TEETH, BLOOD VESSELS 



334 



TEETH, DECALCIFICATION 



phorus. Some techniques are also pro- 

 vided under Teeth and Jaws and parts 

 of teeth : Enamel, Dentin, and Pulp. 

 Teeth, Blood Vessels (Boling, L. R., Anat. 

 Rec, 1942, 82, 25-32). Revised by L. R. 

 Boling, July 27, 1946. Two suspensions 

 are recommended: (1) cinnabar, 120 

 gms. ; gum arable, 40 gms. ; water, 160 

 cc. (2) cinnabar (red mercuric sul- 

 phide), 80 gms.; corn starch, 40 gms.; 

 10% formalin in physiological saline, 

 125 cc. Grind up the mixtures slowly 

 in a glass ball mill for 2 or 3 days, strain 

 through gauze, and use immediately. 

 Anesthetize a cat or dog with sodium 

 pentobarbital. Expose and ligate both 

 common carotid arteries. Perfuse the 

 head with physiological saline through 

 a glass cannula inserted in one carotid. 

 Incise the carotid of the opposite side 

 distal to the ligature and allow it to 

 bleed until clear saline appears when it 

 should be clamped. Open the jugular 

 veins and allow them to drain. As 

 soon as all blood has been washed from 

 the vessels of the head direct the sus- 

 pension through the same cannula by 

 means of a two way stop cock. Main- 

 tain a pressure of 120 mm. of mercury by 

 air pressure. Aid penetration by gentle 

 rhythmic pressure on a hand bulb in- 

 serted in the conducting system. When 

 injection of the mass is begun remove 

 the clamp momentarily from the op- 

 posite carotid to allow free flow of the 

 mass in all large arteries. This pro- 

 motes good injections of both right and 

 left sides from the single cannula. 

 After completion of the injection remove 

 the head and place in strong formalin 

 over night, then cut away the soft tissue 

 from the jaws and place the jaws inl0% 

 formalin in saline solution for several 

 days, wash, and decalcify in 5% nitric 

 acid. After decalcification dehydrate 

 thoroughly in graded series of alcohol and 

 clear in two changes of methyl salicylate. 

 Dissect away any bone interfering with 

 observation of teeth. This is best done 

 with a dental engine and round bur while 

 the specimen is immersed in clearing 

 fluid. Moisture or heat will cause 

 clouding of the specimen and must be 

 avoided. In addition to the desirable 

 color of cinnabar, is the radiopacity of 

 these injections; the course of all 

 macroscopically visible vessels may be 

 followed m roentgenograms before decal- 

 cification. The method also works well 

 on soft tissues. The first mass will pass 

 through all capillaries in a tooth and 

 fill both arteries and veins. Better 

 demonstration of arteries is obtained 

 with the second which has not been 

 found to pass through capillaries. The 

 use of formalin seems to aid in the reten- 



tion of the mass in the blood vessels and 

 to prevent the formation of gas bubbles 

 in the pulp cavity during decalcification. 

 Teeth, Decalcification: Details from Dr. 

 L. R. Boling, Washington University 

 (School of Dentistry). Revised by him 

 Dec. 16, 1950. 



Decalcification of teeth for the prep- 

 aration of histological sections presents 

 several problems not encountered with 

 other tissues especially if the surround- 

 ing bone and soft tissues are also pre- 

 served. The great difference in salt 

 content and organic matrix of enamel, 

 dentin, cementum, bone and soft tis- 

 sues makes difficult the preservation of 

 one while the others are being decal- 

 cified. 



Enamel, except in the most immature 

 portions of developing teeth, is entirely 

 destroyed by ordinary decalcification 

 methods. The organic portion of adult 

 enamel may be observed by the slow 

 decalcification of thin ground sections 

 under a cover slip (Chase, S. W., Anat. 

 Rec. 36, 239-258, 1927). The acid, one 

 per cent nitric, hydrochloric or sul- 

 phuric, or five per cent chromic, acetic 

 or citric, is run under a propped cover 

 slip over the section. Action may be 

 stopped at any point by substituting 

 water for acid and the remaining mate- 

 rial stained and mounted as de- 

 sired without disturbance. Boedeker's 

 method of "celloidin-decalcifying" is 

 also said to give good results (Funda- 

 mentals of Dental Histology and Embry- 

 ology, New York, The MacMillan Co., 

 1926, p. 223) and allows sectioning of the 

 organic remainder in any plane. See 

 Enamel. 



For the examination of sections of 

 whole teeth without enamel or for teeth 

 in relation to the bone of the jaws five 

 per cent nitric acid in water has been 

 found by most investigators to give con- 

 sistent results. Hydrochloric acid may 

 be used but causes too much swelling. 

 For delicate objects one to five per cent 

 nitric acid in 70 per cent alcohol may 

 prove superior. 



Excellent results have been ob- 

 tained with the use of formic acid ac- 

 cording to the technique of Morse, 

 J. Dent. Res., 1945, 24, 143-153 in the 

 decalcification of single human teeth 

 or teeth and jaws of small animals. 

 Two solutions are made as follows: 

 Solution A: 1 part 90% formic acid 

 C.P. and 1 part aq. dest., Solution B: 

 20 grams sodium citrate C.P. and 100 

 cc. aq. dest. At the time of use com- 

 bine equal parts of A and B. Change 

 solution daily until decalcification is 

 complete as shown by chemical test. 

 (See below.) When this method is 



