Category Archives: Principles of Management of Impacted Teeth

Summary

Summary 

The three classification systems discussed so far are used in conjunction to determine the difficulty of an extraction. For example, a mesioangular impaction with a class 1 ramus and a class A depth is easy to remove and is
essentially the extraction of an erupted tooth (Fig. 9-26): . However, as the ramus relationship changes to a class 2 and the depth of the impaction increases to a class B, the degree of difficulty becomes greater. A horizontal
impaction with a class 2 ramus relationship and a class B depth is a moderately difficult extraction and one that most general practitioners do not” want to attempt (Fig. 9-27). Finally, the most difficult of all impactions is a distoangular impaction with a class 3 ramus relationship at a class C depth. Even specialists view removing this tooth as a surgical challenge (Fig. 9-28). FIG. 9-24

FIG. 9-24

FIG. 9-24 Pell and Gregory class B’ impaction. Occlusal plane of impacted tooth is between occlusal plane and cervical line of second molar.
FIG. 9-25 Pel! and Gregory class C impaction. Impacted tooth is below cervical line of second molar. FIG. 9-25

FIG. 9-25

Pel! and Gregory class C impaction. Impacted tooth is below cervical line of second molar. FIG. 9-26'

FIG. 9-26′

FIG. 9-26′ Mesioangular impaction with class 1 ramus r,elationship and class A depth. AI! three classifications make it easiest type of impaction to remove. F!c,. 9· 27

F!c,. 9· 27

Horizontal impaction with class’ 2 ramus relationship
and class B depth makes it moderately difficult to extract

FIG. 9-28

FIG. 9-28

 

Relationship to Anterior Border of Ramus

Relationship to Anterior Border of Ramus

Another method for classifying. impacted mandibular third molars is based on the amount of impacted tooth that is covered with the bone of the mandibular ramus .• This classification is known as the Pell and GregQIJ’classification and is sometimes referred to as the Pell and Gregory
classes 1, 2, and 3. For this classification it is important that till surgeon carefully examine the: relationship bctw.-c n the tooth and the anterior part of the ramus. If the mesiodistal diameter of the crown is completely anterior to the anterior border of the mandibular ramus, it is in a class- 1 relationship. If the tooth is angled in a vertical direction, the chances for the tooth to erupt into a normal position are good (Fig. 9-20). If the tooth is ‘Positioned posteriorly so that approximately one half is covered by the ramus, the tooth’s relationship with the ramus is class 2. In the class 2 situation the tooth cannot become completely free from bone, because a small shelf of bone overlies the distal portion of . the tooth (Fig. 9-21). A class 3 relationship between the tooth and ramus occurs when the tooth is located completely within the mandibular ramus (Fig. 9-22). It should be obvious that the lass 1 relationship will provide the greatest accessibility to the impacted tooth and therefore will be easiest to remove. The class 3 relationship provides the least accessibility and therefore presents the greatest difficulty.

FIG. 9-20

FIG. 9-20FIG. Q 2D Pell and Gregory class t impaction. Mandibular third

molar has sufficient anteroposterior room (i.e., anterior-to-anterior
border ~f ramus) to erupt.

FIG. 9-21

FIG. 9-21

FiG. 9-21 Pel! and Gregory class 2 impaction. Approximately .half
is covered by anterior portion of ramus of mandible.

 

 

 

 

 

Angulation

Angulation

The first classification system employs a description of the angulation of the long axis of the impacted third molar _vith respect to the 19n9 axis of the second molar. Because teeth at certain inclinations have ready-made
pathways for withdrawal, whereas pathways for teeth of other inclinations require the removal of substantial amounts of bone, this classification system provides an initial evaluation of the difficulty of extractions.
The mesioangular impactlon is generally acknowledged as the least difficult impaction toremove (Fig. 9-16). The mesioangular-impacted tooth is tilted toward the second molar in a mesial direction. This type of impaction is also the most commonly seen and comprises approximately’ 43% of all impacted teeth. In a severe mesial inclination the impacted tooth is
horizontal (Fig. 9-17). This type of impaction is usually considered ‘110re difficult to remove than the mesioangular impaction. Horizontal impactions occur I~s frequently and are only seen in approximately 3% of all mandibular impactions.

FIG. 9-16 A,

FIG. 9-16 A,

FIG. 9-16 A, Mesioangular impaction-most common and easiest impaction to remove. 8, Mesioc
angular impaction is usually in close proximity to second molar

FIG. 9-17 A,

FIG. 9-17 A,

FIG. 9-17 A, Horizontal impaction-uncommon and more difficult to remove than me~ioangular impaction. 8, Occlusal surface of horizontal impacted third molar is usually immediately adjacent to root of second molar, which often produces early severe periodontal disease In the vertical impaction the long axis of the impacted toorn runs in the same direction as the long axis of the second molar. This impaction occurs with the second greatest frequency, accounts for approximately 38% of all impact” and is t rd in difficulty of removal (Fig.9-18). Finally, the  istoangular impaction is the tooth. with the mo t difficult angulation for removal (Fig. 9-19). In the distoangular impaction the long axis of the third molar is distally or posteriorly angled away from second molar. This impaction is the most difficult to remove because the tooth has a  ithdrawal pathway that runs into the mandibular ramus, and its removal requires greater surgical int~rvention. Distoangular impactions occur uncommonly and account for- only approximately 6’Yo) of all impacted third molars. Erupted third molars may be in a distoanguli\r position. When this occurs, they are extremely difficult to remove routinely, compared with the removal of other erupted teeth.

FIG. 9-18

FIG. 9-18

A, Vertical impaction-second most common impaction and second most difficult to
remove. B, Vertical impaction is frequently covered on its posterior aspect with bone of anterior ramus
of mandible.
A

FIG. 9- 19

FIG. 9- 19

A, Distoangular impaction-uncommon and most difficult of the four types to remove. B, Occlusal surface of distoangular impaction is usually  mbedded in ramus of mandible and requires significant bone removal for extraction. In addition to the relationship between the angulation of the long axes of the second and third molars, the teeth . can also be angled in a buccal or lingual direction. As is noted earlier, the linguocortical plate of the mandible becomes thinner as it progresses posteriorly. Therefore most mandibular third molars are angled toward the lingual direction orin lingual version. Occasionally, a tooth is angled toward the buccal aspect of he mandible or in bucca I version.; Itt[ciy a tooth is a transverse impaction, that is, in an absoluiotv horizontal position in a buccolingual direction. The OCclusal surface of the tooth can face either the buccal or lingual direction. To determine buccal or lin- . gual version accurately, the dentist must take a perpen

perpendicular
occlusal film. However, this determination is usually not necessary, because the surgeon can make this identification early in the operation, and the buccal or lingual position of the tooth does not greatly influence
the difficulty of the surgery

 

 

 

 

CLASSIFICATION SYSTEM OF IMPATED TEETH

CLASSIFICATION SYSTEM OF IMPATED TEETH

Removal of impacted teeth can be either extremely difficult or relatively straightforward and easy. To determine the degree of difficulty preoperatively, the surgeon should examine the patient methodically. The primary factor determining the difficulty of the removal is accessibility.
Accessibility is determined by the case of exposing the tooth, of preparing a pathway tor its delivery, and of preparing a purchase point (or taking advantage of a natural purchase point). With careful classification of the
impacted teeth using a variety of systems, the surgeon can approach the proposed surgery in an orderly fashion and predict whether any extraordinary surgical approachesappraches will be necessary or if the patient will encounter any postoperative problems. ‘ The majority of the classifying results from analysis of the radiograph. For most situations the periapical radiograph provides adequate detail and should be the radiograph most commonly used. The panoramic radiograph
shows a more accurate picture of the total anatomy of the
region and can be used as an adequate substitute. For each patient the dentist should carefully analyze the factors discussed in this section. By combining these factors, the dentist can assess the difficulty of the surgery
and elect to extrat the impacted teeth that are within his skill level. However, for ‘the patient’s sake the dentist should refer the patient to a specialist if a tooth presents a difficult surgical problem.

 

 

Summary

Summary

The preceding discussion of indications and contraindications
for the removal of impacted third molars has
been designed to point out that there are various risks
and benefits for removing impacted teeth in patients.
Patients who have one or more pathologic symptoms or
problems should have their impacted teeth removed.
Most of the symptomatic, pathologic problems that result
from impacted third molars occur because of partially
erupted teeth and occur less comtnonly with a complete
bony impaction. _.
It is less clear what should be done with impacted
teeth before they cause symptoms or problems. In making
a decision as to whether or not an impacted third
molar should be removed, a variety of factors must be
tonsidered. First, the available room in the arch into
which the tooth can erupt must be considered. If adequate
room exists, then the clinician may choose to defer
removal of the tooth until eruption is complete. A second
consideration is the status of the impacted tooth and the

FIG.9-15

FIG.9-15

FIG.9-15 lnipacted maxillary right third molar in 63-year-old patient. This molar should not be extracted b(:cJUSC it is deeply embedded and no signs of disease are present

age of the’ patient. It is critical to remember that the average age of complete eruption is 20, but that eruption may continue to occur up to age 25. A tooth that appears to be a mesioangular impaction at age 17 may eventual-ly become more vertical and erupt +nto the mouth. If insufficient
room exists to accommodate the tooth and a soft tissue operculum exists over the posterior aspect, then pathologic sequelae are likely to occur.
Although there have been some attempts at making very early predictions of whether or not a tooth was going to be impacted, these efforts have not yet resulted in a reliable predictive model. However, by the time the
patient reaches age 18, the dentist and surgeon can reasonably predict  hether there will be adequate room into hich the tooth can erupt with  sufficient clearance of the anterior ramus to prevent soft tissue operculum formation. At this time, if surgical removal is chosen, soft tissue and bone tissue healing will occur at its maximal level. At age 18 or 19, if the diagnosi for inadequate room for functional eruption can be made, then the asymptomatic third molar can be removed and the long-term periodontal health of the second molar will be maximized.

 

 

 

Probable Excessive Damage to Adjacent Structures

Probable Excessive Damage to Adjacent Structures

If the impacted tooth lies in an area in which its removal may seriously jeopardize adjacent nerves, teeth, or previously constructed bridges, it may be prudent to leave the tooth in place. When the dentist makes the decision not to remove a tooth, the reasons must be weighed against potential future cornpllcations. For younger patients who may suffer the sequelae of impacted teeth, it may be wise to remove the tooth while taking special measures to prevent damage to adjacent structures. However, for theolder patient with no signs of impending complications and for whom the probability of such complications. is low, the impacted tooth should not be removed. A classic example of such a case is the older patient with a potentially severe
periodon  I defect on the distal aspect of the second molar but in whom removal of the third molar would almost surely result in the loss of the second molar; In this situation the impacted tooth should not be removed.

Compromised Medical Status

Compromised Medical Status

Similar to extremes of age, compromised medical status may contraindicate the removal of an impacted tooth, Frequently, compromised medical status and advancing age go hand-in-hand. If the impacted tooth is  symptomatic, its surgical removal must be viewed as elective. If the patient’s cardiovascular or respiratory function or host defenses for combating in ection ‘are  compromised Of the patient has a serious acquired or congenital coagulopathy, the surgeon must consider leaving the tooth in the alveolar process. On the other hand, if the tooth becomes symptomatic, the surgeon must work carefully with the patient’s physician to remove the tooth with the
least operative and postoperative medical sequelae.

Extremes of Age

Extremes of Age

The third molar tooth bud can be radiographically visualized by age 6. Some surgeons think that removal of the tooth bud at age 7 to 9 can be accomplished with minimal surgical morbidity and therefore should be per- ‘formed at this age. However, most surgeons believe that
it is ot possible to predict accurately if the forming third molar will be impacted. The consensus is that very early removal of third molars should be deferred until an accurate diagnosis of impaction can be made. The most common contraindication for the removal of impacted teeth is advanced age. As a patient ages the bone becomes highly calcified, therefore less flexible and less likely to bend under the forces of tooth extraction. The result is that more bone must be surgically removed to displace the tooth from its socket. Similarly, as patients age, they respon  Jess favorably
and with more p stoperative sequelae. An I8-year-old patient may have 1 or 2 days of discomfort and swelling after the removal of an impacted tooth, whereas a similar procedure may result in a -i- or S-day recovery period for   50-year-old patient. Finally, if atooth’ has been retained in the alveolar process for many years without periodontal disease,
caries, or cystic degeneration, it is unlikely that these unfavorable sequelae will occur. Therefore in an older patient uisually over age 35) with an impacted tooth that shows no signs of disease and that has a radiographically detectable layer of overlying bone, the  ooth should not
be removed (Fig. 9-15). The dentist caring for the patient should check the impacted tooth radiographically every 1 or 2 years to ensure that “no adverse sequela occurs  If the impacted tooth shows signs of cystic formation or periodontal disease involving either the adjacent toothor the impacted tooth, if it is a single impacted tooth underneath a prosthesis with thin overlying bone. or ii it becomes symptomatic as the result of infection, the tooth must be removed.

CONTRAINDICATIONS FOR REMOVAL OF IMPACTED TEETH

CONTRAINDICATIONS FOR REMOVAL
OF IMPACTED TEETH

All impacted teeth should be removed unless specific contraindications justify leaving them in position, Whenthe potential benefits outweigh the potential complications and risks, the procedure should be performed, Similarly, when the risks are great er than the potential. benefits,
the procedure should be deferred. Contraindications for the removal of impacted teeth , primarily involve the patient’s physical status. FIG. 9-14

FIG. 9-14

FIG. 9-14 Fracture of mandible that occurred through location of
impacted third molar

 

Optimal Periodontal Heaiing

 Optimal Periodontal Heaiing

As noted earlier, one of the most important indications for .removal of impacted third _ars is to preserve the, f:~nodontal healtl •. A great deal of attennon has been given to the two primary parameters of periodontal

FIG.9-10

FIG.9-10

FIG.9-10 Impaction in atrophic mandible, which may result in jaw
fracture during extraction.

health after third molar surgery; that is, bone height on
the distal aspect of the second molar and attachment
1L\’e1 on the distal aspect of the second molar.
Recent studies have provided information on which to
bast.’ the likelihood of optimum periodontal tissue healing.
II.IS The two most important factors have been
shown to be the extent of the preoperative infrabony
defect on the distal aspect of the second molar and the
patient’s age at the time of surgery. If a large amount of
distal bone is missing because of the ‘presence of. the
impacted tooth and the associated follicle, it is less likely
that the infrabony pocket can be decreased. Likewise, if
the patient ,is older, then the Iikelihood of optimum bony
healing is decreased. Patients whose third molars are
removed before age 2S are more Ilkely t~ have better bone

FIG. 9-11

FIG. 9-11

 

FIG. 9-11 Small dentigerous cyst arising around impacted tooth.

FIG. 9-12

FIG. 9-12

FIG. 9-12 Large dentigerous cyst that extends jrorn coronoid
process to mental foramen. Cyst has displacecfimpacted t,hird molar
to inferior border of mandible.

, (, 9- 13

, (, 9- 13

healing than those whose impacted teeth are removed after age 25,14 In the younger patient, not only is the ini-. tial periodontal healing better but the long-term continued regeneration of the periodontium is clearly better. H As mentioned previously, unerupted .teeth may continue to erupt untilage 25. Because the terminal portion of the eruption process occurs relatively slowly, the chances of developing ‘pericoronitis increase, as do the amount of contact between the third molar and second molar. Both of these factors decrease the possibility for ‘ optimum periodontal healing. However, it should be noted that the completely bony impacted third  molar in a patient older than age 30 should probably be left in place unless some specific pathology develops. Removal of such asymptomatic completely impacted-third molarsin older patients will clearly result in pocket depths and alveolar bone loss, which will be greater than if the tooth were left in place