed in Mimics software. Among the 40 cases of mandibular data after the 3D reconstruction, 30 cases that were more similar to the mean value of Chinese mandibular features were selected, and the size of the mandibular data of 30 cases was normalized based on the Procrustes analysis algorithm in MATLAB software. Then, in the Geomagic Wrap software, the 3D mandibular average shape model of the above 30 mandibular data was constructed. Through symmetry processing, curvature sampling, index marking and other processing procedures, a 3D mandible structured template with 18 996 semi-landmarks and 19 indexed mandibular anatomical landmarks were constructed. The open source non-rigid registration algorithm program Meshmonk was used to match the 3D mandible template constructed above with the tested patient's 3D mandible data through non-rigid deformation, and 19 anatomical landmark positions of the patient's 3D mandible data were obtained. The accuracy of the research method was evaluated by comparing the distance error of the landmarks manually marked by stomatological experts with the landmarks marked by the method of this research. RESULTS: The method of this study was applied to the data of 10 patients with normal mandibular morphology. The average distance error of 19 landmarks was 1.42 mm, of which the minimum errors were the apex of the coracoid process [right: (1.01±0.44) mm; left: (0.56±0.14) mm] and maximum errors were the anterior edge of the lowest point of anterior ramus [right: (2.52±0.95) mm; left: (2.57±1.10) mm], the average distance error of the midline landmarks was (1.15±0.60) mm, and the average distance error of the bilateral landmarks was (1.51±0.67) mm. CONCLUSION The automatic determination method of 3D mandibular anatomical landmarks based on 3D mandibular average shape model and non-rigid registration algorithm established in this study can effectively improve the efficiency of automatic labeling of 3D mandibular data features. The automatic determination of anatomical landmarks can basically meet the needs of oral clinical applications, and the labeling effect of deformed mandible data needs to be further tested.
Humans ; Imaging, Three-Dimensional/methods* ; Mandible/diagnostic imaging* ; Software ; Algorithms ; Anatomic Landmarks/anatomy & histology*

OBJECTIVETo decrease the incidence of inferior alveolar neurovascular bundle injury through location of mandibular canal by 3-dimensional (3-D) CT.

METHODS30 female cases with prominent mandibular angle underwent 3-D CT before operation. The 3-D images were used to measure the distances between upper points of lower teeth to the inferior border of the canal. Then the osteotomy was designed according to the canal position to avoid the inferior alveolar neurovascular bundle injury. The canal protection was observed intraoperatively and postoperatively.

RESULTSThe mandibular canal was protected very well in all 30 cases without any injury to the inferior alveolar neurovascular bundle.

CONCLUSIONSThe 3-D CT can accurately locate the mandibular canal to guide the design of the mandibular angle osteotomy for patients with prominent mandibular angle.

Adult ; Female ; Humans ; Imaging, Three-Dimensional ; Mandible ; diagnostic imaging ; innervation ; surgery ; Mandibular Nerve ; diagnostic imaging ; Neural Tube ; diagnostic imaging ; Tomography, X-Ray Computed