Cone-beam computed tomographic scans in comparison with periapical radiographs for root canal length measurement: an in situ study.

INTRODUCTION: The primary aim of this study was to compare the precision of root canal length determination on cone-beam computed tomographic (CBCT) scans and periapical radiographs (PAs) with the actual root canal length. The secondary aim was to examine the influence of tooth type on root canal length measurements as assessed on CBCT scans and PAs. METHODS: In total, 40 root canals of 33 teeth (molars, premolars, canines, and incisors) out of 5 dentate maxillas of human cadavers were included. Root canal length measurement was performed by a consensus panel (2 examiners) on CBCT scans (3D Accuitomo 170; J Morita, Kyoto, Japan) and digital PAs. After straight-line access opening, a #15 file was fixated in every root canal at the length measured on CBCT scans. All teeth were extracted, and the root canal containing the file was uncovered. Measurements made on images taken with a digital camera (AxioCam; Carl Zeiss, Sliedrecht, The Netherlands) linked to a stereozoom microscope (Stemi SV6, Carl Zeiss) were used as the actual root canal length. RESULTS: When all roots were examined together, it was not clear which method is better for all types of teeth. For root canals of anterior teeth, there was no significant difference between the 2 methods. For root canals of posterior teeth, CBCT images gave results significantly closer to the actual root canal length in comparison with PAs (t value = -1.96; critical value is 1.74 with a significance level of 0.05). CONCLUSIONS: Root canal length measurements of posterior maxillary teeth were more accurate when assessed by CBCT images than PAs.

Volumetric changes in apical radiolucencies of endodontically treated teeth assessed by cone-beam computed tomography 1 year after orthograde retreatment.

INTRODUCTION: Cone-beam computed tomography (CBCT) allows us to assess in 3 dimensions the location and size of periapical radiolucencies. We aimed to assess by CBCT scans the volumetric changes of periapical radiolucencies in endodontically treated teeth 1 year after orthograde retreatment. METHODS: Forty-five root-filled teeth with persistent apical periodontitis requiring endodontic orthograde retreatment from 37 individuals were included in the study. The research protocol was approved by the VU University Medical Center Amsterdam ethics committee (2007/265), and the participants signed a letter of consent. We made 2 CBCT scans for every patient, the first one before retreatment and the second one a year later. Two observers measured independently the volume of radiolucencies on CBCT images by using the AMIRA software. The intraclass correlation coefficient was used to evaluate interobserver agreement, and the Wilcoxon signed rank test was used to assess pretreatment and post-treatment volume size. RESULTS: The intraclass correlation coefficients were 0.994 and 0.998 for the scans before retreatment and 1 year after, respectively. The recall rate was 78% for the teeth and 73% for the patients. The volumetric change in periapical radiolucencies 1 year after retreatment was statistically significant (z = -3.112, P < .005). The volume of periapical radiolucencies reduced in 20 teeth (57%), remained unchanged in 8 (23%), and increased in 7 (20%). CONCLUSIONS: One year after endodontic orthograde retreatment, the volume of periapical radiolucencies reduced significantly in 57% of the teeth.

Effect of post diameter and cement thickness on bond strength of fiber posts.

OBJECTIVE: This study evaluated the effects of different post diameter and oversized post spaces on the push-out bond strength of a fiber post to dentin. METHOD AND MATERIALS: Fifty extracted human maxillary central incisors and canines were divided into five groups and submitted to the push-out test (0.5 mm min-1). Groups 1, 2, and 3 were restored using a fiber post size that was identical to the drill size (sizes 1, 2, and 3, respectively), and groups 4 and 5 were both prepared with drill size 3, and restored using the size 2 and 1 fiber post, respectively. The fiber posts were cemented using self-adhesive dual-polymerized resin cement (RelyX Unicem). The data were analyzed using a one-way analysis of variance (ANOVA) and the Tukey test. RESULTS: There were no significant differences in the mean values for push-out bond strength between groups with different post diameters (P > .05). However, the push-out bond strengths were significantly different between groups with different cement thicknesses, and group 4 yielded the highest bond strength (11.7 ± 0.4 MPa). For all groups, the apical third had the lowest bond strength value (P < .05). CONCLUSION: The highest push-out bond strength values were obtained when one incremental oversized post space was used. Clinically, fiber post space has to provide an optimum cement thickness (around 120 µm) for adequate cementation.

Detection of vertical root fractures in vivo in endodontically treated teeth by cone-beam computed tomography scans.

INTRODUCTION: The presence of a vertical root fracture (VRF) in an endodontically treated tooth has an immense impact on the treatment's outcome. Early diagnosis of a VRF is imperative to avoid overtreatment and extensive bone loss. Our study aimed to examine the validity of 2 cone-beam computed tomography (CBCT) scanners in detecting VRFs in endodontically treated teeth in vivo. METHODS: Thirty-nine endodontically treated teeth suspected of VRFs from 39 patients were included. No fracture line was visible in periapical radiographs. Two limited-field-of-view scanners were used, the NewTom 3G and the 3D Accuitomo 170. Three observers evaluated the CBCT images independently and twice. The most frequently given score was used to calculate the validity of the CBCT systems. The findings of orthograde retreatment, endodontic microsurgery, or extraction were the gold standard. The intraobserver agreement (Cohen kappa) and the interclass correlation coefficients were calculated. RESULTS: The sensitivity, specificity, and accuracy for the NewTom 3G were 75%, 56%, and 68%, respectively, and for the 3D Accuitomo 170 they were 100%, 80%, and 93%, respectively. The positive predictive value and the negative predictive values were 75% and 55%, respectively, for NewTom 3G and 90% and 100%, respectively, for 3D Accuitomo 170. CONCLUSIONS: The results of our study support the use of 3D Accuitomo 170 for the detection of VRFs in endodontically treated teeth. They also suggest that the reproducibility and accuracy in VRF detection depend on the CBCT system used.

Comparison of five cone beam computed tomography systems for the detection of vertical root fractures.

INTRODUCTION: This study compared the accuracy of cone beam computed tomography (CBCT) scans made by five different systems in detecting vertical root fractures (VRFs). It also assessed the influence of the presence of root canal filling (RCF), CBCT slice orientation selection, and the type of tooth (premolar/molar) on detection accuracy. METHODS: Eighty endodontically prepared teeth were divided into four groups and placed in dry mandibles. The teeth in groups Fr-F and Fr-NF were artificially fractured; those in groups control-F and control-NF were not. Groups Fr-F and control-F were root filled. CBCT scans were made using five different commercial CBCT systems. Two observers evaluated images in axial, coronal, and sagittal reconstruction planes. RESULTS: There was a significant difference in detection accuracy among the five systems (p = 0.00001). The presence of RCF did not influence sensitivity (p = 0.16), but it reduced specificity (p = 0.003). Axial slices were significantly more accurate than sagittal and coronal slices (p = 0.0001) in detecting VRF in all systems. Significantly more VRFs were detected among molars than premolars (p = 0.0001). CONCLUSIONS: RCF presence reduced specificity in all systems (p = 0.003) but did not influence accuracy (p = 0.79) except in one system (p = 0.012). Axial slices were the most accurate in detecting VRFs (p = 0.0001).

Percentages of gutta-percha-filled canal area observed after increased apical enlargement.

INTRODUCTION: Increased apical enlargement might be achieved with S-ApeX files. However, S-ApeX preparations exhibit a small taper, which might hinder the performance of the root filling. The aim of this study was to compare the percentage of gutta-percha-filled canal areas (PGCA) in root canals after preparation with GT and S-ApeX instruments. METHODS: Four groups of maxillary lateral incisors (n = 20) were root canal treated. Canals were prepared with S-ApeX files to size 60 in 2 groups or with a GT system to size 30 taper 0.06 in other groups. Canals were filled with gutta-percha and AH26 by using a lateral compaction (LC) technique or a combined lateral and vertical compaction (LCVC) technique. Roots were then sectioned 2, 4, 6, and 8 mm from the apex. The area of the canal and gutta-percha was measured in each section, and the PGCA was calculated. RESULTS: The overall PGCA in the S-ApeX/LC group was significantly lower than that in other groups (analysis of variance, P = .001). The average PGCA values were 97.6%, 99.3%, and 98.5% for the GT/LC, S-ApeX/LCVC, and GT/LCVC groups, respectively. The differences between these groups were not statistically significant (analysis of variance, P = .21). CONCLUSIONS: A combined lateral and vertical compaction technique achieved comparable PGCA in canals prepared in maxillary lateral incisors by using S-ApeX or GT instruments.

Detection of vertical root fractures in endodontically treated teeth by a cone beam computed tomography scan.

Our aim was to compare the accuracy of cone beam computed tomography (CBCT) scans and periapical radiographs (PRs) in detecting vertical root fractures (VRFs) and to assess the influence of root canal filling (RCF) on fracture visibility. Eighty teeth were endodontically prepared and divided into four groups. The teeth in groups A and B were artificially fractured, and teeth in groups C and D were not. Groups A and C were root filled. Four observers evaluated the CBCT scans and PR images. Sensitivity and specificity for VRF detection of CBCT were 79.4% and 92.5% and for PR were 37.1% and 95%, respectively. The specificity of CBCT was reduced (p = 0.032) by the presence of RCF, but its overall accuracy was not influenced (p = 0.654). Both the sensitivity (p = 0.006) and overall accuracy (p = 0.008) of PRs were reduced by the presence of RCF. The results showed an overall higher accuracy for CBCT (0.86) scans than PRs (0.66) for detecting VRF.

Comparison of growth and susceptibility to sodium hypochlorite of mono- and dual-species biofilms of Fusobacterium nucleatum and Peptostreptococcus (micromonas) micros.

This study compared growth and susceptibility to different concentrations of sodium hypochlorite (NaOCl) of mono- and dual-species biofilms of Fusobacterium nucleatum or Peptostreptococcus micros in vitro at 24 hours or 96 hours. A Mann-Whitney U test revealed that although at 24 hours dual-species biofilms had similar viable counts to those of monospecies biofilms (p > 0.001), they were more resistant to NaOCl (p < 0.001). At 96 hours, both microorganisms had higher viable counts and were more resistant to NaOCl in dual-species biofilms than in monospecies biofilms of the same microorganism (p < 0.001). As the age of the biofilms increased, so did their resistance to NaOCl. Mixed-species biofilms of F. nucleatum and P. micros showed a time-dependent synergy in growth and resistance to NaOCl.