Development of a New In Vitro Methodology to Simulate Internal Root Resorption

Quality of different obturation techniques to fill perforating internal root resorption: a micro-computed tomographic study

BACKGROUND

This study aimed to assess the quality of various obturation techniques to fill perforation caused by internal root resorption using Micro-computed Tomography.

METHODS

Cone-beam computed tomography images of a maxillary central incisor tooth with perforating internal resorptive defect were used to create a 3D printed model of the affected tooth. The replicas were divided into four groups based on the obturation technique used. The techniques included Group 1: a polydimethylsiloxane-based sealer (GuttaFlow-2) with gutta-percha. Group 2: same as Group 1 except for using a pre-mixed Bioceramic-based sealer (NeoSEALER Flo). Group 3: the defect was filled entirely using the NeoSealer Flo Bioceramic-based sealer. Group 4: the samples were obturated using the warm vertical compaction technique with a resin-based sealer (ADSeal). The resin models were then scanned a micro-computed scanner to evaluate the percentage of voids in each group.

RESULTS

The results showed that NeoSEALER Flo groups had significantly the highest volume of voids while GuttaFlow-2 and warm vertical compaction groups had the lowest void volume.

CONCLUSIONS

GuttaFlow-2 and warm vertical compaction techniques performed best in filling the internal resorptive defect.

Influence of tube current and metal artifact reduction on the diagnosis of external cervical resorption in teeth adjacent to a dental implant in CBCT: an ex-vivo study

OBJECTIVES

This ex-vivo study aimed to assess the influence of tube current (mA) and metal artifact reduction (MAR) on the diagnosis of early external cervical resorption (EECR) in cone-beam computed tomography (CBCT) in the presence of an adjacent dental implant.

MATERIALS AND METHODS

Twenty-three single-rooted teeth were sectioned longitudinally and EECR was induced using a spherical drill and 5% nitric acid in 10 teeth. Each tooth was positioned in the socket of the lower right canine of a dry human mandible and CBCT scans were acquired using 90 kVp, voxel of 0.085 mm, field of view of 5 x 5 cm, and varying tube current (4, 8 or 12 mA), MAR (enabled or disabled) and implant conditions (with a zirconia implant in the socket of the lower right first premolar or without). Five oral radiologists evaluated the presence of EECR in a 5-point scale and the diagnostic values (area under the receiver operating characteristic curve - AUC, sensitivity, and specificity) were compared using multi-way Analysis of Variance (α = 0.05). Kappa test assessed intra-/inter-evaluator agreement.

RESULTS

The tube current only influenced the AUC values in the presence of the implant and when MAR disabled; in this case, 8 mA showed lower values (p<0.007). MAR did not influence the diagnostic values (p>0.05). In general, the presence of an implant reduced the AUC values (p<0.0001); sensitivity values with 8 mA and MAR disabled, and specificity values with 4 mA and MAR enabled and 8 mA regardless MAR were also decreased (p<0.0001).

CONCLUSIONS

Variations in tube current and MAR were unable to improve EECR detection, which was impaired by the presence of an adjacent implant.

CLINICAL RELEVANCE

Increasing tube current or activating MAR tool does not improve EECR diagnosis, which is hampered by the artifacts generated by dental implants.

Comparative Effectiveness of Different Er:YAG Laser-Activated Irrigation Systems on Removing Calcium Hydroxide from Simulated Internal Root Resorption Cavities at Different Root Levels

Objective: To investigate the effectiveness of Er:YAG laser-activated irrigation (LAI) with a short pulse duration for removing calcium hydroxide (CH) from simulated internal root resorption (IRR) cavities at three root levels. Background: Pulse duration is an important parameter during LAI, which ensures the efficiency of irradiation and the corresponding activation process. Short pulses in the range of a few microseconds enable rapid expansion and successive implosion of irrigants, resulting in distinct fluid movement. There have been few reports on CH removal efficacy from IRR cavities of different LAI systems, including those using short pulse duration. Methods: IRR cavities (1.6 mm diameter) were created at the apical, middle, and coronal root levels in 60 mandibular premolars and filled with a radiopaque CH paste. Samples were assigned to the following irrigation groups (n = 12, each): (1) LAI(P)-F, a prototype laser device that operates with short pulse duration (Morita Manufacturing) with a flat tip; (2) LAI(EA)-F, the ErwinAdverl laser device (Morita Manufacturing) with a flat tip; (3) LAI(EA)-T, the ErwinAdverl laser device with a tapered tip; (4) PIPS-T, the Lightwalker laser device (Fotona) with a tapered tip; and (5) SI, the syringe irrigation group. The laser tips were fixed at the canal entrance. The remaining CH volume and surface area were assessed in IRR cavities using micro-computed tomography and scanning electron microscopy, respectively. Data were statistically analyzed utilizing one-way analysis of variance and Tukey's test at 5% significance level. Results: The LAI(P)-F and PIPS-T groups exhibited the highest CH removal rates at three different levels (p < 0.05). The LAI(EA)-F group had a significantly better efficacy of CH removal compared with the LAI(EA)-T group at the middle level (p < 0.05). Conclusion: The LAI(P)-F and PIPS-T groups demonstrated superior efficiency in removing CH from simulated IRR cavities.

Evaluation of Different Techniques and Materials for Filling in 3-dimensional Printed Teeth Replicas with Perforating Internal Resorption by Means of Micro-Computed Tomography

INTRODUCTION

The aim of this study was to evaluate the filling ability of 2 obturation techniques in 3-dimensional (3D) printed teeth with perforating internal resorption (PIR).

METHODS

A maxillary central incisor was instrumented and scanned by micro-computed tomographic (micro-CT) imaging. The 3D model was exported in the stereolithographic format and, with the aid of OrtogOnBlender software (Cícero Moraes, Sinop, SP, Brazil), a PIR in the middle third of the root canal was designed. Thirty-two replicas were printed in surgical resin and distributed into 4 groups (n = 8) according to the obturation technique and the material used: 2 groups used the hybrid technique, 1 with Bio-C Sealer (BCS; Angelus, Londrina, PR, Brazil)/gutta-percha (GP; VDW GmbH, Munich, Germany) + Bio-C Repair (BCR; Angelus, Londrina, PR, Brazil) and the other with BioRoot (BR; Septodont, Saint Maur des Fosses, France)/gutta-percha (GP) + Biodentine (BD; Septodont, Saint Maur des Fosses, France), and 2 groups used the incremental technique, 1 with BCR and the other with BD. Postobturation micro-CT imaging was performed to measure the percentage volume of voids and laser confocal microscopy to measure the surface roughness (μm) of the repair cements. Data were compared using analysis of variance and Kruskal-Wallis tests.

RESULTS

Regarding the filling volume in the apical third, the BCS/GP + BCR (89.70 ± 5.15), BR/GP + BD (87.70 ± 8.43), and BCR (84.20 ± 9.00) groups showed the highest percentages compared with the BD group (69.70 ± 6.88) (P < .05). In the area of internal resorption, the BCS/GP + BCR (96.00 ± 2.64) and BCR (95.30 ± 2.93) groups showed the highest percentages compared with the BR/GP + BD group (91.50 ± 1.35) (P < .05). The BD group showed intermediate values that were sometimes similar to the BCS/GP + BCR and BCR groups and similar to the BR/GP + BD group (P > .05). Regarding the quality of the filling in the perforation area, the BCR group showed better results compared with the BD group (P < .001). Regarding roughness, the BCR group (1.66 ± 0.65) showed lower surface roughness compared with the BD group (2.51 ± 0.89) (P < .05).

CONCLUSIONS

The capacity and quality of the filling in teeth with PIR were superior with the incremental technique with BCR and the hybrid technique with BCS/GP + BCR.

Antimicrobial effectiveness of different irrigation activation techniques on teeth with artificial internal root resorption and contaminated with Enterococcus faecalis: a confocal laser scanning,icroscopy analysis

This study aimed to compare the antibacterial efficacy of standard needle irrigation (SNI), EDDY, passive ultrasonic irrigation (PUI), photon-induced photoacoustic streaming (PIPS), and shock wave enhanced emission photoacoustic streaming (SWEEPS) activation on the teeth with simulated internal root resorption (IRR) and contaminated with Enterococcus faecalis (E. faecalis) using confocal laser scanning microscopy (CLSM) analyses. A total of 79 human maxillary central incisors with a single canal were selected. The canals were accessed, and then, the roots were split in the bucco-lingual direction. Artificial IRR cavities (depth of 0.8 mm and a diameter of 1.6 mm) were prepared using round burs and 20% nitric acid in the middle region of the root halves. The root halves were reconstructed with cyanoacrylate glue, and the canals were contaminated with a culture of E. faecalis for 30 days. Root canal preparation was performed using the ProTaper Next rotary files up to X5 and 2.5% NaOCl irrigation. Teeth were randomly assigned to five groups according to the irrigation activation method (n = 15): SNI, EDDY, PUI, PIPS, and SWEEPS. The final irrigation procedures were performed using a total of 6 mL of 2.5% NaOCl for each tooth with an activation time of 3 × 30 s. The canals were stained with LIVE/DEAD BacLight dye and analyzed with CLSM to determine the percentages of dead bacteria in the biofilm. Two-way ANOVA and post hoc Tukey tests were used for statistical analysis (P < .05). None of the irrigation activation methods tested provided 100% bacterial elimination. There was no significant difference between the irrigation activation methods tested in terms of the percentage of dead bacteria (P > 0.05). In irrigation activation methods other than PIPS, there was no significant difference in the percentage of dead bacteria between the coronal, middle, and apical regions of the roots (P > 0.05). A higher percentage of dead bacteria was found in the middle region compared to the apical region in the PIPS (P < 0.05). Within the limitations of this study, SII, EDDY, PUI, PIPS, and SWEEPS have a similar antimicrobial effect on the teeth with IRR and contaminated with E. faecalis.

Exploring digital filters for internal root resorption: how can we improve the diagnosis of small lesions?

OBJECTIVES

This study aimed to evaluate the impact of enhancement filters in detecting small simulated internal root resorptions (IRR).

METHODS:

Forty-two extracted human teeth were sectioned, connected, and stored in a dry human jaw and X-rayed with photostimulable phosphor plates (PSPs), composing the control group (CG). In the middle-third of the root canals, IRR lesions were simulated using Da Silveira protocol. Later, the specimens were X-rayed to create the test group (TG). All images acquired were exported with seven enhancement filters plus the original image. Three examiners used a five-point Likert scale to evaluate the images regarding the presence/absence of IRR. Diagnostic efficacy was assessed from sensitivity and specificity results. Comparison among filters was performed by using receiver operating characteristic (ROC) curve analysis.

RESULTS:

Moderate values of Kappa interexaminer (0.403-0.620) and high values of Kappa intraexaminer (0.757-0.915) were observed. The best performance occurred in the CG (p < 0.05). Original images presented the greatest sensitivity and area under the ROC curve (0.595-0.750), while the Endo filter presented the greatest specificity (0.952). Inversion and Pseudo-3D images produced the greatest doubt in the diagnosis, significant for CG with the Pseudo-3D filter (p < 0.05).

CONCLUSIONS:

The Original and 'Endo' filters should be chosen as it offers greater diagnostic ability and allows more confidence during the evaluation.

Efficacy of Laser-Activated Irrigation and Conventional Techniques in Calcium Hydroxide Removal from Simulated Internal Resorption Cavities: Micro-CT Study

Objective: This study aimed to evaluate the effectiveness of different irrigant-activation techniques for eliminating calcium hydroxide from an internal root canal resorption cavity by using microcomputed tomography (micro-CT). Background: Several techniques and irrigants are inadequate for the complete removal of calcium hydroxide from an internal root resorption cavity. Recently, a few studies have investigated the effectiveness of various methods, but there has been no micro-CT study that compares the effectiveness of photon-induced photoacoustic streaming (PIPS) and shock wave enhanced emission photoacoustic streaming (SWEEPS) techniques. Methods: Seventy single-canal mandibular premolar teeth were selected and divided into seven groups (n = 10) according to the techniques to be used: syringe irrigation (SI), passive ultrasonic irrigation (PUI), EndoActivator (EA), XP-Endo finisher file (XP), Er,Cr:YSGG laser-activated irrigation, PIPS, and SWEEPS. The root canals were instrumented using a rotary system and divided vertically. Internal resorption cavities were created and standardized through diamond burs. Calcium hydroxide was placed into the root canal space. All specimens were evaluated using micro-CT in two different periods. The initial and residual calcium hydroxide volumes in the simulated cavities were calculated. Data were analyzed using a Kruskal-Wallis H test. Results: SWEEPS and PIPS were significantly more effective than EA, Er,Cr:YSGG, PUI, XP, and SI (p < 0.05). There was no significant difference between the SWEEPS and PIPS groups (p > 0.05). SI and XP showed the least effective activity (p < 0.05). Conclusions: The SWEEPS and PIPS techniques were superior to the EA, Er,Cr:YSGG, PUI, XP, and SI techniques. None of the techniques used entirely removed the calcium hydroxide from the resorption cavities.

Comparison of digital image displays performance in the detection of artificial internal root resorptions lesions

OBJECTIVE

To compare the diagnostic efficacy of different devices for visualizing digital images in detecting simulated internal root resorption (IRR).

METHODS

26 uniradicular human teeth were sectioned along its long axis and randomly divided into two groups. Then, they were submerged in hydrochloric acid (HCl) P.A 37% at different times to make two types of defects: Type 1 (2 hours), and type 2 (3 hours). Digital periapical radiographs were acquired in three moments: before section, after section and after immersion in acid. The images were evaluated on three different devices: 27-inch iMac Desktop, 8-inch Android Tablet, and 5.5-inch iPhone 8 Plus using a 5-point scale.

RESULTS

The sensitivity and accuracy values were higher with the use of the Android Tablet, for both types of defects. For the values of the area under ROC curve, higher results were observed with the Android Tablet and lower results with the iMac, showing a significant difference (p < 0.05) when comparing the use of the iMac with the Android Tablet and iPhone 8, for type 1 defects. When comparing the different devices, in the evaluation of images of type 2 defects, the values showed no statistical difference, regardless of the device evaluated (p > 0.05).

CONCLUSIONS

The size of the lesion interferes with the detection capacity in the image. However, the use of portable devices does not impair the diagnosis of IRR, regardless of size and the dental practioners may use different devices/display, under optimal viewing conditions, to detect IRR lesions, without jeopardizing the diagnostic ability.

Influence of the image file format of digital periapical radiographs on the diagnosis of external and internal root resorptions

OBJECTIVES

To evaluate the influence of different image file formats of digital radiographic images on the diagnosis of external (ERR) and internal root resorption (IRR).

MATERIALS AND METHODS

Thirty-four human teeth were selected. For ERR, 20 teeth were used (10 control and 10 with simulated ERR), and for IRR, 14 teeth were used (before and after IRR simulation). Digital periapical radiographs were acquired using the Digora Toto system and exported in four different image file formats: TIFF, BMP, PNG, and JPEG, totaling 192 radiographs. Five examiners evaluated the images using the JPEGView software and scored the detection of ERR or IRR on a 5-point scale. Sensitivity, specificity, accuracy, and the area under the ROC curve were obtained for the diagnosis of ERR and IRR in the different image file formats. Two-way ANOVA compared the diagnostic values between the file formats and the Kappa test assessed intra- and inter-examiner agreement. The significance level was set at 5% (α = 0.05).

RESULTS

The mean values of intra-examiner agreement were substantial (0.740) for ERR and almost perfect (0.836) for IRR and, inter-examiner was fair (0.263) and moderate (0.421), respectively. No statistically significant differences were found among the different file formats for the diagnostic values of ERR and IRR.

CONCLUSION

The file format of digital radiographs does not influence the diagnosis of ERR and IRR.

CLINICAL RELEVANCE

Digital radiographic images may be susceptible to computational factors; however, they can be stored in multiple file formats without affecting the diagnosis of dental root resorptions.

Diagnostic efficacy of different cone beam computed tomography scanning protocols in the detection of chemically simulated external root resorption

OBJECTIVES

The aim of this study was to evaluate the efficacy of different high-resolution cone beam computed tomography protocols in the diagnosis of chemically simulated external root resorption (ERR).

STUDY DESIGN

ERR was simulated in 3 sizes by using an acid decalcification protocol in the cervical, middle, and apical thirds of 30 single-rooted premolars. Four scans of each tooth were acquired with different voxel sizes: 0.080, 0.085, 0.120, and 0.133 mm. The images were analyzed by 2 blinded evaluators for the presence of ERR. The evaluation of diagnostic performance was based on receiver operating characteristic (ROC) curve analysis.

RESULTS

No statistically significant differences were found in the detection of ERR with regard to lesion sizes or the different root thirds. Areas under the ROC curve were 0.901, 0.892, 0.887, and 0.767 for voxel sizes of 0.080, 0.085, 0.120, and 0.133 mm, respectively. Voxel sizes of 0.080 and 0.085 mm presented significantly larger areas under the ROC curve compared with the voxel size of 0.133 mm. There were no statistically significant differences among the protocols with the use of voxel sizes of 0.080, 0.085, and 0.120 mm.

CONCLUSIONS

Cone beam computed tomography examinations with higher-resolution protocols demonstrated better performance in the diagnosis of ERR. Further investigations using simulations that more closely resemble the actual ERR process are warranted.

Evaluation of apically extruded debris during the removal of canal filling material using three different Ni-Ti systems and hand files in teeth with simulated apical root resorption

AIM

To compare the weight of apically extruded debris produced during the removal of root canal filling material using various files in extracted teeth with simulated apical root resorption.

METHODOLOGY

The root canals of one hundred and twenty extracted mandibular premolar teeth were prepared with Revo-S files and filled using a cold lateral compaction technique with gutta-percha and a resin-based sealer (AdSeal; Meta-Biomed, Cheongwon, Korea). Sixty teeth were randomly assigned to four control groups (hand file, ProTaper Universal retreatment file, D-RaCe retreatment file, and Reciproc file) for the removal of root canal filling material. The apical portion of the remaining 60 teeth was modified to simulate apical root resoption, and the teeth were then randomly divided into 4 experimental groups (using the same techniques as in the control groups) for the removal of root canal filling material. Apically extruded debris was collected into pre-weighed Eppendorf tubes and then dried. The mean weight of the apically extruded debris was assessed with an analytical balance to an accuracy of 10^-4  g. Data were analysed using two-way analysis of variance and a Tukey's post hoc test.

RESULTS

In the simulated apical root resorption groups, all file systems were associated with significantly more debris extrusion compared to the groups without simulated resorption (P < 0.05). The amount of apically extruded debris was greatest in the hand file groups compared with the other groups (P < 0.05). In the groups with simulated apical root resorption, the Reciproc system was associated with the least weight of apically extruded debris (P < 0.05), whereas there was no significant difference between the ProTaper Universal retreatment and D-RaCe files (P > 0.05). In the groups without simulated apical root resorption, there was no significant difference between Reciproc, ProTaper Universal retreatment and D-RaCe retreatment files (P> 0.05). The time required to remove the root canal filling material was as follows: hand file > ProTaper Universal retreatment = D-RaCe retreatment > Reciproc (P < 0.05).

CONCLUSIONS

The weight of apically extruded debris was significantly greater in teeth with simulated apical root resorption than in those teeth without simulated apical root resorption. Hand files were associated with significantly more apically extruded debris in all groups during removal of root canal filling material.

Diagnosis of external root resorption in teeth close and distant to zirconium implants: influence of acquisition parameters and artefacts produced during cone beam computed tomography

AIM

To assess the influence of artefacts, the metal artefact reduction (MAR) tool and kilovoltage (kVp) on the diagnosis of simulated external root resorption (ERR) in teeth close and distant to zirconium implants in cone beam computed tomography (CBCT) images.

METHODOLOGY

Cavities (0.62 mm in diameter and 0.19 mm deep) were created in the apical thirds of 12 roots on the buccal, lingual, distal or mesial surface; ten roots served as controls. The roots were randomly positioned in the first and second right and left premolar sockets of a dry human mandible, and a zirconium implant was placed in the socket of the first right molar. A ProMax 3D unit varying kVp (70, 80, or 90 kVp) and with the MAR tool activated or not was used to obtain CBCT scans. Five examiners evaluated all images to determine the area under the receiver operating characteristic (ROC) curve, sensitivity and specificity.

RESULTS

The ROC values and sensitivity were not affected by MAR or artefacts regardless of the distance to the implant (P > 0.05), whilst increasing kVp from 70 to 90 led to a significant increase in these values (P = 0.0202 and 0.0199, respectively). Specificity was not affected by the factors studied (P > 0.05).

CONCLUSIONS

Amongst the factors studied, only kVp influenced the diagnosis of simulated external root resorption in CBCT images. Increasing kVp from 70 to 90 improved the accuracy in diagnosing the simulated lesions.

Effect of brightness and contrast variation for detectability of root resorption lesions in digital intraoral radiographs

OBJECTIVES

To evaluate the performance of periapical radiography assessed under different radiographic brightness and contrast variations in the detection of simulated internal (IRR) and external (ERR) root resorption lesions. Additionally, observers' preferences related to image quality for these diagnostic tasks were evaluated.

METHODS

Thirty single-root teeth were divided into two groups (n = 15): IRR, in which lesions were simulated using mechanical and biochemical processes; and ERR, in which cavities standardized with drills of different sizes were performed on the root surfaces. Digital radiographs were obtained and subsequently adjusted in 4 additional combinations, resulting in 5 brightness/contrast variations (V1-V5). Five radiologists evaluated the radiographs. The observers' preference on the image quality was also recorded.

RESULTS

For both conditions, there were no differences in the accuracy and specificity between the five brightness/contrast variations (p > 0.05), but the sensitivity for ERR was significantly lower in V4 (+ 15% brightness/-15% contrast) in the large size (p < 0.05). The observers classified V2 (- 15% brightness/+15% contrast) as the "best" image quality for IRR and ERR evaluation.

CONCLUSIONS

For IRR and ERR lesions, brightness and contrast variation does not affect the diagnostic performance of digital intraoral radiography within the tested range. The observers prefer images with a reasonable decrease in brightness and increase in contrast.

CLINICAL RELEVANCE

Brightness and contrast enhancement tools are commonly applied in digital radiographic assessment. The use of these tools for detection of root resorptions can be applied according to the observer preference without influence on diagnostic accuracy.

Obturation quality of calcium silicate-based cements placed with different techniques in teeth with perforating internal root resorption: a micro-computed tomographic study

OBJECTIVES

To evaluate and compare the obturation quality of mineral trioxide aggregate (MTA) and Biodentine placed with hand condensation or indirect ultrasonic activation technique in teeth models simulating perforating internal root resorption (IRR) using micro-computed tomographic (micro-CT) imaging.

MATERIALS AND METHODS

Standardized models with perforating IRR cavities were created using 40 extracted single-rooted human teeth and randomly divided into four groups (n = 10). The specimens were obturated with either MTA or Biodentine and the placement technique applied was either hand condensation or indirect ultrasonic activation. Micro-CT scans were performed for the volumetric analysis of voids and filling materials in the resorption cavities and apical portion of the specimens. Data were analyzed using one-way analysis of variance and paired t test.

RESULTS

No significant difference was observed between the groups in terms of the percentage volume of filling materials (p > 0.05). The apical portion of the specimens significantly presented less percentage volume of filling materials than the resorption cavities in each group (p < 0.05).

CONCLUSIONS

No placement technique produced void-free fillings in teeth with perforating IRR. There was no significant difference between the obturation quality of Biodentine and MTA. The obturation quality in the apical portion of the root canals was inferior than that in the resorption cavities.

CLINICAL RELEVANCE

The obturation of the apical region of teeth with perforating IRR is challenging irrespective of the material type and placement technique.

Diagnostic accuracy of phosphor plate systems and conventional radiography in the detection of simulated internal root resorption

OBJECTIVE

To evaluate the performance of conventional radiography and photostimulable phosphor (PSP) plate in the detection of simulated internal root resorption (IRR) lesions in early stages.

MATERIALS AND METHODS

Twenty single-rooted teeth were X-rayed before and after having a simulated IRR early lesion. Three imaging systems were used: Kodak InSight dental film and two PSPs digital systems, Digora Optime and VistaScan. The digital images were displayed on a 20.1″ LCD monitor using the native software of each system, and the conventional radiographs were evaluated on a masked light box. Two radiologists were asked to indicate the presence or absence of IRR and, after two weeks, all images were re-evaluated. Cohen's kappa coefficient was calculated to assess intra- and interobserver agreement. The three imaging systems were compared using the Kruskal-Wallis test.

RESULTS

For interexaminer agreement, overall kappa values were 0.70, 0.65 and 0.70 for conventional film, Digora Optima and VistaScan, respectively. Both the conventional and digital radiography presented low sensitivity, specificity, accuracy, positive and negative predictive values with no significant difference between imaging systems (p = .0725).

CONCLUSIONS

The performance of conventional and PSP was similar in the detection of simulated IRR lesions in early stages with low accuracy.

CBCT-based volume of simulated root resorption - influence of FOV and voxel size

AIM

To examine the influence of the field of view (FOV) and voxel size on the measurement of the volume of simulated internal root resorption (IRR) lesions through cone-beam computed tomography (CBCT).

METHODOLOGY

Eleven single-rooted teeth with IRR simulated by acid demineralization were studied. CBCT images were acquired using large FOV (voxel sizes of 0.200, 0.250 and 0.300 mm) and limited FOV (voxel sizes of 0.076, 0.100 and 0.200 mm). The IRR volumes were calculated using the Dolphin(®) software. Volumetric measurements were validated using IRR silicone putty casts. The analysis of variance (anova) for randomized block design complemented with the Tukey's test was employed.

RESULTS

IRR volumes obtained using voxel sizes of 0.200 and 0.250 mm were similar (P > 0.05). However, both these values were significantly different from that obtained using the 0.300-mm voxel (P < 0.05). There was no significant difference between IRR volumes measured through voxel sizes of 0.076 and 0.100 mm (P > 0.05), but both differed significantly from that obtained through the 0.200-mm voxel (P < 0.05). There was no significant difference between the volumetric measurements of the 0.200-mm voxel images of the restricted and large FOV protocols. The mean volumes of the silicone casts were smaller than those calculated using a 0.200-mm voxel, but were similar to those obtained using voxel sizes of 0.076 and 0.300 mm.

CONCLUSIONS

Despite the FOV protocol, voxel size can influence measurement of simulated IRR volumes. The importance of standardization of CBCT image acquisition protocols is emphasized, especially during follow-up of an IRR lesion, to prevent misinterpretation of its extent, which can create a bias in clinical decisions.