Journal of Endodontics Research - http://endodonticsjournal.com
Incomplete tooth fracture following root-canal treatment
http://endodonticsjournal.com/articles/79/1/Incomplete-tooth-fracture-following-root-canal-treatment/Page1.html
By JofER editor
Published on 07/28/2002
 
C.D. Lynch & F.M. Burke
Department of Restorative Dentistry, National University of Ireland, Cork, Ireland.

Aim.
To demonstrate the need for proper restoration of root-filled teeth.

Key learning points.
  • Failure to provide a root-filled tooth with a restoration incorporating adequate cuspal protection can lead to subsequent tooth fracture.
  • Large intracoronal restorations should be avoided when restoring root-filled teeth, particularly when marginal ridges have been lost.

A Case Report
C.D. Lynch & F.M. Burke
Department of Restorative Dentistry, National University of Ireland, Cork, Ireland.

Introduction.
Complete or incomplete fracture of root-filled teeth has several aetiologies. It may arise from the excessive removal of tooth substance during instrumentation of the root-canal system (Rosen 1982), followed by the exposure of the already weakened tooth structure to mechanical pressures during obturation (Pitts & Natkin 1983, Dang & Walton 1989, Morfis 1990, Borelli & Alibrandi 1999). Tooth fracture can also occur when root-filled teeth are exposed to significant occlusal force. Such structurally compromised teeth – which may have a reduced level of ‘protective’ proprioception (Loewenstein & Rathkarnp 1955, Randow & Glanz 1986) and are sometimes regarded as more brittle than natural teeth (McLean 1998) – are noted to be at risk of fracture development (Shillingburg et al. 1997). The final coronal restoration should be designed to include adequate cuspal protection (Rosen 1982).
Extensively restored teeth are more likely to develop fractures (Cameron 1964). As rootcanal treatment is often performed on the teeth that have extensive restorations, these teeth should be investigated for existing fractures before commencing the treatment.
Tooth fractures impair the patient’s masticatory performance. They also compromise the survival of root-filled teeth, as they may contribute to the progression of periodontal destruction in the presence of apparently successful root fillings (Polson 1977).
The following case describes the development of an incomplete tooth fracture in a root filled mandibular molar.

Report.
A 39-year-old female patient was referred to the Department of Restorative Dentistry, University Dental School and Hospital, Cork, Ireland. Following root filling of the mandibular left first molar 2 years prior to the referral, a radiolucency suggestive of a fracture in the furcation area was noted (Fig. 1). The tooth had been restored with an extensive foursurface (mesio–occlusal–disto–buccal) intracoronal restoration of a silver-reinforced glassionomer cement (Ketac-Silver, ESPE Dental AG, Seefeld, Germany). An ‘overt’ fracture had developed clinically on the mandibular first left molar, running from the buccal surface to the distal surface, along the margins of the restoration, separating the tooth into two distinct components (Fig. 2). The fracture extended subgingivally (Fig. 3) and was associated with an extensive periodontal defect (8 mm) on the buccal surface (Fig. 4). The patient had a history of recurrent abscesses in this area following the completion of root-canal treatment. Treatment options offered to the patient included hemi-section and subsequent crowning, or extraction. The patient chose the latter option and the tooth was delivered completely. An incomplete vertical fracture was observed, extending from the crown on to the distal surface of the mesial root (Fig. 5).

Figure 1. Radiolucency suggestive of a fracture line in the furcation area of a root-filled mandibular first molar.

Radiolucency suggestive of a fracture line in the furcation area of a root-filled mandibular first molar

Figure 2. Fracture of the mandibular first molar extending along the margins of the intracoronal restoration.

Fracture of the mandibular first molar extending along the margins of the intracoronal restoration

Figure 3. The fracture extending subgingivally on the buccal surface.

The fracture extending subgingivally on the buccal surface

Figure 4. Detection of an 8-mm periodontal defect in the region of the fracture.

The fracture extending subgingivally on the buccal surface

Figure 5. Following extraction, an incomplete vertical fracture of the tooth extending from the crown on to the distal surface of the mesial root was evident.

Following extraction, an incomplete vertical fracture of the tooth extending from the crown on to the distal surface of the mesial root was evident


Discussion - References.
Discussion.
Complete or incomplete tooth fracture can arise in root-filled teeth unless adequate care is taken during preoperative assessment, during instrumentation and filling of the root-canal system, or in the design of the eventual coronal restoration. Whilst treatment is being performed, the root-canal system should be closely examined for evidence of any fracture. The operator needs to be aware of the risks of excessive removal of tooth substance during instrumentation and the exposure of such weakened teeth to mechanical forces during filling. Provision should be made for the tooth to be restored with adequate cuspal protection and mechanical strength immediately after completion of root-canal treatment, thereby preventing fracture initiation or propagation. Such restorations may take the form of a cast restoration, for example occlusal onlays, three-quarter crowns, or full-coverage crowns. The use of enamel-bonded and dentine-bonded composites (Wendt et al. 1987, Hansen & Asmussen 1990) or bonded amalgam restorations (Bearn et al. 1994) has been described. Root-filled teeth that have not been restored with an appropriate restoration have been shown to have a poor long-term prognosis (Ray & Trope 1995, Kirkevlang et al. 2000).

References.

Bearn DR, Saunders EM, Saunders WP (1994) The bonded amalgam restoration - a review of the literature and report of its use in the treatment of four cases of cracked-tooth syndrome: a clinical report. Quintessence International 25, 321-6.
Borelli P, Alibrandi P (1999) Unusual horizontal and vertical root fractures  of maxillary molars: an 11-year follow up. Journal of Endodontics 25, 136-9.
Cameron CE (1964) Cracked-tooth syndrome. Journal of the American Dental Association 68, 405-11.
Dang D, Walton R (1989) Vertical root fracture and root distortion: effect of spreader design. Journal of Endodontics 15, 294-301.
Hansen EK, Asmussen E (1990) In vivo fractures of endodontically treated posterior teeth restored with enamel-bonded resin. Endodontics and Dental Traumatology 6, 218-25.
Kirkevlang LL, Orstavik D, Horsted-Bindslev P, Wenzel A (2000) Periapical status and quality of root fillings and coronal restorations in a Danish population. International Endodontic Journal 33, 509-15.
Loewenstein WR, Rathkarnp R (1955) A study on the pressoreceptive sensibility of the tooth. Journal of Dental Research 34, 287-94.
McLean A (1998) Criteria for the predictably restorable endodontically treated tooth. Journal of the Canadian Dental Association 64, 652-61.
Morfis A (1990) Vertical root fractures. Oral Surgery, Oral Medicine and Oral Pathology 69, 631-5.
Pitts DL, Natkin E (1983) Diagnosis and treatment of vertical root fracture. Journal of Endodontics 9, 338-46.
Polson AM (1977) Periodontal destruction associated with vertical root fracture: eport of four cases. Journal of Periodontology 48, 27-32.
Randow K, Glanz PO (1986) On cantilever loading of vital and non-vital teeth in an experimental clinical study. Acta Odontologica Scandinavica 44, 271-7.
Ray HA, Trope M (1995) Periapical status of endodontically treated teeth in relation to the technical quality of the root filling and coronal restoration. International Endodontic Journal 28, 12-8.
Rosen H (1982) Cracked tooth syndrome. Journal of Prosthetic Dentistry 47, 36-43.
Shillingburg HT, Hobo S, Whitsett LD (1997) Fundamentals of Fixed Prosthodontics, 3rd edn. Chicago: Quintessence Publishing Co, Inc., p. 195.
Wendt SL Jr, Harris BM, Hunt TE (1987) Resistance to cusp fracture in endodontically treated teeth. Dental Materials 3, 232-5.