The second option is extraction of the offending tooth. Afterward, the patient must deal with the morbidity of the loss of a potentially restorable permanent tooth. In addition to coping with the loss of a natural tooth, the patient generally is encouraged to replace the extracted tooth prosthetically to maintain the integrity of the dental arches. Although in most cases there are prosthetic options available to the patient, many of them are more expensive than maintaining the tooth and having it restored after endodontic therapy. Unfortunately, the patient often will focus on the high initial cost of endodontic therapy relative to extraction and elect for the latter purely for financial reasons. In many of these cases, the extracted tooth never is subsequently replaced, resulting in compromise of intra-arch and interarch integrity.

Because the vast majority of dental emergencies are unscheduled, the practitioner’s goal is to provide predictable, effective treatment for them in a minimal amount of time. In cases in which endodontic therapy is the treatment of choice and the symptomatic tooth has a vital pulp, a full pulpotomy has been proven to be effective in relieving pain 96 percent of the time.¹ The term "pulpotomy" denotes the removal of the portion of the pulp tissue that has undergone degenerative changes, leaving behind healthy and vital tissue. The rationale behind the removal of this inflamed tissue is that some sort of dressing can be placed on the remaining healthy and uninflamed pulp. Since it is difficult to determine accurately the depth to which to remove the inflamed tissue, by convention, in a full pulpotomy procedure, pulp is removed to the level of the cervical line or to the level of the root canal orifices.

After pulpotomy, the access preparation is filled with some type of restorative material in an attempt to prevent bacterial infection of the remaining root canal space. Kakehashi and colleagues² were the first to demonstrate that bacteria were the primary etiologic factor causing pathosis. Since then, several investigations have supported this finding.^3–5 It also has been shown in several studies that the success rate of endodontic therapy is considerably higher in teeth without periapical lesions than in those with lesions.^6–8 Considering the objectives of preventing apical periodontitis, or AP, while at the same time providing treatment in a timely fashion, it is desirable that the material provide an adequate bacterial seal and be relatively easy to place.

Intermediate restorative material (Caulk IRM, Dentsply Caulk, Milford, Del.) is a polymer-reinforced zinc oxide–eugenol, or ZOE, preparation that has been tested extensively and often is used as a provisional restorative material after pulp therapy. As a provisional restorative material, it has the advantages of being relatively inexpensive and easy to handle, while still providing adequate seal of the root canal space. The tight seal provided by IRM is well-documented in the literature,^9,10 but little is known about how long this material can remain intact intraorally. One study indicated that the seal provided by IRM begins to leak approximately three weeks after placement,¹¹ while the manufacturer recommends use for up to one year.

Conventional glass ionomer shows some promise as an alternative to ZOE-based restorative materials. Compared with ZOE, most glass ionomers also are relatively easy to place, and these products can have superior wear characteristics. Studies also have shown that glass ionomers perform well in preventing leakage.^12,13 Considering these characteristics, glass ionomer may serve as a better long-term interim restoration than IRM.

If natural teeth are maintained asymptomatically and without formation of AP for at least one year with either of these restorative methods, this type of therapy may serve as a viable option to patients who wish to save their teeth but cannot afford to do so.

We conducted a study to determine whether

– pulpotomy of a vital pulp would result in interim relief of pain;

– there was a difference between the incidence of AP when the tooth was restored with either ZOE alone or ZOE with a glass ionomer surface seal;

– there was a difference in the durability of restorations of ZOE alone and ZOE with a glass ionomer surface seal over six and 12 months.

	SUBJECTS, MATERIALS AND METHODS

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
We obtained approval for this project from the University of North Carolina at Chapel Hill School of Dentistry’s Committee on Investigations Involving Human Subjects. Patients who visited the University of North Carolina School of Dentistry’s Urgent Care Clinic for treatment were considered for this study. We accepted subjects for this study if they met the following criteria:

– they were between 18 and 65 years of age;

– the symptomatic tooth was diagnosed with irreversible pulpitis;

– the tooth was able to retain a direct intra-coronal restoration;

– treatment had not commenced on the tooth as a result of the presenting symptoms;

– no radiographic AP or severe marginal periodontitis was associated with the symptomatic tooth;

– the patient chose to have extraction exclusively for financial reasons.

We excluded subjects’ teeth from the study if

– the subject had a history of diabetes or any other condition that might compromise the pulp’s immune response;

– the subject had a medical condition that required long-term antibiotic therapy or antibiotic prophylaxis before treatment.

We recruited subjects over an 18-month period.

After the preliminary evaluation and diagnosis in the urgent care clinic, we gave prospective subjects the option of participation in this study if they expressed a desire to retain the problematic tooth but were unable to afford complete endodontic therapy. They had to pay for the emergency treatment and would get a refund at the end of the study period. After receiving a verbal explanation of the study design and objectives, patient/provider obligations and the potential risks involved, the patients reviewed and signed consent forms to indicate their agreement to participate in the study. Two clinicians (R.A.M. and E.O.D.) then performed a comprehensive clinical evaluation in an effort to identify the symptomatic tooth and develop a preoperative pulpal and periapical diagnosis. These clinicians performed the diagnostic examinations and provided all treatment.

The clinicians obtained preoperative periapical radiographs using standardized radiographic technique and individual bite-blocks attached to the beam-guiding device (XCP Bite-Blocks, Dentsply Rinn, Elgin, Ill.).

The clinicians performed a full pulpotomy at least to the level of the root canal orifice, but not exceeding three millimeters apical to the orifice, after caries excavation under rubber dam isolation. After pulpotomy, the clinicians restored each tooth with either IRM (Group I) or IRM base with conventional glass ionomer core (Fuji IX GP, GC America, Alsip, Ill.) (Group II) by random assignment with a coin toss.

After treatment, the clinicians obtained a standardized periapical radiograph with a custom bite block using vinyl polysiloxane bite registration material applied to a periapical radiograph holder bite block (XCP Bite-Blocks, Dentsply Rinn). The radiographs were taken with double-pack no. 2 Ultra-speed intraoral dental film (Eastman Kodak, Rochester, N.Y.) using an intraoral radiographic tube (Heliodent DS, Sirona Dental Systems GmbH, Bensheim, Germany). The radiographic unit was operated at 60 kilovolts and 7 milliamperes. The exposure time varied between .4 and .8 seconds, depending on the type of tooth.

The clinicians asked the subjects to contact them immediately if pain developed in the affected teeth. Unless a subject had an acute episode of pain, recall examinations for each tooth took place at six and 12 months to determine clinical and radiographic signs of AP and integrity of the restoration. At each recall appointment, the clinicians obtained a periapical radiograph using the custom bite block fabricated at the initial appointment to assess periapical status radiographically. They also evaluated the integrity of the restoration clinically and repaired it if necessary. Patients with pain were given the option to undergo either complete endodontic treatment or extraction. Those whose teeth remained asymptomatic after 12 months were strongly advised to have complete endodontic treatment done as soon as possible.

Image analysis. We analyzed radiographs using computerized densitometric ratio analysis (as described by Kerosuo and Ørstavik,¹⁴ Delano and colleagues¹⁵ and Pettiette and colleagues¹⁶) after digitization and registration of each set of radiographs, which consisted of immediate (baseline), six-month recall and 12-month recall postoperative radiographs. We digitized these as eight-bit depth (256 gray levels) images in which 0 = black and 255 = white. For each image set, we delineated and measured an area of likely AP formation and a proximate healthy and normal, or N, area (Figure). We then calculated the mean gray levels ratio of AP/N. In calculating mean change in gray-level ratios between baseline and recall postoperative images, we determined that unchanged and positive values ( 0) represented health and negative values ( < 0) represented the presence of AP. One of the investigators (E.O.D.) performed all radiographic analyses. Statistical significance was set at = .05.

View larger version (46K): [in this window] [in a new window]   Figure. Periapical image of one of the patients showing delineation of areas of interest. This was one of two patients who had two teeth recruited in the study. Tooth no. 18 was restored with an IRM base with glass ionomer core (Fuji IX GP, GC America, Alsip, Ill.) and no. 19 with Caulk IRM (Dentsply Caulk, Milford, Del.). N: Normal area. AP: Area of likely apical periodontitis formation.

	RESULTS

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

Interim pain relief. Of 73 teeth, we accounted for 52 (71 percent) at the six-month recall and 40 (55 percent) at the 12-month recall. Five (10 percent) of the 52 six-month recall teeth required additional endodontic therapy owing to continued acute pulpitis. The patients involved complained of continuous pain, and they received additional therapy as late as 45 days after initial treatment. These teeth were considered as "immediate failures" because of the fact that initial treatment failure was diagnosed before the first scheduled recall visit.

The distribution of teeth by group in relation to pain relief can be seen in Table 1.

We diagnosed an additional four teeth with acute pulpitis and/or AP after the six-month recall, when the patients came in with complaints of pain and swelling. We termed these teeth "late failures," since initial pulp therapy rendered the patient asymptomatic for at least six months. The immediate and late failures made up the nine teeth that became painful during the 12-month period. We found no statistical difference between groups with a two-tailed Fisher exact test (P = .48).

The overall success rate in pain prevention dropped from 90 percent at six months to 78 percent at 12 months, as shown in Table 1.

Radiographic assessment (AP). Our image analysis is exclusive of teeth in subjects who experienced pain, swelling or both that required definitive treatment before a recall. We defined radiographic success as a maintained periapical status indicated by densitometric analysis. The group distribution of recall images can be seen in Table 2.

Integrity of restoration. We made the evaluation of the wear characteristics of the two restorative groups on the basis of the observed need for repair or replacement of the restoration on or before the scheduled recall appointments. We noted defective restorations requiring repair of one tooth each in Group I and Group II at the six-month recall.

By 12 months, an additional six in Group I and three in Group II required repair, resulting in a restorative success rate of 68 percent for Group I and 78 percent for Group II, as seen in Table 3. ² analysis showed no statistical difference (P = .32) between groups at 12 months.

	DISCUSSION

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

Since chronic AP may be painless, we elected also to monitor the periapical status of the treated teeth radiographically by means of computerized image analysis. This has been shown to detect subtle osseous changes¹⁵ and is an objective and reliable means of assessing periapiacal osseous change^14,15 on the basis of histologic correlation.¹⁸ Only asymptomatic teeth were included in radiographic assessment, as those that had become painful had undergone further management. In such cases, the patient must be made aware that the absence of symptoms does not mean that the disease has been arrested, and that this may affect the prognosis of final endodontic treatment. If it is assumed that immediate and late failures in our study would have been so affected, we can predict that the incidence of a deteriorated periapical status would have increased at both recalls. At 12 months, the major contribution to failure in the sample came from Group I (Table 2); again, this may be attributed to the higher loss of coronal integrity among Group I than among Group II. At the 12-month recall, 32 percent of coronal restorations in Group I showed damage compared with 22 percent in Group II.

It may appear from a clinical perspective that after pulpotomy, a restoration of an IRM base with a Fuji IX core had superior extended wear characteristics compared with an IRM restoration alone. However, we did not observe a statistically significant difference between the two treatments.

	CONCLUSION

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
In conclusion, on the basis of our findings, either a restoration of an IRM base with a Fuji IX core or an IRM alone is adequate for periods of six months or 12 months after pulp therapy. These treatments appear to be viable alternatives to extraction for patients who wish to maintain a tooth with irreversible pulpitis but cannot afford the ideally recommended complete endodontic therapy at the time of diagnosis. Each of these alternative therapies should be presented to the patient as an interim form of management, the use of which should not exceed a period of 12 months. During the time that this alternative therapy offers, it is feasible that the patient’s financial situation may improve to the point at which he or she can continue treatment with complete endodontic therapy. Failure on the patient’s part to seek definitive therapy (that is, complete endodontic therapy and definitive restoration) after a period of 12 months may result in the inability to receive complete endodontic therapy in the future owing to dystrophic calcification of the pulp space or further breakdown of the coronal structures. However, we did not observe this in some of the cases we treated after the study period.

The hybrid restoration may appear to be more beneficial in the above-mentioned scenario as well as for teeth with immature root formation during apexogenesis and apexification procedures by providing a durable, low-maintenance, bacteria-tight seal for the duration of the treatment.