Identification and adjustment of experimental occlusal interference using functional magnetic resonance imaging.

BACKGROUND: The purpose of this study was to use functional magnetic resonance imaging (fMRI) to quantify changes in brain activity during experimental occlusal interference. METHODS: Fourteen healthy volunteers performed a rhythmical tapping occlusion task with experimental occlusal interference of the right molar tooth at 0 mm (no occlusion), 0.5 mm, and 0.75 mm. The blood-oxygen-level dependent (BOLD) signal was quantified using statistical parametric mapping and compared between rest periods and task periods. RESULTS: In tapping tasks with experimental occlusal interference of 0.75 mm or 0.5 mm, there was clear activation of the contralateral teeth-related primary sensory cortex and Brodmann's area 46. At 0 and 30 minutes after removal of the experimental occlusal interference, the activation clearly appeared in the bilateral teeth-related primary sensory cortices and Brodmann's area 46. At 60 minutes after the removal of the experimental occlusal interference, the activation of Brodmann's area 46 had disappeared, and only the bilateral teeth-related primary sensory cortices were active. CONCLUSIONS: The present results suggest that adjustments for experimental occlusal interference can be objectively evaluated using fMRI. We expect that this method of evaluating adjustments in occlusal interference, combined with fMRI and the tapping task, could be applied clinically in the future.

Effectiveness of denture space recording method in the prosthetic treatment of edentulous patients.

PURPOSE: To present a clinical rationale for the effectiveness of denture space recording methods for the prosthetic treatment of edentulous patients through a review of the literature. STUDY SELECTION: A total of 3167 studies were extracted from a search of four terms, namely denture space, neutral zone technique, flange technique, and piezography using PubMed and J-STAGE databases. A total of 57 documents that matched the inclusion and exclusion criteria were selected. RESULTS: From the extracted articles, the clinical application of denture space recording methods was found to be effective in edentulous patients with severe ridge resorption. The relationship between the labiolingual and buccolingual pressure in patients with neuromuscular problems or with mandibular or lingual defects differs from those without it, so a stable prosthesis can be easily fabricated by locating the neutral zone using denture space recording methods. CONCLUSION: The literature on denture space recording methods suggests that its application on challenging cases of edentulous patients is useful in providing prostheses with improved retention and stability.

The comparison of two different mandibular positions for oral appliance therapy in patients with obstructive sleep apnea.

BACKGROUND: An oral appliance (OA) can alleviate upper airway obstruction by pulling the mandible forward during sleep. While a large mandibular advancement with an OA decreases the number of apnea and hypopnea events, long-term use may cause side effects, such as toothache, stiffness, and pain in the temporomandibular joint. OBJETIVES: This study aimed to evaluate the effectiveness of different mandibular positions for obstructive sleep apnea (OSA) and determine the optimal therapeutic mandibular position. METHODS: Thirty-two patients (17 males and 15 females) with mild to moderate OSA participated in this prospective study. All patients were randomly allocated to receive a 50% mandibular advancement or a 75% mandibular advancement with an OA. The pre- and posttreatment apnea-hypopnea index (AHI), apnea index (AI), and Epworth Sleepiness Scale (ESS) were compared. Treatment effectiveness and treatment success were compared between groups. RESULTS: AHI improved significantly in both groups, and AI improved significantly in the group with 50% mandibular advancement. No significant improvements in the ESS were observed in either group. There was no significant difference in treatment effectiveness between groups. In the proportion of females and males whose treatment was effective in the two groups, females were significantly greater than males. CONCLUSIONS: For patients with mild to moderate OSA, 50% mandibular advancement is recommended as the initial therapeutic mandibular position. It was suggested that gender differences also affect treatment effectiveness.

Blood flow changes of a superficial temporal artery before and after low-level laser irradiation applied to the temporomandibular joint area.

PURPOSE: The aim of this study was to evaluate the blood flow changes of a superficial temporal artery before and after low-level laser irradiation was applied to the TMJ area of healthy subjects. METHODS: Right TMJ areas of six healthy subjects were irradiated with a CO2 laser. Variation of diameter, blood flow rate, and blood flow volume of the vessel, on both the irradiated side and opposite side, before and after irradiation on the TMJ were evaluated by using a Doppler flowmeter. RESULTS: The diameter and blood flow volume of the vessel after irradiation increased significantly compared to that before irradiation. CONCLUSION: Low-level laser irradiation applied to the right TMJ area caused an expansion of blood vessels and an increase in blood flow volume. The same result on the contralateral side may be caused by the vasodilator reflex via the hypothalamic thermostat.

Assessment of oral appliance for obstructive sleep apnea patients.

Although oral appliances (OAs) have become widely used for the management of obstructive sleep apnea (OSA), side effects of OAs are generally related to poor utilization. The purpose of the present study was to evaluate relationship between utilization and treatment efficacy of a boil-and-bite appliance for OSA patients. A total of 135 patients with OSA who had used an OAs were mailed a questionnaire to determine whether they were currently using the OA. If so, they were asked about OA use, improvement of signs and subjective symptoms, and utilization. Otherwise, they were asked to indicate why and when they quit using the OA. Results of overnight polysomnography (PSG) before and after treatment were reviewed. Of the 48 responding patients, 33 patients were currently using the OA. The most common complication was excessive salivation (n = 11). All indices from PSG excluding arousal index were significantly improved after treatment (p < 0.05). Thirty patients showed improved signs and subjective symptoms. Eight out of 12 subjects (66.7%) were successfully treated, achieving an apnea-hypopnea index (AHI) < 10/h and >50% reduction in apnea-hypopnea index. Of the 15 patients no longer using the OA, the primary reason for quitting was "no treatment effect" (n = 5). No indices from PSG recording differed between before and after treatment in the not-using group. These results suggest that both subjective and objective signs and symptoms improved with use of the OA in the using group. However, no signs and subjective symptoms or indices of sleep quality differed between before and after treatment in the not-using group. Device improvements are needed to achieve better treatment efficacy, and thus improve compliance. The present study evaluated relationship between utilization and treatment efficacy of a boil -and bite appliance for OSA patients. Device improvements are needed to achieve better treatment efficacy, thus improve compliance.

Evaluation of facial thermographic changes before and after low-level laser irradiation.

OBJECTIVE: The aim of the present study was to evaluate the facial thermographic changes before and after low-level laser irradiation applied to the temporomandibular joint in normal subjects. BACKGROUND DATA: Although this therapy has been reported to be effective in the pain management of patients with rheumatoid arthritis and degenerative joint disease, several researchers have stated that this therapy has no effect on pain of myogeneous origin. MATERIALS AND METHODS: Nine healthy subjects underwent irradiation using the continuous wave setting of a CO2 laser with a power output of 1.0 W. The laser tip was positioned 10 cm above the skin over the right TMJ area for 10 min. The actual fluence on the facial surface was 7.64 J/cm2. Variation of the facial temperature was evaluated by using thermography. RESULTS: The facial temperature 10 min after stopping irradiation was higher than that after 10 min of irradiation applied to the opposite side. The warmer area was found not only over the TMJ area but also over the temporal area, forehead area, and eyelid area on both sides. CONCLUSION: These results suggested that low-level laser irradiation had a long-lasting effect on facial cutaneous tissues.

Use of a tongue-pressure measurement system to assist fabrication of palatal augmentation prostheses.

PURPOSE: The purpose of this study was to determine a baseline value of tongue pressure on the palatal region in normal subjects that could then be used to assist in fabrication of a palatal augmentation prosthesis (PAP). MATERIALS AND METHODS: A tongue-pressure measurement system with 36 rubber pressure sensors was constructed for this study. This system was applied to 16 normal subjects, and the tongue pressure on the palatal region was measured when they were swallowing. RESULTS: The maximum tongue pressures seen during swallowing were 85.0 g/cm2 in the early stage, 95.0 g/cm2 in the middle stage, and 93.0 g/cm2 in the late stage. The average maximum tongue pressure throughout swallowing was 91.0 g/cm2. The tongue pressure in the early stage ranged from 3.37 g/cm2 to 8.74 g/cm2. A significant difference was found between the anterior and the posterior regions and between the central and the posterior regions. The value in the middle stage ranged from 5.32 g/cm2 to 10.22 g/cm2. Significant differences were found between the anterior and the posterior regions and between the central and the posterior regions. Values in the late stage ranged from 6.80 g/cm2 to 7.91 g/cm2. CONCLUSION: The average maximum tongue pressure against the palate of approximately 90 g/cm2 suggests that a PAP sufficient for swallowing should be strong enough to withstand this amount of pressure. The device is also useful to check for variations in the tongue contact area during trial of the prosthesis.