Dens evaginatus (a.k.a. Leong’s premolar) is an odontogenic developmental anomaly. This anomaly, an enamel-covered tubercle with an extension of pulp horn in most cases, occurs primarily in premolars. Loss of this tuberculated cusp during natural root maturation and development will result in early pulp exposure, pulpal necrosis, periapical disease, and arrested root development. Early diagnosis and management of dens evaginatus is therefore the key factor in preventing premature loss of tooth vitality.
Category Archives: Endodontic Treatment
When deciding on an endodontic-restorative plan for a tooth, one should always keep in mind the age of the dental pulp (i.e. patient’s age). Younger dental pulp = more cellular, vascular, defensive and therefore resilient. This fact can help us decide on a more appropriate and conservative treatment for a tooth when facing pulp exposure as a result of trauma or caries excavation.
Vital Pulp Therapy (VPT) techniques is attempted in order to remove the reversible pulpal injury, to preserve the vitality of the pulp and to ultimately allow continued root/tooth growth. The technique comprises: a) good isolation, b) complete caries removal, c) disinfection of the access cavity with NaOCl, d) stopping the bleeding with a moist cotton pellet, e) applying pulp capping material such as ProRoot® MTA or Biodentine™, and f) restoring the access cavity with permanent restoration after confirming the setting of the capping material.
In the above case Direct Pulp Capping with MTA, irrespective of the size of carious exposure, was performed because this 13 year-old patient presented with non-lingering, non-spontaneous and reversible pulpitis symptoms. In addition, carious exposure resulted in fresh bleeding from pulp horns that could be stopped with applying moist cotton pellet. If a patient presents with irreversible pulpitis symptoms, other VPT techniques should be considered.
The only non-precious stone that I know is the pulp stone. One of the factors contributing to root canal failure is remaining infected pulp tissue and the pulp stones, if left behind unnoticed, are the main reason for trapping tissue and retaining infection. Pulp stone removal is therefore a crucial factor in achieving a successful result in endodontic treatment. The following case shows how a large pulp stone can result in failure of a reasonably well done root canal treatment by trapping infected tissue, hiding the MB2 canal and retaining infection.
Proper access cavity (i.e. adequately large and at the level of the CEJ) in order to visualize the outline of the pulp stone/chamber floor is the key in removing it completely. In the above example the pulp stone is easily dislodged by troughing around it using a large diamond-coated ultrasonic tip and applying the energy directly to the calcified tissue. For demonstration and documentation purposes, no water was used in this case; however, it is highly recommended to use water for its cooling effect and in order to facilitate the debris removal.
If you attended my lecture at the Pacific Dental Conference last month, I mentioned “The Laws” that allow us to safely and predictably locate canals without being worried about mishaps (i.e. perforations, over-enlarged access cavities, etc.). One of the scenarios that we have to always be prepared for is accessing through a crown that is placed on a rotated tooth. One of the key elements discussed was the use of a probe to gain a better appreciation of the root outline at the CEJ level. The “Law of Concentricity” then allows us to start our access cavity preparation in the right direction.
The case below shows a rotated tooth #1-4 under a PFM crown. Preparing a typical access cavity in the Buccal-Lingual direction would definitely result in mishaps. Understanding the orientation of the tooth prior to the start of root canal treatment can result in achieving a safe and a conservative access prep. Note that even the rubber dam clamp wings are not good guides for the orientation of the chamber floor and for locating canals.
Heavy bite, specially with less than ideal occlusion or cusp-fossa relationship, can result in cracks and fractures in teeth. Here is an example of a case with heavy occlusal pressure concentrated on the lingual inclinations of the buccal and lingual cusps of tooth #2-4. Two mesial enamel cracks are evident in this case.
Lets imagine the following scenario if we do nothing for this asymptomatic tooth:
With time, the cracks propagate and involve the pulp chamber. Based on the position of the existing restoration, a tooth split may result no matter how innocent (don’t blame the amalgam fillings). Clinical symptoms (pulpitis) appear. Root canal is done and the initial sensitivity symptoms do resolve. A crown is then fabricated for a possibly deeply cracked tooth. The biting tenderness however persists post-endodontic treatment. If the patient is lucky not to go through further unnecessary treatments (i.e. retreatment, apical surgery, etc.), the tooth will eventually be replaced with an implant. And, this is one of the reasons why root canals get their poor reputation. “Root canals don’t work”, “every root canaled tooth fractures”, or the most insulting to my profession that I have ever heard: “root canaled tooth is an eventual space maintainer for an implant.”
So, lets contemplate the above scenario and think about prevention and saving teeth instead.
Sometimes when the conventional endodontic access is not possible, the unconventional approach can save the day.
A clinician should always aim at establishing a straight line access (SLA) in order to properly instrument, irrigate and obturate the canal system. Depending on the initial challenges, establishing a SLA could mean accessing an anterior tooth through its buccal surface [example below], accessing an anterior tooth through its incisal edge, or accessing a molar tooth through its mesial marginal ridge or its MB cusp.
Imagine the following scenario:
A busy day in practice! A patient comes in with tooth #2-6 (upper left first maxillary molar) being extremely sensitive to cold (a.k.a. a “hot tooth”). You notice a very old, large amalgam filling on the tooth which had been done over 2o years ago. No recent restorative changes in the area is reported by the patient. Breathing in air, blowing air on this tooth with an air-water syringe or applying ice to the tooth sends the patient through the roof. All other teeth in this quadrant are responding normally to cold test. Quickly and confidently, a pulpal diagnosis is reached (irreversible pulpitis), endodontic treatment is recommended, and the need for a full coverage crown is also emphasized after root canal treatment. Simple, right?
Well, not so fast!
- unless you stopped and thought about the reasons why the tooth became sensitive to begin with (i.e. thinking about the etiology for pulpitis and the possible pathways to the pulp),
- unless you thoroughly examined the tooth clinically and looked for signs of cracks, leakage, caries, periodontal disease, parafunctional habits, etc.,
- unless you grabbed a perio probe and actually noticed a 6-7mm probing defect on the distal aspect of the tooth,
- unless you noticed on the pre-op radiograph a questionable area with respect to the quality of the crestal bone between teeth #2-6 and #2-7,
- unless you removed the obscuring filling and gave yourself an adequate view of what lies beneath during the treatment (as opposed to those who still love to brag about their super conservative access and their beautiful final result through a tiny 2x2mm hole),
You may miss a more serious issue with this innocent-looking tooth in need of JUST a root canal and a crown, you may lose the opportunity to properly inform your patient of possible outcomes of your treatment and you may end up performing unnecessary treatments for a tooth with no hope.
Just imagine the final conversation with the patient after a quick exploratory/pulpectomy procedure:
Me – “Ms. Black, unfortunately your tooth cannot be saved as I had suspected and warned you before we started the root canal procedure today.”
Ms. Black – “I am amazed Dr. E! [with a smile] You knew exactly what was wrong with my tooth. You called it.”
As if dealing with MB2 canals in upper molars was not complicated enough (see my previous post on MB2 canals), here is another thing to consider when doing root canals on lower molars:
The presence of an independent Middle Mesial (MM) canal has been reported for decades in endodontic literature. Owing it to technological advancements, it appears that the incidence rate for these extra canals is on the rise: Skidmore & Bjorndol 1971 (0%), Pineda & Kuttler 1972 (0%), Vertucci 1984 (1%), Fabra-Campos 1989 (2.6%), Goel et al. 1991 (15%). I even hear incidence rate of up to 60% based on the more recent micro-CT studies. This may be pushing it though!
It is really important to realize that MM canal could exist and therefore, the area between MB and ML canals in lower molars should be explored thoroughly during accessing, locating canals and instrumenting.