DISCUSSION
KMs or ‘rosette formation’ is a rare phenomemon first described in 1973 where the molars are in occlusion within a single, enlarged follicular space.13 The incidence of KMs has been reported to be 0.06%, being higher in males with an age range of 13-58 years.5,8 Majority are unilateral and occur in the mandible, although bilateral cases have been reported.6,13-19 In the present case, the patient presented with bilateral KMs as an incidental finding. Past medical history may be significant in the occurrence of KMs which may imply that they are a manifestation of diseases rather than independent entities occurring in otherwise healthy individuals. Notably, mucopolysaccharidosis is implicated in some cases with KMs.18 Existing literature was reviewed extensively and a summary of the type of KMs, symptoms, associated disease and treatment presented (Table 1).
Management of symptomatic KMs necessitates surgical intervention whilst that of asymptomatic KMs entails maintenance of the molars within the jaw or surgical disimpaction.20 Maintenance could lead to complications such as reduction of mandibular bone mass over time hence increasing risk of fracture, dentigerous cyst formation, root resorption, pericoronitis, compression of the inferior alveolar nerve (IAN) leading to paresthesia of the lip and functional impairment.7,15,21,22 On the other hand, numerous complications may occur intra-operatively and post-operatively following surgical disimpaction. These include fracture of the mandible due to thinning of cortical bone, damage to the IAN and lingual nerve, temporomandibular joint disorders and infections.14,15,19,23,24,25,26 Therefore, comprehensive clinical and radiographic investigation must be done prior to management.19 As pertains the current case, there was contact between 37 and 47 root apices with the IAN and curvature of the tooth roots. Additionally, the distance to the inferior border of mandible was considerably reduced hence increasing the risk of fracture during surgical disimpaction. These findings informed the decision to maintain the KMs within the jaw and review the patient annually.
Anatomic variations of maxillary second premolars are well documented in the literature, however, trifurcated second premolars are rare.27-31 (Table 2) Knowledge of such variation is crucial during endodontic treatment of the premolar which may necessitate modification of the typical access cavity and consequent technique of management.28,32 Visualization of the third root (palatal root) of the premolar can be challenging on plain radiographs due to superimposition of the buccal roots.33,34 The panoramic image in this case (figure 1 ) is a good example of the latter, whereby superimposition of the mesiobuccal roots concealed the palatal roots. If the mesiodistal width of the mid-root image is equal to or greater than the mesiodistal width of the crown, three canals should be suspected.35 The clinician should have a thorough understanding of the anatomy of the pulp chamber and root canal system along with possible departures from the norm prior to performing any endodontic therapy. In addition, good illumination and magnification can greatly improve visualization of canals and improve management of complex root canal systems.36