4.8
Obturation of the Root Canal 1
Kreena Patel
Objectives
At the end of this case, the reader should appreciate the importance of root canal obturation and understand the different materials available and methods of obturation.
Introduction
A 45‐year‐old male patient presented with pain associated with the upper right first molar (UR6). The tooth had been restored with a composite restoration three years ago.
Chief Complaint
An intermittent, dull, throbbing pain was localised to the UR6. The patient was struggling to eat on the right side of his mouth.
Medical History
Unremarkable.
Dental History
The patient was a regular attender at the dentist.
Clinical Examination
Extraoral examination was unremarkable. Intraoral examination revealed a swelling on the buccal mucosa associated with the UR6 (Figure 4.8.1).
The UR6 was restored with mesio‐occlusal composite restoration and with recurrent caries. The tooth was tender on percussion and biting. Periodontal probing depths were 1–3 mm and the tooth did not respond to pulp tests.
What did the periapical radiograph reveal?
- Alveolar bone height within normal limits.
- Marginal defect and caries under the mesial aspect of the composite restoration.
- Calcifications in the pulp chamber.
- The distal and palatal roots have visible root canals; the mesial root has a 30° distal curvature with indistinct canal path.
- Periapical radiolucencies were associated with the apices of the mesial, distal and palatal roots.
- Mesial radiolucency on the UR7 requiring further investigation with a bitewing radiograph (Figure 4.8.2).
Diagnosis and Treatment Planning
What is the diagnosis?
Pulpal necrosis with symptomatic apical periodontitis with sinus suppuration was the diagnosis for tooth UR6.
What are the treatment options for tooth UR6?
- Non‐surgical root canal treatment, subject to restorability.
- Extraction.
- No treatment.
The patient was keen to save tooth UR6 and opted to proceed with root canal treatment. The existing restoration and caries were removed. The tooth was found to be restorable and a composite pre‐endodontic restoration was placed.
Dental dam isolation and access were carried out. The calcifications in the pulp chamber were removed using a piezo‐electric endodontic ultrasonic tip. Four canals were located (palatal, disto‐buccal, first mesio‐buccal and second mesio‐buccal) and prepared using hand and rotary files. Sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA) were used to disinfect the root canal system.
The master cone gutta percha (GP) points were tried into the canals and checked for apical tugback. It is important to leave fluid in the canal when trying in the master cone because it mimics the lubricant effect of the sealer and aids in the seating of the cone.
A post‐obturation radiograph was taken (Figure 4.8.3).
What is the purpose of obturating the root canal system?
Obturation aims to three‐dimensionally seal the root canal system. The purpose is to:
- Prevent microorganisms entering the root canal system and causing reinfection (coronal seal).
- Prevent tissue fluids entering the root canal system and providing nutrients for any remaining microorganisms (apical seal).
- Entomb any remaining microorganisms and their by‐products and prevent their spread through the apex.
What are the ideal properties of a root canal filling material?
- Dimensionally stable
- Non‐irritant, ideally biocompatible
- Antimicrobial
- Radiopaque
- Does not discolour tooth structure
- Sterile
- Easily manipulated to conform to the shape of different canals
- Insoluble
- Good handling and working time
- Easily removed if necessary
What are the constituents of gutta percha cones?
65% zinc oxide, 20% GP, 10% radiopacifiers, 5% plasticisers.
GP exists in two crystalline forms (α and β). Processed GP cones normally exist in the β‐phase, where they are a solid structure that can be compacted. When the material is heated it transitions to the α‐phase, which is tackier and more pliable. Cooling of the α‐phase back to the β‐phase results in shrinkage.
What are the advantages and disadvantages of using gutta percha as an obturation material?
See Table 4.8.1.
How should gutta percha cones be disinfected prior to obturation?
Ideally, GP cones should be disinfected by submerging them in sodium hypochlorite solution for one minute and drying prior to use.
What is the purpose of a root canal sealer?
Sealers adhere to dentine and fill the irregularities between the core filling material and the canal walls. Sealers can also flow into lateral and accessory canals. It also acts as a lubricant during the obturation procedure.
Table 4.8.1 Advantages and disadvantages of gutta percha as an obturation material.
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