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The Fractured Root-Crown Algorithm: When to Extract?

Terry Pannkuk, DDS, MScDInstructional, Fractured Roots, Sample Cases, All by Date

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Clinical view of a crack stained with caries

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A crack line showing expanded width compared to adjacent natural grooves

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Transillumination with a fiberoptic will reveal fracture extending into dentin having the fractured portion of the crown opposite the light remain dark

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Fiberoptic light showing a fractured distolingual cusp

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Crown removal revealed hidden pin-ups, recurrent caries, and a root fracture with associated periodontal defects

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An old corroded amalgam showing a large marginal gap in the box area an a crack through the unrestored marginal ridge

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Endodontic access is frequently necessary to discover a crack extending through the pulp chamber floor having a poor prognosis

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Endodontic access with completed cleaning and shaping shows a crown limited fracture undermining the mesiobuccal cusp

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Irrigation with alcohol and drying can frost debris harboring in the crack helping to determine its extent

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The same tooth in the previous figure cleared with EDTA additionally aiding to determine the apical extent of a crack

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Cracks of maxillary first molars quite frequently course to the MB2 orifice area

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Cracks are often associated with teeth having previous posts

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A CBCT scan showing a crescent-shaped radiolucency of the periodontal ligament space often represents a root fracture especially with additional corroborative findings

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Extracted tooth showing an incomplete crown root fracture extending half-way down the root

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In this series a zirconium crown was accessed to reveal a comminuted crown fracture (A)

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Deeper endodontic access eliminated the superficial crown fracture with one deep crack line remaining (B)

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Completed endodontic access and cleaning and shaping of all canals demonstrated that the remaining crack extended a couple millimeters into the distolingual orifice (C)

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Microtroughing with an ultrasonic file eliminated the apical extension of the crack making it less likely to be invaded with caries and propagate (D)

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Troughed incomplete crown-root fracture (E)

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Fracture Decision Tree

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Fractured teeth present a diagnostic and treatment planning dilemma

The following is a proposed algorithm/decision tree for assessment, diagnosis, prognosis determination, and treatment planning:

A crack presentation on a virgin tooth can be clinically inspected (no coronal coverage or box restorations preventing visible inspection),

A. The fiberoptic transillumination-light transmits across fracture plane, then
likely a craze line not extending significantly into crown dentin:monitor no treatment

or

B. The fiberoptic light beam breaks at crack line (dark on crown opposite suspected crack line), then minimum tx: protect occlusion (adjustment) and proceed to endo testing

Clinical and Vitality testing

  1. If within normal limits (pressure tests: percussion, biting, chewing, thermal tests), then protect occlusion and monitor only, or

  2. There exists sharp cold sensitivity and/or sensitivity upon pressure tests, especially pain upon release of biting or chewing pressure, then proceed with full-cuspal protection crown prep (no sharp angles ( ¾ gold crowns are unacceptable and not very protective, full gold ideal with long-term supportive evidence, zirconium possible option but no long-term evidence)

After Crack Preparation and Assessment of Extension

Note the extent of the crack into dentin (ideally with a microscope, loupes are inadequate) and microprepare the crack on the occlusal surface within the outline of an ideal endo access prep, then

  1. If the crack is eliminated by a relatively shallow micropreparation, then provisionalize and monitor for a month, then
    a. If the tooth remains asymptomatic and vital: proceed with final restorative plan, or
    b. If the tooth develops symptoms (ache, sharp cold sensitivity, especially heat, pressure sensitivity, then schedule for endodontic treatment before restorative work

,or

  1. If the crack is virtually certain to enter the pulp or tertiary dentin and/or calcific pulp degeneration with radiographic advancement notably more significant than adjacent teeth (i.e. not physiologic aging), then perform endodontic access with further crack exploration, or

Exploratory Endo Access

A. Crack crown-limited (supragingival level), then finish endodontic treatment , core, and restorative plan (a favorable prognosis is expected if restored with an ideal fracture resistance design; i.e full cuspal coverage/no sharp angles)

B. Crack crown-limited (subgingival, but not subosseous level), then inform patient of guarded-to-fair long term prognosis and risks of future crack propagation, next proceed with their informed consent, and internally microprepare the crack with a bonded core (ideally sandblasted clean to improve bonding) Some new evidence suggests bioceramics and Biodentine (tricalcium silicate materials) have favorable strength properties and flow for certain situations. A goal is to minimize the chance of caries developing within the crack interface and weakening the tooth predisposing it to crack propagation

C. Crack extends 1-3mm into root dentin (below pulp chamber floor into the orifice), then inform patient of a guarded prognosis and that treatment is heroic (the tooth must have high strategic value for retention with the implant option being judged less favorable), and with the patient’s consent proceed with endodontic treatment and the restorative follow-up plan ( an ideal fracture resistant restoration is essential, likely full gold crown)

D. Crack extends deep into the root dentin beyond 3 mm, then extract tooth

For years dentists have wrestled with a protocol for treating cracked teeth. Some caveats, or exceptions to these guidelines exist and validating high level science is scant. Patients with parafunction/bruxism are more likely to require extraction. If a crack is limited to the distal surface of the most distal tooth one can consider being more heroic in a treatment attempt (eg. a crack through the distal marginal ridge of a lower second molar because a minor angular periodontal defect on the distal is not going to compromise an adjacent tooth that does not exist).

There are many shades of gray and cases where the decision simply rests with the temperament of the patient to accept uncertainty and their need to retain the tooth for an intermediate period of time in their life.

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