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The monster permanent maxillary lateral incisor

Published: December 2016


Bulletin # 61 December 2016

The monster permanent maxillary lateral incisor

If you go to the archive at the right side of this page, to the Newsletter bulletin #14 for the month of September 2012, you will see the case presentation of a child in the early mixed dentition in which a “monster” maxillary permanent central incisor had recently erupted on the right side, with two talon cusps on its mesial aspect. On the left side, the central incisor location was occupied by a newly-erupted supernumerary tooth (mesiodens), which was smaller than a normal central incisor, while the permanent central incisor was impacted relatively high in the alveolus.

If the supernumerary tooth were to have been extracted, it would have been a relatively simple matter to resolve the impaction of the central incisor. However, the existence of the monster right central incisor occupying more than its fair share of space would not permit sufficient space for the right lateral incisor and, in any case, it was unsightly. Because of the size of the pulp chamber and because of the excessive width of the cervical area, the tooth could not be sectioned in such a manner as to leave a viable periodontal attachment.

As an integral part of the treatment plan, therefore, the monster tooth was extracted. The supernumerary tooth in the location of the left central incisor was moved to the right, across the facial midline and into the location of the extracted right central incisor, drawing the incisal papilla and the labial frenum with it. The impacted left central incisor erupted autonomously into the arch and into the space vacated by the supernumerary tooth and was then brought into alignment in its designated location. The crown of the supernumerary tooth was finally enlarged to substitute for the missing right central incisor.

December_2016_Fig._1aDecember_2016_Fig._1b

Fig. 1a, b. Intraoral photographs of the patient. The left maxillary lateral incisor (arrow) is considerably larger than the adjacent central incisor, causing crowding of the teeth in the adjacent area.

In the case discussed on the present bulletin, a 10 year old female had erupted a similar monster tooth, which was considerably larger than the adjacent maxillary left central incisor, but this tooth was in fact the maxillary left lateral incisor (Fig. 1). It had erupted adjacent to the left central incisor and had caused the left canine to erupt buccally ectopic and to be crowded out of the dental arch. For this patient, however, there was no supernumerary tooth that could be used as a “spare” to substitute for the monster tooth, were it to be extracted. As in the earlier case and because of the size of the pulp chamber, the fused root and the excessive width of its cervical area (Fig. 2), sectioning could not be advised because the remainder of the tooth would be severely periodontically compromised with a zero prognosis.

The clinical options available were therefore as follows:-

1. Extract the oversized lateral incisor and eventually replace it with an implant. Given her age, this would only be 12 years or so later and would therefore demand long term retention and suitable temporary prosthetic rehabilitation, in the short to medium term.

2. Extract the oversized lateral incisor and immediate replacement with autotransplanted premolar.

3. Extract the oversized lateral incisor and draw the canine mesially as a substitute and to grind its crown or otherwise disguise it to simulate the extracted tooth.

Most of us would have stopped there, in the knowledge that orthodontics has nothing further to offer in terms of a treatment plan.

There is, however, a non-extraction approach to this problem, which was employed in relation to the following short case report.

This young patient was a healthy child and was first examined by me in January 2013. She only returned in October 2014 to begin treatment. In the initial orthodontic examination, she exhibited a late mixed dentition exhibiting close-to-normal alignment and intermaxillary relations. In the right side of the maxilla, the deciduous canine and both deciduous molars were present, while on the left side, the first premolar and canine were already erupting together with the retained deciduous second molar. The oversized lateral incisor was seen on the left side of the maxilla. In the mandibular arch all deciduous teeth had shed, with eruption of the premolars and second permanent molars.

December_2016_Fig._2aDecember_2016_Fig._2c

Fig. 2a. a panoramic view of the dentition.

Fig. 2b. the immediate area of the lateral incisor enlarged to show detail.

Fig. 2c. an axial cut across the cervical third of the anterior teeth shows the very broad mesiodistal width of the affected lateral incisor.

A panoramic film taken at that time showed all permanent teeth developing. The four residual deciduous teeth in the maxilla were defined as over-retained by dint of the fact that the unerupted premolars and right canine featured root development in excess of 2/3 their final length. The lateral incisor was seen to have 2 fused roots and a broad cervical width at the cemento-enamel junction (Fig. 2).

December_2016_Fig._3

Fig. 3. The initial appliance set-up, with 0.014’ nickel-titanium levelling arch, by-passing the left lateral incisor.

December_2016_Fig._4

Fig. 4. An eyelet is bonded to the mesial corner of the lateral incisor and progressively rebonded more mesially, to effect the 900 rotation of the tooth.

December_2016_Fig._5

Fig. 5a. An occlusal view of the bonded eyelet on the partially rotated tooth.

Fig. 5b. An occlusal view following completion of the rotatory movement. Root canal therapy has been performed and the form of the crown of the tooth altered in preparation for a semi-permanent restoration.

The orthodontic treatment plan was as follows:-

1. Level and align the maxillary dentition, while by-passing the left lateral incisor (Fig. 3).

2. Perform root canal therapy on the incisor to permit crown reshaping.

3. Rotate the lateral incisor through 900 while reducing the incisal edge to avoid premature contact with the mandibular incisors (Fig. 4).

4. Reduce the anatomical mesiodistal width of the crown (Fig. 5).

5. Level and align the mandibular dentition.

6. Coordinate arches.

7. Debond and deband (Fig. 6) and place fixed mandibular canine-to-canine twistflex bonded retainer. Place removable upper retainer to permit prosthodontic alteration of the maxillary lateral incisor while maintaining alignment.

8. Complete construction and fitting of a semi-permanent crown/laminate at maxillary left lateral incisor.

9. Substitute maxillary canine-to-canine twistflex bonded retainer and discard removable retainer.December_2016_Fig._6aDecember_2016_Fig._6b

Fig. 6a, b. Intraoral photographs of the dentition on the day the appliances were removed.

December_2016_Fig._7

Fig. 7. A panoramic view of the dentition in general and a periapical radiograph of the treated lateral incisor.

An orthodontic appliance was placed in the maxilla October 2014 (Fig. 3) and in the mandible only in March 2016. The fixed appliances were removed in October 2016 after 24 months of active orthodontic treatment. During the rotation of the tooth, much enamel reduction was performed to eliminate occlusal trauma and, additionally to reduce its excessive coronal bulk. Root canal treatment was carried out by Dr. Maury Sommer when the tooth became sensitive, to permit more radical crown reshaping (Fig. 7). The referring prosthodontics specialist was Dr. Hillel Baruch, who was responsible for having originally suggested the solution of rotating the incisor through 900, recognizing that the bucco-lingual profile of its CEJ area of the root was similar in width to the mesio-distal width of a normal lateral incisor (Fig. 2).