A practical treatise on the technics and principles of dental orthopedia and prosthetic correction of cleft palate . perfectly correspond, and that certain teethdeviate slightly from the perfect line. Theincisors are arranged with their cutting edgesforming a continuous curved line from cuspidto cuspid, and this line is continued over thecusps of the cuspids and the buccal cusps ofthe bicuspids and molars to the distal surfaceof the third molars. From the first bicuspidto the third molar the lingual cusps of theseteeth form a second line of elevations. Be- 61 62 PART III. BASIC PRINCIPLES OF P
A practical treatise on the technics and principles of dental orthopedia and prosthetic correction of cleft palate . perfectly correspond, and that certain teethdeviate slightly from the perfect line. Theincisors are arranged with their cutting edgesforming a continuous curved line from cuspidto cuspid, and this line is continued over thecusps of the cuspids and the buccal cusps ofthe bicuspids and molars to the distal surfaceof the third molars. From the first bicuspidto the third molar the lingual cusps of theseteeth form a second line of elevations. Be- 61 62 PART III. BASIC PRINCIPLES OF PRACTICE tween these two, the lingual and buccal cusps, there is a continuous but irregularvalley, or sulcus. The lower teeth are arranged similarly but on a slightly smaller curve, sothat the line of the ellipse, which falls on the buccal cusps of the upper bicuspidsand molars, will fall upon the buccal surfaces near the gum on the lower teeth(Fig. 5). Therefore in occlusion the upper teeth project a little to the labial andbuccal of the lower at all points of the arch (Fig. 6). The incisors and cuspids Fig. occlude so that the cutting edges of the lower incisors and cusps of the cuspidsmake contact with the lingual surfaces of the similar teeth of the upper jaw neartheir cutting edges (Fig. 7). In this, however, there is much variety within thelimits of a normal occlusion. Sometimes the lower incisors strike the lingual sur-faces of the upper near the linguo-gingival ridge, and may strike at any pointbetween that and the cutting edges. In abnormal occlusions the lower incisorsmay miss the upper, striking tlie gums posterior to them, or they may occludeanterior to the upper incisors. The broad cusped occluding surfaces of the bicus-pids and molars of the opposing dentures rest on each other in such a way thatthe lingual cusps of the upper teeth fit with more or less accuracy into the gen-eral sulcus formed between the buccal and lingual cusps of the lower teeth. Thebuccal r
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