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Biomedical subjects

M G Duncanson

Publications and source records attributed to M G Duncanson.

At least 55 records · Page 3Linked to original sources
PubMed1986

Contours of the edentulous palate.

Diagnostic casts were made of the palates of 123 patients who had complete dentures. Categorization of all cross-arch palatal forms yielded a distribution in which 93% showed some variation of a U-shaped palatal form, be it angular or mildly curved. Along the midline, 12% had steep anterior inclines, curved midpalatal regions, and curved posterior palates; 69% had moderate anterior inclinations, curved midpalates, and curved posterior palates; 12% had palates that were moderately inclined anteriorly, flat in the midpalatal section, and flat posteriorly. The remaining palates were predominantly flat in two of the three regions measured.

Cephalometry↗
PubMed1985

Effect of abutment mobility, site, and angle of impact on retention of fixed partial dentures.

Fixed partial dentures cemented to dies of adjustable mobility were subjected to repeated impacts at three different sites. Immobile abutments retained their prostheses longer than mobile abutments. Impacts that fell between the centers of rotation of the abutments were withstood longer than impacts that fell nearer the ends of the prostheses. This study failed to show a significant difference between the effect of impacts perpendicular to the occlusal plane and impacts angled 45 degrees toward the lingual plane. The results of this study suggest that (1) crowns that anchor rigid prostheses to mobile teeth require greater retentive ability than crowns on relatively immobile abutments and (2) occlusal impacts are best withstood when they fall on the areas of the fixed partial denture over and between the centers of rotation of the abutment teeth. If a fixed partial denture must withstand loading outside these areas, as is the case with cantilevered pontics and some tilted abutments, the retainer furthermost from the anticipated eccentric load must have exceptionally good retention.

Dental Abutments↗
PubMed1984

Compressive stress relaxation measurements of selected dental restorative composites.

Compressive stress relaxation measurements were performed on specimens of selected dental restorative composites. The relaxation modulus showed a linear dependence on the logarithm of time. The values obtained indicated that stress was dissipated more rapidly in dental composites than in enamel, but less rapidly than in human dentin.

Acrylic Resins↗
PubMed1983

Influence of preparation features on retention and resistance. Part I: MOD onlays.

Four variations of an MOD onlay preparation were studied for retention and resistance. Boxes were more effective than an isthmus in increasing retention value. The combination of boxes and isthmus showed the highest retention. The combination of boxes and isthmus also exhibited the highest resistance. There was no difference in resistance between boxes and the isthmus.

Crowns↗
PubMed1983

The effect of single plane curvature on half-round cast clasps.

The quality of retention produced by a half-round cast clasp is affected by its curvature in the plane of its flat side. Uncurved clasps and those that curve 90 degrees, 180 degrees, and 270 degrees become progressively stiffer. Conversely, as the radius of the curvature increases, so does the flexibility of the clasp.

Denture Design↗
PubMed1982

Comparison of bond strengths of polymethyl methacrylate and alpha cyanoacrylate.

A method of fabricating similar methyl methacrylate cylinders was used to produce specimens to test the bond strength of alpha cyanoacrylate and autopolymerizing methyl methacrylate. Each group was tested immediately and after storage in 37 degrees C water bath for 90 days. Statistical analysis supported the finding that the autopolymerizing methyl methacrylate produced a better bond even without undercuts or mechanical retention.

Chemical Phenomena↗