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Biomedical subjects

J Dahan

Publications and source records attributed to J Dahan.

At least 19 recordsLinked to original sources
PubMed1989

Cephalometric changes in Class II, Division 1 cases after orthopedic treatment with the bioactivator.

The bioactivator is an orthopedic appliance that has been used for 20 years in the treatment of Class II, Division 1 cases. The evaluation of its therapeutic effects was performed in this study of 76 9- to 10-year-old patients (at the beginning of treatment). The treated subjects were separated into two groups: group A (bioactivator only) and group B (bioactivator plus headgear). Group C comprised 14 untreated subjects selected as controls. Various statistical assessments were made to separate growth phenomena from treatment effects. It appears that the bioactivator has an effect not only on the dentition but also on the skeletal structures. In both treated groups, the maxillary changes were related to an increased anterior vertical growth and a posterior sagittal growth. The addition of extraoral force helped to achieve a posterior rotation of the upper jaw. When only the bioactivator was worn, the mandibular changes were more vertical than sagittal. The lower jaw appeared more forward, however. When the bioactivator and the headgear force were used simultaneously, the therapeutic effects seemed to be more sagittal than vertical, as if the occipitally directed force vector inhibits or at least exerts a control on the downward growth tendency. Without being significantly different statistically from one to the other, the treated groups showed a marked improvement of the sagittal jaw discrepancy.

Activator Appliances↗
PubMed1986

Comparison of the reproducibility of EMG signals recorded from human masseter and lateral pterygoid muscles.

EMG recordings of the left and right masseter and lateral pterygoid muscles were repeated three times in 15 young adults to test the reproducibility of the signals. Two tests were made on the same day (morning and afternoon) and one test three days later (morning). Needle and hook electrodes were used for the masseter muscle and needle electrodes for the lateral pterygoid muscle. The superficial areas of recording were tattooed on the skin. An intra-oral approach was selected for the lateral pterygoid muscle. The subjects were asked to perform three definite tasks for the masseter muscle (intercuspid occlusion, maximum protrusion, and centric relation with a bite opening of 3mm) and two for the pterygoid muscle (maximum opening and maximum protrusion). The EMG signals were directly integrated, and root mean squares of the AC components were computed. The selection of the signals to discard possible artefacts was performed by displaying EMG and RMS outputs on a six-channel UV oscillograph. The selected RMS values were submitted to different analyses of variance to define additive and non-additive models of effects. The results may be summarized as follows: The between-day sessions showed more variation than the within-day sessions. The variations related to the method accounted for a very high percentage of the total variance (48.9%). The recordings with needle electrodes displayed a large percentage of the individual variation (masseter, 31.2%; lateral pterygoid muscle, 65.9%) and significantly lower values for the variations related to the session or the side of recording. The one-side recordings were more suitable for distinguishing the biological variations than were the bilateral ones.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1979

The functional compensation: an interceptive procedure in the mixed dentition.

Functional compensation, like the morphologic one which accompanies it, is to be encountered naturally in each system or organ. It facilitates the performance of the required activities in spite of the defectiveness of one or more of their biocomponents. If the pathologic forms of compensation or simply their perturbing effects are noticed early enough, deleterious and irreversible effects on growth and development of the orofacial zone may be avoided. Instead of simply supervising dental evolution or limiting intervention to early procedures (extractions) until the time for corrective treatment, we propose functional interception. Inducing a therapeutic compensation by removable appliances, this therapy aims to modify the equilibrium of displaying forces and to favor a more physiologic alveolar and sutural growth. The proposed appliances are able to intervene in the postural and dynamic position of the mobile organs in the oral cavity. They compensate their action; that is, they correct, complete, or replace it. The bimaxillary appliance is called bioactivator "biprax". Based simultaneously on the principles of the activator and bionator, it exploits a normal display of the two praxisms-speech and deglutition. Being worn day and night, it is able to guide efficiently the evolution of dental, alveolar, and even basal relationships. Its interceptive use does not interfere in any way with the onset of a corrective treatment in the adult dentition.

Activator Appliances↗