Treatment of snoring and sleep apnea syndrome with a removable mandibular advancement device in patients without TMD

Results: After treatment, the statistical analysis (t-test, and the “before and after” test) showed a mean reduction of 77.6% (p=0.001) in the apnea-hypopnea index, an increase in lowest oxyhemoglobin saturation (p=0.05), decrease in desaturation (p=0.05), decrease in micro-awakenings or EEG arousals (p=0.05) and highly significant improvement in daytime sleepiness (p=0.005), measured by the Epworth Sleepiness Scale. No TMD appeared during the monitoring period.


IntROduCtIOn
One often hears that when a person is asleep and snoring, it means that they are fast and sound asleep.It couldn't be farther from the truth.A partial obstruction in the upper airway causes snoring while a complete obstruction leads to sleep apnea, which is the total cessation of airflow.These events comprise what is known as Sleep Apnea and Hypopnea Syndrome (OSHAS) and lead to serious consequences such as systemic and pulmonary hypertension, excessive daytime sleepiness, impaired memory, irritability, depression, decreased libido, impotence, burnout, headache and a proneness to workplace and car accidents.Apnea is characterized by an interruption in airflow (breathing) for at least ten seconds.Hypopnea is a 50% reduction in airflow accompanied by a "microawakening" or EEG arousal and/or a drop in blood oxyhemoglobin saturation (SaO2) of about 2% to 4%. 4 It is diagnosed by examining sleep with polysomnography (PSG), which consists of simultaneously recording activities occurring in the organism during a given period and tracking not only the number of apneas and hypopneas during the patient's sleep but also defining OSHAS severity using the apnea-hypopnea index (AHI), which is the sum of apnea and hypopnea events per hour of sleep. 6everal authors have confirmed the validity and effectiveness of oral appliances for OSHAS treatment. 1,2,5,8,9,10,16Appliances that reposition the mandible anteriorly are indicated for primary snoring and mild to moderate OSAHS with an AHI of up to 30 4,9 .
In OSAHS patients this therapy can be effective even in the presence of other diseases such as congestive heart failure and arterial hypertension, 8,19,30 thereby contributing to clinical control.
In treating OSHAS a correct diagnosis is of paramount importance, as well as a multidisciplinary team with training and knowledge of sleep disorders, and a reliable treatment indication for each case.Dentists should be part of this team as they play a key role both in the initial diagnosis, by referring the patient to polysomnography, and in the treatment itself after the examination.
The purpose of this study was to develop an alternative intraoral appliance model for treating OSHAS, evaluate its effectiveness and magnitude of changes in AHI, and observe the side effects and development of potential TMD (temporomandibular dysfunction) signs and symptoms in the follow-up phase.

MateRIal and MetHOdS
The study evaluated 15 patients among those who presented voluntarily at the Clinic of Sleep Disorders located in Bauru, Brazil, reporting excessive daytime sleepiness and/or snoring.Patients had a mean age of 49.9 years.
Initially, patients answered a questionnaire, the Epworth Sleepiness Scale (ESS), designed to measure their daytime sleepiness in specific situations, 15 including patients with ESS scores greater than five.Examination to check for the presence of Temporomandibular Disorders (TMD) began with the patient's clinical history using the Anamnesis Index (AI) questionnaire. 7,11,18The results were compared with the AI table, which classifies patients' TMD, thus: 0-15, no TMD, 20-40, mild TMD, 45-65, moderate TMD, 70-100, severe TMD.Thereafter, a physical and clinical examination was performed by digital palpation of the right and left TMJs and muscles (superficial and deep masseter, medial pterygoid and temporal).Patient response to TMJ palpation was graded as suggested by Pertes and Gross 21 and as performed by Miranda. 18Therefore, assessment of the development of TMD signs and symptoms was performed by comparing AI before and after treatment, and also by physical examination, i.e., palpation of masticatory muscles and TMJ.
Exclusion criteria were as follows: AI higher than 15 (since subjects with AI between zero and 15 are considered without TMD, and above 15, with TMD) or presence of TMD signs and symptoms, moderate or severe periodontal disease, lower than 6 mm maximum mandibular protrusion and less than 35 mm mouth opening.
All patients underwent polysomnography (PSG) in the Clinic of Sleep Disorders before and after wearing the appliance.The average time interval between PSGs was five months.
During fabrication, the adjustable mandibular advancement splints were waxed, made with an opening from canine to canine (1.5 mm on average) and processed.Stainless steel wires were also used for mechanical support to prevent the acrylic from fracturing.A 13 mm palate expander screw was Treatment of snoring and sleep apnea syndrome with a removable mandibular advancement device in patients without TMD original article employed to join the maxillary to the mandibular portion of the splint (Fig 1).
At each visit after splint insertion it was advanced by 0.25 mm until the mandibular advancements reached 1 mm within a two-week period.Patients were monitored on a weekly basis and, after reporting an improvement in snoring and sleepiness, were referred for a second PSG.After approximately six months wearing the splint, the patients were examined again to assess TMD development.
The tests used for statistical analysis of the results included Student's t-distribution test for small samples, with degree of freedom (df ) lower than 120 and the "before and after" test which, in simple comparative experiments with samples that have the same origin, ensures greater accuracy than t-test.Both tests were applied to ensure outcome reliability.

ReSultS
Anthropometric data of the subjects who participated in the research are presented in Table 1.
The data were statistically evaluated by Student's t-test and confirmed by the "before and after" test.Assessment results of daytime sleepiness before and after splint use are depicted in Table 2.
All patients exhibited decreased ESS values, noting that the treatment reduced excessive daytime sleepiness in a highly significant manner in 87% of the patients (p=0.005).
It is noteworthy that AI variation was not sufficient to affect the TMD classification of any patient, i.e., it did not increase over 15.On physical examination by muscle palpation 14 patients showed no significant differences after treatment compared to muscle palpation values found prior to treatment.
During mandibular advancement therapy patients 6 and 15 (13.3%) developed morning muscle pain. 10reatment included the prescription of oral medication (Celecoxib 200 mg) once a day for three days.The mandibular advancement was halted for a week and then restarted at 0.25 mm per week. 2 The two patients were left with the splint positioned 1 mm below the 75% of maximum protrusion mark.These two patients never again exhibited TMD signs and symptoms.
Table 4 presents the oxyhemoglobin saturation index, number of arousals and number of apneas and hypopneas occurring per hour during the first and second PSG.
On the one-tailed Student's table for p=0.05 and df=14, tc = 1.761 with 95% confidence for the situation "with splint", the amount of oxyhemoglobin desaturation events decreased significantly.
For the one-tailed test tc=1.761(hence to>tc), the number of arousals "after" is significantly lower than "before." Snoring, as evaluated by PSG, improved in all patients to acceptable levels and was suppressed or not observed in patients 4 and 15 (moderate frequency level) and in patients 5 and 8 (high frequency).
AHI before treatment had a baseline mean of 18.3 (SD=11.8).After treatment, the AHI displayed a mean of 4.1 (SD=3.8,p=0.001).Thus, the outcome for "after" is significantly less than for "before", i.e., there was a highly significant reduction in AHI.

dISCuSSIOn
The aim of this study was to evaluate the effectiveness of an adjustable intraoral mandibular advancement splint in the treatment of OSAHS. 5,9,19urrently, it is recommended that to be considered successful OSHAS treatment using oral splints must comply with the following polysomnographic parameters: A reduction in AHI of at least 50% or a reduction in AHI values below ten. 16 highly significant reduction in AHI found in 15 patients, i.e., 77.6% mean reduction, demonstrates that the splints can be indicated for treating snoring, increased upper airway resistance syndrome and OSAHS cases of mild to moderate severity, although some patients with severe OSAHS can also benefit from the therapy, such as patient 12 in this research.When patient 12 was excluded so that the data analysis could be restricted to patients with AHI<30 only, a highly significant improvement in AHI was still found, i.e., a mean 75.9% (p=0.001).Nine (81.8%) out of 11 patients with AHI>10 showed a reduction in AHI to values below ten.It was observed that mandibular repositioning caused a reduction in AHI.Upper airway narrowing due to anatomical factors such as a posterior positioning of the mandible is a risk factor for sleep apnea.In advancing the mandible, the splints widen and stretch the muscles, which concurrently produce an increase in electromyographic activity, widening the airway and improving airflow.1,2,14,17,19,26 Thirteen patients (86.7%) exhibited some degree of tooth sensitivity, especially on awakening in the morning.With splint use, five patients (33%) complained of excessive salivation at night and one patient (6.6%) complained of dry mouth at night.In this study, specifically in regard to the development of joint or muscle pain, therapy with splints did not produce definitive or reversible TMD signs or symptoms.Yoshida 29 found these effects in 8.5% of cases and described them as transient.None of the participants was diagnosed with TMD prior to treatment, and after treatment completion (12-month followup, on average), no signs or symptoms of TMD-related muscle or joint dysfunction were identified.
It is noteworthy that harmful side effects such as tooth sensitivity (86.7%), dry mouth or excessive salivation (40%) occurred after splint placement but on examination were considered minor or mild. 12,19,23,24,25uthors have indicated that the advancement should be between 50% and 75% of maximum mandibular protrusion 2 since such repositioning would be within the measurements of a physiological mandibular protrusion. 22Six patients had muscle pain and two patients (P6 and P15) presented with moderate pain, which prevented further advancement to 75% maximum protrusion, although the pain was controlled with non-steroidal anti-inflammatory medication.No other changes occurred in AI, indicating no development of TMD signs and symptoms.
The splints were inserted at 60% maximum protrusion and advanced in increments of 0.5 mm to 1 mm within two weeks, unlike other studies, which made weekly advancements of 0.25 mm. 20n this study, the mean mandibular advancement was 9.17 mm, ranging from 7 to 12 mm, therefore within what is considered a physiological protrusion length.These results are similar to several studies that proved the effectiveness of splints in mild and moderate OSAHS. 5,9,30dvancement was discontinued based on the following criteria: A position that coincided with 75% maximum protrusion and improvement in subjective criteria reported by patients.Clinically, however, defining such criteria can prove elusive.Some authors have therefore suggested an association with objective parameters at the end of mandibular advancement therapy, such as nocturnal pulse oximetry performed at home. 10,28eports of improvement in snoring and daytime sleepiness led four patients (26.7%) to an early referral for a second PSG, but the results showed no change in AHI.This situation showed that the reports of patients and/or of their room-mates are indeed subjective and not a substitute for polysomnography as a therapeutic assessment tool. 9,16Further advancements were made in these patients and another PSG was performed for each one, except for patient P11, who refused to repeat it and was the only patient who showed no reduction in AHI above 50% (42.4% reduction).
Therapy with the splint caused a direct effect on sleep fragmentation as there was an increase in the lowest oxyhemoglobin saturation index (p=0.05)and a significant decrease in total desaturation and number of arousals (p=0.05).Clinically, improvement in polysomnographic parameters was found to be related to a significant decrease (p=0.05) in ESS. 8,19provement in snoring levels was observed in all cases and the subjective assessment of spouse confirmed this result.Spouse satisfaction is extremely important since for him or her snoring can cause another sleep disorder, i.e., insomnia. 4ong-term studies are warranted to compare the designs and materials used in the splints and to verify the occurrence of any potential desirable or undesirable effects. 3However, even if significant side effects do occur, a thorough evaluation -pinpointing favorable and unfavorable biological factors -should be conducted and discussed to enable treatment decisions that benefit the patient in the best possible way while gaining control over the important and severe complications of OSAHS.Although treatment using a splint is regarded as a non-invasive therapy, side effects are likely to occur during treatment.Occlusal changes may occur with long-term use, so patients should be strictly controlled. 27hen patients feel the benefits of therapy using the splint and realize that they are waking up feeling rested, they start wearing it on a daily and continuous basis. 13lthough this splint was fabricated with materials normally used in dental practice (such as acrylic resin), in light of the limitations of this study and the success criteria adopted for the AHI reduction (above 50%), splint effectiveness was successfully evaluated and the results consistent with those found in the literature.

COnCluSIOnS
Results indicated that the splint developed for this study proved to be a viable alternative for treatment of mild to moderate OSAHS.Therapy using splints did not developed definitive TMD signs and symptoms during the evaluation period.There was a highly significant reduction in AHI above 50% in 93.3% of patients (mean 77.6%) an increase in lower oxygen saturation, reduction in desaturation, decreased number of micro-awakenings or EEG arousals, and subjective improvement in snoring and excessive daytime sleepiness.Undesirable effects were considered minimal and controllable, and no definitive TMD signs and symptoms were found to occur.

Figure 1 -
Figure 1 -Adjustable mandibular advancement splints used in patients with OSAHS.

Table 1 -
Anthropometric data of research participants.

Table 2 -
Results of the Epworth Sleepiness Scale (ESS) before and after splint use.

Table 3 -
Anamnesis Index (AI) results before and after splint use.

Table 4 -
Oxyhemoglobin saturation index (%) and number of arousals and obstructive events per hour (AHI).