10/06/2026
As our patients retain their natural teeth for longer, and those teeth undergo more interventions in the “Restorative Cycle”, a feature we see more and more is Pulp Canal Obliteration (PCO).
PCO is a vital phenomenon, ie. requiring a vital pulp, in response to pulpal insult. This can be in the form of trauma (that solid, yellow, incisor that patients develop years after taking a knock), or more chronic pulpal irritation.
Increasing age, bruxism, or large, or repeated restorations all predispose to PCO.
While not a problem itself, PCO presents a challenge in the presence of apical periodontitis.
Secondary dentine is laid down throughout life, and tends to be ordered, while Tertiary dentine is generated in response to pulpal trauma. Tertiary dentine is quite disordered, and can contain islands of necrotic tissue.
When assessing any case, it is important to note the location and patency of the canals, and plan how you are going to find and negotiate them.
This 72-year-old gentleman was referred for treatment of his maxillary right first molar tooth (1.6).
The tooth had a crown in place, and had radiographic signs of apical periodontitis. It was just possible to trace the coronal portion of the MB canals, but nothing more.
Accessing through the crown revealed the pulp chamber to be completely calcified.
Krasner and Rankow’s 2004 paper, “Anatomy of the pulp chamber floor” is essential reading for anyone who carries out Root Canal Treatment.
Basic rules to follow include:
- The pulp chamber floor coincides with the level of the CEJ
- The Pulp chamber floor is dark grey
- The canal or***ces lie at the junction of the pulp chamber floor and walls.
Using these basic guidelines can keep you out of trouble.
Thankfully, I was able to locate the Palatal or***ce, and prepare the canal to Working Length. The Buccal or***ces were located in turn.
The canals were exceptionally hard to negotiate; especially the two MB canals. Essential aids to negotiation were:
- #8 C+ files
- #8 D-Finder files
- ToothSaver 14.03 rotary files
- 35% Trichloroacetic Acid (TCA)
Time and patience belong on this list as well.