obstructive sleep apnea syndrome ( osas ) is a common disease that involves at least 4% of males and 2% of the female adult population . the epworth sleepiness scale describes the patient`s own , subjective experiences and is based on a questionnaire and patient interview . polysomnography , which is carried out using highly specialized equipment , measures several vital functions , the most important of them being the apnea - hypopnea index ( ahi ) . in this index a pause of non - breathing greater than 10 seconds or a reduction of breath airflow which is greater than 50% scores one point . points are counted on an hourly basis as described in the american academy of sleep medicine classification . the grade or severity of osas according to ahi has been categorized as follows : ahi less than 5 - no disease ; ahi 5 to 15 - mild disease ; ahi 15 to 30 - moderate disease ; ahi greater than 30 - severe disease . conservative treatment includes weight loss and the regular use of continuous positive airway pressure ( c - pap ) equipment and a variety of devices that attempt to keep tissues in the anterior part of the upper airway forward . c - pap treatment has been regarded as the  gold standard  in the treatment of osas . it has been recommended as an initial treatment in the presence of severe disease . many patients , however , complain that c - pap is cumbersome and difficult to tolerate . this is especially so among elderly patients in whom c - pap is regarded as the treatment of choice . bimaxillary advancement surgery ( bmas ) has been shown in a number of studies to be an effective surgical modality to treat osas and bma`s effect was comparable to c - pap treatment . in our own previously published study we showed that bmas of the jaws improved osas airway parameters   and relieved the symptoms of osas . a conservative non - surgical technique involving a tooth - borne appliance to advance the mandible without surgery also known as the mad has already been introduced in the late 1990`s . mad has been shown , to provide satisfactory treatment of mild to moderate osas . however , there is a limitation in using mad in completely edentulous patients or those patients with pre - existing temporomandibular joint diseases . mad has also been recommended in the treatment of severe osas [ 17 - 19 ] , especially if the patient is unable to tolerate a c - pap device [ 20 - 22 ] . intolerance towards c - pap equipment occurs in many cases , particularly in obese patients . the weight of osas patients is problematic as overweight patients have more severe disease and respond poorly to all forms of treatment . the purpose of this study was to investigate the effect of a mandibular advancement device on different grades of obstructive sleep apnea using a relatively simple test for the apnea - hypopnea index ( which represents the number of apneas or breathless episodes which occur per hour while a subject is sleeping ) to determine if a mandibular device will be effective . in addition , the study aimed to observe whether the patient s body mass index , age or gender had an influence on the effect of treatment with a mandibular advancement device . the study material consisted of 68 consecutive osas patients ( 19 females , 49 males ) for whom a mad was prepared . the retrospective study was carried out with the permission of the the ethical committee of the oulu university hospital using patient registry data . the data were analysed without personal identifying details and the data were treated with the principles of the helsinki declaration . osas patients were referred to the oral and maxillofacial surgery department ( omfd ) of oulu university hospital for consultation and treatment mainly by the pulmonary division of the department of internal medicine , oulu university hospital ( pddim ) or the otolaryngologic department ( ent ) of the same hospital . the initial examination of the patients and determination of the osas diagnosis was performed by the pddim as well as the decision to start the treatment by c - pap or refer the patients further either to ent clinic or directly to omfd . c - pap treatment was started for all severe cases of osas according to the pddim protocol . mild and moderate cases are mostly sent from pddim to omfd for evaluation and the possibility of providing either conservative mad management or oral and maxillofacial surgical treatment . patients , who could not tolerate c - pap , were also referred to omfd . the decision to use a mandibular advancement plate is made by the omfd in every case . some of the revised patients were also evaluated for surgical - orthodontic treatment with bimaxillary surgery . a total of 68 consecutively referred osas patient for whom the mad treatment was selected , were therefore included in this study . the initiation of the treatment was from july 2005 to december 2013 . in all cases patients were also judged as not suitable for mad treatment , if they suffered from pre - existing active temporomandibular joint dysfunction or if their dental status or periodontal health precluded them from wearing an oral appliance . patients  age , bmi , general health and such did not influence the selection . complaints such as minor occlusal changes or temporomandibular joint problems during the treatment did not affect the study course in any case ( figure 1 ) . flow diagram illustrating cases included , excluded and assessed with polysomnography in study . in this study the mad patients were divided into three groups according to their pre - treatment or baseline polysomnography results :   the gender , ahi , ahi in the supine position , mean ages and bmi of these patients are presented in table 1 . demographic and clinical characteristics of 68 patients with various severities of obstructive sleep apnea 
  n = total number of patients ; ahi = apnea - hypopnea index ; sd = standard deviation . in this mad  was a custom - made acrylic monoblock splint which was specifically manufactured for each patient . each device was fabricated by a dental technician at the same dental laboratory ( hammas - sampo , oulu , finland ) . mad were made using individually made plaster casts of the teeth , and a bite registration taken using the george gauge instrument ( dr . peter t. george , honolulu , hawaii , usa ) by a hospital dentist . the mad was designed so that the mandible was in an advanced position of 50% of its maximum protrusive capacity . the device provided occlusal coverage of all the teeth . a vertical distance between the maxillary and mandibular portions of the device was designed to allow for a breathing opening in the anterior region of the device ( figures 2 and figure 3 ) . a mandibular advancement device designed with an opening in the anterior region of the device for breathing . a mandibular advancement device in position in the mouth . a standardized polysomnography was performed to determine the pre - treatment diagnosis and for the intra - treatment control after the mad treatment was initiated . the mean between the onset of mad treatment and the first control measurement was 0.72 years with a standard deviation of 0.61 and a range of 0.4 to 2.9 years . the influence of this variable period was also studied by the authors . the testing device used for this purpose was a portable embletta goldtm ( resmed , broomfield , colorado , usa ) polysomnography system . the following criteria were observed during polysomnography : flow pressure ( nasal cannula ) , oral pressure ( thermistor ) , snore ( nasal pressure ) , abdominal movement , thoraracic movement , spo2 average ( oximeter ) , pulse rate ( oximeter ) , body position , activity , event marker , leg movements . the registered data were analyzed using remlogictm psg software ( natus medical incorporated , san carlos , california , usa ) by the same experienced clinical neurophysiologist for each case . descriptive statistics were prepared with means , standard deviations and ranges ( m [ sd ] , [ r ] ) . chicago , il , usa ) . the significance level was set at p  0.05 . the patient s pre - treatment mean ahi in the classification groups of mild , moderate and severe , was registered and counted . the changes in ahi ( both mean and supine ) were followed in the different severity groups both in ordinal numbers and in percentages according to pre - treatment classification groups ( table 2 ) . those , whose ahi fell below 5 with mad treatment were considered to be cured ( tables 3 and 4 ) . since some studies consider responders to experience an improvement of ahi of 50% or more to be a success , these results are also tabulated to reflect to this concept for an additional comparison ( table 5 ) . post - treatment apnea - hypopnea index ( ahi ) results of 68 patients with various severities of obstructive sleep apnea treated with a mandibular advancement device 
  n = 68 represents 68 patients in this study having ahi > 5 . n = 59 represents the 59 patients that were capable of tolerating ahi measurements in the supine position . improvement in post - treatment obstructive sleep apnea severity classification 
  n = total number of patients with either mild , moderate or severe grades of obstructive sleep apnea . patients with post - treatment apnea - hypopnea index ( ahi ) scores of less than 5 were considered to be  cured  . apnea - hypopnea index ( ahi ) in supine position in 59 of the 68 patients who were able to assume a supine position during polysomnography for ahi determination 
  n = total number of patients with either mild , moderate or severe grades of obstructive sleep apnea . patients with improvement of their apnea - hypopnea index ( ahi ) scores by at least 50% used as the criteria to assess responder patients 
  the influence of the patient s age , sex , bmi and the time interval between the onset of the mad treatment and the control measurement to determine the decrease of ahi were analyzed statistically in table 6 where a logistic regression model was used to estimate the probability of treatment success . those patients whose ahi fell to a level below 5 were considered as cured of their osas condition . the patients with mild pre - trial sleep apnea symptoms were predicted to have odds of healing as 14.92 ( p = 0.0004 ) times the odds of healing in the group of patients with severe pre - trial symptoms . the odds for healing in patients with moderate pre - trial symptoms were predicted to be 5.42 ( p = 0.077 ) times the odds of healing for the severe group . an increase in the bmi index of one unit was expected to cause a statistically significant decrease in the odds for healing ( or = 0.83 , p = 0.027 ) . no statistically significant change in table 6 was noted when the patient s age ( p = 0.145 ) or time between the start of mad therapy and the control intra - treatment measurements was added to the model ( p = 0.211 ) or when the bmi index in the model was replaced with predictors such as age or time between the measurements . logistic regression model 
  a logistic regression model used to estimate the probability of treatment success . those subjects whose apnea - hypopnea index fell below 5 were considered to as cured . body mass index ( bmi ) in this model the differences between groups mild , moderate and severe was slightly greater and the effect of bmi was not significant ( p = 0.8 ) . the mandibular protrusion was set at 50% of the maximal protrusion because this amount of advancement has been shown to be effective by other authors . while more pronounced mandibular advancement has been shown to be more effective in reducing ahi , the untoward effects are increased with excessive protrusion and compliance is reduced . this 50% of maximal mandibular protrusion is therefore accepted as a good compromise . according to the results of this study an average fall of 65% in ahi the results of mad treatment in the mild group were positive with 25 out of 31 patients achieving an ahi reduction to the cured levels . mad treatment also improved the condition of 5 of the other 6 remaining mild ahi patients , although they were not cured . for an unknown reason , one female patient s ahi classification deteriorated as it rose up to  moderate  disease . in the case of moderate osas 15 out of 23 patients were cured ( with an odds ratio of 5.42 ) , 7 others experienced an ahi reduction which allowed them to be reclassified to the mild group . . these results of this study are in agreement with many previous studies [ 3,4,14 - 19,24,25 ] . in fact mad treatment cured the majority of the patients and improved the ahi of many of those who were not cured . in this material 46 patients of the mild and moderate groups ( totalling 58 patients ) became cured and the remaining 12 patient`s conditions were significantly improved . the mean residual ahi in these groups was below 5 ( being 3.1 and 4.5 ) . the odds ratio showed that a patient with mild osas has 15 times and one with moderate has a 5.4 times better chance of being cured with a mad than a patient with severe disease . the results also showed that ahi can be used to determine the effectiveness of a mandibular positioning device in mild to moderate ahi . the mean numerical decrease of ahi in this severe group was a mean of 20.8 , with remaining residual ahi of 26.7 . two patients out of 14 patients became cured , 3 patients improved from severe to mild and 4 patients improved from severe to the moderate group , while 5 patients remained in severe group . the mean percentage decrease in ahi was less than in the groups with initially moderate or mild osas . this could be , at least partly , explained by a higher mean bmi in this severe patient group . the results show that mad had a less positive effect on patients with bmi > 30 . on the other hand some of the patients in the severe group had a considerable decrease of ahi . the results of this study show the same phenomenon , that people with high supine ahi and lower mean ahi get an especially good response from mad . when supine ahi values are considered and the patients are divided in groups ( table 4 ) then there were 13 patients in the mild group , 14 in the moderate group and 32 in the severe group . from the 13 mild supine patients 8 were cured and 5 remained at their initial ahi severity grouping . patients with higher supine position classification for example moderate and severe showed a favourable trend ( table 4 ) . the patients in severe group ( 46.4 years ) were younger than the patients in the mild ( 53 years ) and moderate ( 55.3 years ) groups . it might be worthwhile to note that the patients with severe disease were heavier and younger than the average of the entire study group . the data of this study indicates that age did not have a significant influence on the outcome of mad treatment . in patients with mild or moderate osas the bmi was near normal ( 26.9 and 26.8 respectively ) while the patients with severe osas were considerably heavier ( mean bmi 30.9 ) . also the decrease in ahi with mad treatment was worse in patients with high bmi values . the bmi had a significant influence on the effect of mad ( table 3 ) . this does not mean , however , that the treatment of obese patients with mad would be unjustified . patients with severe osas were all men and their bmi was significantly higher than the rest of the study material . in this study the mean decrease in ahi was 65.2 with 76.2 in females and 52.2 in males . while the females had a better response , it was not statistically significant . responder patients versus cured patients patients with osas were considered cured if their ahi scores dropped to less than 5   and these cases are presented in tables 3 and 4 . responders were defined as patients with a reduction in ahi following mad treatment of greater than or equal to 50% compared to pre - treatment ahi scores . non - responders were defined as patients with a reduction in ahi of less than 50% . the results in table 5 show that an improvement of more than 50% can be expected in the majority of osas cases treated with mad , particularly in the mild and moderate groups where there is an improvement of 75% . the same pattern follows in the supine position where there is a 74% improvement in the mild and moderate groups . the results of treating severe osas with mad appear less predictable . in some severe osas cases treatment with a mandibular advancement device is very effective in treating mild and moderate obstructive sleep apnea and this is supported by numerous previous studies . one unique feature of this study is that with the simple test of the apnea - hypopnea index the authors were able to determine if the use of a mandibular repositioning device will be effective , thus saving time and costs associated with further more complicated diagnostic tests . treating severe obstructive sleep apnea with therapy using a mandibular advancement device is more controversial . the expectation for full recovery is not very high with severe obstructive sleep apnea patients , but considerable improvement in the apnea - hypopnea index levels may occur . a control polysomnography to assess treatment outcome is necessary especially in severe obstructive sleep apnea cases . further treatment is required if therapy with a mandibular advancement device does not produce satisfactory outcomes . if continuous - positive airway pressure , which is another alternative , is not tolerated by the patient , then very limited conservative treatment modalities remain . it is equally worthwhile to treat both females and males with a mandibular advancement device disregarding the age . the results of the study also show that treatment with a mandibular advancement device is less effective in patients with higher body mass index values ( bmi > 30 ) . this does not mean that treating overweight patients with a mandibular advancement device would be contraindicated .
abstractobjectivesthe purpose of this study was to investigate the effect of a mandibular advancement device on different grades of obstructive sleep apnea using a relatively simple test for the apnea - hypopnea index to determine if a mandibular device will be effective.material and methodsa total of 68 patients with obstructive sleep apnea syndrome ( osas ) including , 31 with mild , 23 with moderate and 14 with severe osas were treated with a mandibular advancement device ( mad ) and monitored with polysomnography.results25 of the 31 mild , 15 of the 23 moderate and 2 of the 14 severe osas patients were cured of their osas if a post treatment apnea - hypopnea index of less than 5 is regarded as cured . 
 the odds ratios for success with mad therapy are 3 for women over men , 14.9 for mild obstructive sleep apnea , 5.42 for moderate obstructive sleep apnea if severe obstructive sleep apnea is assigned an odds ratio of 1.conclusionsthe use of the apnea - hypopnea index alone is useful in mild and moderate disease to predict the effectiveness of mandibular advancement device . 
 treatment with a mandibular advancement device is very effective in treating mild and moderate obstructive sleep apnea . 
 conservative treatment with a mandibular advancement device can be successful in less severe grades of sleep apnea and may be an alternative for non - surgical patients with severe obstructive sleep apnea intolerant of continuous positive airway pressure management .