This case study reports on the multidisciplinary management of a maxillary canine which sustained an unusual labial crown root fracture, resulting in a large veneer-like fragment. The canine was extruded orthodontically and the fragment was re-attached using adhesive materials. This multidisciplinary solution prevented impingement on the biological width, loss of vitality and loss of tooth structure, leading to an optimal soft and hard tissue aesthetic result. Successful clinical and radiographic results after three years were observed, despite canine protected occlusion.
Clinical Relevance: Multidisciplinary management can result in an improved prognosis of the tooth and, in time, may be the most cost-effective solution for the patient. When discussing treatment options with the patient, utilization of all dental specialties should be considered and offered to the patient.
Article
Dental trauma is common among young patients and is the biggest cause of loss of pulpal vitality.1 Crown root fractures most often occur following horizontal impact1 and can result in unpredictable restorations due to compromised tooth support, bone support and soft tissue support.2
The clinician must first decide upon the final location of the margin of the restoration. Biological width is the minimum soft tissue attachment between the base of the gingival sulcus and the alveolar crest that is necessary for a healthy existence of bone and soft tissue adjacent to a dental restoration.3 Maintaining this width is of utmost importance. Accepting a subgingival restoration impinges on the biological width, resulting in uncontrolled crestal bone resorption and apical migration of the attachment, which in turn results in the formation of a long junctional epithelium4 with an unnatural gingival contour. A subgingival restoration may also lead to plaque retention, causing gingival inflammation and hyperplasia, which may compromise the tooth further. Pulpal complications and difficulty gaining moisture control all limit the options available to the clinician and the patient, traditionally resulting in a less than ideal outcome.
Orthodontic extrusion, surgical crown lengthening, or a combination of the above, can limit this. Orthodontic treatment can also lead to a better prognosis of restorations by improving the position of the teeth and resulting occlusion.5
The clinician must also decide how to restore the tooth. Traditionally, conservative treatment would have been the addition of a composite resin restoration. However, with the advent of more predictable dentine bonding, tooth fragments are increasingly being re-attached to the fractured tooth.2,6,7 Advantages of this include better aesthetics, less interference with occlusion, decreased wear rates and a shorter treatment time.8 Studies have shown that adequate preparation of the fragment and the use of composite resin between fragments can have good survival rates2,7 and improved physical properties, such as increased wear resistance and fracture resistance.9,10
Case study
An 18-year-old male was referred to the trauma clinic of the Dublin Dental Hospital one month after an alleged assault.
The maxillary right permanent canine had sustained a vertical, shear, uncomplicated crown-root fracture extending 3.5 mm subgingivally. The outline of the pulp chamber was clinically visible. An initial treatment of an indirect pulp cap, using hard-setting calcium hydroxide, Dycal®, (Dentsply), Ketac™ Bond Glass Ionomer Liner/Base (3M ESPE), and a composite resin restoration, had been completed within 12 hours of the trauma by a GDP in private practice who then referred him to the Dublin Dental School and Hospital. The fragment had been retained in water by the patient. On examination, the tooth was vital and not showing any clinical or radiographical adverse signs or symptoms. The patient desired to retain the tooth (Figures 1 and 2).
Accepting the existing composite resin restoration and monitoring for loss of vitality and/or gingival irritation. This would impinge on the biological width. There are also limitations of composite resin as a permanent restoration such as microleakage, discoloration and fracture.11
Orthodontically extruding the canine to restore the tooth with the fragment/porcelain or composite veneer/crown. This would restore biological width and give a range of restorative options.
Surgical crown lengthening and restoration of the tooth with the fragment/porcelain veneer/crown. This would restore biological width but would result in asymmetry of the gingival margins.
Elective devitalization of the tooth followed by a post core crown. This would weaken the tooth, which was in canine guidance.
Extraction and replacement with an implant/bridge/removable partial denture. The patient wanted to avoid extraction, if possible. Extraction would also result in localized loss of alveolar bone height.12
Following assessment in a joint orthodontic/restorative clinic, the decision was made to extrude the tooth orthodontically by 2 mm, bond the fragment back into its original position and then re-shape the canine to its original height.
Clinical features that favoured this decision included:
The vitality of the tooth;
The relatively long root length;
The clean fracture; and
The co-operation of the patient.
Clinical features that were disadvantageous included:
The heavy canine guided occlusion of the patient, which would increase the shear stress on the restoration;
The reliance on dentine bonding, which has been shown to be poor in comparison to enamel bonding; and
The short mesial and distal walls decreasing the retention of the restoration.
Treatment
The maxillary teeth were bonded with brackets of 0.022″ x 0.028″ slot size Roth prescription (Ormco Corporation CA, USA). A bracket was placed on the gingival margin of the composite restoration of the canine. The tooth was extruded over a period of six months and the brackets were debonded using a tungsten carbide debond bur with irrigation. In the interim, the tooth fragment was retained in plain water by the patient.
Impressions were taken for study casts and were mounted using a facebow (Whip Mix Quick Mount) and a semi-adjustable ARCON articulator (Whip Mix model 2240), for assessment purposes.
The original composite resin restoration was removed with a tungsten carbide debond bur, copious amounts of irrigation and high volume suction. The outline of the pulp chamber was visible. Hard-setting calcium hydroxide (Dycal®, Dentsply) and resin-modified glass ionomer (Vitrebond™, 3M ESPE) were placed to dress and seal the pulp. The fragment was relieved in this area to compensate for the pulp dressing. Gingival retraction cord was placed and the fragment was bevelled cervically to increase retention and prevent irritation to the gingiva on insertion. Both the tooth and the fragment were prepared with acid etch (Enamel preparator™, Ivoclar Vivadent) and two layers of combined primer/adhesive (Bond 1™, Pentron Clinical Technologies LLC). Alignment of the two segments was achieved and they were bonded together using a flowable composite resin restoration material (X-flow™, Dentsply GAC International). Care was exercised to remove any excess composite. The incisal 2 mm of the canine was then trimmed to optimize occlusion and achieve a natural and aesthetic position in the arch using composite polishing burs and Sof-Lex™ discs (3M ESPE).
Two weeks post-operatively the patient was reviewed. There were no adverse signs/symptoms or post-operative sensitivity. Upper and lower impressions were taken for post-operative study models and an upper Essix retainer was fabricated.
Three years post-treatment the tooth remains vital, in function and displaying no adverse signs or symptoms clinically or radiographically (Figures 3–5).
Figure 3. Intra-oral periapical 3 years post-operatively. The tooth is still vital.Figure 4.
(a) Patient in maximum intercuspation positon. (b) Patient in protrusive excursion. (c, d) Patient showing bilateral canine guidance.Figure 5. Smile line and aesthetic result.
Discussion
Orthodontic extrusion has long been used as an adjunct in restorative dentistry.13,14,15 Recent publications have described the use of orthodontic extrusion for non-vital crown root fractures.16,17 Very few case studies have been reported on the use of orthodontic extrusion on a vital traumatized tooth. Provided that the damage is solely to hard tissues, orthodontic treatment has been shown to have an insignificant effect on pulpal vitality.18 The above case gives an example of how orthodontics may be used to achieve an enduring restoration from an unusual fracture in a canine protected occlusion. Orthodontic extrusion has been shown to be less traumatizing to the tooth than surgical extrusion19 and is less invasive than crown lengthening. Whilst providing the necessary supragingival tooth structure for restoration, it idealized the position of the canine in the arch and allowed complete soft tissue control, avoiding recession and loss of bony support. Re-attachment of the fragment did not necessitate further tooth structure removal. Dentine bonding has been shown to have 5-year success rates of up to 100%, depending upon the type of system used.20 The 5-year failure rate of porcelain fused to metal crowns is just under 5%,21 with the need for endodontic treatment being one of the most common complications.22 The average lifespan of a composite resin restoration is 6 years.23 Every time a new restoration is replaced, further tooth structure is removed. Should the adhesive bond fail, in this case between the tooth and fragment, there is enough supragingival tooth structure available for a reliable restoration to be placed. Should the removal of tooth structure be necessary in order to place a definitive restoration, the formation of a dentine bridge will reduce any further insult to the pulp.
Conclusion
This case study shows the advantages of minimally invasive treatment in order to improve the prognosis of an unusually traumatized tooth. Should this treatment fail, conventional restorative options are still available to the patient. The initial orthodontic treatment provided ensures that the tooth may be restored in future with minimal complications. By delaying the placement of a crown, tooth structure and expense will be saved.
