The Dangerous Curved Root

Terry Pannkuk, DDS, MScD Clinical Endodontic Technique Instruction, Cleaning and Shaping

Patient: 57 year-old female with controlled Type 2 Diabetes

Chief Complaint: Patient complained of a constant throbbing toothache in the lower right posterior jaw. She reported 5/10 pain level and presented for emergency treatment

Dental History: A lithium disilicate crown had been placed on the lower right first molar (tooth #30) several years earlier. Pain developed the previous few days.

Significant Findings (#30): Clinical examination normal periodontal probing depths. Percussion elicited severe sensitivity with slight biting and chewing sensitivity. Radiographic examination revealed long curved roots with the mesial root being unusually narrow in diameter at mid-root. Thermal stimulation with heat resulted in a sharp transient response and cold stimulation resulted in a very sharp lingering throb reproducing the patient’s symptoms.

Pulp and Periradicular Diagnosis (#30): early stage acute irreversible pulpitis (possible cracked tooth) with an acute periradicular periodontitis

Treatment Prognosis: Excellent (#30)

Treatment Plan: Nonsurgical endodontic treatment (#30)

Special Considerations of Performed Treatment:

Management of long curved narrow roots warrants extreme caution during cleaning and shaping. Over-flaring can lead to strip perforation of the furcation side root concavity. Perforation can be avoided by very fine acute tactile awareness with light pressure applied to files. 90% trichloroacetic acid used early in the canal debridement process, dehydrates the pulp, facilitates NaOCl tissue digestion and efficiently clears calcified debris (dentin chips) generated during instrumentation.

In a root like this constant clearing of debris is critical to avoid blockage and ledges that would lead to obstruction of patency and perforation. As roots are shaped toward the peripheral cementum surface the dentin becomes noticeably hard and more difficult to file. This is the sign to stop flaring and accept the taper the root anatomy allows.

First treatment visit (4/20/2021):

The patient had very limited jaw opening so she was premedicated with 1mg of Xanax. The length of time and incremental cleaning and shaping on this case warranted two visits. Length measurements and apical patency was established in all canals the first visit. Calcium hydroxide was place and a Cavit temporary filling without a spacer.

Second treatment visit (4/28/2021):

The temporary filling was removed and the calcium hydroxide removed with additional 90% TCA and the EndoActivator. Cone fitting required narrower gutta percha cones due to the narrow root diameter and length. Medium-Fine non-standardized cones were fit with a .20 apical size. The MB cone joined the ML cone with was fit to length. Final cleaning and shaping was performed and the entire root canal system was filled with gutta percha and Kerr Sealer via the vertical compaction of warmed gutta percha technique.

A final core was placed as follows: Excess gutta percha and sealer removal with chloroform, drying with alcohol and microetching with 50 micron particles, Photobond and Luxacore incrementally placed, cut back from the occlusal surface, porcelain etch, silane, Optibond FL and layered Filtek Ultra Supreme to reproduce esthetic surface.

Key Learning Points:

  1. Long narrow curved roots should be identified at the initial exam before root canal treatment. Well angulated radiographs are extremely important. Straight, Slight Mesial Angle, and Bitewing radiographs should be taken for lower molars.

  2. Activated 90% TCA prevents tissue and debris blockage facilitating apical patency

  3. Very light file pressure should be applied to prevent strip perforation on narrow concave roots. Tactile awareness of dentin hardness signals when to stop flaring.

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