Step 6: Quality Criteria After Obturation

Prepared and filled canals should demonstrate a homogenous radiopaque appearance, free of voids and importantly filled to working length. The fill should approximate canal walls and extend as much as possible into canal irregularities such as an isthmus or a C-shaped canal system. The fill of accessory canals is not predictable and not per se a prerequisite for success [76]. However, in molar cases with larger accessory spaces, in addition to the main canals, procedures such as the ones described in this chapter typically result in debridement and often radiographically visible fill (see Figs. 6.1, 6.4 and 6.10).

In order to avoid overextension of root filling material into the periapical tissue, specifically in the mandibular canal, it is recommended to accurately determine working length to prevent destruction of the apical constriction. For infected root canal systems, the best healing results are achieved when the working length is between 0 and 0.5 mm from the tip of the root as visible on a radiograph [1, 2].

In molar endodontics, determination of apical canal anatomy is often difficult. It may be appropriate for second mandibular molars that are in close proximity to the mandibular canal to deemphasize patency and even block apical foramina to avoid large overfills (Fig. 6.17). Large overfills may be an impediment to healing and in the worst case may be associated with nerve damage.

In general, undesirable and uncorrectable outcomes of molar root canal treatment, identifiable on the final radiograph, include:

• 1. Excessive dentin removal during access and instrumentation
• 2. Overt preparation error such as perforation, ledge formation, and apical zipping
• 3. Presence of an instrument fragment in not fully disinfected canals
• 4. Overfill and overextension

Fig. 6.1 7 Examples of molar root canal treatment that resulted in significant overfill. Such a condition can result in permanent damage when sealer is placed close to the infraalveolar nerve. All cases shown resulted in paresthesia (Courtesy of Dr. A. Gluskin)

Each of these outcomes must be documented and the patient notified as they may reduce the odds for a successful outcome. In cases such as par- or dysesthesia after an overfill, immediate attention and possibly referral is indicated.