The efficiency of the oral appliance therapy in patients with obstructive sleep apnea/hipopnea syndrome (OSAS) is a subject under debate in the literature. Orofacial anatomic characteristics affect the respiratory obstruction in distinct ways. The aim of this study was to investigate the influence of the orofacial categories on the respiratory obstruction. The effect of nasal obstruction was also analyzed.
The studied patients were divided in six groups according to their Angle’s classification in I, II, III classes (normal, mandibular retrognathism, mandibular prognathism, respectively), and the presence of nasal obstruction. All of these patients have no history of smoke or preexisting respiratory disease. Their anthropometric characteristics are described in Table 1
Anthropometric characteristics of the subjectsAGE (years)WEIGHT (kg)HEIGHT (cm)Class I Normal (n=20)38.0±13.061.4±10.9165.6±9.0Class I Obstruction (n=28)40.7±14.364.1±.16.1165.7±9.0Class II Normal (n=6)39.5±13.359.3±7.3163.0±10.2Class II Obstruction (n=10)37.9±10.566.2±12.8165.2±10.8Class III Normal (n=5)36.2±20.268.8±11.8167.4±9.7Class III Obstruction (n=8)31.9±16.573.5±12.2169.4±9.0.The airway obstruction was evaluated by the respiratory impedance, measured by the forced oscillation technique using analysis from the nose (ZN) and from the mouth (ZM) at a frequency of 5 Hz One-way analysis of variance (ANOVA) was used to assess the differences among the classes and statistical difference were considered with a p-value <0.05.
The results are presented in Table 2
Airway obstruction in different orofacial categoriesZN (cm H2O/L/s)ZM (cm H2O/L/s)Class I Normal4.3±1.32.8±0.8Class I Obstruction6.0±3.43.8±1.9Class II Normal4.7±1.03.4±0.8Class II Obstruction7.6±3.14.4±2.2Class III Normal6.3±0.73.9±0.4Class III Obstruction8.4±3.04.6±0.9. Significant increases in ZN (p<0.01) and ZM (p<0.05) were observed as a result of the modifications in Angle’s class in normal subjects. Although small increases in ZN and ZM were observed in patients with nasal obstruction, these were not significant (p>0.05).CONCLUSIONS: The results demonstrated that the mandibular skeletal variation has positive influence in the airway obstruction, increasing the impedance with Angle’s craniofacial classification. This effect is reduced in the presence of nasal obstruction.
In order to optimize the use of intra-oral appliances therapy in patients with sleep apnea/hypopnea syndrome, it is important to underwent a previous analysis, and eventual treatment, of craniofacial structure differences and nasal obstruction.
F.M. Sekito, CNPq, Grant monies.