Scientific investigations The Tongue-Retaining Device: Efficacy and Side Effects in Obstructive Sleep Apnea Syndrome Diane S. Lazard, M.D. 1 ; Marc Blumen, M.D. 2 ; Pierre Lévy, M.D. 3,4,5 ; Pierre Chauvin, M.D. 4,5 ; Dorothée Fragny, M.D. 2 ; Isabelle Buchet, M.D. 6 ; Frédéric Chabolle, M.D. 2 1 Assistance Publique-Hôpitaux de Paris, Hôpital Beaujon, Service d ORL et de Chirurgie Cervico-Faciale, Clichy, France; 2 Hôpital Foch, Service d ORL et de Chirurgie Cervico-Faciale, Suresnes, France; 3 Assistance Publique-Hôpitaux de Paris, Hôpital Tenon, Département de Santé Publique, Paris, France; 4 INSERM, U707, Paris, France; 5 Université Paris 6-Pierre et Marie Curie, UMR-S 707, Paris, France; 6 Hôpital Foch, Service de Stomatologie, Suresnes, France Study Objectives: The tongue-retaining device is a customized monobloc oral appliance used in the treatment of obstructive sleep apnea syndrome (OSAS). This study evaluated tongue-retaining device efficacy and its tolerance by patients with OSAS. Methods: The charts of 84 apneic patients were retrospectively analyzed, and patients were contacted by telephone to answer an oral questionnaire. The median follow-up time was 5 years. Results: Based on the apnea-hypopnea index, a complete or partial response was obtained in 71% of the cases. The mean apneahypopnea index decreased significantly from 38 to 14 (p < 0.001) with the tongue-retaining device. The subjective intensity of snoring decreased by 68% (p < 0.0001) and the Epworth Sleepiness Scale score decreased from 9 to 6 (p < 0.05). An age of more than 60 years associated with a mandibular protrusion distance inferior or equal to 7 mm was predictive of a nonresponse (odds ratio [OR]: 7.25; 95% confidence interval [CI]: 1.43-36.7; p < 0.02). The compliance rate, as determined by answers to the questionnaire, was 52% after 5 years of follow-up. Nasal obstruction was a negative predictor of good compliance (OR: 6.94; 95% CI: 0.28-0.79; p < 0.005), whereas patients with Class I occlusion were more compliant than patients with Class II or III occlusions (OR: 3.83; 95% CI: 1.00-2.81; p < 0.05). Conclusions: Tongue-retaining device performance tended to be similar to that of the mandibular advancement device. Thus, teams trained in tongue-retaining device fabrication and fitting may propose it as an alternative to continuous positive airway pressure, taking nasal obstruction into consideration as a contraindication. Keywords: Oral appliance, apnea-hypopnea index, Epworth Sleepiness Scale, side effects, continuous positive airway pressure Citation: Lazard DS; Blumen M; Lévy P; Chauvin P; Fragny D; Buchet I; Chabolle F. The tongue-retaining device: efficacy and side effects in obstructive sleep apnea syndrome. J Clin Sleep Med 2009;5(5):431-438. The treatment of obstructive sleep apnea syndrome (OSAS) is based on either continuous positive airway pressure (CPAP), oral appliances or surgery. 1 CPAP is initially proposed in cases of severe or moderate OSAS with a high degree of somnolence. Oral appliances are an alternative to continuous positive airway pressure (CPAP) or to an operation in case of treatment failure or refusal. They are also proposed in cases of moderate OSAS without somnolence or mild OSAS. 1 Various models of oral appliances have been developed. The most widely used is the mandibular advancement device (MAD). 2 Among other models, the tongue-retaining device (TRD), a monobloc oral appliance that associates moderate mandibular protrusion with the maintenance of the tongue in an anterior position, has been infrequently used. Submitted for publication March, 2009 Submitted in final revised form July, 2009 Accepted for publication July, 2009 Address correspondence to: Dr. Diane Lazard, M.D., Hôpital Beaujon, Service d ORL et de Chirurgie Cervico-Faciale, 100 Boulevard du Général Leclerc, F-92110 Clichy Cedex, France; Tel: 33 1 40 87 55 71; Fax: 33 1 46 25 23 62 ; E-mail: diane.lazard@bjn.aphp.fr Journal of Clinical Sleep Medicine, Vol.5, No. 5, 2009 431 Although the efficacy of TRD in snoring, sleep apnea, and daytime sleepiness has been shown in small populations, 3-8 its tolerance has appeared to be lower 7 than that of MAD 9 in some studies. This might be the reason why it is so seldom prescribed. 2 The aim of this study was therefore to evaluate TRD efficacy and side effects in a population of 84 patients with OSAS. Patients METHODS From June 1997 to July 2006, 107 patients with OSAS were fitted with a TRD in our center. TRD was proposed in 36 cases as an initial treatment (25 cases of moderate OSAS, 11 cases of mild OSAS), and in 71 cases after CPAP intolerance (severe OSAS). Twenty-three patients were not included in this retrospective study because their charts were too incomplete to be studied (initial polysomnography results and detailed clinical evaluation were missing). The charts of the remaining 84 patients were retrospectively analyzed.
DS Lazard, M Blumen, P Lévy et al Pretreatment Evaluation Clinical Evaluation All snoring patients underwent a detailed otorhinolaryngologic examination by 2 senior practitioners highly specialized in OSAS and trained to consult jointly. The clinical examination followed a standardized scheme, which consisted of noting physical characteristics (ie, age, size, and weight) and medical history (in particular, the presence of a nasal obstruction, anatomic or secondary to allergic rhinitis). The Epworth Sleepiness Scale (ESS) was used to evaluate daytime sleepiness (an ESS score 8 was considered pathologic, and patients with an ESS score 11 as highly symptomatic). 10 The sizes of the mobile tongue, tongue base, tonsils, and uvula were graded from 1 to 3 (small, medium, big) or 0 if the patient previously had surgery on one of these structures. The soft palate was classified as thin or plethoric. The relative position of the teeth and the relationship between the upper and lower jaw was evaluated (Class I: normal; Class II: retrognathic; Class III: prognathic). The level of snoring was evaluated by the bedpartner using a visual analog scale from 0 to 10 (0 = no snoring, 10 = snoring loud enough to be heard from another room). Po ly s o m n o g r a p h y Patients underwent an initial polysomnogram (pre-trd) consisting, at a minimum, of recording ventilatory parameters (ie, nasal flow through a nasal cannula, oximetry, and thoracic and abdominal movements) and quantifying sleep time, as evaluated by a questionnaire and by the stability and consistency of recorded signals (Level 3 polysomnography, according to the classification of the American Sleep Disorders Association 11 ) in all patients. In addition, sleep parameters (ie sleep stages, arousal index and microarousal index, and sleep latency) were recorded in some patients (n = 46, Level 2 polysomnography). Because sleep parameters were not available for all patients, only ventilatory parameters and sleep time were taken into account for the purposes of this study. In patients with supine apneas, learning to avoid the supine position 12 was systematically proposed as a first-line treatment in our center. Oral appliances were only indicated in patients who failed this rehabilitation. The subpopulation used for this study is therefore biased, and the results cannot be extrapolated to determine TRD efficacy in patients with supine apneas. The severity of the disease was classified according to the apnea-hypopnea index (AHI) as follows: severe OSAS, AHI of 30 or greater; moderate OSAS, AHI of at least 15 but less than 30; mild OSAS, an AHI of at least 10 but less than 15. 10 The TRD The TRD (Figure 1) was first described in 1982. 3 It consists of a mouthpiece that covers the entire upper and lower dental arches, with a defined mandibular protrusion. It pulls the tongue slightly forward due to the negative pressure created by the displacement of air from the lingual compartment of the device. The TRD is custom made from casts of the tongue and teeth using a soft copolymer (Truplast, Orthoplus, Igny, France). The Figure 1 The tongue-retaining device. Tongue protraction is achieved due to the design of the device, which results in a slight negative pressure in the lingual compartment of the device, following the displacement of air once the tongue is placed in this compartment. initial mandibular protrusion is 50% to 75% of maximal protrusion. 13,14 This protrusion distance is reduced if the patient complains of pain and is increased if snoring remains unchanged after a 3-week trial. Lateral holes facilitate mouth breathing. All patients underwent a systematic dental examination by a stomatologist. Severe periodontal diseases were considered to be criteria for exclusion. For a good fit, we preferred that patients have a minimum of 6 teeth each on the superior and inferior dental arches. Nevertheless, the TRD is the only appliance suitable in case of edentulism and can be used in this case. To summarize, a TRD was proposed according to the AHI recorded during the initial polysomnogram in cases of daytime somnolence or after a CPAP failure. Oral Appliance Evaluation Polysomnography With TRD An outcome polysomnogram (post-trd polysomnography) after a minimum of one month of TRD use (from 1 to 91 months, median = 4) was systematically prescribed. Patients were required to wear the TRD during the test to evaluate its efficacy. The results of the post-trd polysomnogram were classified as follows: when the AHI with TRD was less than 10, the response was considered to be complete; when the AHI decreased by more than 50% and was less than 20 but greater than 10, the response was considered to be partial. Qu e s t i o n n a i r e A telephone questionnaire for the subjective evaluation of the efficacy and side effects of TRD was created for this work, inspired by questions used in previous studies. 9,15 (See Appendix.) From January to March 2007, patients and their bedpartners, when present, were systematically contacted by telephone by Journal of Clinical Sleep Medicine, Vol.5, No. 5, 2009 432
Table 1 Characteristics of the Population with a Tongue-Retaining Device Initial Studied population population n = 107 n = 84 Sex: M/F, no. 85/22 64/20 Age at treatment initiation, y 55 ± 11.0 55 ± 11.0 BMI, kg/m 2 27 ± 3.8 26 ± 3.8 ESS score 9 ± 4.8 9 ± 5 AHI, no./h 36 ± 19.5 37 ± 19.5 Patients with severe OSAS, % 66 76 Protrusion distance, mm 6.7 ± 1.5 7.0 ± 1.5 Post-TRD AHI 120 100 80 60 40 Tongue-Retaining Device in OSAS Data are shown as mean ± SD unless otherwise indicated. a single practitioner who verified that the questions were correctly understood. Because the practitioner was not in charge of these patients, his impartiality regarding their answers was ensured. Subjective Efficacy The efficacy or response obtained with TRD was subjectively evaluated in terms of the sound level of snoring by a visual analog score given to the bedpartner and, in terms of daytime sleepiness, by the ESS. Compliance and Tolerance Patients were classified as TRD users, defined by even sparse use at the time of the telephone call, or nonusers, if the treatment had been completely interrupted by this time. Compliance was also evaluated by the number of nights of TRD use and the duration of use per night (all night, more than half the night, less than half the night). Patients reported the most frequent side effects seen with oral appliances, in addition to reasons for noncompliance. Esthetic problems were included on the list of reasons, considering the singular design of the TRD. Statistical Methods Data are presented as percentages or as means ± standard deviation (SD). Event frequencies were compared using the χ² test or, when numbers were small, the Fisher exact test. The paired t test was used to study objective effectiveness. The Wilcoxon test was used to assess modifications of the visual analog score and the ESS score. We started by using logistic-regression models to select potential covariates, after making adjustments for survey year and some individual characteristics in cycle 4 (age, sex, vital risk, eg, arterial hypertension, heart disease, diabetes, and hypercholesterolemia). We then included all the variables in a multivariate analysis using logistic-regression models to estimate the association between clinical characteristics and efficacy on the one hand and tolerance on the other. All independent variables showing a univariate association with efficacy or tolerance with a p value less than 0.25 were introduced into the regression model and then subjected to backward selection. Decisions concerning potential covariates for the final model (p < 0.05) were based on the Hosmer and Lemeshow approach. Clinical predictors for efficacy and compliance were thus pinpointed. 20 0 Figure 2 Objective assessment of the tongue-retaining device (TRD) by the apnea-hypopnea index (AHI) (n = 55). The diagonal represents an absence of modification of the AHI, points below show a decrease in the AHI, and points above an increase in the AHI with TRD. The dotted line indicates an AHI of 10, ie, a complete response (47% of the cases). The 2 patients in whom the AHI was worse with TRD (empty circles) were users until the post- TRD polysomnogram was carried out. Following the polysomnography results, which indicated an obvious deleterious effect of the device, treatment was stopped. RESULTS Among the 84 patients studied, 55 (65%) underwent the outcome polysomnogram, 63 (75%) answered the telephone questionnaire, and 34 (40%) did both. Population Characteristics In Table 1, the characteristics of the initial population (n = 107) and the selected patients (n = 84) are compared. The 2 populations were not statistically different (χ² test). The mean and median follow-up time was identical for the 84 patients: 5 ± 2.0 years (range: 0.7-8.7). TRD Efficacy 0 20 40 60 80 100 120 Pre-TRD AHI Pr e-trd a n d Po s t-trd Po ly s o m n o g r a p h y Efficacy was objectively evaluated by comparing the AHI before and during TRD use in 55 patients (Figure 2). The group included both users and nonusers because some patients may have interrupted TRD use after the post-trd polysomnogram. A modification of protrusion distance (2-4 adjustments) was carried out in 4 patients. The post-trd polysomnogram taken into consideration took place after these adjustments. All but 4 patients displayed a lower AHI while using the TRD; 2 patients had a higher AHI and 2 did not show any change (AHI of 18 and 20, respectively). A response was obtained in 71% of the cases (39 patients); it was complete in 47% (26 patients) and partial in 24% (13 patients). If we assume that Journal of Clinical Sleep Medicine, Vol.5, No. 5, 2009 433
DS Lazard, M Blumen, P Lévy et al Visual analogic score of snoring 10 8 6 4 2 0 the 29 patients who did not undergo the post-trd polysomnogram were nonresponders and include them in the total number of patients assessed, efficacy response was obtained in 39 of 84 cases (47%), being complete in 26 of 84 cases (31%) and partial in 13 of 84 cases (15.5%). The AHI (n = 55) decreased significantly from 38 ± 22.2 to 14 ± 13.2, corresponding to a mean decrease of 27 ± 21.3 (p < 0.001, paired t test) with the TRD. Other indices decreased as follows: the apnea index (n = 48) from 23 ± 22.4 to 5 ± 9.1 (p < 0.001) and the hypopnea index (n = 48) from 17 ± 14.7 to 8 ± 6.1 (p < 0.001). Sn o r i n g Before TRD While using the TRD Figure 3 Individual visual analog scores indicating snoring before and during tongue-retaining device (TRD) use (n = 39). The figure shows a significant decrease in the intensity of snoring with the TRD (68%, p < 0.0001). Among the 63 patients who answered the questionnaire, 39 had a bedpartner capable of quantifying snoring in the presence or absence of the TRD (Figure 3). All bedpartners estimated that the level of snoring was reduced, except in 1 case, in which it was unchanged. The mean visual analog score without TRD was 8 ± 1.5 out of 10. It decreased to 3 ± 2.0 with TRD use, ie, a decrease of 68% in the intensity of snoring (p < 0.0001, Wilcoxon test). others parameters tested (sex, smoking, nasal obstruction, sizes of the mobile tongue and base of the tongue, size of the tonsils, soft palate thickness, and uvula length) were not significantly correlated with efficacy (data not shown). No predictive value could be discerned for the severity of the OSAS (AHI > 30 or ESS score > 11), a pathologic body mass index (BMI 25 kg/ m 2 ), or an indication for TRD as a first- or second-line treatment after CPAP. The graphic analysis of the 2 significant variables age and protrusion distance allowed us to determine 2 cutoff points: an age of more than 60 years and a protrusion distance of less than 7 mm. Taking these thresholds into consideration, we transformed the 2 variables into a binary composite variable. We found that an age greater than 60 years associated with a protrusion distance inferior or equal to 7 mm was predictive of nonresponse (odds ratio [OR]: 7.25; 95% confidence interval [CI]: 1.43-36.7; p = 0.016). TRD Compliance and Side Effects TRD Use Evaluated by a Telephone Questionnaire There were 33 users (52%) and 30 nonusers (48%) after a mean follow-up period of 5 years. These 2 groups were not statistically different, especially in terms of BMI (27.3 ± 4.2 kg/ m² for users, 27.2 ± 4.1 kg/m² for nonusers) and severity of the disease (AHI = 37.5 ± 18.1 for users, 36.1 ± 18.3 for nonusers). If we included patients who did not answer the questionnaire as nonusers (n = 21), the compliance rate decreased to 39%. Twenty-nine patients (46%) refused an objective assessment of TRD efficacy by means of the post-trd polysomnogram. These included 10 users (30%) and 19 nonusers (63%). Nonusers were significantly more reluctant to undergo the exam than were users (p < 0.01, χ² test). Users wore the TRD more than 4 nights per week in 79% of the cases and more than half the night in 86% of the cases. In nonusers, the trial lasted from less than 1 month (8 patients) to 36 months. The median and mean trial periods were 5 and 11 months (± 13.4), respectively. Among nonusers, 47% went back to CPAP, 41% had untreated OSAS, and 12% tried another type of appliance with satisfaction. Daytime Sleepiness The comparison of the ESS scores before and during TRD use was established for 24 patients. The ESS score decreased with TRD use from 9 ± 5.0 to 6 ± 3.7 (p < 0.05, Wilcoxon test). Five out of the 24 patients (21%) reported an increase in somnolence. Among these 24 patients, only 2 were nonusers, who stopped use just before the telephone inquiry. They wore the device for 18 and 36 months, respectively, and stopped for esthetic reasons in the first case and due to weight loss that led to remission of the OSAS in the other case. Their ESS scores decreased from 20 to 7 and from 13 to 4, respectively. Clinical Predictors of Efficacy After 4 cycles of multiple regression, 2 variables were found to be significant (p < 0.05): age and protrusion distance. The Reasons for Stopping TRD Use The main reasons for discontinuing TRD use reported by nonusers (n = 35 answers in total; 2 causes each were cited in 5 cases) were discomfort or sensation of a foreign body (49%), pain (31%), excessive salivation (8%), excessive mouth dryness (3%), and esthetic reasons (3%). No justification was given in 6% of the cases, and no technical difficulties were reported. Figure 4 shows the evolution of user and nonuser populations with time and the main causes of interruption reported by nonusers (n = 30). The majority of interruptions occurred within the first 6 months (60%). They then decreased and peaked again after 30 months. In the first 6 months, the most common reported reason for stopping TRD use was discomfort. Pain could be divided into 2 categories: pain early in use leading to interruption within the first 6 months, and chronic pain leading to interruption after a period of 30 months. Journal of Clinical Sleep Medicine, Vol.5, No. 5, 2009 434
Tongue-Retaining Device in OSAS Numberof patients 50 45 40 35 30 25 20 15 10 Users Non-users: Other Excessive salivation Pain Discomfort 5 0 6 12 18 24 30 36 Months Figure 4 Evolution of the number of users and nonusers over time, and principal cause of treatment failure (first of 2 possible answers). The term Other groups dryness, esthetic reasons, and unjustified cases (n = 2). No withdrawals were recorded after 36 months. Among the 18 patients who discontinued use within the first 6 months, 8 stopped within the first month. Clinical Predictors of Compliance From a comparison of the clinical examination of users and nonusers, the presence of a nasal obstruction (anatomic or secondary to allergic rhinitis) was a negative predictor of good compliance (OR: 6.94; 95% CI: 0.28-0.79; p = 0.008). A nasal obstruction was present in 69% of the patients who stopped wearing the TRD due to discomfort. In contrast, patients presenting with a Class I occlusion were more compliant than those with a Class II or III occlusion (OR: 3.83; 95% CI: 1.00-2.81; p < 0.05). The other parameters tested (sex, age, smoking, sizes of the mobile tongue and base of the tongue, size of the tonsils, soft palate thickness, uvula length, and protrusion distance) were not found to be significantly correlated with compliance (data not shown). Neither OSAS severity (AHI > 30 or ESS score > 11) nor a pathologic BMI ( 25 kg/m 2 ) was predictive. Side Effects Figure 5 shows the distribution of side effects among users and nonusers. The 2 groups both reported more than 1 side effect. Users complained most about discomfort and excessive salivation. They presented no side effects in 30% of the cases. Compared with users, a higher proportion of nonusers complained about discomfort (p < 0.05, Mann Whitney test). It was considered a side effect and not a reason for discontinuing TRD use. Unfavorable dental modifications (position of the incisors) or parodontopathy while using the TRD were cited by 16% of all treated patients. Dental modifications were considered by patients to be minor. Dental modifications and parodontopathy were associated in 1 user. DISCUSSION This study reports long-term (39 months) TRD efficacy and tolerance in a relatively large population (n = 84). As previous- ly published, adequate medical follow-up of patients suffering from chronic diseases is difficult to achieve 2 : from the initial pool of 107 patients using the TRD, 21% were lost to followup, and 28% did not undergo the post-trd polysomnogram. Because the MAD is the most commonly used appliance in the treatment of OSAS 2, TRD outcomes will be compared with data provided for MAD in the literature. The characteristics and follow-up of our population were similar to that of the populations analyzed for MAD validation in previous studies. 2,15,16 Efficacy Considering the results of the outcome polysomnogram, the TRD was found to be effective in 71% of the cases studied. Similar results have been reported previously for TRD, 3-8 although for shorter trial periods, and for MAD 15,16 over comparable followup times. The fact that the AHI increased in 2 patients underlines the need for objective controls for the evaluation of any kind of OSAS treatment. The effect of TRD on subjective estimations of snoring (a decrease of 68%) was significant and, in particular, better than that reported for MAD (a decrease of 45%-50%). 2,9 The effect on daytime sleepiness was also significant, with an improvement in daytime symptoms comparable to that seen with MAD. 2,9 The assumption that patients who did not undergo the post- TRD polysomnography had discontinued treatment results in a drastic decrease in efficacy (47% vs 71%). Yet, we know from questioning patients that some of them were satisfied with the TRD but did not want to undergo the post-trd polysomnogram for other reasons or that they stopped because of side effects and not due to a lack of response. Compliance Because the principal indication for treatment with TRD in our series was CPAP intolerance, the population studied should Journal of Clinical Sleep Medicine, Vol.5, No. 5, 2009 435
DS Lazard, M Blumen, P Lévy et al 20 18 * Users Numberof patients 16 14 12 10 8 6 Non-users 4 2 0 None Discomfort Excessive salivation Mouth dryness Dental modifications Parondothopathy Figure 5 Side effects reported by users and nonusers. Two or more side effects were reported in 11 patients from each group. These side effects were not listed by nonusers as a reason for stopping use of the tongue-retaining device (TRD). * = p < 0.05 for discomfort in users vs nonusers. be considered to be biased, since patients were selected following the failure of an initial treatment and were less tolerant of the side effects of a new therapy. Nevertheless, the compliance rate after 5 years (52% of users) was quite good considering the rate of interruption within the first month (74%) previously reported for TRD. 7 This compliance rate was similar to the compliance rate for MAD (55% 9-64%). 15 The absence of a difference between users and nonusers in terms of BMI or of disease severity supports the idea that these factors do not influence tolerance, 15 regardless of the appliance being used. In the case of MAD, De Almeida and colleagues 15 estimated that the compliance rate decreases to 30% if nonresponders to questionnaires are considered to be nonusers. For TRD, the compliance rate decreases to 39% when including these patients. However, in our protocol, patients were systematically contacted by telephone, whereas the MAD surveys were carried out with mail-in questionnaires. 9,15 As a result, we may have collected more answers from dissatisfied nonusers who might not have taken the time to fill out a written questionnaire. Daily compliance by TRD users (79%) was close to that of MAD users 15 (92%) when applying the same criterion of use (ie, more often than 4 nights per week). The proportion of users using TRD for more than half the night was 86%, versus 100% for MAD. 15 Side Effects One third of TRD users experienced no side effects. For MAD, the reported rate is 50%. 15 Again, a bias with respect to the questionnaires cannot be excluded. The main reason given by nonusers for discontinuing TRD use was discomfort (48%), which was also the reason cited for MAD (44% 15-52% 9 ). The particular design of the TRD may explain the chronic tongue pain that led to late interruption (> 30 months). Interestingly, even though the tongue remains free within the mouth when using the MAD, tongue discomfort was also cited by patients who discontinued this treatment (up to 24%). 15 As in the case of MAD, discontinuation occurred mainly during the first 6 months. 15 Minor and temporary side effects as well as severe side effects that induced an interruption of treatment were the same for both TRD and MAD. 17 They were more related to oral appliances in general than to the particular design of the oral appliance. The number of unfavorable teeth modifications or parodontopathies with the TRD may have been underestimated, as there was no systematic dental control during our study. Thanks to stone casts, unfavorable changes were recorded in 44% of the cases with MAD. 18 In the future, dental position should be systematically and carefully documented before and during the use of an oral appliance. Clinical Predictors of TRD Efficacy and Tolerance Age greater than 60 years associated with a protrusion distance inferior or equal to 7 mm was found to be a negative clinical predictor of efficacy. With aging, oropharyngeal tissues may become more sensitive to negative pressure during apneas. As a consequence, a larger protrusion threshold (> 7 mm) should be applied in the case of patients older than 60 years. As with other types of appliances, 9,15 age, BMI, sex and daytime sleepiness were not predictive of tolerance. The negative and positive clinical predictors nasal obstruction and Class I occlusion, respectively might help enhance TRD tolerance if looked for during the initial examination. One-piece appliances like the TRD, by totally obstructing the mouth, impose nearly exclusive nasal respiration, which is difficult in patients who have nasal obstruction. The correlation between nasal obstruction and the sensation of discomfort could be related to an unconscious limitation of nasal respiratory airflow. Patients with Class II occlusions would have to undergo greater strain to benefit from (1) mandibular advancement, because it may induce more functional stress on the masticator muscles and temporomandibular joints, 19,20 and (2) lingual protraction, since tongue posture may be more posterior and Journal of Clinical Sleep Medicine, Vol.5, No. 5, 2009 436
Tongue-Retaining Device in OSAS inferior, as described in cases of micrognathia (Treacher Collins and Nager syndromes). 21 To our knowledge, no study of MAD considers predictors of tolerance based on a global clinical examination to determine the best type of appliance to use according to the patient s clinical profile. Cost and Fabrication The cost of the TRD is about 500 Euros, including adjustments, versus 400 to 600 Euros for the MAD in France. Nevertheless, its infrequent prescription by practitioners may be explained by the fact that it is more laborious and time consuming to make. CONCLUSION The TRD was shown to be effective objectively and subjectively, and compliance within the population studied was found to be quite good. Nevertheless, if patients who did not respond to an objective (34.5%) or subjective control (25%) are classified as nonusers, the benefits of this appliance become arguable. 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DS Lazard, M Blumen, P Lévy et al Telephone Questionnaire Appendix 1. Do you still use the TRD? - Yes/No 2. If you still use the TRD, what is your compliance rate? - Do you use it more or less than 4 nights per week? - Do you use it all night, more than half the night, or less than half the night? 3. If you have discontinued use, how long did the trial last (in months)? 4. Please indicate 1 or 2 reasons for stopping TRD use among the following: - Esthetic - Pain. If yes, please indicate the localization: tongue, masticator muscles, temporomandibular joint, teeth, or gums - Excessive salivation - Mouth dryness - Technical difficulties - Discomfort due to the sensation of a foreign body - Other 5. Whatever your user status, did you experience any of the following? - Discomfort - Excessive salivation - Mouth dryness - Subjective feeling of dental modifications - Periodontal diseases 6. Can your bedpartner evaluate the level of snoring with the TRD using a visual analog score from 0 to 10? Scoring was explained. 7. What is your ESS score while using the TRD? The Epworth Sleepiness Scale was read out to patients and the score calculated on the spot. 8. Did you undergo the outcome PSG? - Yes/No. If no, was it because of a refusal to undergo the PSG? Journal of Clinical Sleep Medicine, Vol.5, No. 5, 2009 438