LETTER
TO THE
EDITOR
More on third molar enucleation To the Editor: This JOURNAL considerable
is
in
regard
entitled inquiry
to
the
“Reservations into this
letter on topic,
from Third your
Chester
S.
Molar readers
Enucleation.” may be
Handleman As interested
in
the we
January,
have in our
1976,
undertaken findings,
in
the
same format used by Dr. Handleman. Assumption One. The Accuracy of Computer Prediction: Our research showed that third molar space, measured from the center of the ramus to the second molar, is an important indicator of likelihood of eruption. This likelihood varies from 90 per cent chance of impaction at 20 mm. of space to 90 per cent chance of eruption at 30 mm. of space. This space can be predicted by the computer within i: 2.8 mm. at the age of 8 years.
We may combine these figures to provide the public with an answer to the question “What are my chances, Doctor?” Today there are two schools of thought on third molar enucleation-wait until they cause problems (and about one-half become impacted] or extract them all prophylactically. Knowing the patient’s chances in advance permits a more individual approach to diagnosis. It is up to the clinician and the patient to decide what probability is sufficient to warrant enucleation. The computer also gives a range of probabilities and the limits of how orthodontics might affect the decision. If the patient is a candidate for orthodontic treatment, and if the probabilities show that this could affect the decision, the case should be referred to an orthodontist for a complete diagnostic work-up according to the various predictive techniques now available’ As a rule of thumb, each millimeter of forward or backward movement of the lower first molar due to treatment changes the chance of impaction 10 per cent. Assumption Two. All Impacted Third Molars Must Be Removed: This is another area which requires judgment and on which are published a variety of opinions. There is a considerable body of opinion in favor of the removal of all impacted teeth. In 1961, Dachi and Howell2 reported that in their study of 3,874 full-mouth radiographs, 37 per cent of mandibular and 15 per cent of maxillary impacted third molars were found to have areas of radiolucency around their crowns. In addition, removal of impacted teeth is far more difficult in later life and is noted to involve fractures of the jaw and damage to the adjacent teeth in some patients. Assumption Three. The ProbabGty of Loss of First or Second Molars Due to Caries or Traumatic Injuries: Anderson and associates3 have shown that the loss of first or second molars has been approximately 10 per cent in the upper socioeconomic groups. While loss in the lower socioeconomic groups was higher, this seems to be due more to reluctance to apply restorative procedures than to the rate of infection. Children who are candidates for third molar enucleation are already involved in a comprehensive program of dental care. They would not be likely to have as great a frequency of loss as their forebears, especially if they have been made aware that they will have fewer teeth and should take the utmost care to preserve their first and second
692
Letter
to editor
693
molars. The increased use of endodontic techniques has also helped to preserve posterior teeth which otherwise would have been extracted in the past. Also, in order for the third molar to be useful as a replacement for the first or second molar, the loss of the first or second molar must occur prior to removal of the impacted tooth. While the numbers are not available at this time, a further look will probably find relatively few persons who actually profit from use of the third molar in this way without extensive orthodontic treatment. Assumption Four. The Eruption of Mandibular Third Molars Is a Potential Cause of Crowding of the lower Incisor: Vego4 showed a significantly greater loss in arch perimeter between the ages of 14 and 20 years in untreated dentitions with erupting third molars than in persons with third molar agenesis. Kaplan5 showed 50 per cent greater postretention crowding in treated cases with erupting third molars but, because of his smaller sample size, this was deemed not statistically significant. less mesial migration of the first molars in patients with dence molar
indicated eruption.
that
between
half
and
two
thirds
Schwartz6 third molars
of postpubertal
showed significantly enucleated. The evi-
crowding
is due
to third
Assumption five. The Enucleation of Third Molar Buds Is a Simple Atraumatic Procedure: Thousands of third molar enucleations have been performed, and in the vast majority of cases the swelling is gone by the second day and the patient can go back to school almost immediately. This is because at the early stage of development of the third molar, the crypt is accessible by an incision in the gingiva and excessive removal of bone is thereby avoided. However, the technique must be specially learned, and not many oral surgeons are practiced in the method. Timing is also important. After the crown calcifies, removal will be quite difficult because of the problem of the crown rotating in its crypt. Another area of concern to the public is one of economics. Mandibular third molars can be enucleated at perhaps one fourth the cost of removal of impactions in later life. We believe that the concept of early third molar enucleation, when indicated by prediction, can be a valuable service worthy of consideration by the specialty. At least, prediction cleation.
now allows the weighing Perhaps the existence
of the likelihood of such quantitative
public
image
the
at
a time
when
public
image
of future techniques of
medicine
events with in dentistry in
general
and without enuwill increase its is sinking.
J. Chaconas, D.D.S., M.S. UCLA School of Dentistry Los Angeles, California 90024 Xpiro
REFERENCES
1. Schulhof, R. J., and Bagha, L.: A statistical evaluation of the Ricketts and Johnston growth forecasting methods, AM.J.ORTHOD. 67: 25%276,1975. 2. Dachi, 5. F., and Howell, F. V.: Oral Surg. 14: 11651169, 1961. 3. Anderson, Donald, Thompson, Gordon N., and Popovich, Frank: J. Pub. Health Dent. 34: Spring issue, 1974. 4. Vego, LeRoy : A longitudinal study of mandibular arch perimeter, Angle Orthod. 32: 187. 192, 1962. 5. Kaplan, Ross G.: Mandibular third molars and postretention crowding, AM. J. ORTHOD. 66: 411-429, 1974. 6. Schwartz, Claus W.: The influence of third molar germectomy; Eur. Orthod. Sot., pp. 551. 562, 1975.
TO THE
EDITOR
More on third molar enucleation To the Editor: This JOURNAL considerable
is
in
regard
entitled inquiry
to
the
“Reservations into this
letter on topic,
from Third your
Chester
S.
Molar readers
Enucleation.” may be
Handleman As interested
in
the we
January,
have in our
1976,
undertaken findings,
in
the
same format used by Dr. Handleman. Assumption One. The Accuracy of Computer Prediction: Our research showed that third molar space, measured from the center of the ramus to the second molar, is an important indicator of likelihood of eruption. This likelihood varies from 90 per cent chance of impaction at 20 mm. of space to 90 per cent chance of eruption at 30 mm. of space. This space can be predicted by the computer within i: 2.8 mm. at the age of 8 years.
We may combine these figures to provide the public with an answer to the question “What are my chances, Doctor?” Today there are two schools of thought on third molar enucleation-wait until they cause problems (and about one-half become impacted] or extract them all prophylactically. Knowing the patient’s chances in advance permits a more individual approach to diagnosis. It is up to the clinician and the patient to decide what probability is sufficient to warrant enucleation. The computer also gives a range of probabilities and the limits of how orthodontics might affect the decision. If the patient is a candidate for orthodontic treatment, and if the probabilities show that this could affect the decision, the case should be referred to an orthodontist for a complete diagnostic work-up according to the various predictive techniques now available’ As a rule of thumb, each millimeter of forward or backward movement of the lower first molar due to treatment changes the chance of impaction 10 per cent. Assumption Two. All Impacted Third Molars Must Be Removed: This is another area which requires judgment and on which are published a variety of opinions. There is a considerable body of opinion in favor of the removal of all impacted teeth. In 1961, Dachi and Howell2 reported that in their study of 3,874 full-mouth radiographs, 37 per cent of mandibular and 15 per cent of maxillary impacted third molars were found to have areas of radiolucency around their crowns. In addition, removal of impacted teeth is far more difficult in later life and is noted to involve fractures of the jaw and damage to the adjacent teeth in some patients. Assumption Three. The ProbabGty of Loss of First or Second Molars Due to Caries or Traumatic Injuries: Anderson and associates3 have shown that the loss of first or second molars has been approximately 10 per cent in the upper socioeconomic groups. While loss in the lower socioeconomic groups was higher, this seems to be due more to reluctance to apply restorative procedures than to the rate of infection. Children who are candidates for third molar enucleation are already involved in a comprehensive program of dental care. They would not be likely to have as great a frequency of loss as their forebears, especially if they have been made aware that they will have fewer teeth and should take the utmost care to preserve their first and second
692
Letter
to editor
693
molars. The increased use of endodontic techniques has also helped to preserve posterior teeth which otherwise would have been extracted in the past. Also, in order for the third molar to be useful as a replacement for the first or second molar, the loss of the first or second molar must occur prior to removal of the impacted tooth. While the numbers are not available at this time, a further look will probably find relatively few persons who actually profit from use of the third molar in this way without extensive orthodontic treatment. Assumption Four. The Eruption of Mandibular Third Molars Is a Potential Cause of Crowding of the lower Incisor: Vego4 showed a significantly greater loss in arch perimeter between the ages of 14 and 20 years in untreated dentitions with erupting third molars than in persons with third molar agenesis. Kaplan5 showed 50 per cent greater postretention crowding in treated cases with erupting third molars but, because of his smaller sample size, this was deemed not statistically significant. less mesial migration of the first molars in patients with dence molar
indicated eruption.
that
between
half
and
two
thirds
Schwartz6 third molars
of postpubertal
showed significantly enucleated. The evi-
crowding
is due
to third
Assumption five. The Enucleation of Third Molar Buds Is a Simple Atraumatic Procedure: Thousands of third molar enucleations have been performed, and in the vast majority of cases the swelling is gone by the second day and the patient can go back to school almost immediately. This is because at the early stage of development of the third molar, the crypt is accessible by an incision in the gingiva and excessive removal of bone is thereby avoided. However, the technique must be specially learned, and not many oral surgeons are practiced in the method. Timing is also important. After the crown calcifies, removal will be quite difficult because of the problem of the crown rotating in its crypt. Another area of concern to the public is one of economics. Mandibular third molars can be enucleated at perhaps one fourth the cost of removal of impactions in later life. We believe that the concept of early third molar enucleation, when indicated by prediction, can be a valuable service worthy of consideration by the specialty. At least, prediction cleation.
now allows the weighing Perhaps the existence
of the likelihood of such quantitative
public
image
the
at
a time
when
public
image
of future techniques of
medicine
events with in dentistry in
general
and without enuwill increase its is sinking.
J. Chaconas, D.D.S., M.S. UCLA School of Dentistry Los Angeles, California 90024 Xpiro
REFERENCES
1. Schulhof, R. J., and Bagha, L.: A statistical evaluation of the Ricketts and Johnston growth forecasting methods, AM.J.ORTHOD. 67: 25%276,1975. 2. Dachi, 5. F., and Howell, F. V.: Oral Surg. 14: 11651169, 1961. 3. Anderson, Donald, Thompson, Gordon N., and Popovich, Frank: J. Pub. Health Dent. 34: Spring issue, 1974. 4. Vego, LeRoy : A longitudinal study of mandibular arch perimeter, Angle Orthod. 32: 187. 192, 1962. 5. Kaplan, Ross G.: Mandibular third molars and postretention crowding, AM. J. ORTHOD. 66: 411-429, 1974. 6. Schwartz, Claus W.: The influence of third molar germectomy; Eur. Orthod. Sot., pp. 551. 562, 1975.
