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J Ahlgren

Publications and source records attributed to J Ahlgren.

At least 37 records · Page 2Linked to original sources
PubMed1985

An electromyographic analysis of the temporalis function of normal occlusion.

Electromyographic (EMG) activity was recorded from the anterior, middle, and posterior regions of the temporalis muscle in ten subjects with normal occlusion of the teeth and with the mandible at rest and during exertion of increased biting force, using bipolar intramuscular electrodes. Results show that the posterior part of the temporalis muscle maintains the mandibular posture. Although there is no statistically significant difference in EMG recordings between the three divisions of the temporalis muscle during intercuspal biting, individual variations in EMG pattern exist. During exertion of increased biting force the EMG activity increases proportionally in all parts of the muscle. During retruded biting force the posterior temporalis predominates. The EMG activity of the temporalis muscle is correlated to the form and position of the mandible.

Action Potentials↗
PubMed1982

Changes in length and torque of the masticatory muscles produced by the activator appliance. A cephalometric study.

The purpose of this study was to measure cephalometrically the change in muscle length and torque of the masticatory muscles produced by an activator appliance. The study was based on 10 orthodontic cases with distoclusion. Muscle length and force arm (leverage) were measured on two lateral cephalometric roentgenograms of each subject, one with the teeth in centric occlusion and one with an activator between the teeth. The construction bite of the activator was taken with the mandible repositioned 2-3 mm below and 5-6 mm ahead of resting position. It was found that the temporal masseter and medial pterygoid muscles increased 5-15% in length whereas the lateral pterygoid decreased 25% in length with the activator in place. The effect on the force arm on the temporal muscle was small, a decrease of 3-6%, but that on the masseter was much more dramatic, a decrease of 21-22%. Thus, as far as the torque of the temporal muscle is concerned, the small decrease in force arm is well compensated for by the increased muscle tension due to the stretching by the activator. The clinical significance of the findings for obtaining the best construction bite of the activator is discussed.

Activator Appliances↗
PubMed1978

Early and late electromyographic response to treatment with activators.

An EMG analysis of twenty Class II cases treated with activators shows that: 1. During daytime use of activators, the protractor muscles of the mandible are stimulated, while the retractors are inhibited. 2. During nightime use of activators, no functional stimulation can be recorded. The activator appears to be operated mainly by tissue stretching and the accompanying elastic rebound. 3. Before treatment, as well as after the treatment, Class II cases show a balanced EMG pattern during closure in the intercuspal position. 4. A narrow upper arch should be expanded before treatment in order to avoid occlusal interferences and to make it easier for the lower arch to adapt itself to a protruded position.

Activator Appliances↗
PubMed1977

Metallic implants as growth markers in infants with craniofacial anomalies.

The purpose of the study was to test the retention of metallic implants in bone tissue for evaluation of early facial growth patterns in patients with craniofacial malformations. Implants were inserted in 51 patients (age range: 1-17 months) with different diagnoses, the majority of them with various types of cleft lip and/or palate. Seven positions in the maxilla and four in the mandible were employed. Roentgencephalometric follow-up examinations were carried out at various stages up to the age of about three years. The results indicated that the frequency of implants firmly retained within the bone decreased with time depending on the craniofacial deformity and the implant sites. Stability seemed most critical in positions close to the alveolar processes where more than one-half of the implants inserted were dislocated or lost at the three-year follow-up. For the maxillary implants the patients with bilateral cleft lip and palate displayed the highest failure rate. This investigation did not support continuation of the implant method in infants as used in the present study.

Cephalometry↗
PubMed1974

[Orthodontics].

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History, 20th Century↗