It is known that micro-organisms in irregular spaces beside the main canals and specially in lateral and accessory canals survive the limited effect of chemomechanical instrumentation. There are overwhelming amount of evidence in endodontic literature in support of the short-term use of CaOH (a week or longer). It effectively reduces or eliminates bacterial infection from the root canal system. Therefore, it is always beneficial to use an inter-appointment medicament such as calcium hydroxide, specially in non-vital or re-treatment cases.
CaOH is usually made into a paste by mixing with saline. Inside the root canal system, CaOH dissociates into Ca++ and OH- ions resulting in an increased pH (up to 12.5) and an alkaline environment. No micro-organisms survive at this pH and when they come into direct contact with CaOH.
The beneficial effects of CaOH include:
- Prolonged and broad antibacterial action
- Anti-inflammatory action (for example, stopping the exudative stage of inflammation)
- Helping the local immune system
- Enhancing the necrotic tissue dissolution when using in conjunction with NaOCl
- Promoting bone formation and repair (complete repair is expected in 2-3 months)
- Preventing re-infection inside the canal system by virtue of its physical presence
My favourite preparation of calcium hydroxide is UltraCal® XS. UltraCal® XS is an aqueous, 12.5 pH, syringeable, radiopaque, calcium hydroxide paste. Flexible NaviTips are used to deliver CaOH inside the canals. NaviTips are not side-vented needles. So, care should be taken while placing CaOH suing this delivery method. It should be delivered short of the apex (use the rubber stopper as a guide) while slowly withdrawing tips.
The dentin mud or “smear layer” forms as a result of the action of endodontic instruments during root canal therapy. The debris (inorganic materials along with the pulpal tissues, bacteria, blood cells, etc.) that is formed is smeared against the canal surface during the cutting and planing actions of the endodontic files and instruments. This layer harbors surviving micro-organisms and interferes with the penetration of irrigation solutions, medication and obturation materials into the dentinal tubules.
Removal of this layer not only allows the irrigants to better penetrate and kill the micro-organisms that have invaded the dentinal tubules, but it also improves the contact and adaptability between the obturation material and the canal walls and ultimately the seal.
The most commonly used endodontic irrigants are: sodium hypochlorite (NaOCl) and EDTA. They effectively remove both organic and inorganic components of the smear layer. Alternate use of NaOCl and EDTA solutions during irrigation provides the most cost-effective method of disinfecting the root canal system.
Other all-in-one irrigation solutions such as BioPure MTAD (Tetracycline, citric acid and a detergent) or QMix (EDTA, CHX and a detergent) have also been shown to be very effective in removing the smear layer and killing the micro-organisms while respecting the dentinal structure.
Removing posts from canals could be pain in the neck sometimes. There are many ways to remove a post from a canal such as cutting all the sound tooth structure around the post with a large round bur (I hope nobody is using this method) or using ultrasonic device and frying a few expensive tips and ultimately the root and surrounding structure (can you smell the lawsuit?).
One method that has allowed me to remove stubborn posts more conservatively and relatively quickly is using the Ruddle Post Removal System (PRS) Kit.
The kit comes with a series of post removal trephine burs (#1 to #5) and corresponding post removal tubular taps. The process of port removal starts by removing the majority of the build-up material from around the post. Then a trephine bur can be used to mill the post to a specific size (usually the biggest size that starts to mill the post). The corresponding tubular tap is then used in counter-clockwise direction to engage the post. The tap is screwed in to the point that it locks and starts to disengage the post from the canal. If the post cannot be removed easily, the extracting plier and cushions will do the job beautifully. The short video clip below demonstrates how easily a post can be removed from a canal:
One common question that many of my friends ask me is “How do you deal with a hot tooth?”
After giving adequate block injections and local infiltrations, I usually use intraligamental or intraosseous type of injections. My first choice for a few years has been using a syringe called Paroject. This syringe is used for intraligamental injections which is in a way intraosseous as well since the pressurized anesthetic solution in the PDL space will penetrate into the adjacent cancellous bone. I give 6-point intraligamental injection around the hot tooth using local anesthetic without epi and this usually does wonders.
Another effective method is using the intraosseous anesthesia with the Stabident and X-Tip systems. The details of the two systems can be reviewed in the article “Intraosseous Anesthesia” from the Endodontics: Colleagues for Excellence (Winter 2009) publication by the American Association of Endodontists (AAE).
Have I been 100% successful with all the hot teeth I have dealt with in the past few years? Absolutely not! If that happens, don’t forget there is always the good old practice-builder technique: the “Intrapulpal Injection“.