The clinical case pictured in Figure 1 was recently referred to me. A significant cervical perforation had occurred during the access one-week prior, and the location of the perforation made either intra-coronal repair or surgical correction problematic.
While much could be written about perforations, several important lessons can be drawn from this that have clinical application. The radiograph in Figure 1 is a vivid reminder of the importance of proper pre-operative treatment planning, enhanced visualisation during access and having the correct burs and experience in canal location. Avoidance of the cervical perforation that ensued could have set the stage for an excellent endodontic result instead of being the precursor to an artificial implant as this patient opted for extraction (after beingpresented with all the options).
The referring doctor communicated that the patient was ‘restless’. If the patient was not cooperative during access in any way, this alone was a reason for referral.
Digital radiography is a great help in one area of gathering pre-operative information in assessing the risk factors present. The author is a strong advocate of the DEXIS digital system (DEXIS digital radiography, Alpharetta, GA, USA) for its clarity of image, solid software platform and ease of use.
Multiple images of the tooth taken from different angles pre-operatively can go a long way towards determining anatomical nuances that can require special attention. The canal spaces in this lower molar are small, calcified and would likely have challenged even the best clinicians.
To avoid such misadventures, several additional considerations should be observed. Firstly, visualisation during access should ideally be through an enhanced source of lighting and magnification like loupes or a surgical operating microscope such as the Global microscope (Global Surgical, St. Louis, MO, USA). Lighting and magnification could have prevented this mishap.
Second, the doctor did not use the correct motion for uncovering the canals. The rounded nature of the access implies that a large round bur was used in a horizontal manner once the doctor thought they were on the chamber floor, not apically in the direction of the canal orifices. In essence, the motion of bur use was incorrect and the dentin removal misaligned with the orifice location. Both of these factors were compounded by the lack of visualisation. Once difficulty was encountered in the location of the orifices, a radiograph should have been exposed.
An ideal system to give the clinician all the burs needed to handle virtually any access would be the LA Axxess kit (SybronEndo, Orange, CA, USA). This gives the clinician several sizes of long shank round bur as well as a trans metal bur amongst others. While a comprehensive discussion of the LA Axxess kit is beyond the scope of this column, virtually all access preparations and build-ups can be made with its contents – it is essentially universal.
While not pictured, the coronal access made was far too small and resembled a ‘BB shot’. In other words, it was relatively small and to the mesial of the occlusal surface. The initial penetration into the dentin was incorrect and the location of the pulp chamber was made far more difficult. As a rule of thumb, starting at the centre of the tooth is usually most productive and, once the chamber is located, a straight-line access can be created from that point forward.
Finally, once the perforation occurred, it had value to make an immediate referral. Had the patient opted for treatment, early intervention to repair the perforation is correlated with enhanced healing.
In summary, adequate risk assessment, taking multiple-angled radiographs before treatment, having the needed burs and visualisation during access as well stopping to take additional radiographs if the canals are not found as expected, can all help avoid iatrogenic events such as the one pictured.
Quick Tips
• Pre-operative treatment planning is essential
• Digital radiography is a great help in assessing potential risk factors
• Visualisation should be through an enhanced source of lighting and magnification
• Start at the centre of the tooth when penetrating into the dentin
• Stop to take additional radiographs if the canals are not found as expected.
