Allan Deutsch

Introduction

VER the last fifty years, endodontics has seen the advent of many new techniques and devices that have been aimed at making the procedure easier and increasing the success rate of the treatment.  Some have worked well; others appeared to work well when the academic literature was reviewed, but in clinical practice success was not apparent. ¹   As with any technique in dentistry, clinical success is the acid test. 
    Many investigators have reviewed the literature on endodontic success vs. failure and have reported similar ranges of results.  Pekruhn in 1986  reported on 15 studies.²  He found a failure range of 2.3 percent to 30 percent. This corresponds to a success range of 70 percent to 97.7 percent.  Friedman in 1997 reported on 37 success vs. failure studies done from 1956 to 1996.³   He found a reported success range for these studies of 59 percent to 98 percent.   Weiger et al. studied the literature and reported a success range between 70 percent and 90 percent.⁴   Hepworth and Friedman reviewed studies of orthograde retreatment and found a range of success of 70 percent to 90 percent.⁵
    Success for single-visit endodontic treatment falls in the high end of the ranges studied by these authors.  Pekruhn reported a failure rate of 5.2 percent or a success rate of 94.8 percent in his study on one-visit root canals. ²  Soltanoff in his single-visit study reported a success rate of 85 percent.⁶  Oliet reported a success rate of 89 percent for single visit endodontic treatment,⁷ and Jurcak et al. in their one-visit study on soldiers also reported a success rate of 89 percent.⁸
     Naturally, the optimum success rate, the one we all strive for, is 100 percent success.  Unfortunately, there are too many variables in treatment, materials, diagnosis, and reporting methods to make this a reality.  Certainly new endodontic techniques that report success rates in the high end of the ranges previously reported should be considered clinically successful treatments.
     Obturation of the root canal space has always been an arduous task with unpredictable results in two aspects.  One aspect is how to thoroughly fill the canal lumen and the other is how to accurately and repeatedly place the root canal filling to the anatomic apex of the root.  Poor results in either of these two critical areas can ultimately lead to endodontic failure.^6,7
    A new obturation technique, EZ-Fill epoxy resin root canal cement and bi-directional spiral system from Essential Dental Systems (S. Hackensack N.J.) has been developed.  This technique achieves the desired results in a predictable easy fashion.  The aim of this study is to evaluate completed EZ-Fill endodontic cases for a successful outcome over a six-month to two-year time period. 

Materials and Methods

HE TEST SAMPLE consisted of 145 patients seen in a private endodontic practice in New York, New York. Non-surgical root canal therapy was performed on 153 teeth in one or more visits during the time period from 1/1/97 to 12/31/97 by three endodontic practitioners. Each endodontic specialist had more than twenty years of experience in a “very New York City” endodontic practice. 
    The following patient factors were also collected: age; sex; whether or not the tooth was vital; if non-vital, whether there was PAR (periapical area of radiolucency); number of visits to complete treatment (1, 2, or more); radiographic findings; type of failure; fracture status; extraction status. 
    The instrumentation technique for the endodontic procedure was the same in all teeth studied.  All teeth were treated with a rubber dam in place using an aseptic technique. Access was achieved and the working length was determined using the Endex apex locator (Osada, Los Angeles, CA)  During instrumentation the canals were irrigated frequently with 2.5 percent sodium hypochlorite.  The apex was instrumented to a size #20 stainless steel .02 tapered instrument.  Next the canal was widened with a number 2 Peeso reamer, no closer than 3 mm from the apex.  Thereafter the step-back technique was used to taper the canal.  A size #25 stainless steel Flexo-reamer (Dentsply/Maillefer, Tulsa OK) was used 1 mm short of the apex.  Then a size #30 stainless steel flexoreamer was used 2 mm short of the apex.  Next a size #35 stainless steel flexoreamer was used 3 mm short of the apex.  Then a size #40 stainless steel flexoreamer was used 4 mm short of the apex and finally a size #45 stainless steel flexoreamer was used 5 mm short of the apex. 
    Once the canal had been grossly prepared, either an .06 or .08 nickel titanium file of greater taper (Dentsply, Tulsa OK) was used to give the final shape to the canal.  This sequence of instrumentation is known as the “Simplified Endodontic Technique” or S.E.T.^9-11  The canal was then filled with either a fine-medium or medium gutta-percha point. 
    The canal was obturated using the EZ-Fill system, which consists of a bi-directional spiral paste filler and epoxy root canal cement.  The cement is an epoxy resin based cement like AH-26 but much more radiopaque.  It is also very biocompatible.^9-11  The bi-directional spiral of this system ensures that the canal walls are covered with cement and that there is no or minimal cement past the apex.  This controlled coverage is achieved because the spirals at the coronal end of the instrument spin the cement down the shaft toward the apex while the spirals at the apical end spin the cement upward toward the coronal end.  Where they meet (about 3-4 mm from the apical end of the shaft), the cement is thrown out laterally (Figure 1).  A prefitted single gutta-percha point was placed to the apex.  The tapered shape of the canal lets the excess cement escape coronally.  The cement in the canal seals the apex and all lateral and accessory canals. ¹²  The excess gutta-percha was seared off, and the access cavity was sealed with either glass ionomer cement or zinc phosphate cement. 
    At the end of the appointment, the patient was given both the cardiac dosage of antibiotic and 600 mg of ibuprofen for pain management.  The patient was then instructed to return to his or her general dentist, who would restore the tooth. 

Clinical and Radiographic Examination

RECALL CARDS were sent and telephone reminders were made to 363 patients. We were able to recall and evaluate 153 treatments in this study. 
 At the recall examination, from six to twenty-four months after treatment, we recorded pain; tenderness to percussion, palpation, or both; fistula development; and swelling.  Radiographic examination, using the long cone technique with a Siemens Heliodent x-ray unit, was carried out using an x-ray film positioning device by Rinn (Rinn Corp., Elgin IL). 
 Success was defined as:
• On radiograph a preexisting lesion had gotten smaller or healed completely.
• On radiograph no new lesion had formed where there was no lesion before.
• The patient upon questioning at the recall examination was asymptomatic.
• The patient was functioning well with the tooth.
All radiographs were examined by a single endodontist, and patients were clinically examined at recall by the endodontist who did the treatment. 

Statistical Methods

THE FISHER EXACT TEST was used to determine whether outcome (success, non-success), was associated with sex, number of visits, vital status, and, among non-vital teeth, presence of PAR.  Due to the small number of unsuccessful outcomes, a multivariate analysis could not be carried out. 

Results

RECALL CARDS were sent and telephone reminders were made to 363 patients.  We were able to recall and evaluate 153 treatments in this study.  This was a recall rate of 42 percent.

Baseline Characteristics

MEAN AGE of the patients was 53 and ranged from 20 to 85.  There were 61 percent females and 39 percent males in the study.  There were 57.2 percent vital teeth and 42.8 percent nonvital teeth in the study.  Of the non-vital teeth, 66 percent did not have a PAR and 34 percent did have PAR. 

Outcomes

THE OVERALL TREATMENT estimated success rate was 94.1 percent.  This was found at the exact 95 percent confidence interval: 89.1 percent to 97.2 percent.  There was a frequency of 9 unsuccessful and 144 successful endodontic treatments.
    There was strongly no significant association between success rate and each of the following variables:
 

Therefore there was a 94.1 percent success rate regardless of whether treatment took one or more visits, whether the tooth was vital or nonvital, and whether the patient was male or female. 

Discussion

IT WAS STRONGLY FELT that clinical success was an important aspect of a successful outcome.  Success rates reported over the last twenty years have ranged from 78 percent to 95 percent. Our result of 94.1 percent success fits well within this range. Differences in the definition of success most probably would alter the overall result of each study.   However, it is difficult to determine by how much each study’s results would change.  Our feeling is that individual studies may change slightly, but the overall range would most likely be the same due to other variables. These other variables include the skill of operators, who and how many people review the x-rays and cases, the techniques used, the materials used, and the time frame of the recall exam.
    In this study, three endodontists who each have more than twenty years of experience in private practice treated all the patients.  This high level of clinical experience could possibly be one reason the success rate was on the high end of the scale.  In a study by Sjogren et al., undergraduates at the University of Umea did the endodontic therapy and had a 91 percent success rate. ¹³  We used one endodontist to read the x-rays and evaluate the patients clinically.  This helped reduce the variable of different opinions by different evaluators as described in the articles by Goldman and Seltzer.^14,15
    The authors tried to eliminate the variables of technique and materials in this study by using the same instrumentation technique and materials for each patient.  We followed the S.E.T. technique for instrumentation and used the EZ-Fill epoxy resin root canal cement and bi-directional spiral obturation technique with a single gutta-percha point.  Friedman et al. reported on a clinical study to assess the treatment results following endodontic therapy using a glass ionomer cement sealer (Ketac-Endo, ESPE Gmbh, Seefeld, Germany).¹⁶  They found a 78.3 percent success rate and concluded that their results were compatible with those found in the literature and that this supports the clinical use of Ketac-Endo as an acceptable endodontic sealer.
    In this study, EZ-Fill epoxy resin root canal cement (a derivative of AH 26 root canal cement) was used; Figure 5B illustrates complete resorption of excess cement after a two-year recall. 
    The recall time frame shows the majority of patients at six months, with the next highest groups at one-year and two-year recalls. 
    We were able to recall and evaluate 153 treatments out of 363 in this study.  This was a recall rate of 42 percent.  This correlates well with a mean recall rate of 43 percent for other studies as reported by Pekruhn.³
    In agreement with other studies, there was strongly no significant association between success rate and:
      • the number of visits
      • vitality
      • patient sex
    Whether the tooth was treated in one visit or in more than one visit did not affect the success rate.  Teeth treated in one visit were equally as successful as teeth treated in more than one visit.  Whether the tooth was vital or nonvital did not affect the success rate, and whether the patient was male or female did not affect the success rate in this study.
    Interestingly, in a study by Vire of 116 extracted endodontically treated teeth, failure that led to extraction of these teeth occurred due to endodontic causes in only 8.6 percent of the population. ¹⁷ 

Conclusions

A SUCCESS RATE of 94.1 percent was found for this study using the EZ-Fill bi-directional spiral and epoxy resin root canal cement to obturate the canals.  This correlates very well with reported success rates of between 78 percent and 95 percent in other studies. 
    There was no significant association between success rate and each of the following variables: number of visits, sex, and vitality.  These results support the clinical use of the EZ-Fill obturation system as an acceptable endodontic technique and sealer.

References
 

1. Orstavik D, Kerekes K, Eriksen HM. Clinical performance of three endodontic sealers.  Endod Dent Traumatol 1987; 3:178-86.
2. Pekruhn, RB.  The Incidence of Failure Following Single-visit Endodontic Therapy. J Endodon 1986; 12:68-72.
3. Friedman S. Success and Failure of Initial Endodontic Therapy. Ontario Dentist 1997; 74:35-38.
4. Weiger R, Axmann-Kremar D, Lost C.  Prognosis of conventional root canal treatment reconsidered. Endod Dent Traumatol 1998; 14:1-9.
5. Hepworth M, Friedman S. Treatment Outcome of Surgical and Non-Surgical Management of Endodontic Failures. Journal of the Canadian Dental Association 1997; 63:364-371.
6. Soltanoff W. A Comparative Study of the Single-Visit and the Multiple-Visit Endodontic Procedure. J Endodon 1978; 4:278-281.
7. Oliet S, Single-visit Endodontics: A Clinical Study. J Endodon 1983; 9:147-152.
8. Jurcak JJ, Bellizzi R, Loushine R. Successful Single-Visit Endodontics During Operation Desert Shield. J Endodon 1993; 19:412-413.
9. Musikant BL, Cohen BI, Deutsch AS. Rethinking endodontics: Attaining total obturation of the root canal system with a simplified system. General Dentistry 1999; Jan-Feb: 73-82.
10. Seidman D. A General Dentist’s Viewpoint of Two New Endodontic Techniques. Compendium 1999; 20: 921-932.
11. Musikant BL, Cohen BI, Deutsch AS. Report of a Simplified Endodontic Technique. Compendium 1999; 20: 1088-1094.
12. Cohen BI, Pagnillo MK, Musikant BL, Deutsch AS. The evaluation of apical leakage for three endodontic fill systems. General Dentistry,1998; Nov/Dec:618-623.
13. Sjogren U, Hagglund B, Sundqvist G, and Wing K. Factors Affecting the Long-term Results of Endodontic Treatment. J Endodon 1990; 16:498-504.
14. Goldman M, Pearson AH, Darzenta N. Endodontic success: who’s reading the radiograph? Oral Surg 1972; 33:432-7.
15. Seltzer S, Bender IB, Smith J, Freidman I, Nazimov H. Endodontic failures-an analysis based on clinical, roentgenographic, and histologic findings. Part II. Oral Surg 1967; 23:517-30.
16. Friedman S, Lost C, Zarrabian M, Trope M. Evaluation of Success and Failure after Endodontic Therapy Using a Glass Ionomer Cement Sealer. J Endodon 1995; 21:384-390.
17. Vire DE. Failure of Endodontically Treated Teeth: Classification and Evaluation. J Endodon 1991; 17:338-342.

July-August 2001

FIGURE 1: The EZ-Fill bi-directional spiral spinning the cement laterally, not apically. 
 

FIGURE 2A: Tooth number 30, old root canal, under treated and underfilled.
 

FIGURE 2B: Root canal retreated and refilled using EZ-Fill obturation technique.
 

FIGURE 2C: Two-year recall showing complete healing.
 

FIGURE 3A: Typical vital case at completion. No periapical pathology.
 

FIGURE 3B: Six-month recall showed no pathology developed, healed and asymptomatic.
 

FIGURE 4A: Typical completion x-ray of a one-visit vital case using the EZ-Fill obturation technique.
 

FIGURE 4B: Nine-month recall x-ray showing intact lamina dura and healing.
 

FIGURE 4C: Two-year recall x-ray showing normal bone anatomy being maintained.
 

FIGURE 5A: Tooth number 15 showing excess EZ-Fill epoxy resin cement past the apex of the palatal canal.
 

FIGURE 5B: Two-year recall x-ray showing complete resorption of cement and healing.