Do the tube current and metal artifact reduction influence the diagnosis of vertical root fracture in a tooth positioned in the vicinity of a zirconium implant? A CBCT study

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.

Impact of the spatial orientation of the patient's head, metal artifact reduction, and tube current on cone-beam computed tomography artifact expression adjacent to a dental implant: A laboratory study using a simulated surgical guide

Purpose

The aim of this study was to evaluate image artifacts in the vicinity of dental implants in cone-beam computed tomography (CBCT) scans obtained with different spatial orientations, tube current levels, and metal artifact reduction algorithm (MAR) conditions.

Materials and Methods

One dental implant and 2 tubes filled with a radiopaque solution were placed in the posterior region of a mandible using a surgical guide to ensure parallel alignment. CBCT scans were acquired with the mandible in 2 spatial orientations in relation to the X-ray projection plane (standard and modified) at 3 tube current levels: 5, 8, and 11 mA. CBCT scans were repeated without the implant and were reconstructed with and without MAR. The mean voxel and noise values of each tube were obtained and compared using multi-way analysis of variance and the Tukey test (α=0.05).

Results

Mean voxel values were significantly higher and noise values were significantly lower in the modified orientation than in the standard orientation (P<0.05). MAR activation and tube current levels did not show significant differences in most cases of the modified spatial orientation and in the absence of the dental implant (P>0.05).

Conclusion

Modifying the spatial orientation of the head increased brightness and reduced spatial orientation noise in adjacent regions of a dental implant, with no influence from the tube current level and MAR.

Effect of metal artefact reduction level on the assessment of dental implant positioning by cone-beam computed tomography

OBJECTIVES

This study evaluated the effect of metal artefact reduction (MAR) level and tube current on the assessment of dental implant positioning relative to the mandibular canal (MC) through cone-beam computed tomography (CBCT).

METHODS

Titanium dental implants were placed in dried mandibles at 0.5-mm superior to the MC (group 1/n = 8) and 0.5-mm inside the MC with perforation of the cortex (group 2/n = 10). CBCT scans were obtained with different levels of MAR (off, medium, and high) and 2 tube currents (4 and 8 mA). Four examiners analysed the images and scored the contact between the implant and the MC using a 5-point scale. Sensitivity, specificity, area under receiver operating characteristic curve (ROC), and frequency of scores were calculated. Data were compared with analysis of variance 2-way and Tukey's test and scores with Chi-square test.

RESULTS

Specificity and area under ROC curve decreased significantly when MAR level was high compared with MAR-medium and MAR-off. The frequency of score 3 (inconclusive) was the highest, and scores 1 and 5 (definitely no contact and definitely contact, respectively) were the lowest with MAR-high, regardless of the tube current. When MAR was off, there were higher frequencies of scores 1 and 5.

CONCLUSIONS

The level of MAR influences the assessment of the relationship between the dental implant and the MC. MAR-high led to lower diagnostic accuracy compared with MAR-medium and off.

ADVANCES IN KNOWLEDGE

This article shows that high level of MAR can interfere in the diagnostic of dental implant positioning relative to the MC, decreasing its accuracy.

Influence of an adjacent zirconium implant, tube current, and metal artifact reduction algorithm on horizontal root fracture diagnosis in cone beam computed tomography

OBJECTIVE

We evaluated the influence of an adjacent zirconium implant, tube current (mA), and a metal artifact reduction algorithm (MARA) on horizontal root fracture (HRF) diagnosis in cone beam computed tomography (CBCT).

STUDY DESIGN

Nineteen teeth (9 with HRF, 10 without) were individually placed in a human maxilla. Scan volumes were acquired without and with a zirconium implant adjacent to the tooth at settings of 4, 8, and 10 mA, with MARA disabled and enabled, using a 5×5 cm field of view, 0.085-mm voxel size, and 90 kV. Four maxillofacial radiologists individually assessed the scans. Diagnostic metrics were compared by multiway analysis of variance (α=5%). Inter- and intraexaminer agreements for HRF diagnosis were evaluated with the weighted kappa test.

RESULTS

Area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were significantly lower in the presence of the implant (P≤.005). AUC values were higher in scans obtained with 8 and 10 mA compared with 4 mA (P=0.010), but 10 mA without MARA was better with the implant present. MARA did not significantly influence outcomes (P≥0.240). Inter- and intraexaminer agreements ranged from moderate to almost perfect.

CONCLUSIONS

The presence of the zirconium implant impairs HRF detection. Settings of 8 or 10 mA improve HRF detection regardless MARA condition without the implant. With an adjacent implant, 10 mA without MARA is recommended to improve diagnostic performance.

Case report and literature review: autonomous robotic system assisted palatal implantation at an anterior teeth site compromised by periapical cyst

Background

Immediate implant placement (IIP), which preserves gingival height and papilla shape while simultaneously accelerating the implant treatment period, has become a popular method due to its commendable clinical outcomes. Nonetheless, deploying immediate implants demands specific preconditions concerning the remaining alveolar bone. This poses a challenge to the accuracy of implant surgery.

Case presentation

In this report, we present the case of a 60-year-old woman with a left upper anterior tooth crown dislodged for over a month. Cone beam computed tomography (CBCT) revealed the absence of a labial bone wall on tooth 22, a remaining 1 mm bone wall on the labial side of the root apex, and a 17.2 mm*8.9 mm*4.7 mm shadow in the periapical region of the root apices of teeth 21 and 22, with the narrowest width on the sagittal plane being approximately 5 mm. After the surgeon removed the cyst, they completed the subsequent implantation surgery using an autonomous robot in a challenging aesthetic area. This method circumvented the potential exposure of the screw thread on the labial implant surface, assured initial implant stability.

Conclusion

Five months after the operation, the dental crown was restored. The implant remained stable, with yielding notable clinical results. To the best of our knowledge, this clinical case is the first to report the feasibility and precision of immediate implantation in anterior teeth site with periapical cyst removal, performed by an autonomous robotic surgical system. Autonomous robots exhibit exceptional accuracy by accurately controlling axial and angular errors. It can improve the accuracy of implant surgery, which may become a key technology for changing implant surgery. However, further clinical trials are still needed to provide a basis for the rapid development of robotic surgery field.

Zirconia implants interfere with the evaluation of peri-implant bone defects in cone beam computed tomography (CBCT) images even with artifact reduction, a pilot study

OBJECTIVES

Three-dimensional cone beam computed tomography (CBCT) imaging can be considered, especially in patients with complicated peri-implantitis (PI). Artifacts induced by dense materials are the drawback of CBCT imaging and the peri-implant bone condition may not be assessed reliably because the artifacts are present in the same area. This pilot study investigates the performance of the artifact reduction algorithm (ARA) of the Planmeca Viso G7 CBCT device (Planmeca, Helsinki, Finland) with three different implant materials and imaging parameters.

METHODS

Three pairs of dental implants consisting of titanium, zirconia, and fiber reinforced composite (FRC) were set into a pig mandible. A vertical defect simulating peri-implantitis bone loss was made on the buccal side of one of each implant. The defect was identified and measured by two observers and compared to the actual dimensions. In addition, the bone structure and the marginal cortex visibility between the implants were estimated visually.

RESULTS

The bone defect and its dimensions with the zirconia implant could not be identified in any image with or without the metal artifact reduction algorithm. The bone defect of titanium and FRC implants were identified with all three imaging parameters or even without ARA. The interobserver agreement between the two observers was almost perfect for all categories analyzed.

CONCLUSION

Peri-implantitis defect of the zirconia implant and the peri-implant bone structure of the zirconia implants cannot be recognized reliably with any ARA levels, or any imaging parameters used with the Planmeca Viso G7. The need for ARA when imaging the peri-implant bone condition of the titanium and FRC implants may be unnecessary.

Does the shape of the field-of-view influence the magnitude of artefacts from high-density materials in cone-beam computed tomography?

OBJECTIVE

To compare cylindrical and convex triangular field-of-views (FOVs) concerning the magnitude of artefacts from high-density materials in cone-beam CT (CBCT).

METHODS AND MATERIALS

Cylinders of amalgam, chromium-cobalt, titanium, and zirconia were individually placed in the anterior and posterior regions of a polymethylmethacrylate phantom and scanned using cylindrical and convex triangular FOVs of the Veraview X800 CBCT device. Using the Image J software, 15 square regions of interest (ROIs) were placed in the axial reconstruction around the middle level of the cylinder and at distances of 0.5, 1.0, and 1.5 cm from the centre of the cylinder. Mean grey value and standard deviation of each ROI were averaged for each distance and subtracted from the values of a control ROI to calculate the magnitude of the artefacts by the grey value mean difference (GVMD) and grey value standard deviation (GVSD). Multiway analysis of variance with Tukey post-hoc test with a significance level of 5% evaluated the effect of the shape of the FOV, position inside the FOV, high-density material, and the distance of the artefact from the material.

RESULTS

The convex triangular FOV increased the GVSD for all materials in the anterior and posterior regions at 0.5 cm compared to the cylindrical FOV (p < 0.0001). The convex triangular FOV showed greater GVMD for chromium-cobalt and zirconium in the anterior region and all materials in the posterior region at all distances (p < 0.0001).

CONCLUSION

The FOV shape influences the magnitude of artefacts from high-density materials. The convex triangular FOV showed greater artefact magnitude with variability among the high-density materials, region in the FOV, and distance from the material.

Quantitative assessment of image artifacts from zygoma implants on CBCT scans using different exposure parameters

This study was aimed at quantifying artifacts from zygoma implants in cone-beam computed tomography (CBCT) images using different exposure parameters. Two cadaver heads, one with two zygoma implants on each side and the other for control, were scanned using 18 different exposure parameters. Quantitative analysis was performed to evaluate the hypodense and hyperdense artifact percentages calculated as the percentage of the area. Hyperdense artifacts and hypodense artifacts were detected, followed by the calculation of the hyperdense and hypodense artifact percentages in the image. In the qualitative analysis of the artifacts, the scores used were as follows: absence (0), moderate presence (1), or high presence (2) for hypodense halos, thin hypodense lines, and hyperdense lines. Artifact analysis was performed qualitatively and quantitatively using the post-hoc Tukey and Two-way ANOVA tests. As a result, in the qualitative analyses, zygoma implants showed a significant difference compared to the control group with regard to hyperdense and hypodense artifacts (p < 0.05). There was a significant difference between the means according to the FOV size arithmetic averages (p < 0.05). In terms of voxel size, the difference was found to be significant, where 400 microns showed the highest hypodense artifact while 200 microns showed the lowest hypodense artifact. In conclusion, hypodense and hyperdense artifacts were significantly higher in cadavers with zygoma implants than in controls. As FOV and voxel size increase, more hypodense artifacts are produced by zygoma implants so smaller FOV and voxel sizes should be used to prevent poor image quality of adjacent teeth.

Efficacy of low-dose cone beam computed tomography and metal artifact reduction tool for assessment of peri-implant bone defects: an in vitro study

BACKGROUND

Early accurate radiographic assessment of peri-implant bone condition is highly important to avoid excessive loss of supporting bone and implant failure. Cone beam computed tomography (CBCT) is the radiographic technique of choice if peri-implant dehiscence and fenestration defects are suspected. The higher radiation dose and the presence of beam hardening artifacts are the main drawbacks of CBCT imaging techniques. This study aims to evaluate the influence of low-dose cone beam computed tomography (LD-CBCT) and metal artifact reduction (MAR) tool on the assessment of peri-implant dehiscence and fenestration.

METHODOLOGY

Thirty titanium implants were inserted into bovine rib blocks. Twenty had standardized bone defects (10 with dehiscence and 10 with fenestration), while the remaining 10 were used as control group with no defects. Radiographic examinations held with high-definition CBCT (HD-CBCT) and LD-CBCT with and without application of MAR tool. Images were assessed by four examiners for the presence or absence of peri-implant defects. The area under the area under the receiver operating characteristic (ROC) curve (AUC), sensitivity, specificity, and accuracy were calculated for all radiographic protocols.

RESULTS

In the absence of MAR tool, there was no difference in AUC and diagnostic values between LD-CBCT and HD-CBCT for detection of both defects. When the MAR tool was applied, the AUC values, sensitivity, and accuracy were higher in HD-CBCT than in LD-CBCT for the detection of both defects, especially for the dehiscence, while specificity remained the same.

CONCLUSION

LD-CBCT can be used in the evaluation of peri-implant dehiscence and fenestration without any decrease in diagnostic accuracy. The application of MAR tool decrease the diagnostic ability of both defects, especially for the detection of dehiscence defects.

Effect of the Field of View Size on CBCT Artifacts Caused by the Presence of Metal Objects in the Exomass

Materials and Methods

In this in vitro experimental study, titanium implants, teeth with cobalt-chromium (Co-Cr) intracanal posts, and teeth with mesio-occluso-distal (MOD) amalgam restorations were placed in an empty socket of the extracted third molar of a human mandible. These metallic materials were differently arranged in the exomass (zone outside of the FOV). A polypropylene tube containing dipotassium phosphate was placed in the empty socket of the right canine tooth in a dry human mandible. CBCT scans were taken with a NewTom VGI (Verona, Italy) scanner using a 6 × 6 cm and an 8 × 8 cm FOV. The histogram tool of OnDemand software (Cybermed, Seoul, Korea) was used to select circles with a 1.5 mm diameter as the (ROI) at the center of the homogenous solution of dipotassium phosphate tube on the axial plane. The mean gray value (GV) and its standard deviation (SD) in the region of interest (ROI) were calculated (P > 0.05). The data were analyzed by SPSS 26.

Results

The reduction in the size of the FOV significantly decreased the mean GV (P < 0.001). Metal objects in the exomass significantly decreased the mean GV (P < 0.001), and minimum mean GV and maximum SD were recorded for amalgam, followed by Co-Cr intracanal posts, and titanium implants. The unilateral presence of a metal object was associated with a higher mean GV and lower SD (P < 0.001).

Conclusion

Using a smaller FOV increases the size of the exomass, which may negatively affect the image quality. Metal objects in the exomass decrease the GV of CBCT scans and adversely affect the image quality.

Does the size of an object containing dental implant affect the expression of artifacts in cone beam computed tomography imaging?

Background

Artifacts fault image quality but handling several factors can affect it. This study was conducted to investigate the effect of object size on artifacts in cone-beam computed tomography systems.

Methods

Five phantoms, each containing a titanium implant in a sheep bone block, were fabricated of various sizes ranging from XS to XL: The M phantom was the same size as the device’s field of view (FOV). The L and XL phantoms were 20 and 40% larger than the FOV while the S and XS phantoms were 20 and 40% smaller than FOV, respectively. Ballistic gelatin was used to fill the phantoms. Phantoms were scanned by NewTom VGI and HDXWill Q-FACE. The mean and standard deviation (SD) of gray values in each 120 ROI was obtained by OnDemand software. The contrast to noise ratio (CNR) was also calculated.

Results

The gray value in S and M phantoms were more homogenous. The lowest SD value (10.20) was found in S phantom. The highest value for SD (125.16) was observed in XL phantom. The lowest (4.47) and highest (9.92) CNR were obtained in XL and S phantoms, respectively. HDXWill Q-FACE recorded a higher SD and a lower CNR than NewTom VGI (P < 0.05).

Conclusion

Object dimensions of the FOV size or up to 20% smaller provided better image quality. Since the dimensions of soft tissue in most patients are larger than the selective FOV, it is recommended that in CBCT artifacts studies, an object with dimensions closer to the patient’s dimensions be used to better relate the results with the clinical condition, because the sample dimensions affect the amount of artifacts.

The Impact of Cone-Beam Computed Tomography Exposure Parameters on Peri-Implant Artifacts: A Literature Review

Cone-beam computed tomography (CBCT) amounts to an excellent diagnostic tool to evaluate the peri-implant bone thickness in all dimensions. Despite the unquestionable advantages of CBCT, potential artifacts around dental implants might disturb the proper assessment of the surrounding structures. The artifacts may mask osseointegration, shallow bone defects, and other types of radiolucency, which make it difficult to establish an early diagnosis of bone loss. Proper diagnosis of bone defect is necessary to decide about surgical intervention. The aim of this literature review is to assess the CBCT exposure causing artifacts on the peri-implant structures. An electronic search of MEDLINE (PubMed) database includes studies published before July 2021 and supplemented by manual research. Clinical, ex vivo, in vitro, and animal studies evaluating the relationship between exposition parameters and occurrence of artifacts around the dental implant in CBCT studies were included. A literature review revealed that kilovoltage, tube current, and field of view may affect the occurrence of artifacts around dental implants, all of which would compromise radiological evaluation. Therefore, it is feasible to reduce the incidence of artifacts and improve the image quality by appropriate modification of the exposure parameters. However, the reduction of artifacts is often associated with a significant increase in radiation exposure; hence, an effort should be made to minimize the radiation dose in line with the ALARA (as low as reasonably achievable) principle.

The metal post material influences the performance of artefact reduction algorithms in CBCT images

Abstract This study aimed to assess the effect of the MAR tool on the expression of artefacts in different regions of a tooth restored with different types of metal posts. Alveolar sockets (anterior, and posterior region) of a mandible and an unirradicular tooth were used. Cone beam computed tomography scans of the tooth without a metal post, and with cobalt-chromium (Co-Cr), nickel-chromium (Ni-Cr), or silver-palladium (Ag-Pd) were individually obtained, with 2 MAR conditions: disabled, and enabled. In an axial reconstruction, lines of interest (LOIs) were set around the canal: 4 in oblique (mesiobuccal, distobuccal, mesiolingual, distolingual) directions, and 4 in orthogonal (mesial, distal, buccal, lingual) directions. Beam-hardening artefacts expression was determined by calculating the difference in the mean of gray values (DMGV) between the experimental and control groups for each LOI. There was no significant difference in the DMGV values between “without MAR” and “with MAR” for any LOI, in neither anterior nor posterior mandible (p>0.05), for the Ni-Cr and Co-Cr groups. For the Ag-Pd, significant differences in the DMGV values were observed between “without MAR” and “with MAR” for most LOIs (p<0.05), mainly in oblique directions in the anterior region, and mesio-distal direction in the posterior region. MAR acted mostly in hypodense artefacts (negative DMGV). The effectiveness of the MAR tool of the OP300 CBCT unit varied according to the post material tested. It was effective in reducing the expression of artefacts raised by the Ag-Pd post, mainly in the tooth regions affected by hypodense artefacts, regardless of the mandibular region.

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.