Endodontic-orthodontic-restorative treatment of a mandibular second molar: a case report on the management of a tooth combining endodontic, orthodontic and restorative treatment

A 42-year-old Caucasian male was referred by his general dental practitioner for endodontic treatment of his mandibular left second molar (tooth 37). On Christmas Day in 1999, the patient had severe pain from tooth 37. The referring dental practitioner initiated root canal treatment but encountered curved root canal anatomy. Treatment was discontinued, calc um hydroxide dressings were placed in the root canals and a referral to the dental hospital was made. The patient had suffered one episode of pain after the initial treatment, which was treated with antibiotics.

Clinical examination

The patient had good oral hygiene. The general periodontal status was good with normal probing profiles. The dentition was moderately restored. In the intercuspal position, the molar relationships were Class I on both sides with multiple contacts
between the upper and lower posterior teeth. The anterior teeth showed normal overbite and overjet.

In the retruded contact position (RCP), the first contacts were between teeth 17 and 46 on the right side and teeth 27 and 37 on the left side. The slide from the RCP to ICP was straightforward with large horizontal and small vertical components. The
condylar movement was mainly translation.

On protrusion, the incisors provided the guidance while canines guided lateral excursions on both sides. No excursive interferences were detected on either side.

Clinical examination of tooth 37 revealed the presence of a temporary restoration. The tooth was mildly tender to percussion and biting. No sinus tract was evident and periodontal probing depths around tooth 37 were within normal limits. Tooth 37 was
observed to have tipped mesio-angularly.

Radiographic examination

A dental panoramic tomograph (DPT) showed a moderately restored dentition with healthy levels of alveolar bone. The DPT also showed an area of radiolucency associated with the distal root of tooth 37. Concurring with the DPT, a periapical radiograph
of tooth 37 revealed the presence of periapical radiolucency in the distal root area. The root canals of tooth 37 were unfilled.

Provisional diagnosis

The toothache experienced by the patient from tooth 37 on Christmas Day was an acute exacerbation of chronic apical periodontitis associated with the tooth.

Treatment plan

Two treatment options for tooth 37 were discussed with the patient. One was to root treat and then upright the tooth orthodontically for placement of a cast gold restoration. The other was to extract it. The patient was motivated to pursue the best longterm treatment outcome for his molar tooth. After understanding the duration of treatment, compliance and prognoses of the various treatment strategies, he elected for root canal treatment of tooth 37 and its subsequent orthodontic and restorative treatment.

Treatment

a. Root canal treatment of Tooth 37
Anaesthesia of tooth 37 was achieved with a local infiltration of 2% lidocaine with 1:80,000 epinephrine.
Tooth 37 was isolated by rubber dam and its temporary restoration removed. An orthodontic band was fitted and cemented onto tooth 37 with Ketac-Fil Plus before endodontic treatment was commenced.

Three canal orifices were identified. The apical parts of the canals and their foramina were explored with size 6 K-Flex files. All the canals appeared to exit distolingually. In particular, that of the distal canal did so at a rather acute angle. The root canals were pre-flared with small size Heström files. Root ZX apex locator zero readings, verified by periapical radiographs, were obtained in all three canals. The working lengths for these canals were established at 0.5mm short of the zero reading lengths.

At the following visit, the canals were prepared to an apical size of 25 using Flexofile and Flexofile Golden Mediums in a watch-winding motion. The taper of the canal was prepared by 0.5mm step-back increments up to size 60. Copious 2.5% sodium hypochlorite irrigation was used and canal patency was maintained with size 10 K-Flex files. Calcium hydroxide, as an intra-canal medicament, was used and the access cavity was sealed with cotton wool pellet and IRM.

The canals were subsequently obturated with gutta percha and Roth sealer using a formed cone technique, cold lateral condensation and Piezon ultrasonic energised spreading. The coronal 3mm of gutta percha was removed from the canals and the access cavity restored with an amalgam Nayyar core.

b. Orthodontic uprighting of tooth 37
For the next phase of the treatment, the patient was referred to the orthodontic department for uprighting of the tooth 37. A compressed coil spring on a round wire (18 mil steel) was used to upright the tooth. This was completed in nine months. The uprighting yielded a greater than expected separation of the molars. It was decided that the excess space would be managed
during the restorative phase using a deliberately under-contoured temporary crown. This allowed a controlled mesial drift and tipping of tooth 37, which eventually eliminated the excess space. The extra space was closed in two months.

c. Diagnostic occlusal adjustment
As there was RCP contact between tooth 37 and its opposing tooth (tooth 27), crown preparation on tooth 37 would eliminate this contact. This may have resulted in an adaptive response that led to a new condylar position, as well as a different path of
closure. This is because without the deflective RCP contact, the mandible could close slightly distally to the original ICP. This can reduce interocclusal space, such that when the crown is fitted it may be found to be ‘high’.

One solution to this potential problem is to eliminate the RCP to ICP slide altogether and restore tooth 37 to RCP. However, to eliminate the slide would require removal of tooth structure. Diagnostic occlusal adjustment on study models was carried out
to assess the amount of tooth tissue that needed to be removed.

The occlusal surfaces of the study models, which were mounted in the RCP, were painted with a layer of blue die relief agent. Occlusal contacts were marked with articulating papers and removed with a scalpel blade. This process was repeated until the RCP became coincident with the ICP.

By inspecting the lower model, it was apparent that tooth tissue would need to be removed from the mandibular right first and second molars, mandibular right first premolar, mandibular left first molar and tooth 37 to make the RCP coincident with the ICP. The amount of tooth tissue removal required was considered unjustifiable. Instead, it was decided that tooth 37 would be restored to ICP, ensuring accurate registration of the ICP, and occlusal adjustment would be made during the fitting of the crown.

d. Preparation of tooth 37 for a gold onlay
After removal of the orthodontic brackets and coil spring, tooth 37 and its amalgam core were prepared to receive an MOD gold onlay. An impression was taken at a subsequent visit. Meanwhile, tooth 37 was temporised with a mesio-proximally under-contoured
provisional crown, which allowed controlled mesial drifting and/or tipping of tooth 37 to close the extra interproximal space.

e. Laboratory procedures
Except for the casting process, the author carried out was seated and inspected for marginal fit, interproximal and occlusal contacts. Once all of these aspects were considered satisfactory, the crown was cemented with zinc phosphate cement.

g. Review
The patient was symptom-free when reviewed at 12 months post-operatively. Although not taken in exactly the same view, comparison of pre-operative and review periapical radiographs showed an increase in bone density around the periapex of the distal root
area of tooth 37.

Discussion

Root treated teeth can be moved as readily and for the same distance as vital teeth (Huettner RJ, Young RW, 1955; Wickwire et al, 1974; Mattison et al, 1983; Hunter et al, 1990; Mah et al, 1996). However, some authors have recommended that for teeth requiring
root canal and orthodontic treatment, the cleaning and shaping of the canals should be carried out first, followed by an interim dressing of calcium hydroxide (Andreasen JO, Andreasen FM, 1994). Canal obturation is only completed after orthodontic treatment. This approach stems from concern that apical resorption, which can occur during orthodontic treatment, may challenge the apical seal.