No abstract

Vertical mandibular position is considered to have an effect on the patency of the upper airway, because mouth opening is associated with a backward and downward displacement of the mandible and tongue. This study was conducted to investigate the nature of mandibular displacement at rest and to determine whether or not different respiration modes and body postures influence the mandibular position. The mandibular position was measured by use of a newly developed system with magnets and magnetic sensors placed on the upper and lower first molars, respectively. Vertical mandibular position was significantly affected by the degree of nasal airway obstruction. The proportion of the duration of mouth opening from 0 to 2.5 mm was about 80% in the sitting and lateral recumbent positions and 55% in the supine position. The amount and duration of vertical mandibular displacement were thus significantly increased by experimentally induced nasal respiratory obstruction. Furthermore, it was demonstrated that the amount and duration of mouth opening were significantly greater in the supine posture than in the sitting and lateral recumbent positions. It is thus shown that nasal respiratory disturbance may be a key determinant for mouth opening and breathing and the resultant vertical mandibular displacement.

This study aimed to examine the sleep architecture and craniofacial morphology in a group of children divided by different levels of apnoea-hypopnoea index (AHI), 5, 4.5, 4, 3.5, 3 and 2.5, and to determine an AHI threshold value at which sleep architecture is most affected. 23 children, who were selected from a preliminary questionnaire survey about sleep-related breathing disorders, were evaluated with cephalometric radiographs and overnight polysomnography. The findings indicated that the children with AH1 > or = 2.5 and > or = 3 showed significantly larger numbers of waking (p < 0.005) and desaturation index (p < 0.01) than those with AHI <2.3 and <3, respectively. Significantly (p < 0.05) higher amounts of waking and lower amounts of REM as a percentage of total sleep time (TST) were also found in the children with AH1 > or = 3. In the subgroups with AHI > or = 3.5 and > or = 4, only the percentage of REM was found to be significantly (p < 0.05) lower. No significant differences were found at the AHI threshold of 4.5 and 4. AHI correlated significantly (p < 0.05) with the number of awakenings, amount of waking as a percentage of TST, desaturation index and oxygen saturation nadir. Higher incidence of skeletal Class II pattern was found in children with AHI > or = 2.5 and > or = 3, and Class III in those with AHI <2.3 and <3, respectively. The effects on polysomnographic characteristics demonstrated to be the greatest on children at the AHI threshold of 3. In addition, the evaluation of oxygen saturation can be used to provide some information concerning the severity of sleep-related breathing disorders.

Pacientes com maloclusão assimétrica geralmente apresentam disfunção dos músculos mastigatórios. A correção de mandíbulas assimétricas possibilita a retomada harmoniosa da função estomatognática. Este artigo apresenta o relato de um caso de um paciente adulto, sexo masculino, assimetria mandibular severa, mordida cruzada unilateral e disfunção muscular. Para avaliação da função muscular mastigatória, foram realizados os exames de eletromiografia (EMG) e Dental Prescale System (sistema de medição de pressões) antes e após o tratamento. No estágio inicial as forças oclusais apresentavam-se relativamente baixas (312.6N) durante a mordida máxima dos dentes e a área de contato oclusal era pequena (7.5mm). A resolução do problema foi feita através de tratamento ortodôntico com aparelho fixo e cirurgia ortognática da mandíbula. Após 15 meses de tratamento, foi estabelecida uma oclusão adequada. No estágio final a força oclusal apresentou-se aumentada (579.9 N). A área de contato oclusal durante a mordida máxima dos dentes também obteve um aumento (9.9mm), se comparado ao estágio inicial. Após dois anos de contenção, a oclusão manteve-se estável e sem recorrência de assimetria mandibular, inidicando uma estabilidade oclusal de longo prazo.

The aim of this study was to assess the prevalence of sleep-disordered breathing (SDB) symptoms among primary schoolchildren, and to objectively determine the influence of SDB on the intra-oral environment through the analysis of saliva. A questionnaire survey was conducted among approximately 400 children from a primary school in Hiroshima. Parents were asked to complete the questionnaire and provide their contact information if they allowed the collection of saliva samples from their children. Thirty-eight chil- dren agreed to participate in the saliva study. Habit- ual snoring and cessation of breathing during sleep were found in approximately 8% and 1% of children, respectively. The present results showed significant correlations between snoring and mouth breathing. A significant association between excessive daytime sle- epiness (EDS) and learning problems was found. Fur- thermore, among children between the ages of 7 and 12 years, those with EDS and learning problems tended to be older. SDB symptom scores were statisti- cally significant only in relation to EDS. The present study also demonstrated significantly higher levels of salivary IgA and cortisol in children with sleep-re- lated disorders. The present study determined the pre- valence and characteristics of SDB among Japanese primary schoolchildren and their effects on the oral environment. Approximately 8% of primary school- children with habitual snoring might need to be care- fully monitored for SDB symptoms and immune sta- tus to ensure proper psychological and physical deve- lopment