Animal studies on dental transplants

ANIMAL

STUDIES

ON DENTAL

TRANSPLANTS*

D. E. WAITE, D.D.S., M.S., IOWA CITY, Iowa LINICAL case reports are constantly appearing in the literature on both autogenous and homologous transplants. It is important. to evaluate the transplant not only from a “take” standpoint, but also with regard to how well the transplanted tooth fits into the occlusion and maintains contact with the proximating teeth. The tooth also should be able to withstand the normal stresses of mastication. In consideration of homologous transplants, one is immediately confronted with the problem of storage and the possibility of establishing a tooth bank. If homologous transplants prove to be successful and feasible, this would greatly increase the availability of selected teebh for transplant purposes. Experimentally, we have been storing the donor teeth in both saline and Ringer’s solutions. Microscopically, we have found cellular change within the dental pulp showing various degrees of autolysis as early as six hours following t.he removal of the tooth from the donor (Fig. 1). Because of this limitation, experimental work was begun on a freezing technique for storage of teeth. The reasoning behind this is much the same as that for freezing any type of tissue. It has been proved scientifically that the active vitality of tissue requires chemical activity which, in turn, depends on molecular movement. It has been shown that, when t.he temperature is lowered, molecular movement is diminished. Another requirement of chemical activity is the presence of water in the tissue. Therefore, it is felt that, by removing water and lowering temperature, it may be possible to preserve the tooth in storage for a longer period of time. It was on these established findings that our experimental work was based. However, it is d3Xcult to handle a tooth in this manner because of the presence of both soft and hard Gssues. This is particularly difficult because of the difference in the coefficient of shrinkage and expansion of the two tissues. @or example, when freezing with any of the faster methods, such as iso-pentane, dry ice pentane slush, and liquid nitrogen, cracking of the enamel

C

From *The Association vania) and Committee

the Department of Oral Surgery. State University of Iowa. detailed results of this work were reported at the 1955 meeting of the International Pennsylfor Dental Research by Drs. C. E. Staly (who is now practicing in Eri Drs. Staly and Waite are further indebted to the Nov “r ce Award D. E. Waite. for selecting their Daper for the Novice Award.

40

ANIMAL

STUDIES

ON DEXT:\L

TRANSPLANTS

I-:

occurs. When dry ice in alcohol slush was used, however, the enamel was 1101 injured. Prior to freezing, all specimens were subjected t.o various (!()tl(~ent~l*iltions of glycerol. The purpose of this was to exl.ract water content from this pulp tissue. If this is not done, crystal formation occurs? which disrupts wII ionc~~l memtnxnes, and necrosis results. Certain problems~ such as those‘ nrc~l11 above, are also evident in the process of rewarming tissue. The following animal work, conducted by the I)egartment of Oral Surgety, at. t,he State University of Iowa, is to be considered as a.tl initial piloi st Nell k’our i5-lllllllit-l-cll~l and ha,s served IYor additional unreported investigation. puppies from the same litter were used, and the I’ollowing opcaratiolls wer’~ lxml~,letetl

:

I. Autogenous transplants. 2. Ilomologous transplants. 2. I;:stract,ion of the toot.h, elimination of pulp tissue, and replantat.ion of the toot.h. 1. Thr extracted tooth was esposed to glycerol, frozen in dry ice. r(‘warmed, and transplanted. 5. Extracted teeth were directly transplanted.

.frozt*n in dry ice. rc\varmctl. ;I11(1

Fig. I.--A developing tooth placed in saline and stored at 5.5” C. for two months, wmowi C0nsidera.1~1~~ and rewarmed in saline at 4Z0 C.. and then Axed in 10 per cent Formalin. acetolysis of the pulp is evident.

When the teeth were replaced, they were splinted with 0.018~gauge fracture wire (Fig. 2) and further support.ed with a hard-sett,ing surgic~al cement (Fig. 3). The puppies were maintained on :I soft mush diet wit.h w inforcements of vitamin C, methionine, and laetum.

42

D. E. WAITE

FIg. Z.-Photograph

Fig. 3.-Photograph

of splinted

showing

surgical

transplant

using O.Ol&gauge

wire.

cement pack in place over transplant.

Pig.

Fig.

Fig. 6.-Postoperative

photograph

of nutngeno~n

twnnplants.

44

D. E. WAITE

Fig. 7.

Fig. 8. Fig. 7.- -Preoperative radiograph of tooth (see Fig. 8 ). Fig. 8.- -Postoperative radiograph. Tooth removed, pulp reins lerted for flfteen days.

contents

I

an

tot

ANIMAL

The conclusions

STUDIES

ON DENTAL

TRANSPLASTS

made a.sa result of this work are as follows :

1. Freezing techniques for tooth stora.ge purposes should not be rulerI out, bat. they do require further investigation. 2. Glycerol did not stand up to our expectations, but it was c+lent that extracting water from the pulp prior to freezing was helpful. 3. The complete removal of the pulp has possibilities (Fig. 4) and. if successful, would alleviate t.he problem of pulp preservation in all. prospectirr: transplants. Fig. 9.

Fig. 10. Fig. 9.-Preoperative Fig. IO.-Postoperative

radiograph of tooth to be used for autogenous transplant. radiograph of autogenoim transplant (six week).

i T?i,r 4. Immediate autogenous transplants show good pulp preservation 5) and are well tolerated by the host (Fig. 6). 5. Root resorption on some of the transplants was noted (Figs. 7, 8, 9: sncl 10). However, this was partially due to the difficulty in immobilizing the dog’s tooth and keeping the animal from injuring it. Resorption is also believed to be due to the formation of granulation tissue? which was on the basis of in. fection.