Pain is the most common complaint in the dental field and may have a significant impact on the patients' quality of life. However, objective pain assessment is sometimes difficult, and medical and dental clinicians may encounter cases of pain in the head and neck region, making it difficult to establish differential diagnoses. This study aimed to review acute pain in clinical dentistry at each phase of dental procedures and discuss the current status and issues in the development of acute dental pain assessment methods in the future. Acute pain in clinical dentistry may differ in nature and modifying conditions of pain at each stage: before dental procedures, while visiting dentists, and during and after dental procedures. They are related to actual or potential tissue damage, and may be modified and aided by personal experiences, including psychological and social factors. With respect to the aging and multinational population and pandemic of infectious diseases, significant breakthroughs in the development of new pain scales without verbal descriptions are desirable. Furthermore, it is expected that a new pain scale that can be applied to acute pain in the head and neck regions, including the oral cavity, will be developed.

Periodontitis is one of the most common chronic oral inflammatory conditions worldwide and is associated with a risk of developing oral squamous cell carcinoma (OSCC). Porphyromonas gingivalis is a major pathogen in periodontitis, and its lipopolysaccharide (LPS) promotes the expression of cyclooxygenase-2 (COX-2) in OSCC both in vivo and in vitro. Celecoxib is a selective COX-2 inhibitor; however, its antitumor effects on P. gingivalis LPS-stimulated OSCC and the underlying molecular mechanism remain unclear. To elucidate the association between periodontitis and OSCC, the effect of P. gingivalis-derived LPS on OSCC cell proliferation was examined both in vitro and in vivo in the present study. The expression levels of COX-2 and p53 in OSCC cells with/without celecoxib treatment were determined via western blotting. The therapeutic potential of celecoxib in LPS-stimulated OSCC was evaluated by staining for Ki-67 and p21, as well as with terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling staining. LPS treatment significantly increased OSCC cell proliferation in vitro, and celecoxib significantly inhibited cell proliferation with/without LPS treatment. Celecoxib treatment of OSCC cells downregulated the protein expression levels of COX-2 compared with untreated cells, but there was little change in p53 expression. In the mouse xenograft model, oral administration of celecoxib significantly suppressed tumor growth, reduced the expression of Ki-67, increased the apoptosis index and induced p21 expression with/without LPS treatment. The results from the present study demonstrate that P. gingivalis' LPS can stimulate tumor growth by interacting with OSCC cells. In conclusion, these results suggest that celecoxib could be used for the effective prevention and treatment of LPS-stimulated OSCC.

Ameloblastic carcinoma (AC) is a malignant form of ameloblastoma and an extremely rare odontogenic tumor.Herein, we report a case of AC of the maxilla. A 62-year-old woman presented to a dental clinic with tenderness of the right cheek. A panoramic radiograph showed a radiolucency in the right maxilla, and she was referred to another hospital. With a provisional diagnosis of a benign lesion, she underwent surgical removal of the maxillary mass, following which a pathological diagnosis of AC was made. Subsequently, she was referred to our department for further treatment, and she underwent partial maxillectomy. She remained disease-free at 3-year follow-up. We performed a literature review of AC cases reported in the last decade. Of 36 AC cases, 63.9％ were clinically diagnosed as benign lesions ; among them, 52.2％ cases were clinically diagnosed as ameloblastoma. Conversely, 92.6％ cases were diagnosed as malignant lesions on biopsy ; among them, 76％ cases were pathologically diagnosed as AC. These findings suggest that clinical and imaging findings may complicate the differentiation of AC from ameloblastoma ; however, performing a biopsy can help obtain a correct diagnosis, leading to appropriate treatment planning.

Accidental ingestion of dental prostheses requires immediate emergency action. The authors report a case of accidental ingestion of a dental prosthesis in a patient with a disorder of consciousness. The accidental ingestion was diagnosed by imaging examination, and the location of the dental prosthesis was explored under general anesthesia according to the preoperative examination images. However, no dental prosthesis was found in the hypopharyngeal region. The operators found a radiopaque region in the nasopharynx that was suspicious of a dental prosthesis by X-ray examination of the head and neck region. According to the X-ray examination, the dental prosthesis was removed from the nasopharynx. The patient’s postoperative course was uneventful. Postural change for cases of accidental ingestion of dental prostheses may be a simple and important lifesaving step in addition to traditional methods.

The mandible is commonly disturbed by medication-related osteonecrosis of the jaws (MRONJ), and preservation of inferior alveolar nerve (IAN) function is critical after surgery. A piezoelectric device is an ultrasound instrument that can remove the bone without soft tissue damage. We evaluated the usefulness of the piezoelectric device for the removal of a sequestrum involving the IAN in MRONJ patients with comparison to a conventional device such as rotary burs. Piezoelectric device group (n=12) and conventional device group (n=8) were compared for age, sex, disease, medication, cause, stage, operation time, hospitalization, prognosis, and subjective neurological dysfunction of the mental region with a question. In the piezoelectric device group, the neurological function was also assessed objectively with neurosensory testing. Both groups were similar in age distributions and MRONJ stage. The piezoelectric device group tended to be associated with female patients with osteoporosis and those receiving oral bisphosphonates; however, no significant differences. A comparison of the clinical outcomes showed a tendency of the reduction in the operation time and hospitalization period in the piezoelectric device group; however, no significant difference. Almost good prognosis was obtained in both groups. Subjective neurosensory dysfunction of the mental region was observed in both groups at 1 week postoperation, but the incident rate was lower in the piezoelectric device group. At 8 weeks postoperation, no patients in the piezoelectric device group showed dysfunction while 2 patients in the conventional device group showed dysfunction. In the piezoelectric device group, objective neurosensory tests of the IAN showed 2 patients of dysfunction at 1 week postoperation, but improved within 4 weeks postoperation. Piezoelectric surgery safely removed the sequestrum adjacent to the IAN with good prognosis in MRONJ patients. Our results indicate that piezoelectric surgery may be helpful in shortening the operation and hospitalization time, and reducing the risk of nerve injury.