. The science and practice of dental surgery. olar cusps, for the lower jaw to move forward and allow the first permanent molars to achieve a normal occlusion (see Fig. 236). Harold Chapman (46), in anexcellent study of the decidu-ous dentition, expresses hisbelief that the discrepancybetween the medio-distal widthof the upper and lower molarsis greater than 14 mm., andthat the distal margin of thesecond lower is but little if atall anterior to the distal marginof the second upper deduces from this that thefirst lower permanent molarmust move forward more thanthe upper molar to produc
. The science and practice of dental surgery. olar cusps, for the lower jaw to move forward and allow the first permanent molars to achieve a normal occlusion (see Fig. 236). Harold Chapman (46), in anexcellent study of the decidu-ous dentition, expresses hisbelief that the discrepancybetween the medio-distal widthof the upper and lower molarsis greater than 14 mm., andthat the distal margin of thesecond lower is but little if atall anterior to the distal marginof the second upper deduces from this that thefirst lower permanent molarmust move forward more thanthe upper molar to producenormal occlusion. However,it is probable that such examples cannot beregarded as normal, and that in any case thedownward and forward rotatory movement of thefirst upper permanent molar during eruption willgenerally ensure locking of the cusps with thelower. It should be remembered that the lower lowt 138 usually, though not always, erupts first. Theearly development of post-normal occlusion inconnection with tlie differences m size between. for treatment for such young children, whenso much depends upon the character of themdividual. An attempt should usually be madeto remedy as soon as possible such grossdeformities as those just described. Improved knowledge of the aetiology ofabnormalities of occlusion tends to show withincreasing force the importance of early treat-ment. Only a few years ago arguments weredirected to show that treatment should not Fig. 231.—Skull sliowing post-normal occlusion oflower deciduous molars. (Harold Chapman :Trans. ; Denial Record.) the deciduous and permanent teeth is discussedby Simms (141). As regards other gross deformities PatonPollitt (131) has recorded a very rare case ofpre-normal occlusion (see Fig. 237). Cases of buccal and lingual malocclusion areoccasionally seen. An interesting example ina boy of five occurred in the writers ex-perience ; the lower arch was deflected tothe left, and the left side was in buccalocclusion w
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdentistry, bookyear19
