. The science and practice of dental surgery. ay occur in the positionof the mandilile in relation to the lower teethand to the facial contour, but in pure examplesof superior retrusion these small variations are only of academic mterest, and do not affect thesalient features of the deformity (see Figs. 216,217). The cause of this medial misplacement and contraction of theentue upper arch isobscure. In manycases it is clearlyconnected withnasal stenosis andconsequent imper-fect expansion andgrowth of themaxilla (retrogna-thism), and in facta condition of openbite due to thesame cause is oftenc
. The science and practice of dental surgery. ay occur in the positionof the mandilile in relation to the lower teethand to the facial contour, but in pure examplesof superior retrusion these small variations are only of academic mterest, and do not affect thesalient features of the deformity (see Figs. 216,217). The cause of this medial misplacement and contraction of theentue upper arch isobscure. In manycases it is clearlyconnected withnasal stenosis andconsequent imper-fect expansion andgrowth of themaxilla (retrogna-thism), and in facta condition of openbite due to thesame cause is oftencombined with theother (155, p. 337)well remarks : Ifthe difficulty ofbreathing, even ofmouth - breathing,be very great owingto adenoids, en-larged tonsils, orenlarged lingualtonsUs, the child\\ill not merelydrop the jaw inter-mittently, but willconstantly hold themandible down-wards and forwardsThus the mandibular arch by muscular action entirely escapes from the containing maxillary arch, and a maxilla of stimted growth and. Fifi -INjitiaits ui shown in Fig. 22l.);treatment; B, after treatment. tore compressed by mouth-breathing is opposed bya full-grown mandible whose horizontal ramusmay have been compressed by excessive muscularaction (mylo-hyoids) and by excessive lateralpressure. All this means inferior protrusion. 133 The appearance of protrusion is accentuated onclosing the teeth, as in edentulous old people. Case attributes the evil to extraction of thefirst permanent molars. No doubt this is afruitful cause of maxillary contraction, but itis difficult to see how upper incisors that havefully erupted in normal labial occlusion with thelower will be induced to fall back as the resultof such interference. In eases of deficientanterior development when the upper incisorsare already in lingual occlusion with the lower,extraction of the first permanent molars will,of course, intensify the evil and produce an ex-tremely contracted upperarch. However, t
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdentistry, bookyear19
