some wisdom about the removal of wisdom teeth
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Indications for the removal of impacted third molars include
pericoronitis, periodontitis, caries, resorption of the second
molar, cyst formation, and interference with orthodontic
treatment. While the prophylactic removal of asymptomatic
third molars may still be controversial, there is a general
agreement that they should be removed when a patho-
logic condition is present. This article reviews specific
indications for removal of impacted third molars, the argu-
ments for their prophylactic removal, and the specific
instances when such teeth should not be removed.
Indications for Removal of ImpactedThird MolarsPericoronitis
Pericoronitis is the most common condition affecting
impacted third molars. Bacteria gain access into the fol-
licular space through an opening in the overlying gingiva
or through the gingival crevice distal to the second molar.
Such infections may remain localized in the pericoronal
region, spread via the lymphatic system into the sub-
mandibular lymph nodes, or extend directly into the
surrounding tissues. The most frequent site of direct exten-
sion is the buccal vestibule above the attachment of the
buccinator muscle, which causes a vestibular abscess.
Occasionally, however, the infection can spread beneath
the buccinator muscle and give rise to a buccal space
abscess or posteriorly into the pterygomandibular space.
Once there has been an episode of pericoronitis, there is
a tendency for the infection to recur intermittently when
complete eruption of the tooth is not possible.
Constant food impaction and plaque retention between a
partially impacted third molar and the adjacent second
molar can result in inflammation and considerable loss of
interseptal bone (Figure 1). Such periodontal pocket for-
mation not only weakens the support of the second molar,
which may loosen, but also apical extension of the infec-
tion that can lead to its devitalization. Once a deep perio-
dontal pocket develops, removal of the impacted third
Figure 1. Radiograph of an impacted third molarcausing severe periodontal destruction as wellas caries involving the second molar. This couldhave been prevented by earlier removal ofthe third molar.
Daniel M. Laskin, DDS, MS, DSc (Hon), received a DDS degree
from Indiana University and a Master of Science degree from
the University of Illinois. He is Professor and Chairman of the
Department of Oral and Maxillofacial Surgery, School of
Dentistry, and Professor and Chairman of the Division of Oral
and Maxillofacial Surgery, Department of Surgery, School of
Medicine, Virginia Commonwealth University.
Some Wisdom Aboutthe Removal of Wisdom Teeth
Daniel M. Laskin, DDS, MS, DSc (Hon)
September/October 2001 15
molar will not eliminate it. Therefore, the impacted tooth
should be extracted at the first sign of periodontal infec-
tion. This will not only arrest the condition, but may also
decrease the excessive crevicular depth on the distal aspect
of the second molar.1
Partial eruption of an impacted third molar in the oral envi-
ronment increases its susceptibility to caries due to the
accumulation of food debris and the difficulty of keeping
the area clean. The restoration of such carious lesions is
often impossible due to poor access. Even when the tooth
is restored, recurrent caries is a frequent finding. For these
reasons, removal of the third molar is indicated, even when
the carious lesion does not extend into the pulp.
The same factors that make the third molar suscep-
tible to caries can also affect the adjacent second molar
(Figure 1). Such lesions should not be restored until the
third molar is removed. This not only reduces the possi-
bility of recurrent tooth decay, but also avoids possible
damage to the restoration during the surgical procedure.
Pressure from the crown of an impacted third molar against
the root of the second molar may result in pathologic
resorption (Figure 2A & 2B).2 When this diagnosis is made,
care must be exercised not to confuse such areas of root
resorption with the shadows produced in the radiograph
by the overlap of the molars due to improper horizontal
angulation of the cone of the x-ray machine or the bucco-
or linguoversion of the impacted tooth (Figure 3).
Removal of only the impacted tooth is indicated if the
resorptive process has not involved the pulp of the sec-
ond molar. If the second molar has been devitalized and
must be extracted, however, it may be advisable to leave
the third molar in young patients.
The third molar is the tooth most often involved in the for-
mation of dentigerous cysts. Eighty percent of the follicles
around the crown of the third molar are wider than 2.5 mm
and have been shown to have an epithelial lining.3 Such
teeth should be removed whenever there is indication of
Wisdom About Wisdom Teeth
16 The Journal of Practical Hygiene
Figure 2A. Impacted third molar causing resorption of thedistal root of the second molar. 2B. Post-extraction radio-graph reveals the extent of the damage.
follicular enlargement. Frequent radiographic evaluation
is indicated in those instances when there is possible
enlargement of the follicle and the tooth has been allowed
to remain. A cyst can develop and remain asymptomatic
for long periods during which it may grow to a large size
and cause considerable bone destruction. Moreover,
ameloblastomas and even carcinomas arising in the walls
of dentigerous cysts have been reported.4,5
Occasionally, a patient may complain of facial pain, yet
there may be no apparent clinical or radiographic evidence
of any abnormality other than the presence of a deeply
embedded, impacted third molar with no obvious oral com-
munication. Though there may be no satisfactory expla-
nation for why such a tooth can cause pain, some patients
experience relief following its removal. Therefore, it is jus-
tified to remove impacted third molars in such instances.
Presence in an Edentulous Ridge
An impacted tooth is occasionally found during a routine
radiographic examination in a ridge that appears to be
edentulous. Unless the tooth is completely covered with
bone and its extraction would cause considerable destruc-
tion of the alveolar process, it should be removed.
Determining the amount of bone over the tooth from a
radiograph, however, is not always a simple task. Since
the radiograph provides merely a two-dimensional view of
the tooth, it may appear to have considerable bone over
the superior surface when actually it is only partially cov-
ered. If allowed to remain, compression of the overlying
mucosa between the crown of the tooth and a denture
may not only cause considerable pain, but the pressure can
cause an ulceration of the mucosal tissue, which can pro-
duce a pathway for the development of an infection.
In addition to the aforementioned conditions, impacted
third molars may also be involved in other situations that
require their removal. These teeth can sometimes interfere
with the normal path of eruption of the adjacent second
molar and should be removed as soon as this situation is
recognized so that the second molar has the best oppor-
tunity to erupt. Likewise, impacted third molars can inter-
fere with distal orthodontic tooth movement. They can also
interfere with the proper performance of orthognathic
surgery when this involves the third molar region. In such
cases, the impacted tooth must be removed at the time of
surgery or, preferably, prior to it.
Benign and malignant neoplasms of the soft tissues and
bone can occur in the third molar region, and the third
September/October 2001 17
Figure 3. Impacted third molar in linguoversion appearingto be causing resorption of the second molar.
molar should never be allowed to remain when its reten-
tion would jeopardize the successful removal of the lesion.
Moreover, an impacted third molar should never be left in
an area that will be subjected to radiation therapy.
The presence of an impacted third molar weakens the
mandible and therefore trauma to the jaw is more likely
to cause a fracture. Should a mandibular fracture occur in
the third molar region, removal of the tooth is often indi-
cated as part of the treatment (Figure 4). It may be advis-
able to consider removal of impacted teeth prophylactically
in persons who engage in contact sports.
Prophylactic Removal of ImpactedThird MolarsClinical experience has shown that most impacted teeth
will ultimately give rise to some difficulty. For example,
the incidence of pericoronitis has been reported to range
from 27% to 34%, and the incidence of caries to range
from 3% to 15% in patients presenting for removal of
Several studies have also shown a significant rela-
tionship of periodontitis and periodontal pocket formation
with impacted third molars.9,10 Moreover, an increase in the
visible plaque and gingival bleeding indices as far forward
as the canine teeth has been demonstrated in patients with
partially erupted third molars, and the plaque index was
found to improve after their removal.11-13 With the recent
implication of chronic periodontal infection as a possible
contributor to cardiovascular disease,14 this may also be
an important justification for the prophylactic removal of
impacted teeth. Additionally, removal of these teeth at an
early age (before 25 years) has been shown to result in a
significant postoperative reduction in the depth of the infra-
bony defects, whereas this does not occur in older patients.15
The National Institute of Dental Research Consensus
Development Conference on Removal of Third Molars
recommends that such teeth be removed as soon as it is
obvious that there is insufficient space to accommodate
them or that they are not in a position for normal erup-
tion to occur.16 This conference concluded that impaction
or malposition of a third molar may justify its removal, and
that such treatment is not considered prophylactic. Growth
of the mandible, with the accompanying resorption of the
anterior border of the ramus to provide space for the third
molar as well as growth of the maxilla are essentially
completed between 16 and 17 years of age, and therefore
the decision regarding prophylactic removal can generally
be made at about that time.
Although their potential for causing crowding of the
mandibular incisors is frequently given as a reason for
the prophylactic removal of impacted third molars, and
this is sometimes seen as these teeth are erupting, the rela-
tionship between these two events remains unproven.17,18
If an anterior force was caused by the erupting third
molars, it would require a corresponding forward shift of
all of the posterior teeth in order for it to be transmitted
to the incisors, and this does not occur. Moreover, under
such circumstances, the disruption of tooth contact would
be expected to occur in the canine and not the incisor
region. An alternative explanation for the development of
anterior tooth crowding may be the increased plasticity of
the alveolar bone and periodontal ligaments that accom-
panies the hormonal changes in adolescence, which causes
an imbalance between the forces ordinarily contributing to
tooth stability.18 Supporting this concept is the fact that
incisor crowding is also evident in persons with missing
third molars and in those who have had them removed
prior to orthodontic treatment.16,17 In the latter instance, the
crowding may represent the relapse of teeth orthodonti-
cally placed in a physiologically untenable position. Other
possible factors contributing to crowding of the lower
incisors are a restriction of forward mandibular growth
Wisdom About Wisdom Teeth
18 The Journal of Practical Hygiene
Figure 4. Mandibular fracture in the third molar region. Figure 5. Radiograph of an impacted third molar in apatient in whom the second molar is at risk due to adeep restoration.
by a deep maxillary overbite and the natural tendency of
these teeth to upright with age.
Contraindications Since the surgical procedure in an adult is generally more
complex,19 it is best to allow deeply embedded, asympto-
matic impacted third molars that are covered with bone and
do not communicate with the oral cavity to remain, even
though there is a possibility that pathologic involvement
may subsequently occur. If one is dealing with serious
pathology, it is generally possible to adopt a temporiz-
ing approach in a patient who is a poor surgical risk.
Pericoronal and/or periodontal infections can be treated
with irrigation and antibiotics, caries can be excavated and
a restoration placed, a pulp can be devitalized, a cyst can
be marsupialized and, if necessary, a second molar can be
extracted to create space in the dental arch. It should be
emphasized, however, that such procedures are compro-
mises and not the usual treatments of choice.
An impacted third molar should not be removed when
there is some question about the future status of the
second molar (eg, deep caries, large restoration, endodon-
tic treatment, or extensive periodontal disease) (Figure 5).
In such cases, it is assumed that if the second molar is
extracted at a subsequent time, the third molar will either
erupt into a more functional position or can at least serve
as a bridge abutment. The position of the impacted tooth
and the age of the patient are important considerations
in making this assumption.
ConclusionImpacted third molars are subject to a variety of pathologic
processes, some of which may result in serious irreversible
conditions. Therefore, it is important to carefully examine
these teeth at every dental visit. The dental hygienist plays
an important role in this process. When such teeth are pre-
sent, the advantages and disadvantages of prophylactic
removal need to be discussed with the patient so that
an informed decision about their retention or removal can
References1. Szmyd L, Hester WR. Crevicular depth of the second molar in impacted
third molar surgery. J Oral Surg 1963;21:185-189.
2. Nitzan D, Keren T, Marmary Y. Does an impacted tooth cause rootresorption of the adjacent one? Oral Surg Oral Med Oral Pathol1981;51(3):221-224.
3. Conklin WW, Stafne EC. A study of odontogenic epithelium in thedental follicle. J Amer Dent Assoc 1949;39:143-148.
4. Shteyer A, Lustmann J, Lewin-Epstein J. The mural ameloblastoma:A review of the literature. J Oral Surg 1978;36(11):866-872.
5. Maxymiw WG, Rood RE. Carcinoma arising in a dentigerous cyst: Acase report and review of the literature. J Oral Maxillofac Surg 1991;49(6):639-643.
6. Nordenram A, Hultin M, Kjellman O, Ramstrom G. Indications forsurgical removal of the mandibular third molar: Study of 2,630 cases.Swed Dent J 1987;11(1-2):23-29.
7. Lysell L, Rohlin M. A study of indications used for removal of themandibular third molar. Int J Oral Maxillofac Surg 1988;17(3):161-164.
8. Stanley HR, Alatter M, Collett WK, et al. Pathological sequelae of“neglected” impacted third molars. J Oral Pathol 1988;17(3):113-117.
9. Ash MM Jr, Costich ER, Hayward JR. A study of periodontal hazardsof third molars. J Periodontal 1962;33:209-219.
10. von Wowern N, Nielsen HO. The fate of impacted lower third molarsafter the age of 20. A four-year clinical follow-up. Int J Oral MaxillofacSurg 1989;18(5):277-280.
11. Ylipaavalniemi P, Turtola L, Rytomaa I, et al. Effect of position ofwisdom teeth on the visible plaque index and gingival bleeding index.Proc Finn Dent Soc 1982;78(1):47-49.
12. Giglio JA, Gunsolley JC, Laskin DM, Short KJ. Effect of removing thirdmolars on plaque and gingival indices. J Oral Maxillofac Surg 1994;52(6):584-587.
13. Grondahl HG, Lekholm U. Influence of mandibular third molars onrelated supporting tissues. Int J Oral Surg 1973;2(4):137-142.
14. Beck JD, Pankow J, Tyroler HA, Offenbacher S. Dental infectionsand atherosclerosis. Am Heart J 1999;138:528-533.
15. Kugelberg CF, Ahlstrom U, Ericson S, Hugoson A. Periodontal heal-ing after impacted lower third molar surgery. A retrospective study.Int J Oral Surg 1985;14(1):29-40.
16. NIH consensus development conference on removal for third molars.J Oral Surg 1980;38(3):235-236.
17. Bjork A, Skieller V. Normal and abnormal growth of the mandible. Asynthesis of longitudinal cephalometric implant studies over a periodof 25 years. Eur J Orthodont 1983;5(1):1-46.
18. Ades AG, Joondeph DR, Little RM, Chapko MK. A long-term study ofthe relationship of third molars to changes in the mandibular dentalarch. Am J Orthodont Dentofac Orthop 1990;97(4):323-335.
19. Osborn TP, Frederickson G, Small IA, Torgeson TS. A prospectivestudy of complications related to mandibular third molar surgery.J Oral Maxillofac Surg 1985;43(10):767-769.
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20 The Journal of Practical Hygiene
1. A partially impacted mandibular third molarcan cause loss of the interseptal bone betweenit and the second molar due to:A. Pressure on the bone.B. Movement of the second molar. C. A failure to support the bone.D. Constant food impaction.
2. Which of the following occurs followingremoval of an impacted third molar?A. It can result in regeneration of the interseptal bone
distal to the second molar.B. It can result in decreased crevicular depth distal to
the second molar.C. It can prevent further periodontal disease distal to
the second molar.D. All of the above.
3. Restoration of carious lesions in third molars isseldom done because of:A. The difficult access to the lesion.B. The cost of such restorations.C. The close proximity of the dental pulp in such teeth.D. The weakness of the enamel makes restoration
4. A follicular space around the crown of anunerupted third molar greater than 2.5 mmwide is generally considered to be:A. Within the range of normality.B. A dentigerous cyst.C. An early ameloblastoma.D. An eruption cyst.
5. With regard to periodontitis and periodontalpocket formation, removal of impactedmandibular third molars causes decreased:A. Gingivitis in the maxillary teeth.B. Plaque and bleeding indices in the anterior teeth.C. Periodontal pocket formation in the molar and
premolar teeth.D. Plaque and bleeding indices in the posterior teeth.
6. Which of the following statements regardingradiographs of impacted third molars is false:A. There may be only partial bony coverage of the
superior surface even when there appears to befull coverage.
B. Radiographs are helpful in determining the amountof bone over the tooth.
C. Radiographs are not helpful in determining whetherthere is buccal or lingual bone over the crown.
D. A radiograph may show bone over the crowneven when no bone is present.
7. Which of the following is usually not a contraindi-cation to the removal of impacted third molars:A. A deeply embedded, asymptomatic third molar in
an adult.B. The poor systemic condition of the patient.C. The potential risk of having to extract the second
molar at a future time.D. The lack of radiographic pathosis in a patient with
chronic facial pain.
8. Which of the following is not a reason for removingimpacted third molars in orthodontic patients?A. They can interfere with orthodontic tooth movement.B. They can interfere with orthognathic surgery.C. They can cause crowding of the lower incisors.D. They can impede eruptions of the second molar.
9. The most common pathologic condition involvingimpacted third molars is:A. Dental caries.B. Periodontitis.C. Pericoronitis.D. Cyst formation.
10. The most frequent site for the spread of a periocoronal infection is the:A. Submandibular space.B. Buccal vestibule.C. Pterygomandibular space.D. Buccal space.
To submit your CE Exercise answers, please use the answer sheet found within the CE Editorial Section of this issue and complete it
as follows: 1) Identify the Article; 2) Place an X in the appropriate box for each question; 3) Clip the answer sheet from the page and
mail it to the CE Department at Montage Media Corporation. For further instructions, please refer to the CE Editorial Section.
Answers to the 10 multiple-choice questions for this CE exercise are based on the article “Some Wisdom About the Removal of
Wisdom Teeth” by Daniel M. Laskin, DDS, MS, DSc (Hon).
WARNING: The Journal of Practical Hygiene encourages its readers to pursue further education when necessary
before implementing any new procedures expressed in this article. Reading an article in The Journal of Practical
Hygiene does not fully qualify you to incorporate these new techniques or procedures into your practice.
Learning Outcomes:• Review specific indications for removal of impacted third molars.
• Understand the arguments for their prophylactic removal.
• Identify specific instances when such teeth should not be removed.
CONTINUING EDUCATION (CE) EXERCISE NO. 5 CECONTINUING EDUCATION