Objective The temporomandibular joint (TMJ) significantly influences the outcomes of orthognathic surgery, particularly in patients with skeletal class II deformities. These patients often exhibit symptoms such as joint noise, pain, and limited mouth opening. Although magnetic resonance imaging (MRI) is commonly used to evaluate TMJ disorders due to its effectiveness in assessing the position of the articular disc, it has limitations in detecting disc perforations. This study aimed to investigate the relationship between preoperative MRI findings and arthroscopic observations in patients with skeletal class II deformities, focusing on identifying disc perforations. Methods We examined 94 TMJs in 47 patients scheduled for orthognathic surgery. Preoperative MRI was performed to assess disc position, and arthroscopic examination was conducted to confirm intra-articular abnormalities, including disc perforations. The correlation between MRI findings and arthroscopic observations was statistically analyzed. Results MRI results showed that 69.1% of joints had anterior disc displacement without reduction (ADDwo/R). Arthroscopic examination revealed disc perforation in 33.3% of the joints. Statistical analysis demonstrated a significant correlation (p = 0.0036) between MRI-detected ADDwo/R and disc perforation observed during arthroscopy. Specifically, 30.1% of joints with ADDwo/R were found to have disc perforation. Additionally, arthroscopy revealed synovial hyperemia in many cases, suggesting that synovial inflammation may precede disc perforation. Conclusions These findings suggest that TMJ arthroscopy is valuable in the preoperative evaluation of patients with skeletal class II deformities, as it can reveal critical internal abnormalities that may be missed by MRI alone. The high frequency of disc perforation observed in these patients may contribute to the postoperative relapse commonly seen in skeletal class II cases. This study highlights the importance of comprehensive preoperative TMJ evaluation, including arthroscopy, to improve surgical outcomes.

OBJECTIVE:Compressive mechanical stress was applied to the temporomandibular joints (TMJ) affected by antigen-induced arthritis to assess the etiological factors of idiopathic condylar resorption. METHODS:Following ovariectomy in 27 female rabbits, 12 received ovalbumin (OVA), 12 received phosphate-buffered saline, and three formed the control group. Each treated rabbit underwent an osteotomy, and a custom device was employed for one week postoperatively, with the length increased by 0.25 mm every 12 h to provide compressive mechanical stress to the TMJ. Thereafter, samples were obtained from the treated groups, subjected to histological staining and immunohistochemistry, and examined using micro-computed tomography. RESULTS:At each examination, the OVA group showed a greater area and depth of bone resorption, with bone resorption continuing for three weeks following distraction. Additionally, subcondylar bone resorption was noted significantly earlier and had a greater prevalence in the OVA group and greater numbers of tartrate-resistant acid phosphatase-positive cells. Immunostaining for metalloproteinase (MMP)-3 and MMP-13 of the anterior condylar head in the OVA group after two and three weeks revealed high levels of both proteins from the surface to the deep cartilage layer. CONCLUSION:Therefore, coexisting TMJ pathology factors, such as antigen-induced arthritis, promote a significantly greater amount of condylar head anterior surface bone resorption.

The mental nerve block is one of the peripheral branches of the trigeminal nerve block used to treat idiopathic trigeminal neuralgia. Complications of mental nerve block include nerve injury, intravascular injection, and hematoma; however, reports describing oral ulceration are rare. A case of oral ulceration caused by mental nerve block is reported. An 84-year-old female was referred to the authors' department with the chief complaint of oral ulceration in the left mandible. She had a medical history of idiopathic trigeminal neuralgia and was regularly treated with mental nerve block under local anesthesia in the anesthesiology department of the authors' hospital. It was suspected that mental nerve block was the cause of the oral ulceration because the patient was treated immediately before ulceration occurred. The mental nerve block was discontinued after her first visit and the oral ulceration disappeared two months later. Subsequently, oral ulceration did not recur, although the mental nerve block was resumed.

Background: Osteochondromas of the mandibular condyle show facial asymmetry and malocclusion. Because condylar osteochondromas are generally resected in a preauricular approach with risks of facial nerve injury and visible scar, the authors report endoscopically assisted intraoral resection of osteochondroma of the mandibular condyle with a piezoelectric surgical device.Case presentation: A 38-year-old woman presented with malocclusion and facial asymmetry caused by deviation of the chin to the left. Computed tomography showed a hyperdense, well-circumscribed mass arising from the medial aspect of the right mandibular condyle with resorption of the skull base. The patient underwent an endoscopically-assisted intraoral condylectomy with a piezoelectric surgical device. The postoperative course was uneventful without trismus, malocclusion, or facial asymmetry, and there was no recurrence 4 years after surgery.Conclusion:Endoscopically assisted intraoral resection of osteochondroma of the mandibular condyle with a piezoelectric surgical device is a minimally invasive and safe surgery.

We investigated the incidence of disc damage and disc perforation in patients with dentofacial deformities and attempted to clarify the relationship with inflammatory cytokines in synovial fluid.

Ameloblastic fibro-odontoma (AFO) is an uncommon odontogenic tumor consisting of both odontogenic epithelium and odontogenic ectodermal mesenchymal tissues. Two pediatric cases of AFO are reported.Case 1: A 3-year-old girl was referred to our hospital for treatment of a radiolucent lesion in the right maxillary region. Radiographic examination showed a well-defined radiolucency containing a large number of calcifica-tions. The clinical diagnosis was AFO, and surgical extraction was performed with the patient under general anesthesia. At the 48-month follow-up evaluation, there was no evidence of recurrence.Case 2: A 6-year-old girl was referred to our hospital for treatment of a radiolucent lesion in the left mandibular region. Radiographic examination showed a well-defined radiolucency containing a large number of calcifica-tions. The clinical diagnosis was AFO, and surgical extraction was performed with the patient under general anesthesia. At the 12-month follow-up evaluation, there was no evidence of recurrence.

Background: On the mucosa, the retention of drugs including magnesium oxide for laxative sometimes causes drug-induced contact mucositis. Case presentation: A 72-year-old man presented with discomfort in the oral floor. He suffered from paralysis on the right side of his body. After his meal, it was observed magnesium oxide were retained on the right side of the oral floor. After our instruction of taking drugs with food thickening agents, his mucosa became normal soon. Conclusion: We realized that the supervising of taking medicine in the right way is important for the patients such as oral dysphagia especially with elderly and paralysis.

Both Achilles and masticatory muscle tendons are large load-bearing structures, and excessive mechanical loading leads to hypertrophic changes in these tendons. In the maxillofacial region, hyperplasia of the masticatory muscle tendons and aponeurosis affect muscle extensibility resulting in limited mouth opening. Although gene expression profiles of Achilles and patellar tendons under mechanical strain are well investigated in rodents, the gene expression profile of the masticatory muscle tendons remains unexplored. Herein, we examined the gene expression pattern of masticatory muscle tendons and compared it with that of Achilles tendons under tensile strain conditions in the Japanese macaque Macaca fuscata. Primary tenocytes isolated from the masticatory muscle tendons (temporal tendon and masseter aponeurosis) and Achilles tendons were mechanically loaded using the tensile force and gene expression was analyzed using the next-generation sequencing. In tendons exposed to tensile strain, we identified 1076 differentially expressed genes with a false discovery rate (FDR) < 10−10. To identify genes that are differentially expressed in temporal tendon and masseter aponeurosis, an FDR of < 10−10 was used, whereas the FDR for Achilles tendons was set at > 0.05. Results showed that 147 genes are differentially expressed between temporal tendons and masseter aponeurosis, out of which, 125 human orthologs were identified using the Ensemble database. Eight of these orthologs were related to tendons and among them the expression of the glycoprotein nmb and sphingosine kinase 1 was increased in temporal tendons and masseter aponeurosis following exposure to tensile strain. Moreover, the expression of tubulin beta 3 class III, which promotes cell cycle progression, and septin 9, which promotes cytoskeletal rearrangements, were decreased in stretched Achilles tendon cells and their expression was increased in stretched masseter aponeurosis and temporal tendon cells. In conclusion, cyclic strain differentially affects gene expression in Achilles tendons and tendons of the masticatory muscles.

Objectives: Psychological stress affects bone metabolism. The elucidation of the effect of stress on bone metabolism have become an urgent issue. We previously demonstrated that the hypothalamic-pituitary-adrenal axis is involved in bone metabolism through melanocortin 2 receptor (MC2R). A short-term ascorbic acid treatment for mesenchymal stem cells derived from calvariae of MC2R deficient mice slightly promotes bone gamma-carboxyglutamate protein mRNA expression which is associated with osteoblast differentiation. Herein, we examine whether a long-term ascorbic acid with b-glycerophosphate treatment promotes osteoblast differentiation in the absence of MC2R.Methods: Alizarin red staining, reverse-transcription polymerase chain reaction, quantitative reverse-transcription polymerase chain reaction, and cell proliferation assay were performed.Results: We provide the evidence that a long-term ascorbic acid treatment significantly promotes calcification and upregulates the expression of vascular endothelial growth factor (VEGF)-D but not VEGF-A. Moreover, we found that adrenocorticotropic hormone enhanced VEGF-D mRNA expression in the absence of MC2R and MC2R deficient mice possess melanocortin 3 receptor.Conclusions: Collectively, VEGF-D upregulation may be induced through ACTH-melanocortin 3 receptor signaling during osteoblast differentiation.

BACKGROUND/AIM:Bone and nerve reconstruction is crucial for treating various diseases of the oral and maxillofacial region. However, the relationship between bone and nervous system has not yet been fully elucidated. Therefore, we aimed to examine the interaction between osteoblasts and neuronal cells in contact co-culture.MATERIAL AND METHODS:Osteoblasts and sympathetic neuronal cells were grown in contact co-culture. Microscopic observation, a mineralization assay, immunofluorescence staining, and DNA microarray analysis were performed.RESULTS:Microscopic observation revealed morphological changes in the osteoblasts that were cocultured with sympathetic neuronal cells. Contact co-culture enhanced osteoblast calcification and upregulated a neuronal marker. Not only osteoblast differentiation signals, but also neuronal signals were increased in murine osteoblasts that were co-cultured with rat sympathetic neuronal cells. We also found that not only rat neuron differentiation signals, but also osteoblast differentiation signals were increased in rat sympathetic neuronal cells that were co-cultured with murine osteoblasts.CONCLUSION:In the contact co-culture with osteoblasts and sympathetic neuronal cells, the sympathetic neuronal cells promoted osteoblast differentiation, and the osteoblasts promoted neuron differentiation.

Osteoma is a lesion that comprises growth of mature bone tissue. Peripheral osteoma can occur in the mandible at the inner or outer edge of the mandibular angle, the lower edge of the chin, or the lingual aspect of the molar region. We report a case of osteoma that arose on the medial and lateral aspects of the right mandibular angle.

Background: Necrotizing periodontitis (NP) is a reactive and destructive inflammatory process that occurs in response to bacterial infection. Predisposing factors such as compromised host immune responses contribute significantly to NP pathogenesis. NP occasionally progresses to a more advanced and life-threatening state. Case presentation: A 73-year-old man in need of nursing care visited our dental clinic with severe gingival pain and intraoral bleeding. He had a disability and was immunocompromised because his medical history included cerebral infarction and type 2 diabetes mellitus. He was diagnosed with NP based on his typical symptoms, such as prominent bleeding and suppurative discharge from the gingiva, in addition to crater-shaped ulcerations of the interdental papillae. To improve daily oral hygiene, periodontists, dentists, and dental hygienists educated care workers and other staff at the nursing home on appropriate oral cleansing, including brushing three times a day using the Bass technique. Basic periodontal therapy, including whole-mouth scaling and debridement of the root surfaces using hand and ultrasonic instruments, was also performed. After this basic treatment of NP, we extracted the hopeless teeth. Currently, dentists visit the patient fortnightly to manage his oral hygiene. To date, good oral health has been maintained.

(1) Background: Chronic psychosocial stress can lead to oral dysesthesia with tongue pain. We examined whether psychosocial stress causes orofacial pain, and analyzed the comprehensive gene expression patterns of circulating cells and transient receptor potential ankyrin 1 (TRPA1) expression in trigeminal ganglion (TG) neurons in a mouse model of psychosocial stress. (2) Methods: Mice were divided into two groups: one group was kept in confrontational housing, and the other group was kept in single housing. Blood, adrenal gland, and tongue were collected. The head withdrawal threshold (HWT) of mechanical stimulation to the whisker pad skin was measured. TRPA1-positive TG neurons were immunohistochemically examined. DNA microarray analysis and quantitative reverse transcription polymerase chain reaction analysis were performed. (3) Results: The HWT was significantly lower in mice under the psychosocial stress condition compared to non-stressed mice. In stress-loaded mice, the number of TRPA1-positive TG neurons was significantly increased. Moreover, we showed that trace amine-associated receptor 7f expression was upregulated in circulating cells in blood and downregulated in the tongue. (4) Conclusions: Our results indicated that chronic psychosocial stress induced the orofacial mechanical allodynia through enhancement of TRPA1 expression in TG neurons with changes in the levels of trace amine-associated receptor 7f.

Background/Aim: Masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) is a disease associated with a mouth opening limitation. Here, we conducted a bioinformatics analysis to examine gene expression patterns in patients with MMTAH in comparison to those with facial deformity (FD). Materials and Methods: Seven MMTAH patients and three FD patients were recruited. We conducted RNA sequencing analysis, quantitative reverse transcription polymerase chain reaction and immunoblot analysis. Results: Of the identified 19,767 mapped read tags that showed clear differential expression, 2,471 genes were significantly up-regulated and 2,849 genes were significantly down-regulated in patients with MMTAH compared to those in patients with FD. Among the up-regulated genes, ten genes were significantly increased. The distribution of up-regulated and down-regulated genes at different ages tended to be similar. Moreover, the protein levels of Ankyrin Repeat Domain 2, Troponin T1 and myosin heavy chain 7, which are associated with slow twitch fibers and mechanical loading, were strongly expressed in patients with MMTAH compared to those in patients with FD. Conclusion: The gene expression pattern in MMTAH patients was similar regardless of age. As the transition of fast-to-slow twitch in the skeletal muscle is induced by mechanical loading, and up-regulation of slow twitch molecules was observed in MMTAH patients, mechanical loading is suggested to be implicated in MMTAH.

Hemophilia A is a hereditary disorder caused by missing factor VIII. When planning tooth extraction in patients with hemophilia A, attention should be paid to the risk of postoperative bleeding. We report two cases of patients with mild hemophilia A who underwent teeth extraction treated with Turoctocog alfa with close monitoring of coagulation factor VIII activity for 2 weeks. Notwithstanding the adequate replacement therapy with coagulation factor VIII and auxiliary hemostasis, postoperative bleeding was still observed more than once. Adequate explanation of the possibility of postoperative bleeding prior to the treatment to the patients is crucial in such cases. The development of new guidelines for teeth extraction of hemophilia A should be considered.

A 57-year-old male visited the hospital’s internal medicine department with a chief complaint of cognitive impairment for the past month. His Mini-Mental State Examination (MMSE) score was 23 points, exhibiting mild cognitive impairment. Brain magnetic resonance imaging (MRI) revealed no abnormalities; however, positive anti-SSA and anti-SSB antibodies were detected via bloodwork. To assess the patient for Sjögren’s syndrome (SS), the internal medicine department referred the patient to our department. Lip biopsy detected infiltrates of more than 50 lymphocytes surrounding the duct of the minor salivary gland. Furthermore, the patient’s brain single-photon emission computed tomography (SPECT) revealed a mild blood flow reduction within the frontal lobe, parietal lobe, and posterior cingulate gyrus on the right side. Findings from the patient’s bloodwork and histopathological examination led to a diagnosis of SS. Other autoimmune diseases did not complicated the diagnosis, and the diagnosis was primary Sjögren’s syndrome (pSS) accompanied by autoimmune encephalitis. After hospitalization by internal medicine physicians, pulse steroid therapy was initiated, and the patient displayed cognitive improvement, with an improvement in the MMSE score to 27 points.

The present study explored whether the dopamine 2-like receptor agonist, ropinirole, a drug used for treating Parkinson's disease, suppresses neutrophilic inflammation and alveolar bone loss in an experimental rat model of periodontitis. Periodontitis is a neutrophilic inflammatory disease caused by periodontal pathogens. An excessive T helper (Th)17 immune response is involved in the progression of periodontitis, and interleukin (IL)-17 promotes the exacerbation of inflammation and alveolar bone destruction. Recent evidence has suggested that dopamine signaling plays a key role in Th17 cell differentiation, and that dopamine 2-like receptor agonists suppress cytokine production from Th17 cells. We previously demonstrated that tannic acid, which is a dopamine 2-like receptor agonist, inhibits alveolar bone resorption in an experimental model of periodontitis. The present study used a carrageenan-induced rat model of periodontitis with or without ropinirole. Micro-computed tomography analysis was performed. Cells of the murine gingival epithelial cell line GE1 were stimulated with carrageenan and IL-17A in the presence or absence of ropinirole. The anti-inflammatory effect of ropinirole was analyzed using reverse transcription- quantitative PCR and enzyme-linked immunosorbent assay. Subsequently, in the carrageenan-induced rat model of periodontitis, alveolar bone resorption was observed in the maxillary second molar by micro-computed tomography analysis. Intriguingly, ropinirole suppressed the alveolar bone destruction. The expression levels of C-X-C motif chemokine ligand 1 (CXCL1) and IL-17 receptor A (IL-17RA) in GE1 cells were increased by carrageenan, and CXCL1 expression in GE1 cells was upregulated under IL-17A stimulation. Moreover, ropinirole inhibited CXCL1 and IL-17RA expression in GE1 cells in the presence of IL-17A and carrageenan. Finally, haloperidol promoted CXCL1 expression in GE1 cells in the presence of carrageenan. Overall, these findings suggested that ropinirole suppressed neutrophilic inflammation and alveolar bone destruction in periodontitis by inhibiting CXCL1 expression in gingival epithelial cells through the dopamine 2-like receptor. Thus, ropinirole shows promise as a drug for the treatment of periodontitis.

Impacted mandibular third molar extraction is one of the most frequent procedures performed in the field of oral surgery. Oral surgeons sometimes face cases that cannot be extracted using the conventional procedure because of atypical tooth structure or irregular tooth position in the mandible. Here, we report an unusual impacted third mandibular molar with atypical root form, which was extracted by buccal cortex osteotomy of the mandibular ramus. A 42-year-old Japanese female presented with a complaint of discomfort in the left molar region. Radiographical examination showed an impacted third molar with a mushroom-like root overlapping the mandibular canal. This lesion was radiographically diagnosed as cemental hyperplasia. The tooth could not be extracted using the conventional procedure, and buccal cortex osteotomy was applied. Briefly, bones necessary for extraction were removed once from the mandibular ramus. After extraction, the bony fragment was repositioned in the original position. The patient experienced no postoperative complications such as nerve paralysis, mandibular angle fracture, and infections. Buccal cortex osteotomy is a simple and easy technique to extract impacted mandibular third molars that cannot be extracted by conventional methods.

Dental implant treatment is now becoming a popular treatment option for defective prosthesis.However, there are several potential complications associated with implant treatment, such as infection of the implant, loss of sensation, or cancer secondary to the implant.Loss of sensation caused by implant placement can lead to a significantly lower