Non-surgical Root Canal Treatment Case V: Mandibular Premolar

Non-surgical Root Canal Treatment Case V:
Mandibular Premolar

Takashi Okiji


Chief Complaint

“My lower right jaw was swollen and painful and I had the affected part operated on by a surgeon. Now the pain and swelling are almost gone, but I still feel numbness in my lower lip.”

Medical History

The patient (Pt) was a 71-year-old female. Medical history was not significant, except for hypertension that was controlled with a calcium channel blocker. The Pt had no known drug allergies (NKDA).

The Pt was considered American Society of Anesthesiologists Physical Status Scale (ASA) Class II.

Dental History

Pt had been referred by an oral surgeon for the endodontic treatment of tooth #29. Approximately one month previously, the Pt had been referred to the oral surgeon by a general dentist for the treatment (Tx) of severe spontaneous pain and swelling of the right mandible associated with a loss of sensitivity on the right side of the skin and mucosa of her lower lip. The general dentist made an opening in the pulp chamber, which was left unsealed. The oral surgeon made an incision in the fluctuant swelling under a diagnosis of an acute apical abscess originating in tooth #29, and prescribed a cephem antibiotic (Flomox®). The Pt’s swelling and pain disappeared after a few days. However, the numbness was still present 14 days after the first visit and the Pt was given a prescription for vitamin B12 for the management of paresthesia. Then the oral surgeon referred the Pt to the Department of Endodontics for endodontic Tx of tooth #29.

Clinical Evaluation (Diagnostic Procedures)


Extra-oral Examination (EOE)

No swelling or lymphadenopathy of the submandibular and neck areas was found. Soft tissue sensitivity, as evaluated with a dental probe, revealed a reduced tactile sensitivity in the skin of the right mental region and lower lip.

Intra-oral Examination (IOE)

Reduction of tactile sensation in the oral mucosa up to the midline was recognized. The oral hygiene of the Pt was poor. Tooth #29 had an unsealed access cavity on its occlusal surface and an old composite filling on its buccal (B) cervical area (Figure 11.1). There were carious lesions on its mesial (M), lingual (L), and distal (D) cervical surfaces close to the gingival margin. The probing pocket depths were 3–4 mm around the circumference of the tooth.

Photograph showing tooth #29.

Figure 11.1 Preoperative clinical photograph of tooth #29.

Diagnostic Tests

Tooth #31 #29 #28
Percussion +
Palpation +
Cold + +
EPT + +

EPT: Electric pulp test; +: Response to percussion or palpation, and normal response to cold and EPT; -: No response to percussion, palpation, cold, or EPT

Radiographic Findings

Periapical (PA) radiograph revealed that tooth #29 had a single root and root canal that was curved at the apical one-fourth to the D at approximately 30° (Figure 11.2). There was a radiolucency approximately 5 mm in diameter at the PA area of tooth #29. At the M cervical region, there was a deep carious lesion showing close proximity to the pulp chamber. The right premolar area on the panoramic radiograph showed distortion, but it was suggested that the periapical radiolucency (PARL) was in close proximity to the mental foramen (Figure 11.3). Computerized tomography (CT) scans demonstrated that the B cortical plate of the apical region of tooth #29 was interrupted, and the PARL involving tooth #29 showed communication with the mandibular canal (Figure 11.4, 11.4).

Illustration of Preoperative periapical radiograph of tooth #29.

Figure 11.2 Preoperative periapical radiograph of tooth #29.

Illustration of mandibular right premolar and molar regions.

Figure 11.3 Preoperative panoramic radiograph showing mandibular right premolar and molar regions.

Illustration of Preoperative multi-slice CT images of tooth #29: Coronal view.; Illustration of Preoperative multi-slice CT images of tooth #29: sagittal view.

Figure 11.4 Preoperative multi-slice CT images of tooth #29. Coronal view (A) and sagittal view (B). The B cortical plate of the apical region of the tooth #29 is interrupted, and the PARL involving tooth #29 shows communication with the mandibular canal.

Pretreatment Diagnosis


Pulp Necrosis, tooth #29


Symptomatic Apical Periodontitis, tooth #29

(Associated with Mental Nerve Paresthesia)

Treatment Plan


Emergency:No treatment

Definitive:Non-Surgical Endodontic Treatment


No treatment


Cast metal post and core, and a full metal crown


Favorable Questionable Unfavorable

Since there was a possibility that extraction of tooth #29 would exacerbate the paresthesia of the mental region, and the tooth was deemed to be restorable, non-surgical endodontic Tx was planned to control PA inflammation, with an expectation of subsequent resolution of mental nerve paresthesia.

Clinical Procedures: Treatment Record

First visit (Day 1): The caries of the proximal and L cervical regions was first removed with low-speed round burs and excavators, and the cavities were temporarily sealed with a temporary filling material (Caviton®, GC Corporation, Tokyo, Japan). The tooth was then isolated with a rubber dam (RD). The access cavity was slightly enlarged using a diamond bur with a high-speed handpiece, and the coronal pulp chamber was irrigated with approximately 1.5% sodium hypochlorite (NaOCl) (Neo Cleaner, Neo Dental, Tokyo, Japan), diluted with sterile saline. Approximately, the coronal one-third of the canal was then flared with Gates-Glidden drills (#2 to #4 in a step-back manner), and again irrigated with NaOCl. Instrumentation of the canal was performed by a modified crown-down pressureless technique using stainless steel K-files (Mani, Tochigi, Japan) and nickel titanium (NiTi) rotary instruments (K3™, Sybron, Orange, CA, USA), rotated at 300 rpm using a torque-control motor (TCM Endo, Nouvag, Goldach, Switzerland). The canal was first instrumented with K-files of progressively smaller sizes (#35 to #20). The files were inserted into the canal and rotated passively at the length of resistance. A provisional working length (WL) of approximately 3 mm short of the apex was determined. Then, K3 instruments (size#/ taper) #45/.04, #40/.04, #35/.04, and #30/.04 were used sequentially in a crown-down manner until the #35/.04 instrument reached to the provisional WL. The canal was irrigated with NaOCl at every file change. Following preparation to the provisional WL, passive ultrasonic irrigation was performed to activate NaOCl using an ultrasonic device (ENAC, Osada, Tokyo, Japan) and a size #20 ultrasonic file (Osada, Tokyo, Japan). Final WL was then determined with an electronic apex locator (Root ZX® II, J.Morita, Kyoto, Japan) and a size #10 K-file. Following glide path preparation with a size #15 K-file, the canal was again instrumented with K3 instruments (size/ taper, #35/.04, #30/.04, and #25/.04) in a crown-down manner until the size #25/.04 taper instrument reached the working length. The canal was irrigated with NaOCl after each file change. The root canal was dried with paper points, dressed with calcium hydroxide (Ca(OH)2) paste (Calcipex®, Nippon Shika Yakuhin, Shimonoseki, Japan), and the tooth was provisionally sealed with Caviton®.

Second visit (Day 10): The Tx at the first visit was uneventful, and the paresthetic symptoms were resolving with a slightly reduced sensation of the affected area. The tooth was isolated with an RD, the temporary restoration in the access cavity was removed, and the Ca(OH)2 dressing was removed with K-files and irrigation with a syringe and an ultrasonic device using NaOCl as an irrigant. The canal was then instrumented to a size #35/.04 taper with K3 instruments in a crown-down manner. Subsequently, the root canal was dried with paper points and filled with gutta-percha (GP) points (GC Corporation, Tokyo, Japan) and a zinc oxide non-eugenol sealer (Canals®-N, Showa Yakuhin Kako, Tokyo, Japan) using a lateral condensation method. The access cavity was sealed with Caviton®. The Pt did not undergo a radiograph at this appointment since she had to leave urgently.

Working length, apical size, and obturation technique

Canal Working Length Apical Size, Taper Obturation Materials and Techniques
Single 19.0 mm 35, .04 Zinc oxide non-eugenol sealer,
Lateral condensation

Post-Treatment Evaluation

Third visit (2-month follow-up): The Pt returned and reported that tooth #29 was free from symptoms. The numbness on the mental area had resolved and the tooth showed no tenderness to percussion, palpation, or biting, although the temporary restoration of the cervical area had been lost. PA radiography revealed that the root canal filling of tooth #29 was acceptable and the PARL of this tooth was reduced in size, although the cervical carious lesion had expanded (Figure 11.5). The tooth was scheduled for permanent restoration.

Illustration of radiograph showing root canal filling of tooth #29.

Figure 11.5 Two months after root canal filling of tooth #29.

Fourth visit (15-month follow-up): At the postoperative (PO) evaluation, the Pt was asymptomatic and the tooth had been restored with a cast metal post and core, and a full metal crown. There was no tenderness to percussion, palpation, or biting. Radiographic examination revealed that tooth #29 showed a complete resolution of PARL (Figure 11.6, 11.6).

Illustration of periapical radiograph showing tooth #29.; Illustration of panoramic radiograph showing tooth #29.

Figure 11.6 Fifteen-month follow-up of tooth #29. Periapical (A) and panoramic (B) radiographs. Tooth #29 shows a complete resolution of PARL.

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Jan 14, 2018 | Posted by in Endodontics | Comments Off on Non-surgical Root Canal Treatment Case V: Mandibular Premolar
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