Method and apparatus for preserving and reimplanting a tooth

A method and apparatus are disclosed for saving an exarticulated tooth. The tooth is grasped by its crown, so as not to harm the periodontal membrane. The tooth is then placed in a net which is attached to a basket. The net and basket are immersed in a modified saline solution which preserves the cells of the periodontal membrane. The solution is held in a container which accommodates the net and basket. The lid of the container has a sponge attached to its interior surface. The container is closed, and the tooth and patient are taken to a dentist. The dentist removes the container lid, and lays the lid on a table or other surface, so that the sponge faces upward. The dentist then lifts the basket, with the tooth, out of the solution, and inverts the net so that the tooth falls out onto the sponge. The dentist grasps the tooth with a forceps and reimplants it in the patient's mouth.

BACKGROUND OF THE INVENTION 
This invention discloses a method and related apparatus for saving a tooth 
which has been exarticulated, or knocked out. 
Exarticulation of a tooth, also known as an avulsion, occurs when the 
entire tooth is forcefully and completely knocked out of its socket. Tooth 
exarticulation is quite common, especially among children. Exarticulation 
can result from falls, violence, or other causes. It is possible to save 
an exarticulated tooth, but only if the proper procedures are followed. 
Due to public ignorance, these procedures are seldom followed. When the 
exarticulated tooth is brought to a dentist, it is often too late to save 
the tooth. 
All teeth have two main components, namely the crown and the root. The 
crown is the portion of the tooth that protrudes from the gum, and is 
normally the only visible part of the tooth. The root is the portion of 
the tooth embedded in the gum. The entire tooth root is surrounded by the 
periodontal membrane, also known as the periodontal ligament. The 
periodontal membrane is a soft, ligamentous material which connects the 
tooth to its bony socket. The periodontal membrane surrounds the entire 
root, but does not extend onto the crown. 
If the periodontal membrane of an exarticulated tooth has not been 
substantially damaged, and if its cells are still alive, the tooth can be 
successfully reimplanted in its socket. After several days, the tooth will 
become naturally reaffixed to the socket. But if the cells of the membrane 
have died, the tooth is lost. 
It has been known that, if an exarticulated tooth is stored in a proper 
medium, its periodontal membrane can be preserved, and the tooth can be 
saved. Various experiments have been done to determine which media are 
best for storing an exarticulated tooth. One article describing such 
experiments is "Milk and Saliva as Possible Storage Media for 
Traumatically Exarticulated Teeth Prior to Replantation", by L. Blomlof, 
Swedish Dental Journal, vol. 5, Supp. No. 8, pages 1-26 (1981). As 
indicated by the title, the article describes experiments which tested the 
effectiveness of milk and saliva as storage media for exarticulated monkey 
teeth. Both of these naturally-occurring media were found to be effective 
in promoting the vitality of the cells of the periodontal membrane. 
The above-cited article also reports the results of experiments with 
artificial storage media. The medium that performed best in most of the 
experiments is the solution known as "Eagle's medium". Eagle's medium was 
first described in the article by M. Eagle, entitled "Amino acid 
metabolism in mammalian cell cultures", in Science, vol. 130, pages 
432-437 (1959). Eagle's medium has been modified by others, and is 
available commercially from various sources. 
The other artificial medium which has been shown effective in preserving an 
exarticulated tooth is the Hanks Balanced Salt Solution. This solution was 
also used successfully in the experiments reported in the above-cited 
article. 
Other experiments on the preservation of monkey teeth in Eagle's medium 
have been reported in "Periodontal and Pulpal Healing of Monkey Incisors 
Preserved in Tissue Culture Before Replantation", by J. O. Andreasen et 
al, in the International Journal of Oral Surgery, vol. 7, pages 104-112 
(1978). And the Hanks solution has been further tested, and found to be 
effective, in experiments reported in the article by L. Blomlof et al, 
entitled "Effect of Storage in Media with Different Ion Strength and 
Osmolalities on Human Periodontal Ligament Cells", in the Scandinavian 
Journal of Dental Research, vol. 89, pages 180-7 (1981). 
In theory, it is thus comparatively easy to preserve an exarticulated 
tooth, and then to reimplant it. Unfortunately, exarticulation of a tooth 
is a traumatic experience for the victim. If the victim is a child, the 
trauma can be equally severe for the parent as well. Neither parents nor 
children are usually well-informed about how to preserve a tooth in this 
kind of emergency. Very often, by the time the tooth has been carried to a 
dentist, the cells of the periodontal membrane have died, and it is too 
late to save the tooth. 
The present invention provides a simple method for saving an exarticulated 
tooth, and also provides an apparatus which is especially useful in 
practicing the method. The invention makes it possible for the general 
public to apply the above-described scientific findings for practical 
benefit. 
SUMMARY OF THE INVENTION 
According to the invention, an exarticulated tooth is picked up by its 
crown, so as not to harm the periodontal membrane. The tooth is then 
dropped into a net, the net being attached to a rigid, or semi-rigid, 
basket. The basket rests in a container of a modified saline solution 
which tends to enhance the vitality of the cells of the periodontal 
membrane. 
The lid of the container has a sponge means on its interior surface. The 
lid is screwed onto the container, and the tooth and patient are 
transported to the nearest dentist. The dentist opens the container, and 
places the lid on a working surface, so that the sponge means faces 
upward. The dentist then lifts the basket, with the net, from the 
solution, and inverts the net so that the tooth falls out onto the sponge 
means. The tooth is then gripped with a forceps, or other suitable tool, 
and reimplanted into its socket. 
The basket can be constructed of metal or plastic, and is preferably 
equipped with a pair of handles which facilitate the lifting of the basket 
out of the solution. The solution is preferably a modified saline 
solution, such as a Hanks' Balanced Salt Solution or an Eagle's medium. 
It is therefore an object to provide a method for saving an exarticulated 
tooth. 
It is another object of the invention to provide a method for storing the 
exarticulated tooth, and transporting it to a dentist. 
It is another object of the invention to provide apparatus which 
facilitates the practice of the method described above. 
It is another object to provide a basket and net structure which is 
especially adapted for use in storing and transporting an exarticulated 
tooth. 
It is another object to provide apparatus which can be used with 
commercially available media for storing and transporting exarticulated 
teeth. 
Other objects and advantages of the invention will be apparent to those 
skilled in the art, from a reading of the following brief description of 
the drawings, the detailed description of the invention, and the appended 
claims.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention provides a simple method and apparatus for saving a 
tooth that has been exarticulated, or suddenly and completely knocked out 
of the patient's mouth. 
In order to understand the invention, it is helpful to review the anatomy 
of a tooth. FIG. 4 is a diagram showing, in cross-section, the principal 
components of a single-rooted tooth. The tooth has a crown portion, 
designated generally by reference numeral 1, and a root portion, 
designated generally by reference numeral 3. The crown is the portion of 
the tooth which protrudes from the gingiva (or gum) 5. 
The crown portion has a coating of enamel 7, under which is located a layer 
of dentin 9, a tubular structure which supports the enamel and provides a 
sensory mechanism. Pulp chamber 11 contains the nerve of the tooth. The 
outer covering of the root of the tooth is known as the cementum, and is 
designated by reference numeral 13. The periodontal membrane 15, also 
known as the periodontal ligament or PDL, is disposed between the cementum 
13 and the bony socket 17 in which the tooth rests. 
The location at which the enamel 7 abuts the cementum 13 is known as the 
cemento-enamel junction, and is designated by reference numeral 18. 
Roughly speaking, the cemento-enamel junction is the portion of the tooth 
where the tooth crown meets the tooth root. 
The tooth shown in FIG. 4 is a single-rooted tooth. Other teeth, such as 
molars, have two roots, which are connected to each other. The structure 
of single-rooted and double-rooted teeth is otherwise the same as shown in 
FIG. 4. 
When a tooth is exarticulated, or knocked out, the periodontal membrane 
generally remains with the tooth. If this membrane is undamaged, it is 
possible to reimplant the tooth in its socket, and, after a few days, the 
tooth will become firmly and naturally reattached. 
The present invention includes an apparatus, illustrated in FIGS. 1-3, for 
facilitating the storage and transportation of an exarticulated tooth. The 
device comprises container 21, which can be a jar or bottle. Disposed 
within container 21 is basket 25 which rests on feet 23. Feet 23 can be 
integrally formed with the container, as shown, or they can be made part 
of the basket. The basket can be of wire mesh construction, or can be 
formed of plastic. Attached to basket 25 is net 27, which can be made of 
nylon, or other flexible material. The size of the net is such that it 
encloses a volume less than that of the container. FIG. 1 shows tooth 29 
resting within net 27. For the sake of clarity, no fluid is shown in the 
container, in FIG. 1, but it is understood that, when the container is 
used to store a tooth, the interior of the container will be filled with a 
solution which tends to promote the vitality of the cells of the 
periodontal membrane. 
Container 21 is closed off with lid 31. Mounted on the interior surface of 
lid 31 is sponge 33. The "interior surface" means the surface which is 
inside the container when the lid is attached to the container. The sponge 
helps to seal the contents of the container, although this seal need not 
be especially tight. The sponge has a more specific function, in the 
invention, as will be described below. Lid 31 is screwed onto the 
container, by threads 35. 
A pair of handles 37, more plainly visible in the exploded perspective view 
of FIG. 2, are attached to the basket 25. The handles are used to lift the 
basket from the container. The handles shown in the figures are of the 
form of generally circular rings, and are pivotably attached to the 
periphery of the basket. The rings can be folded over each other while the 
lid is screwed onto the container. FIG. 1 shows handles 37 in this fully 
folded-down position. The view of FIG. 3 shows the movement of handles 37, 
as they are being opened, so as to lift the basket. 
The method of the present invention can now be described. First, the 
exarticulated tooth is picked up from the ground. In grasping the tooth, 
it is important to touch only the crown portion (reference numeral 7 in 
FIG. 4), and not the periodontal membrane 15. 
Lid 31 of container 21 is then unscrewed. The container is filled with a 
modified saline solution, as described below. It is possible to store the 
solution separately from the container, and to pour the solution into the 
container when needed. It may be more convenient to store the solution 
permanently in the container. 
The tooth is dropped into the net, and into the solution. The container lid 
is reaffixed to the container. The container and the patient are then 
brought to a dentist as quickly as possible. The tooth remains gently 
suspended in the solution. Because the volume of the net is smaller than 
that of the basket, the tooth is unlikely to collide with the walls of the 
basket during transportation. 
When the patient arrives at the dentist's office, with the container and 
the tooth, the dentist unscrews the lid, and places it on a flat working 
surface, so that the sponge faces upward. The dentist then lifts the 
basket, by its handles, out of the container and the solution. The basket, 
with the net still attached, is then gently inverted, so that the tooth 
falls out onto the sponge. The dentist takes a tooth extraction forceps, 
as illustrated by reference numeral 30 in FIG. 5, or any other equivalent 
implement, and gently grips the tooth 32 by its crown portion so that the 
tips of the forceps extend no further than the level of the cemento-enamel 
junction, with the apex of the root facing away from the forceps. The 
dentist carries the tooth, in the forceps, to the patient, who has been 
anesthetized, and reimplants the tooth in its socket. 
FIG. 5 shows the tooth 32 being reimplanted, between teeth 33 and 34, by 
forceps 30. If the periodontal membrane has not been damaged during 
storage and transportation, it will reattach itself naturally to the 
socket in about 2-3 days, and the healing process is usually complete in 
about two weeks. 
In practice, one needs a retaining means (not shown in the drawings) for 
holding the reimplanted tooth in place. There are many well-known ways of 
retaining the tooth. One way is to attach brackets to the teeth, which 
hold the reimplanted tooth while allowing the tooth some movement. Another 
method is to use a bonding material, of the type commonly used to fill 
chipped teeth and the like, to connect the reimplanted tooth to its 
neighbors. The bonding material allows the tooth to move somewhat. After 
the healing process is complete, the bonding material can be removed. 
The only unacceptable means of retaining the reimplanted tooth is the use 
of a rigid bar which prevents any movement of the reimplanted tooth. Such 
a rigid retaining means can cause ankylosis, a condition in which the bone 
around the tooth becomes connected directly to the dentin, and the 
periodontal membrane is entirely lost. 
As stated above, two preferred solutions for use in the container are the 
so-called Hanks' Balanced Salt Solutions, and Eagle's medium. Both of 
these media are are commercially available from Gibco Laboratories, of 
Grand Island, N.Y., and from other sources. 
The Hanks solutions contain a mixture of various inorganic salts, plus 
certain other components. The salts found in several variations of the 
Hanks solutions are shown in the following table. 
______________________________________ 
Concentration in g/l 
Solution No.: 
Component: 1 2 3 4 5 
______________________________________ 
CaCl.sub.2 (anhyd.) 
0.14 0 1.40 0 0.14 
KCl 0.40 0.40 4.00 4.00 0.40 
KH.sub.2 PO.sub.4 
0.06 0.06 0.60 0.60 0.06 
MgCl.sub.2 .multidot. 6H.sub.2 O 
0.10 0 1.00 0 0 
MgSO.sub.4 (anhyd.) 
0 0 0 0 0.0977 
MgSO.sub.4 .multidot. 7H.sub.2 O 
0.10 0 1.00 0 0 
NaCl 8.00 8.00 80.00 
80.00 8.00 
NaHCO.sub.3 0.35 0.35 0 0 0 
Na.sub.2 HPO.sub.4 
0 0 0 0 0.048 
Na.sub.2 HPO.sub.4 .multidot. 7H.sub.2 O 
0.09 0.09 0.90 0.90 0 
______________________________________ 
The Hanks solutions also contain a certain amount of glucose, for purposes 
of providing nutrition for the cells stored in the solution, and may also 
contain a coloring agent. 
Solutions Nos. 3 and 4 can be characterized as more concentrated versions 
of Solutions Nos. 1 and 2. 
Eagle's medium, in its modified forms, includes inorganic salts of the 
types shown in the above table, plus vitamins, amino acids, and 
antibiotics. More specifically, the amino acids which are used in the 
Eagle's medium available from Gibco Laboratories include L-Arginine, 
L-Cystine, L-Glutamine, L-Histidine, L-Isoleucine, L-Leucine, L-Lysine, 
L-Methionine, L-Phenylalanine, L-Threonine, L-Tryptophane, L-Tryosine, and 
L-Valine. The vitamins used in the Eagle's medium sold by Gibco include 
biotin, D-Ca pantothenate, choline chloride, folic acid, I-inositol, 
nicotinamide, pyridoxal HCl, riboflavin, and thiamine HCl. In the 
experiments reported in the article by Blomlof in the Swedish Dental 
Journal, cited above, the Eagle's medium was augmented by calf serum. 
A major purpose of the Hanks solution, or Eagle's medium, or any other type 
of artificial solution used to store a tooth, is to provide a composition 
which most nearly duplicates that of the fluid in the cells being 
preserved. If the tooth is stored in a solution which does not match the 
composition of the cell contents, there will be a net inflow or outflow of 
ions across the boundary of the cell. This ion transport can destroy the 
cell. In fact, if the tooth is placed in pure water, the difference in ion 
concentration between the interior and exterior of the outer cells on the 
periodontal membrane will cause those cells to explode, thereby killing 
them. 
Because water can kill the cells of the periodontal membrane, it is not 
recommended that the tooth be rinsed with water before reimplantation. 
Moreover, the tooth will be rinsed automatically when it is stored and 
transported in one of the solutions described above. 
The Hanks solutions and Eagle's medium have been shown to be particularly 
effective in preserving the vitality of the cells of the periodontal 
membrane. Indeed, the experiments with Eagle's medium suggest that it is 
possible to store exarticulated teeth in that medium for several days 
without damage to the membrane. The Hanks solution appears to be effective 
for several hours, but it may have the advantage of having a longer shelf 
life than Eagle's medium. 
It is quite possible that other artificial solutions can be used as well. 
There are many other such solutions, which are commercially available, and 
which have been developed for use by research laboratories for the purpose 
of preservation of various natural tissues. Examples include the so-called 
Gey's Balanced Salt Solution and Puck's Saline. However, the latter 
solutions are not believed to have been tested with exarticulated teeth. 
The specific embodiment described above should be considered exemplary, and 
not limiting. The invention can be modified in many ways, within the scope 
of the disclosure. For example, the structure of the container can be 
varied, and the basket and net can assume different forms. Different types 
of sponge materials, and different types of closures for the container, 
can be employed. The basket can be made without handles, or the handles 
can be formed in other shapes. As described above, various balanced 
solutions could be used to preserve the tooth. Both the Hanks solutions 
and Eagle's medium represent entire families of solutions, and it is 
possible that other cellpreserving solutions could be substituted. These 
and other similar modification should be considered within the spirit and 
scope of the following claims.