Dentistry – Medical Aspects
Dr. Michael Tal
Dental and Medical Schools, Hebrew University – Hadassah, Jerusalem
A brief examination of some current issues in dentistry will allow us to explore their medical and scientific background, as well as some of the ethical problems which they entail. The subjects with which we shall deal are dental implants, esthetics in dentistry, orthodontics and dental care on Shabbat.
1. Dental Implants
An implant is basically an artificial root which is inserted into the jawbone and functions similarly to a tooth. The portion of the implant which protrudes into the oral cavity can be connected to various coverings which facilitate different types of rehabilitation for missing teeth.
There are four main types of implants: Transosseous, subperiostal, Blade Vent, and Branemark.
The most widely known type is the mandibular staple bone plate, an implant into the bone comprised of four screw-like pins attached to a strip of metal. The pins are placed in the oral cavity through external, surgical access (usually one-day admission) by means of an incision in the bottom of
the lower jawbone. The strip of metal is attached to the jawbone and the pins protrude through the bone into the oral cavity. These pins generally anchor a lower denture.
Transosseous implant in the lower jaw (mandible). Note the massive absorbtion of the jaw's bone mass.
This type of implant is most suitable for a lower jaw which is missing teeth where there is no other means of rehabilitation, usually since some of the bone is missing.
An operation is performed during which the soft tissue is lifted and the implant is inserted under it, resting on the ridge of the jaw. The connective tissue envelopes the implant and supports it. There is no penetration of the implant into the bone. This type of implant can be carried out in the upper or lower jaw in cases where the bone structure will not allow a implant into the bone.
Subperiostal implant in the lower jaw
The two types of implants mentioned above are relatively older methods. Owing to the necessity of general anesthesia and the clinical results, a recommendation was passed at the NIH Consensus Conference of 1988 (following long-term follow-up studies) that their use should be limited to extreme cases of disintegration of the lower jawbone, when an implant into the bone is impossible.
Blade Vent Implant
Different patterns of single implants
A blade-shaped implant into the bone, about 1-2 mm thick, with openings of different sizes facilitating growth of the bone tissue into the blade implant for anchorage. The blade is inserted into a specially prepared furrow in the jawbone, and a screw which protrudes into the oral cavity serves as support for a bridge.
These are the most common and widely known implants, developed by a Swedish orthoped during the mid-1960's. This is an implant into the bone, made in the shape of a round screw and allowing for increased contact area between the screw and the bone and wider distribution of strength. The implants are generally made of titanium coated with hydroxyaptice crystals or plasma in order to obtain biological attachment of bone to the implant (osseointegration).
Although dental implants have become a common feature of treatment programs, their success is debatable. Firstly, a distinction must be made between the success of the implant and its survival.
Until recent years success was measured by the survival of the implant. An implant which lasted in the mouth despite absorption of the bone, pain, mobility and infection around the implant, was regarded as successful even though it clearly did not meet with the criteria for success. The length of the follow-up period and number of cases examined should also be taken into account. The committee which dealt with these aspects recommended that the follow-up should be conducted by two unaffiliated centers, each having more than one researcher, and that no commercial link should exist between the manufacturer of the implants and the patients. It was determined that a success rate of 85% over five years and 80% over ten years should be the minimal requirement for successful rehabilitation by means of implants. It is only during the last five or six years that surveys have been conducted according to accepted criteria, and this – together with technical and biological
progress – is showing promising results.
Crowns (bridge) reconstruction of the missing teeth in the lower jaw. The black line along the jaw represents the nerve within the bony canal.
A survey was conducted by the Clinical Research Association in December 1992 based on the responses of 7,232 dentists. The dentists were asked to answer the following questions. Their responses – in percentages – are in parentheses:
1. To date, would you rate dental implants as
a. acceptable treatment (47%)
b. acceptable only to a certain degree with reservations (46%)
c. still within the limits of experimental treatment (7%)
d. definitely experimental treatment (2%)
2. At this time would you agree to dental implants for yourself?
a. Without any doubt (53%)
b. As a last alternative (44%)
c. I wouldn't agree at all (4%)
3. What is the success rate (over time) for implants as viewed and reported by dentists themselves?
a. Less than one year (12%)
b. 1 – 2 years (27%)
c. 3 – 5 years (43%)
d. 6 – 10 years (12%)
e. Longer than 10 years (6%)
Reconstruction of the upper jaw (maxilla) with 6 implants
From all of the above we see that implant treatment has become common despite the lack of thorough and comprehensive research which
would recommend this or other methods and would point out exactly when and under which circumstances implants are indicated.
With the full length of the bridge
2. Orthodontic Treatment
a. For esthetic purposes
b. For functional purposes
When dealing with a case where teeth are straightened without any indication of a functional disorder and the treatment is carried out for solely esthetic purposes, the question is: who initiates the treatment, the child or the parents? It is quite possible that the parents see a present need for esthetic correction of which the child is still unaware. Sometimes the request comes from the child since the problem is already disturbing him. The question is intensified by the fact that what appears at present to be a problem involving only esthetics may have functional and perhaps even psychological ramifications in the future.
In cases where orthodontic treatment is for functional purposes the child often does not perceive the problem, and may refuse. Any delay in commencing treatment will have a negative effect on necessary treatment in the future because there is a period which is critical for growth and development. If treatment is delayed, some factors become permanent or are extremely difficult to correct afterwards.
3. Esthetics in Dental Treatment
As mentioned above, it is sometimes possible to replace a missing tooth with a "Maryland bridge," which provides a good esthetic and functional solution without the need for a regular bridge or implant.
Today it is possible to overcome the esthetic problem of a single tooth which is black or darkened owing to root canal treatment, or a number teeth which have turned a dark gray-yellow following tetracycline therapy by coating the tooth with a thin layer of porcelain.
The esthetic requirements for dental treatment are constantly increasing. A popular approach in the United States holds that esthetics in dentistry is like esthetics or cosmetics in other areas. Just as a person may wish to color his hair, there is no reason why he or she should not receive dental treatment that will improve his or her appearance. What is significant about this approach is that it allows for esthetic treatment even if there is no functional need. The psychological need for an improved appearance and self-confidence is sufficient justification for treatment.
One of the problems which has arisen in the United States in recent years is the replacement of amalgam fillings (the silver-colored fillings made of an alloy of mercury fulminate with silver powder) with white fillings made of a composite material. The problems associated with the replacement are both esthetic and health-related. Some used to claim that the amalgam fillings were poisonous because they release mercury-fulminate gas, which is then absorbed into the body. It has been conclusively proven that this is false. The National Institute for Health unequivocally declared:
1. There is no conclusive proof that amalgam fillings are in any way harmful;
2. There is no reason to believe that avoiding amalgam fillings, or replacing them with composite fillings, presents any advantage to health.
Hence from an ethical point of view a dentist is not allowed to promote white fillings on the basis that they are healthier and less harmful than amalgam.
4. Dental Treatment on Shabbat
a. Damage to Front Teeth
When a front tooth is entirely dislodged (avulsion) as a result of being struck (more common in children), it is important to find the tooth and rinse it in a physiological water solution (or, when this is not possible, simply in tap water) and to replace it immediately in its socket with gentle pressure, such that it is positioned in the same way as the neighboring tooth. The dentist can then affix it to neighboring teeth using a composite material in order to stop the tooth from shifting and to ensure its re-entry into the jawbone. Antibiotics are then prescribed for about a week.
If the tooth cannot be replaced immediately, it should be placed in a cup of milk or retained in the mouth where it is surrounded by saliva and the patient should be taken immediately to a dentist, who will replace the tooth in a fixture. The main factor determining the prognosis for a dislodged tooth is the time elapsed between the injury and the replacement of the tooth in the mouth. The shorter the wait, the better the chances of success. Up until two hours the chances are usually good; beyond that the success rate falls sharply. There is no known survey which has researched the success rate as a function of the delay between injury and replacement.
Any infection in the tooth or periodontium characterized by swelling or fever is dangerous. The principal danger is that infection will spread to areas anatomically connected with the mouth, e.g. the cavernous sinus. There is also danger that infection will spread to the throat and the chest cavity, which may lead to difficulty in breathing.
c. Treatment for Sharp Pain Originating in the Pulp
An infection of the nerve inside the tooth (pulpitis), which occurs in an enclosed area, causes unbearably sharp pain. In general, apart from the pain there is no danger of the infection spreading. Such sharp pain, however, may influence other bodily systems. For instance, if the patient suffers from a heart ailment, diabetes, problems with kidneys or liver, or is receiving psychological counseling, pulpitis causes stress and may intensify existing health problems. It should also be mentioned that the first sign of a heart attack is sometimes sharp pain in the jawbone. This possibility should be ruled out before a diagnosis is made. The question is, what should be done in such cases on Shabbat?
Although no mortal danger is posed by the toothache itself, it should be taken into account that the patient possibly suffers from one of the systemic disorders mentioned above, and toothache may intensify the problem.