Why I think Calcium Hydroxide
Should be used
Michael C. Goldman, DDS
*Note: Be sure to read my other articles on this site [ See "Topics/Info" ] on Root Canal Treatment to get the full story about my views regarding root canal treatment.
Since you are reading this there's a good chance you are thinking [or are sure] that you need a root canal. Also, you have probably been reading lots of conflicting ideas about whether root canals are "good" or "bad". If you are holistically or "alternative medicine" oriented, you have probably read information suggesting that all root canals will make you sick and cause all sorts of problems in your body - both near and far away from that tooth. You may be familiar with the writings of Dr. Weston Price or Dr. George Meinig, both of which will scare the heck out of you when it comes to root canal treatment!
If you are not already familiar with the basics about just what root canal treatment "is", the following is a brief description:
The anatomy of a tooth is like this: There is a hollow space running down the center of each root. That is the nerve canal. It can have curves and small offshoots or branches to make it more complex than a straight "tube", but in all, that total space is the nerve- or root-canal space. In a healthy tooth the nerve and small blood vessels occupy that space. When root-canal treatment is done, that canal is cleaned out to render it empty. Medications are usually used to "sterilize" that space...to kill any bacteria that might be remaining after physically cleaning it out. Then it is filled up with various techniques and materials to obliterate the space.
What we know is that it is actually more complex than that. Not only is there this large central nerve-canal space to worry about, but, rather, that there are millions of little tunnels coming off the central nerve-canal space radiating through the body of the tooth root to the exterior surface of the tooth root. The tooth root surface is in contact with the blood stream and then bone. The "little tunnels" or dentinal tubules, as they are correctly called comprise literally miles of tunnels into which bacteria from the nerve-canal space can go and hide, well away from the physical and chemical efforts of the dentist. This has been shown and confirmed by the electron-microscope!
What does all this mean? What are the implications? Well it seems to me there are several. First, it seems ever more important to do the root-canal treatment as early as possible. In addition to making the treatment easier for you, it minimizes the opportunity for infection to develop inside the tooth which might be able to subsequently hide in the tubules and from there spread havoc around your body.
There are basically three steps to doing root canal treatment. First, the nerve tissue inside the hollow nerve canal(s) is removed with tiny steel instruments, starting with very narrow ones and gradually using larger and larger ones to clean it out as completely as possible. The larger sized ones are still only about 1/32 of an inch thick. That removes the bulk of the remaining tissue inside the tooth root.
Since there is still some tissue remaining that can't be removed with metal instruments, and since there will likely be bacteria, bits of tissue, and products of infection [pus etc.] in there, chemicals are used in the Second Step to remove them in an attempt to "sterilize" the canal space. Recently lasers have been sometimes used for this. I have written another article just on the topic of laser-assisted root canal treatment on this site, so I won't go into detail here except to say that while it "sounds" like it may be a good idea, the jury is not yet in on it and there are possible reasons why it might NOT be a good idea. Time will tell....
Third, when to tooth has become comfortable and efforts have been used to get the canals as sterile as possible, then the hollow space in the nerve canal is totally filled up so fluid and bacteria cannot collect again in there. Several different materials and techniques are available to do this. It is technically a tricky and difficult job, so often the dentist will use the materials and technique that he/she is most comfortable and skilled with. It would be very difficult to prove that one material or one technique is better than the others, but only that a particular dentist might do a better job with a technique he/she is "good at". While we "can" learn new techniques, it takes time and practice to get good at any one of them... so we each tend to use what works for us.
So What about the Calcium Hydroxide?
Having established the basic groundwork above I will now focus on the second step of the root canal treatment: Chemical Cleaning and Disinfection. The information was reiterated in an article published in dentalCEtoday.com in the February 2010 edition.
The author states that "it has been shown that the number of bacteria can be significantly reduced, but not [eliminated]" by mechanical instrumentation used in the first step of treatment.
Therefore, he says, the mechanical instrumentation must be augmented with antimicrobial irrigant. Sodium hypochlorite - similar to Clorox Bleach - is almost universally the irrigant of choice in root canal treatment, and has been for many, many years. Various strengths of it are used but the research shows a wide range of helpful dilutions with not much difference in effect. It is very helpful for a couple of reasons. First it is highly antimicrobial for the vast majority of bacteria, viruses, spores, fungi and protozoa found in root canals. Secondly it chemically helps to actually "dissolve" remaining bits of tissue that could not be removed with the metal instruments. It is the only irrigant that can disrupt and remove microbial biofilm from the infected root canal system. Research, however, has shown that Sodium hypochlorite, while almost universally depended on, will not completely kill all the bacteria in the tooth in up to at least 50% of cases studied. Research over many, many years has shown that the addition of Calcium hydroxide as a medication inside the canal significantly further reduced bacteria.
Many different medications inside the root canal have been used over the years and all require much more than a few minutes of use in the canal to be effective. Root canal treatment done in only a single office visit limits medication use to minutes - rather than hours or days or weeks as in the case of multiple visit treatment. According to Bystrom, a well respected researcher in endodontics [root canal treatment], leaving Calcium Hydroxide inside the canal for 4 weeks [which is what I do routinely] renders the canals bacteria free in 97% of cases studied.
Other medications commonly used like CMCP or phenol only succeeded in about 66% of cases. Other research using Calcium Hydroxide, but for SHORTER periods of time, like one or two weeks, showed no significant improved effectiveness over the CMCP or Phenol. It seems very important to me to leave the Calcium Hydroxide in the canals for at least 4 weeks for maximum effectiveness.
Why does Calcium Hydroxide work? It is a very alkaline [ high pH of up to pH of 14 or so ]. Being so alkaline it does several good things. It dissolves little bits of remaining tissue that the metal files missed. It dissolves the cell membranes of bacteria, which can cause toxicity even when the bacteria are dead, but by dissolving this cell wall, it eliminates the toxicity effect. Also the Calcium Hydroxide gradually dissolves into the moisture in the miles of tiny tubules that make up the dentin from the nerve canal out almost to the outside surface of the tooth root. We know that bacteria can and do get stuck in these tiny tube-like tubules and can effectively "hide" away from our cleaning efforts in the main nerve canal space. As the Calcium Hydroxide dissolves deeper and deeper into the tubules it can kill bacteria hiding there.
Research has demonstrated that a change in pH up to 14 can be measured out at the outside surface of tooth roots treated with Calcium Hydroxide, indicating that it has penetrated from the nerve canal out to the surface. Does it penetrate every single tubule that way? We can't say that we know it does but it would seem reasonable to assume it probably does come close to that. If we drop some salt into a bucket of water, it dissolves out the same way and does not miss some of the water.
Journal of endodontics, volume 22, Number 8, August 1996
Changes in ph at dentin surface in roots obturated with calcium hydroxide paste
Some of the Calcium Hydroxide dissolves out into the bone around the end of the root where the bone normally gets damaged by the root canal infection and the changes in chemistry that result from it. The Calcium Hydroxide helps to change this altered chemistry back to normal and calms the bone [ which is where a lot of the pain comes from ] and helps to initiate bone repair processes to speed healing.
All of these helpful effects of Calcium Hydroxide are gentle and slow. That's why leaving it in the tooth for one or two weeks is not so very effective. But given enough time it gently helps in all those ways described above. It should not be left for more than 6 weeks, however, because it gradually begins to dissolve out and that would just create space for fluid and bacteria to collect again. So, I try for 4 weeks. In special cases I will go 6 weeks, remove it and place a fresh dose of it for another 4 to 6 weeks.
Are there any problems with Calcium Hydroxide?While Calcium Hydroxide does many wonderful things, it has been found to lack in one area. There are two microbes important in root canal treatment that it does not kill: Candida and E- faecalis. When root canal treatment fails as it sometimes does, very often E faecalis is found in the re-infected canals and it is often thought to be responsible for the failure. Fortunately, chlorhexidine has been found to be very effective against it.
Mixtures of chlorhexidine and Calcium Hydroxide have been shown to have additive benefit against Candida and E- faecalis. That is, the mixture is more effective than either one alone. I have been using such a mixture now [Feb. 2010] for a few years and have found it to be very effective in reducing discomfort and promoting good healing. with absolutely zero negative side effects that I have seen. In the article mentioned above, the author states that the mixture, when used for 4weeks [ which is exactly what I have been doing ] reduces the inflammation in the periodontium [ the supporting bone and soft tissue around the tooth root ] and results in less root resorbtion [damage to the root].
Chlorhexidine, which you may have seen or used in the form of "Peridex", a prescription mouth rinse for periodontal problems, can be used along with Sodium hypochlorite as a canal irrigant. It is safe and innocuous except to the germs that reside in the mouth and root canals!
Calcium hydroxide, in my opinion, while a very "old" root canal medication, is still recognized to be more effective than other more "modern" medications, but is only infrequently used and usually only for special situations. From my point of view, there is no reason why it should not be routinely used and for a long enough time period to do the job (about a month). The norm today among most general dentists as well as most root canal specialists is to either finish the treatment in one appointment or perhaps in two appointments about a week apart. It takes extra time and effort to treat root canals with calcium hydroxide, so it is often seen as "inefficient" or a waste of time, since the single visit techniques seem to work well enough for most patients.
Most root canal specialists - endodontists - were trained in the calcium hydroxide technique, so most of them do know how to do it properly, but at the same time most of them don't seem to think the extra time and effort is worth it, except in special problem cases.
added July 2012:
research articles regarding calcium hydroxide + chlorhexidine used
together, for those of you that like to read such things:
Minerva Stomatol. 2010 Jul-Aug;59(7-8):415-21.
Antimicrobial analysis of
chlorhexidine gel and
intracanal medicaments against
microorganisms in root canals.