A practical treatise on the technics and principles of dental orthopedia and prosthetic correction of cleft palate . ensiveretrusions and protrusions. This was originally named the contouring appara-tus. It was afterwards discovered that this same principle of applying force tothe teeth, according to the law of levers of the third kind, was quite as applicable 166 CHAPTER XX. MODERN PRINCIPLES AND METHODS 167 for bodily lingual or retruding movements of the front teeth; and in recent yearsthis same mechanical principle has been extensively employed for bodily move-ments of the teeth in every d
A practical treatise on the technics and principles of dental orthopedia and prosthetic correction of cleft palate . ensiveretrusions and protrusions. This was originally named the contouring appara-tus. It was afterwards discovered that this same principle of applying force tothe teeth, according to the law of levers of the third kind, was quite as applicable 166 CHAPTER XX. MODERN PRINCIPLES AND METHODS 167 for bodily lingual or retruding movements of the front teeth; and in recent yearsthis same mechanical principle has been extensively employed for bodily move-ments of the teeth in every direction. In fact, no teeth were ever moved bodily,except through the application of this principle of force, which consists in theestablishment of independent points of fulcrum and power in relation to thealveolus or area of work. Even that addition to our technic principles of tor-sional force for the bodily movement of teeth presented recently by Dr. Angleand exemplified in his new pin and tube and bracket and ribbon appliances,is reducible in its direct action to that of a lever of the third kind. Fig. The first impressions of this case—the plaster casts of which are shown inFig. 105, were taken September 27, 1916, and are those of a miss thirteen years ofage. Both right and left sides of the denture were so alike in buccal occlusion, it isunnecessary to show but one side. As will be observed by an examination of thebuccal occlusion, the upper denture is sHghtly distal to normal, and the upperincisor teeth, though appearing to be prominent at their occlusal edges, distinctly 168 PART V. PRIMARY PRINCIPLES OF PRACTICE show by the retruded facial outlines that they are quite labially inclined from deep-ened incisive fossae. The apparent prominence of the upper incisor crowns isenhanced by the retruded position of the lower incisors, which was caused by thecriminal extraction of a lower lateral incisor which happened to erupt—as incisorsoften do—in lingual malalign
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