Biomedical subjects
Publications and source records attributed to G Handel.
A new computerized system for jaw movement registration allows a finer diagnosis of TMJ clicks. We recorded jaw movements in patients where we detected reciprocal clicks during clinical examination. We found two different types of derangements: an anterior displacement of the disk (as described by Farrar and a posterior displacement of the disk (similar to description of Klett).
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To perform target orientated therapy simulators of condyle movements (CPS) have been introduced recently. It is believed to improve analysis of jaw by computer aided registration and evaluation systems (i.e. transformation of the true axis and jaw movements for use in articulators). Although the electronic evaluation systems helped to improve our understanding of the movements of the jaw, up to now the reproduction of physiological and pathological movements and their therapeutic changes have not been solved satisfactorily. The reason is sometimes miscorrection of system inherent projection errors. Additionally, numerical analysis and changes of the registered pathological movements are restricted to certain limits within the articulators for therapeutical purpose.
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Conventional imaging methods showing only one joint side are insufficient diagnostic tools for analyzing pathologic condyle paths. Although they demonstrate the effects of internal joint derangement, they fail to reveal the pathologic causes. Superior results are obtained by means of computer-assisted evaluation programs which allow simultaneous imaging of both joints in perspective.
Stereognathographic recordings were taken of the mandibular movements of 11 patients who had undergone conservative treatment for unilateral disk perforation. The results showed a significant decrease in the condylar inclination angle of the affected joints. Based on these values the condylar inclinations were increased in a condyle positioning simulator (CPS). This allowed production of individually correct occlusal splints. In all cases studied this splinting therapy eliminated pain and crepitus.
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Explore the source record for details and available documents.
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In a previous field study of how feedback on intoxication might affect an individual's decision to drive, it was found that a small sample of people were quite accurate in their recall of alcohol consumption. The accurate estimation of alcohol consumption clearly is of potential value in driving while intoxicated (DWI) prevention programs. However, because the finding of accurate recall is inconsistent with other reports in the literature, it was decided to replicate the testing with a larger sample. Randomly selected patrons leaving taverns and bars were asked to participate in a study, and individuals agreed to answer a consumption questionnaire and have their blood alcohol level (BAL) measured. Results indicated that subjects were very accurate in their estimates of consumption when self-reports were compared with Breathalyzer readings (r = .70, p less than .01). An additional trend of some interest was that men were apparently more accurate in their estimates of consumption than women even though they generally had higher BALs. The present study replicates and extends the earlier findings concerning the ability of college-age drinkers to estimate alcohol consumption in field settings accurately.
College-aged patrons leaving a drinking establishment were given feedback about their blood alcohol level (BAL): 24 were administered a Breathalyzer and were then read a statement on the consequences of driving with their BAL; 21 were shown a large chart and had to determine their own BAL from their weight and number of drinks consumed; and 21 were given no feedback. The two feedback groups were later collapsed. The subjects were also followed unobtrusively to determine whether they drove away from the premises. A total of 24 of the feedback subjects (47%) were legally intoxicated, but 83% of this group nonetheless drove after learning that they were legally intoxicated. In addition, when self-reports of consumption were compared with Breathalyzer BALs, a correlation of .82 was obtained.
PURPOSE: Artificial teeth made of acrylic resin or alloy are considered substitutes for rare caries-free human teeth in in vitro examinations. The purpose of this study was to compare the fracture strength and marginal adaptation of all-ceramic single crowns fixed to natural teeth with crowns fixed to artificial teeth after artificial aging. MATERIALS AND METHODS: The fracture force and marginal adaptation were investigated in 28 adhesively luted all-ceramic crowns on human molars of different sizes, as well as on alloy and liquid crystal polymer (LCP) artificial teeth. The fracture force was determined using a universal testing machine, and the semiquantitative marginal adaptation was examined using a scanning electron microscope, in both instances after simulating 5 years of clinical service. RESULTS: Fracture force was found to be significantly higher for crowns fixed on substitute materials (alloy = 1,838 N; LCP = 1,392 N) than for crowns on human teeth (888 N). No significant differences in marginal quality could be determined between the groups. All crowns showed marginal gaps of about 10% and perfect margins at about 90%. CONCLUSION: The high in vitro fracture values of all-ceramic crowns on artificial materials may lead to a misinterpretation of the tested restorative materials, overvaluing the material properties in a first preclinical estimation. Human teeth or materials with a comparable modulus of elasticity are therefore preferred in in vitro fracture tests.
PURPOSE: Clinical damage, such as the fracture or abrasion of composite veneers, may cause the loss of a fixed partial denture (FPD). Intraoral methods may help in repairing and therefore lengthening the life span of the restoration. The aim of this in vitro study was to evaluate an intraoral method of repairing fractured FPDs made of two different fiber-reinforced composite framework systems. MATERIALS AND METHODS: Shear bond strengths of a composite between two different fiber-reinforced composite frameworks were determined after five different mechanical surface treatments. A silicate-silane coating intraoral air-abrading system provided the most reliable bond strength values and was therefore used for treatment for the following veneer repair. The repair of 24 three-unit posterior FPDs was performed using a restorative composite resin. All FPDs were examined after simulating clinical service using thermocycling and mechanical loading. Fracture forces were determined for original FPDs and for FPDs after simulated intraoral repair. RESULTS: The fracture strength of all original FPDs was about 900 N. After repair, a maximum decrease in strength of about 15% was determined. FPDs that were extremely damaged by cutting the framework showed the lowest results, with values of about 450 N. CONCLUSION: The repair of the fractured veneer of fiber-reinforced composite FPDs provided good results and therefore may lengthen the life span of damaged FPDs. The repair of the fractured frameworks showed good results but can only be recommended for limited temporary use.
To restore the masticatory function after tumor surgery, 110 transmucosal intraoral implants have been inserted in 21 patients, and 26 percutaneous implants in a total of 9 patients for the stabilization of facial prostheses. While 12 of the intraoral implants had to be removed for lack of bony integration, the losses of the percutaneous implants for the stabilization of facial prostheses were exclusively due to tumor recurrences in the direct vicinity of the implants. Our previous results in the use of osseointegrated implants for the retention of restorative maxillofacial prostheses show a limited incidence of complications and give reason to expect long-term success in functional and esthetic rehabilitation. This method provides a decisive improvement in the quality of the life of tumor patients compared to the procedures used up to now.