PubMed · 5274594
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J J Messing. 1970. New developments in dentistry.. https://pubmed.ncbi.nlm.nih.gov/5274594/
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OBJECTIVE: To design, fabricate, and perform preliminary in vitro testing of a portable, hand-held, three-dimensional (3D) dental X-ray system using options unique to Tuned-Aperture Computed Tomography (TACT). The design allows for task-specific positioning over an unlimited range of user-selected angles and incorporates an integrated laser guidance system to constrain the focal-object distance. METHODS: A prototype system was fabricated consisting of an extremely lightweight X-ray source cantilevered from an aluminum gunstock-type handle to which a transparent radiation scatter shield was attached. Aiming was facilitated by task-specific visual cues used in conjunction with a spherically shaped radiolucent alignment jig coupled to the tissues of interest. Proper range was assured by a laser-assisted guidance system. The image transducer was an extrinsically modified commercially available CMOS device. The irradiated patient was simulated by a DXTTR phantom. RESULTS: The prototype demonstrated automated display of radiographed intra-oral tissues in three dimensions from arbitrary projection geometries and simulated task-specific sequences. Uncontrolled movements between exposures produced no obvious degeneration of 3D image quality. The aiming system minimized technical errors from misangulation. All dental regions in the phantom were imaged without difficulty. Projected risk was observed to be within clinically acceptable limits. CONCLUSIONS: Task-specific 3D images can be generated from as few as three uncontrolled projections. Total exposures can be prorated to levels not greatly exceeding those required for conventional two-dimensional radiographs of comparable image quality. Predicted radiation risks lie well below existing guidelines for occupational exposure.
OBJECTIVE: The purpose of this study was to evaluate the influence of using the dental operating microscope (DOM) for detection of the mesiolingual (ML) canal orifice in extracted maxillary molars compared with unaided vision (no loupes or headlamps). STUDY DESIGN: Using a clinical simulation model system, we mounted 39 maxillary molars in a dentoform and placed them into a mannequin. After rubber dam placement and preparation of standard access, 2 attempts were made to locate the ML canal with unaided vision. Then the teeth were examined by using a DOM. Finally, all teeth were sectioned, stained, and evaluated with the DOM for actual presence of an ML canal. RESULTS: ML canal orifices were detected in 20 of the teeth with a sharp explorer and mirror. In the remaining teeth, 12 ML canal orifice were located by using the DOM. Qualitative nonparametric comparisons were used. CONCLUSIONS: The results of this study indicate that the DOM provides increased opportunity for the dentist to detect canal orifices.