Dental materials: 1979 literature review Part II

This paper, which is presented in two parts, reviews the work on dental materials published in 1979. Included in Part II are sections on impression materials, model, die and investment materials, waxes, acrylic resins, denture base polymers, soft lining materials and tissue conditioners, cast and wrought dental alloys, ceramics, implants and, finally, corrosion. Part I included sections on dental biomechanics, fissure sealants, cements, amalgam, composite filling materials, endodontic materials and microleakage.     

The nuclear imperative the Crookshank lecture,1984

The overwhelming destructiveness of thermonuclear weapons is illustrated by some simple comparisons with TNT—the ‘conventional’ military explosive. There is no theoretical upper limit to the size of an H‐bomb. It is recognized that nuclear war cannot be ‘won’ and must therefore be prevented; the current policy of ‘deterrence’ is examined and is seen to lead, not to a stable balance but, inexorably, to escalation. Richardson's mathematical analysis of conflict situations showed that automatic military responses to perceived threats generally lead to an escalating arms race. Human beings, however, need not behave like automata. Instead, they can try to see things from the standpoint of the adversary and seek ways of reducing instead of increasing tension. It is only if such saner responses are made that stability can be achieved. Scientists and technicians must not become so fascinated by the technological interest of weapons development that they ignore its ultimate purpose. Immanuel Kant summed up the conditions for peaceful and happy human society in his ‘categorical imperative’. His later essay On Permanent Peace showed that the same principle must apply between nations. Today this is the ‘nuclear imperative’ and we must throw off old habits of thought and resolve our conflicts in ways that do not include the threat of mutual extinction. Doctors should be in the forefront of this movement.     

The effect of reducing the number of clasps on removable partial denture retention

Retention to a master model of 10 nominally identical chrome-cobalt removable partial denture castings with standardized bilateral molar and premolar clasps engaging 0.25 mm (0.01 inch) undercuts and 10 castings with clasps engaging 0.5 mm (0.02 inch) undercuts was measured on an Instron testing machine. The retention of each framework was remeasured as the clasps were removed in one of two sequences. Differences between frameworks, number of clasps, and depth of undercuts were all significant. The order of removal of the clasps was not statistically significant. In a separate experiment the position of the dislodging force was found to be significant. It was concluded that the dislodging force was dependent on (1) the fit of the framework, (2) the depth of the undercut, (3) the number of clasps, and (4) its point of application.     

Dental materials: 1977 literature review Part I

This paper, which is to be presented in two parts, reviews the work on dental materials published in 1977. Included in Part I are sections on amalgam, casting alloys, acrylic resins, composite filling materials and fissure sealants. A review of the literature relating to impression materials, dental ceramics, model and die materials, cements, dental implants and dental biomechanics will be presented in Part II.