Biomedical subjects
Publications and source records attributed to A A Caputo.
A human mandible was duplicated in birefringent resin. The distribution and effect of occlusal forces within the mandible was demonstrated utilizing birefringent resin models compared to natural specimens. The results of this study reinforce those theories that assign function a major role in bone remodeling in the mandible. Further, the condyle is seen to be a stress-bearing structure.
A test technique is presented for evaluating metal-ceramic bond strengths. The test piece consists of a four-point loaded metal beam with porcelain bonded to the central tension side of the beam. The test produced failures at predictable locations and was able to differentiate between metal surface treatments.
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An anatomic photoelastic model of a human skull was constructed with the use of individual simulants for teeth, bone, and periodontal ligaments. The following effects of extraoral chin cup traction were observed: 1. Stresses were noted in the area of the pterygoid plates of the sphenoid bone due to the insertion of the simulated external pterygoid muscle. 2. Because of direct contact of the condyle against the posterior surface of the glenoid fossa, forces were seen to be transmitted to this anatomic area. 3. Stress trajectories followed the trabecular pattern of the anatomic configuration of the mandible. 4. Beginning at the apices of the incisor teeth, the stresses emanated through the body, the angle and retromolar triangle of the mandible, radiating in a posterosuperior fashion and concentrating at the neck of the condyle. 5. Selected sectioning of the mandibular model showed evidence of stress concentration at the lingual aspect of the angle and retromolar area as well as at the condylar neck at the level of the external pterygoid muscle insertion. The effects of orthopedic forces produced by an extraoral chin cup in this study are correlated with the histologic and clinical observations during the utilization of this appliance in the treatment of Class III malocclusion.
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.
Pins and posts retain restorations and protect remaining tooth structure; they are indispensable to conservative operative dentistry. Effective utilization of these pin-post systems requires application of proper biomechanical principles for each clinical situation. No one design will suffice in every case. A parallel, serrated, cemented device in a precise matched channel is the ideal combination of characteristics. When tooth morphology or heavy function require increased retention, it may be achieved by increasing pin-post length, diameter, and number or by utilizing the resilience of dentin. However, the dentist must be aware that the price for more retention is the increasing risk of damaged tooth structure. Optimal long range results will be obtained by utilizing pins and posts in conjunction with veneer types of restorations. When used in this manner, they will save many teeth each year and simultaneously reduce the rate of failures.
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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.
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