Patient: 70 year-old female (at time of last recall exam, 40 years-old at time of initial treatment), excellent health to present.

Chief Complaint: Asymptomatic (1986), Swelling and Pain (1999), Slight Biting Sensitivity (2016)

Dental History: The patient presented to the author his first day of practice in Santa Barbara on 8/19/1986 with a recently prepared tooth (#15) for a full crown which had led to a pulp exposure.

Significant Findings (#15): All examination findings and clinical testing was within normal limits. The observed radiographic findings demonstrated a previously prepared crown with a deep base consistent with the reported exposure. The root appeared to have fused root anatomy with the close proximity of the buccal roots.

Pulp and Periradicular Diagnosis: Exposed vital pulp with normal periradicular support tissues (#15)

Treatment Prognosis: Good (#15)

Treatment Plan: Nonsurgical endodontic treatment (#15)

Special Considerations of Performed Treatment:

The treatment plan of nonsurgical endodontic treatment was routine and expected to provide the patient with a definitive successful treatment result. In 1986 the author had not yet incorporated the use of a microscope for dental procedures. Endodontic treatment was performed with the aid of a rubber dam isolating multiple teeth the distal #16 tooth clamped. #16 was subsequently extracted some time later and not noted to be present on any of the future recall examinations. Cleaning and shaping was performed and 3 canals were treated. An MB2 system was not observed. The patient was returned to her general dentist to place the core and finish the crown. A cotton pellet spacer and Cavit temporary filling was placed in the access cavity preparation.

Recall Exams and Follow-up:

On 3/19/1999 the patient returned with severe pain and swelling in the maxillary posterior left sextant. The buccal tissues overlying tooth #15 were sensitive to digital palpation pressure. She also demonstrated severe sensitivity to percussion. Recurrent endodontic pathosis with an acute alveolar abscess was diagnosis (#15). Incision and drainage was performed and a 7 day prescription of antibiotics prescribed (Clindamycin). There was no productive drainage of the from the I and D, so the root canal system was re-entered, the previous gutta percha removed and the tooth left open. 10 days later the patient returned and the root canal treatment was finished. She was asymptomatic. No root fracture was detected with the aid of a microscope and the presumption was that an MB2 canal system was missed. The retreatment focused on gaining deeper shape and more definitive debridement of the apical third of the roots. Although a wide groove was noted connecting the mesiobuccal orifice to the palatal orifice no “white dot” was found suggesting an MB2. It was judged to be imprudent to penetrate deep into the groove an risk perforation, but the better apical density of root filling material suggested that an improvement in apical debridement had been achieved and the author was satisfied with the result. A temporary filling was placed with a spacer in the access and she was sent back to her general dentist to place the final core and restoration.

On 2/18/2016 the patient was referred back to the author with the patient reporting discomfort in the #15 area again. The patient presented with subtle symptoms of biting sensitivity which her dentist referred her back for. There was some periodontal inflammation with a bleeding point (normal probing depth) at the distolingual area. A CBCT scan was taken and a periapical radiolucency was noted. The patient was the sister of an endodontist and highly motivated to save the tooth and avoid extraction. A long philosophical discussion ensued regarding the profound opportunity her case offered to show a 30 year long outcome series highlighting detailed documentation of technique changes with cause and effect. The 3D image revealed that the palatal and MB roots were fused with a wide enough isthmus to go deeper better addressing the wide fin with an ultrasonic file.

Interestingly the patient commented that the author should not have regarded the previous treatments as failures since the first one lasted 13 years and the second one 17 years. Her question: wasn’t this really a success? The author replied that it was simply a failure because bacteria was present in the untreated root canal system for 30 years. The conversation was directed toward what could reasonably be achieved to save the tooth now that was unable to be achieved in the past; i.e. the use of ultrasonics to definitively clean the deep isthmus area of the fused root with the aid of 3D CBCT mapping.

The attached pictures and video of the ultrasonic troughing highlight the first retreatment visit which was begun on 2/19/2016. When troughed 3mm apical to the pulp chamber floor a small file was able to be placed into the middle of the fin area which was similar to a deep MB2. The deep fused MB-P anatomy was debrided for the first time in 30 years.

Key Learning Points:

1. The advent of the microscope and CBCT 3D imaging has profoundly changed endodontic treatment so that deep root anatomy can be mapped and successfully debrided.

2. The use of ultrasonic files allows clearing of complex isthmuses within the root that would be otherwise over-enlarged with rotary instrumentation.

3. Detailed documentation and long term recall evaluation is an extraordinary opportunity to assess one’s own technique changes over time.

4. This authors key technique changes proposed to improve the outcome: definitive debridement of the complex fused root canal system anatomy, immediate aseptic sealing core placement after obturation, two step treatment after established aseptic closure with validated healing, and deep temporary placement without a spacer during the inter-appointment period.