Effect of Voxel Size on Detection of External Root Resorption Defects Using Cone Beam Computed Tomography

Exceptional bone remodeling over composite restoration in the management of external root resorption: A case report

A 65-year-old Caucasian male was referred to an endodontic specialist practice in a private clinic in December 2019 for the management of an asymptomatic, radiolucent lesion located at the cervical level of the distal root of his right lower first molar, noticed during a routine periapical radiograph. After an accurate evaluation with cone-beam computed tomography (CBCT), the subgingival lesion was diagnosed as a supracrestal external cervical resorption (ECR), with a circumferential spread ⩽90°, confined to dentine without pulp involvement. The lesion was treated with the following sequence: (1) a full flap accessed the ECR, (2) the granulomatous tissue was removed from the root area, (3) the cavity was refreshed and filled with a well-refined and polished resin composite, (4) the flap was sutured at the cemento-enamel junction. A mandibular CBCT scan was performed before treatment, right after treatment, and 3 years postoperatively. Compared to the 3-year posttreatment CBCT scan, the immediate posttreatment one, revealed the absence of bone loss and an unexpected coronal bone remodeling with new bone formation over the treated lesion.

Introducing a new auto edge detection technique capable of revealing cervical root resorption in CBCT scans with pronounced metallic artifacts

Cervical resorption is a serious threat to the longevity of the teeth. In this study, the Canny edge-detection algorithm was applied on CBCT images to compare the accuracy of original and Canny views for diagnosing cervical resorption in endodontically treated teeth. Intracanal metallic posts were inserted in 60 extracted teeth being randomly divided into three groups: control, 0.5 mm, and 1 mm cervical resorption. CBCT scans of the teeth were presented to three observers in both original and Canny formats with the accuracy being determined by receiver operating characteristic (ROC) analysis. The DeLong test was used for paired comparisons with the significance level set at 0.05. The highest accuracy belonged to Canny images in 1 mm resorption, followed by Canny images in 0.5 mm resorption, original images in 1 mm resorption, and original images in 0.5 mm resorption, respectively. The Canny images were significantly more accurate in the diagnosis of 0.5 mm (p < 0.001) and 1 mm (p = 0.009) resorption. Application of the Canny edge-detection algorithm could be suggested as a new technique for facilitating the diagnosis of cervical resorption in teeth that are negatively affected by metallic artifacts.

External root resorption and rapid maxillary expansion in the short-term: a CBCT comparative study between tooth-borne and bone-borne appliances, using 3D imaging digital technology

BACKGROUND

The aim of the study was to analyze and compare external root resorption (ERR) in patients treated with tooth-borne (TB) and bone-borne (BB) rapid maxillary expansion (RME).

METHODS

The sample included 40 subjects who received tooth-borne RME (TB group, average age: 13.1 ± 1.08 years) or bone-borne RME (BB group, average age: 14.5 ± 1.11 years) and Cone-beam computed tomography (CBCT) scans before treatment (T0) and after 3-month of retention (T1). A specific 3D Imaging technology was used to generate 3D models of posterior dentition (M1 = maxillary first molars, P2 = second premolars, P1 = first premolar) and calculate volumetric data (mean and percentage values) and shape changes, the latter obtained from deviation analysis between the radicular models at different time points. Evaluation of radicular length changes was performed for each tooth. Data were statistically analysed to perform intra-timing and inter-groups comparisons.

RESULTS

A significant reduction of radicular volume and length was found in posterior dentition in both groups (p < 0.05), and the M1 (volume) and its palatal root (length) were mostly involved in this response. No differences were found between M1, P1 and P2 (p > 0.05) when volumetric changes were calculated as percentage of the total volume. Deviation analysis revealed that the radicular areas mostly affected by shape change were the apex and bucco-medial side. The amount of ERR was significantly greater in TB group compared to BB group.

CONCLUSIONS

BB-RME treatment could reduce the amount of ERR at the post-expansion stage.

External root resorption (ERR) and rapid maxillary expansion (RME) at post-retention stage: a comparison between tooth-borne and bone-borne RME

BACKGROUND

The study aimed to compare external root resorption (ERR) three-dimensionally in subjects treated with tooth-borne (TB) versus bone-borne (BB) rapid maxillary expansion (RME). Forty subjects who received tooth-borne RME (TB group, average age 13.3 years ± 1.10 years) or bone-borne RME (BB group, average age 14.7 ± 1.15 years) were assessed using CBCT imaging before treatment (T0) and after a 6-month retention period (T1). 3D reconstructions of the radicular anatomy of maxillary first molars (M1), first and second premolars (P1 and P2) were generated to calculate volumetric (mean and percentage values) and shape changes (deviation analysis of the radicular models) obtained at each time point. 2D assessment of radicular length changes was also performed for each tooth. Data were statistically analyzed to perform intra-group (different teeth) and inter-group comparisons.

RESULTS

In both groups, all the investigated teeth showed a significant reduction in radicular volume and length (p < 0.05), with the first molars being the teeth most affected by the resorption process (volume and palatal root length). When volumetric radicular changes were calculated as a percentage of the pre-treatment volumes, no differences were found among the investigated teeth (p > 0.05). Based on the deviation analysis from radicular models superimposition, the areas most affected by shape change were the apex and bucco-medial root surface. Overall, the amount of ERR was significantly greater in the TB group (mm³: M1 = 17.03, P1 = 6.42, P2 = 5.26) compared to the BB group (mm³: M1 = 3.11, P1 = 1.04, P2 = 1.24).

CONCLUSIONS

Despite the statistical significance, the difference in the amount of ERR of the posterior maxillary dentition between TB-RME and BB-RME remains clinically questionable.

Evaluation of a metal artifact reduction algorithm and an adaptive image noise optimization filter in the estimation of peri-implant fenestration defects using cone beam computed tomography: an in-vitro study

OBJECTIVE

The aim of this study is to assess the effects of metal artifact reduction (MAR) and adaptive image noise enhancer (AINO) in CBCT imaging on the detection accuracy of artificially created fenestration defects in proximity to titanium and zirconium implants in sheep jaw.

METHODS

Six zirconium and 10 titanium implants were planted on mandibular jaws of three sheep, and artificial defects were created. All images were obtained with a standard voxel size (0.150 mm³) and with 4 scan modes: (1) without MAR/without AINO; (2) with MAR/without AINO; (3) without MAR/with AINO; and (4) with MAR/with AINO during CBCT scanning. A total of 60 CBCT scans were produced.

RESULTS

For all types of implants, intra- and inter-observer kappa values were the highest for MAR filter. The scan mode of with MAR filter was found to have the highest area under the curve (AUC), whereas the scan mode of without both MAR and AINO filters was found to have the lowest AUC values with statistical significance (p ≤ 0.05). Titanium implants were found to have higher AUC values than zirconium (p ≤ 0.05).

CONCLUSION

Both MAR module and AINO filters enhance the accuracy of the detection of peri-implant fenestrations; however, the use of MAR filter solely can be recommended for detection of peri-implant fenestrations.

Influence of Voxel Size and Filter Application in Detecting Second Mesiobuccal Canals in Cone-beam Computed Tomographic Images

INTRODUCTION

This study assessed the influence of voxel size and filter application in detecting second mesiobuccal (MB2) canals in cone-beam computed tomographic (CBCT) images.

METHODS

Using the OP300 CBCT system (Instrumentarium, Tuusula, Finland) and 3 voxel size protocols (80 μm, 125 μm, and 200 μm), we scanned 40 first molars: 20 with an MB2 canal and 20 without. All molars received silver palladium pins on the palatal root, whereas the non-MB2 molars were also filled with gutta-percha. Five oral radiologists assessed the presence of an MB2 canal under 3 filter application conditions: without filter, with sharpen 1 × filter, and with sharpen 2 × filter. Intra- and interobserver reproducibility was evaluated using the weighted kappa index. We compared the area under the receiver operating characteristic curves with SPSS Statistics v.20.0 (IBM Corp, Armonk, NY) using 2-way analysis of variance and the Tukey post hoc test with 5% significance level.

RESULTS

Our analysis found median intra- and interobserver agreement values of 0.70 and 0.56, respectively. The 80-μm voxel with sharpen 1 × filter image group had the highest sensitivity, accuracy, and negative predictive values. As for specificity and positive predictive, the 80-μm voxel group without filter application presented the highest values. The areas under the receiver operating characteristic curve were higher in the 80-μm groups than in the 125-μm and 200-μm voxel size groups (P < .05). We found no differences among the filters used (P = .22) or for the filter-voxel size interactions (P = .88).

CONCLUSIONS

A smaller voxel size increased the accuracy in detecting MB2 canals, whereas the enhancement filters did not.

Evaluation of pulp cavity/chamber changes after tooth-borne and bone-borne rapid maxillary expansions: a CBCT study using surface-based superimposition and deviation analysis

OBJECTIVES

To compare volume and shape changes of pulp chamber of maxillary posterior teeth between tooth-borne and bone-borne maxillary expansions in adolescents.

MATERIALS AND METHODS

This study included 36 adolescents with bilateral maxillary crossbite who received tooth-borne rapid maxillary expansion (TB group, average age 14.4 years) or bone-borne rapid maxillary expansion (BB group, average age 14.7 years). Cone beam computed tomography (CBCT) was taken before treatment (T1) and after a 6-month retention period (T2). Volumetric and shape changes of pulp chamber of maxillary first molars and premolars were detected by referring to a specific 3D digital technology involving deviation analysis of T1/T2 CBCT-derived models of pulp chamber. Student's t tests were used to (1) compare T1 and T2 volumes of pulp chambers in TB and BB groups and (2) assess differences between the two groups in the post-treatment volumetric changes and in the percentage of matching of 3D pulp models.

RESULTS

All investigated teeth showed a reduction of pulp volume, being this difference significant in both TB (p < 0.0001) and BB (p < 0.0001) groups. The volumetric reduction was greater in the TB group; also, subjects in the TB group showed a lower percentage of matching between T1 and T2 pulp models (p < 0.0001). The area most affected by shape change was that of pulp horns.

CONCLUSIONS

TB expander could induce a higher volumetric reduction of pulp chamber of posterior teeth compared with BB expander, in the short term.

CLINICAL RELEVANCE

The present findings add new information concerning the effects of RME protocols on pulp tissue.

Imaging diagnosis of external root resorption in replanted permanent teeth

The present study aimed to evaluate the performance of cone beam computed tomography (CBCT) and digital periapical radiographs (PR) in diagnosing external root resorption (ERR) in human permanent teeth replanted after traumatic avulsion. The samples comprised 39 permanent maxillary incisors replanted after traumatic avulsion. Digital PR and CBCT images were taken from each tooth and independently examined by 2 calibrated examiners to assess the ERR activity regarding type and extension. The degrees of agreement between both imaging examinations were determined by the mean global agreement index using SPSS software. The two imaging examinations diverged greatly in the diagnosis of the type of ERR since CBCT identified more cases as inflammatory ERR and PR as replacement ERR. A discordance level of 69.2% was observed between the two methods in the diagnosis of the type of ERR when CBCT for mesial and distal (MD) surfaces was considered and 61.5% when CBCT for mesial, distal, buccal and lingual (MD/BL) was considered. Likewise, CBCT and PR differed regarding the ERR index. PR examinations classified most cases as moderate or severe (69.2%), while CBCT examinations classified more cases as mild either in the MD surfaces analysis (41.4%) or in the analysis of the MD-BL surfaces (51.3%). In conclusion, the present results highlight a discrepancy between CBCT and digital PR performance in the diagnosis of different types and extent of ERR in replanted teeth.

Influence of tooth position within the field of view on the intensity of cone-beam computed tomographic imaging artifacts when assessing teeth restored with various intracanal materials

Purpose

This study aimed to quantify the influence of tooth position within the field-of-view (FOV) on cone-beam computed tomography (CBCT) imaging artifacts' intensity when assessing teeth restored with various intracanal materials.

Materials and Methods

Seventy single-rooted teeth were divided into 7 groups (10 teeth per group): NiCr post (NC), AgPd post (AP), metal core fiberglass post (MCFG), fiberglass post (FG), anatomical fiberglass post (AFG), fiberglass post cemented with core build-up cement (FGCo), and anatomical fiberglass post cemented with core build-up cement (AFGCo). All posts were cemented using a regular dual-curing resin cement (Allcem), except FGCo and AFGCo which were cemented with a core build-up dual-curing resin cement (AllcemCore). Each tooth was scanned on a CS9000 in 5 positions within the FOV: a central position, anterior horizontal peripheral, peripheral superior, peripheral inferior, and posterior horizontal peripheral position. Hyperdense, hypodense, remaining teeth areas and ROI areas were quantitatively analyzed using ImageJ software.

Results

Posterior horizontal peripheral position increased the intensity of artifacts on FGCo and AFGCo post groups (P<0.05), and specifically the hypodense artifact intensity on FG and AFG post groups (P<0.05). NC and AP groups presented greater intensity of artifacts than any other post groups (P<0.05).

Conclusion

Artifact intensity increases in the presence of high atomic number materials and when the object is not centered within the FOV. The impact of positioning within the FOV on artifact was greater for fiberglass posts cemented with core build-up dual-curing cement than for metal posts and fiberglass posts cemented with regular dual-curing cement.

Evaluation of a metal artifact reduction algorithm and an optimization filter in the estimation of peri-implant dehiscence defects by using cone beam computed tomography: an in-vitro study

OBJECTIVES

The aim of this study was to assess the effect of a metal artifact reduction (MAR) algorithm and the adaptive image noise optimizer (AINO) optimization filter in the detection of peri-implant dehiscences with cone beam computed tomography (CBCT).

STUDY DESIGN

Nine implants (3 zirconium, 3 titanium, and 3 zirconium-titanium) were placed in 3 sheep heads. Dehiscences were created on the buccal and lingual/palatal surfaces. A total of 9 defects and 9 controls with no defects were evaluated by 3 observers. Each sheep head was scanned 5 times with 4 scan modes; (1) without MAR/without AINO; (2) with MAR/without AINO; (3) without MAR/with AINO; and (4) with MAR/with AINO. Receiver operating characteristic analysis and weighted kappa coefficients were used to calculate diagnostic efficacy and intra- and interobserver agreements for each implant type and scan mode.

RESULTS

For all implant types, dehiscences were most accurately detected when both MAR and AINO were applied (P ≤ .045). Detection of dehiscences was more accurate with titanium implants (P ≤ .040). There were no significant differences in agreement among and between the observers.

CONCLUSIONS

The use of both MAR and AINO enhanced the detection accuracy of artificially created dehiscences in proximity to implants. Their combined use is recommended for detecting peri-implant dehiscences.

Outcome of orthodontic treatment in subjects with periodontal disease. Part III: a CBCT study of external apical root resorption

Background

No evidence is present on the risk for external apical root resorption (EARR) during orthodontic treatment (OT) of adult patients with periodontal disease.

Aim

To examine EARR after OT in subjects with periodontal disease and to analyse how intrusion and change in inclination of the most proclined maxillary incisors influence EARR.

Methods

The study included 50 patients with periodontal disease. Sub-gingival debridement by ultrasonic instrumentation supplemented with hand instruments was performed by experienced dental hygienist after baseline examination for all patients. For the control group, final periodontal treatment (PT) was performed before orthodontic tooth movement. For the test group patients, final PT was performed after levelling and alignment phases were finished, before the active space closure with elastic chain and/or inter-arch elastic traction for sagittal correction was started. OT was performed with a straight-wire appliance. Micro-implants or implants were used for posterior anchorage. Cone beam computed tomography examinations were performed before and after OT. EARR of all single-rooted teeth were measured. EARR of the most proclined maxillary incisor was related to intrusion and change in inclination angle.

Results

EARR after OT was observed in median 80.7 per cent (interquartile range 22.02) of single-rooted teeth [mean 1.2 (standard deviation 0.44) mm]. In 82.3 per cent of teeth, EARR was 2 mm or less. Severe EARR was found in 8 per cent of patients and five maxillary incisors (less than 1 per cent of all teeth). The amount of intrusion and change in inclination angle of the most proclined maxillary central incisor influenced the extent of EARR. Mean EARR was significantly higher when OT lasted more than 18 months (P = 0.02).

Conclusions

OT in conjunction with PT in periodontal patients resulted in EARR in 81 per cent of all single-rooted teeth. Intrusion and change in inclination angle of the most proclined maxillary central incisor influenced the extent of EARR, as did longer OT.

Comparison of cone-beam computed tomography with bitewing radiography for detection of periodontal bone loss and assessment of effects of different voxel resolutions: an in vitro study

OBJECTIVE

The aim of the study was to compare intraoral radiographs and CBCT images for detection of horizontal periodontal bone loss, and to investigate the diagnostic effect of different voxel resolutions in CBCT imaging.

METHODS

A total of 240 sites with horizontal bone loss were measured on the buccal, lingual, mesial, and distal surfaces of 60 posterior teeth in four maxillary and six mandibular bones obtained from cadavers (dry skulls). Direct measurements on the dry skulls were accepted as the gold standard values. Measurements on CBCT images at two different voxel resolutions (0.250 and 0.160 mm³) and intraoral bitewing radiographs were compared with one another and with the gold standard values.

RESULTS

The measurements on the CBCT images at two voxel resolutions and bitewing radiographs did not differ significantly (p > 0.05) from the direct measurements on the dry skulls. No significant difference was found between the bitewing radiographs and CBCT images for measurements in the mesial and distal regions (p > 0.05). There was no significant difference between the measurements on the buccal and lingual surfaces at the two different voxel resolutions (p > 0.05).

CONCLUSIONS

CBCT scans are recommended for evaluation of buccal and lingual bone loss to avoid intraoral radiographs that exceed routine examination of interproximal alveolar bone loss. Furthermore, instead of basing the voxel size on the required CBCT scans, it is recommended to select the smallest possible field of view to reduce the dose of radiation.

The effect of varying cone beam computed tomography image resolution and field-of-view centralization on effective radiation dose

OBJECTIVES

To investigate changes in the effective radiation dose (E) in relation to variations in voxel (VOX) size settings and the field-of-view (FOV) centralization. Methods: This cross-sectional dosimetry study used nanoDot OSLD dosimeters placed at 25 pre-determined sites in the head and neck slices of a RANDO male phantom to measure the absorbed radiation. The imaging scans took place at King Abdulaziz University Dental Hospital, Jeddah, Saudi Arabia between September 2016 and May 2017 using the i-CAT classic cone beam computed tomography (CBCT)  unit. Three VOX size setting were examined: 0.2 mm, 0.3 mm and 0.4 mm. The FOV was alternatively eccentrically centered on the maxillary and mandibular arches while holding all other factors constant. Effective radiation doses were calculated for each VOX size and FOV centralization setting. Results: An inverse and indirect relation was found between E and the VOX size setting with smaller VOX yielding higher E. CBCT scans centered on the mandible resulted in higher E than scans centered on the maxilla. Conclusion: Effective radiation doses are significantly affected by changes in VOX size settings and FOV centralization options. This reflects on the potential radiation risk to patients and highlights the importance of choosing exposure parameters carefully.