This method of finishing gives to the filling a perfect metallic lustre, which under some circumstances, is objectionable. Two other methods are in use: After the burnisher has been applied, as above, the buff or tape, with rouge, may be employed, by passing it rapidly over the filling, till the metallic lustre is destroyed, or deadened, so as not to reflect the light as before, thus leaving a very desirable finish; and the other method is, to stipple over the surface of the burnished filling with the end of a piece of hard wood, sandalwood is recommended,-charged with finely-pulverized pumice. This gives a beautiful, velvet-like surface, and is applicable to fillings in the anterior portion of the mouth, where they are exposed to view. Rotten-stone, applied either with the buff or with hard wood, imparts a finish which, although a little different, is equal to any of the others.

For finishing, some operators prefer to cut and polish, instead of filing, stoning or burnishing. But neither so good nor so fine a finish can be effected in this way, and it is probable that economy of time and labor, especially the latter, suggested the method. The introduction and use of the corundum cones and disks, cones of Hindostan and Scotch stone, and the wood cones and buffs (represented on pp. 113, 114), all to be used with the dental engine, greatly facilitate the work of finishing, and perhaps accomplish it

better; but great care should always be exercised in the use of these implements. In all cases the filling should have a distinct and definite margin; the gold should be trimmed off quite up to the border of the cavity, by passing round it a small sharp instrument, so as to detect and pare down any portion that might overlap the tooth; for if overlapping portions ‘are permitted to remain, foreign substances will lodge beneath, and induce decay. Neglect in this particular has occasioned the loss of thousands of teeth that otherwise might have been saved. This direction does not apply to those cases elsewhere mentioned, in which it is recommended to form a thick, firm overlapping portion, for the protection of a thin febrile border.

The subject of finishing is almost entirely overlooked by very many operators, but by the neat and skilful it is esteemed of sufficient importance to demand as great labor and pains as any other part of the work.

CHAPTER VII.

CLASSIFICATION OF DECAYED CAVITIES.

THE following classification of decayed cavities in the teeth, though from the very nature of the subject imperfect, will be found sufficiently accurate to aid the dental student and the practitioner. It is based primarily on the position of the cavities, and secondarily on the extent of the decay,-the classes having reference to the former and the modifications to the latter. The classes are numbered according to the accessibility of the cavities, beginning with those most easily approached and operated upon, and the modifications according to the extent of the decay, beginning with the smallest and simplest in form.

FIRST CLASS. Simple central crown cavities in the molars and bicuspids.

1st Mod.-Extension of the decay along one or more fissures or depressions.

2d Mod. Two decays in close proximity on the same crown, which may be formed into one cavity for filling.

SECOND CLASS.-Cavities in the buccal and palatal surfaces of the molars and bicuspids; and in the labial and palatal surfaces of the cuspids and incisors.

better; but great care should always be exercised
the use of these implements. In all cases the fill
should have a distinct and definite margin; the
should be trimmed off quite up to the border of
cavity, by passing round it a small sharp instru
so as to detect and pare down any portion that
overlap the tooth; for if overlapping portio
permitted to remain, foreign substances will lo
neath, and induce decay. Neglect in this pa
has occasioned the loss of thousands of te
otherwise might have been saved. This
does not apply to those cases elsewhere n
in which it is recommended to form a thick,
lapping portion, for the protection of a t
border.

The subject of finishing is almost en looked by very many operators, but by skilful it is esteemed of sufficient impo mand as great labor and pains as any the work.

he

Superity and

jur, and --and one

nination of

le

vulether

hat an

t to the

odgment

into them etained till

the nature of vity, which, of es the cavity is a comparatively lice being the same meter larger at the h a considerable porssions on the crown is instances, however, the .ch larger within than at decay is found to burrow I more rapidly than in any there is an imperfect union the dentine. In other in

ns to expand uniformly as it