Principles of Management of Impacted Teeth Larry 1. Peterson INDICATIONS FOR REMOVAL OF IMPACTED TEETH CLASSIFICATION SYSTEMS OF IMPACTED TEETH Prevention of Periodontal Disease Angulation Prevention of Dental Caries Relationship to Anterior Border of Ramus Prevention of Pericoronitis Relationship to Occlusal Plane Prevention of Root Resorption Summary Impacted Teeth under a Dental Prosthesis ROOT MORPHOLOGY Prevention of Odontogenic Cysts and Tumors Size of Follicular Sac Treatment of Pain of Unexplained Origin Density of Surrounding Bone Prevention of Fracture of the jaw Contact with Mandibular Second Molar Facilitation of Orthodontic Treatment Relationship to Inferior Alveolar Nerve Optimal Periodontal Healing Nature of Overlying Tissue CONTRAINDICATIONS FOR REMOVAL OF IMPACTED MODIFICATION OF CLASSIFICATION SYSTEMS FOR TEETH MAXILLARY IMPACTED TEETH Extremes of Age DIFFICULTY OF REMOVAL OF OTHER IMPACTED TEETH Compromised Medical Status SURGICAL PROCEDURE Probable Excessive Damage to Adjacent Structures PERIOPERATIVE PATIENT MANAGEMENT Summary n impacted tooth is one that fails to erupt into the Teeth most often become impacted because of inade- dental arch within the expected time. The tooth quate dental arch length and space in which to erupt; becomes impacted because adjacent teeth, that is, the total length of the alveolar bone arch is small- d' dcnse overlying bone, or excessive soft tissue prevents er than the total length of the tooth arch. The most com- eruption. Because impacted teeth do not erupt, they are mon impacted teeth are the maxillary and mandibular retained for the patient's lifetime unless surgically removed. third molars, followed by the maxillary canines and The term lrtzerilpted includes both impacted teeth and mandibular premolars. The third molars are the most fre- teeth that are in the process of erupting, The term embed- quently impacted, because they are the last teeth to cld is occasionally used interchangeably with the term erupt; therefore they are the most likely to have inade- impnctod. quate space for eruption. Principles of Management of lmpocted Teeth m CHAPTER 9 185 In the anterior maxilla, the canine tooth is also com- and are relatively superficially positioned with respect to monly prevented from erupting by crowding from other the occlusal plane of the adjacent second molar. teeth. The canine tooth usually erupts after the maxillary Finally and perhaps most importantly, sufficient space lateral incisor and maxillary first premolar. If space is exists between the anterior border of the ramus and the inadequate to allow eruption, the canine tooth becomes second molar tooth to allow erupti~n.',~Likewise, if the impacted. In the anterior mandible a similar situation tooth does not erupt after age 20, it is most likely covered affects the mandibular premolars, because they erupt with bone. In addition, the tooth is likely a mesioangular after the mandibular first molar and mandibular canine. impaction and located lower in the alveolar process near Therefore if room for eruption is inadequate, one of the the cervical level of the adjacent second molar. Finally, premolars, usually the second premolar, remains un- inadequate space exists to allow eruption. Therefore the erupted and becomes impacted. dentist and surgeon can use these parameters to predict As a general rule, all impacted teeth should be re- whether or not a tooth will erupt into the arch or remair! moved unless removal is contraindicated. Extraction impacted. should be performed as soon as the dentist determines Early removal reduces the postoperative morbidity and that the tooth is impacted. Removal of impacted teeth allows for the best healing.3-"ounger patients tolerate becomes more difficult with advancing age. The dentist the procedure better and recover more quickly and with should not recommend that impacted teeth be left in less interference to their daily lives. Periodontal healing is place until they cause difficulty. If the tooth is left in better in the younger patient, because of better and more place until problems arise, the patient may experience an complete regeneration of the periodontal tissues. More- increased incidence of local tissue morbidity, loss of adja- over, the procedure is easier to perform in younger cent teeth and bone, and potential injury to adjacent patients. The ideal time for removal of impacted third vital structures. Additionally, if removal of impacted molars is when the roots of the teeth are one-third teeth is deferred until they cause problems later in life, formed and before they are two-thirds formed, usually surgery is more likely to be complicated and hazardous, during the late teenage years, between ages 17 and 20. because the patient may have compromising systemic If impacted teeth are left in the alveolar process, it is diseases. A fundamental precept of the philosophy of highly probable that one or more of several problems will dentistry is that problems should be prevented. Preven- re~ult.~,~To prevent this, impacted teeth should be tive dentistry dictates that impacted teeth are to be removed. removed before complications arise. This chapter discusses the management of impacted Prevention of Periodontal Disease teeth. It is not a thorough or in-depth discussion of the technical aspects of surgical impaction removal. Instead Erupted teeth adjacent to impacted teeth are predisposed its goal is to provide both the information necessary for to periodontal disease (Figs. 9-1 and 9-2). The mere pres- proper management and a basis for determining the dif- ence of an impacted mandibular third molar decreases ficulty of surgery. the amount of bone on the distal aspect of an adjacent second molar (see Fig. 9-1). Because the most difficult tooth surface to keep clean is the distal aspect of the last INDICATIONS FOR REMOVAL tooth in the arch, the patient may have gingival inflam- OF IMPACTED TEETH - - * -- - -- .--- - . - mation with apical migration of the gingival attachment All impacted teeth should be considered for removal as on the distal aspect of the second molar. With even soon as the diagnosis is made. The average age for com- minor gingivitis the causative bacteria have access to a pletion of the eruption of the third molar is age 20, large portion of the root surface, which results in the although eruption may continue in some patients until early formation of severe periodontitis (see Fig. 9-2). age 25. During normal development the lower third Patients with impacted mandibular third molars often molar begins its development in a horizontal angulation, have deep periodontal pockets on the distal aspect of the and as the tooth develops and the jaw grows, the angula- second molars but have normal sulcuIar depth in the tion changes from horizontal to mesioangular to vertical. remainder of the mouth. Failure of rotation from the mesioangular to the vertical The accelerated periodontal problem resulting from an direction is the most common cause of the tooth remain- impacted third molar is especially serious in the maxilla. ing impacted. The second major factor is that the As a periodontal pocket expands apically, it becomes mesiodistal dimension of the teeth versus the length of involved with the distal furcation of the maxillary second the jaw is such that inadequate room exists in the alveo- molar relatively early, which makes advancement of the lar process anterior to the anterior border of the ramus to periodontal disease more rapid and severe. In addition, allow the tooth to erupt into position. treatment of the localized periodontal disease around the As noted earlier, some third molars will continue to maxillary second molar is more difficult because of the erupt after age 20, coming into final position by age 25. distal furcation involvement. Multiple factors are associated with continued eruption. By removing the impacted third molars early, peri- When late eruption occurs, the unerupted tooth is usual- odontal disease can be prevented and the likelihood of ly covered only with soft tissue or very slightly with bony healing and bone fill into the area previously occu- bone. These teeth are almost always in a vertical position pied by the crown of the third molar is increased."-'j 186 PART 11 l'rir1c-i/1lc.~of Exotlor~titr Rad~ographof mand~bularth~rd molar Impacted aga~nstsecond molar, wlth bone loss result~ngfrom presence of th~rdrnolar R,~iiogr,lpi>i,l~ow v,ir~,ilioni 01 rn,~iidil~iilarttl~rd rnolar impacted agai12st srcond molar, with severe bone loss secondary to periodontal disease and third molar. Prevention of Dental Caries Prevention of Pericoronitis When a third molar is impacted or partially impacted, When a tooth is partially impacted with a large amount the bacteria that cause dental caries can be exposed to of soft tissue over the axial and occlusal surfaces, the the distal aspect of the second molar, as ell as to the patient frequently has one or more episodes of pericoro- third molar. Even in situations in which no obvious nitis." Pericoronitis is an infection of the soft tissue communication between the moi~thand the impacted around the crown of a partially impacted tooth and is third molar exists, there may be enough communica- caused by the normal oral flora. For most patients the tion to allow for caries production (Fig$. 9-3 through bacteria and host defenses maintain a delicate balance, 9-5). but host defenses cannot eliminate the bacteria. Principles of M~~r~cz~yt~tnetltuf It?~lxzctr~ri Erc3fll @ CHAPTER 9 187 FIC ' 5 Radiograph of carles In mandibular second molar secondarv to i)lr\t'llic ot rni).tct- ed third molar. If the host defenses are compromised (e.g., during minor illnesses, such as influenza or an upper respiratory infec- tion, or from severe fatigue), infection can occur. Thus although the impacted tooth has been present for some time without infection, if the patient experiences a mild, transient decrease in host defenses, pericoronitis may result.