432 SIMPLE TUMOURS. 



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

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

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

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

 membrane, by which the cavity of reserve 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 papillaj of the natural teeth. 

 These irregular papilla3 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- 

 pletely block it up, as well as the posterior nasal opening. I 

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





Fig. 87 and Diagram, showing supposed development of dentigerous tumour 

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

 2, the gum. B, Further development of tooth, and of the eccentric folding of the 

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

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

 united, each tooth having a pulp cavity. 



they are enclosed in sacs or cysts; they, however, soon hurst 

 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, and detach them with 

 the forceps. 



