Effects of a mandibular repositioner on obstructive sleep apnea

Cephalometric evaluation of pharyngeal airway and tongue space following treatment with Herbst and AdvanSync appliances : A prospective randomized clinical trial

OBJECTIVES

To evaluate and compare pharyngeal airway and tongue space changes after treatment with fixed functional appliances-Herbst and AdvanSync™ (Ormco, Orange, CA, USA) appliances-in skeletal class II patients in pre- and posttreatment lateral cephalograms.

METHODS

For this randomized, controlled trial, 40 patients (21 male, 19 female) were divided into two groups-a Herbst group (mean age 12.6 ± 0.67 years) and an AdvanSync group (mean age 12.8 ± 0.66 years). Pre- and posttreatment (appliance therapy duration-8 months) lateral cephalograms were traced using a software program to evaluate pharyngeal airway and tongue space changes.

RESULTS

Nasopharyngeal airway, velopharyngeal airway, glossopharyngeal airway, and hypopharyngeal airway increased in the Herbst group by 2.12 mm (p ≤ 0.001), 2.33 mm (p ≤ 0.001), 2.40 mm (p ≤ 0.01), and 1.57 mm (p ≤ 0.05), while in the AdvanSync group the increases were 1.89 mm (p ≤ 0.001), 1.21 mm (p ≤ 0.001), 1.18 mm (p ≤ 0.001), and 1.53 mm (p ≤ 0.001), respectively. In the Herbst group, tongue length and height increases were 2.04 mm (p ≤ 0.01) and 3.74 mm (p ≤ 0.001), while the values in the AdvanSync group were 2.41 mm (p ≤ 0.05) and 2.69 mm (p ≤ 0.001). The change of the tongue tip from the lower occlusal plane was 0.69 mm (p ≤ 0.001) in the Herbst group and 0.77 mm (p ≤ 0.001) in the AdvanSync group. The velopharyngeal airway dimension was correlated positively with that of the retroglossal oropharyngeal airway, which in-turn positively correlated with the laryngopharyngeal airway which correlated well with the distance of the tongue tip from the lower occlusal plane.

CONCLUSIONS

The airway dimensions and tongue parameters increased significantly in both treatment groups in the present study. These changes were higher in the Herbst appliance than in the AdvanSync group, except for the distance of the tongue tip from the lower occlusal plane. A significant difference between the pharyngeal airways was found only for the retropalatal oropharyngeal airway.

Impact of palatopharyngeal sizes changing on pharyngeal airflow fluctuation and airway vibration in a pediatric airway

Snoring is common in children and is associated with many adverse consequences. One must study the relationships between pharyngeal morphology and snoring physics to understand snoring progression. Although some model studies have provided fluid-structure interaction dynamic descriptions for the correlation between airway size and snoring physics, the descriptions still need to be further investigated in patient-specific airway models. Fluid-structure interaction studies using patient-specific airway structures complement the above model studies. Based on reported cephalometric measurement methods, this study quantified and preset the size of the palatopharynx airway in a patient-specific airway and investigated how the palatopharynx size affects the pharyngeal airflow fluctuation, soft palate vibration, and glossopharynx vibration with the help of a verified FSI method. The results showed that the stenosis anterior airway of the soft palate increased airway resistance and airway resistance fluctuations, which can lead to increased sleep effort and frequent snoring. Widening of the anterior airway can reduce airflow resistance and avoid obstructing the anterior airway by the soft palate vibration. The pharyngeal airflow resistance, mouth inflow proportion, and soft palate apex displacement have components at the same frequencies in all airway models, and the glossopharynx vibration and instantaneous inflow rate have components at the same frequencies, too. The mechanism of this same frequency fluctuation phenomenon can be explained by the fluid-structure interaction dynamics of an ideal coupled model consisting of a flexible plate model and a collapsible tube model. The results of this study demonstrate the potential of FSI in studying snoring physics and clarify to some degree the mechanism of airway morphology affecting airway vibration physics.

Anatomical phenotype of obstructive sleep apnea patients based on cluster analysis

OBJECTIVES

To generate a novel subtype of obstructive sleep apnea (OSA) based on anatomical features and verify the differences in the response of different subtypes to orthodontic treatment, thus providing a theoretical reference for clinical decision-making.

MATERIALS AND METHODS

A K-means cluster analysis was performed for this retrospective serial study, which includes 722 OSA patients, aged 44.0 (36.0, 54.0) years, 80.2% male, with apnea-hypopnea index (AHI) of 23.2 (13.4, 39.6) events·h-1 , and body mass index (BMI) of 25.47 ± 3.00 kg·m-2 . All samples were divided into three subtypes based on AHI, BMI, and five variables of craniofacial measurements. Sixty-seven cases with mandibular advancement devices (MAD) therapeutic results were further applied to validate the efficacy and side effects of this treatment in different subtypes.

RESULTS

Two hundred and thirty patients (31.9%) were characterized as cluster 1: AHI of 17.65 (11.80, 30.42) events·h-1 , BMI of 23.65 ± 2.62 kg·m-2 , with skeletal Class II high-angle shape. Cluster 2 included 278 patients (38.5%): AHI of 17.00 (11.00, 26.48) events·h-1 , BMI of 25.36 ± 2.53 kg·m-2 , soft palate length (SPL) of 39.25 mm (36.12, 42.20), with basically normal skeleton and normal airway size. Cluster 3, consisting of 214 patients (29.6%), exhibited a combination of anatomical deformity and obesity, with the highest AHI and BMI of 45.35 (30.42, 62.53) events·h-1 and 27.57 ± 2.59 kg·m-2 respectively, but less deformity degree than cluster 1. Cluster 2 had the highest response rate and relatively mild side effects with MAD.

CONCLUSIONS

Orthodontic treatment based on anatomical morphology could exert a better effect on mild-moderate OSA patients with mild skeletal deformity.

Obstructive Sleep Apnea Treatment with Oral Appliance in a Myotonic Dystrophy Type I Subject: A Case Report

Objective  to report a myotonic dystrophy type 1 (MD1) subject with obstructive sleep apnea syndrome treated with oral appliance. Methods  A review of individual's history and records, associated with a photographic register of all diagnostic methods and literature research about the topic were done. Final Statements  This case depicts the therapeutical choices disposable to treat subjects with obstructive sleep apnea and DM1. Although considered an uncommon treatment, the oral appliances, if well indicated in adequately selected cases, can satisfactorily improve respiratory parameters, symptoms and quality of life.

Role of craniofacial phenotypes in the response to oral appliance therapy for obstructive sleep apnea

BACKGROUND

Mandibular advancement device (MAD) is a good alternative for patients with obstructive sleep apnea (OSA). However, the treatment response varies amongst individuals.

OBJECTIVE

This study aimed to explore the role of craniofacial features in the response to MADs to improve prognostication and patient selection.

METHODS

The retrospective trial contained 42 males aged 41.5 ± 9.0 years, and with an apnea-hypopnea index (AHI) of 21.5 ± 13.8 events/h. According to the mandibular plane angle, participants were divided into three groups: low angle (n = 13), average angle (n = 14) and high angle (n = 15). Under the monitoring of home sleep testing, adjustable MADs were used to titrate the mandible forward from 0 mm with an increment of 0.5 mm every day. The polysomnography outcomes, mandibular protrusion amounts, changes in upper airway MRI measurements and nasal resistance were compared amongst the three groups.

RESULTS

The normalisation rate (AHI <5 /h) was 92.3%, 57.1% and 46.7%, respectively, in the low-, average- and high-angle groups (p = .027). The effective protrusion where AHI was reduced by half was 20 (11.3 ~ 37.5) %, 31.3 (23.6 ~ 50) % and 50 (36.9 ~ 64.9) % of the maximal mandibular protrusion, in the low-, average- and high-angle groups (p = .004). Multivariate logistic regression revealed that increased gonion angle (OR = 0.878) and baseline AHI(OR = 0.868) can reduce the probability of normalisation.

CONCLUSION

The high mandibular plane angle might be an unfavourable factor to MAD treatment and more protrusion was needed to achieve a 50% reduction in AHI. Vertical craniofacial pattern (gonion angle) and baseline AHI constituted the model for predicting the effect of MADs.

Oral appliance therapy for obstructive sleep apnea in multiple system atrophy with floppy epiglottis: a case series of three patients

PURPOSE

A recent study demonstrated that continuous positive airway pressure (CPAP) may exacerbate obstructive sleep apnea (OSA) in patients with multiple system atrophy (MSA) and a floppy epiglottis (FE) as the CPAP promotes downward displacement of the epiglottis into the laryngeal inlet. In this case series, we examined the effectiveness of an oral appliance (OA) for treating OSA in three patients with MSA and an FE.

METHODS

Patients with MSA were demonstrated to have an FE on fiberoptic laryngoscopy under sedation using intravenous propofol. The therapeutic intervention was fitting an OA. Polysomnography (PSG) was performed subsequently with the OA in place.

RESULTS

In three patients with MSA, some parameters used to assess the severity of OSA improved with an OA. Both apnea-hypopnea index (AHI) and arousal index (ArI) decreased while wearing the OA in two cases while in the third case, apnea index (AI) and cumulative time at peripheral oxygen saturation (SpO₂) below 90% (CT90) decreased, but AHI and ArI increased. The only side effects were transient TMJ discomfort, masseter muscle pain, and tooth discomfort.

CONCLUSION

OA therapy using a two-piece type mandibular advancement device (MAD) may be a useful treatment intervention for patients with OSA who have MSA and FE.

A new design of mandibular advancement device (IMYS) in the treatment of obstructive sleep apnea

OBJECTIVE

The mandibular advancement device (MAD) is currently suggested in patients with mild to moderate obstructive sleep apnea (OSA). This study investigated the effects of a new fully customizable MAD-type device called, "It Makes You Sleep" (IMYS), in patients with mild to moderate OSA.

METHODS

Sixteen patients (14 men and 2 women; mean age 62; SD ± 11 years) were retrospectively enrolled. Each patient received home sleep apnea testing (HSAT) at baseline (T0) and after three months (T1) of IMYS treatment. The Apnea-Hypopnea Index (AHI), the Oxygen Desaturation Index (ODI), the Minimum Oxygen Saturation (minSO2) and the Medium Oxygen Saturation (medSO2) were analyzed.

RESULTS

From T0 to T1, the IMYS treatment showed a significant reduction of AHI and ODI and a significant increase of minSO2 and medSO2.

CONCLUSION

The IMYS appliance is an effective device for treating mild or moderate OSA.

The public health burden of obstructive sleep apnea

Obstructive sleep apnea (OSA) is the most common respiratory disorder of sleep. The vast majority (>80%) of adults with moderate to severe OSA remain undiagnosed. The economic costs associated with OSA are substantial for both the individual and society as a whole; expenses are likely to be underestimated given that the disease remains undiagnosed in such a large percentage of individuals. The economic burden of motor vehicle collisions related to OSA alone is significant; it is estimated that 810,000 collisions and 1400 fatalities from car crashes in the United States were attributable to sleep apnea in 2000. The many health consequences of OSA include daytime sleepiness, reduced quality of life, decreased learning skills, and importantly, neurocognitive impairments that include impaired episodic memory, executive function, attention and visuospatial cognitive functions. Untreated OSA leads to numerous medical problems such as cardiovascular diseases that can potentially increase healthcare utilization. Untreated patients with sleep apnea consume a disproportionate amount of healthcare resources, expenditures that decrease after treatment. The gold-standard management of OSA remains treatment with CPAP (Continuous Positive Airway Pressure), which is effective in eliminating sleep fragmentation and preserving nocturnal oxygenation, thereby improving daytime sleepiness and quality of life. However, its impacts in reversing neurocognitive function are still uncertain. A significant impediment to CPAP effectiveness is low adherence rates (ranges from 50% to 75%). It is commonly accepted that CPAP improves excessive drowsiness; hence meliorates attention, and accumulating data suggest that CPAP improves a variety of other outcomes such as the risk of motor vehicle crashes.

The interaction of obesity and craniofacial deformity in obstructive sleep apnea

OBJECTIVE

Both obesity and craniofacial deformity are important etiologies of obstructive sleep apnea (OSA). The present research aimed to explore their interaction and different impacts on OSA severity.

METHODS

A total of 207 consecutive OSA patients (169 males, 38 females) were included in the research. Based on the body mass index (BMI) value, patients were divided into 77 normal-weight patients (BMI <24 kg m^-2), 105 overweight patients (24 ≤ BMI<28 kg m^-2) and 26 obese patients (BMI ≥28 kg m^-2). All accepted overnight polysomnography and standard lateral cephalogram. Cephalometric measurements involved 25 cephalometric variables. The correlations between these cephalometric variables, BMI and the apnea-hypopnea index (AHI) were evaluated.

RESULTS

For the whole sample after controlling for gender and age, stepwise regression analysis showed that the factors affecting AHI were increased BMI, narrowing posterior airway space, inferior displacement of hyoid and elongation of the tongue. When grouped by BMI, normal-weight group exhibited with more reduced maxillary length and mandible length, and steeper mandible plane than overweight and obese patients (p < 0.0167). Obese group showed least skeletal restriction and most prominent soft tissues enlargement (p < 0.0167). However, these skeletal indexes were not statistically correlated with AHI.

CONCLUSIONS

Obesity and skeletal malformations were both etiological factors of OSA, but obesity seemed to have a greater influence on AHI severity in all kinds of obese and thin OSA patients. Only in normal-weight group, it was affected by both cephalometric variables and BMI.

A consideration of factors affecting palliative oral appliance effectiveness for obstructive sleep apnea: a scoping review

STUDY OBJECTIVES

This scoping review allows physicians, researchers, and others interested in obstructive sleep apnea to consider effectiveness of oral appliances (OAs). The intent is to improve understanding of OA effectiveness by considering morphologic interaction in patients with obstructive sleep apnea.

METHODS

Morphologic and biomechanical criteria for positional alterations of the mandible assessed success rates of OA appliances. Searches of databases (Medline, PubMed, The Cochrane Library, EBSCO) using terms: OA treatment effectiveness and positive and/or negative outcome predictors. Craniofacial predictors of OAs and obstructive sleep apnea biomechanical factors of anatomical traits associated with OA effectiveness were included. Databases searched radiographic cephalometric imaging for morphology/phenotypes and apnea-hypopnea index responses. Articles were excluded if title or abstract was not relevant or a case report. If the analysis did not report mean or standard deviation for apnea-hypoxia index, it was excluded. No language, age, or sex restrictions were applied.

RESULTS

Analysis of 135 articles included in searched literature indicated alterations in musculature and pharyngeal airway structure through OA use. These alterations were individually unpredictable with wide variability 61.81% ± 12.29 (apnea-hypoxia index mean ± standard deviation). Morphologic variations as predictors were typically weak and idiosyncratic. Biomechanical factors and wide variations in the metrics of appliance application were unclear, identifying gaps in knowledge and practice of OAs.

CONCLUSIONS

An integrated basis to identify morphologic and biomechanical elements of phenotypic expressions of sleep-disordered breathing in the design and application of OAs is needed. Current knowledge is heterogeneous and shows high variability. Identification of subgroups of patients with obstructive sleep apnea responding to OAs is needed.

Pharyngeal airway dimension in patients before and after treatment of myofascial pain syndrome

Objective: This study aimed: (1) to assess the localization of the anatomic landmarks of the pharyngeal airway on cone beam computed tomography (CBCT) images; and (2) to evaluate if resolution of myofascial pain syndrome (MPS) changed the airway dimensions.Methods: Twenty-nine patients with pre- and post-treatment CBCT scans were randomly selected to locate five landmarks twice, with a two-week interval. The same landmarks were used to measure the airway volume and minimal cross-sectional area (CSA_min).Results: The intra-observer reliability (ICC) was 0.99-1.00 for volumetric and CSA_min measurements, based on the five landmarks used. The paired t test showed no significant difference in the airway volume (p = 0.68) and CSA_min (p = 0.96).Discussion: The outcomes showed that the landmarks used had excellent ICCs for the volumetric and CSA_min measurements. There was no change in volume and CSA_min of the pharyngeal airway after resolution of MPS.

Multislice Computed Tomography Assessment of Airway Patency Changes Associated with Mandibular Advancement Appliance Therapy in Supine Patients with Obstructive Sleep Apnea

The purpose of the present study was to measure the regional effects of the mandibular advancement appliance (MAA) on the upper airway of supine subjects with obstructive sleep apnea (OSA) using multislice computed tomography (MSCT). The subjects included 8 males and 5 females who were diagnosed with mild to moderate OSA and were referred to the Orthodontic Clinic of Hiroshima University Hospital, where they underwent MAA therapy. Using a CT scanner, baseline MSCT images were obtained from the subjects without the MAA for morphological analysis, and then the experimental images were obtained while wearing the MAA. To measure the anteroposterior diameter, width, and cross-sectional area of the oropharynx region of interest (ROI), five distance variables were first defined on each multiplanar reconstruction (MPR) image using OsiriX. Additionally, the volumes of the upper airway, bony hard tissue, and soft tissue (soft palate and tongue) in the oro-hypopharyngeal region were measured. In most of the assessed airway size variables, significant increases in the anteroposterior diameter and width were observed after MAA therapy. Regarding the upper airway cross-sectional area, all the upper airway size variables exhibited significant increases. In the volumetric analysis, a significant increase was observed in airway volume, whereas the soft tissue volume in the oro-hypopharyngeal region did not show the significant decrease after MMA therapy. However, from a different point of view, the volumes of the upper airway and soft tissue significantly increased and decreased, respectively, as demonstrated by the calculated ratio for the oro-hypopharyngeal region. We demonstrated that the proportional size of the soft tissue volume, i.e., the soft palate and tongue in the oro-hypopharyngeal region, significantly decreased during use of an MAA. This forward displacement of the soft tissue thereby increases the retroglossal airway space (except the nasopharynx) three-dimensionally.

Comparison of the Changes in Hyoid Bone Position in Subjects with Normodivergent and Hyperdivergent Growth Patterns: A Cephalometric Study

Objective

The aim of this study is to test the hypothesis that there is no difference in hyoid bone position among individuals with different growth patterns before and after treatment.

Materials and Methods

Pre- and post-treatment lateral cephalogram of forty Class I adults in the age group of 20–27 years were grouped. All the cases were treated with the first premolar extraction in all quadrants. Based on the growth pattern of the face, individuals were divided into: (1) Group 1 (n = 20): Normodivergent, i.e., FH/MP angle smaller than 30.5° (20 patients). (2) Group 2 (n = 20): Hyperdivergent, i.e., FH/MP angle larger than 30.5° (20 patients). Lateral cephalograms were traced and analyzed manually for evaluation of hyoid bone position. Patients in both groups were treated with preadjusted appliances. Pre- and post-treatment lateral cephalograms were traced, and variables were compared using paired t-test, and the relationship between dentofacial variables, growth pattern, and the hyoid bone position was analyzed using Karl Pearson’s correlation coefficient method. The changes of hyoid position after treatment were compared using t-test.

Results

The data were analyzed by Kolmogorov–Smirnov and paired t-test. Karl Pearson’s correlation coefficient test was performed to determine whether there was an association between the changes of hyoid and growth pattern. Following retraction of incisors, statistically significant correlation was observed in the pre- and post-treatment values of dentofacial structures and hyoid bone, but no significant correlation was found in position of the hyoid bone in the normodivergent and hyperdivergent groups. In both the groups, hyoid bone moved in an inferior and posterior direction after orthodontic treatment.

Conclusion

No change was seen in position of the hyoid bone in normodivergent and hyperdivergent groups.

A Comparison of Different Success Definitions in Non-Continuous Positive Airway Pressure Treatment for Obstructive Sleep Apnea Using Cardiopulmonary Coupling

STUDY OBJECTIVES

The definition and the criteria for the successful treatment of obstructive sleep apnea vary, depending on the study. This study aimed to compare different success criteria of non-continuous positive airway pressure (non-CPAP) treatment for obstructive sleep apnea in terms of sleep quality by using cardiopulmonary coupling.

METHODS

We included 98 patients who had been treated with sleep surgery or with a mandibular advancement device at our sleep clinic from January 2011 to March 2013. The success and failure groups were divided by 6 criteria that have been used in the literature. The validity of each of the 6 criteria was evaluated by cardiopulmonary coupling-based sleep quality.

RESULTS

The parameters of cardiopulmonary coupling indicated that sleep quality improved with non-CPAP treatment: low-frequency coupling decreased from 57.4% ± 17.7% to 46.9% ± 16.5%, whereas high-frequency coupling increased from 30.2% ± 17.1% to 37.4% ± 16.7%. In multiple regression analysis, only the criterion of a reduction in the apnea-hypopnea index greater than 50% was significantly associated with sleep quality improvement (p = 0.016; 95% confidence interval, 1.008-1.076 in the high-frequency coupling increment; p = 0.001; 95% confidence interval, 1.025-1.099 in the low-frequency coupling decrement).

CONCLUSIONS

Cardiopulmonary coupling analysis showed that a reduction in the apnea-hypopnea index of more than 50% might be the optimal criterion to determine the success or failure of non-CPAP treatment in terms of sleep quality.

Effect of retraction of anterior teeth on pharyngeal airway and hyoid bone position in Class I bimaxillary dentoalveolar protrusion

BACKGROUND

To test the hypothesis that the retraction of anterior teeth has no effect on the dimensions of pharyngeal airway and to evaluate the retraction of anterior teeth on each parameter of pharyngeal airway.

METHODS

Twenty-two adult patients of Class I bimaxillary protrusion requiring first premolar extractions with maximum anchorage requirements were selected. The pharyngeal airway and dentofacial parameters of the patients were compared using pre- and post-treatment lateral cephalograms with the help of Student's paired t-test (P < 0.05). The relationship between airway size and dentofacial parameters was also evaluated using Pearson correlation coefficient.

RESULTS

The upper and lower lips were retracted by 2.25 and 5.4 mm after retraction of the incisors. The tips of upper and lower incisors were retracted by 7.75 and 7.15 mm, respectively. There was a statistically significant decrease in SPP-SPPW (P < 0.05), U-MPW (P < 0.001), TB-TPPW (P < 0.001), and change in HRGN (P < 0.01). A significant correlation was observed between the amount of retraction of lower incisor and decrease in the pharyngeal airway posterior to soft palate (r = 0.102), tongue (r = 0.322), and change in HRGN (r = 0.265).

CONCLUSIONS

The size of the pharyngeal (velopharyngeal and glossopharyngeal) airway reduced and hyoid bone position changed after retraction of the incisors in extraction space in bimaxillary protrusive adult patients.

Management of sleep apnea: a critical look at intra-oral appliances

With so many disciplines of both medicine and dentistry involved in the treatment of obstructive sleep apnea (OSA), several forms of therapy are available. The orthodontist is rarely considered when the diagnosis of chronic obstructive sleep apnea (OSA) is delivered. However, the scope of orthodontic care today is much broader than the mere alignment of teeth. While the current gold standard for OSA care remains continuous positive air pressure (CPAP), the patient may be given a prescription for an intra-oral sleep appliance. When orthodontists work in concert with their medical colleagues to provide a sleep appliance, several considerations must be made including the evidence regarding oral appliance efficacy. For some patients, oral appliances are highly successful; however, even for responsive patients, there are risks associated with oral appliance therapy. The aim of the paper was to present a critical review of the current level of evidence for the use of oral appliances in the treatment of OSA. A substantial number of publications ranging from case reports, uncontrolled and controlled case series, prospective randomized studies, and even a small number of systematic reviews were available. The existing systematic reviews were based on either a limited number of prospective studies with limited numbers of patients or in some cases were based on subjective data only. As a result, a narrative review of the literature was performed that discusses objective clinically testable criteria and recent developments that may aid future research investigations.

Anatomically Based Outcome Predictors of Treatment for Obstructive Sleep Apnea with Intraoral Splint Devices: A Systematic Review of Cephalometric Studies

AIMS

The aim of this review is to summarize data from the literature on the predictive value of anatomy-based parameters, as identified by cephalometry, for the efficacy of mandibular advancement devices (MAD) for the treatment of obstructive sleep apnea (OSA).

METHODS

Articles were initially selected based on their titles or abstracts. Full articles were then retrieved and further scrutinized according to predetermined criteria. Reference lists of selected articles were searched for any missed publications. The selected articles were methodologically evaluated.

RESULTS

Of an initial 311 references, 13 were selected that assessed correlations between polysomnographic and cephalometric variables. The majority of studies demonstrated a correlation between treatment effectiveness and features as determined by cephalometric analysis, such as the mandibular plane angle, hyoid bone distance to mandible, antero-posterior diameter of the maxilla, tongue area, cranial base, and soft palate.

CONCLUSIONS

The mandibular plane angle and the distance between hyoid bone and mandibular plane was found to have a predictive value for MAD effectiveness in OSA patients. However, the relative weak and somewhat inconsistent cephalometric data suggest that decisions based solely on these factors cannot be recommended, especially because an integrated analysis of other risk factors (e.g., age, sex, BMI) should also be taken into account.

An evaluation of two different mandibular advancement devices on craniofacial characteristics and upper airway dimensions of Chinese adult obstructive sleep apnea patients

OBJECTIVES

To evaluate the effects of two different mandibular advancement devices (MADs) on craniofacial characteristics and upper airway dimensions of Chinese adult patients with obstructive sleep apnea (OSA).

MATERIALS AND METHODS

Forty-five patients with OSA were recruited as part of a prospective randomized crossover trial for treatment with two different MADs. Lateral cephalograms were taken, and the Epworth Sleepiness Scale and the Sleep Apnea Quality of Life Index were completed at baseline.

RESULTS

The Apnea-Hypoxia Index was highly significantly reduced with the monoblock (P < .001) and significantly reduced with the twin block (P < .01). The monoblock demonstrated a superior result than the twin block (P < .05). A significant reduction was found in the distances between the hyoid bone to retrognathia (monoblock, P < .01; twin block, P < .001) as well as the distance between the hyoid bone and mandibular plane angle (P < .001). Furthermore, soft palate length increased significantly (P < .05) with both MADs. However, the changes did not differ in favor of either MAD.

CONCLUSION

Monoblock was the better MAD to improve OSA severity. No difference could be found in changes of subjective OSA indicators. Significant but similar cephalometric changes were observed, indicating both MADs alter the position of the surrounding musculature and improve upper airway patency. Therefore, the different design features of the MADs suggest an impact on some OSA indicators.

The status of cephalometry in the prediction of non-CPAP treatment outcome in obstructive sleep apnea patients

Obstructive sleep apnea syndrome (OSAS) is the most common sleep disordered breathing disorder (SDB) in adults and is characterized by a recurrent partial or complete collapse of the upper airway during sleep. This can be caused by many factors, sometimes interacting, such as skeletal malformations, soft tissue crowding, respiratory instability and the various effects of aging, obesity and gender that dictate craniofacial and upper airway anatomy. Research has demonstrated that the majority of patients exhibit at least one anatomical component such as retrognathia or a narrow posterior airway space that predisposes to the development of OSAS. Within the predisposing elements for OSAS many seem to point to anatomical characteristics. A standardized and relatively simple radiologic technique to evaluate anatomical craniofacial relationships is cephalometry. This has been used already for a long time in orthodontics, but is now gradually being introduced in OSAS treatment to envisage optimal treatment selection as well as to predict treatment outcomes. The purpose of the present review is to evaluate the contribution of cephalometry in the prediction of outcomes from OSAS treatments that depend on the upper airway morphology in their mechanisms of action such as oral appliances that advance the mandible as well as various surgical methods. In addition, an overview of imaging modalities and methods that currently are being used in cephalometric analysis in OSAS patients is provided. The findings indicate that isolated cephalometric parameters cannot be used to reliably predict treatment outcomes from mandibular advancement devices and surgical methods for OSAS. Extreme or outlying values of cephalometric parameters may rather be used as contra-indicators or 'red flags' instead of predictors.

Effects of varying mandibular protrusion and degrees of vertical opening on upper airway dimensions in apneic dentate subjects

INTRODUCTION

Despite numerous studies investigating the dimensional and therapeutic effects of mandibular advancement splints (MASs), data regarding the effects of differently designed individual and non-adjustable MASs on the upper airway in fully dentate apneic subjects in the sagittal plane including comparison of these effects with a placebo device are sparse. The present study aimed to determine the dimensional changes in the sagittal plane created by differently designed MASs in the upper airway in fully dentate apneic subjects and to compare these changes with the effects of a placebo device.

MATERIALS AND METHODS

Magnetic resonance (MR) images of 9 dentate apneic subjects with 5 differently designed MASs and without a MAS were obtained. We measured the area of the entire pharynx (velopharynx, oropharynx, hypopharynx) on these MR images and compared the dimensional changes.

RESULTS

The dimensional changes triggered by two specific MASs (75% of the maximum mandibular protrusion with 5 mm vertical opening, and 75% of the maximum mandibular protrusion with 10 mm of vertical opening) in the entire pharynx in the sagittal plane were statistically significant compared to the other MASs (p < 0.05). The MAS effecting 75% of the maximum mandibular protrusion and 10 mm of vertical opening created a significant dimensional increase only in the velopharyngeal area among the three pharyngeal sites (p ≤ 0.003).

CONCLUSION

While the degree of mandibular protrusion created by the MAS affects the dimensions of the upper airway, the degree of the vertical opening exerts no significant dimensional effect in the sagittal plane in fully dentate apneic patients. The mandibular protrusion effect is comparatively larger in the velopharyngeal region.

Cephalomteric changes in airway dimensions with twin block therapy in growing Class II patients

Introduction:

Myofunctional appliances are commonly used for correction of skeletal Class II malrelationship. These appliances influence craniofacial and nasopharyngeal dimensions.

Objectives:

The present study was done to evaluate changes in airway with twin block therapy.

Materials and Methods:

Cephalometric assessment of airway was done in 25 growing children in the age group of 11-13 years with Class II skeletal pattern. All the patients were treated with twin block appliance. Pre and post treatment lateral cephalograms were taken to evaluate the changes in different airway and craniofacial dimensions during the treatment period. The average treatment duration was 14.5 months.

Results:

Airway: A significant increase was observed in upper and lower pharyngeal width and area of bony nasopharynx. Craniofacial dimension: There was a significant increase in effective mandibular length, ramal length and mandibular plane angle. There was an increase in SNB angle, which resulted in decreased ANB angle.

Conclusion:

There was a definite improvement in airway dimension following twin block therapy

Long-term therapeutic efficacy of oral appliances in treatment of obstructive sleep apnea-hypopnea syndrome

Objective:

To investigate the long-term efficacy and safety of oral appliances (OAs) in treating obstructive sleep apnea-hypopnea syndrome (OSAHS) by length of treatment.

Materials and Methods:

This is a retrospective study to review the usage of OAs in Chinese OSAHS patients in recent decades. Ninety-four valid questionnaires were returned by 412 patients with OSAHS receiving OA treatment. Among the wearers, 22 agreed to follow-up polysomnography, and 25 agreed to follow-up cephalograms. Tolerance and side effects of OAs were assessed by a survey. Comparisons of efficacy were carried out between the initial and follow-up polysomnography measurements. Cephalometric analysis was used to investigate skeletal and occlusal changes to determine safety of the OAs.

Results:

The longest treatment extended to 147 months, with a median of 74 months (first and third quartiles, 30 and 99 months, respectively). Among the participants, 14.9% had been treated for more than 120 months. Side effects were temporary and relatively minimal and included tooth soreness (37.2%), dry mouth (33.0%), odd bite feeling (31.9%), and excess salivation (30.8%). Polysomnography proved that OAs remained effective for the treatment of OSAHS in the long term; initial Apnea-Hypopnea Index values were reduced from a median of 24.50 (quartiles, 14.65, 54.05) without the OA to 7.40 with the OA (2.12, 10.00), and follow-up median values were 25.55 without the OA (11.71, 43.65) and 4.25 with the OA (1.38, 7.70). Cephalometric analysis indicated mild and slow changes in the skeleton and occlusion after average treatment duration of 5 years.

Conclusion:

OAs provided effective and safe long-term therapy for patients with OSAHS. Follow-up supervision is recommended since long-term alterations take place, although these appear to be minimal.

Changes of pharyngeal airway size and hyoid bone position following orthodontic treatment of Class I bimaxillary protrusion

Objectives:

To test the hypothesis that the sagittal position of the anterior teeth has no effect on pharyngeal airway dimension or hyoid bone position and to investigate the influence of orthodontic retraction of the anterior teeth on each section of pharynx and hyoid position.

Materials and Methods:

Forty-four Class I bimaxillary protrusion adults, treated with preadjusted appliances and maximum anchorage after extraction of four premolars, were divided into two groups according to their vertical craniofacial skeletal patterns. Pretreatment and posttreatment variables were compared using paired t-test, and the relationship between pharyngeal airway size and dentofacial variables was analyzed using Pearson correlation coefficient. The changes of pharyngeal airway size and hyoid position after treatment were compared between two groups using independent t-test.

Results:

Upon retraction of the incisors, the upper and lower lips were retracted by 2.60 mm and 3.87 mm, respectively. The tip of upper incisor was retracted by 6.84 mm and lower incisor retracted by 4.95 mm. There was significant decrease in SPP-SPPW, U-MPW, TB-TPPW, V-LPW, VAL, C3H, and SH (P &lt; .05). No statistically significant different changes were observed in the dentofacial structures, pharyngeal airway, and hyoid position between the two groups after the treatment. There was a significant correlation between the retraction distance of lower incisor and the airway behind the soft palate, uvula, and tongue.

Conclusions:

The pharyngeal airway size became narrower after the treatment. Extraction of four premolars with retraction of incisors did affect velopharyngeal, glossopharyngeal, hypopharyngeal, and hyoid position in bimaxillary protrusive adult patients.

Anatomy and physiology of the upper airway

The nose is the major portal of air exchange between the internal and external environment. The nose participates in the vital functions of conditioning inspired air toward a temperature of 37°C and 100% relative humidity, providing local defense and filtering inhaled particulate matter and gases. It also functions in olfaction, which provides both a defense and pleasure for the individual. Understanding normal physiology provides the basis for recognizing abnormalities.

Randomised cross-over study of oral appliances for snoring

OBJECTIVES

To compare a mandibular advancement splint to a control bite raising appliance in the treatment of snoring with or without mild obstructive sleep apnoea syndrome.

DESIGN

A prospective two-treatment randomised cross-over clinical trial.

SETTING

Single centre secondary care Dental Hospital.

PARTICIPANTS

Fifty-two subjects (36 men, 16 women) diagnosed with non-apnoeic snoring or mild obstructive sleep apnoea syndrome (apnoea/hypopnoea index < or =15 events/h), were recruited from Departments of Respiratory Medicine and ENT surgery, Newcastle upon Tyne Hospitals NHS Foundation Trust.

MAIN OUTCOME MEASURES

The Snoring Symptoms Inventory questionnaire (SSI) and the Epworth Sleepiness Score (ESS) were used to evaluate changes in symptoms. Patient reported outcomes (compliance, adverse events, splint preference) were recorded by questionnaire. Subjects attended for five study visits and used a mandibular advancement splint and a bite raising appliance at home each for 4 weeks, with a 3-week washout period between devices.

RESULTS AND CONCLUSIONS

Thirty-eight subjects completed the study. Both the mandibular advancement splint and bite raising appliance significantly reduced the SSI compared to the baseline scores: mandibular advancement splint 5.5, P = 0.013; bite raising appliance 3.1, P = 0.005. No statistically significant difference between the two treatment periods was detected (P > 0.05). The reduction in the Epworth Sleepiness Score was: mandibular advancement splint 1.0, P = 0.02; bite raising appliance 0.3, P = 0.4. The change in the Epworth Sleepiness Score was not statistically significantly different between the mandibular advancement splint and bite raising appliance treatment periods (P > 0.05).

CONCLUSIONS

In this cohort of patients diagnosed with snoring +/- mild OSA: 1 both the mandibular advancement splint and bite raising appliance designs of splint appeared to reduce the symptoms of snoring; 2 no difference in the magnitude of this effect was detected in favour of one design of splint.

[Tongue fixation system for therapy of sleeping disorders. A feasibility study]

INTRODUCTION

Forward displacement of the tongue is a verified principle in the therapy of sleep disorders which prevents the tongue from sinking backwards thus avoiding obstruction of the upper respiratory tract during sleep. In this feasibility study a novel oral appliance which connects to a pin implanted within the tongue was investigated.

METHODS

A new tongue positioning system using previously implanted tongue piercings as a pivot was developed. By pulling the tongue forward the oral device prevents airway obstruction. In our study we fitted 10 subjects who already had the tongue pierced with the developed oral device. The subjects underwent two nights of polysomnography with and without using the tongue positioning system. Wearing comfort and side effects were evaluated using a questionnaire. Moderate alcohol consumption was used to provoke snoring or apnea in the subjects. Tongue positioning with and without the device was visualized with oropharyngeal MRI.

RESULTS

Subjects did not report any discomfort or side effects wearing the device. Subjects showed only moderate snoring or apnea after alcohol consumption and snoring after alcohol consumption was reduced with the device. The average apnea/hypopnea index (AHI) was 0.8/h without the device. Using the device led to an increase of apnea in the subjects. MRI visualization showed that the device did not keep the upper airway space opened by fixing the tongue.

CONCLUSION

The effectiveness of the tongue positioning system should be improved by a modification which should be investigated in patients with preexisting sleep disorders.

A comparison study of upper airway among different skeletal craniofacial patterns in nonsnoring Chinese children

OBJECTIVE

Patients with OSAS (obstructive sleep apnea syndrome) demonstrate decreased upper airway dimension and craniofacial skeletal abnormalities. The study was performed to analyze whether upper airway dimensions differed among Chinese nonsnoring children of different sagittal and vertical skeletal facial morphologies.

MATERIALS AND METHODS

Lateral cephalometric records were used to measure the dimensions of the upper airway. Two groups of subjects were studied. A group of subjects with a normodivergent facial pattern (n = 190; FH-MP angle between 23.5 degrees and 30.5 degrees ) was divided into three subgroups according to ANB angle (Class I, II, or III). A second group of subjects with a normal sagittal facial pattern (n = 180; ANB angle between 0.7 degrees and 4.7 degrees ) was divided into three subgroups according to the FH-MP angle (low angle, normal angle, or high angle). All subgroups were matched for age and sex.

RESULTS

In the group of subjects with a normodivergent facial pattern, a significant tendency for reduced upper airway dimension in the inferior part (palatopharyngeal and hypopharynx) was found in the Class III, Class I, and Class II subgroups, in that order. In the group of subjects with a normal sagittal facial pattern, the superior part of the airway (nasopharyngeal and palatopharyngeal) decreased with increasing mandibular plane angle.

CONCLUSION

The sagittal and vertical skeletal patterns may be contributory factors for the variation of the inferior and superior part of the upper airway, respectively. Skeletal deficiency of nonsnoring Chinese children may predispose them to upper airway obstruction.

Effects of mandibular advancement on upper airway dimension and collapsibility in patients with obstructive sleep apnea using dynamic upper airway imaging during sleep

OBJECTIVES

The objective of this study was to evaluate the effects of mandibular advancement on oropharyngeal dimension and collapsibility and reveal the predominate site of change produced by mandibular advancement in patients with obstructive sleep apnea (OSA).

STUDY DESIGN

Sixteen adults (13 males and 3 females) with symptomatic mild to severe OSA participated. Custom-made silicone mandibular positioners were used to keep the mandible at 67% of maximum advancement. Changes in the oropharyngeal size and collapsibility with mandibular advancement were evaluated using ultrafast computed tomography taken during wakefulness and midazolam-induced sleep. Cross-sectional areas were assessed using electron beam tomography at 4 levels: high retropalatal (HRP), low retropalatal (LRP), high retroglossal (HRG), and low retroglossal (LRG).

RESULTS

During sleep, the minimum cross-sectional areas decreased 36.5%, 67.8%, 75.5%, and 65.8% at each level of HRP, LRP, HRG, and LRG respectively, as compared with those measured during wakefulness. Mandibular advancement during sleep increased 75.7%, 141.3%, 128.1%, and 119.9% at each level. The oropharynx showed 70.3%, 110.4%, 140.3%, and 156.9% increase in the Collapsibility Indices during sleep at each level of HRP, LRP, HRG, and LRG, respectively, compared with wakefulness. However, collapsibility indices decreased 29.1%, 23.2%, 21.4%, and 34.1% at each level with mandibular advancement.

CONCLUSION

Mandibular advancement increases oropharyngeal diameter and decreases oropharyngeal collapsibility during midazolam-induced sleep respiration at the retropalatal as well as the retroglossal region in most patients with OSA.

A Removable Snore Reduction Appliance for a Mandibular Edentulous Patient

A snore reduction appliance can be constructed for the atrophic mandibular edentulous patient. Two endosseous implants can be surgically placed that retain a complete mandibular denture and, in turn, an overlying bimaxillary removable snore reduction appliance. A dual laminate appliance is vacu-form fitted to the maxillary teeth and the mandibular denture and luted in a protrusive relation with cold cure acrylic. The appliance maintains the mandible in a protrusive position to open the upper airway to reduce snoring.

Evaluation of the human airway using cone-beam computerized tomography

OBJECTIVE

The goal of this project was to define and measure human airway space with radiographic volumetric 3-dimensional imaging and digital reconstruction of the pharynx using cone-beam computerized tomography.

STUDY DESIGN

This was a randomized retrospective study. Ten patient scans were selected randomly from a pool of 196 subjects seeking dental treatment at the University of California, San Francisco. Digital Imaging and Communications in Medicine-format volume images were captured using a low-radiation rapid-scanning cone-beam computerized tomography system (Hitachi MercuRay).

RESULTS

Detailed progressive rostrocaudal cross-sectional area histograms indicated that 8 of the 10 subjects demonstrated a region of maximum constriction near the oropharynx level. The most restricted cross-sectional area varied from 90 mm(2) to 360 mm(2).

CONCLUSIONS

The maximum constriction of the airway in 10 subjects quietly breathing for 10 seconds indicated variation in the level of the pharynx and the extent of the rostrocaudal zone of restriction.

Short-term effects of oral appliances with equal bite-raising distance but with varying protrusions on occlusal force, contact area and load center

The purpose of this study was to demonstrate how short-term wearing of an oral appliance (OA) with equal bite-raising distance but with varying protrusions affects occlusal force, contact area and load center. Twelve young healthy volunteers participated. With the appliance, the mandible was protruded 0%, 45%, 60% and 75% of maximum protrusion capacity, with 10 mm bite-raising between the first molars. The occlusal force, contact area and load center at maximum voluntary clenching were measured before wearing the OA, at 1 h, 3 h and 6 h during wearing, and 1 h after removal. When compared to the values before wearing the OA, occlusal force was significantly lower at 1 h, 3 h and 6 h during wearing in the case of no mandibular protrusion, and at 3 h and 6 h after for 45%, 60% and 75% of maximum mandibular protrusion (P < 0.05). Occlusal contact area was significantly smaller at 1 h and 6 h during wearing in the case of no protrusion, and at 6 h during wearing in the case of 45% of maximum protrusion (P < 0.05). There was a tendency for anterior shift in the location of the occlusal load center at 3 h and 6 h during wearing of the OA with any level of maximum protrusion. No significant change in these three measurements was found at 1 h after removal of the OA. The present study demonstrated that wearing an OA had only a marginal and transient influence on oral functions when their changes were compared before and after wearing the OA.

Airway and Craniofacial Changes With Mandibular Advancement Device in Chinese With Obstructive Sleep Apnoea

Introduction: The objective of this study was to investigate whether a reduction of obstructive sleep apnoea (OSA) severity is associated with significant airway and craniofacial changes with mandibular advancement device (MAD) in Chinese subjects. Materials and Methods: A total of 14 Chinese subjects (8 males, 6 females) diagnosed with OSA by overnight polysomnography (PSG), were fitted with the MAD. The mean ± standard deviation baseline apnoea-hypopnoea index (AHI) was 38.4 ± 17.2 and minimum arterial oxygen saturation (SaO2) was 75.5 ± 11.1%. The second lateral cephalogram was taken (wearing the MAD) after the second PSG. The second PSG was indicated when symptoms have improved as shown by the Epworth Sleepiness Score and sleep questionnaire after wearing the MAD for 1 month. Comparison of cephalometric variables was done to evaluate the effects of the MAD on the upper airway and anatomical variables. Pre-treatment versus post-treatment variables were compared using Wilcoxon signedrank test to determine the statistical significance at the 5% levels. The changes in airway variables were correlated with the changes in AHI using the Spearman correlation test. Results: At the second polysomnogram, AHI was significantly reduced to 10.9 ± 14.7. Minimum SaO2 was significantly increased to 86 ± 8.4%. Mean airway dimension was significantly increased at the nasopharyngeal area from 22.7 ± 3.0 mm to 24.8 ± 2.1 mm. The distance of the hyoid bone to the mandibular plane was significantly reduced with the MAD from a mean of 21.2 ± 5.7 mm to 13.9 ± 7.0 mm (P <0.05). This reduction of the distance of the hyoid bone to the mandibular plane was significantly correlated with the reduction in the AHI. Conclusion: An increase in the nasopharyngeal airway and reduction of the distance of the hyoid bone to the mandibular plane was observed for this sample of Chinese OSA subjects. This study forms the baseline for future studies on the effects of MAD on the airway and craniofacial structures in a larger sample. Key words: Lateral cephalogram, Mandibular advancement splint, Mandibular advancement device, Obstructive sleep apnoea, Polysomnogram

[Influence of oral appliances for obstructive sleep apnea syndrome on stomatognathic system part 1. Occlusion]

PURPOSE

Little information is available on the mandibular protrusion with oral appliances (OA) for the treatment of obstructive sleep apnea syndrome (OSAS) to have no negative effect on the stomatognathic system. The purpose of the current study was to assess the influence of mandibular protrusion on occlusion to fabricate the appropriate OA.

METHODS

Twelve healthy adults were selected. With the OA in position, the mandible was advanced 0, 45, 60, 75% of maximum protrusion capacity; bite raising distance between the first molars was 5mm (OA5-0, 45, 60 and 75). The occlusal force, occlusal contact area and occlusal load center following maximum voluntary clenching for 5 seconds were investigated as follows: after wearing the OA for 1, 3 and 6 hours (Stage A1, A3 and A6) and 1 hour after removal (Stage R1). These data were compared with before wearing (Stage B).

RESULTS

Occlusal force has significant decrement at Stages A1, A3 and A6 after wearing OA5-75, at Stages A3 and A6 after wearing OA5-60, and at Stage A6 after wearing OA5-0. Occlusal contact area has significant decrement at Stages A1, A3 and A6 after wearing OA5-75, and at Stage A6 after wearing OA5-60. Occlusal load center has significant forward displacement at Stages A3 and A6 after wearing OA5-75, and at Stage A6 after wearing OA5-60.

CONCLUSION

To fabricate the appropriate OA in occlusal perspective, it is preferable to set the mandibular position at 45% advancement of maximum protrusion capacity of condyle head in terms of the mandibular positions used in this study.

Autonomic Cardiac Modulation in Obstructive Sleep Apnea

BACKGROUND

Patients with obstructive sleep apnea (OSA) are characterized by deranged cardiovascular variability, a well-established marker of cardiovascular risk. While long-term treatment with continuous positive airway pressure leads to a significant improvement of cardiovascular variability, little is known of the possibility of achieving the same results with other therapeutic approaches. The aim of our study was to investigate the responses of autonomic indexes of neural cardiac control to another type of OSA treatment based on an oral jaw-positioning appliance.

METHODS

In 10 otherwise healthy subjects with OSA (OSA+) and in 10 subjects without OSA (OSA-) we measured heart rate, BP, and indices of autonomic cardiac regulation derived from time-domain and spectral analysis of R-R interval (RRI), before and after 3 months of treatment with the oral device. High-frequency (HF) power of RRI was taken as an index of parasympathetic cardiac modulation, and the ratio between low-frequency (LF) and HF RRI powers as an indirect marker of the balance between sympathetic and parasympathetic cardiac modulation.

RESULTS

At baseline, in comparison with OSA- subjects, OSA+ subjects displayed a significantly lower RRI variance (p < 0.02) and reduced HF RRI powers (p < 0.001). After 3 months of treatment with the oral device, the OSA+ group showed a marked reduction in apnea-hypopnea index (p < 0.001), a lengthening in RRI and a significant increase in its variance (p < 0,02), an increased HF RRI power (from 134 +/- 26 to 502 +/- 48 ms2, p < 0.001), and a reduction in LF/HF RRI power ratio (from 3.11 +/- 0.8 to 1.5 +/- 0.5). As a result of these changes, after the 3-month treatment there were no more significant differences between the two groups in these parameters. In both OSA+ and OSA- groups, body weight, heart rate, and BP did not change over time.

CONCLUSIONS

Three months of treatment with a specific oral jaw-positioning appliance improves cardiac autonomic modulation in otherwise healthy patients with OSA of mild degree.

Oral appliances for obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea-hypopnoea (OSAH) is a syndrome characterised by recurrent episodes of partial or complete upper airway obstruction during sleep that are usually terminated by an arousal. Nasal continuous positive airway pressure (CPAP) is the primary treatment for OSAH , but many patients are unable or unwilling to comply with this treatment. Oral appliances (OA) are an alternative treatment for OSAH.

OBJECTIVES

The objective was to review the effects of OA in the treatment of OSAH in adults.

SEARCH STRATEGY

We searched the Cochrane Airways Group Specialised Register. Searches were current as of June 2005. Reference lists of articles were also searched.

SELECTION CRITERIA

Randomised trials comparing OA with control or other treatments in adults with OSAH .

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed trial quality. Study authors were contacted for missing information.

MAIN RESULTS

Sixteen studies (745 participants) met the inclusion criteria. All the studies had some shortcomings, such as small sample size, under-reporting of methods and data, and lack of blinding. OA versus control appliances (six studies): OA reduced daytime sleepiness in two crossover trials (WMD -1.81;95%CI -2.72 to -0.90), and improved apnoea-hypopnoea index (AHI) (-10.78; 95% CI-15.53 to -6.03 parallel group data - five studies). OA versus CPAP (nine studies): OA were less effective than CPAP in reducing apnoea-hypopnoea index (parallel group studies: WMD 13 (95% CI 7.63 to 18.36), two trials; crossover studies: WMD 7.97; (95% CI 6.38 to 9.56, seven trials). However, no significant difference was observed on symptom scores. CPAP was more effective at improving minimum arterial oxygen saturation during sleep compared with OA. In two small crossover studies, participants preferred OA therapy to CPAP. OA versus corrective upper airway surgery (one study): Symptoms of daytime sleepiness were initially lower with surgery, but this difference disappeared at 12 months. AHI did not differ significantly initially, but did so after 12 months in favour of OA.

AUTHORS' CONCLUSIONS

There is increasing evidence suggesting that OA improves subjective sleepiness and sleep disordered breathing compared with a control. CPAP appears to be more effective in improving sleep disordered breathing than OA. The difference in symptomatic response between these two treatments is not significant, although it is not possible to exclude an effect in favour of either therapy. Until there is more definitive evidence on the effectiveness of OA in relation to CPAP, with regard to symptoms and long-term complications, it would appear to be appropriate to recommend OA therapy to patients with mild symptomatic OSAH, and those patients who are unwilling or unable to tolerate CPAP therapy. Future research should recruit patients with more severe symptoms of sleepiness, to establish whether the response to therapy differs between subgroups in terms of quality of life, symptoms and persistence with usage. Long-term data on cardiovascular health are required.

The effect of a mandibular advancement splint in subjects with sleep-related breathing disorders

OBJECTIVE

This study assessed the effectiveness of a mandibular advancement splint (MAS) in subjects with sleep-related breathing disorders using both objective and subjective outcome measures.

DESIGN

The study was carried out as a retrospective analysis.

SETTING

The study was conducted within the Sleep Studies Unit at the Queen Victoria Hospital, East Grinstead, between May 1997 and March 2000.

SUBJECTS AND METHODS

Twenty subjects with obstructive sleep apnoea (OSA) and six with non-apnoeic snoring, diagnosed by overnight polysomnography, were fitted with a monobloc appliance between May 1997 and March 2000.

MAIN OUTCOME MEASURES

The subjects were analysed for changes in the respiratory disturbance index (RDI) and Epworth Sleepiness Scale (ESS) scores. In addition each subject completed an outcome questionnaire following fitting of the appliance.

RESULTS

Variability in response measured by the change in the respiratory disturbance index was found with no correlation to the baseline recording. Although median RDI values improved in both groups, significantly so in the obstructive sleep apnoea group (p<0.05), seven subjects exhibited an increased RDI score following mandibular advancement splint therapy. The median Epworth Sleepiness Scale scores decreased in both the OSA group and the non-apnoeic snorers although not significantly. Twenty-one of the 26 subjects completed the outcome questionnaire revealing an 81% reduction in snoring. Side-effects were generally transient and minor. Eighty-six per cent of the subjects' partners reported better quality of sleep as a result of MAS therapy.

CONCLUSIONS

The monobloc appliance significantly improved the Respiratory Disturbance Index in the obstructive sleep apnoea group. Some subjects had increased RDI scores following splint therapy. This supports the need for an objective assessment in the follow-up of patients treated with mandibular advancement splints.

Adaptations of Mouthguards for Patients with Special Needs

The adaptations and applications of mouthguard appliances are many and varied, with uses ranging from protective to therapeutic. These modifications serve the individual needs of patients. This requires problem-solving based on combining form and function with the skills of the dentist.

Oral appliances for obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea-hypopnoea is a syndrome characterised by recurrent episodes of partial or complete upper airway obstruction during sleep that are usually terminated by an arousal. Nasal continuous positive airway pressure is the primary treatment for obstructive sleep apnoea-hypopnoea, but many patients are unable or unwilling to comply with this treatment. Oral appliances are an alternative treatment for sleep apnoea.

OBJECTIVES

The objective was to review the effects of oral appliance in the treatment of sleep apnoea in adults.

SEARCH STRATEGY

We searched the Cochrane Airways Group Sleep Apnoea RCT Register. Searches were current as of June 2004. Reference lists of articles were also searched.

SELECTION CRITERIA

Randomised trials comparing oral appliance with control or other treatments in adults with sleep apnoea.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed and two reviewers extracted data independently. Study authors were contacted for missing information.

MAIN RESULTS

Thirteen trials involving 553 participants were included. All the studies had some shortcomings, such as small sample size, under-reporting of methods and data, and lack of blinding. Oral appliances versus control appliances (five studies): Oral appliances reduced daytime sleepiness in two crossover trials (WMD -1.81 [95%CI: -2.72, -0.90]), and improved apnoea-hypopnoea index (AHI) (-13.17 [-18.53 to -7.80] parallel group data - four studies). Oral appliances versus CPAP (seven studies): Oral appliances were less effective than continuous positive pressure in reducing apnoea-hypopnoea index (WMD 13 [95% CI: 7.63, 18.36], parallel studies - two trials; WMD 6.96 [4.82, 9.10] cross-over studies - six trials). However, no significant difference was observed on symptom scores. Nasal continuous positive pressure was more effective at improving minimum arterial oxygen saturation during sleep compared with oral appliance. In two small crossover studies, participants preferred oral appliance therapy to continuous positive airways pressure. Oral appliances versus surgery (one study): Symptoms of daytime sleepiness were initially lower with surgery, but this difference disappeared at 12 months. AHI did not differ significantly initially, but did so after 12 months in favour of OA.

REVIEWERS' CONCLUSIONS

There is some evidence suggesting that oral appliance improves subjective sleepiness and sleep disordered breathing compared with a control. Nasal continuous positive airways pressure appears to be more effective in improving sleep disordered breathing than oral appliance. Until there is more definitive evidence on the effectiveness of oral appliances, it would appear to be appropriate to restrict oral appliance therapy to patients with sleep apnoea who are unwilling or unable to comply with continuous positive airways pressure therapy.

Efficacy and co-morbidity of oral appliances in the treatment of obstructive sleep apnea-hypopnea: a systematic review

The Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) is a common sleep-related breathing disorder characterized by repetitive obstructions of the upper airway during sleep. Modification of pharyngeal patency by Oral Appliance (OA) therapy has been suggested as an alternative to various treatment modalities for OSAHS. To determine the evidence base with respect to the efficacy and co-morbidity of OA therapy in OSAHS, we conducted a systematic review of the available literature. Primary outcome measures were the reduction in number of upper-airway obstructions and co-morbidity related to the craniomandibular or craniofacial complex, respectively. Eligible studies regarding efficacy were independently assessed by two assessors using a quality assessment scale. Effect sizes of methodologically sound studies were calculated. In identical interventions, effect sizes were pooled with the use of a random-effects model. Given the scarcity of controlled studies related to co-morbidity, appraisal was confined to a description of eligible studies. Sixteen controlled trials related to efficacy were identified. With respect to the primary outcome measure, OA therapy was clearly more effective than control therapy (pooled effect size, -0.96; 95% confidence interval [CI], -1.49 to -0.42) and possibly more effective than uvulopalatopharyngoplasty. Although patients generally preferred OA therapy, improvement of respiratory variables, such as the number of upper-airway obstructions, was usually better in Continuous Positive Airway Pressure (CPAP) therapy (pooled effect size, 0.83; 95% CI, 0.59 to 1.06). Moreover, specific aspects related to OA design may influence patient-perceived efficacy and preference. Twelve patient-series and one controlled trial related to co-morbidity were identified. Analysis of the data suggests that OA therapy may have adverse effects on the craniomandibular and craniofacial complex. Although CPAP is apparently more effective and adverse effects of OA treatment have been described, it can be concluded that OA therapy is a viable treatment for, especially, mild to moderate OSAHS. Controlled studies addressing the specific indication and co-morbidity of OA therapy are warranted.

Effect of titrated mandibular advancement and jaw opening on the upper airway in nonapneic men: a magnetic resonance imaging and cephalometric study

The aim of this study was to examine adaptive changes in the cross-sectional area of the upper airway during mandibular advancement and jaw opening and to explore whether these changes are directly related to morphologic features of the mandible. Fourteen nonapneic men participated in this study. A custom-made oral device was used to keep the mandible at 0% (F(0)V(0)), 50% (F(50)V(0)), 75% (F(75)V(0)), or 100% (F(100)V(0)) of maximum advancement, and at 50% (F(75)V(50)), 75% (F(75)V(75)), or 100% (F(75)V(100)) of maximum gape at F(75)V(0). Magnetic resonance imaging was used to investigate differences in the upper-airway cross-sectional area in these 7 positions. To eliminate excessive individual variation, changes in the mean (mean%) and minimum (min%) cross-sectional area of the upper airway were calculated as percentages of those at F(0)V(0). Cephalograms were taken to analyze morphologic features of the mandible. A dose-dependent change was seen when the mandible was advanced. The min% in F(100)V(0) was significantly greater than those in F(50)V(0) and F(75)V(0). The change in the upper airway size varied between subjects during jaw opening. At F(75)V(0), the min% of the whole upper airway was significantly associated with morphologic features of the mandible, such as the mandibular plane angle and lengths of the mandibular body and ramus.

The role of oral appliance therapy in the treatment of obstructive sleep apnea

The development of oral appliance treatment for OSA represents an important step in the management of this disease. Randomized, controlled clinical trials have shown them to be an effective treatment option for snoring and OSA in some patients, particularly patients with less severe OSA or simple snoring and patients who have failed other treatment modalities. Although oral appliances are not as effective as CPAP therapy, they work in most patients to relieve symptoms and apnea and are well tolerated by patients. Most patients report improvements in sleep quality and excessive daytime sleepiness. Short-term side effects are generally minor and are related to excessive salivation, jaw and tooth discomfort, and occasional joint discomfort. These symptoms may lead to discontinuation of appliance therapy but usually improve in most patients over time. Serious complications are not common, but occlusal changes are more common than previously believed.