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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 8  »  Periapical healing of endodontically treated teeth in one and two visits obturated in the presence or absence of detectable microorganisms
Periapical healing of endodontically treated teeth in one and two visits obturated in the presence or absence of detectable microorganisms
Materials and methods.



Patient selection.
Thirty-nine, patients with a non-contributory medical history, referred to the endodontic clinic of the Academic Centre for Dentistry in Amsterdam for root-canal treatment, were selected according to the following criteria. All the selected roots (17 incisors, 6 canines, 5 premolars and 11 distal roots of mandibular molars) had one canal, were asymptomatic, did not respond to sensitivity testing, had not received any endodontic treatment previously, and showed radiographic evidence of periapical bone loss. Maxillary molars were not included, because of radiographic overlaps hindering reproducible observation of changes in the periapical lesion size.
The mean age of the participants (19 females and 20 males) was 40 years and ranged from 19 to 86 years. The teeth were randomly divided into two treatment groups, every second patient was assigned to group 2. Group1teeth (n ј 21) were treated in one visit, group 2 teeth (n ј18) were treated in two visits with intracanal disinfection by calcium hydroxide for 4 weeks. The size of the periapical lesions was determined from the preoperative radiograph on a light box by measuring the largest diameter in millimeters with a ruler to an accuracy of 0.5 mm.

Microbial procedure.
All the canals were cultured at the start of treatment (S1, n ј 39); after instrumentation (S2, n ј 39); after removal of calcium hydroxide (S3, n ј18); and before obturation with gutta-percha (S4, n ј18) as described previously (Peters et al. 2002). After cleaning the tooth with pumice and isolation with rubber dam, the crown and the surrounding rubber dam were disinfected with 80% ethanol for 2 min. An access cavity was prepared with sterile high-speed diamond burs under irrigation with sterile saline. Before entering into the pulp chamber, the access cavity was disinfected again for 2 min with 80% ethanol. Sterility was checked by sampling with a cotton swab over the cavity surface and streaked on blood agar plates. All subsequent procedures were performed aseptically. The pulp chamber was accessed with burs and rinsed with Reduced Transport Fluid (RTF) (Syed & Loesche 1972) which was aspirated with suction tips. RTF was then introduced to the root canal with a syringe and 27-gauge needle. Care was taken not to over fill the canal. The canal was enlarged to a size 20 Hedstrom file to the estimated working length as calculated from the preoperative radiograph. Five sterile paper points were consecutively placed in the canal and left for 10 s (sample 1, S1). Then, these were placed in sterile tubes containing 1mL RTF and transferred to the laboratorywithin15 min for microbiological processing.
Ten-fold serial dilutions of the samples were prepared and100 mL of each dilution was inoculated on blood agar  plates supplemented with 5%horse blood,5 mg L  haemin and 1mg L  menadione. Plates were incubated anaerobically (80% N2, 10% H2, 10% CO2) at 37 8C for 7 days. After incubation, the total colony forming units (CFU) and the different colony types were counted using a stereomicroscope at 16x magnification (Zeiss, Oberkochen, Germany).
All the colony types were streaked to purity and incubated aerobically in air with 5% CO2 (BBL Gaspak CO2 systems, Becton Dickinson & Co., Cockeysville, MD, USA) as well as anaerobically to determine strict anaerobic and facultative anaerobic growth. Identification of the isolates was made on the basis of Gramstain, catalase activity and a commercially available identification kit - ATB rapid ID32A (Biomerieux SA, Lyon, France), for strict anaerobes and ATB rapid ID32Strep for facultative anaerobic cocci (Biomerieux SA).
In order to allow the slow-growing species to develop the blood agar plates with the total samples were kept under anaerobic conditions up to 14 days. The newly emerging colonies were also streaked to purity and were identified.

Root-canal procedure.
All procedures were performed by one endodontist. The working length (1mm from the radiographic apex) was checked with a radiograph after inserting a size15 K-file (Dentsply Maillefer, Ballaigues, Switzerland) in the canal to the estimated working length, or shorter if the attached electronic apex locator (Apit, Osada, Japan) indicated that the apical foramen had been reached. After the first microbiologic sample (S1), the canal was enlarged using Flexofiles (Dentsply Maillefer) with the modified double flare technique (Saunders & Saunders 1992), to a master apical file of at least size 35 (range 35-60). Each file was followed by irrigation of the canal with 2 mL sodium hypochlorite (2%) in a syringe with a 27-gauge needle. After preparation, the canal was irrigated with 5 mL sodium hypochlorite (2%). Then, inactivation of the sodium hypochlorite was accomplished with 5 mL sterile sodium thiosulphate, before a second microbiological sample (S2) was taken from the root canal in the same manner as the first sample.
After drying the canal with paper points, the teeth in group 1 (n ј 21) were obturated using the warm lateral- compaction technique with gutta-percha and AH- 26 sealer (Dentsply, Konstanz, Germany). At the end of the first visit all these teeth were restored. Teeth that did not receive a permanent restoration were restored with a temporary filling of two layers of Cavit (ESPE, Seefeld, Germany) and a glass ionomer restoration (Fuji-II, GC Corporation, Tokyo, Japan).
After drying the canal, the teeth in group 2 (n ј18) were dressed with a thick mix of calcium hydroxide (Merck, Darmstadt, Germany) in sterile saline. The calcium hydroxide slurry was inserted in the canal with a size 30 lentulo spiral (Dentsply Maillefer) and packed with the blunt end of a paper point. The access cavities in group 2 were filled with two layers of Cavit and a glass ionomer restoration. In the mandibular molars, the entrance of the distal canal was isolated with Cavit from the remaining pulp chamber in order to prevent contamination by microorganisms from the mesial canals (that had been instrumented but were not included in the study). A radiograph was taken to ensure proper placement of the calcium hydroxide in the canal.
The patients in group 2 returned after 4 weeks. The canal was aseptically accessed under rubber dam isolation and the calcium hydroxide removed with RTF and careful filing of the canal with the master apical file. Removal of calcium hydroxide from the canal was checked with an operating microscope at 16x (Zeiss, Oberkochen, Germany). A third bacteriological sample (S3) was taken as described previously. After sampling, the canal was rinsed with 5 mL of sodium hypochlorite (2%) andgently instrumented with the master apical file. After inactivation of the sodium hypochlorite with sodium thiosulphate, a fourth sample (S4) was taken from the root canal. The canal was dried and obturated withgutta-perchaandAH-26 sealer using the warm lateral compaction technique. After obturation of the canal, the tooth was restored in the same manner as the teeth in group1. A  final radiograph was taken using the paralleling technique with the aid of a beam guiding device (X-Act, Oral Diagnostic Systems, Amsterdam, the Netherlands), followed by control radiographs at 3, 6,12 and 24 months. If complete healing had not taken place at 24 months the patients returned annually up to 4.5 years. At the first follow-up appointment, all temporary restorations were replaced by a permanent restoration.

Evaluation.
Clinically, all the patients were free of symptoms and periodontal disease. The coronal restorations were of good quality during the entire follow-up period.
Three experienced endodontists who had not been involved in the treatment or follow-up appointments were asked to analyse the radiographs. Thirty  radiographs (not included in the study) were used for calibration of the evaluators.
One set of radiographs consisted of four to six radiographs from one patient, taken at different follow-up appointments and projected in an at-random sequence. Each radiograph only showed the root and apical bone structure, the rest of the radiograph was masked. The 39sets (one set of radiographs per patient) wereprojected on a screen in a dark room. The evaluators were asked to indicate the largest periapical radiolucency and the smallest periapical radiolucency of the set that was projected. Both images were given a periapical score from 1 to 5 (Table 1) (Reit & Grondahl 1983). The evaluators also indicated a score for the treatment outcome according to the criteria presented in Table 1 (A, B or C). After each evaluator had given his individual periapical scores and treatment outcome, a joint evaluation was made to reach a consensus.

Table 1. Definitions of periapical scores and treatment outcome.

Definitions of periapical scores and treatment outcome

Statistics.
A Student’s t-test for independent samples or chi-square test (when appropriate) was performed for differences between patient groups related to gender, age and the clinical parameters, such as the tooth type, size of radiolucency, preparation length, master apical file size and apical extent of the root-canal filling.
Differences amongst evaluators and consensus for periapical scores and treatment outcome were tested using the Friedman’s test for ordinal data.
The indicated largest and smallest periapical consensus scores were compared using the Wilcoxon’s signed ranks test to indicate if there was a significant reduction of the periapical bone lesions over time.
The time needed by each tooth included in the study to be assigned to the‘success’group was of interest. Ananalysis of event times that also accounts for the observation period of teeth associated with ‘failure’ was applied as described by Weiger et al. (1998). This approach also considers the individual time span within which the tooth under observation that is scored as B may show complete healing (A), although this time is cut off before the event occurs. The distribution of the event times for both treatment groups were separately calculated on the basis of the Kaplan-Meier method (Kaplan&Meier 1958) and presented as step functions. The log-rank test was applied for comparison of the two treatment groups.
A chi-squared test with Yate’s correction was performed for healing results of canals that showed bacterial growth at the time of obturation and canals that showed a negative culture.
For all tests, the P-values<0.05 were considered statistically significant. When no differences were found power statistics (power set at 80%) were conducted to determine the numbers required to find significant differences (P ј 0.05) between healing of teeth obturated with a positive canal culture and teeth obturated with a negative canal culture as well as differences in healing results of teeth treated in one and two visits.