Introduction:
Mandibular advancement devices (MADs) are an alternative to continuous positive airway pressure for patients with mild to moderate SAHS. However, CPAP has drawbacks which causes rejection in some patients.

Material and methods:
Retrospective descriptive study of patients treated with MAD in our center. Variables: age, sex, BMI, AHI, ODI, mean SpO2, minimum SpO2 and TC90% at the beginning and after treatment with MAD when the maximum clinical effect valued by the patient and the Maxillofacial Surgeon has been reached have been collected. We have compared paired samples with non-parametric methods due to the low number of patients and non-normal distribution of the respiratory variables.

Results:
67 patients. 39 had a sleep study before and after DAM placement. 51.3% women, mean age 50.8 (10.5) years and BMI 27.6(3.5). We found the following results of the respiratory variables: table 1.

Statistically significant changes are observed in the AHI and ODI. But when analyzing the diferences individually, there is a great variability with differences in the average AHI of 12.5(16.7) and differences in the average ODI of 10.9(18.3), which in practice means that 9 patients show a worse AHI and 10 patients a worse ODI with the MAD. After a follow-up period, 11(28.2%) patients have dropped out the MAD, 9 for lack of improvement

Conclusions:
- We found a significant reduction in AHI, ODI and 90% TC and not in average or minimum SPO2.
- Due to the great variability detected between patients, it seems advisable to try to objectify the real response of each specific patient by means of polygraphy/polysomnography.
- The high number of withdrawals from treatment with DAM in our series is striking.