Why I think Calcium Hydroxide Should be used
in Root canal Treatment

             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!

I am a general dentist  that tries to be holistically oriented in my treatment, and I try to find reasonable approaches rather than black-or white dogmatic ones.  I try to consider and balance what we can learn from scientific research with what has been suggested by the alternative  healing community.  Many times, even if absolute scientific proof does not yet exist, the ideas coming from the alternative community seem to make sense and urge us to at least attempt to honor them by modifying our techniques as long as they don't totally conflict  with what has been shown scientifically to be valid.


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.

rootcanalsystem.jpg (17932 bytes)   

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.

For peer-reviewed research abstracts, see

                    Journal of endodontics, volume 22, Number 8, August 1996
                    Changes in ph at dentin surface in roots obturated with calcium hydroxide paste


Effect of 2% chlorhexidine gel mixed with calcium hydroxide as an intracanal medication on sealing ability of permanent root canal filling: a 6-month follow-up

Department of Endodontics, University of Athens, Athens, Greece. ekontak@dent.uoa.gr


J Endod. 2003 May;29(5):338-9.

Efficacy of calcium hydroxide: chlorhexidine paste as an intracanal medication in bovine dentin

Oregon Health & Science University, Portland 97201, USA.


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.

Here's an example of a badly infected root canal with lots of bone loss -"cavitation" - and the result of my treatment using calcium hydroxide.  Would the result have been the same  using conventional treatment?  Perhaps.  We can't know for sure.  But this is the kind of result I have seen over the years.... if not every time, certainly by far most of the time.  Keep in mind that NO treatment can boast 100% success - mine or anybody else's,  conventional or "holistic", with laser, ozone, supplements, antibiotics, or not.

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:

More research articles regarding calcium hydroxide + chlorhexidine used together, for those of you that like to read such things:  

2010 Jul-Aug;59(7-8):415-21.

Antimicrobial analysis of chlorhexidine gel and intracanal medicaments against microorganisms in root canals.
Valera MC, Salvia AC, Maekawa LE, Camargo SE, Carvalho CA, Camargo CH, Koga-Ito CY.

Source: Department of Restorative Dentistry, São Paulo State University-UNESP, São José dos
Campos, São Paulo, Brazil.

AIM: The aim of this paper was to evaluate the antimicrobial activity of 2% chlorhexidine gel (CLX) associated with various intracanal medicaments against Candida albicans and Enterococcus faecalis inoculated in root canals.

METHODS: It was verified that the instrumentation with CLX reduced the number of CFU/ml significantly when compared with the confirmation collection (control). However, the use of the ICM was only capable to eliminate completely the microorganisms in the root canals without difference statistics between them.

CONCLUSION: Although the use of 2% chlorherixidine gel reduces the number of microorganisms significantly, only the ICM [intracanal medication] calcium hydroxide and calcium hydroxide associated with chlorhexidine are able to eliminate these microorganisms completely.


CHX and Ca(OH)2 [Chlorhexidine and Calcium Hydroxide] 

Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006 Oct;102(4):544-50. Epub 2006 Aug 4. 
In vitro evaluation of the antimicrobial activity of calcium hydroxide combined with chlorhexidine gel 
used as intracanal medicament.
Gomes BP, Vianna ME, Sena NT, Zaia AA, Ferraz CC, de Souza Filho FJ.
The aim of this study was to investigate the antimicrobial activity of calcium hydroxide (Ca(OH)2) combined with 2% 
chlorhexidine gluconate (CHX) gel against endodontic pathogens and to compare the results with the ones achieved by 
Ca(OH)2 mixed with sterile water and by CHX gel alone. Two methods were used: the agar diffusion test and the direct 
contact test. Ca(OH)2 + 2% CHX gel produced inhibitory zones ranging from 2.84 to 6.5 mm, and required from 30 seconds 
to 6 hours to eliminate all tested microorganisms. However, 2% CHX gel showed the largest microbial growth zones from 
4.33 to 21.67 mm, and required 1 minute or less to inhibit all tested microorganisms. A paste of Ca(OH)2 plus sterile 
water inhibited only the microorganisms with which it was in direct contact and required from 30 seconds to 24 hours 
to kill all tested microorganisms. 
In conclusion, 2% CHX gel + Ca(OH)2 showed better antimicrobial activity 
than Ca(OH)2 manipulated with sterile water.
Antibacterial efficacy of calcium hydroxide and chlorhexidine gluconate
irrigants at 37 degrees C and 46 degrees C.
Evanov C, Liewehr F, Buxton TB, Joyce AP.
This study investigated the ability of two endodontic irrigants to eliminate Enterococcus faecalis from 
dentinal tubules, and whether their antimicrobial action was enhanced by heat. The lumens of disks 
prepared from extracted bovine roots were infected with E. faecalis and incubated for 72 h. Specimens 
were then filled with saline, 10% calcium hydroxide (Ca(OH)2), or 0.12% chlorhexidine gluconate (CHX) at 
24 degrees C or 46 degrees C and incubated at 37 degrees C or 46 degrees C. The samples were then 
pulverized and plated to quantify residual bacteria. No statistical difference (p > 0.05) in bacterial 
growth was seen between the two saline groups, or between the two medication groups at a given temperature. 
CHX and Ca(OH)2 at either temperature produced significantly less growth than either saline group, and 
CHX or Ca(OH)2 at 46 degrees C produced significantly less growth than either group at 37 degrees C. 
Heat enhanced the antibacterial action of both experimental irrigants against E. faecalis, but heating 
saline produced no increase in bactericidal effect.
Eur J Oral Sci. 2004 Aug;112(4):326-31. 
In vitro antibacterial effect of calcium hydroxide combined with chlorhexidine or iodine potassium 
iodide on Enterococcus faecalis.
Siren EK, Haapasalo MP, Waltimo TM, Orstavik D.
Several studies have shown a higher success rate of root canal therapy when the canal is free from bacteria 
at the time of obturation. Treatment strategies that are designed to eliminate this microflora should 
include agents that can effectively disinfect the root canal. Enterococcus faecalis is often associated with 
persistent endodontic infections. While in vivo studies have indicated calcium hydroxide to be the most 
effective all-purpose intracanal medicament, iodine potassium iodide (IKI) and chlorhexidine (CHX) may be 
able to kill calcium hydroxide-resistant bacteria. Supplementing the antibacterial activity of calcium hydroxide 
with IPI or CHX preparations was studied in bovine dentine blocks. While calcium hydroxide was unable to kill 
E. faecalis in the dentine, calcium hydroxide combined with IKI or CHX effectively disinfected the dentine. 
The addition of CHX or IKI did not affect the alkalinity of the calcium hydroxide suspensions. It may be 
assumed that combinations also have the potential to be used as long-term medication. Cytotoxicity tests 
using the neutral red method indicated that the combinations were no more toxic than their pure components.
J Endod. 2003 May;29(5):338-9. 
Efficacy of calcium hydroxide: chlorhexidine paste as an intracanal medication in bovine dentin.
Evans MD, Baumgartner JC, Khemaleelakul SU, Xia T.
The purpose of this study was to evaluate the antibacterial efficacy of an intracanal medication composed 
of calcium hydroxide with 2% chlorhexidine. Dentin from 24 bovine incisors was used. The incisors were made 
into standardized cylindrical segments of dentin and infected with Enterococcus faecalis. They were then 
treated with an intracanal paste composed of calcium hydroxide and sterile water or an intracanal paste 
composed of calcium hydroxide and 2% chlorhexidine for 1 week. Dentin shavings were collected, suspended 
in solution, and spread on brain-heart infusion agar. After incubation, colony-forming units were enumerated. 
The amount of bacteria per mg of dentin was determined. The calcium hydroxide paste with 2% chlorhexidine was 
significantly more effective at killing E. faecalis in the dentinal tubules than calcium hydroxide with water.
Int Endod J. 2003 Apr;36(4):267-75. 
Effectiveness of 2% chlorhexidine gel and calcium hydroxide against Enterococcus faecalis 
in bovine root dentine in vitro.
Gomes BP, Souza SF, Ferraz CC, Teixeira FB, Zaia AA, Valdrighi L, Souza-Filho FJ.
AIM: To evaluate the effectiveness of 2% chlorhexidine gluconate gel and calcium hydroxide (Ca(OH)2) 
as intracanal medicaments against Enterococcus faecalis.
METHODOLOGY: One hundred and eighty dentine tubes prepared from intact freshly extracted bovine maxillary 
central incisors were infected in vitro for 7 days with E. faecalis. The specimens were divided into four 
groups, according to the intracanal medicament used, as follows: Group 1: 2% chlorhexidine gluconate gel; 
Group 2: calcium hydroxide in a viscous vehicle (polyethyleneglycol 400); Group 3: 2% chlorhexidine 
gluconate gel + calcium hydroxide and Group 4: Brain Heart Infusion (BHI) broth (control group). 
The medicaments were placed into the canal lumen and left there for experimental times of 1, 2, 7, 15 
and 30 days. After each period, irrigation with sterile saline to remove the medicament was performed 
and the canals were dried with sterile paper points. Dentine chips were removed from the canals with 
sequential sterile round burs at low speed. The samples obtained with each bur were immediately collected 
in separate test tubes containing BHI broth. The tubes were incubated at 37 degrees C and daily observed 
for microbial growth, visualized by the medium turbidity. 
RESULTS:  Chlorhexidine gel alone completely inhibited the growth of E. faecalis after 1, 2, 7 and 15 days. 
Calcium hydroxide allowed microbial growth at all experimental times. The combination of chlorhexidine and 
Ca(OH)2 was effective after 1 and 2 days demonstrating 100% antibacterial action; however, its antibacterial 
activity reduced between 7 and 15 days. 



Update 2014:  I have been using a mixture of calcium hydroxide mixed with 2% chlorheidine up to the present time with  very good results. Up until a few years ago I used it but with much lower concentration chlorhexidine and before that, only mixed with distilled water.

I hope this information has been helpful to understand root canal treatment options.  There is a lot of confusing and contradictory information floating around on the internet.  Read it all if you can and see what makes the most sense to you.  Good luck!



Michael C. Goldman, DDS


General and Cosmetic Dentistry

3815 East-West Highway

Chevy Chase, Maryland 20815 Phone (301) 656-6171



Michael Goldman DDS
3815 East-West Highway
Chevy Chase, Maryland 20815


More info about the following is available  if you select  "topics".

Holism in dentistry is an approach to dental treatment, primarily  caring for  patients' health and safety from both a conventional as well as  "alternative healthcare" point of view.   It is sometimes called "biological" dentistry or "biocompatible" dentistry.  In it's fullest sense, I believe it   acknowledges and deals with  the mind, body and spirit of the patient, not just his or her "teeth".  See Topics / Info.....

Cosmetic dentistry is about doing   quality , esthetic dentistry in a way that looks natural to begin with, and furthermore,   can even  improve  one's  attractiveness through techniques such as bonding, bleaching, veneers, caps, implants and more.  It can   be like "instant orthodontics" in correcting  crooked, twisted or misplaced teeth in many instances.  Dark or misshapen teeth can be restored.   Smiles that lack youthful vigor or beauty can be revitalized! See Topics / Info..

Bleaching, veneers, bonding, caps, bridges, and implants  are cosmetic dentistry treatments that are also  discussed in  Cosmetic Dentistry, and more...located in the Bethesda, Chevy Chase, Maryland 20815 area near Washington DC.