Changes in periapical status, quality of root fillings and estimated endodontic treatment need in a similar urban German population 20 years later.

OBJECTIVES: The study aimed at assessing, as primary objective, the periapical status and quality of root fillings, and, as secondary objective, the endodontic treatment need of a German urban population in a cross-sectional study 20 years after the first one. MATERIALS AND METHODS: Clinical and radiographic data of 353 patients were evaluated. Descriptive and regression analyses were performed and the endodontic treatment need was calculated. Results were compared with data from the year 1993. RESULTS: A total of 9269 teeth were examined (26.2 teeth per patient; 1993, 24.4), of which 337 teeth were root filled (3.6%; 1993, 2.7%). Prevalence of apical periodontitis in root-filled teeth was 34% (1993, 61%). Quality of root fillings was adequate in 117 cases (35%; 1993, 14%). Minimum endodontic treatment need was estimated with 1.6% (1993, 2.3%), including teeth with clinical symptoms. Considering symptomless teeth with apical periodontitis and poor quality of root filling, the treatment need was 2.9% (1993, 3.7%). Regression analysis identified quality of root filling as a significant factor for periapical health (p = 0.01, odds ratio 3.4×, 95% CI 1.9-6.3×), likewise the type of instrumentation. Teeth treated with rotary files had a significantly better outcome (p = 0.02, odds ratio 2.0×, 95% CI 1.1-3.7×). CONCLUSIONS: Quality of root fillings and the periapical status have improved over the last 20 years in Germany. However, there is still a need for an increase in quality of root canal treatment.

Evaluation of the accuracy of nine electronic apex locators by using Micro-CT.

AIM: To determine the accuracy of locating the apical constriction using apex locators. METHODOLOGY: Extracted teeth were micro-CT scanned preoperatively to localize the apical constriction. Electronic length measurements of 91 root canals were made using nine electronic apex locators (EAL) connected to a mounting model. Distances from the major foramen were recorded at each scale bar of the EALs, and a file was fixed in the canal at a position indicated by each EAL to be the apical constriction. A second micro-CT scan was conducted, and distances from the file tip to constriction and major foramen were calculated for each EAL. The accuracy of EALs was determined with a tolerance of 0.1, 0.25, 0.5 and 1 mm, and the 95% confidence interval was used to compare the EALs. A rank analysis was performed in which measurements beyond the major foramen were considered as inaccurate. RESULTS: Regardless of the type of teeth, there was no significant difference in the accuracy of determining the apical constriction and major foramen between the nine EALs within a tolerance of ±0.5 mm and 1 mm, but there was a significant difference for the tolerances of ±0.1 and 0.25 mm. The highest ranks close to the constriction (98% and 94%) and to the major foramen (86% and 73%) were observed in Dentaport ZX and Elements Diagnostic Unit, respectively. Overestimation of working length beyond the major foramen was observed in all EALs (5% to 71%) when the scale for the major foramen, as recommended by the manufacturers, was used. However, when the scale for the constriction was used, only 3% of the measurements were beyond the major foramen. CONCLUSION: Electronic apex locators were able to determine the apical constriction. Using EALs to determine the major foramen led to overestimation of the working length. Therefore, it may be recommended to use the EAL scale of the constriction.

Validity of longitudinal sections for determining the apical constriction.

AIM: To validate the use of longitudinal sections against cross sections using micro-CT for disclosing the topography and location of the apical constriction. METHODOLOGY: Seventy extracted human teeth with 117 completely developed roots were micro-CT scanned and reconstructed at a voxel size of 27 µm. The 3DSlicer program was used to navigate the longitudinal sections parallel to the long axis of the canal and also to rotate and tilt the views. Each root canal was evaluated in both mesio-distal and bucco-lingual planes. Constriction topographies were identified as described in the literature. In each canal, the number of different topographies detected was recorded. Further, serial cross-sectional analysis of the apical portion of the canal was performed. Reconstructed plots of canal areas were assessed to locate the constriction and determine its form. A descriptive analysis of both longitudinal and cross section methods was conducted. In each canal, the frequency of constriction forms was calculated in the mesio-distal or bucco-lingual aspects and the 99% confidence interval was computed. RESULTS: When both aspects of the longitudinal sections were pooled, all root canals had two or more topographies and consequently different locations of the apical constriction. In contrast, cross-sectional analysis constantly yielded one constriction form per canal. CONCLUSION: Compared to cross-sectional analysis, longitudinal sections of the root canal conveyed inconsistent results regarding the topography and the location of the apical constriction.

Reliability of a Fluorescence-aided Identification Technique (FIT) for detecting tooth-colored restorations: an ex vivo comparative study.

OBJECTIVE: The aim of the study was to compare the diagnostic predictive values of a Fluorescence-aided Identification Technique (FIT) with those of the conventional diagnostic method regarding the identification of resin composite restorations. MATERIALS AND METHODS: Twenty examiners, 10 students, and 10 dentists were asked to identify composite restorations in a full-mouth model using both the FIT (405-nm light source) and the conventional method in combination with a common diagnostic light source. Each dental examination was repeated three times to calculate inter-/intra-operator agreement, repeatability, and reproducibility using kappa statistics. Predictive values were calculated using a filling prevalence of 42 % and the sensitivity and specificity of each method. Pearson's test and the 99 % confidence interval (CI) were used for comparison. RESULTS: The sensitivity (97 %, CI 94-99 %) and specificity (100 %, CI 98-100 %) of the FIT were significantly higher than those of the conventional method (27 %, CI 21-31 %, and 65 %, CI 58-72 %, respectively). Consequently, the positive (100 %) and negative (98 %) predictive values of the FIT were significantly higher than those of the conventional method (35 and 55 %, respectively). As expressed by the kappa statistics, the repeatability (0.96) and reproducibility (0.95) of the FIT were significantly better than those of the conventional method (0.49, CI 0.42-0.56, and 0.34, CI 0.26-0.43, respectively). CONCLUSION: Compared to the conventional technique, the FIT was significantly more reliable as shown by higher sensitivity, specificity, repeatability, and reproducibility values. CLINICAL RELEVANCE: The FIT should be considered as a reliable and practicable alternative in contrast to the conventional method, which was hardly sufficient as a diagnostic procedure.

Accuracy of endodontic working length determination using cone beam computed tomography.

AIM: To evaluate the accuracy of endodontic working length (WL) measurements by cone beam computed tomography (CBCT). METHODOLOGY: Forty-two extracted human teeth were placed into three full jaw models. Preoperatively, CBCT scans of the models were performed (voxel size: 0.2 mm). Endodontic access cavities were prepared, and the coronal third of 70 root canals were pre-flared. The real WL was measured by inserting a K-file into the root canal until the tip was visible at the foramen, a silicon stopper was adjusted to the corresponding cusp tip, and the length was measured using a micrometer. CBCT WL was simply measured by tracing a line between the apical foramen and the corresponding cusp tip. When the foramen and cusp tip were not visible in one plane, the measurement was taken in two planes. To quantify measurement error, real and CBCT WLs were repeated four times by two experienced operators. Paired analysis for each variable was performed, and the mean of absolute differences and the corresponding 99% confidence intervals were calculated. The t-test was used for comparison. RESULTS: The coefficient of repeatability, reproducibility and interoperator agreement were <0.5 mm. CBCT measurements were accurate; the mean of absolute differences between CBCT and real WL was 0.41 mm (99% CI 0.31-0.52 mm). CONCLUSION: Using a simplified method, CBCT images of 0.2 mm voxel size can be used to accurately determine endodontic WL.

Antimicrobial effectiveness of intracanal medicaments on Enterococcus faecalis: chlorhexidine versus octenidine.

AIM: To determine the viability of Enterococcus faecalis in infected human root dentine in vitro after exposure to root canal medicaments based on chlorhexidine and octenidine. METHODOLOGY: Human root segments (n = 40) were infected with E. faecalis for 8 weeks. Root dentine samples (rd) collected at week 4 served as individual baseline values. At week 8, the root segments were randomly divided into four test groups (n = 10 each) for the placement of one of the following medicaments in the root canals: calcium hydroxide paste (CH), chlorhexidine gel (CHX-gel) (5.0%), chlorhexidine/gutta-percha points (CHX-GP) (active points(®) ; Roeko, Langenau, Germany) and octenidine gel (OCT-gel) (5.0%) followed by incubation for 4 weeks. The effect on E. faecalis viability was assessed by two fluorescent dyes (syto 9/propidium iodide) to determine the 'proportion of viable bacteria' (PVB%) and number of 'colony-forming units' (CFU). Mean values and 95% confidence intervals (CI) were calculated for PVB% and log CFU, and the difference between groups was established. RESULTS: Viable and dead bacterial cells were detected in all 'rd' samples at weeks 4 and 8. The treatment with CHX-gel, CHX-GP and OCT-gel resulted in significantly lower PVB% values with 15.4%, 3.5% and 0%, respectively. No growth (CFU) was recorded for these samples at week 12. When medicated by CH, the PVB% was increased without a corresponding change in CFUs. CONCLUSIONS: In contrast to calcium hydroxide, both CHX - and octenidine-based intracanal medicaments were effective in decreasing the viability of E. faecalis. OCT showed the most favourable results and may have potential as an endodontic medicament.

Ultrasonic monitoring of the effect of sodium hypochlorite on the elasticity of dentine.

AIM: To determine the change in ultrasonic velocity of dentine after the application of 5% NaOCl. METHODOLOGY: Twenty standardized plano-parallel dentine bars were divided into two groups. Dentine bars were wetted on only one surface. The test group (n = 10) was irrigated with 5% NaOCl, and the control group, (n = 10) with saline. Ultrasonic velocities before and after irrigation were compared to determine the change in the modulus of elasticity. Finally, dentine bars were loaded until failure in a 3-point bending test. Paired t-test and the mean of differences were used to assess the statistical significance between the groups. RESULTS: The mean ultrasonic velocity decreased by 1.4% after the application of NaOCl; no change was observed for saline. The mean velocity reduction of 49 m s⁻¹ was found to be highly significant (P = 0.004). The ultrasonically derived modulus of elasticity decreased by 2.6% compared to the initial value of 17.8 GPa. However, the observed reduction in elasticity derived from the 3-point bending test was not significant (P = 0.238). CONCLUSIONS: NaOCl reduced the ultrasonic velocity of dentine and the ultrasonically derived modulus of elasticity.

Influence of cusp coverage on the fracture resistance of premolars with endodontic access cavities.

AIM: To assess the influence of cusp reduction and coverage with composite resin on the fracture resistance of premolars with prepared access cavities. METHODOLOGY: Endodontic access cavities were prepared in 60 premolar teeth that were divided into four test groups: R1, R2, R3 and NR (n=15). In all test groups, MOD cavities were prepared and extended towards one of the cusps. The remaining cusp-wall thickness was: 1-1.5 mm in R1, 1.5-2 mm in R2 and 2-3 mm in both R3 and NR groups. In addition, in group R1, R2 and R3 the same cusp was reduced in height to 3.5 mm. Cuspal coverage and MOD restorations were performed using composite resin. Ten intact premolars served as positive controls and another ten MOD-prepared unrestored premolars as negative controls. Teeth were submitted to cyclic fatigue of 1.2 million cycles. A compressive load was applied 30° to the long axis of the teeth until fracture. Fracture loads were recorded and the means and the Confidence Intervals were compared. RESULTS: The mean fracture resistance of each of the cusp-reduced groups R1, R2 and R3 (603, 712 and 697 N, respectively) was significantly higher than the non-reduced cusp group (305 N) and was comparable to the intact-premolar group (653 N). CONCLUSIONS: Cusp reduction and coverage with composite resin significantly increased the fracture resistance of premolar teeth with MOD and endodontic access cavities.

A tactile method for canal length determination in teeth with open apices.

AIM: To present a tactile method for working length determination in teeth with open apices and to determine its accuracy and repeatability. METHODOLOGY: Ninety teeth with 129 root canals were prepared to create open apices. The correct working length (CWL) for each canal was determined by introducing a file into the root canal until it was visible at the apex. Consequently, the tactile working length (TWL) was determined by the 'Tactile Method' using a K-file that was bent at the tip. Two operators repeated the measurement once in each root canal. The accuracy of the TWL was determined by comparing the TWL with the CWL. The mean of the absolute differences and the corresponding 99% confidence interval (CI) were calculated. Both the repeatability and inter-operator agreement of the tactile method were determined by performing paired analysis of the differences between repeated measurements and the two operators. RESULTS: Overall, 97% (CI: 91-99) of the TWL were within 0.5 mm from the CWL, the mean of absolute differences was 0.1 mm (CI: 0.1-0.2). The maximum difference between repeated measurements was 0.2 mm and between the two operators was 0.6 mm. CONCLUSIONS: The tactile method may provide an accurate determination of canal length in teeth with open apices.

[Suggestion for a classification of odontalgias]. / Vorschlag einer Klassifikation der Odontalgien.

BACKGROUND: Toothache prevalence in the overall population is considerable. However, for clinical purposes, the classification schemes available do not appear to be sufficiently sophisticated. Moreover, not all known forms of dental pain are considered. A refined classification that meets current standards is therefore introduced. To facilitate diagnosis, the characteristic features of the various types of odontalgia are summarized. RESULTS: The new classification differentiates among seven different origins of pain: 1. dentinal pain (originating from the pulpal tissues), 2. pulpal pain (originating from the pulpal tissues), 3. periodontal pain, 4. alveolar-osseous pain, 5. atypical odontalgia, 6. heterotopic dental pain, 7. odontalgia associated with primary psychosocial factors. CONCLUSIONS: In our opinion, the proposed classification differentiates among the different forms of odontalgia more precisely than all previous ones. However, its viability and advantages over other available classification schemes still need to be verified in daily practice.

Efficacy of rotary instruments with greater taper in preparing oval root canals.

AIM: To compare the preparation quality of two rotary systems and NiTi-hand files in oval root canals, and to evaluate the effect of canal dimensions on the preparation. METHODOLOGY: Ninety roots with oval root canals were selected. The middle third was cross sectioned at two levels and photographed. The maximum and minimum diameters of the root and canal were recorded. Teeth were distributed in three groups (n = 30) using stratified randomization, and prepared under simulated clinical conditions with Mtwo, ProTaper, or NiTi-hand files. The pre- and post-preparation photographs were traced and superimposed, the thickness of dentine removed was measured and the ratio of prepared canal outline was calculated. The impact of preparation system and canal dimensions on the quality of the preparation was evaluated using regression analysis. RESULTS: With regards to the ratio of prepared canal outline, no statistical significant difference was found between Mtwo (0.75 [95%CI: 0.69; 0.81]) and ProTaper (0.75 [95%CI: 0.69; 0.80]), but both systems performed significantly better than NiTi-hand files (0.65 [95%CI: 0.60; 0.71]). In six root canals in Mtwo-group (20%), and eight root canals in ProTaper-group (27%), the minimal thickness of dentine-wall after preparation was less than 0.5 mm. In contrast to the maximum diameter of the root canal, the minimum diameter influenced the quality of the preparation (P = 0.0006). CONCLUSIONS: No instrumentation technique was able to circumferentially prepare the oval outline of root canals. Nevertheless, instruments with greater taper (ProTaper and Mtwo) were more efficient than NiTi- hand files, but this was, in some cases, at the expense of remaining dentine-wall thickness.

A simple mounting model for consistent determination of the accuracy and repeatability of apex locators.

AIM: To develop a precise and simple mounting model (MM) for evaluating apex locators and to compare the repeatability of the MM with a conventional visual method (VM). METHODOLOGY: Electronic working length determination was performed in 32 maxillary central incisors using two methods: (i) the MM method and (ii) a conventional VM. The MM utilizes a micrometer to determine the distance travelled by the measuring file during working length determination. In the VM, the length of the measuring file (representing the working length) is determined visually using a caliper and a microscope at 6x magnification. Each measurement was repeated once. The repeatability of each method was evaluated by calculating the coefficient of repeatability. RESULTS: The coefficient of repeatability, which includes 95% of the differences between repeated measurements, was 0.04 mm for MM compared with 0.9 mm for VM. The measurement error of MM was significantly lower than VM (0.02 and 0.4 mm respectively). There was a statistically significant difference between the means of absolute difference in repeated measurements: MM 0.01 mm (95% confidence interval (CI): 0.01; 0.02 mm) compared with VM 0.4 mm (95% CI: 0.3; 0.5 mm). CONCLUSION: The new MM had superior repeatability in comparison with the conventional method where visual interpretation is a source of inaccurate measurement.

Determining the apical terminus of root-end resected teeth using three modern apex locators: a comparative ex vivo study.

AIM: To assess ex vivo the accuracy of various electronic apex locators in locating the apical terminus of root-end resected teeth. METHODOLOGY: Ninety extracted human posterior teeth (182 root canals) were prepared to a minimum size of 40 and filled with gutta-percha and sealer. After resection of the apical 3 mm of the root, the root canal filling was removed using HERO rotary instruments. The size of the root canal at the apical terminus after removal of the filling ranged from size 50 to 90. The root canal length to the apical terminus was determined using 3 apex locators (Root ZX, Raypex4 and Apex Pointer). A new mounting model that utilized a micrometer was used to perform the measurements and to visually determine the actual position of the apical terminus. The frequency of locating the apical terminus and the corresponding 95% confidence interval (CI) were calculated. Additionally, the coefficient of repeatability of each apex locator and the limits of inter-operator agreement were determined. RESULTS: All apex locators showed an acceptable repeatability (0.02-0.03 mm coefficient of repeatability) and narrow limits of inter-operator agreement (+0.07 and -0.07 mm). The accuracy of determining the apical terminus within 1 mm in the root canal was as follows: Root ZX 90% (164/182 root-canals) [95%CI: 86-94%], Raypex4 74% (135/182 root-canals) [95%CI: 68-80%], and Apex Pointer 71% (129/182 root canals) [95%CI: 65-77%]. No over-instrumentation resulted when the Root ZX device was used. In contrast, using the Raypex4 or the Apex Pointer device resulted in over-instrumentation in 8 of 182 root canals (4%). CONCLUSIONS: Under the conditions of this study all three apex locators were able to detect the apical terminus of root-end resected teeth with an acceptable range. The Root ZX device was the most accurate without over-instrumentation of the root canals.

Preparation of curved root canals with rotary FlexMaster instruments compared to Lightspeed instruments and NiTi hand files.

AIM: To compare the recently introduced rotary FlexMaster instruments with Lightspeed instruments and NiTi hand files in preparing curved root canals. METHODOLOGY: Root canals of extracted molars were shaped with rotary FlexMaster instruments ('FM': n = 45), Lightspeed instruments ('LS': n = 46), and NiTi hand files (n = 45) using the balanced-force technique. The apical preparation size was 40. Root canal instrumentation was carried out in a phantom head under clinical conditions. A re-assembly technique allowed a comparison of the canal outline before and after preparation. Root sections 2.5 mm short of working length were used to calculate the percentage of prepared canal outline (= PPO) and the amount of root canal transportation. Loss of working length, fracture rate and time spent on complete preparation were also recorded. RESULTS: The highest PPO values were found in the LS group (mean = 63% [95% CI: 55%; 70%]). Although not statistically significant, lower PPO values were detected for FM instruments (mean = 55% [95% CI: 49%; 62%]) and for hand files (mean = 53% [95% CI: 47%; 59%]). The incidence of root canal transportation exceeding 0.1 mm was significantly lower in the LS group than in the FM group. Loss of working length of 0.5 mm occurred in five cases (LS group: 4x; FM group: 1x). Two LS instruments fractured. Half the time was needed for root canal preparation with FM instruments than with hand files. CONCLUSIONS: Rotary FM instruments are suitable for preparing curved root canals. They provided results similar to LS instruments with minimal risk of instrument fracture but increased risk of root canal transportation.

Vitality status of microorganisms in infected human root dentine.

AIM: This experimental study was initiated to establish a method for characterizing the vitality status of bacteria in infected human root dentine by differentiating between viable and dead microorganisms. METHODOLOGY: Twenty-four root segments of extracted human teeth were infected with either Streptococcus sanguinis or Enterococcus faecalis for 8 weeks. Baseline samples from root dentine (rd) were collected after 4 weeks. These were compared with samples taken at week 8 (control group: n = 12) and with samples collected at week 12 after calcium hydroxide treatment for four weeks (test group: n = 12). After marking viable and dead bacterial cells by two fluorescent dyes, the portion of viable bacteria (PVB) was determined, as well as the number of colony-forming units (CFU). RESULTS: Viable and dead bacteria were identified in all "rd" samples. PVBrd values were lower than PVB values of the bacterial suspension in the root canal lumen. In the control group, PVBrd and CFUrd did not markedly differ at week 4 and at week 8, regardless of the strain used. In the test group, viable but non-culturable sanguinis streptococci (mean PVBrd = 27%; CFUrd = 0) were detected, despite calcium hydroxide treatment. The viability of E. faecalis was not affected by calcium hydroxide. CONCLUSIONS: Fluorescence labelling of bacteria in human root dentine gives valuable additional information about their vitality status compared to the parameter CFU. The method may be suitable for following the fate of bacteria in dentinal tubules, for example in the presence of intracanal dressings.

Frequency of overinstrumentation with an acceptable radiographic working length.

The aim of this in vitro study was to determine how frequent a seemingly accurate working length ending radiographically 0 to 2 mm short of the radiographic apex resulted in an instrumentation beyond the apical foramen. Under simulated clinical conditions working lengths of 169 root canals were radiographically determined in 91 extracted teeth. In all cases the measuring files adjusted to the final working length (Iwork) were located 0 to 2 mm short of the radiographic apex. Iwork was subsequently compared with the actual reference length (Iref) representing the distance between the apical foramen and the coronal reference. Instrumentation beyond the apical foramen (Iwork > ref) occurred in premolars in 51% (95% confidence interval: 36%; 66%) of the cases, in molars in 22% (95% confidence interval: 14%; 30%), and in anterior teeth in no case. These results suggest that in premolars and molars a radiographically working length ending 0 to 2 mm short of the radiographic apex provides, more often than expected, a basis for unintentional overinstrumentation.

Influence of calcium hydroxide intracanal dressings on the prognosis of teeth with endodontically induced periapical lesions.

AIM: This prospective clinical study explored the influence of calcium hydroxide as an interappointment dressing on the healing of periapical lesions associated with pulpless teeth that had not been endodontically treated previously. This was achieved by comparing the prognosis after a two-visit root canal treatment with that following a one-visit treatment. METHODOLOGY: Seventy-three patients were recruited having one tooth with an endodontically induced lesion. Of these patients, 67 could be re-examined. Calcium hydroxide was placed in the instrumented root canals of 31 teeth for at least one week and the treatment finished at the second visit. Thirty-six teeth were root canal treated at one visit. The criteria for success were the absence of signs and symptoms indicating an acute phase of periapical periodontitis and radiographically a periodontal ligament space of normal width. Methods for event time analysis were used to evaluate and compare the prognosis of both treatment approaches. RESULTS: The probability that complete periapical healing will take place increased continuously with the length of the observation period. In both treatment groups the likelihood that the root canal treatment yields a success within an observation time of five years exceeded 90%. A statistically significant difference between the two treatment groups could not be detected. CONCLUSIONS: From a microbiological perspective, one-visit root canal treatment created favourable environmental conditions for periapical repair similar to the two-visit therapy when calcium hydroxide was used as antimicrobial dressing. One-visit root canal treatment is an acceptable alternative to two-visit treatment for pulpless teeth associated with an endodontically induced lesion.

An in vitro comparison of two modern apex locators.

Two apex locators were compared regarding their ability to accurately locate the apical constriction in the presence of various canal fluids at different meter readings. Forty-one root canals were filled with 1% NaOCl, 3% H2O2, and 0.9% NaCl, respectively. Electronic working length (EWL) measurements were recorded with the apex locators Root ZX (meter readings: "Apex", "0.5", and "1") and Apit (meter readings: "Apex" and "3"). The deviation of the EWL from the apical constriction was determined. The proportion of measurements within +/- 0.5 mm of the apical constriction ranged between 0.76 and 0.85 for Root ZX at the meter readings "Apex" and "0.5," regardless of the canal contents. Apit consistently displayed shorter measurement values than Root ZX and reached the highest proportions at the meter reading "Apex": 0.59 (1% NaOCl), 0.61 (3% H2O2), and 0.68 (0.9% NaCl). In the presence of NaOCl, Root ZX provides the more accurate EWL measurements at the meter reading "0.5" and "Apex."