Simple method of boxing a final impression.
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Dental Impression Technique↗
Biomedical subjects
G K Mahanna
Publications and source records attributed to G K Mahanna.
Ultraviolet radiation-induced color shifts occurring in oil-pigmented maxillofacial elastomers.
STATEMENT OF PROBLEM: Oil-based pigments are added to a maxillofacial prosthesis either as base colorants present within the elastomer or as surface tints that are painted on with an adhesive. Color stability of the pigments and pigmented prosthetic materials on exposure to ultraviolet radiation are unknown. PURPOSE: This study measured DeltaE* color changes caused by ultraviolet radiation for materials colored with 5 oil pigments, applied either as base colorants (intrinsic) or surface tints (extrinsic) to a silicone elastomer. MATERIAL AND METHODS: One of 5 oil pigments was added to polydimethyl siloxane disks to serve as a base colorant (0.2 weight percent present throughout a 2 mm thick disk) or as a concentrated surface tint (2.0 weight percent concentrated in upper 0.3 mm thickness). Pigmented disks, along with pigment-only and elastomer-only control disks, were exposed to ultraviolet radiation for 400, 600 and 1800 hours. DeltaE* color changes were measured at baseline and for each time interval. RESULTS: Control samples underwent minimum color changes after 1800 hours (DeltaE* </= 2.0), whereas samples containing oil pigments as base colorants demonstrated a wide range of susceptibility to ultraviolet radiation, with the greatest changes occurring for pigments cadmium red, cadmium yellow, and yellow ochre (7.1 </= DeltaE* </= 9.4). Elastomers coated with the same oil pigments as concentrated surface tints demonstrated significantly lower color shifting after 1800 hours of radiation exposure (maximum DeltaE* = 4.2, P </= .05). CONCLUSION: Customizing a prosthesis with an oil-pigmented surface tint may reduce the incidence of color change, provided a sufficient amount of pigment is present.
Coloring Agents↗
Obturator prostheses after cancer surgery: an approach to speech outcome assessment.
PURPOSE: This article describes a speech assessment protocol for patients using either obturator prostheses or speech aid prostheses for surgically acquired defects due to cancer of the maxilla and/or soft palate. METHODS: This protocol is structured according to the executive summary of "Disability in America: Toward a National Agenda For Prevention" a report formulated by the Institute of Medicine that describes four levels of disorder: (1) pathology, (2) impairment, (3) functional limitation, and (4) disability. Assessment instruments included (1) the Sentence Intelligibility Test to measure the rate and understandability of speech, (2) a speech physiology system to measure appropriate separation of the nasal/nasopharyngeal and oral compartments, (3) a 13-point interval scale to rate speech nasality, and (4) a scale to rate self-perceptions of communication effectiveness. RESULTS: The results from two patients are reported to illustrate the outcome assessment protocol.
Disability Evaluation↗
Cancer in the differential diagnosis of orofacial pain.
The clinician must maintain an awareness that at some time a patient may present in their busy dental practice with a chief concern of dental, sinus, or TMD-like pain that, in fact, is of cancer origin. The question remains if an earlier diagnosis can be established in cases similar to those illustrated. It is mandatory that a thorough medical and dental history be taken by all health care practitioners along with a systematic and comprehensive examination when addressing head and neck pain. This includes careful examination, including inspection and palpation, of the oral and extraoral structures and the cervical lymph nodes at regular intervals in all patients but especially in those who are at high risk. History of smoking and alcohol use is of particular concern. Early head and neck cancer is usually symptomatic. Persistence in applying this practice philosophy is imperative.
Carcinoma, Squamous Cell↗
Color changes in dry-pigmented maxillofacial elastomer resulting from ultraviolet light exposure.
Five dry pigments and one maxillofacial elastomer were evaluated for color changes (delta E) resulting from prolonged exposure to two types of ultraviolet light. The elastomer, pigments, and pigmented elastomers were subjected to each ultraviolet light source for 400, 600, and 1800 hours, and delta E color shifts were determined. The unpigmented elastomer underwent minimally perceptible color change after 600 hours of exposure to both types of ultraviolet light. Two pigments underwent substantial color change after 400 hours, whereas the remaining three pigments remained color stable after 1800 hours. It was concluded that for the materials tested, early color changes in a prosthesis may be the result of degradation of certain ultraviolet light-susceptible pigments, whereas longer term color shifts may be caused by color changes within the elastomer.
Analysis of Variance↗
A cast orientation index.
This article describes a technique that allows multiple master casts to be precisely oriented to the same path of insertion and withdrawal. This technique is useful in situations where multiple fixed prosthodontic preparations require surveyed restorations and a single master cast is not available.
Dental Articulators↗
Cone positioning device for oral radiation therapy.
This article describes the fabrication and modification of a peroral cone-positioning device. The modification provides added cone stability and prevents tongue intrusion into the radiation field. This device provides a repeatable accurate cone/lesion relationship and the fabrication technique is simplified, accurate, and minimizes patient discomfort.
Humans↗