Kentaro Okuno

The effect of oral appliances that advanced the mandible forward and limited mouth opening in patients with obstructive sleep apnea: A systematic review and meta‐analysis of randomised controlled trials

Oral appliances (OAs) have demonstrated efficacy in treating obstructive sleep apnea (OSA), but many different OA devices are available. The Japanese Academy of Dental Sleep Medicine supported the use of OAs that advanced the mandible forward and limited mouth opening and suggested an evaluation of their effects in comparison with untreated or CPAP. A systematic search was undertaken in 16 April 2012. The outcome measures of interest were as follows: Apnea Hypopnea Index (AHI), lowest SpO2 , arousal index, Epworth Sleepiness Scale (ESS), the SF-36 Health Survey. We performed this meta-analysis using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. Five studies remained eligible after applying the exclusion criteria. Comparing OA and control appliance, OA significantly reduced the weighted mean difference (WMD) in both AHI and the arousal index (favouring OA, AHI: -7.05 events h(-1) ; 95% CI, -12.07 to -2.03; P = 0.006, arousal index: -6.95 events h(-1) ; 95% CI, -11.75 to -2.15; P = 0.005). OAs were significantly less effective at reducing the WMD in AHI and improving lowest SpO2 and SF-36 than CPAP, (favouring OA, AHI: 6.11 events h(-1) ; 95% CI, 3.24 to 8.98; P = 0.0001, lowest SpO2 : -2.52%; 95% CI, -4.81 to -0.23; P = 0.03, SF-36: -1.80; 95% CI, -3.17 to -042; P = 0.01). Apnea Hypopnea Index and arousal index were significantly improved by OA relative to the untreated disease. Apnea Hypopnea Index, lowest SpO2 and SF-36 were significantly better with CPAP than with OA. The results of this study suggested that OAs improve OSA compared with untreated. CPAP appears to be more effective in improving OSA than OAs.

Effects of the bolus volume on hyoid movements in normal individuals

The hyoid bone moves during swallowing due to contraction of suprahyoid muscles, which are critical components of normal swallowing function. It has been reported that the muscle force and shortening velocity decline gradually with age. Reduced hyoid velocities may delay the sealing of the laryngeal vestibule and opening of the cricopharyngeal muscle. We hypothesised that the hyoid velocity could be a factor influencing aspiration. This study evaluated effects of bolus volume changes on the hyoid distance and velocity in normal swallowing. The subjects were 21 healthy young adults. Lateral projection videofluorography was recorded while each subject swallowed 2·5, 5·0, 10 and 20 mL of liquid barium. We evaluated the maximum hyoid distance (Max d), anterior and superior distance (Max ad, Max sd). And, we evaluated the maximum velocity (Max v), anterior and superior velocity (Max av, Max sv). Two-way anova test revealed that Max d, Max ad and Max sd for different bolus volumes are not significantly different. But, two-way anova test showed statistically significant difference in Max v, Max av and Max sv among different bolus volume (P < 0·01). Tukeys test showed that there are significant differences in Max v between 2·5 and 20 mL, 5·0 and 20 mL, 10 and 20 mL, and 2·5 and 10 mL swallowing. And, Tukeys test showed significant differences in Max av and Max sv between 2·5 and 20 mL, 5·0 and 20 mL, and 10 and 20 mL swallowing. It is possible that a larger bolus volume requires greater maximum hyoid velocity. We plan to study hyoid velocity in elderly subjects and in those with dysphagia.

Erratum to: Videoendoscopic diagnosis for predicting the response to oral appliance therapy in severe obstructive sleep apnea

Purpose In treatment for obstructive sleep apnea (OSA), oral appliance (OA) therapy is indicated in patients with mild–moderate OSA. However, since patients with severe OSA in whom OA therapy was effective have also been reported, it may not be possible to determine indications for OA therapy based on the severity alone. The purpose of this study was to determine indications for OA therapy using endoscopy during wakefulness in patients with severe OSA.

Development of a swallowing frequency meter using a laryngeal microphone

Disuse atrophy of swallowing-related organs is suspected when decreased swallowing frequency is seen in the elderly. However, swallowing frequency has not been examined in elderly people during daily life. We developed a swallowing frequency meter containing a laryngeal microphone that does not restrict the subjects ability to perform daily activities. In this study, the utility of the meter was assessed. Experiment 1: The ability of the meter to detect swallowing was examined. The subject was instructed to swallow saliva or foods at a voluntarily pace. During these procedures, swallowing events were simultaneously recorded by the meter, self-enumeration and videofluorography. As a result, all of the swallowing events identified by the meter coincided with the swallowing events identified by self-enumeration and videofluorography. Experiment 2: Swallowing sounds display various patterns both between and within individuals. Therefore, we examined the concordance rate between the number of swallowing events counted by the meter and that counted by self-enumeration in 15 subjects over a longer period than in experiment 1. The concordance rates calculated by two examiners between the meter and self-enumeration were 96·8 ± 4·5% and 98·9 ± 3·3% at rest and 95·2 ± 4·5% and 96·1 ± 4·1% during meals, respectively. Our findings indicate that this meter is useful for measuring the frequency of swallowing during daily situations.

Change in levator veli palatini muscle activity in relation to swallowing volume during the transition from the oral phase to pharyngeal phase

The aim of this study was to examine whether the levator veli palatini (LVP) muscle might be involved in the regulation of velopharyngeal function during the transition between the oral and pharyngeal phases during swallowing, and to examine whether LVP muscle activity could be regulated in relation to the volume of swallowing. Eight normal adults participated in this study. Smoothed EMG signals of the LVP muscle were collected. At the same time, palatoglossus muscle activity was also monitored. Each subject swallowed water at five different volumes: 12.5%, 25%, 50%, 100%, and 150 (or 200) % of the optimum volume for swallowing, which was individually determined for each subject. LVP muscle activity was positively correlated with changes in swallowing volume. The LVP muscle was involved in the regulation of swallowing during the transition from the oral to pharyngeal phases.

The efficacy of a lingual augmentation prosthesis for swallowing after a glossectomy: A clinical report

The excision of malignant tongue tumors often produces tongue defects that can cause dysphagia. A palatal augmentation prosthesis is frequently used to treat such dysphagia. This report describes a patient who received a palatal augmentation prosthesis after a glossectomy for malignant cancer of the tongue; however, no improvement was noted in swallowing function. A lingual augmentation prosthesis was then applied to the mandible, which resulted in improved swallowing function.

Predictors of Side Effects With Long-Term Oral Appliance Therapy for Obstructive Sleep Apnea

STUDY OBJECTIVES The aim of this study was to investigate the predictors of dental changes associated with long-term treatment with oral appliances (OAs) in patients with obstructive sleep apnea (OSA). METHODS This was a retrospective study to investigate Japanese patients with OSA receiving long-term treatment with OAs. Comparisons of cephalometric analysis were carried out between the initial and follow-up assessments of dental and skeletal changes. Based on dental changes, predictors that may cause side effects were investigated. RESULTS A total of 64 patients (average age at start of treatment: 57.7 ± 14.2 years, 44 males) were included in this study. The average duration of treatment was 4.3 ± 2.1 years. Over the total treatment period, there was a significant reduction in overjet (OJ) (1.5 ± 1.3 mm) and overbite (0.90 ± 1.5 mm), and an increase in the lower incisor line to the mandibular plane (3.1 ± 5.4°). A larger reduction in OJ of ≥ 1 mm was associated with treatment duration, use frequency, and mandibular advancement of the OAs. In addition to these predictive factors, the number of teeth was correlated with the amount of OJ reduction. CONCLUSIONS For long-term treatment with OAs, the risk of dental side effects should be considered, such as a reduction in OJ. A small number of maxillary teeth, as well as the factors associated with OAs, including treatment duration, use frequency, and mandibular advancement of the OAs, was correlated with an increased rate of OJ reduction. COMMENTARY A commentary on this article appears in this issue on page 7.

Influences of swallowing volume and viscosity on regulation of levator veli palatini muscle activity during swallowing

This study examined the aspect of the regulation of velum movement in the transition from the oral to pharyngeal phases of swallowing in relation to changes in the swallowing volume and viscosity by means of measurment of levator veli palatini muscle activity. The subjects were nine normal adults, ranging in age from 24 to 30 years. The swallowing volume was set at 1/4, 1/2 and 1 volume of the optimum volume of green tea for swallowing determined in each subject, and the viscosity was adjusted to 0, 2·0 and 4·6 Pa·s by mixing with thickener. Nine test foods were prepared in total. The electromyographic activity of the levator veli palatini muscle was monitored using bipolar hooked wire electrodes. The levator veli palatini muscle activity was defined as the integrated electromyographic wave. The mean in swallowing each test food was determined in each subject. The levator veli palatini muscle activity increased with the swallowing volume for all subjects (P < 0·05) and decreased inversely with the viscosity for six subjects (P < 0·05), but no change with the increase in the viscosity was noted for three subjects. This study clarified the aspect of the regulation of velar movement with regard to the involvement of the levator veli palatini muscle in swallowing activity with changes in the swallowing volume and viscosity.

Dental and skeletal changes associated with long-term oral appliance use for obstructive sleep apnea: A systematic review and meta-analysis

An oral appliance (OA) is an effective treatment option for patients with obstructive sleep apnea (OSA), but dental and skeletal changes have been detected by many studies after long-term OA use. Better understanding of the long-term side effects may decrease discontinuation of OA use and assist clinicians to make informed decisions. Accordingly, a systematic review and meta-analysis were performed to evaluate the dental and skeletal changes associated with OAs designed to advance the mandible. The quality of the studies was determined by using the risk of bias assessment tool for non-randomized studies (RoBANS), and 12 studies were included in the meta-analysis. OA use was associated with a significant decrease of overjet (OJ) and overbite (OB), and it was suggested that both parameters decreased along with the duration of treatment. Meta-analysis also demonstrated a significant increase of L1-MP. However, there were no significant changes of skeletal modifications or mandibular rotation. Changes of incisor inclination were suggested to make a contribution to reduction of OJ and OB. In conclusion, long-term OA use was associated with dental changes. The results of this study provide information for clinicians about the long-term effects of OAs.

Titration technique using endoscopy for an oral appliance treatment of obstructive sleep apnea

The degree of mandibular protrusion for an oral appliance (OA) should be customized for each patient with obstructive sleep apnea (OSA). This article describes the mandibular titration technique for OAs to effectively treat OSA by using endoscopy to evaluate the change in the airway at the velopharynx. This technique may minimize the degree of mandible protrusion and contribute to both the efficacy of and compliance with OA therapy.