PubMed · 6380923
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D W Cohen. 1984. Future research needs.. https://pubmed.ncbi.nlm.nih.gov/6380923/
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Pairs of extracted premolar teeth were prepared with MOD cavities reducing the lingual cusp at its base to one of five widths: 1.25-2.25 mm. One of each pair was then restored with one of five adhesive restorative techniques and the weakened cusp of both teeth fractured by a force applied to the cusp at an angle of 30 degrees to the long axis of the tooth. At all cusp widths a layered restorative technique in which the cavities were filled to the enamel-dentine junction with glass-ionomer cement and the enamel replaced by composite, reinforced the weakened cusp more than the other restorative materials tested. This combination of materials to reinforce weakened cusps is worth considering as a cost effective alternative to removing the cusp entirely and making a crown or protecting the cusp with a cuspal coverage gold inlay.
The mucilage 'phenomenon' of marine waters, a sporadic but massive accumulation of gelatinous material at and below the water surface, can create serious environmental and economic problems. To address these problems, we must understand better the causes of the phenomenon, its modulation by environmental factors and its adverse effects on ecosystems. In the context of an improved understanding, this brief review describes the means to characterize mucilage types and mucilage aggregates in their native condition, or as close to native as state-of-the-art technology will permit. Biological, chemical and physical factors interact to determine mucilage 'speciation' and thus the specific properties of mucilaginous materials. These factors and their interactions are described briefly in relation to the molecular biology of mucilage synthesis, the formation of submicroscopic 'particles' of mucilage and the morphology of mucilage aggregates. To facilitate current attempts to relate mucilage fine structure to the macroscale morphology of large aggregates (e.g., as found in the Adriatic Sea), attention will be focused on the 'fibril', a ribbon-like colloid rich in polysaccharide molecules. Such colloids (submicrometre particles) present many morphotypes which are identifiable by transmission electron microscopy; several fibril types appear as basic structural units in many kinds of mucilage aggregates in aquatic ecosystems. Attention will also be focused on (1) the problems of coping with analyzing mixtures of highly-hydrated, physically-unstable materials and (2) the detection, assessment and minimization of colloid instability artifacts which have confounded morphological analyses of mucilage aggregates in the past.