In vitro diagnostic accuracy of low‐dose CBCT for evaluation of peri‐implant bone lesions

Efficacy of two radiographic algorithms for detection of peri-implant bone defects on cone-beam computed tomography scans

BACKGROUND

Early detection of peri-implant bone defects can improve long-term durability of dental implants. By the advances in cone-beam computed tomography (CBCT) scanners and introduction of new algorithms, it is important to find the most efficient protocol for detection of bone defects. This study aimed to assess the efficacy of metal artifact reduction (MAR) and advanced noise reduction (ANR) algorithms for detection of peri-implant bone defects.

MATERIALS AND METHODS

In this in vitro study, 40 titanium implants were placed in 7 sheep mandibles. Crestal, apical, and Full defects (n = 10 from each type) were created around the implants, and 10 implants were also placed as controls. CBCT scans were obtained in four modes: with MAR, with ANR, with both MAR and ANR, and without any filter. Totally, 28 scans were obtained and evaluated by a radiologist and a maxillofacial surgeon. The observers recorded their observations in a checklist, and data were analyzed by SPSS version 21 using the kappa coefficient of agreement, sensitivity and specificity values, area under the receiver operating characteristic (ROC) curve (AUC), intraclass correlation coefficient, t-test and paired t-test (P < 0.05).

RESULTS

The inter-observer agreement was high for detection of all defects in all modes except with ANR. No significant difference was found in AUC and diagnostic accuracy of different scan modes (P > 0.05). The most common diagnostic error was related to misdiagnosis of control group with full defect with ANR filter, such that the existing bone was not detected. Defect depth was averagely over-estimated while defect length was under-estimated. Correct diagnosis of defects had the highest frequency when both filters were on.

CONCLUSION

The diagnostic accuracy and sensitivity for detection of different defect types were not significantly different in different scan modes but activation of ANR filter significantly decreased the specificity and positive predictive value compared with no use of filter.

Validation of 2D lateral cephalometric analysis using artificial intelligence-processed low-dose cone beam computed tomography

Objectives

Traditional cephalometric radiographs depict a three-dimensional structure in a two-dimensional plane; therefore, errors may occur during a quantitative assessment. Cone beam computed tomography, on the other hand, minimizes image distortion, allowing essential areas to be observed without overlap. Artificial intelligence can be used to enhance low-dose cone beam computed tomography images. This study aimed to clinically validate the use of artificial intelligence-processed low-dose cone beam computed tomography for generating two-dimensional lateral cephalometric radiographs by comparing these artificial intelligence-enhanced radiographs with traditional two-dimensional lateral cephalograms and those derived from standard cone beam computed tomography.

Methods

Sixteen participants who had previously undergone both cone beam computed tomography and plain radiography were selected. Group I included standard lateral cephalometric radiographs. Group II included cone beam computed tomography-produced lateral cephalometric radiographs, and Group III included artificial intelligence-processed low-dose cone beam computed tomography-produced lateral cephalometric radiographs. Lateral cephalometric radiographs of the three groups were analyzed using an artificial intelligence-based cephalometric analysis platform.

Results

A total of six angles and five lengths were measured for dentofacial diagnosis. There were no significant differences in measurements except for nasion-menton among the three groups.

Conclusions

Low-dose cone beam computed tomography could be an efficient method for cephalometric analyses in dentofacial treatment. Artificial intelligence-processed low-dose cone beam computed tomography imaging procedures have the potential in a wide range of dental applications. Further research is required to develop artificial intelligence technologies capable of producing acceptable and effective outcomes in various clinical situations.

Clinical significance

Replacing standard cephalograms with cone beam computed tomography (CBCT) to evaluate the craniofacial relationship has the potential to significantly enhance the diagnosis and treatment of selected patients. The effectiveness of low-dose (LD)-CBCT was assessed in this study. The results indicated that lateral cephalograms reconstructed using LD-CBCT were comparable to standard lateral cephalograms.

Do the number of zirconia implants and the thickness of CBCT image reconstruction affect the detection of peri-implant bone defect? A diagnostic accuracy ex vivo study

OBJECTIVES

To evaluate the influence of multiplanar reconstruction thickness on the detection of peri-implant bone defects with a standalone zirconia implant and compare it to when another implant is in the vicinity using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Five dry human mandibles were used to create twenty implant sites in the second premolar and first molar regions. The OP300 Maxio was used to acquire CBCT images (90 kVp, 6.3 mA, 5 × 5 cm FOV, and 0.125 mm3 voxel size) before and after creating 3 mm peri-implant bone defects in the buccal aspect of the premolar region. Half of the scans featured a single zirconia implant in the premolar region, while the others had two implants in the premolar and molar regions. Three reconstruction thicknesses (0.125 mm, 1 mm, and 2 mm) were considered for the multiplanar reconstruction analyses. Five oral and maxillofacial radiologists assessed the detection of peri-implant bone defects using a 5-point scale. Diagnostic parameters were calculated and compared using Two-way ANOVA (α = .05).

RESULTS

The studied factors showed no significant influence on the diagnosis of peri-implant bone defects (p > .05). Diagnostic performance was notably higher with a single implant, especially with a 2-mm reconstruction thickness (AUC = 0.88, sensitivity = 0.68, specificity = 0.94). Although the differences were not statistically significant, the results were more modest when two implants were present (AUC = 0.80, sensitivity = 0.58, specificity = 0.82).

CONCLUSIONS

The presence of an adjacent zirconia implant and variations in reconstruction thickness did not influence the detection of 3 mm buccal peri-implant bone defects on CBCT images.

Tooth segmentation by low-dose CBCT for orthodontic treatment planning : Explorative ex vivo validation

PURPOSE

Three-dimensional imaging has become an increasingly important component of orthodontics. Associated with this, however, is a higher radiation exposure for patients. New cone-beam computed tomography (CBCT) devices have been developed that can provide low-dose CBCT (LD-CBCT). We hypothesized that LD-CBCT is as precise and reproducible as standard high-dose CBCT (HD-CBCT) in segmenting roots and crowns as well as measuring tooth length.

METHODS

HD-CBCT and LD-CBCT scans were taken of four human cadaveric heads. Thirty single-rooted teeth were segmented twice by one investigator. The length of each tooth was also measured. Lin's concordance correlation coefficient (CCC) was calculated to assess the agreement of HD-CBCT and LD-CBCT measurements and the intraclass correlation coefficient (ICC) was calculated to assess intrarater reliability. Analyses were supported by Bland-Altman plots.

RESULTS

Volume measurements obtained using HD-CBCT were significantly higher than those obtained using LD-CBCT (p < 0.001). CCC was 0.975 (95% confidence interval [CI] = 0.956-0.986) indicating excellent agreement between the two modalities. Intrarater reliability between the two sets of LD-CBCT and HD-CBCT volume measurements was excellent (ICC = 0.998, 95%CI = 0.995-0.999 [HD-CBCT], ICC = 0.997, 95%CI = 0.992-0.998 [LD-CBCT]). CCC for tooth length measurements was 0.991 (95% CI = 0.983-0.995), indicating excellent agreement between HD-CBCT and LD-CBCT. Intrarater reliabilities between the two sets of tooth length measurements were also excellent for both methods (ICC = 0.998, 95%CI = 0.995-0.999 [HD-CBCT], ICC = 0.997, 95%CI = 0.992-0.998 [LD-CBCT]).

CONCLUSIONS

Within the limitations of this experimental setting, LD-CBCT is as valid as HD-CBCT for measuring tooth length. Regarding the volume differences, in vivo studies are required to determine their clinical relevance.

Low-dose CBCT protocols in implant dentistry: a systematic review

OBJECTIVE

To evaluate the state-of-the-art evidence for applying low-dose CBCT protocols in 3 stages of implant therapy (planning, insertion, and follow-up examination of peri-implantitis) and assess the overall body of evidence presented in the literature.

STUDY DESIGN

The search was conducted in the MEDLINE/Pubmed and Scopus databases. Studies comparing low-dose CBCT protocols to a relevant reference standard in relation to any stage of implant therapy were included. Data extraction and quality assessment were performed for all included studies.

RESULTS

Sixteen studies were included. Low-dose protocols were reported to result from reduction of the exposure parameters of kV, mA, resolution (through increased voxel size), exposure time, and scanning trajectory. The current literature suggests that low-dose CBCT protocols perform similarly in the 3 stages of implant therapy compared to higher resolution protocols regarding objective measurements, with adverse impacts mostly on subjective assessment of image quality. The results also suggest that CBCT-based bone measurements are similar to direct measurements, independent of the imaging protocol. Reduction in all parameters except kV seems feasible as the basis of low-dose CBCT protocols for implant therapy.

CONCLUSIONS

The use of low-dose CBCT protocols does not impact objective image quality assessment in any stage of implant therapy. Clinical studies are needed to indicate if the reported results can be extrapolated to improve patient care in relation to the responsible use of ionizing radiation.

Evaluation of the accuracy of cone beam computed tomography (CBCT) in the detection of peri-implant fenestration

BACKGROUND

Accurate assessment of the bone supporting the implant is crucial. Early detection of bone defects around the implant can prevent the loss of bone support that ultimately leads to the loss of the implant. Therefore, the purpose of this study is to check the accuracy of CBCT in detecting peri-implant fenestrations around the implant.

MATERIALS & METHODS

In this laboratory study, healthy beef ribs were used. The ribs were divided into three groups of 12 (control group, 1-2 mm fenestration group, and 2-3 mm fenestration group). The blocks were cut to a length of 20 mm and 36 osteotomies with dimensions of 4 × 12 mm were made by the periodontist in order to place the implant in these bone blocks. Then the titanium implant was placed in the holes and the initial scan was performed with CBCT. In the second group, fenestration-like lesions were created on the same buccal side at a distance of 10 mm from the crest with a diameter of 1-2 mm and in the third group with a diameter of 2-3 mm, and the CBCT scan was performed again with the same parameters. Two radiologists evaluated the images twice for the presence and absence of fenestration.

RESULTS

There was no statistically significant difference between direct measurements and CBCT in the fenestration group of 1-2 mm (p < 0.05), but there was a significant difference between direct measurements and CBCT in the fenestration group of 2-3 mm and underestimation was observed in CBCT measurements.

CONCLUSION

The findings of this study showed that CBCT radiography has a higher accuracy in measuring the fenestration around the implant with a smaller diameter and has an acceptable diagnostic value in detecting bone loss around the implant.

Influence of Examiner Experience on the Measurement of Bone-Loss by Low-Dose Cone-Beam Computed Tomography: An Ex Vivo Study

The aim of this study was to investigate the influence of examiner experience on measurements of bone-loss using high-dose (HD) and low-dose (LD) CBCT. Three diagnosticians with varying levels of CBCT interpretation experience measured bone-loss from CBCT scans of three cadaveric heads at 30 sites, conducting measurements twice. Between the first and second measurements, diagnostician 2 and diagnostician 3 received training in LD-CBCT diagnostics. The diagnosticians also classified the certainty of their measurements using a three-grade scale. The accuracy of bone-loss measurements was assessed using the absolute difference between observed and clinical measurements and compared among diagnosticians with different experience levels for both HD and LD-CBCT. At baseline, there was a significant difference in measurement accuracy between diagnostician 1 and diagnostician 2, and between diagnostician 1 and diagnostician 3, but not between diagnostician 2 and diagnostician 3. Training improved the accuracy of both HD-CBCT and LD-CBCT measurements in diagnostician 2, and of LD-CBCT measurements in diagnostician 3. Regarding measurement certainty, there was a significant difference among diagnosticians before training. Training enhanced the certainty for diagnosticians 2 and 3, with a significant improvement noted only for diagnostician 3. Examiner experience level significantly impacts the accuracy and certainty of bone-loss measurements using HD- and LD-CBCT.

Impact of acquisition volume on cone beam computed tomography imaging of marginal bone: an ex vivo study

OBJECTIVE

The current study explores whether there is a clinically relevant distinction in the measurement of marginal bone loss when comparing high-dose (HD) versus low-dose (LD) cone beam computed tomography (CBCT) protocols in small and large acquisition volumes.  Material and Methods: CBCTs of four human cadaveric preparates were taken in HD and LD mode in two different fields of view 8 × 8 cm2 (LV) and 5 × 5 cm2 (SV). In total, 43 sites of 15 teeth were randomly chosen, and marginal bone loss was measured twice in all protocols at 43 sites of 15 teeth by one calibrated investigator. Bland-Altman plots and Lin's concordance correlation coefficient (CCC) were calculated to assess the extent of agreement of the measurements. Additionally, the rater scored the certainty in each of the measurements.

RESULTS

For HD-CBCT CCC of measurements obtained using SV versus LV was 0.991. CCC of measurements obtained using SV versus LV of LD-CBCT was 0.963. Both CCC values indicated excellent agreement between the two volumes in both protocols.  CCC also indicated high intramodality correlation between HD-CBCT and LD-CBCT independent of the acquisition volume (0.963 - 0.992). Bland-Altman plots also indicated no substantial differences. Results of certainty scoring showed significant differences (p = 0.004 (LV), p < 0.001(SV)) between the LD and HD-CBCT.

CONCLUSIONS

Accuracy of measurements of bone loss shows no clinical noticeable effects depending on the CBCT volume in this ex vivo study. There appears to be no relevant advantage of SV over LV, neither in HD-CBCT nor in LD-CBCT and additionally no relevant advantage of HD versus LD in visualizing marginal bone loss.

Analysis of peri-implant bone defects by using cone beam computed tomography (CBCT): an integrative review

The objective of this work was to perform an integrative review of the inspection of peri-implant bone defects using cone beam computed tomography (CBCT). An electronic search was performed in the PubMed database using the following scientific terms: CBCT or Cone Beam computed tomography; dental implant; peri-implant; bone loss; defects. The survey identified 267 studies, of which 18 were considered relevant to this study. These studies provided important data taking into account the accuracy of cone beam computed tomography in the detection and measurement of peri-implant bone defects such as fenestrations, dehiscence and intraosseous circumferential defects. The effectiveness of CBCT in aiding in geometric bone calculations and in the diagnosis of peri-implant defects was influenced by factors such as artefacts, defect size, bone wall thickness, implant material, adjustment of acquisition parameters and observer experience. A not insignificant number of studies compared intraoral radiography to CBCT in the detection of peri-implant bone loss. CBCT was clearly superior to intraoral radiography in the detection of all peri-implant bone defects, except for defects located in the interproximal zone. In general, studies have shown that peri-implant bone measurements adjacent to the implant surface can be correctly determined, as well as the diagnosis of peri-implant bone defects with an average discrepancy of less than 1 mm from the actual measurement of the defect.

Reliability and accuracy of intraoral radiography, cone beam CT, and dental MRI for evaluation of peri-implant bone lesions at zirconia implants - an ex vivo feasibility study

OBJECTIVES

To determine the reliability and accuracy of intraoral radiography (IR), cone-beam-computed tomography (CBCT), and dental magnetic resonance imaging (dMRI) in measuring peri‑implant bone defects around single zirconia implants.

METHODS

Twenty-four zirconia implants were inserted in bovine ribs with various peri‑implant defect sizes and morphologies. True defect extent was measured without implant in CBCT. Defects were measured twice in IR, CBCT, and dMRI with the inserted implant by three experienced readers. Reliability was assessed by ICC, accuracy by the Friedman test, and post-hoc-Tukey's test.

RESULTS

A comparable good to excellent intra- and inter-reader reliability was observed for all modalities (intra-/inter-rater-CC range for IR; CBCT; dMRI: 0.81-0.91/0.79;0.87-0.97/0.96;0.87-0.95/0.94). Accuracy was generally high, with mean errors below 1 mm in all directions. However, measuring defect depth in the mesiodistal direction was significantly more accurate in dMRI (0.65 ± 0.38 mm) compared to IR (2.71 ± 1.91 mm), and CBCT (1.98 ± 1.97 mm), p-values ≤ 0.0001 respectively ≤ 0.01.

CONCLUSIONS

Osseous defects around zirconia implants can be reliably measured in IR/CBCT/dMRI in the mesiodistal directions. In addition, CBCT and dMRI allow assessment of the buccolingual directions. dMRI provides a comparable accuracy in all directions, except for the mesiodistal defect depth, where it outperforms IR and CBCT.

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.

Influence of Exposure Parameters and Implant Position in Peri-Implant Bone Assessment in CBCT Images: An In Vitro Study

The aim of this study was to assess the impact of dimensional distortion and its changes with modification of exposure setting parameters on the measurements of peri-implant bone margin. Ten titanium dental implants (InKone Primo, Global D, Paris, France) were placed in two prepared bovine ribs. Two bone models and an implant-with-transfer model were scanned with 3shape E4 (3shape, Copenhagen, Denmark) laboratory scanner. Cone beam computed tomography (CBCT) images of two bone models were taken with different values of voltage (60, 70, 80, 90 kV), tube current (4, 10 mA) and voxel size (200, 300 µm). All the data were superimposed using planning software, and the measurements of buccal bone thickness in two selected regions were performed both using CBCT and scan cross-sections. The mean squared error (MSE) being the squared differences between measurements was used in the accuracy assessment of the CBCT device. A one-way ANOVA revealed significant differences between voltage and MSE (p = 0.044), as well as implant position and MSE (p = 0.005). The distortions of measurements depend on bone margin thickness, and the higher the distance to measure, the higher the error. Accurate measurements of buccal bone thickness (MSE below 0.25) were achieved with voltage values of 70, 80, and 90 kV.

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.

Diagnostic accuracy of imaging examinations for peri-implant bone defects around titanium and zirconium dioxide implants: A systematic review and meta-analysis

Purpose

This systematic review and meta-analysis assessed the diagnostic accuracy of imaging examinations for the detection of peri-implant bone defects and compared the diagnostic accuracy between titanium (Ti) and zirconium dioxide (ZrO₂) implants.

Materials and Methods

Six online databases were searched, and studies were selected based on eligibility criteria. The studies included in the systematic review underwent bias and applicability assessment using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool and a random-effect meta-analysis. Summary receiver operating characteristic (sROC) curves were constructed to compare the effect of methodological differences in relation to the variables of each group.

Results

The search strategy yielded 719 articles. Titles and abstracts were read and 61 studies were selected for full-text reading. Among them, 24 studies were included in this systematic review. Most included studies had a low risk of bias (QUADAS-2). Cone-beam computed tomography (CBCT) presented sufficient data for quantitative analysis in ZrO₂ and Ti implants. The meta-analysis revealed high levels of inconsistency in the latter group. Regarding sROC curves, the area under the curve (AUC) was larger for the overall Ti group (AUC=0.79) than for the overall ZrO₂ group (AUC=0.69), but without a statistically significant difference between them. In Ti implants, the AUCs for dehiscence defects (0.73) and fenestration defects (0.87) showed a statistically significant difference.

Conclusion

The diagnostic accuracy of CBCT imaging in the assessment of peri-implant bone defects was similar between Ti and ZrO₂ implants, and fenestration was more accurately diagnosed than dehiscence in Ti implants.

Ex-vivo imaging of buccal and oral periodontal bone with low-dose CBCT in porcine jaws

OBJECTIVES

New CBCT devices have been developed which can provide "low-dose CBCTs (LD-CBCT)". Aim of this study is to investigate the suitability of LD-CBCT for measurement of alveolar buccal/oral bone.

METHODS AND MATERIALS

Vestibular and oral bone loss of the teeth of seven porcine mandibles free of soft tissues were investigated by Micro-CT and three CBCT-modes: high-dose (HD), standard-dose (SD) and low-dose (LD). Radiographic measurements of bone loss (bl) and vestibular and oral bone thickness (bt) were made by two raters at 69 sites. Measurement means and differences, Intraclass correlation (ICC) and Bland-Altman plots were calculated.

RESULTS

ICCs between raters(r) concerning bl were 0.954 for HD, 0.949 for SD and 0.945 for LD; concerning bt they were 0.872 for HD, 0.845 for SD and 0.783 for LD. Means of differences of bt measurements were -0.01 mm(r1)/0.00 mm(r2) for HD, 0.04 mm(r1)/0.02 mm(r2) for SD and 0.02 mm(r1)/0.04 mm(r2) for LD; for bl measurements they were 0.06 mm(r1)/0.05 mm(r2) for HD, -0.01 mm(r1)/0.13 mm(r2) for SD and 0.07 mm(r1)/0.16 mm(r2) for LD.Linear regression indicates no noticeable differences between methods and the raters with respect to bl and bt.

CONCLUSIONS

Relating to the CBCT-device used in this study, LD-CBCT is a promising method to detect and describe buccal and oral periodontal bl and bt. Further studies with human anatomic structures must confirm these results.

Measuring peri-implant bone lesions using low-dose cone-beam computed tomography

PURPOSE

High-definition cone-beam computed tomography (HD-CBCT) offers superior image quality at the cost of higher radiation dose compared to low-dose CBCT (LD-CBCT). The aim of this study was to investigate whether peri-implant bone lesions can be accurately quantified using LD-CBCT, even when including the influence of surrounding tissues.

METHODS

Twelve titanium implants restored with all-ceramic crowns were placed in bovine bone, and peri-implant lesions were prepared. Radiographic imaging was performed using IR (intraoral radiography), HD-CBCT and LD-CBCT. To simulate the in-vivo situation, the samples were placed inside a dry human mandible, and a second LD-CBCT imaging was performed (LD-CBCT*). The datasets were presented to four observers in random order. Maximum lesion depth and width were measured in a standardized mesiodistal slice in IR, HD-CBCT, LD-CBCT, and LD-CBCT*. Mean lesion depth and width measurements for each sample in HD-CBCT served as reference.

RESULTS

Interrater agreement was slight for depth and excellent for width in HD-CBCT and both LD modes. For all observers, measurement deviations from HD-CBCT were below 0.3 mm in the LD protocols (LD-CBCT depth: 0.22 ± 0.17 mm, width: 0.22 ± 0.13 mm; LD-CBCT* depth: 0.24 ± 0.23 mm, width: 0.25 ± 0.21 mm) and at 0.4 mm in IR.

CONCLUSIONS

Absolute differences between LD-CBCT and HD-CBCT are small, although surrounding tissues decrease LD-CBCT image quality. Within the limitations of an in-vitro trial, LD-CBCT may become an adequate imaging modality for monitoring peri-implant lesions at a substantially decreased radiation dose.

Predictability and image quality of low-dose cone-beam computed tomography in computer-guided implantology: An experimental study

OBJECTIVES

To investigate the predictability and image quality of low-dose cone-beam computed tomography (LD-CBCT) in computer-guided implantology.

METHODS

Pig cadaver mandibles were imaged using high-definition CBCT (HD-CBCT) and LD-CBCT (HD-CBCT: 85 kV, 6 mA, 14.2 s, 767 frames, 1184 mGycm², voxel size 80 µm, effective dose 231 µSv; LD-CBCT: 85 kV, 10 mA, 2.1 s, 384 frames, 84 mGycm², voxel size 160 µm, effective dose 16 µSv; Orthophos SL, Dentsply Sirona, Bensheim, Germany). Digital impressions were taken using intraoral scanning (IOS; Omnicam, Dentsply Sirona). Data of CBCT modalities and IOS were aligned. Forty-eight implants were planned virtually (24 implants per modality; Bone Level 4.1 × 10 mm; Straumann AG, Basel, Switzerland). Implants were inserted using templates by initial pilot drilling ("partially-guided implantation"). Implant positions were recorded using IOS. Geometric deviations between planned and definitive positions were assessed regarding implant apex, entry-point and angle. CBCT image quality was evaluated by raters twice on a four point scale. The results were exploratively compared (linear models, Mann-Whitney-U tests).

RESULTS

Regarding implant apex, deviations were greater for LD-CBCT (mean 3.0±1.2 mm), as compared to HD-CBCT (mean 2.3±1.1 mm). For entry-point, no distinct difference was detected with a mean deviation of 1.4±0.9 mm in LD-CBCT, and 1.7±0.6 mm in HD-CBCT. Regarding angle, deviations were greater for LD-CBCT (mean 13.2±6.3°), as compared to HD-CBCT (mean 9.2±5.3°). The image quality of HD-CBCT provided to be better (mean 2.7±0.6) than that of LD-CBCT (mean 2.5±0.6).

CONCLUSIONS

Within the partially-guided approach, the results underline the potential of LD-CBCT alternatively to HD-CBCT for computer-guided implantology. Advantages of HD-CBCT need to be balanced against the higher radiation dose.

Influence of metal artefact reduction tool on the detection of vertical root fractures involving teeth with intracanal materials in cone beam computed tomography images: A systematic review and meta-analysis

BACKGROUND

The effectiveness of the metal artefact reduction (MAR) tool for the detection of vertical root fracture (VRF) by cone beam computed tomography (CBCT) images is controversial.

OBJECTIVE

To evaluate the effectiveness of the MAR tool on VRF detection involving teeth with intracanal materials in CBCT images.

METHODOLOGY

In September 2019, an electronic search was performed in six databases (PubMed, Scopus, Web of Science, Cochrane, Lilacs and Embase). The electronic search was updated in May 2020 through searches in Google Scholar and references of included studies (embracing the electronic and gray literature searches). No language or year restrictions were applied. Independently, two reviewers examined titles, abstracts and full texts according to the eligibility criteria that were as follows: diagnostic studies that evaluated the effectiveness of the MAR tool on the diagnosis of VRF in human teeth (laboratory or in vivo studies) on CBCT images. The risk of bias was evaluated using the Quality Assessment Tool for Diagnostic of Accuracy Studies-2 (QUADAS-2). For conducting the meta-analysis, the values of sensitivity, specificity, diagnostic odds ratio (DOR) and area under the ROC curve (AUC) were obtained, considering the subgroups with and without MAR active. The Grading of Recommendation, Assessment, Development and Evaluation instrument was applied to assess the level of evidence across the studies using GRADEpro software.

RESULTS

A total of 8 laboratory studies were included in both systematic review and meta-analysis. The values of sensitivity, specificity, DOR and AUC to VRF diagnosis with and without MAR active were, respectively, 0.586 and 0.603; 0.699 and 0.713, 3.037 and 3.767; 0.67 and 0.71. The quality of the evidence suggested low confidence in estimating the outcomes.

DISCUSSION

The MAR tool decreased slightly the diagnostic values of VRF involving teeth with intracanal materials in laboratory studies. However, it is important to highlight that most studies had an uncertain risk of bias.

CONCLUSIONS

Although a low level of evidence and high heterogeneity were observed in the included studies, the meta-analysis revealed better diagnosis values for VRF detection when the MAR was deactivated when analysing extracted teeth in a laboratory setting.

REGISTRATION

PROSPERO-CRD42020145222.

FUNDING

This study was financed in party by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-Brasil (CAPES).

Peri-Implant Bone Loss Measurement Using a Region-Based Convolutional Neural Network on Dental Periapical Radiographs

Determining the peri-implant marginal bone level on radiographs is challenging because the boundaries of the bones around implants are often unclear or the heights of the buccal and lingual bone levels are different. Therefore, a deep convolutional neural network (CNN) was evaluated for detecting the marginal bone level, top, and apex of implants on dental periapical radiographs. An automated assistant system was proposed for calculating the bone loss percentage and classifying the bone resorption severity. A modified region-based CNN (R-CNN) was trained using transfer learning based on Microsoft Common Objects in Context dataset. Overall, 708 periapical radiographic images were divided into training (n = 508), validation (n = 100), and test (n = 100) datasets. The training dataset was randomly enriched by data augmentation. For evaluation, average precision, average recall, and mean object keypoint similarity (OKS) were calculated, and the mean OKS values of the model and a dental clinician were compared. Using detected keypoints, radiographic bone loss was measured and classified. No statistically significant difference was found between the modified R-CNN model and dental clinician for detecting landmarks around dental implants. The modified R-CNN model can be utilized to measure the radiographic peri-implant bone loss ratio to assess the severity of peri-implantitis.

Intra- and inter-observer agreements in detecting peri-implant bone defects between periapical radiography and cone beam computed tomography: A clinical study

Background/purpose

Information regarding agreements between periapical radiograph (PA) and cone beam computed tomography (CBCT) in detecting peri-implant defect is still scarce. The aim of this clinical study was to compare agreements between PA and CBCT in detecting peri-implant bone defect.

Materials and methods

This retrospective clinical study enrolled 32 patients with both PA and CBCT filmed right after implant placement. Four modalities were used for film reading: PA1 (original), PA2 (enhanced brightness/contrast), CBCT1 (selected axial and mesial-distal direction images) and CBCT2 (all data with software). 2 experienced and 2 inexperienced observers scored all films. Intra- and inter-observer agreements were estimated with Cohen's kappa coefficient. Categorized agreements were compared and differences among four modalities were calculated.

Results

Agreements of PA were better than CBCT when detecting peri-implant bone defects in inter-observer agreements (median kappa 0.471 vs. 0.192; p = 0.016). Moreover, agreements in experienced observers were better than inexperienced observers (median kappa 0.883 vs. 0.567; p < 0.001). There was significant difference among four modalities except for experienced observer 2 (p = 0.218).

Conclusion

Agreements of PA are better than CBCT when detecting peri-implant bone defects, especially for inter-observer agreements. Experienced observers are more consistent in assessment than inexperienced ones.

Diagnostic accuracy of 870-nm spectral-domain OCT with enhanced depth imaging for the detection of caries beneath ceramics

OBJECTIVES

To evaluate the diagnostic accuracy of optical coherence tomography (OCT) for the non-invasive detection of caries adjacent to ceramic materials.

METHODS

Disks made from five ceramic materials (hybrid ceramic, feldspathic ceramic, zirconia-reinforced lithium silicate, lithium disilicate, and high-translucent zirconia) were ground to the recommended material thickness for single crown restorations and laminated with a 100 μm thick layer of one of three adhesive cements. The disks were fixed to extracted human molars with or without carious lesions of one of three standardized sizes. A total of 240 stacks of cross-sectional scans obtained using an 870-nm SD-OCT with enhanced depth imaging (EDI) were presented to five raters. Diagnostic accuracy was determined by rating the teeth beneath the cemented material as carious or healthy.

RESULTS

Carious samples were distinguished from sound teeth with high diagnostic accuracy, even for early stage caries. Sensitivity (SE) and specificity (SP) pooled over all raters and all materials were 0.9 and 0.97, respectively. When analyzing the effect of the ceramic and cement materials on detection rates, high SE and SP values of >0.96 and >0.91, respectively, were recorded for lithium disilicate, zirconia-reinforced lithium silicate, and high-translucent zirconia irrespective of the cement type. For hybrid and feldspathic ceramics, the cement material was found to have a significant effect on caries detection.

CONCLUSIONS

Given its high diagnostic accuracy, 870-nm SD-OCT with EDI might be useful for the detection of caries beneath restorative materials. The effect of the prescribed ceramic and cement material on optical penetration depth is substantial.

Developing evidence-based clinical imaging guidelines of justification for radiographic examination after dental implant installation

BACKGROUND

This study aimed to develop evidence-based clinical imaging guidelines to assess the proper implant location following implant surgery and identify potential complications during follow-up.

METHODS

The guideline development process employed an adaptation methodology in accordance with the Korean clinical imaging guidelines (K-CIG). Core (Ovid-Medline, Ovid-Embase, National Guideline Clearinghouse, and Guideline International Network) and domestic databases (KoreaMed, KMbase, and KoMGI) were searched used to retrieve guidelines, and two reviewers analyzed the retrieved articles. The articles were included in this review using well-established inclusion criteria.

RESULTS

Our online search identified 66 articles, of which 3 were selected for the development of the guidelines. Consequently, based on these three guidelines, we formulated distinct recommendations regarding the appropriate imaging modalities that should be used following implant placement.

CONCLUSIONS

Conventional imaging (e.g., periapical or panoramic radiography) should be the first choice for assessing the implant following its placement and osseointegration. The metal artifacts in Cone Beam Computed Tomography (CBCT) should be considered. However, CBCT is recommended for patients with sensory abnormalities following dental implant surgery to evaluate and identify the underlying cause of implant complications and to determine the appropriate treatment.

Cone beam computed tomography artefacts around dental implants with different materials influencing the detection of peri-implant bone defects

OBJECTIVES

To investigate the diagnostic accuracy of cone beam computed tomography (CBCT) for the diagnosis of peri-implant bone defects of titanium (Ti), zirconium dioxide (ZrO₂ ) or titanium-zirconium (Ti-Zr) alloy implants.

MATERIALS AND METHODS

Ti, Ti-Zr or ZrO₂ implants with two diameters (3.3 mm, 4.1 mm) and one length (10 mm) were inserted in the angle of the mandible of six fresh defrosted pig jaws. Out of the 12 implants inserted, 6 served in the test group with standardized buccal peri-implant bone defects, whereas 6 served as control without bone defects. CBCTs were performed with three acquisition protocols (standard, high and low dose) using two devices. Four observers analysed CBCTs as follows: (a) presence of a peri-implant defect; (b) presence of peri-implant artefacts and impact on defect diagnosis; and (c) linear measurements of buccal peri-implant defect including height and width (in mm).

RESULTS

CBCT device, CBCT settings, implant material, implant diameter and observer background did not significantly influence diagnostic accuracy. The sensitivity and specificity values were high for defect detection. ZrO₂ led to a lower than average diagnostic accuracy (0.781). The linear measurements of peri-implant defect were underestimated by <1 mm on average. The subjective impact of artefacts on defect diagnosis was significantly affected by implant material and observer background.

CONCLUSIONS

CBCT showed high diagnostic accuracy for peri-implant bone defect detection regardless of the device, imaging setting or implant material used. If CBCT is indicated to assess peri-implant bone disease, low dose protocols could be a promising imaging modality.

[Research advances in the use of digital surgical guides in implantology]

Dental implants have become the main choice for patients to fill in their missing teeth. A precise placement is the basis for a functional and aesthetic restoration. A digital surgical guide is a carrier that transfers the preoperative plan of dental implants to the actual surgery. This paper provides some references that can help clinicians improve the accuracy of implant surgery by stating the development, classification, advantages and disadvantages, and factors that affect the accuracy of digital guides.