Forces created by mandibular advancement devices in OSAS patients

Effects of Oral Appliances for Obstructive Sleep Apnoea in Reduced Periodontium: A Finite Element Analysis

BACKGROUND AND OBJECTIVE

In the literature, no studies correlate the effects of mandibular advancement devices (MADs) with different titration systems to periodontitis. Through a finite element analysis (FEA), this study investigates the effects generated on periodontal ligaments (PDLs) and teeth by four commercial MADs in periodontal health and with 15% bone resorption.

METHODS

Four MADs (Somnodent Flex™, Somnodent Avant™, Orthoapnea™, and Herbst™) were digitalised starting from the impressions of a patient's dental arches. A force of 11.18 N, representing an advancement of 9.5 mm, was applied, and a FEA was subsequently performed. After measuring the stresses and displacements on the PDLs and teeth in healthy periodontal conditions, the vertical dimension of the alveolar bone was reduced by 15%, and measurements were repeated.

RESULTS

In terms of PDL stress, Herbst™ is the device which guarantees a more uniform increment in case of the first stage of periodontitis (+7% for mandibular and maxillary PDLs compared to the healthy condition). For Somnodent™ devices, the PDLs stress increment is almost null for mandibular PDLs but much higher than Herbst™ for maxillary PDLs (+17% and +21% for Flex™ and Avant™). Orthoapnea™ determines a PDL stress augmentation between the other devices (+16% and +7%, respectively, for maxillary and mandibular PDLs). Concerning teeth movement, Herbst™ and Orthoapnea™ determine a lower and more uniform displacement than Somnodent devices.

CONCLUSIONS

The stress distribution and teeth displacement are strictly related to MAD geometry. Since its minor effects on teeth and PDLs, the Herbst™ could be more appropriate in patients with periodontitis.

Smart mandibular advancement devices for obstructive sleep apnea: a systematic literature review

PURPOSE

The goal of this review is to provide sleep physicians, dentists, and researchers with an evidence-based overview of the literature on smart mandibular advancement devices (MADs) for the treatment of obstructive sleep apnea.

METHODS

A systematic literature search was conducted by two blinded reviewers and an information specialist. A smart MAD was defined as any MAD with additional functionality besides mandibular protrusion. The bibliographic databases Medline, Embase, and Scopus were used to identify relevant publications. Studies were included if they described any stage of development of smart MADs. A total of 3162 titles and abstracts were screened for their relevance. In total, 58 articles were selected for full-text screening, 26 of which were included in this review.

RESULTS

The overall quality of the available literature was low. Most of the studies were observational, clinical or applied-research articles. The authors classified MADs into two main groups: passive and active. Passive MADs measured patient data, most commonly patient compliance. Active MADs adjusted protrusion of the mandible in response to patient data and were found in various phases of technological readiness (in development, demonstration, or deployment).

CONCLUSION

Innovations in smart mandibular advancement devices most frequently track patient compliance. Devices measuring other health parameters and active, feedback-controlled, devices are increasingly reported on. However, studies demonstrating their added benefit over traditional methods remain sparse. With further study, smart mandibular advancement devices have the potential to improve the efficiency of obstructive sleep apnea treatment and provide new treatment possibilities.

Sleep and periodontal health

Sleep is fundamental for health and well-being. An adequate amount and quality of sleep is a cardinal component of a healthy lifestyle at the basis of the prevention of many non-communicable chronic diseases. Recent evidence suggests that sleep disorders, particularly obstructive sleep apnea, represent an emerging risk factor for periodontal health. This review article provides a critical appraisal of the existing literature concerning the association between sleep duration, sleep quality, sleep disorders in general, and obstructive sleep apnea with periodontal diseases, including gingivitis and periodontitis. The putative mechanisms underlying these associations are described as well as the potential clinical implications for diagnosis and treatment.

Periodontal effects of two Somnodent oral devices for the treatment of OSA: A finite element study

OBJECTIVE

The study aims to evaluate the stresses and the deformations generated at the periodontal level by two mandibular advancement devices (MADs) using finite element analysis.

METHODS

A three-dimensional digital model of the skull of a 29-year-old patient was created using a CBCT. The 3D models of two MADs (Somnodent FlexTM and Somnodent AvantTM) were reconstructed from scanning prototypes based on the patient's anatomy. The overall geometry was imported into software for the finite element study. A force of 11.18 N representing an advancement of 9.5 mm was applied to the devices. A finite element analysis wfas subsequently performed.

RESULTS

Somnodent FlexTM generates a peak of 3.27 kPa on periodontal ligaments and 287 kPa on teeth. For Somnodent AvantTM the maximum stress is 4.53 kPa on periodontal ligaments and 467 kPa on teeth.

CONCLUSION

Different activation mechanisms of the devices generate stresses of different entities.

Objectively measured adherence may affect side effects of mandibular advancement therapy in subjects with obstructive sleep apnea

PURPOSE

The purpose of this study was to determine if objectively measured adherence to oral appliance (OA) treatment may affect dental changes and temporomandibular disorders (TMD) in patients with obstructive sleep apnea (OSA).

METHODS

The original study group consisted of adults with OSA who were referred for OA therapy. Eight indicators of subjective side effects of using OA (temporomandibular joint (TMJ) and muscle pain, pain in teeth, jaw stiffness in the morning, clicking, dry mouth, hypersalivation, gingival irritation) were evaluated by a questionnaire. Three occlusal indicators (overjet, overbite, molar occlusion) and clinical TMD signs (TMJ pain, muscle pain, clicking, jaw deviation on opening) were evaluated at baseline and at the 3-, 6-, and 12-month follow-up. In addition, objective adherence monitoring for OA was registered. Statistical analyses included the chi-square test, Fisher's exact test, paired sample t-test, and linear regression analyses.

RESULTS

A total of 58 adults with OSA were referred for OA therapy. Mean (SD) age was 50.7 (11.7) and mean apnea-hypopnea index (AHI) was 19.5 (10.0). At 1-year follow-up, the study group consisted of 28 men and 12 women. Overjet but not overbite reduced significantly after 1-year OA therapy. The average nightly wear of OA was related to overjet and overbite reduction, and to TMD signs. Hypersalivation, dry mouth, and tooth discomfort were the most common subjective side effects of OA therapy.

CONCLUSION

There was a time-dependent relationship with the nightly wear of OA and reduction in overjet and overbite, and clinical TMD signs. With 60% of mandibular advancement, dental changes and TM-disorders were considered mild/minor in the 1-year study period.

A Multicenter Prospective Study on the Use of a Mandibular Advancement Device in the Treatment of Obstructive Sleep Apnea

The main objective of this prospective study was the evaluation of 1 mm step titration of mandible advancement in the success of treating obstructive sleep apnea (OSA). For that, a multicenter prospective study was designed to recruit patients with OSA who were eligible to receive a mandibular advancement device. Gradual titration of mandibular advancement (steps of 1 mm) from maximum intercuspidation was performed to determine the optimal mandibular advancement (highest reduction in the apnea-hypopnea index (AHI)). The principal variable was the percentage of patients where a reduction ≥50% of the AHI was achieved at the end of the titration phase. A total of 102 patients participated in this study. Fifty-six percent of the participants were males and 67% had a BMI ≥ 25 kg/m2. Most of the patients (79%) had an age ≥ 50 years and the majority (74%) were either non-smokers or ex-smokers. Excessive daytime sleepiness was reported by 40% of the patients. The mean AHI at baseline was 20.6 ± 12.7 events/h. The mean advancement of the mandible was 3.1 ± 1.6 mm. The device achieved a reduction in the AHI in 93% of the patients and success (≥50% reduction in the AHI) in 69% of the patients. Success was achieved in 50%, 81.6%, and 73.3% of the patients with mild, moderate, and severe OSA, respectively. Decreasing the magnitude of mandibular advancement could be possible by controlling the vertical mouth opening and step-by-step titration.

Mandibular advancement devices used with morning occlusal guides for treating obstructive sleep apnea-changed incisor inclination and its associated factors

PURPOSE

Mandibular advancement devices (MADs) effectively treat patients with obstructive sleep apnea (OSA). Although the use of morning occlusal guides (MOGs) along with MADs is recommended to prevent dental side effects, there is no evidence to support this. The aim of this study was to evaluate the change in incisor inclination in patients with OSA treated with MADs and MOGs, and to identify its predictive factors.

METHODS

Patients with OSA who received MAD and MOG therapy and had a reduction in their apnea-hypopnea index greater than 50% were analyzed. Cephalometric measurements were performed at baseline and at a 1-year follow-up or longer to assess the dentoskeletal side effects of MAD/MOG treatment. Multivariable linear regression analysis was used to assess the association between the change in incisor inclination and the independent variables that may cause the observed side effects.

RESULTS

Among 23 patients enrolled in the study, there was significant upper incisor retroclination (U1-SN: 2.83° ± 2.68°, U1-PP: 2.86° ± 2.46°; P < 0.05) and significant lower incisor proclination (L1-SN: 3.04° ± 3.29°, L1-MP: 1.74° ± 3.13°; P < 0.05). However, no significant skeletal changes were observed. Multivariable linear regression revealed that advancement ≥ 95% of the patients' maximal mandibular protrusion was associated with greater upper incisor retroclination. Increased treatment duration was also associated with increased upper incisor retroclination. No \measured variables were associated with the change in lower incisor inclination.

CONCLUSIONS

Dental side effects occurred in patients who used MADs with MOGs. The amount of mandibular protrusion by MADs and treatment duration were predictive factors associated with upper incisor retroclination.

Oral appliance-generated malocclusion traits during the long-term management of obstructive sleep apnea in adults

OBJECTIVES

To identify malocclusion characteristics generated after using oral appliances (OAs) for at least 5 years for the management of snoring and obstructive sleep apnea (OSA) in adults.

MATERIALS AND METHODS

PubMed, MEDLINE (Ovid), Scopus, CINAHL, and Informit were searched without language restrictions through January 20, 2021. Unpublished literature was searched on ClinicalTrials.gov, the National Research Register, and the Pro-Quest Dissertation Abstracts and Thesis database. Authors were contacted when necessary, and reference lists of the included studies were screened. Risk of bias was assessed through the revised Cochrane Risk of Bias tool for randomized controlled trials (RoB2) and Non-Randomized Studies of Interventions for non-RCTs and uncontrolled before-after studies (ROBINS-I). A random-effects meta-analysis was conducted only on studies that used the same OAs to exclude biomechanical differences. Risk of bias across studies was assessed with the Grading of Recommendations, Assessment, Development and Evaluation tool.

RESULTS

A total of 12 studies were included in the final qualitative synthesis. Eight included studies had high, one had moderate, and three had low risks of bias. Significant progressive decreases of overjet (OJ; -1.43 mm; 95% confidence interval [CI], -1.66 to -1.20) and overbite (OB; -1.94 mm; 95% CI, -2.14 to -1.74) associated with maxillary incisor retroclination and mandibular incisor proclination were reported long term. Although most studies showed no sagittal skeletal changes, some degree of vertical skeletal changes were noted.

CONCLUSIONS

Based on a very low evidence level, inevitable anterior teeth positional changes seem to be a common long-term adverse effect of OAs. The magnitude of those changes could be considered clinically irrelevant for most pretreatment occlusions, but in occlusions with limited OJ and OB, it may be worth clinical consideration.

The effect of gradually increased mandibular advancement on the efficacy of an oral appliance in the treatment of obstructive sleep apnea

STUDY OBJECTIVES

To analyze the effect of gradual increments of mandibular advancement on the treatment efficacy of mandibular advancement devices and identify determinants of effective and target protrusion for OSA.

METHODS

Patients were prospectively recruited. The mandible was titrated from 0 mm with a stepwise increment of 0.5 mm until the AHI was reduced to the lowest level. Rhinospirometry, rhinomanometry, and magnetic resonance imaging were used to observe the change of respiratory function and upper airway morphology.

RESULTS

Forty-two patients aged 41.5 ± 9.0 years participated. There was a dose-dependent relationship between mandibular protrusion and the AHI improvement rate, the success rate, and the normalization rate; the changing curves plateaued after approximately 70% of maximal mandibular protrusion was achieved. The correlation between AHI and mandibular protrusion became stronger as the severity of OSA increased. The target protrusion for patients with mild, moderate, and severe OSA was 3.5 ± 1.8 mm (38.6 ± 19.4% maximal mandibular protrusion), 5.8 ± 1.9 mm (62.9 ± 18.8% maximal mandibular protrusion), and 5.9 ± 2.2 mm (68.8 ± 15.6% maximal mandibular protrusion), respectively. Regression analysis revealed that the factors influencing effective and target protrusion included change of maximal lateral dimension of the total upper airway with mandibular advancement devices, mean lateral dimension of the oropharynx, and soft palate length. Further protrusion brought more lateral expansion of the velopharynx, whereas the change in nasal ventilation was not significant.

CONCLUSIONS

The dose-dependent effect of mandibular protrusion on reduction of AHI by mandibular advancement devices was nonlinear and became more pronounced with increased severity of OSA. The mandibular protrusion should be more personalized to each patient.

CLINICAL TRIAL REGISTRATION

Registry: Chinese Clinical Trial Registry; Name: Study of the Onset Point of Oral Appliance Treatment in Obstructive Sleep Apnea and Hypopnea Syndrome; URL: http://www.chictr.org.cn/showproj.aspx?proj=22291; Identifier: ChiCTR-IND-17013232.

Force Distribution of a Novel Core-Reinforced Multilayered Mandibular Advancement Device

A mandibular advancement device (MAD) is a commonly used treatment modality for patients with mild-to-moderate obstructive sleep apnea. Although MADs have excellent therapeutic efficacy, dental side effects were observed with long-term use of MADs. The aim of this study was to analyze the force distribution on the entire dentition according to the materials and design of the MADs. Three types of MADs were applied: model 1 (single layer of polyethylene terephthalate glycol (PETG)), model 2 (double layer of PETG + thermoplastic polyurethane (TPU)), and model 3 (core-reinforced multilayer). In the maxilla, regardless of the model, the incisors showed the lowest force distribution. In most tooth positions, the force distribution was lower in models 2 and 3 than in model 1. In the mandible, the mandibular second molar showed a significantly lower force in all models. The mandibular incisors, canines, and molars showed the highest force values in model 1 and the lowest values in model 3. Depending on the material and design of the device, the biomechanical effect on the dentition varies, and the core-reinforced multilayered MAD can reduce the force delivered to the dentition more effectively than the conventional single- or double-layer devices.

A finite element analysis for evaluating mandibular advancement devices

Obstructive sleep apnoea (OSA) is a disorder characterised by complete or partial occlusion of the upper airway during sleep. Muscles relax during sleeping and collapse into the airway, closing the throat and prohibiting air flowing into the lungs. Different solutions have been adopted to manage the pathology to improve the life quality of affected patients. Mandibular advancement devices (MADs) are proven to be a compliant and successful therapy in the forward repositioning of the mandible to increase the upper airway volume. However, this method has some long-term adverse events that may affect the teeth and periodontal ligaments. This paper presents a finite element model to evaluate the MADs effects (displacement and stress) on teeth and periodontal ligaments, by varying the design, the point of application of the force and the material. The modelled bodies have been reconstructed through a Reverse Engineering approach and computer-aided design tools starting from tomographic images of anatomic bodies and from laser scans of a physical MAD. The results suggest that a central connection mechanism could affect mostly the anterior teeth. In contrast, a lateral connection mechanism provides a more uniform distribution of the load on teeth.

Avoiding and Managing Oral Appliance Therapy Side Effects

There is a serious need to consider all potential side effects thoughtfully before commencing individual treatment with oral appliance therapy. Although many of these side effects are self-limiting, easily corrected, or innocuous, others are difficult or impossible to correct and can affect the patient in serious ways. As this field evolves, new information is discovered, and new products are introduced at a rather rapid pace, continuing education and prudent practice are critical to ethical care in the practice of dental sleep medicine.

Maximum voluntary retrusion or habitual bite position for mandibular advancement assessment in the treatment of obstructive sleep apnoea patients

BACKGROUND

There is no consensus on whether the range of mandibular advancement for the construction of mandibular advancement devices in obstructive sleep apnoea (OSA) patients should be measured from a starting position of maximum voluntary retrusion or habitual bite position.

OBJECTIVE

The purposes of this study were to investigate the differences in mandibular advancement registrations starting from maximum voluntary retrusion or from habitual bite position and to evaluate the reliability of these assessments.

METHODS

A retrospective cohort analysis of 126 patients with OSA was performed. All patients had their mandibular range of motion evaluated twice (starting from maximum voluntary retrusion and from habitual bite position) through the George Gauge before undergoing drug-induced sleep endoscopy. The Dahlberg formula and paired t test were used to calculate random and systematic errors of dental positions assessment. Test-retest reliability was quantified using the intra-class correlation coefficient (ICC).

RESULTS

The mean mandibular range starting from maximum voluntary retrusion and from habitual bite position were 12.49 ± 2.19 mm and 7.68 ± 2.29 mm, respectively, with a mean distance between the two starting positions of 4.81 ± 1.75 mm. No systematic error was found (P > .05), and random errors ranged from 0.30 to 0.95 mm. ICC values were excellent for maximum voluntary protrusion (ICC = 0.986) and maximum voluntary retrusion (ICC = 0.956), whereas habitual bite position showed a good value (ICC = 0.818).

CONCLUSION

The difference between maximum voluntary retrusion and habitual bite position is potentially relevant. Maximum retrusion is advisable as starting point of the mandibular advancement registration since it provides a more reliable measure.

High-Resolution Pulse Oximetry and Titration of a Mandibular Advancement Device for Obstructive Sleep Apnea

Background: To determine whether utilizing high-resolution pulse oximetry is a viable method for evaluating the successful titration of oral appliances for the treatment of obstructive sleep apnea (OSA) patients.

Methods: Of 136 consecutive potentially eligible OSA patients, 133 were fitted with mandibular advancement devices (MADs), and 101 completed all phases of treatment. The vertical and horizontal dimensions of the appliances were adjusted based on three-nights with a high-resolution pulse oximeter during sleep and associated software after each adjustment.

Results: Significant improvements in OSA severity were apparent in patients at all disease severity levels. High-resolution pulse oximetry provided reliable guidance in the titration process of mandibular advancement therapy. In 67 subjects (66.3%), a respiratory event index of <5 events/hour was achieved.

Conclusions: OSA can be effectively treated with a MAD at any severity level, and high-resolution pulse oximetry provides critical information to guide oral appliance titration.

Subjective versus objective dental side effects from oral sleep apnea appliances

Purpose

Occlusal changes are common during long-term treatment with oral appliances (OAs) for sleep apnea. The aim of the present study was to compare subjectively reported bite changes with objective findings.

Methods

Consecutive adherent treated patients were asked to participate in this study. The patients responded to two questionnaires using numeric visual analogue scales (VAS), ranging from 0 (not at all) to 10 (very much). The first questionnaire included open questions and the second questionnaire comprised specific questions about side effects. Measurements of overjet, overbite, and space for the teeth were made on plaster casts taken before treatment start and at follow-up.

Results

Thirty-eight (12 women) patients with a median age of 64 years (interquartile range (IQR) 57 to 69 years) and a median treatment time of 9.5 years (IQR 5.8 to 14.3 years) were included. Overjet, overbite, the molar relationship, and the irregularity of the lower front teeth had changed significantly during treatment. There were no associations between any of the patients’ responses and the objectively measured bite changes. Younger patients, those with a small baseline overjet or overbite and those who developed an anterior crossbite were more likely to report bite changes.

Conclusions

Patients who choose to continue long-term treatment with oral appliances for sleep apnea are unaware of various types of bite changes. Such changes will, however, progressively increase in magnitude and be more difficult to take care of, if needed. It is therefore important continuously to follow up patients in regard to bite changes.

Dentoskeletal effects of oral appliance wear in obstructive sleep apnoea and snoring patients

Objectives

To evaluate the dentoskeletal changes associated with long-term and continuous mandibular advancement device (MAD) use in sleep-related breathing disorder patients.

Methods

Cephalometric measurements and three-dimensional model analysis were performed at baseline and after 3.5 ± 1.1 years in 20 snoring and obstructive sleep apnoea patients treated with the Silensor® appliance. Intra-group differences were compared using paired t-test or Wilcoxon signed-rank test. A regression analysis was performed for variables that showed a statistically significant difference between time points to evaluate the influence of treatment time and patient's initial characteristics on their variations. The statistical significance was set at P < 0.05.

Results

At cephalometric assessment, the maxilla revealed a significant decrease in horizontal position (SNA: -0.4 ± 0.72 degree, P = 0.021) and a significant retroclination of the upper incisor (-1.59 ± 1.07 degree, P < 0.001), while the mandible displayed a significant downward rotation (0.88 ± 1.28 degree, P = 0.006) and a proclination of the lower incisor (2.27 ± 1.38 degree, P < 0.001). Model analysis showed a decrease in upper total space discrepancy (-0.66 ± 0.72 mm, P < 0.002), overjet (OJ; -0.34 ± 0.47 mm, P < 0.011), and overbite (-0.4 ± 0.52 mm, P < 0.004). In the regression analysis, treatment time influenced the lower incisor inclination (Beta = -0.713, P = 0.018) and OJ (Beta = -0.218, P = 0.018); patients' initial characteristics had an effect on OJ (Beta = -0.195, P = 0.011).

Limitations

A larger sample size could increase the generalizability of the findings.

Conclusion

MAD wear after a mean of 3.5 years determines statistically significant but clinically irrelevant dentoskeletal changes. Their potential occurrence should be thoroughly discussed with patients; regular follow-up visits by a specialist experienced in dental sleep medicine are also mandatory during treatment in addition to polysomnographic examinations.

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.

Avoiding and Managing Oral Appliance Therapy Side Effects

There is a serious need to consider all potential side effects thoughtfully before commencing individual treatment with oral appliance therapy. Although many of these side effects are self-limiting, easily corrected, or innocuous, others are difficult or impossible to correct and can affect the patient in serious ways. As this field evolves, new information is discovered, and new products are introduced at a rather rapid pace, continuing education and prudent practice are critical to ethical care in the practice of dental sleep medicine.

Side effects of mandibular advancement splints for the treatment of snoring and obstructive sleep apnea: a systematic review

INTRODUCTION

Occlusal side effects or development of pain and/or functional impairment of the temporomandibular complex are potential reasons for poor compliance or abandonment of mandibular advancement splints treatment for snoring and obstructive sleep apnea.

OBJECTIVE

This study aimed at providing a comprehensive review evaluating the craniofacial side effects of oral appliance therapy for snoring and obstructive sleep apnea.

METHODS

An electronic search was systematically conducted in PubMed and Virtual Health Library from their inception until October 2016. Only Randomized Controlled Trials whose primary aim was to measure objectively identified side effects on craniofacial complex of a custom-made oral appliance for treating primary snoring or obstructive sleep apnea were included. Studied patients should be aged 20 or older. The risk of bias in the trials was assessed in accordance with the recommendations of The Cochrane Risk of Bias criteria.

RESULTS

A total of 62 full-text articles were assessed for eligibility. After the review process, only 6 met all the inclusion criteria. All studies were rated as having a high risk of bias. The most uniformly reported mandibular advancement splint side effects were predominantly of dental nature and included a decrease in overjet and overbite. The risk of developing pain and function impairment of the temporomandibular complex appeared limited with long-term mandibular advancement splint use.

CONCLUSION

The limited available evidence suggests that mandibular advancement splint therapy for snoring and obstructive sleep apnea results in changes in craniofacial morphology that are predominantly dental in nature, specially on a long-term basis. Considering the chronic nature of obstructive sleep apnea and that oral appliance use might be a lifelong treatment, a thorough customized follow-up should therefore be undertaken to detect possible side effects on craniofacial complex. It is also important to provide adequate information to the patients regarding these possible changes, especially to those in whom larger occlusal changes are to be expected or in whom they are unfavorable. Long-term assessments of adverse effects of oral appliance therapy, with larger study samples and recruitment of homogenous patient population are still required.

The role of masseter muscle EMG during DISE to predict the effectiveness of MAD: preliminary results

The use of a mandibular advancement device (MAD) increases the activity of the temporo-mandibular (TM) complex and masseter (MM) muscles with the risk of reducing treatment compliance. Predictors of treatment outcome are of importance in selecting patients who might benefit from MAD without side effects. The role of mandibular advancement (MA) during drug-induced sleep endoscopy (DISE) is controversial. In three cases (BMI < 30) affected by non-severe OSAS (AHI < 30 e/h), we recorded the surface EMG signal of MM activity during DISE. At follow-up all cases improved the AHI, two cases that showed transient increase of MM activity did not suffer from changes of overjet and did not complain of discomfort with the use of MAD. The case that showed a continuing increase of MM activity reported TM discomfort without changes of dental occlusion. EMG of MM during DISE may contribute to ameliorate the selection of cases amenable to treatment with MAD.

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.

Update on Oral Appliance Therapy for OSA

Purpose of Review

The majority of the adult population is affected by obstructive sleep apnea (OSA), according to recent epidemiological research. Oral appliance (OA) therapy is increasingly recommended, particularly for patients with milder OSA. This review updates the evidence in favor of OA therapy.

Recent Findings

A high level of evidence shows that OA is effective in the treatment of OSA, but continuous positive airway pressure (CPAP) is more efficient. Higher adherence with OAs may compensate for this difference. Daytime sleepiness is better treated with CPAP than with OA in patients with severe OSA. In patients with milder OSA, it is unclear whether sleepiness is significantly reduced. The long-term effectiveness of OAs is uncertain because of side-effects and the risk of OSA deterioration.

Summary

OAs are effective, but their efficacy is more variable than that of CPAP. More research is needed about the mechanism of action of OA, subjective effects and long-term health outcomes.

Changes in lower incisor irregularity during treatment with oral sleep apnea appliances

PURPOSE

The purpose of this study is to test the hypothesis that a flexible oral appliance without incisor coverage (OA_Flex) increases the irregularity of the front teeth compared with a rigid appliance with incisor coverage (OA_Rigid) in patients treated for obstructive sleep apnea (OSA).

METHOD AND PATIENTS

Nineteen patients (10 men) who had used OA_Rigid and 22 patients (19 men) who had used OA_Flex with a median age of 61 years (IQR of 56 to 67 years) who had been treated during a median period of 2.9 years (IQR of 2.7 to 3.1 years) were included in the study. There was no difference in age (p = 0.601) or treatment time (p = 0.432) between the two appliance groups. The patients had clinical examinations, responded to a questionnaire, and had impressions taken for plaster casts. The irregularity of the front teeth was measured by Little's Index, where the combined linear displacement of all the front teeth is assessed. Changes between baseline and follow-up were compared between the two groups.

RESULTS

The OA_Flex group increased the irregularity of their lower front teeth by 0.3 mm (p = 0.018), while the OA_Rigid group had unchanged frontal irregularity (p = 0.717). The difference between the groups was significant (p = 0.035). There were no changes in the irregularity of the upper front teeth in either group. Patient satisfaction with treatment did not differ between the two appliances.

CONCLUSIONS

The present results support the hypothesis that a flexible OA without incisor coverage increases the irregularity of the lower front teeth compared with a rigid OA with incisor coverage.

Influence of Oral Appliances for Mandibular Advancement on Dentitions Using a Strain Gauge Analysis: A Pilot Study

Introduction. This study aimed to evaluate the influence of oral appliances (OAs) on dentition using a strain gauge analysis. Materials/Methods. Eight volunteers, who were mild snorers, participated in this study. OAs were individually constructed, and advancement was defined as two-thirds of the maximum mandibular advancement. Strain gauges were mounted on the right first molar and central incisor of both the upper and lower arches. After OA use, two measurement sessions (short- and long-term) were performed. Results. Compressive strain on the labial surface was significantly larger than the stretching strain on the lingual surface on U1. On L1, the stretching strain on the labial surface was significantly larger than the compressive strain on the lingual surface. Comparing the upper and lower teeth, the stretching strain was significantly greater on L1 than on U1 in both test sessions. Moreover, the stretching strain was significantly larger on U6 than on L6. Conclusion. OA side effects, such as forcing on the incisors, might be repeated every night. In this way, permanent occlusal changes, such as labial tipping of L1, may occur, followed by lingual tipping of U1 and buccal and lingual movements of the U6 and L6, respectively.

Obstructive sleep apnea and mandibular advancement splints: occlusal effects and progression of changes associated with a decade of treatment

STUDY OBJECTIVES

To evaluate the magnitude and progression of dental changes associated with long-term mandibular advancement splint (MAS) treatment of obstructive sleep apnea (OSA).

METHODS

Retrospective study of adults treated for primary snoring or mild to severe OSA with MAS for a minimum of 8 years. The series of dental casts of patients were analyzed with a digital caliper for changes in overbite, overjet, dental arch crowding and width, and inter-arch relationships. The progression of these changes over time was determined and initial patient and dental characteristics were evaluated as predictors of the observed dental side effects of treatment.

RESULTS

A total of 77 patients (average age at start of treatment: 47.5 ± 10.2 years, 62 males) were included in this study. The average treatment length was 11.1 ± 2.8 years. Over the total treatment interval evaluated there was a significant (p < 0.001) reduction in the overbite (2.3 ± 1.6 mm), overjet (1.9 ± 1.9 mm), and mandibular crowding (1.3 ± 1.8 mm). A corresponding significant (p < 0.001) increase of mandibular intercanine (0.7 ± 1.5 mm) and intermolar (1.1 ± 1.4 mm) width as well as incidence of anterior crossbite and posterior open bite was observed. Overbite and mandibular intermolar distance were observed to decrease less with time, while overjet, mandibular intercanine distance, and lower arch crowding all decreased continuously at a constant rate.

CONCLUSIONS

After an average observation period of over 11 years, clinically significant changes in occlusion were observed and were progressive in nature. Rather than reaching a discernible end-point, the dental side effects of MAS therapy continue with ongoing MAS use.

COMMENTARY

A commentary on this article appears in this issue on page 1293.

Retention of mandibular advancement devices in the treatment of obstructive sleep apnea: an in vitro pilot study

Purpose

In order for a mandibular advancement device (MAD) to be efficacious, it must remain seated on the teeth during sleep. Quantitative data on the retentive characteristics of MADs are currently unavailable. The present pilot study is the first to describe an in vitro setup testing the retentive characteristics of different monobloc MADs.

Methods

A hydraulic cyclic test machine was used with MADs seated on dental casts to measure retention forces upon removal of the MADs. A custom-made monobloc (CM-mono), a thermoplastic monobloc (TP-mono), and a thermoplastic duobloc (TP-duo) configured as a monobloc were tested. Two protrusions were investigated, representing 25 and 65 % of the maximal protrusion. The effects of the type of MAD, duration of the test, and amount of protrusion on removal forces were measured.

Results

The measured removal forces of all three MADs tested differed significantly, with the TP-duo showing the highest values (P < 0.0001). The effects of wear due to the repetitive cyclic loading became obvious by the production of wear particles in all MADs tested. However, only the TP-duo showed a significant reduction in time in removal forces for both protrusion positions (P < 0.0001; P = 0.0011). The effect of the amount of protrusion on the removal forces differed significantly between all three MADs tested (P = 0.0074).

Conclusions

This in vitro pilot study reveals significant differences in retention forces for the MADs tested. The findings are consistent with clinical effects of nightly loss of MADs as reported in the literature and are within the range of reported physiological mouth-opening forces. Future research is needed to determine the key design features of MADs that explain these differences.

The use of a mandibular repositioning device for obstructive sleep apnea

The objective of this study was to verify the effect of a mandibular repositioning device (MRD) on polysomnographic parameters and on the mean electromyographic activity of the masseter and temporal muscles in individuals with obstructive sleep apnea syndrome (OSAS). This is a prospective cohort study conducted at multidisciplinary OSAS center in a tertiary referral center. Nineteen individuals with mild or moderate OSAS associated with Mallampati 3-4 were treated with an MRD during sleep. The subjects underwent diurnal electromyography (EM) and nocturnal polysomnography (PSG) examinations both prior and after initial treatment (3 months with MRD for PSG and 6 and 12 months of treatment for EM). The examinations performed at different times were compared. Comparison of the initial and final polysomnography examination revealed a significant mean reduction of apnea-hypopnea index (AHI) from 13.8 to 7.8. The successful treatment rate with the MRD was 52.6%, and the improved treatment rate was 68.4%. Patients with lower pre-treatment AHI presented higher rates of cure. There was no statistically significant change in electromyography examination among different times. The MRD reduced the apnea-hypopnea index in individuals with enlarged base of tongue and mild and moderate OSAS without damaging the function of the masseter and temporal muscles as determined by electromyography.