Intra-oral compartment pressures: a biofunctional model and experimental measurements under different conditions of posture

Oral posture is considered to have a major influence on the development and reoccurrence of malocclusion. A biofunctional model was tested with the null hypotheses that (1) there are no significant differences between pressures during different oral functions and (2) between pressure measurements in different oral compartments in order to substantiate various postural conditions at rest by intra-oral pressure dynamics. Atmospheric pressure monitoring was simultaneously carried out with a digital manometer in the vestibular inter-occlusal space (IOS) and at the palatal vault (sub-palatal space, SPS). Twenty subjects with normal occlusion were evaluated during the open-mouth condition (OC), gently closed lips (semi-open compartment condition, SC), with closed compartments after the generation of a negative pressure (CCN) and swallowing (SW). Pressure curve characteristics were compared between the different measurement phases (OC, SC, CCN, SW) as well as between the two compartments (IOS, SPS) using analysis of variance and Wilcoxon matched-pairs tests adopting a significance level of α = 0.05. Both null hypotheses were rejected. Average pressures (IOS, SPS) in the experimental phases were 0.0, −0.08 (OC); −0.16, −1.0 (SC); −48.79, −81.86 (CCN); and −29.25, −62.51 (SW) mbar. CCN plateau and peak characteristics significantly differed between the two compartments SPS and IOS. These results indicate the formation of two different intra-oral functional anatomical compartments which provide a deeper understanding of orofacial biofunctions and explain previous observations of negative intra-oral pressures at rest

A influência do protocolo de extração de dois pré-molares superiores na estabilidade oclusal do tratamento da Classe II Influence of the extraction protocol of two maxillary premolars on the occlusal stability of Class II treatment

OBJETIVO: com o propósito de avaliar a influência da extração de dois pré-molares superiores na estabilidade oclusal do tratamento da má oclusão de Classe II completa, foi realizada uma comparação com o protocolo de tratamento sem extrações. MÉTODOS: selecionou-se, a partir das documentações do arquivo da Disciplina de Ortodontia da Faculdade de Odontologia de Bauru, uma amostra composta pelas documentações de 59 pacientes com má oclusão de Classe II completa. Em seguida, dividiu-se essa amostra em dois grupos, apresentando as seguintes características: Grupo 1, constituído por 29 pacientes, tratados sem extrações; e Grupo 2, composto por 30 pacientes, tratados com extrações de dois pré-molares superiores. Os modelos ao início do tratamento, ao final do tratamento e em um período mínimo de 2,4 anos após o tratamento foram medidos e avaliados por meio dos índices oclusais IPT e PAR. As condições oclusais ao final do tratamento e no estágio pós-tratamento, o percentual de recidiva e as alterações oclusais pós-tratamento foram comparados por meio do teste t. RESULTADOS: os resultados demonstraram que os protocolos de tratamento sem extração e com extrações de dois pré-molares superiores não apresentaram, em nenhuma das variáveis avaliadas, diferenças estatisticamente significativas em relação à estabilidade oclusal do tratamento da má oclusão de Classe II completa. CONCLUSÃO: a extração de dois pré-molares superiores no tratamento da má oclusão de Classe II completa não influenciou a estabilidade dos resultados oclusais alcançados ao final da correção ortodôntica. Portanto, terminar o tratamento com uma relação molar em Classe II ou em Classe I proporciona estabilidade semelhante.<br>OBJECTIVE: With the purpose of evaluating the influence of two upper premolar extraction on the occlusal stability of full cusp Class II malocclusion treatment, a comparison was performed with a non-extraction treatment protocol. METHODS: To this end, a sample consisting of 59 patients with complete Class II malocclusion was selected from the files of the Department of Orthodontics of the Dental School of Bauru. This sample was split into two groups according to the following characteristics: Group 1 included 29 patients treated without extractions and Group 2 included 30 patients treated with the extraction of two upper premolars. Using the TPI and PAR occlusal indices the subjects' study models were evaluated at the beginning and end of treatment, and at a minimum of 2.4 years after treatment. The occlusal conditions at the end of treatment and in the post-treatment period, the percentage of relapse and post-treatment occlusal changes were compared using Student's t-test. RESULTS: The results showed no statistically significant differences between the nonextraction and the extraction of two maxillary premolars treatment protocols in terms of the occlusal stability of complete Class II malocclusion treatment in any of the evaluated variables. CONCLUSIONS: The extraction of two upper premolars in the treatment of Class II malocclusion did not influence the stability of the occlusal results achieved at the end of the orthodontic treatment. Therefore, a similar stability is achieved by finishing a treatment with either a Class II or a Class I molar relationship