432 



SIMI'LL TUMOUK*-. 



fold in the lining membrane, and that in this cavity a papilla 

 is formed exactly in the same way as in that of a temporary 

 tooth. Novr, I look upon the formation of these dental tumours 

 as being due to Pome eccentricity in this folding of the lining 

 iiicmbrane, by Avhicii the cavity of resei-ve is made up of several 

 folds ; that these folds become eventually separated from each 

 other, forming separate cavities of reserve ; and that a papilla 

 becomes developed in each cavity thus formed in a manner 

 similar to those constituting the papillre of the natural teeth. 

 These irregular papillai become finally converted into irregular 

 teeth, which, for want of space in the mouth, are forced upwards 

 Into the antrum, and — as in the photo-lithograph — may com- 

 j»letely block it up, as well as the posterior nasal opening. I 

 have classified them as cystic tumours, as, in the first instance 



Fio. 87 and Diaj.Tain, eliowing supposed development of dentigerous tumour 

 A, 'Eccentric foldinjj of "cavity of reserve," 3 and 4 showing its two extremities 

 2, the i;um. Ji. Further development of tooth, and of the eccentric folding of tha 

 reserve cavity, the folds becoming separated from each other, each fold forming t\ 

 separate cavity. C, shows two real teeth removed from a tumour imperfectly 

 uniied, each tooth having a pulp cavity. 



thoy are enclosed in sacs or cysts ; they, hpwever, soon burst 

 through their investing membrane, and form a large tumour, 

 composed entirely of teeth, having a great variety of shapes, and 

 running in different directions. The teeth vary in size, some 

 "being very small, others nearly as large as a permanent molar; 

 each tooth has a pulp cavity, and is composed of the same 

 structures as the natural teeth. 



Should their removal be determined upon, it will be necessary 

 to trephine the superior maxillary sinus, an4_detach them with 

 the forceps. 



