1592 HUMAN ANATOMY. 



The typical (and pathognomonic) syphihtic teeth — " Hutchinson's teeth" — are 

 the upper permanent central incisors. The type is observed in its perfection soon 

 after the extrusion of these teeth. The essential characteristic is a crescentic notch 

 (Fig. 1351,^^) in the free edge of the tooth, the anterior border of the notch being 

 bevelled from above downward and from before backward, — i.e., at the expense of 

 the anterior surface and border of the tooth. Typical Hutchinson's teeth are, fur- 

 thermore, reduced in length and narrowed, — "stunted ;" their angles are rounded 

 off, the lateral and inferior borders merging in a curved line ; they deviate from nor- 

 mality in direction, their axes being obliquely convergent, or more rarely divergent, 

 instead of parallel. 



The other surgical relations of the teeth and of the dental tissues which are of 

 chief importance are concerned with the new growths originating in dental elements. 

 The odontomata are divided by Sutton as follows, and the classification should be 

 remembered in studying the anatomical development of the teeth : 



(i) Persistent portions of the epithelial sheath (page 1561), taking on over- 

 growth, may give rise to an epithelial odontome (multilocular cystic tumor). (2) 

 Expansion of the tooth-follicle with retention of the crown or root of an imperfectly 

 developed tooth results in 3. follicular odontome (dentigerous cyst). (3) Hyper- 

 trophy of the fibrous tooth-sac causes a fibrous odontome, especially frequent in 

 rickets, which usually affects the osteogenetic fibrous membranes. (4) If the fore- 

 going hypertrophy occurs and the thickened capsule ossifies, a cementome results. (5) 

 (f this takes place irregularly, small malformed teeth — "denticles" — may form in 

 large numbers and occupy the centre of the tumor {compound follicular odontome^. 

 (6) Tumors of the root, after the full formation of the crown, are of necessity com- 

 posed of dentine and cementum only, enamel not entering into them {radicular 

 odontomata). (7) Tumors composed of irregular conglomerations of enamel, den- 

 tine, and cementum, and often made up of two or more tooth-germs fused together, 

 constitute composite odontomata. All these growths can be understood only by 

 careful study of the normal development of the teeth. They are rarely diagnosed 

 before operation, which is therefore in some cases needlessly severe. Sutton says 

 very truly, " In the case of a tumor of the jaw the nature of which is doubtful, par- 

 ticularly in a young adult, it is incumbent on the surgeon to satisfy himself, before 

 proceeding to excise a portion of the mandible or maxilla, that the tumor is not 

 an odontome, for this kind of tumor only requires enucleation. In the case of a 

 follicular odontome it is usually sufficient to excise a portion of its wall, scrape out the 

 cavity, remove the tooth if one be present, stuf! the sac, and allow it to close by the 

 process of granulation. ' ' 



The Roof of the Mouth and the Palate. — The mucous membrane cov- 

 ering the hard palate is so fused with the periosteum as practically to be inseparable 

 from it. It is dense, resistant, and comparatively insensitive. A vertical trans- 

 verse section of the roof of the mouth (Fig. 1294) shows the mucous membrane to 

 be thickest laterally and thinner in the median line. 



Cleft palate (page 1590) results from imperfect fusion between the horizontal 

 palatal plates of the maxillary processes of the first visceral arch. It is always in the 

 middle line. It may involve the soft palate and uvula. If it extends forward as far 

 as the alveolus, it follows the line between the maxilla and the premaxillary bone, 

 usually terminating in a harelip (page 1589) opposite the interval between the lateral 

 incisor and canine teeth. If it separates the maxillae on both sides from the pre- 

 maxillary bone, it is almost always associated with double harelip. 



The toughness of the muco-periosteum of the hard palate facilitates the forma- 

 tion of flaps in operations for the closure of such a cleft. In dissecting up the flaps 

 it is well to keep close to the bone and to avoid the descending or posterior pala- 

 tine branches of the internal maxillary artery. These vessels, on which the nutri- 

 tion of the flaps as well as of the bone depends, emerge from the posterior palatine 

 canal at a point on the line of junction of the hard and soft palates 8 mm. (^ in.) 

 anterior to the hamular process and a little to the inner side of the last molar tooth. 

 They nm forward in a shallow groove just internal to the outer border of the hard 

 palate. They are nearer to the bone than to the mucous surface, but their pulsa- 

 tions can often be felt by the finger. For these reasons incisions in uranoplasty 



