A. ElAyouti

The ability of root ZX apex locator to reduce the frequency of overestimated radiographic working length.

The aim of this in vitro study was to evaluate the ability of the Root ZX device to avoid instrumentation beyond the apical foramen in premolars after conventional working length radiography. Thirty extracted premolars with 43 root canals were subjected to radiographic and electronic working length determination. Radiographic working length determination resulted in overestimation in 51% of the root canals, although the measuring file tip was located to be 0 to 2 mm short of the radiographic apex. Electronic working length measurements with the Root ZX reduced the percentage of overestimation to 21%. In 6 root canals (14%), both radiographic and electronic working length measurements led to overestimation. It is concluded that complementing radiographic working length determination with electronic apex locator measurements may help to avoid overestimation beyond the apical foramen in premolars.

Efficiency of Hand and Rotary Instruments in Shaping Oval Root Canals

This study was designed to determine the efficiency of hand and rotary instruments in shaping oval root canals. Seventy-five oval canals were equally divided into three groups. The apical third was prepared with rotary LightSpeed instruments either to size 52.5 (mandibular incisors) or to size 57.5 (distal root of mandibular molars). The middle third with an oval cross-section was shaped with Hedström hand files using circumferential technique, with 6% taper rotary Hero files in a circumferential filing movement or with rotary LightSpeed instruments in a step-back technique. Instrumentation was performed under clinical conditions in a phantom head. The teeth were sectioned at two levels in the middle third of the root. An assembly technique allowed comparing the canal outline before and after instrumentation. The photographed root sections were superimposed and traced under a stereomicroscope. The ratio of prepared to unprepared canal outline was calculated for each section. The lowest values were observed in the LightSpeed group (mean: 0.42; 95% confidence interval (CI): 0.37; 0.47). Significantly higher values were recorded in the Hero group (mean: 0.58; 95% CI: 0.53; 0.64) and in the Hedström group (mean: 0.56; 95% CI: 0.49; 0.62). No instrumentation technique was capable of completely preparing dentin walls of oval root canals. Circumferential filing of the middle third of oval root canals with either 6% taper Hero files or conventional Hedström hand files gave comparable results.

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.

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.

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.

Increased Apical Enlargement Contributes to Excessive Dentin Removal in Curved Root Canals: A Stepwise Microcomputed Tomography Study

INTRODUCTION To determine whether increased apical enlargement would result in a complete preparation of curved canals and to progressively assess shaping quality using multiple microcomputed tomography (MCT) scans. METHODS Ninety root canals with a curvature of 25° to 50° were selected. Five MCT scans, 1 preoperative and 4 postoperative, were acquired from each canal. Canal preparation was performed up to size 50 using 3 techniques, nickel-titanium (NiTi) hand files, Mtwo (VDW, Munich, Germany), and ProTaper (Maillefer, Ballaigue, Switzerland), by experienced operators in a dental mannequin so as to simulate the clinical conditions. At a level of 1 mm short of the working length, 2 parameters were evaluated in each of the 4 postoperative acquisitions: the percentage of the prepared outline and the amount of dentin removed (the prepared area). RESULTS Statistically, there was no significant difference between the 3 systems used regarding the prepared outline. The maximum prepared outline was achieved by the use of NiTi hand files (63%; confidence interval [CI], 54%-73%), whereas Mtwo and ProTaper amounted to 58% (CI, 50%-66%) and 60% (CI, 51%-70%), respectively. In contrast, the dentin area removed by ProTaper was significantly higher than that of Mtwo and NiTi hand files. CONCLUSIONS Increased apical enlargement of curved canals did not result in a complete apical preparation, whereas it did lead to the unnecessary removal of dentin.

Homogeneity and adaptation of endodontic fillings in root canals with enlarged apical preparation

OBJECTIVE The aim was to compare the homogeneity and adaptation of endodontic fillings placed in root canals with wide apical preparation. STUDY DESIGN One hundred twenty root canals were prepared under simulated clinical conditions. The range of apical preparation size was 45 (narrow canals) to 60 (wide canals). The canals were filled using 4 techniques: Thermafil, GuttaFlow, apical cone, and vertical compaction. The root canals were sectioned at 5 levels. The adaptation and homogeneity of the filling were evaluated and statistically analyzed. RESULTS The percentage of canal outline in contact with the filling in the Thermafil group (91.3% [95% confidence interval (CI) 88.8%-93.6%]) was statistically significantly lower than in the other groups. No statistically significant differences were found between GuttaFlow (96.6% [95% CI 95.7%-97.5%]), apical cone (98.6% [95% CI 98.0%-99.3%]), and vertical compaction (98.1% [95% CI 96.5%-99.7%]). Similarly, the percentage of void area in Thermafil group (4.0% [95% CI 2.6%-5.3%]) was statistically significantly higher than in the other groups (GuttaFlow 1.4% [95% CI 0.1%-1.8%], apical cone 1.6% [95% CI 0.7%-2.4%], and vertical compaction 0.1% [95% CI 0.1%-1.8%]). CONCLUSIONS The tested filling techniques/materials provided similar high values for the homogeneity and adaptation to root canal walls after enlarged apical preparation, except for Thermafil at the most apical level.

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.

Neurosensory impairment of the mental nerve as a sequel of periapical periodontitis: Case report and review

Apical periodontitis of endodontic origin rarely leads to sensory impairment of the inferior alveolar or mental nerve. This article reviews and documents a clinical case of neurological disorder where paresthesia and hypesthesia of the mental nerve resulted as a sequel of apical periodontitis of a mandibular second premolar. The healing process and long-term results 3 years after conventional root canal treatment are presented.

Treatment of calcified root canals in elderly people: a clinical study about the accessibility, the time needed and the outcome with a three-year follow-up

OBJECTIVE Determination of accessibility, time needed and outcome of endodontic treatment of teeth with calcified root canals in a sample of elderly participants in a private practice limited to endodontics. BACKGROUND Due to demographic changes, gerodontology is becoming more and more important, also in the field of endodontology. Elderly patients can show up with severe calcifications of root canals. Root canal treatment, when needed, can be very challenging in these cases. Only few data exist about the treatment of calcified root canals and its outcome, especially in an elderly population. MATERIALS AND METHODS Forty-one participants (median age: 72 years) needing a root canal treatment were included. The total number of treated teeth was 41 with 114 negotiated root canals. A specialist limited to endodontics performed the treatment in a private practice. Outcome was assessed by applying the periapical index score on the basis of recall radiographs provided by the referring dentists. Likewise, time required to localise the root canals was measured. RESULTS All root canals have been detected using the operating microscope, and full working length could be established in 90% of the cases. Success rate was 80% after an observation time of 3 years. In three of five teeth, root canals could be localised within 15 min. CONCLUSION Calcified root canals of older people treated in this study were all accessible within a maximum of 60 min. The success rate after a follow-up of 3 years was 80%.