The root canal is the hollow area within each tooth that normally encloses the pulp, the living part of the tooth that contains blood vessels, nerves, and connective tissue. If the pulp becomes badly diseased or injured, root canal therapy may be able to save the tooth by removing the pulp and filling the canal with a substitute material. Most cases require one or two visits, after which the patient’s dentist will place a crown or other restoration on the tooth to protect the tooth and restore full function . Ideally, the filling material should be inert and easy to handle. Standard root canal therapy uses gutta percha, the coagulated sap of certain tropical trees.
In the early 1950s, a Swiss dentist named Angelo Sargenti began filling roots with a paste that contained paraformaldehyde. Over the years, the formula’s name and ingredients have changed many times, but paraformaldehyde has always been included. The names used have included “Sargenti Paste,” “N2,” “N2 Normal,” “N2 Medical,” “N2 Universal,” N2 Apical,” “RC-2B,” “RC-2W,” “TCM,” “White One-Step Endodontic Formula,” and “Endodilato.”
Sargenti died in 1999, but his unconventional methodology lives on. His followers claim that the paste—commonly referred to as “N2″—is easier and faster to place than gutta-percha. However, when paraformaldehyde contacts water, it forms formaldehyde (a preservative used in embalming fluid). Sargenti’s procedure may save a tooth, but it is much less predictable than standard treatment. The pressure needed to reach the tip of the root can force the paste into surrounding tissues where it can cause serious and painful injuries if the paste contacts jaw nerves or the maxillary sinuses above the upper jaw.
Many studies have been done to determine whether the materials used in root canal procedures can affect the tissues surrounding the tips of treated teeth. One study, for example, compared the effect of a Sargenti formula and gutta percha in rhesus monkeys. When the filling material was confined to the root, the reactions of the tissue surrounding the teeth were similar and temporary. However, in about half of the specimens when the filling material extended beyond the root tip, the Sargenti formula caused serious damage that did not occur with gutta percha. Noting that overfilling can occur occasionally even in the hands of the most proficient, the author warned that the Sargenti formula-filled teeth showed evidence of “greater violence.” 
In another study, the researchers filled roots of extracted teeth with N2, gutta-percha, or another root canal material and placed them into laboratory containers of distilled water. After a year, they found that when placed into cultures of connective tissue and periodontal ligament cells, water samples from the N2 preparations would kill cells but samples from the gutta-percha and all but one of the other preparations would not. The study indicates that Sargenti material is not inert and can damage tissues near the root tips even when the roots are not overfilled .
Root canal therapy is called endodontics. The recognized specialty group is the American Association of Endodontists (AAE), which has more than 6,500 professional members. Active membership is available to practicing endodontists who successfully complete a two-year postdoctoral program in endodontics approved by the American Dental Association’s Commission on Dental Accreditation. The AAE considers paraformaldehyde-containing filling materials or sealers to be unsafe and ineffective and considers their use to be substandard care. Its 1991 position statement is still posted on its Web site and considered current. It says:
Paraformaldehyde-containing endodontic filling materials or sealers (frequently known as Sargenti pastes, N-2, N-2 Universal, RC-2B or RC-2B White) should not be used for endodontic treatment because those materials are unsafe. Extensive scientific research has proven unequivocally that paraformaldehyde-containing filling materials and sealers can cause irreversible damage to tissues near the root canal system including the following: destruction of connective tissue and bone; intractable pain; paresthesia and dysthesia of the mandibular and maxillary nerves; and chronic infections of the maxillary sinus. Moreover, scientific evidence has demonstrated that the damage from paraformaldehyde-containing filling materials and sealers is not necessarily confined to tissues near the root canal. The active ingredients of these filling materials and sealers have been found to travel throughout the body and have been shown to infiltrate the blood, lymph nodes, adrenal glands, kidney, spleen, liver and brain. . . .
Public health concerns and litigation have made the AAE aware of a significant number of patients who have suffered injuries as a result of treatment with paraformaldehyde-containing filling materials and sealers. Undoubtedly, there are many other patients who have also suffered injuries because of these materials, but whose injuries have not been publicly disclosed .
In 1991 the ADA Council on Dental Therapeutics abandoned its long-held neutral position on the Sargenti method and resolved:
In view of the fact that sufficient data have not been submitted to the Council on Dental Therapeutics to establish the safety of paraformaldehyde-containing root canal filling materials and that the FDA has not approved any products with this formulation, the council cannot recommend use of these products at this time .
For the same reasons, the Sargenti method is not taught in any American dental school.
In 1969, Sargenti followers formed the American Endodontic Society (AES), which now offers training, a Web site, a newsletter, and political support. Its mission is “to provide educational and scientific information on simplified endodontic procedures; to protect and preserve the right of the general dentist to perform those procedures for which he is qualified by education and experience.” The 2006 dues rate for “active/dentist” members was $195. Since at least 1988, the Encyclopedia of Associations has reported that AES’s membership as “10,000.” However, the income from “membership dues and assessments” reported in its 2006 Form 990 tax return was only $76,070, so the total number of active members appeared to be less than 400. In a telephone conversation in 2007, I asked AES Secretary-Treasurer Alvin H. Arzt, D.D.S. how many active members AES has. He said about 2,900 to 3,000 . When I pointed out the discrepancy, he replied that there were honorary members and others who were actively supportive, and that that’s the number that the accountants put down. AES’s 2008 annual meeting was attended by only a dozen or so dentists, most of whom were AES officers or board members.
Arzt, who is president of the N2 Products Corporation, also told me that the company’s N2 had passed Phase II testing based on a submission that compiled 5,000 cases . A 2007 AES newsletter reported that the application process had stalled because AES had not been able to find a company to manufacture N2 and gather data on its use . However, Arzt said that AES has found a suitable manufacturer and hoped to go forward with a 1-year study that would persuade the FDA to approve the company’s paste . When I asked whether a report on the 5,000 cases had been published, Arzt said that no dental journal would consider publishing it. When I expressed surprise that AES itself had not made the data publicly available, he replied that a summary had been given to members, but the important thing was that the data were accepted by the FDA. He also alleged that endodontists oppose use of the N2 paste solely because it enables general dentists to do root canal treatment at lower cost. Although the dentists who use N2 tend to charge less than endodontists, I believe that opposition—which is not limited to endodontists but includes other dentists and dental educators who do not perform endodontic treatment—is based on safety concerns rather than economic reasons.
If paraformaldehyde paste extrudes beyond the root tip, it will emit formaldehyde, which can erode the surrounding bone, destroy nearby connective tissues, and lead to numbness, paresthesias (feelings of “pins and needles”), jaw pain, and infection of the maxillary sinus . The percentage of patients who are injured is not high, and some problems can be resolved with surgery and/or injections of the affected tissues with an anti-inflammatory drug. In some cases, however, the numbness and paresthesias are permanent and pain is lifelong and can’t be adequately controlled with narcotic drugs.
Stephen Cohen, D.D.S., a clinical professor of endodontics at the University of Pacific School of Dentistry and the University of California School of Dentistry, has served as an expert in more than 40 cases in which injured patients took legal action . The most noteworthy is that of Laurie Ann Shoop, a Florida woman. In 1984, she went to her family dentist who, unknown to her, was using N2 paste. During the following six years, the left side of her jaw had to be removed, her jaw was wired shut for 41/2 years, and she had three jaw transplants . Her lawsuit suit against the dentist was settled in 1990 for $1 million, which was the limit of his malpractice insurance policy. By that time she had had more than 40 operations, and she has had more since that time.
Another important case is that of Lorraine M. Hellier (now called Lorrie Kruse), an Alabama woman who suffered permanent nerve damage as a result of overfilling by a dentist who used the Sargenti paste. Three days later, she began experiencing severe pain that has persisted despite delayed surgery that removed the involved tooth and Sargenti paste from the underlying main sensory jaw nerve. The pain, which appears to be permanent, is severe without medication and barely tolerable with strong medication that has unpleasant side effects. The x-rays below demonstrate what happened. The picture to the left shows the extruded N2 paste (the white area) below the tips of the roots. The picture to the right, which was taken before the N2 was administered, shows no such area.
Hellier complained to the Alabama dental licensing board that she had not been told in advance about the risks of paraformaldehyde paste and that afterward, the dentist and two associates failed to tell her that it was responsible for her symptoms. In 2007, the three dentists signed consent agreements under which they were guilty of gross negligence and assessed administrative penalties totaling $13,500. They also agreed to (a) serve one year’s probation, (b) take continuing education courses related to the use of gutta percha, and (c) use a suitable consent form that explains the risks of the Sargenti technique if they continue to use it . Hellier sued the California pharmacy that had supplied the paraformaldehyde-containing powder to the three dentists and settled out-of court for $40,000. She also sued the dentists for negligence, failure to provide informed consent, and concealing the nature of her injury. Her suit charged that the concealment delayed her opportunity to have microsurgery before her jaw nerve was mummified by the Sargenti paste . The case was settled in 2008 with payment of an undisclosed amount. Her attorney, Edwin J. Zinman, DDS, JD, is a former periodontist who specializes in medical and dental malpractice cases.
Another lawsuit is that of Claudia Megaro, who in 2000 consulted Dominivc J. Cicero, D.M.D. in Philipsburg, New Jersey, who practiced what he called “holistic dentistry.” The directory of the American Holistic Dental Association describes his services as ” Orthopedics (TMJ), Cranial Sacral Therapy, Nutrition, De-Tox Heavy Metals, Cranial Osteopathy, Amalgam Free,Nutritional Counseling, Applied Kinesiology, Comprehensive Mercury Removal.” Documents in the case indicate that Megaro sought root canal treatment for a single tooth but was advised to have all of her amalgams fillings removed and replaced. She was also advised to have two other root canal treatments, one in a tooth that was giving her no trouble. During the next two years, she saw the Cicero regularly for various procedures but developed persistent, severe pain. Her lawsuit charged that he failed to refer her for appropriate medical care for what ultimately turned out to be a severe infection (osteomyelitis) of her jaw bone . After the suit was filed, Megaro discovered that the filling material used for her root canal treatments was RC-2W. During a deposition, the Cicero testified that he had used this material for several years but did not know its ingredients or where he had obtained it . During telephone conversations, Megaro told me that she was not told that her root canals would be filled with a nonstandard material. She also said that she has has had multiple operations with medical bills totaling over $500,000 . The suit was settled in 2008 with payment of an undisclosed amount. After investigating a complaint from Megaro and the records from her lawsuit, the New Jersey Denntal Board concluded that Cicero’s treatment of her constituted “gross and repeated acts of negligence.” In 2010, Cicero and the board entered into a consent order under which he agreed to a license surrender (deemed a revocation) and payment of $670.50 for costs of the investigation .
The Sargenti Opposition Society was formed in 2008 to campaign against the use of paraformaldehyde-containing paste and to help patients identify and avoid the dentists who use it.
The Cincinnati Insurance Company, which covered the dentists Hellier sued, has routinely asked dentists whether they use Sargenti paste or cement . In 2010, AES president Mark Piacine, D.D.S., reported that Cincinnati and the Medical Protective Company would no longer cover those who use the Sargenti technique in their practice .
The FDA has banned interstate marketing of Sargenti-type pastes, but pharmacists can legally prepare them for local use. In a 1991 letter to the AAE, an FDA official stated:
We have repeatedly advised proponents of this drug that the N2 material is considered to be an unapproved new drug. Further, it may not legally be imported or distributed in interstate commerce until an applicant has submitted a new drug application (NDA) with convincing evidence of safety and effectiveness for the recommended use, and FDA has approved the application. . . .
We have allowed quantities of N2 (Sargenti) Paste which do not contain heavy metals to be distributed for single patients in conformance with the practice of pharmacy. The maximum amount of the non-heavy metal formulation which we permit to be dispensed under the practice of pharmacy is 5 gm. Bulk shipments by pharmacists to dentists are not permitted .
In 1975, at a Congressional hearing, three prominent dental educators stated that Sargenti pastes were inherently dangeroius and described how they had tried to persuade FDA officials to drive them from the marketplace. No FDA representative attended the hearing but the Director of the FDA Bureau on Drugs submitted a statement that said the agency did not take this approach because it was not sure that the courts would uphold its position that they were unapproved new drugs .
N2 proponents have sought FDA approval on and off for more than 45 years. The first NDA was submitted in 1962 by the AGSA company and withdrawn in 1967. In 1971, after completing a lecture tour in the United States, Sargenti met with eight FDA officials to discuss N2 regulation. The memorandum describing what happened portrays Sargenti as evasive, long-winded, irrational, and emotionally unstable .
In 1975, an FDA dental advisory panel concluded that data submitted for another NDA were not sufficient to warrant FDA approval. The committee stated:
Uncontrolled clinical observations suggest that proper preparation and proper filling of root canals with any of the materials currently in use, including “N2” and “RC-2B,” will result in a high percentage of retained asymptomatic teeth. However . . . insufficient scientifically valid data are available to permit a judgment that “N2” and “RC-2B” can be “generally recognized as safe and effective.” Moreover, the Committee is concerned that the therapeutic value of some of the ingredients in the materials has not been established .
In 1983, the N2 Products Corporation opened the current NDA for “N2 Universal.” During the ensuing nine years, in response to FDA requests, the company provided additional information that culminated in 1992 with the submission of 9,514 case histories and other data. However, in 1993, following another hearing , the FDA Dental Products Advisory Committee concluded that the submitted information did not meet the agency’s standards for adequate and well-controlled studies and recommended that new studies be required . During the hearing, an FDA statistician noted that the case reports had no statistical significance because they had not been compared to a control group who had received gutta-percha and that:
A variety of filler/sealers were used. Most of them were of the N2 basic format but they had the other additives included. Due to the fact that these subjects were submitted as successful cases, they really do not add anything to our comparison, as far as I am concerned, from a statistical perspective. It is a lot of cases but what is the denominator? How many people actually received filler during this period, and how many failures were there in that? I do not have an adequate denominator and I do not have an adequate numerator .
In 1991, the FDA ordered a Chicago drugstore to stop selling Sargenti Root Canal Powder in interstate commerce . In 1994, the FDA initiated a seizure of a formaldehyde-containing paste after its owner, Harvey Altholtz, D.M.D, who operated Altholtz’s Dental Clearing House, in Simsbury, Connecticut, had ignored warnings to stop marketing it. Two years later, a federal judge ordered the seized product destroyed and ordered the company to pay the costs related to the enforcement action. The FDA had learned about the company after health professionals accused it of falsely advertising that its White One-Step Endodontic Formula “meets FDA standards” and was “FDA sanctioned.” 
State and Provincial Regulation
In 1996, the Florida Board of Dentistry determined that “the use of ‘Sargenti Cement’ (e.g., N2, RC2B, or RC2W or essentially similar compounds) as an endodontic filling material or cement does not meet the minimum standards of performance for competent dental practice in Florida.”  Over the years, a few state dental licensing boards have issued warnings and/or banned the use of paraformaldehyde-containing endodontic products. As far as I know, no states currently have an outright ban, but some consider their use to be substandard care and might take disciplinary action in response to individual complaints.
In 2004, the Royal College of Dental Surgeons of Ontario reminded its members that Health Canada had not authorized N2 for sale in Canada and that the use of paraformaldehyde-containing root-canal materials would be considered substandard practice. The warning came in response to a flyer from a Toronto-area dental supply company that had advertised the sale of N2 Universal root canal cement. After the College complained, Health Canada investigated and the company stopped selling the material . (Health Canada’s regulatory authority is similar to that of the FDA.)
In 2005, Wisconsin reprimanded Peter Hehli, D.D.S. of Applelton, Wisconsin and prohibited him from continuing to use the Sargenti technique . It also permitted Kenneth R. Sachtjen, DDS of Madison, Wisconsin to permanently surrender his license to settle charges that he had given a patient improper treatment that included two root canals using a version of Sargenti technique .
In 2008, in response to an inquiry from the New Jersey Dental Association, the New Jersey State Board of Dentistry clarified that the use of Sargenti Paste and other paraformaldehyde-containing endodontic filling materials and sealers falls below the accepted standards for the profession .
In 2009, an American Endodontic Society newsletter contained a statement from AES director Raymond Della Porta, Sr., D.M.D. of Vero Beach, Florida, that he was in his 35th year of using the Sargenti system with over 5,000 cases treated . Noting Florida’s1996 rule, a Sargenti Opposition Society member asked the Florida Board of Health to investigate. In 2011, after locating two former patients, the Department charged Della Porta with substandard care based on his use of Sargenti cement in root canal treatments of these patients . In 2012, Della Porta and the board signed a settlement agreement under which the board would issue a letter of concern and order him to (a) pay a $5,000 fine, (b) refund out-of-pocket fees and costs to the patients, and (c) permanently refrain from using Sargenti material in any endodontic procedures . Shortly afterward, however, Della Porta filed a motion for reconsideration which noted that he had practiced for many years without disciplinary action, had stopped using the Sargenti material, and had reimbursed the patients. The board then vacated its order and dismissed the complaint . After the case was settled, Lorrie Kruse, who believes that the board was too lenient, sent e-mail requests to several enforcement officials asking that more be done. Della Porta responded by suing Kruse for defamation , but the suit backfired after Kruse engaged the services of attorney Robert H. Buesing. In December 2013, Della Porta withdrew the lawsuit and agreed to pay an undisclosed sum in return for Kruse’s pledge that she would not sue him for malicious prosecution or other grounds related to the case [37,38].
How to Protect Yourself
I believe that the Sargenti method adds risk with no advantage over standard endodontic procedures. Its proponents have had more than 40 years to present adequate safety data to the FDA but have failed to do so. The filling material probably works well in most cases where it is used, but when things go wrong, the results can be horrendous. For that reason, I suggest avoiding it. Case reports indicate that some of Sargenti’s followers do not routinely disclose that the filling material they use contains paraformaldehyde and is not FDA-approved. If a general dentist invites you to have root canal therapy, ask how often the dentist performs root canal treatment and whether your case is complicated and should be referred to an endodontist. Also ask whether the Sargenti technique, N2, or any material that includes paraformaldehyde will be involved. Be wary of general dentists who say they never refer to an endodontist or who use Sargenti methodology.
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- Claudia and Robert Megaro vs Dominic Cicero. Superior Court of New Jersey, Warren County, Docket No. WRN-L-226-04, filed May 1, 2004.
- Deposition of Dominic John Cicero, Feb 9, 2005, pp 40-42.
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- Final order vacating previous final order and dismissing case. Florida Board of Dentistry Case No. 2009-05195, Sept 19, 2012.
- Kelley E. Dentist files suit to protect reputation. Vero Beach 32963, Oct 31, 2013.
- Della Porta RA. Release of Lorrie Hiller Kruse a/k/a Lorrie Kruse by Raymond A. Della Porta, Sr., DMD. Dec 9, 2013.
- Kruse L. Release of Raymond A. Della Porta, Sr, DMD by Lorrie Hiller Kruse a/k/a Lorrie Kruse. Dec 11, 2013.
This article was revised on May 1, 2018.