Isolated bilateral macrodontia of mandibular second premolars: A case report.

Isolated bilateral macrodontia of mandibular second premolars is an extremely rare dental anomaly with only 5 cases reported to date. This case report presents clinical and radiographic findings of isolated bilateral macrodontia in a 12-year-old child. The patient was referred to the clinic with local crowding of mandibular posterior teeth. Radiographic findings revealed the presence of impacted macrodont mandibular second premolars and their distinct morphological appearance, characterized by large, multitubercular, molariform crowns, and tapering, single roots. Following surgical removal of the impacted premolars, orthodontic therapy was initiated to correct the malocclusion. Along with the features and treatment of this rare anomaly, this case report also illustrates the benefits, in terms of treatment planning and surgical technique, of supplementing conventional radiography with cone-beam computed tomography to localize the macrodont premolars and accurately establish their relationship with the neighboring roots and anatomic structures.

INTRODUCTION

Macrodontia (megadontia, megalodontia, macrodontism), is a rare shape anomaly that has been used to describe dental gigantism.1 Macrodontia is usually associated with systemic disturbances or syndromes such as insulin-resistant diabetes,2 otodental syndrome,3,4 facial hemihyperplasia,5,6 KBG syndrome,7 Ekman-Westborg-Julin syndrome,8 and 47, XYY syndrome.9 Isolated form of macrodontia has been rarely reported.10–13 The prevalence of macrodont permanent teeth is 0.03–1.9%,14–16 with a higher frequency in males.15,16 The pathogenetic mechanism underlying macrodontia is still unknown.

Macrodontia can be differentiated into “true generalized,” “relative generalized,” and “isolated” forms.17 In true generalized macrodontia, all teeth are larger than normal, and the condition may be associated with pituitary gigantism.18 Relative-generalized macrodontia refers to the presence of normal or slightly larger teeth in smaller jaws.19 Isolated macrodontia refers to macrodontia of single teeth, and is an extremely rare condition that may be seen as a simple enlargement of all tooth-related structures20,21 or may be related with morphological anomalies.12,22,23 This type of macrodontia is more frequently found in incisors and canines,24 and has been rarely reported to involve premolars and molars. In particular, macrodontia of premolars is extremely rare and may be confused with fusion or gemination of adjacent teeth to form a single tooth. To date, only 8 cases of isolated macrodontia of second premolars have been reported in the literature; 5 of which have shown bilateral occurrence (Table 1).

Table 1

Summary of published case reports of macrodontia of the mandibular second premolars.

Author	Year	Sides Affected	Eruption Status
Primack	1967	Bilateral	Unerupted
Hermel et al	1968	Bilateral	Erupted
Ekman-Westborg et al	1974	Bilateral	Left Erupted, Right Unerupted
Reichart et al	1977	Unilateral	Unerupted
Peck et al	1983	Bilateral	Unerupted
Groper	1987	Unilateral	Unerupted
Dugmore	2001	Bilateral	Erupted
Rootkin-Gray et al	2001	Unilateral	Unerupted

Depending on their size and morphology, macrodonts can create a variety of functional and esthetic problems that may require endodontic, prosthetic, surgical, and/or orthodontic treatment.12,14,18,23 This case report presents clinical and radiographic findings of isolated bilateral macrodontia of mandibular second premolars.

CASE REPORT

A healthy 12-year-old girl was referred to the Department of Pediatric Dentistry for consultation concerning local crowding associated with macrodontia. The patient’s medical history was unremarkable, and there was no family history of any genetic or dental anomalies. Reportedly, the child had not experienced any trauma related to the jaws. The patient was in the late mixed-dentition stage and had Angle class-III molar relationship. The mandibular and maxillary primary second molars had exfoliated and a large mandibular left second premolar was attempting to erupt between the normal-sized first premolar and the first molar teeth (Figure 1).

Figure 1

View of the premolar regions from both sides.

Radiographic examination of the jaws revealed the presence of mandibular second premolars of abnormal size and morphology (Figure 2). The right premolar was distally impacted and its large-sized, multitubercular crown was in contact with the mesial root of the first molar (Figure 2). The conical root was in close proximity to the inferior alveolar canal and had a large, single root canal space (Figure 2). The left premolar was partially impacted and showed similar crown and root canal morphology (Figure 2).

Figure 2

A. Panoramic radiograph showing macrodont mandibular second premolars. B and C. Periapical radiographs of the right and left premolars, respectively.

Following orthodontic assessment, the patient was scheduled for surgical removal of the macrodont premolars to prevent any possible complications of eruption as well as preparation for consequent orthodontic therapy. Owing to the abnormal angulation of both the premolars, 0.3 mm-thick tomograms were obtained on an ILUMA cone-beam computed tomography (CBCT) scanner (Imtec Corp., Ardmore, OK, USA) to determine their exact position in the vertical and horizontal planes, and thus, facilitate surgical removal with minimal or no damage to neighboring teeth and anatomic structures (Figure 3). The tomograms precisely indicated that the crown of the right macrodont pre-molar was aligned lingually and was in very close proximity to the root of the first premolar. Both the 2- and 3-dimensional tomographic images con-firmed that the second premolars had multitubercular crowns and single conical roots with a large, single root canal space (Figure 3).

Figure 3

Cone beam CT scans of the macrodont premolars: A. Frontal view, B. Horizontal view. 3D tomograms of the jaws (C), and the right (D) and left (E) macrodont premolars, showing their position, size and morphology.

The teeth were surgically removed in 2 consecutive sessions under local anesthesia. Both teeth were sectioned at the cervical level before elevation due to abnormal dimension of the tooth crowns (Figure 4). Healing was uneventful in both the cases. The crowns of the extracted premolars measured 15.3 mm (right) and 13.16 mm (left) mesiodistally, and 10.7 mm (right) and 10.5 mm (left) buccolingually. After 2 months, fixed appliance therapy was initiated by the orthodontist to correct malocclusion.

DISCUSSION

Being an extremely rare condition,13 macrodontia of mandibular second premolars has been reported exclusively in children (8–14 years) with only 1 exception.8 Indeed, disturbances with the eruption of macrodont second premolars and concomitant disruption of developing occlusion or alveolar/gingival enlargement become evident before or between the ages of 11 and 12, when the eruption of mandibular second premolars usually occurs.10 Thus, any intervention should be completed before maturity, and, in light of previous reports, extraction appears to be the only available intervention.10,12,13 Following extraction, orthodontic treatment should be started in a timely manner due to disturbances in the arch and occlusion after surgical intervention.12,18

The interpretation of conventional radiographs is dependent on the clinician’s appreciation as well as his/her knowledge and experience in assessing 2-dimensional images. Radiographic images may fail to locate accurately some anomalies relative to neighboring teeth because of superimposition of adjacent structures. In the present case, the conventional radiographs provided insufficient information to diagnose accurately the location of the macrodont premolars in the vertical and horizontal plane, as well as their exact relationship to the neighboring teeth and inferior alveolar verve. Supplementing plain view radiography with CBCT demonstrated great usefulness in showing the 3-dimensional orientation of impacted premolars within the alveolus, while allowing for detailed, non-destructive investigation of tooth morphology. The additional dose to the patient from the CBCT investigation can be justified by the present case; the information gained was of clear benefit in planning the surgical technique, particularly, in the macrodont left premolar.

Multituberculism has been reported previously in combination with macrodontia and other morphologic anomalies involving the entire dentition.25 Consistent with the present case and previous publications, isolated macrodont premolar teeth are also present in multituberculism.10,12,13 In most cases, a fine pulpal extension has been shown in the dentinal core at the cusp. Invagination could be either the result of active proliferation of an area of the enamel organ with infolding of the proliferating cells into the dental papilla, or of displacement of a part of the enamel organ into the papilla as a result of abnormal pressure from the surrounding tissue.26 Based on the stark similarities in morphology of the isolated macrodont second premolars reported previously, Dugmore10 proposed using the term “macrodont molariform premolars.”

CONCLUSION

Isolated bilateral macrodontia of the mandibular second premolars is an extremely rare dental anomaly, which requires a multidisciplinary-treatment approach along with advanced radiographic assessment.