Research status and outlook of deep learning in oral and maxillofacial medical imaging / 中华口腔医学杂志

Artificial intelligence, represented by deep learning, has received increasing attention in the field of oral and maxillofacial medical imaging, which has been widely studied in image analysis and image quality improvement. This narrative review provides an insight into the following applications of deep learning in oral and maxillofacial imaging: detection, recognition and segmentation of teeth and other anatomical structures, detection and diagnosis of oral and maxillofacial diseases, and forensic personal identification. In addition, the limitations of the studies and the directions for future development are summarized.

Research status and outlook of deep learning in oral and maxillofacial medical imaging / 中华口腔医学杂志

Artificial intelligence, represented by deep learning, has received increasing attention in the field of oral and maxillofacial medical imaging, which has been widely studied in image analysis and image quality improvement. This narrative review provides an insight into the following applications of deep learning in oral and maxillofacial imaging: detection, recognition and segmentation of teeth and other anatomical structures, detection and diagnosis of oral and maxillofacial diseases, and forensic personal identification. In addition, the limitations of the studies and the directions for future development are summarized.

Computed tomographic features of desmoplastic ameloblastoma of the jaw / 北京大学学报(医学版)

OBJECTIVE@#To retrospectively analyze the clinical and CT imaging features of desmoplastic ameloblastomas (DA) in comparison with other types of ameloblastomas.@*METHODS@#Patients diagnosed with ameloblastoma histopathologically in Peking University School and Hospital of Stomatology from July 2000 to August 2017 were reviewed to analyze the constituent ratios and characteristics of DA. CT imaging features of DA (28 cases) were investigated in comparison with consecutive cases of solid/multicystic and unicystic ameloblastomas. The following imaging perspectives were analyzed: the border, internal structure, three-dimensional shape, tooth, the periodontium, the cortex and the expansion of the tumors. CT values were measured in the region of interest for quantitative analysis.@*RESULTS@#Among the 1 269 cases of ameloblastomas, 50 (3.9%) were DA, which showed predilections for males (74.0%). The average age of DA was about 43.9 years old, which was higher than the other two types. The anterior incisorcanine region (62.0%) and premolar region (30.0%) were most frequently affected. The incidence rate of DA in mandibule was 56.0% (28/50), which was slightly higher than that of maxilla (44.0%). The DA characteristically showed scallop border and honeycomblike or soapbubble internal structure with bone formation on CT. The mean ratios of height to mesiodistal and buccal-lingual to mesio-distal distances were 0.76 and 0.63, which were higher than the other two types. According to the degree of internal bone formation, three subtypes of DA could be observed: densely ossifying type (I), honeycomb/soap bubble type (II) and sparsely ossifying type (III). The means and standard deviations of CT values of DA were significantly higher than those of the other two types, which were (488.8±164.0) HU (type I), (171.7±102.8) HU (type II), (42.1±8.8) HU (type III).@*CONCLUSION@#CT is helpful for diagnosis of DA, which shows as solid tumor with varying degrees of internal ossification.

CT imaging features of diffuse tenosynovial giant cell tumor of temporomandibular joint / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study aimed to investigate the characteristic features of CT images of diffuse tenosynovial giant cell tumor (D-TSGCT) from the temporomandibular joint (TMJ) to understand CT imaging diagnosis of the disease.</p><p><b>METHODS</b>CT images and clinical information from 10 patients with D-TSGCT of TMJ were recruited for retrospective analysis from March 2013 to March 2017 in Peking University Hospital of Stomatology. All cases were treated by surgery and confirmed by pathology.</p><p><b>RESULTS</b>CT scan demonstrated hyperdense soft-tissue masses and various kinds of calcification in all of the 10 subjects. Contrast-enhanced scan exhibited obvious enhancement in six patients. Bone destruction of the mandibular condyles and skull base was found in seven and six subjects, respectively.</p><p><b>CONCLUSIONS</b>CT appearance of D-TSGCT of the TMJ is characterized by hyperdense soft tissue with calcification, further enhancement in contrast-enhanced scan, and bone destruction in the mandibular condyles and skull base in some cases.</p>

Radiological characteristics of the cyst-like lesion of condyle in temporomandibular joint by cone beam computed tomography / 华西口腔医学杂志

OBJECTIVE@#To analyze the radiological characteristics and classifications of the cyst-like lesion of condyle in temporomandibular joint (TMJ) by cone beam computed tomography (CBCT).@*METHODS@#The study was conducted retrospectively on TMJ images from 194 patients who underwent CBCT examinations. Location, size, amount, surrounding bone trabecula, cortical bone white line of cyst-like lesion, and the overall condition of the condylar bone were evaluated. According to the overall condition of the condylar bone, the cyst-like lesion of condyle were divided into typesⅠand Ⅱ. The location, size, amount, surrounding bone trabecula, and cortical bone white line of the two types of cyst-like lesions were compared.@*RESULTS@#In 198 condylars of 194 patients, cyst-like lesions were detected in the left side of 94 patients, in the right of 96 patients, and in both sides of 4 patients. The size of lesions ranged from 1.2 mm to 13.5 mm, with an average size of (3.4±1.5) mm. Half of the cyst-like lesions were located underneath the anterior lateral cortical bony layer (99 condylars, 50.0%). Most cyst-like lesions were solitary (149 condylars, 75.3%), while 62.6% (124 condylars) were surrounded by continuous bony white lines. Bone sclerosis could be observed in 160 condylars (80.8%). A total of 132 condyles (66.7%) were accompanied by changes in late-stage osteoarthrosis, while the others were only accompanied by early-stage osteoarthrosis (10 osteoarthrosis, 5.1%) or showed no evidence of osteoarthrosis (56 osteoarthrosis, 28.3%). Statistical difference were observed in the location, amount, and surrounding bone trabecula of the two types of cyst-like lesions. TypeⅠcyst-like lesions had more frequent and bone sclerosis than type Ⅱ, whereas type Ⅱ cyst-like lesions occurred more on condylar internal or condyle neck than typeⅠ.@*CONCLUSIONS@#The pathogenesis and mechanism of the two types of cyst-like lesions may be different from each other.

Classification and clinical characteristics of masticatory myospasm / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To determine the classification of masticatory myospasm by analyzing characteristics of clinical appearances.</p><p><b>METHODS</b>Thirty-six cases of masticatory myospasm from 2000 to 2010 were included. The clinical data of these patients were analyzed, including patient information, patient history, clinical characteristics, severity and the frequency of myospasmodic movement, electromyogram (EMG), and the efficacy of botulinum toxin injection treatment.</p><p><b>RESULTS</b>There were 11 males and 25 females, aged from 15 to 71. According to the clinical manifestation and EMG findings, patients could be divided into two groups: 18 cases were classified as jaw closing type which involved masseter and/or temporalis muscles presenting as trismus and acute pain, the other 18 cases were jaw opening type which involved lateral pterygoid muscles complaining difficulty in jaw closing and teeth clenching. The jaw closing type was often seen in patients of 20 to 50 years old, the jaw opening was frequently seen in patients over 50 years old. Jaw closing type was attacked intermittently and unilaterally, but jaw opening was often attacked continually and bilaterally. The rating scale of the severity of spasmodic movement was not different between the two types, but the frequency of spasmodic attack was much higher for jaw opening type (P < 0.05). The EMG of jaw closing type was classified into persistent, rhythmic and irregular type. The EMG of jaw opening type was classified into spontaneous and exercise-induced type. Twelve cases were treated by botulinum toxin injection that could significantly relieve symptoms.</p><p><b>CONCLUSIONS</b>Masticatory myospasm can be classified into jaw closing and jaw opening types. Jaw closing type involves masseter and/or temporalis muscles and jaw opening type involves lateral pterygoid muscles. Botulinum toxin injection was the most effective therapy for the masticatory myospasm.</p>

Clinical natural course of temporomandibular joint intermittent closed lock / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the clinical natural course of temporomandibular joint (TMJ) intermittent closed lock (ICL) through 24 months follow-up.</p><p><b>METHODS</b>Sixty-eight patients with ICL were included, and 54 patients finished 24 months follow-up. The disease duration, frequency of joint lock and joint pain were recorded at the patient's first visit. Telephone interviews were taken for every month, and the frequency of joint lock and joint pain were recorded. According to the development of ICL, the patients were divided into 3 groups: symptom-worsened group, symptom-disappeared group, symptom-persisted group.</p><p><b>RESULTS</b>There were 16 patients (30%) whose symptoms worsened into closed lock (disk displacement without reduction), 32 patients (59%) whose symptoms persisted during the 24 months follow-up, and 6 patients' (11%) symptoms disappeared. In symptom-persisted group, the frequency of joint lock decreased in 11/32 (34%), increased in 4/32 (13%), did not change in 17/32 (53%). There was no significant difference in gender, age, frequency of joint lock and joint pain recorded at the first visit among these 3 groups (P > 0.05). The disease duration in the symptom-disappeared group was much shorter than the other 2 groups (P < 0.05).</p><p><b>CONCLUSIONS</b>ICL of TMJ was more likely to get worse into closed lock. There seemed no significant relation between the sequelaes of ICL and patients' gender, age, disease duration, frequency of joint lock and joint pain, and larger sample studies were necessary.</p>

Influence of intra-articular corticosteroid on the efficacy of arthrocentesis in treatment of temporomandibular joint anterior disc displacement without reduction / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To compare the efficacy and radiographic changes after arthrocentesis followed or not followed by intra-articular corticosteroid injection in patients with temporomandibular disc displacement without reduction.</p><p><b>METHODS</b>Ninty patients were enrolled in the randomized clinical trial. After receiving arthrocentesis, either 0.5 mL triamcinolone acetonide plus 0.5 mL saline (experimental group, n = 46) or 1 mL saline solution as control (control group, n = 44) was injected. Patients were assessed by visual analogue scale (VAS) pain scores and Fricton temporomandihular joint (TMJ) index at first visit before treatment, 3-4 weeks and 6 months after treatment respectively. Transpharyngeal and lateral transcranial projections for temporomandibular joints were taken for imaging evaluation. The pain score of patients with pain complaint were recorded everyday for 1 week after treatment.</p><p><b>RESULTS</b>Glucocorticoid injection showed more effective pain control over the first week (P < 0.05), and both groups reported symptom and clinical sign relief significantly after treatment (P< 0.001). However, quantitative evaluation for pain reduction, maximal mouth opening improvement and Friction TMJ index showed no significant difference between two groups at 3-4 weeks and 6 months after the treatment. Also there was no significant difference for condylar bone changes radiographically between the two groups.</p><p><b>CONCLUSION</b>Arthrocentesis is an effective treatment for temporomandibular joint disc displacement without reduction, but it is not necessary to inject corticosteroid after arthrocentesis. Intra-articular corticosteroid injection after arthrocentesis is indicated for only those patients with severe pain.</p>

Positional changes of temporomandibular joint disk and condyle with insertion of anterior repositioning splint / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To measure the positional changes of temporomandibular joint (TMJ) disk and condyle with insertion of anterior repositioning splint (ARS) using magnetic resonance imaging (MRI) for further understanding of the splint therapy mechanisms.</p><p><b>METHODS</b>Twenty-two patients with temporomandibular joint clicks were included. 31 TMJs were diagnosed as anterior disk displacement with reduction (disk-displaced group), and the other 13 TMJs were normal (normal group). All joints were scanned oblique-sagittally by MRI before splint treatment in three positions including closed-mouth position of centric occlusion (the position before insertion of ARS), incisors' edge to edge position, and mandibular least forward protrusion position (the position after insertion of ARS).</p><p><b>RESULTS</b>1) Disk-condyle angle: In closed-mouth position, the average angle was 54.23 degrees in the disk-displaced group, while it was 9.80 degrees in the normal group; in incisors' edge to edge position and mandibular least forward protrusion position, the angle was reduced to normal in most of the disk-displaced cases. 2) Disk position: From closed-mouth position to incisors' edge to edge position or mandibular least forward protrusion position, the forward displaced disk moved backward significantly, while the disk with normal position did not change significantly in the three positions. 3) Condyle position: From closed-mouth position to incisors' edge to edge position or mandibular least forward protrusion position, the condyle moved forward and downward significantly both in the disk-displaced group and in the normal group.</p><p><b>CONCLUSION</b>With insertion of the splint, the condyle moved anteriorly and inferiorly and the disk moved posteriorly, most of the anterior displaced disks could be reduced to normal positions in the joint fossa. The result indicated that the splint protruded condyle forward and prevented the backward reduced disk from displacing forward again during mouth closing.</p>

The related factors of bruxism in children / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the related factors of children bruxism.</p><p><b>METHODS</b>Data of 117 children with primary and mixed dentition of 4-10 years of age were collected in the present study. There were 59 children in bruxism group and 58 children in control group. Oral and temporomandibular joint examinations were carried out on each child, and the parents were asked to fill the questionnaires. The data were statistically analyzed, and the relationship between the factors and the occurrence of bruxism was examined.</p><p><b>RESULTS</b>The odd ratio (OR) for psychology factor, occlusal factor, specific sleep posture, parents heredity and relatives heredity were 1.074, 1.528, 4.472, 11.164 and 8.757, respectively.</p><p><b>CONCLUSIONS</b>Psychology factor, occlusal factor, specific sleep posture and heredity factor are the related factors of children bruxism.</p>

Investigation on clinical pain features in temporomandibular disorders / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the pain features of temporomandibular disorders (TMD) by qualitatively and quantitatively analyzing patient multi-dimension sensations.</p><p><b>METHODS</b>Two hundred and fifty patients with painful TMD from January to December 2005 were included, short-form mcgill pain questionnaire (SF-MPQ) and visual analog scale (VAS) were administered to assess patients' sensation, affection and intensity of pain. The data were analyzed by SAS 8.0 software.</p><p><b>RESULTS</b>All patients were assigned to three groups including 139 joint pain, 47 muscle pain and 64 both joint and muscle pain group. In joint pain group, the total number of descriptors was 250, 1.80 in average; in muscle pain group, the total number was 99, 2.11 in average; in both joint and muscle pain group, the total number was 107, 1.64 in average. The sensitive descriptors most frequently chosen in all three groups were "aching", "heavy", and "tender". "Tiring-exhausting" and "sickening" were high frequency descriptors in affective items. There were higher affective scores in the muscle pain group than in others. Muscle pain group had a higher VAS score at rest than the other two (P < 0.05), but had a lower VAS score during function than the other two (P < 0.001). All three groups usually had no pain at rest, and complained a slight to moderate pain during function.</p><p><b>CONCLUSIONS</b>TMD pain was generally slight to moderate; "aching", "heavy", and "tender" were the most frequently sensitive descriptors, while unpleasant feelings were described as "tiring-exhausting" and "sickening"; pain generally occurred or exacerbated during mandibular function; compared to joint pain, muscle pain had its own features.</p>

Evaluation of patients' temporomandibular joint function after mandible reconstruction with free fibula flap / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the temporomandibular joint (TMJ) function after mandible reconstruction with free fibula flap and with different condyle treatment.</p><p><b>METHODS</b>Forty-one cases of mandible and condyle defects following benign tumor resection were reconstructed with fibula free flap, with the condyle being reconstructed by three methods: placement of the distal end of the fibula flap into the glenoid fossa, the fibula serving as the condyle (24 cases); attachment of the resected condyle as a nonvascularized transplant to the end of the fibula flap (5 cases); condyle preservation plus vascularized fibular reconstruction (12 cases). The postoperative TMJ function was evaluated by Fricton function index.</p><p><b>RESULTS</b>No TMJ ankylosis occurred in all patients. There were no significant differences in aesthetics, deglutition and speech function among the three groups; but there were significant differences in TMJ function index (DI, CMI) among different condyle treatments. Condylar preservation showed better TMJ function than fibula used as a substitute for condyle.</p><p><b>CONCLUSIONS</b>Preservation of condyle during free fibula mandibular reconstruction can improve patients' TMJ function. The location and shape of fibular condyle were important factors that could influence the outcome the condyle reconstruction.</p>

Central mechanisms of masticatory muscle pain induced by occlusal interference / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study c-fos and substance P expression in the central nervous system following mechanical and chemical nociceptive stimulation to the masseters in rats with occlusal interference.</p><p><b>METHODS</b>Occlusal interference was made by bonding a 2 mm long dentin screw in the pulp cavity of the first maxillary molar in the left side. Seven days after occlusal interference, the rats in occlusal interference and mechanical stimulus group and mechanical stimulus control group were light anesthetized and nociceptive mechanical stimulus were applied to the ipsilateral masseter. Pain response was recorded and all the animals were killed 2 hours later. The rats in the other two groups were deep anesthetized and 100 microL 5% formalin was injected into the ipsilateral masseter, killed 2 hours later. The brainstem and cervical spinal cord were processed c-fos and substance P immunoreactivity and data were quantitatively analyzed.</p><p><b>RESULTS</b>Both mechanical and chemical stimulus to the ipsilateral masseter induced increasing neuronal c-fos expression in the trigeminal nucleus and in the cervical spinal dorsal horn in occlusal interference and mechanical stimulus group and occlusal interference and chemical stimulus group (P < 0.05). Following mechanical stimulation to the ipsilateral masseter, substance P expression in the trigeminal nucleus transition zone was increased in occlusal interference and mechanical stimulus group (P < 0.05).</p><p><b>CONCLUSION</b>The central neuronal sensitization in the brainstem may play an important role in the masticatory muscle pain induced by occlusal interference.</p>

Cone beam computed tomography in the diagnosis of temporomandibular joint osteoarthrosis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the clinical use of cone beam dental CT in the diagnosis of temporomandibular joint osteoarthrosis.</p><p><b>METHODS</b>Forty-eight cases diagnosed as temporomandibular joint osteoarthrosis (OA) and disk displacement with or without reduction accompanied by OA changes were included, and a total of 96 joints received both trans-pharyngeal radiography and cone beam CT (CBCT) examination. The detectable rate for OA radiographic changes was compared between the two examinations.</p><p><b>RESULTS</b>The radiographic appearances of osteoarthrotic condyle included six types: loss of the lamina dura density of condyle surface (type I), destructive and erosive bone changes (type II), flattening of the articular surface (type III), sclerosis (type IV), osteophytes (type V), and false cyst change (type VI). The detectable ratio of CBCT for all types of osteoarthrosis was 65.63%, 37.50%, 27.08%, 31.25%, 28.13%, 1.04%, respectively, and the detectable ratio of trans-pharyngeal radiographs was 52.08%, 19.79%, 32.29%, 23.96%, 12.50%, 2.08% respectively. Intraobserver and interobserver reproducibility for type I and type II was in good agreement with both the trans-pharyngeal radiographs and CBCT, Kappa > 0.60.</p><p><b>CONCLUSIONS</b>CBCT had higher detectable rates for pathological changes of osteoarthrosis, and could show the exact location, size, and the types of pathological changes. CBCT may be used as a measure in evaluating disease severity and progression, and in clinical trials of disease treatment.</p>

The relationship between symptoms and signs of temporomandibular disorders and the patients' quality of life / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To analyze the relationship between symptoms and signs of temporomandibular disorders (TMD) and the patients' quality of life (QOL).</p><p><b>METHODS</b>A total of 492 TMD patients were included in this study. The clinical examination results were recorded using Fricton index of temporomandibular joint function. "Visual analog scale (VAS) evaluation of QOL disturbance" was designed to quantitate patients' QOL, to evaluate the degree that the patients QOL was affected.</p><p><b>RESULTS</b>Chewing, daily life and emotion among all 8 items of QOL were frequently affected by TMD, and joint clicking had the least influence on QOL. Intermittent closed lock had more severe interference with QOL than joint clicking only. Severe and moderate pain or limited mouth opening affected the QOL more severely than mild pain or mild limited mouth opening. The simple linear relationship between Fricton index and patients' QOL was poor (r < 0.4).</p><p><b>CONCLUSIONS</b>Pain is the most frequently seen symptom in TMD. TMD could affect patients' QOL, including both physical and social-psychological functions. The results suggest that the patients' QOL as well as TMD symptoms and signs should be considered in the management of TMD.</p>

Comparative study on the clinical appearances between acute and chronic anterior disc displacement without reduction / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To compare the clinical appearances of TMD patients between acute and chronic anterior disc displacement without reduction.</p><p><b>METHODS</b>Successive one hundred TMD patients with fully recorded documents diagnosed as anterior disc displacement without reduction (ADDw/oR) were included, 45 acute and 55 chronic ADDw/oR patients. Clinical appearances including signs and symptoms, maximal mouth opening, Fricton's craniomandibular index, condylar bone changes on radiograms, findings on arthrograms and MRI were compared.</p><p><b>RESULTS</b>The main reason for asking treatment was joint pain in chronic, instead of limited mouth opening in acute patients. Clinical symptoms such as pain and limited mandibular movement showed improvement in chronic patients. Fricton's joint dysfunction index was higher in acute than in chronic patients, but muscle palpation index was higher in chronic than in acute patients, but Fricton's craniomandibular index was not significantly different between chronic and acute patients. The destructive bone changes of condyle on radiograms, the damage of stretched disc attachment on arthrograms and the morphological deformed disc on MRI were more frequently found in chronic than in acute patients.</p><p><b>CONCLUSIONS</b>In acute patients there is a great likelihood that tissues are healthy and not morphologically changed, we suggest that early and efficacious intervention should be made to reposition the anterior displaced disc that may block the progress of pathological impairment to both the disc and the condyle of TMJ.</p>

Hemimasticatory muscle spasm: an electromyogram analysis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the usefulness of electromyogram (EMG) in the diagnosis of the patients with hemimasticatory spasm (HMS).</p><p><b>METHODS</b>Four cases with HMS were reported. All the 4 patients were undertaken needle and surface electrode EMG examination.</p><p><b>RESULTS</b>Needle electrode EMG of the 4 patients with HMS showed grouped potentials synchronously with the onset of the spasm, which indicated abnormal excitatory electrical activities of the trigeminal nerve resulting in involuntary masticatory muscle movements.</p><p><b>CONCLUSION</b>It is very important to use EMG for the diagnosis of HMS.</p>

Temporomandibular joint disc displacement: diagnosis by arthrography with dental volumetric computerized tomography / 中华口腔医学杂志

<p><b>OBJECTIVE</b>Temporomandibular joint sideways and rotational disc displacement was assessed by arthrography with dental volumetric computerized tomography.</p><p><b>METHODS</b>The study was conducted retrospectively on 119 joints of 109 patients (87 females, 22 males, mean age 31.1 years), who had undergone arthrography with dental volumetric CT in the sagittal and coronal planes. The disc displacements were subdivided into 5 types; condylar abnormalities were subdivided into 4 types.</p><p><b>RESULTS</b>Complete anterior disc displacement was the commonest (70.6%) and medial the rarest (0.8%); anterolateral and anteromedial displacements were 18.5% and 10.1% respectively. The types of disc displacements were not correlated with bone lesions. A higher prevalences of bone lesions were found in the lateral poles of condyles.</p><p><b>CONCLUSIONS</b>Arthrography using dental volume CT can be taken in the sagittal and coronal planes, so the sideways and rotational disc displacements, perforations and bone lesions can be evaluated. It's superior to conventional arthrography.</p>