Inverted and Impacted Maxillary and Mandibular Third Molar: Unusual Case Reports with Review of the Literature.

Inversion has been defined as the malposition of a tooth in which the tooth is reversed and positioned upside down. Very few cases of inverted and impacted third molars have been reported in the literature. The most common location of such a third molar in the mandible is in the ascending ramus. In the maxilla, the teeth may be displaced as far as the floor of the orbit. Two cases of inverted and impacted third molars are described. They were conservatively managed without surgery. The two cases are reported because impaction with inversion of a molar tooth is not common.

INTRODUCTION

An impacted tooth is defined as one which is prevented from its normal path of eruption due to lack of space or obstruction in the eruptive pathway of the tooth. The level of impaction can be determined by the Pell and Gregory classification.[1] Position A: The occlusal plane of the impacted tooth is at the same level as the adjacent tooth. Position B: The occlusal plane of the impacted tooth is between the occlusal plane and the cervical line of the adjacent tooth. Position C: The occlusal plane of the impacted tooth is apical to the cervical line of the adjacent tooth. Position I: Situated anterior to the anterior border of the ramus. None of the third crown is in the ramus of the mandible. Position II: Less than half of the crown is in the ramus of the mandible. Position III: More than half of the crown is in the ramus.[1] Although the most commonly impacted teeth are maxillary and mandibular third molars, inverted impaction of teeth is uncommon , with only a very few cases reported in the literature. In the mandible, the most common location of inverted 3rd molar is in the ascending ramus, whereas, in the maxilla, the impacted teeth may be displaced as far as the floor of the orbit.[2]

This case report describes uncommon cases of inverted and impacted unilateral mandibular as well as maxillary third molars.

CASE REPORTS

Case 1

A 45-year-old male patient reported to the Department of Oral Medicine and Radiology, with the chief complaint of multiple decayed teeth. Clinical intraoral examination revealed dental caries in 17, fractured restoration in 26, root stump of 27, and deep dental caries in 36. Clinically 36, 37 were absent due to extraction a few years before because of pulpal involvement of the teeth. Orthopantomogram (OPG) confirmed the oral findings. The OPG also showed an impacted 18 and inverted 28 impaction. As shown in Figure 1, the crown of the impacted molar was facing the maxillary sinus floor. The patient was informed, but he refused to have surgery to remove the impacted teeth. He was only interested in having the decayed teeth treated. The patient was, therefore, advised to report for periodic follow-up visits.

Figure 1

Orthopantomogram showing inverted impacted left maxillary third molar in Case 1

Case 2

A 50-year-old female patient reported to the Department of Oral Medicine and Radiology with the chief complaint of multiple root stumps in the teeth (of 6 months’ duration) causing discomfort during mastication. Intraoral examination and OPG showed multiple root stumps of 17,14,13,12,11,21,22,23,24,25,32,31,41,42 and missing 16,15,26,27,37,36,35,34, 33,43,44, 45,46,47. In addition, OPG showed inverted 38 impaction with the crown quite close to the mandibular canal and the root apex near the alveolar crest [Figure 2]. The patient was advised to have all root stumps and impacted 38 removed to be followed by complete denture replacement. She, however, declined the surgical treatment.

Figure 2

Orthopantomogram showing inverted impacted left mandibular third molar in Case 2

DISCUSSION

Inversion has been defined as "the malposition of a tooth in which the tooth has reversed and is positioned upside down."[1] Inverted impacted teeth may stay in the same position for a long time without any clinical manifestations. However, they may lead to complications such as crowding, diastema, delayed and ectopic eruption, eruption into the nasal floor, resorption of the adjacent tooth and development of serious pathology.[3] Inverted impaction has been reported in incisors,[4] canines,[5] and premolars.[6] Only a very few cases of inverted and impacted third molars have been reported in the literature. The reason for the inversion of teeth as documented is unusual proliferation of odontogenic epithelium before the development of the tooth germ.[1] In the mandible, the most common location of inverted impacted 3rd molar is in the ascending ramus, whereas, in the maxilla, teeth may be displaced as far as the floor of the orbit.[2] Inverted impaction has been described as complicated as the crown points downwards and root points towards the alveolar crest.[1]

Various factors which may influence impaction of teeth include systemic factors like endocrine deficiency, irradiation, cleidocranial dysplasia, febrile disease, Down's syndrome and local factors such as abnormal eruptive pathway, supernumerary teeth, malposed tooth germs, prolonged deciduous tooth retention, arch length deficiency, odontogenic tumors and cleft lip/palate.[7]

Radiographic imaging plays an important role in detecting the exact position of inverted, impacted teeth and their relation to vital anatomic structures, to prevent their displacement into sinus and infratemporal fossa during surgery. Furthermore, this helps their removal with minimum surgical trauma.[1]

Removal of an inverted, impacted tooth is more complicated than the removal of normally impacted tooth, usually because of the patient's age and the deeper position of the inverted tooth. There is also a need to remove large amounts of bone during surgery as these teeth are completely embedded in the bone. Other possible sequelae of their removal include oro-antral fistula formation, displacement of hard tissue fragment into the sinus, nose or the infratemporal fossa.[8] Besides, there is no clear treatment protocol in the literature, so the clinician must weigh the risks and benefits of removing impacted third molars. Risk factors associated with surgical removal should be properly conveyed to the patient, and a written consent obtained from the patient prior to surgery.

CONCLUSION

Inverted and impacted third molars, whether maxillary or mandibular, are uncommon clinical entities. The dentist should, therefore, be aware of them and be able to assess the level of difficulty posed by each case in order to facilitate the planning of treatment and proper patient management.