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Biomedical subjects

S J Chaconas

Publications and source records attributed to S J Chaconas.

At least 55 records · Page 3Linked to original sources
PubMed1976

The effects of orthopedic forces on the craniofacial complex utilizing cervical and headgear appliances.

1. A three-dimensional anatomic model of a human skull was produced with birefringent materials for photoelastic analysis. By means of photoelastic techniques during application of high-pull and cervical extraoral traction, stresses were visualized within the model. 2. Extraoral anchorage affected the position of the maxillary molar and its resulting alveolar development. Cervical headgear had a much greater tipping effect on the maxillary molar than did the high-pull headgear. Both appliances examined could produce stresses which may be transmitted to distant eraniofacial sutures. As opposed to high-pull traction, cervical pull in general stressed more areas and to a much greater degree. 4. The pterygoid plates of the sphenoid bone, the zygomatic arches, the junction of the maxilla with the lacrimal bone and the ethmoid, and the maxillary teeth were affected by both types of headgear. 5. Only cervical traction produced stresses at the frontal process of the maxilla and the Zygomaticofrontal suture. 6. There were two findings which had not been previously reported: First, cervical traction tended to open the palate in the posterior region. Second, high-pull traction produced compressive stresses at the junction of the right and left maxillae inferior to the anterior nasal spine.

Facial Bones↗
PubMed1976

Posttreatment and postretention changes following orthodontic therapy.

This investigation was performed to determine the changes which occurred in treated orthodontic cases out of retention. The material consisted of 103 cases, of which 74 cases were treated nonextraction and 29 were treated with the extraction of four first premolars. The treatment was accomplished by the full-banded edgewise bioprogressive technique. Five measurements were taken: intercanine, inter-first premolar, intersecond premolar and inter-first molar widths, and incisor to molar distance. The measurements were made on the mandibular arch of the pretreatment, posttreatment, and prostretention casts. The postretention model was obtained a minimum of one year after all retaining devices were removed with an average of 5.2 years. The following conclusions were drawn from the changes in dimensions: 1. The intercanine width was expanded during treatment, but had a strong tendency to return to or close to its original pretreatment width in both nonextraction and extraction cases. 2. The inter-first premolar width showed the greatest treatment increase in width with only a minimal amount of postretention decrease. 3. The second premolar width for nonextraction cases showed a significant amount of increase with a slight tendency for postretention decrease. 4. The second premolar width for extraction cases showed a decrease with treatment and a slight continued decrease postretention. 5. The intermolar width of nonextraction cases showed a significant increase in width with treatment. The extraction cases showed a significant decrease with treatment. However, there were no changes in either extraction or nonextraction cases postretention. 6. The incisor to molar distance decreased with treatment and had a slight tendency to continue to decrease postretention.

Bicuspid↗
PubMed1975

Effects of force direction on supporting bone during tooth movement.

Photoelastic stress analysis by means of simulated load application on model structures was used to visualize the forces that are induced within the supporting bone structures during various tooth movements. A comprehensive picture of the stress patterns produced by these forces, in addition to the degree of stress distribution, was obtained. The results of this study are relevant to the basic tooth movement procedutes that are used by the clinician in general practice.

Alveolar Process↗
PubMedDate not supplied

A comparison of athletic mouthguard materials.

The development of protective mouthguards resulted from extensive injuries during participation in contact sports. This has produced a dramatic decrease in the incidence of injuries to the orofacial complex. Numerous materials and techniques have been used for mouthguard fabrication. The purpose of this investigation was to make an in vivo comparison of various thermoplastic mouthguard materials. Mouthguards were fabricated upon maxillary models of 40 members of the UCLA football team. The mouthguards were made of the following materials: poly (vinyl acetate-ethylene) copolymer clear thermoplastic; polyurethane; and laminated thermoplastic. Eleven measurements were taken for each mouthguard to demonstrate dimensional changes that occurred with wear. Statistical analyses determined differences between the types of mouthguards. The clear thermoplastic revealed less dimensional change than the polyurethane material. The laminated thermoplastic showed significantly less dimensional change than the other materials tested.

Football↗