PRACTICAL CONSIDERATIONS : THE MOUTH. 1591 



frequent hyperaemia due to the vascularity and the warmth and moisture of the region, 

 together with slight but repeated trauma during mastication. The gingivitis of 

 scurvy or of purpura is merely a local evidence of a constitutional condition, and is 

 hemorrhagic rather than inflammatory. 



During dentition the resistance of the gums may cause backward pressure upon 

 the nervous and vascular supply of the pulp of the tooth, giving rise to some pain and 

 sometimes to grave reflex disturbances, especially in infants. The insensitive gum 

 then becomes exceedingly tender and is swollen and cedematous. The wide-spread 

 relations of the fifth nerve render long-continued irritation of its dental branches dan- 

 gerous. "Lancing" the gums is the obvious remedy. It is especially apt to be 

 needed over the molars and cuspids, and the lines of incision should be planned so as 

 to release fully the presenting surfaces of those teeth. 



The Teeth. Alveolar Abscess. The line of penetration in dental caries is 

 often in the direction of the pulp, through which infection extends to the "apical 

 space' ' between the root of the tooth and its socket, containing the vessels and nerves 

 and some loose connective tissue. This space soon becomes filled with pus, the cavity 

 enlarges, and reaches the compact bone on the surface of the alveolus (the density 

 of which impedes the process somewhat) ; but finally the bone is perforated, usually 

 through the thinner external or buccal wall of the alveolus. The periosteum usually 

 yields opposite the gum immediately over the apex of the tooth, where it is reinforced 

 by mucous membrane only. If the root of the tooth is a long one or the abscess 

 has gone deeply into the bone, the pus may reach the periosteum at a point where it 

 is supported by the muscular and fibrous tissues of the cheek. The pus may then 

 strip the periosteum from the bone so as to cause extensive necrosis. This is less 

 likely to occur in the alveolus of the upper jaw or in the hard palate, on account of 

 their free blood-supply derived from several sources. In cases of this type in either 

 jaw, a sinus followed by a depressed, adherent, and disfiguring cicatrix is liable to 

 result (Rough ton). Alveolar abscess is also influenced in its course by the situation 

 of the particular tooth involved. In the maxilla, abscesses connected with the canines 

 or incisors may point into the nasal cavity or on 



the under surface of the hard palate. The pus FlG - I 3S I - 



is more likely, however, to descend by gravity A 



alongside of the root to the edge of the gum, or 

 to follow the canal of the root into the pulp-cavity. 

 Abscesses connected with the upper molars, es- 

 pecially the first, or, more rarely, those in relation 

 to the cuspids, may point in the antrum. They 

 occasionally open on the face in front of the an- 

 terior border of the masseter. The relation of 

 the apex of the root to the mucous membrane of 

 the gum often determines the point of opening. *, 



If the apex in the case of the lower teeth is above, 

 or in that of the upper teeth is below the line of 

 reflection of the mucous membrane from the 

 cheek to the gum, the abscess tends to point in 

 the mouth. If the contrary is the case, pointing 

 on the face or neck may result. 



Tn wkli-tlis trip firc;t tpptri pvriihit malfnrma Characteristic teeth of inherited syphilis. 



in Sypmm me ma- A upper permanent central incisors deeply 



tions characteristic of perversions of nutrition Or notched; lateral incisors show no defect; right 



r n . r . i rr .1 canine has deep notch ; exposed dentine has 



01 inflammation OI the gums Sufficiently Severe tO become discolored. B, upper incisors onlv re- 



affprt trip h1nr>H-<;iinn1v to trip tontri-;ar^ Tfip cently erupted ; central notch marked out but 

 supply I not yet cleared OHt by breaking away of unpro- 



enamel may be deficient, Opaque Or chalky, the tected dentine; four lower incisors present peg- 

 j rf r i, .i .* i like excrescences due to loss of enamel and 



dentine soft or friable, the teeth irregular in size exposure of dentine. (Hutchinson.) 

 and uneven in position. 



The permanent teeth may show the same general aberrations as to growth and 

 nutrition that are produced by stomatitis from digestive derangements or from local 

 irritation. After mercurial stomatitis, for example, the teeth are irregularly outlined, 

 horizontally seamed, scraggy, malformed, deficient in enamel, separated too widely, 

 and dirty yellow in color. 



