Bulletin of Tokyo Dental College最新文献

Porphyromonas gingivalis, a key periodontal pathogen, employs extra-cytoplasmic function (ECF) sigma factors to adapt to the dynamic oral environment and establish chronic infection. Among these, PGN_1740 (SigH) has been implicated in oxidative stress response and iron acquisition, yet its transcriptional regulatory mechanisms remain poorly understood. The aim of this study was to elucidate the functional role of SigH using sigH-deficient mutants. Quantitative reverse transcription-polymerase chain reaction was performed to assess the transcriptional profiles of sigH and its putative target genes, sod and ltp1, throughout the growth of P. gingivalis. Electrophoretic mobility shift assay (EMSA) was conducted to evaluate the direct binding of recombinant SigH to the sod and ltp1 promoter regions. Oxygen sensitivity was also assessed using hydrogen peroxide susceptibility and cell invasion assays. The results of these experiments revealed that sigH transcription peaked during the mid-log and early stationary phases, followed by a significant decline in the late stationary phase. The EMSA analysis demonstrated that rSigH directly binds to the ltp1 promoter, but not to the sod promoter. Notably, the sigH-deficient mutant exhibited increased oxidative stress sensitivity in the hydrogen peroxide susceptibility assay. Furthermore, unlike the wild type, the sigH-deficient mutant was unable to invade telomerase-immortalized gingival keratinocytes. These findings suggest that the ECF sigma factor SigH regulates oxidative stress tolerance via sod, and iron metabolism via ltp1, in P. gingivalis.

More than 700 types of bacteria coexist in the human oral cavity, including motile and non-motile taxa. Fusobacterium nucleatum plays an important role in this environment as a bridge between early- and late-colonizing bacteria. We hypothesized that Treponema denticola, a motile bacterium, receives a non-contact benefit from coexisting F. nucleatum. To evaluate this hypothesis, the growth and gene expression of T. denticola were investigated in an environment where F. nucleatum was present but not in contact with it. The results showed that proliferation of T. denticola increased in this environment, and that this was attenuated by autoinducer-2 (AI-2) inhibitor _D-ribose. The results of RNA-seq and qRT-PCR showed that the presence of F. nucleatum increased the gene expression levels of TDE_0039 and TDE_0040. These findings revealed that proliferation of T. denticola increased via a substance produced by F. nucleatum. Importantly, this phenomenon occurs even without direct contact between the two species. In other words, T. denticola may gain a survival advantage by moving through the oral environment, and F. nucleatum may play a crucial role in facilitating this.

This study explored the association between tooth extraction, dental visit frequency, and blood glucose levels over a 3-year period in middle-aged and older adults using a large health insurance claims database (DeSC, Tokyo, Japan). Data from 31,373 individuals aged 45-70 years who participated in Specified Medical Checkups and Health Guidance between April 2018 and March 2022 were analyzed. Participants were categorized based on the frequency of their annual dental visits and tooth extractions. The primary outcome was high blood glucose level, defined as HbA1c≥6.5%, or fasting plasma glucose level, at ≥126 mg/dl. Individuals who underwent tooth extractions at baseline had lower odds of high blood glucose levels after 3 years, regardless of their baseline glycemic status. Participants with three or more yearly dental visits had lower odds of a high blood glucose level, particularly those with a high baseline blood glucose level and a body mass index ≥25.0 kg/m². These findings suggest an association between regular dental care and improved glycemic control, particularly in individuals with obesity. However, causal relationships cannot be inferred from this study, and further research is required to examine the impact of periodontal treatment and other dental interventions on diabetes management.

This report describes a case of generalized aggressive periodontitis (Stage III, Grade C) requiring periodontal regenerative therapy. The patient was a 35-year-old woman who visited Tokyo Dental College Suidobashi Hospital with the chief complaint of swelling in the maxillary left gingiva. An initial examination revealed 34.5% of sites with a probing depth (PD) of ≥4 mm. The prevalence of sites with bleeding on probing was 29.8%. The plaque control record (PCR) score was 59.8%. Radiographic examination revealed extensive horizontal bone resorption in the maxillary and mandibular molars. Considerable angular bone resorption was observed in teeth #14 and 24. Furcation involvement was observed in teeth #16 and 46. A clinical diagnosis of generalized aggressive periodontitis (Stage III, Grade C) was made, based on which initial periodontal therapy was performed. An improvement was observed in periodontal conditions on re-evaluation. The PCR score was 11.5%. Periodontal surgery was performed for teeth with a residual PD of ≥4 mm. Periodontal regenerative therapy using recombinant human fibroblast growth factor-2 (rhFGF-2) was performed on intrabony defects in #14 and 24. Open flap debridement was performed on #15, 16, 25, and 26. Root separation was performed on #46. Following re-evaluation, an all-ceramic crown was placed on #46, and the patient was placed on supportive periodontal therapy (SPT). During the 1 year of SPT, stable periodontal conditions have been maintained. However, due to the loss of all the secondary molars, the risks of occlusal trauma to the remaining teeth and root surface caries associated with extensive gingival recession following the periodontal treatment remain. Therefore, continued care is necessary to maintain good periodontal conditions.

The WHO Classification of Head and Neck Tumors (2024) defines solitary neurofibromas as benign peripheral nerve sheath tumors comprising a mixture of Schwann cells, perineuronal cells, fibroblasts, and axons. In the orofacial region, such tumors usually occur on the tongue, and only rarely in the lip. This report describes a case of a solitary neurofibroma arising in the lower lip. The patient was a 59-year-old man who was referred to our hospital with a mass on the lower lip. Palpation revealed that it was elastic, hard, painless, and mobile. Magnetic resonance imaging confirmed the presence of a mass. It was identified as a suspected benign tumor and surgical excision conducted under general anesthesia. A diagnosis of solitary neurofibroma was made based on histopathological findings. One and a half years have passed since the surgery, and no recurrence has been noted. Long-term follow-up has been planned.

Deterioration of oral function can impair articulation, making it essential to evaluate tongue movement during articulation training. Previous reports have indicated an improvement in motor speech disorders, such as glossectomy-related glide issues, through rapid speech exercises, suggesting the potential benefits of non-invasive training. This study aimed to investigate the effect of tongue training on oral function using tongue twisters in healthy Japanese-speaking women. The participants performed tongue twisters designed to engage both the tongue tip and root, with data collected at baseline, 1 month, and 7 months. Participants were required to complete sentences involving the repeated use of /ta/ and /ka/ sounds. This training was conducted 5 times per week for 1 month. Oral diadochokinesis (ODK) was used to measure the number of repetitions per second of each sound, while ultrasound imaging captured the vertical motion of the tongue during pronunciation. The ODK test was used to evaluate speed and regularity of articulatory movement, and ultrasound measurement to assess vertical motion dynamics of the tongue during pronunciation of /ta/ and /ka/. The results indicated a significant improvement in the number of repetitions per second for both /ta/ and /ka/ after 1 month of training. This increase in repetition frequency was maintained for /ta/ even after 7 months, whereas /ka/ showed no further increase in repetition frequency beyond the 1-month mark. Despite this, vertical distance of tongue movement decreased significantly for both syllables after 1 and 7 months. This suggests that /ta/ benefited from both increased efficiency and speed, whereas /ka/ prioritized refined motor control over frequency. The complexity of posterior tongue elevation in /ka/ may require greater precision, limiting increase in repetition despite improved efficiency. This study demonstrates that regular tongue-twister training effectively refines oral function in young women, with sustained benefits over time. The simplicity and accessibility of this method make it a promising approach to maintaining and enhancing oral and articulatory function.

Endothelin (ET) is a peptide comprising 21 amino acids, and its G-protein coupled ETA and ETB receptors are expressed in both cancer cells and cancer-associated cells. Cancer cells excessively express ETA and ETB receptors, and mechanical stimulation promotes the growth and migration of these cells. The autocrine and paracrine signaling of ET is involved in several cancer metabolic pathways, but how this is mediated by the ET-axis (ET and its receptors) remains to be clarified. This study investigated ET-axis-mediated autocrine/paracrine communication in rat squamous cell carcinoma (SCC) in response to direct mechanical stimulation of such cells. Intracellular free Ca²⁺ concentration ([Ca²⁺]_i) was determined using fura-2/AM from a rat SCC cell line (SCC-158). Direct mechanical stimulation of the SCC-158 cells using glass micropipettes to compress the cell membrane to 8 μm for 4 sec induced a transient increase in [Ca²⁺]_i. This increase was also observed in the neighboring cells of the stimulated SCC-158 cells. Treatment with 10 μM Gd³⁺ or 1 μM GsMTx4 almost completely inhibited the mechanical stimulation-induced increase in [Ca²⁺]_i in the SCC-158 cells. Application of 1 μM BQ-123 (an ETA receptor antagonist) inhibited the increase in [Ca²⁺]_i in the stimulated SCC-158 and neighboring cells, whereas that of BQ-788 (an ETB receptor antagonist) had no such effect. These findings suggest that rat SCC cells express the Piezo1 channel. Activation of the Piezo1 channel induced endothelin release from the mechanically stimulated SCC-158 cells. Released ET activated ETA receptors in neighboring SCC-158 cells. These findings also suggest that intercellular paracrine communication among SCC-158 cells through ET signaling plays an important role in the development and metabolism of SCC cells.

Congenital muscular dystrophy (MD) is characterized by progressive muscle weakness. Such patients often present distinctive facial features characterized by excessive vertical growth due to increased muscle breakdown in the perioral muscles such as the masticatory and facial muscles, often resulting in skeletal open bite. Orthognathic treatment is one option for improving the maxillofacial morphology and malocclusion in such patients. However, it is often too risky to apply general anesthesia in such cases due to systemic myofunctional deterioration. Therefore, in many instances, the only option is to rely on orthodontic treatment alone to improve malocclusion. Furthermore, there are few reports on changes following orthodontic treatment in congenital MD patients, and many matters remain unclear regarding long-term occlusal stability. The present case was a girl aged 9 years and 3 months at the initial visit. Her chief complaint was masticatory dysfunction and articulation disorder due to open bite. The first phase of treatment delivered expansion of the upper and lower dental arches and myofunctional therapy prior to transition to the second phase. At the start of the second phase of treatment, the patient was aged 15 years and 9 months. It was determined that orthognathic treatment including surgical invasion would be too risky due general problems related to muscular function. This report describes a case of skeletal open bite due to congenital MD in which an orthodontic approach alone was adopted as camouflage treatment involving extraction of the maxillary left and right second deciduous molars and mandibular left and right first premolars. The post-treatment stability of the resulting occlusion is also described.

Maxillary sinus floor elevation is an option in cases where bone volume in the maxillary molar region is clearly insufficient to allow implant therapy. However, few studies have reported long-term observation of change in bone volume in the same case over a period of 10 or more years. This report describes a case of implant placement following maxillary sinus floor elevation using iliac bone with long-term monitoring of changes in peri-implant bone volume. The patient was a 58-year-old man who visited our clinic in April 2008 with the chief complaint of chewing problems due to missing teeth. The maxillary sinus floor bone had thinned on both sides, and bilateral maxillary sinus floor elevation using an iliac bone graft was therefore planned. In September 2008, trabecular bone containing bone marrow was harvested from the left side of the ilium, and bilateral maxillary sinus floor elevation was carried out with the patient under general anesthesia. After bone healing for approximately 6 months, a total of eight implants were placed in the maxilla under intravenous sedation in March and April 2009. A telescopic-retained implant-supported fixed bridge was attached as the final superstructure in April 2010. Regarding change in bone volume in the elevated maxillary sinus floor, a reduction in bone height was seen during the period between maxillary sinus floor elevation to implant placement. Following implant placement, however, there was no obvious decrease in bone volume, which has remained stable for 10 years following fitting of the superstructure. Maxillary sinus floor elevation with autologous iliac bone graft has thus shown long-term stability in bone volume over more than 10 years following the procedure. Rigorous follow-up of change in bone volume at the engraftment site is still needed, however.

This report describes a case of periodontitis treated with periodontal surgery incorporating autogenous bone graft and recombinant human fibroblast growth factor (rhFGF) -2. The patient was a 49-year-old woman who visited the Tokyo Dental College Suidobashi Hospital with the chief complaint of swelling in the maxillary right gingiva. Tooth #37 had been extracted 12 years earlier. An initial examination revealed 33.9% of sites with a probing depth (PD) of ≥4 mm. The prevalence of sites with bleeding on probing was 35.2%. The plaque control record (PCR) score was 51.9%. Radiographic examination revealed angular bone resorption in tooth #16. Horizontal adsorption was also observed in other areas. A clinical diagnosis of generalized chronic periodontitis (Stage III Grade C) was made and periodontal therapy initiated. An improvement was observed in periodontal conditions at re-evaluation, with her PCR score decreasing to 15.7%. Periodontal surgery was performed for teeth with a residual PD ≥4 mm. Periodontal regenerative therapy using autogenous bone graft and rhFGF-2 were performed for an intrabony defect in #16. Open flap debridement was performed on #17, 35, and 36. Following evaluation, oral function was restored using a hard resin facing metal crown for #12 and CAD/CAM resin crowns for #14, 15, and 24. The patient was then placed on supportive periodontal therapy. The results showed that periodontal regenerative therapy with autogenous bone graft and rhFGF-2 yielded stable periodontal conditions, which facilitated a favorable level of plaque control.