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

Multi-omics insights into bone tissue injury and healing: bridging orthopedic trauma and regenerative medicine

To preserve functionality, bone is an active tissue that can constantly reconstruct itself through modeling and remodeling. It plays critical roles in the body, including maintaining mineral homeostasis, serving as the adult human body's core site of hematopoiesis, and supporting the structures of the body's soft tissues. It possesses the natural regeneration capacity, but large and complex lesions often require surgical intervention. Multiple omics integrate proteomics, metabolomics, genomics, and transcriptomics to provide a comprehensive understanding of biological processes like bone tissue injury and healing in bone tissue regeneration and engineering. Recently, bone tissue engineering and regenerative medicines have offered promising tools for bone regeneration using a multi-omics approach. Thus, this article will highlight the role of multiple omics in understanding bone tissue injury and healing. It will discuss the role of bone tissue engineering in developing bone substitutes that can replace translational medicine. Lastly, new developments in bone tissue engineering and regenerative medicine, along with multi-omics approaches, offer promising tools for bone regeneration.

Bone quality assessment around dental implants in cone-beam CT images: effect of rotation mode and metal artefact reduction tool

OBJECTIVES

The purpose of this study was to evaluate how artefacts caused by titanium and zirconia dental implants affect the bone quality assessment in CBCT images. The effect of scan mode and the use of metal artefact reduction (MAR) algorithm on artefacts suppression were taken in consideration.

METHODS

Titanium and zirconia dental implants were installed in porcine bone samples and scanned with two CBCT devices with adjustments on scan mode and with the use of MAR. The control group consisted of bone sample without implant and scanned with full-rotation scan mode without MAR. Artefacts extension and bone quality around implants were measured by deviation of grey values and bone histomorphometry measurements (trabecular volume fraction, bone specific surface, trabecular thickness, and trabecular separation), respectively. Mean difference among groups was assessed by within ANOVA with Bonferroni correction. Correlation between bone quality measurements acquired in the experimental and control groups was assessed by Spearman correlation test (α = .05).

RESULTS

No statistical difference was found for artefacts extension in images acquired by half and full-rotation modes (P = .82). The application of MAR reduced artefacts caused by titanium and zirconia dental implants, showing no statistically significant difference from the control group (titanium: P = .20; zirconia: P = .31). However, there was no correlation between bone quality measurements (P < .05).

CONCLUSIONS

Bone quality assessment was affected by the presence of artefacts caused by dental implants. Rotation mode did not affect the appearance of artefacts and bone qualitative measurements. MAR was able to decrease artefacts, however, it did not improve the accuracy of bone quality measurements.

Evaluation of Exomass-Related Artefacts Caused by Dental Implants of Different Materials in Cone-Beam Computed Tomography Scans: An Ex Vivo Study

OBJECTIVES

To evaluate the influence of different dental implant materials within the exomass on the image quality in cone-beam computed tomography (CBCT).

MATERIAL AND METHODS

Five pig jaws were scanned using four CBCT devices, first without any dental implants, followed by scans with three dental implants of the same material-pure titanium, titanium-zirconium alloy, and zirconium dioxide. Two fields of view (FOVs) were used for each device to position the implants in the exomass of a small FOV and within a large FOV. Voxel values were obtained from tubes containing a radiopaque solution to calculate mean voxel value (MVV), voxel value inhomogeneity (VVI), and image noise (IN), which were compared across implant materials and FOVs using repeated measures analysis of variance (α = 0.05). Three observers independently scored image quality using a 5-point scale.

RESULTS

In general, MVV remained unaffected, except for a significant increase in the X800 device when titanium or titanium-zirconium alloy implants were in the exomass of a small FOV (p ≤ 0.05). A trend of increased VVI was observed when implants were in the exomass of a small FOV, with a greater effect for zirconium dioxide, followed by titanium-zirconium alloy and titanium. IN was higher when implants were in the exomass, especially for zirconium dioxide implants (p ≤ 0.05). Image quality perception was consistent overall, though zirconium dioxide implants in both FOVs resulted in diminished quality.

CONCLUSIONS

The presence of implants in the exomass can negatively affect CBCT image quality, with zirconium dioxide having the greatest impact.

Development and evaluation of a deep learning model to reduce exomass-related metal artefacts in cone-beam CT: an ex vivo study using porcine mandibles

OBJECTIVES

To develop and evaluate a deep learning (DL) model to reduce metal artefacts originating from the exomass in cone-beam CT (CBCT) of the jaws.

METHODS

Five porcine mandibles, each featuring six tubes filled with a radiopaque solution, were scanned using four CBCT units before and after the incremental insertion of up to three titanium, titanium-zirconium, and zirconia dental implants in the exomass of a small field of view. A conditional denoising diffusion probabilistic model, using DL techniques, was employed to correct axial images from exomass-related metal artefacts across the CBCT units and implant scenarios. Three examiners independently scored the image quality of all datasets, including those without an implant (ground truth), with implants in the exomass (original), and DL-generated ones. Quantitative analysis compared contrast-to-noise ratio (CNR) to validate artefact reduction using repeated measures analysis of variance in a factorial design followed by Tukey test (α = .05).

RESULTS

The visualisation of the hard tissues and overall image quality was reduced in the original and increased in the DL-generated images. The score variation observed in the original images was not observed in the DL-generated images, which generally scored higher than the original images. DL-generated images revealed significantly greater CNR than both the ground truth and their corresponding original images, regardless of the material and quantity of dental implants and the CBCT unit (P < .05). Original images revealed significantly lower CNR than the ground truth (P < .05).

CONCLUSIONS

The developed DL model using porcine mandibles demonstrated promising performance in correcting exomass-related metal artefacts in CBCT, serving as a proof-of-principle for future applications of this approach.

Automated Segmentation of Graft Material in 1-Stage Sinus Lift Based on Artificial Intelligence: A Retrospective Study

OBJECTIVES

Accurate assessment of postoperative bone graft material changes after the 1-stage sinus lift is crucial for evaluating long-term implant survival. However, traditional manual labeling and segmentation of cone-beam computed tomography (CBCT) images are often inaccurate and inefficient. This study aims to utilize artificial intelligence for automated segmentation of graft material in 1-stage sinus lift procedures to enhance accuracy and efficiency.

MATERIALS AND METHODS

Swin-UPerNet along with mainstream medical segmentation models, such as FCN, U-Net, DeepLabV3, SegFormer, and UPerNet, were trained using a dataset of 120 CBCT scans. The models were tested on 30 CBCT scans to evaluate model performance based on metrics including the 95% Hausdorff distance, Intersection over Union (IoU), and Dice similarity coefficient. Additionally, processing times were also compared between automated segmentation and manual methods.

RESULTS

Swin-UPerNet outperformed other models in accuracy, achieving an accuracy rate of 0.84 and mean precision and IoU values of 0.8574 and 0.7373, respectively (p < 0.05). The time required for uploading and visualizing segmentation results with Swin-UPerNet significantly decreased to 19.28 s from the average manual segmentation times of 1390 s (p < 0.001).

CONCLUSIONS

Swin-UPerNet exhibited high accuracy and efficiency in identifying and segmenting the three-dimensional volume of bone graft material, indicating significant potential for evaluating the stability of bone graft material.

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.

The effect of a blooming artifact reduction filter on the dimensional analysis of implants

OBJECTIVE

To assess the effect of a blooming artifact reduction (BAR) filter on cone beam computed tomography (CBCT) images in the dimensional analysis of dental implants.

STUDY DESIGN

Six types of implants (n = 5 for each type) composed of titanium (3 types), titanium-zirconia alloy, zirconium oxide, and titanium-aluminum-vanadium alloy, and made with 2 manufacturing processes (milled and printed) were individually installed in a bovine rib block according to the manufacturer's protocol. CBCT images were acquired with i-CAT and Carestream scanners, randomized, and analyzed without and with the e-Vol DX BAR filter (60 images for each scanner). Implant length, diameter, and thread-to-thread distance were measured by two radiologists, with a stereomicroscopic image of each implant as the reference standard for calculation of distortion in measurements. Repeated measures ANOVA with Bonferroni corrections and intraclass correlation coefficients (ICC) were applied (α = 0.05).

RESULTS

The BAR filter significantly reduced distortion in various parameters for specific implants, aligning closely with stereomicroscopic measurements. Titanium and printed implants showed reduced dimensional distortion regardless of BAR filter use. Carestream measurements presented smaller dimensional differences than i-CAT for most implants and parameters, especially without BAR (P < .05). Interexaminer reliability was good to excellent, with ICC ranging from 0.80 to 0.95.

CONCLUSIONS

The BAR filter can enhance implant dimensional analysis, although variations based on implant material and manufacturing process were observed.

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.

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.

The current role and future potential of digital diagnostic imaging in implant dentistry: A scoping review

OBJECTIVES

Diagnostic imaging is crucial for implant dentistry. This review provides an up-to-date perspective on the application of digital diagnostic imaging in implant dentistry.

METHODS

Electronic searches were conducted in PubMed focusing on the question 'when (and why) do we need diagnostic imaging in implant dentistry?' The search results were summarised to identify different applications of digital diagnostic imaging in implant dentistry.

RESULTS

The most used imaging modalities in implant dentistry include intraoral periapical radiographs, panoramic views and cone beam computed tomography (CBCT). These are dependent on acquisition standardisation to optimise image quality. Particularly for CBCT, other technical parameters (i.e., tube current, tube voltage, field-of-view, voxel size) are relevant minimising the occurrence of artefacts. There is a growing interest in digital workflows, integrating diagnostic imaging and automation. Artificial intelligence (AI) has been incorporated into these workflows and is expected to play a significant role in the future of implant dentistry. Preliminary evidence supports the use of ionising-radiation-free imaging modalities (e.g., MRI and ultrasound) that can add value in terms of soft tissue visualisation.

CONCLUSIONS

Digital diagnostic imaging is the sine qua non in implant dentistry. Image acquisition protocols must be tailored to the patient's needs and clinical indication, considering the trade-off between radiation exposure and needed information. growing evidence supporting the benefits of digital workflows, from planning to execution, and the future of implant dentistry will likely involve a synergy between human expertise and AI-driven intelligence. Transiting into ionising-radiation-free imaging modalities is feasible, but these must be further developed before clinical implementation.

Performance of different cone-beam computed tomography scan modes with and without metal artifact reduction in detection of recurrent dental caries under various restorative materials

Purpose

We aimed to compare the diagnostic performance of different cone-beam computed tomography (CBCT) scan modes with and without the application of a metal artifact reduction (MAR) option under 5 different restorative materials.

Material and methods

Our research was an in vitro study with 150 caries-free premolars and molars. The teeth were randomly divided into experimental (with artificially induced caries, n = 75) and control (without caries, n = 75) groups and were prepared based on 5 types of restorative materials, including conventional composites (Filtek Z250, Gradia), flow composite, glass ionomer, and amalgam. The teeth were examined under 2 CBCT scan modes (high-resolution [HIRes] and standard) with and without MAR application. Finally, the diagnostic accuracy index values (area under the receiver operating characteristic curve [AUC], sensitivity, and specificity) were calculated.

Results

The AUC of standard scan mode with the MAR option was significantly lower than that of HIRes with MAR (p = 0.018) and without MAR option (p = 0.011) in detecting recurrent caries. Also, without MAR option, the diagnostic accuracy (AUC) of the standard mode was significantly lower than that of the HIRes (p = 0.020). Similar findings were observed for sensitivity and specificity. Moreover, diagnostic performance of standard and HIRes scan modes with and without MAR in the amalgam group was lower than that in other restorative material groups.

Conclusions

Diagnostic performance of HIRes CBCT mode was higher than that of standard mode for recurrent caries and remained unaffected by MAR application. However, the accuracy in detecting recurrent caries was lower in the amalgam group compared with other restorative material groups.

Diagnostic methods/parameters to monitor peri-implant conditions

The diagnostic accuracy of clinical parameters, including visual inspection and probing to monitor peri-implant conditions, has been regarded with skepticism. Scientific evidence pointed out that primary diagnostic tools (chairside) seem to be highly specific, while their sensitivity is lower compared with their use in monitoring periodontal stability. Nonetheless, given the association between pocket depth at teeth and implant sites and the aerobic/anaerobic nature of the microbiome, it seems plausible for pocket probing depth to be indicative of disease progression or tissue stability. In addition, understanding the inflammatory nature of peri-implant diseases, it seems reasonable to advocate that bleeding, erythema, ulceration, and suppuration might be reliable indicators of pathology. Nevertheless, single spots of bleeding on probing may not reflect peri-implant disease, since implants are prone to exhibit bleeding related to probing force. On the other side, bleeding in smokers lacks sensitivity owing to the decreased angiogenic activity. Hence, the use of dichotomous scales on bleeding in the general population, in contrast to indices that feature profuseness and time after probing, might lead to false positive diagnoses. The definitive distinction between peri-implant mucositis and peri-implantitis, though, relies upon the radiographic evidence of progressive bone loss that can be assessed by means of two- and three-dimensional methods. Accordingly, the objective of this review is to evaluate the existing clinical and radiographic parameters/methods to monitor peri-implant conditions.

Radiographic assessment of the peri-implant site

While peri-implant mucositis relies solely on clinical parameters, radiological assessment becomes indispensable for diagnosing peri-implantitis. Intraoral radiography, with its simplicity of application, low radiation exposure, and adequate representation of peri-implant structures, stands out as the standard of care for both immediate and follow-up assessments. Standardization by custom-made radiologic splints allows for excellent comparability with previous images and allows for the determination of even small changes in contour and density of the peri-implant bone. Furthermore, other radiographic modalities like panoramic radiography and cone beam computed tomography (CBCT) may provide useful features for specific patients and clinical cases while also showing innate limitations. Beyond the assessment of the marginal peri-implant bone level as the crucial parameter of clinical relevance, radiologic assessment may reveal various other findings related to the prosthetic restoration itself, the precision of its fit to the implant, and the peri-implant soft and hard tissues. Since such findings can be crucial for the assessment of peri-implant health and the implants' prognosis, a systematic diagnostic evaluation pathway for a thorough assessment is recommended to extract all relevant information from radiologic imaging. This article also provides an overview of the clinical and chronological indications for different imaging modalities in peri-implant issues.

Feasibility of frozen soft tissues to simulate fresh soft tissue conditions in cone beam CT scans

OBJECTIVES

To evaluate the feasibility of frozen soft tissues in simulating fresh soft tissues of pig mandibles using cone beam CT (CBCT).

METHODS

Two fresh pig mandibles with soft tissues containing 2 tubes filled with a radiopaque homogeneous solution were scanned using 4 CBCT units and 2 field-of-view (FOV) sizes each. The pig mandibles were deep-frozen and scanned again. Three cross-sections were exported from each CBCT volume and grouped into pairs, with one cross-section representing a fresh and one a frozen mandible. Three radiologists compared the pairs and attributed a score to assess the relative image quality using a 5-point scale. Mean grey values and standard deviation were obtained from homogeneous areas in the tubes, compared using the Wilcoxon matched-pair signed-rank test and subjected to Pearson correlation analysis between fresh and frozen physical states (α = .05).

RESULTS

Subjective evaluation revealed similarity of the CBCT image quality between fresh and frozen states. The distribution of mean grey values was similar between fresh and frozen states. Mean grey values of the frozen state in the small FOV were significantly greater than those of the fresh state (P = .037), and noise values of the frozen state in the large FOV were significantly greater than those of the fresh state (P = 0.007). Both mean grey values and noise exhibited significant and positive correlations between fresh and frozen states (P < 0.01).

CONCLUSIONS

The freezing of pig mandibles with soft tissues may serve as a method to prolong their usability and working time when CBCT imaging is planned.

Effect of industrial scanner and framework material interaction on the marginal gaps of CAD-CAM complete arch implant frameworks

STATEMENT OF PROBLEM

Structured-light and computed tomography industrial scanners have been used as reference scanners to measure marginal gaps between implants and superstructures. However, the effect of framework material on the scanners' ability to detect gaps and on precision has not yet been evaluated.

PURPOSE

The purpose of this in vitro study was to investigate the interaction between the industrial scanner and framework material on measured marginal gaps of implant-supported fixed complete arch frameworks made from titanium and polymethylmethacrylate and on the precision of scans.

MATERIAL AND METHODS

A completely edentulous maxillary model with 4 implants and multiunit abutments at the first molar and canine sites was digitized by using a laboratory scanner. Implant-supported frameworks were milled from titanium and polymethylmethacrylate (n=5). Each framework was secured on the left molar site abutment. The marginal gaps between the frameworks and abutment sites without a screw were measured by using an industrial structured-light scanner and an industrial computed tomography scanner. The effect of the scanner, the framework material, and their interaction on measured gaps was analyzed by applying linear regressions and weighted least square methods. The F-statistics was used with Bonferroni corrections for precision analysis (α=.05).

RESULTS

No significant effect of scanner, material, or their interaction was found on the marginal gaps at the canine sites. The titanium framework gaps detected by using the computed tomography scanner were greater than those detected by using the structured-light scanner at the right molar site (estimated difference in means=0.054 mm; P=.003) and overall (estimated difference in means=0.023 mm; P=.033). The structured-light scanner's precision was higher than that of the computed tomography scanner when titanium frameworks were scanned (P=.001). The computed tomography scanner's precision was higher when scanning polymethylmethacrylate frameworks than when scanning titanium frameworks (P=.03).

CONCLUSIONS

Framework material and industrial scanner interaction affected the measured gaps. The computed tomography scanner detected greater marginal gaps with low precision when scanning titanium frameworks than the structured-light scanner. The sample size, the use of only 2 types of materials, and a laboratory scanner to obtain the computer-aided design file should be considered when interpreting the results.

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.

Deep learning-based segmentation of dental implants on cone-beam computed tomography images: A validation study

OBJECTIVES

To train and validate a cloud-based convolutional neural network (CNN) model for automated segmentation (AS) of dental implant and attached prosthetic crown on cone-beam computed tomography (CBCT) images.

METHODS

A total dataset of 280 maxillomandibular jawbone CBCT scans was acquired from patients who underwent implant placement with or without coronal restoration. The dataset was randomly divided into three subsets: training set (n = 225), validation set (n = 25) and testing set (n = 30). A CNN model was developed and trained using expert-based semi-automated segmentation (SS) of the implant and attached prosthetic crown as the ground truth. The performance of AS was assessed by comparing with SS and manually corrected automated segmentation referred to as refined-automated segmentation (R-AS). Evaluation metrics included timing, voxel-wise comparison based on confusion matrix and 3D surface differences.

RESULTS

The average time required for AS was 60 times faster (<30 s) than the SS approach. The CNN model was highly effective in segmenting dental implants both with and without coronal restoration, achieving a high dice similarity coefficient score of 0.92±0.02 and 0.91±0.03, respectively. Moreover, the root mean square deviation values were also found to be low (implant only: 0.08±0.09 mm, implant+restoration: 0.11±0.07 mm) when compared with R-AS, implying high AI segmentation accuracy.

CONCLUSIONS

The proposed cloud-based deep learning tool demonstrated high performance and time-efficient segmentation of implants on CBCT images.

CLINICAL SIGNIFICANCE

AI-based segmentation of implants and prosthetic crowns can minimize the negative impact of artifacts and enhance the generalizability of creating dental virtual models. Furthermore, incorporating the suggested tool into existing CNN models specialized for segmenting anatomical structures can improve pre-surgical planning for implants and post-operative assessment of peri‑implant bone levels.

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.

The Effect of Changes in the Angular Position of Implants on Metal Artifact Reduction in Cone-Beam Computed Tomography Images: A Scoping Review

Objective

Dental implant artifacts can compromise the quality of cone-beam computed tomography (CBCT) scans and challenge radiographic detection in surrounding regions. This literature review was conducted to examine the impact of implant angle modification on reducing metal artifacts in CBCT scans.

Materials and Methods

A scoping review of literature was carried out in PubMed, Embase, Scopus, and Cochrane databases.

Results

Different spatial planes, including alpha, beta, gamma, and phi, along with 0°, 5.2°, 9.8°, 14.5°, 15°, 30°, 45°, 60°, 75°, and 90° angles were studied. Changes in the angular position of implants may reduce metal artifacts and improve the quality of CBCT scans.

Conclusions

Rotating implants within the alpha plane and angling them at 90° in the alpha plane enables reducing dental implant artifacts.

Influence of metal artefact reduction on the diagnosis of contact between implant and mandibular canal in cone beam computed tomography: An ex-vivo study

OBJECTIVE

To evaluate the influence of metal artefact reduction (MAR) in the diagnosis of dental implant contact with the mandibular canal (MC) using cone beam computed tomography (CBCT).

METHODS

Dental implants were installed with surgical guides in the posterior hemiarches of 10 dry human mandibles: 0.5 mm above to the MC cortex (G1/n = 8) and 0.5 mm inside the MC (G2/n = 10). The experimental set-up was scanned with two CBCT equipment using 85 kV and 90 kV, MAR ON or OFF, and different tube currents (4 mA, 8 mA and 10 mA). Two dentomaxillofacial radiologists (DMFRs) and two dentists (DDS) scored the relation between the dental implant and MC. Descriptive statistics were used to observe the absolute frequency of scores. Sensitivity, specificity and accuracy were calculated considering the known relation between the dental implant and the MC interior. McNemar's test (α = .05) was applied to compare the diagnostic efficacy of MAR ON versus MAR OFF.

RESULTS

Overall specificity was higher than sensitivity for both DDS and DMFR (97% vs. 50% and 92.0% vs. 78.0% respectively). There was a significant effect of MAR (p = .031) for DMFR in the case of contact between the dental implant with the MC interior, in which sensitivity decreased with MAR activation from 90% to 40%. DMFR observers showed a better diagnostic performance compared with the DDS observers (accuracy of 84.0% and 71.0%, respectively).

CONCLUSIONS

Due to the limited efficacy of MAR, it should not be used when conducting CBCT scans for the evaluation of contact between the implant and the mandibular canal.

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.

The impact of implant-related characteristics on dental implant blooming: An in vitro study

AIM

To assess, in vitro, variables potentially influencing implant blooming using a human-like imaging phantom and 3D-printed mandibles.

MATERIAL AND METHODS

Sixty implants were inserted in 3D-printed mandibles in 26 different configurations in order to examine the impact of implant diameter, presence of a cover screw, implant design/material, implant position, and the presence of additional implants on implant blooming using two cone-beam computed tomography (CBCT) devices (Accuitomo [ACC] and NewTom [NWT]). Two observers measured the amount of implant blooming in both buccolingual and mesiodistal directions. Inter-rater agreement and descriptive statistics, grouped by implant characteristic and CBCT device, were calculated.

RESULTS

Both CBCT devices increased implant diameter (a mean increase of 9.2% and 11.8% for titanium, 20.3% and 24.4% for zirconium, for ACC and NWT, respectively). An increase in implant diameter did not increase the amount of blooming, whereas placing a cover screw did (from 8.0% to 10.9% for ACC, and from 10.0% to 15.6% for NWT). Moreover, implant design, anatomical region, and the presence of another implant also affected the extent of the blooming.

CONCLUSIONS

Dental implants show a clear diameter increase on CBCT, with the effect being more pronounced for zirconium than for titanium implants. Similar effects are likely to occur in the clinical setting, potentially masking nonosseointegration, reducing the dimensions of peri-implant defects, and/or causing underestimation of the buccal bone thickness.

Accuracy of intraoral real-time navigation versus static, CAD/CAM-manufactured pilot drilling guides in dental implant surgery: an in vitro study

Background

Nowadays, 3D planning and static for dynamic aids play an increasing role in oral rehabilitation of the masticatory apparatus with dental implants. The aim of this study is to compare the accuracy of implant placement using a 3D-printed drilling guide and an intraoral real-time dynamic navigation system.

Methods

A total of 60 implants were placed on 12 partially edentulous lower jaw models. 30 were placed with pilot drilling guides, the other half with dynamic navigation (DENACAM^®). In addition, implant placement in interdental gaps and free-end situations were investigated. Accuracy was assessed by cone-beam computed tomography (CBCT).

Results

Both systems achieved clinically acceptable results, yet more accurate results regarding the offset of implant base and tip in several spatial dimensions were achieved using drilling guides (each p < 0.05). With regard to angulation, real-time navigation was more precise (p = 0.0016). Its inaccuracy was 3°; the template-guided systems was 4.6°. Median horizontal deviation was 0.52 mm at base and 0.75 mm at tip using DENACAM^®. When using the pilot drill guide, horizontal deviation was 0.34 mm in the median and at the tip by 0.59 mm. Regarding angulation, it was found that the closer the drill hole was to the system's marker, the better navigation performed. The template did not show this trend (p = 0.0043; and p = 0.0022).

Conclusion

Considering the limitations of an in vitro study, dynamic navigation can be used be a tool for reliable and accurate implantation. However, further clinical studies need to follow in order to provide an evidence-based recommendation for use in vivo.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40729-022-00430-6.

Accuracy of digitally fabricated drilling guide to form screw-access channels in cement-retained implant prostheses: A randomized clinical trial

STATEMENT OF PROBLEM

Accurate intraoral preparation of screw channels in cement-retained implant prostheses could be a treatment challenge for tilted or badly positioned implants.

PURPOSE

The purpose of this randomized clinical trial was to evaluate screw channel accuracy for retrieving cement-retained implant prostheses by using a digitally fabricated drilling guide.

MATERIAL AND METHODS

Twenty-four participants requiring removal of cement-retained implant prostheses were recruited and consecutively assigned to 1 of 2 groups. In the first group, drilling guides were fabricated by using an intraoral scan, computer-aided design (CAD), and 3D printing to facilitate screw channel preparation (guide group). In the second group, screw channel preparation was based on panoramic radiographs without a drilling guide (freehand group). Screw channel accuracy was evaluated with a 3D analysis and subsequently compared with the ideal shape of the screw channel for linear deviation at coronal and apical levels, angular deviation, surface loss deviation, and volume loss deviation. The ideal shape of the screw-access channel was based on the Ø2.2-mm cylinder image marked along the long axis of the implant. The Mann-Whitney U and Kruskal-Wallis tests were used for statistical analyses (α=.05).

RESULTS

The drilling guide group showed higher dimensional accuracy than the freehand group for angular deviation (9.45 degrees versus 15.69 degrees; P=.014) and surface loss deviation (7.40 mm versus 9.53 mm; P=.001), especially when the implant was tilted more than 30 degrees. The deviation values of the screw channels were not significantly different according to implant tilt in either group (P>.05).

CONCLUSIONS

Digitally fabricated drilling guides for intraoral preparation of screw channels in cement-retained implant prostheses can improve accuracy and provide a less-destructive screw channel.

Bone preservation or augmentation simultaneous with or prior to dental implant placement: A systematic review of outcomes and outcome measures used in clinical trials in the last 10 years

AIM

To evaluate outcome measures and methods of assessment in clinical studies on bone augmentation/preservation procedures for the placement of dental implants.

MATERIALS AND METHODS

A systematic search was performed on three databases from January 2011 to April 2021 to identify clinical studies reporting on any type of bone augmentation/preservation procedure. The outcomes that have been used to assess efficacy or performance in each study were registered and assigned to different domains (group of outcomes). The review followed the Preferred Reporting Items for Systematic Review and Meta-Analyses statement.

RESULTS

Seven-hundred and eighty-three publications were included. Only 81.8% of the papers had a clear definition of their primary outcome. The rate of complications (59.3%), implant survival (58.2%), 3D radiographic bone gain/change (30%), marginal bone level (MBL; 29%), and histological outcomes (25.5%) were the most frequently reported outcome domains. The most commonly used primary outcome was 3D radiographic bone gain/change (25.8%), followed by implant survival (13.0%). Patient-reported outcome measures (PROMs) were reported in 15.7% of studies. Differences in the reported outcomes were observed among different types of bone preservation/augmentation interventions (i.e., alveolar ridge preservation, immediate implants, horizontal and/or vertical ridge augmentation, and sinus floor augmentation).

CONCLUSION

Within the past decade, great heterogeneity was observed among the outcomes considered in studies evaluating bone preservation/augmentation procedures. Three-dimensional radiographic bone gain/change was the most routinely reported main outcome variable, while PROMs were rarely reported.

Bone preservation or augmentation simultaneous with or prior to dental implant placement: A systematic review of outcomes and outcome measures used in clinical trials in the last 10 years

AIM

To evaluate outcome measures and methods of assessment in clinical studies on bone augmentation/preservation procedures for the placement of dental implants.

MATERIALS AND METHODS

A systematic search was performed on three databases from January 2011 to April 2021 to identify clinical studies reporting on any type of bone augmentation/preservation procedure. The outcomes that have been used to assess efficacy or performance in each study were registered and assigned to different domains (group of outcomes). The review followed the Preferred Reporting Items for Systematic Review and Meta-Analyses statement.

RESULTS

Seven-hundred and eighty-three publications were included. Only 81.8% of the papers had a clear definition of their primary outcome. The rate of complications (59.3%), implant survival (58.2%), 3D radiographic bone gain/change (30%), marginal bone level (MBL; 29%), and histological outcomes (25.5%) were the most frequently reported outcome domains. The most commonly used primary outcome was 3D radiographic bone gain/change (25.8%), followed by implant survival (13.0%). Patient-reported outcome measures (PROMs) were reported in 15.7% of studies. Differences in the reported outcomes were observed among different types of bone preservation/augmentation interventions (i.e., alveolar ridge preservation, immediate implants, horizontal and/or vertical ridge augmentation, and sinus floor augmentation).

CONCLUSION

Within the past decade, great heterogeneity was observed among the outcomes considered in studies evaluating bone preservation/augmentation procedures. Three-dimensional radiographic bone gain/change was the most routinely reported main outcome variable, while PROMs were rarely reported.

Accuracy evaluation of cone beam computed tomography applied to measure peri-implant bone thickness in living patients: an ex vivo and in vivo experiment

OBJECTIVES

This study aims to study the accuracy of cone beam computed tomography (CBCT) for measuring peri-implant bone thickness in living patients via a novel visualization method (NVM).

MATERIAL AND METHODS

The validity of the NVM was verified ex vivo by measuring the same peri-implant bone thicknesses in bovine ribs by using raw postoperative CBCT (clinical measurement, CM), the visualized fused images obtained using the NVM (visualized fused measurement, VF), and hard tissue sections (gold standard measurement, GS). The NVM was applied by deconstructing the postoperative CBCT model into the Model_post-bone and Model_implant and replacing it with bone from preoperative CBCT and standard implant models, respectively. In vivo, 52 implants were included, and the VF of each implant was obtained using data processing methods similar to those used ex vivo. Then, we compared the results of CM and VF.

RESULTS

Ex vivo, the VF was similar to GS, while CM usually underestimated the peri-implant bone thickness, especially at the implant shoulder (P < 0.01). In vivo, on CBCT, areas with a peri-implant bone thickness of 0-0.50 mm were not visible, while those with a thickness of 0.50-1.00 mm were occasionally visible. There was less underestimation of bone along the implant long axis.

CONCLUSIONS

Thin peri-implant bones could be completely underestimated on CBCT. CBCT scans alone are insufficient to warrant surgical intervention. Our NVM facilitates the accurate visual assessment of implant dimensions.

CLINICAL RELEVANCE

The thickness of peri-implant bone could be completely underestimated when thinner than 1.0 mm in living patients. Familiarity with these confusing CBCT results may help clinicians and patients avoid further unnecessary evaluation, misdiagnosis, and invasive treatment.

In Vitro Quantitative Evaluation of Postprocessing Filter for Metal Artifact Reduction in Cone Beam Computed Tomography Images of Titanium and Zirconium Dioxide Implants

Objective

To evaluate a postprocessing filter of a new imaging-processing software for analysis of metal artifact reduction.

Methods

Eight artificial edentulous mandibles (phantoms), where titanium and zirconium dioxide implants had been installed in four different regions (i.e., incisors, canine, premolars, and molars). CBCT volume was acquired, and then, four types of filters were applied to the images: BAR filter and Multi-CDT NR filter (e-Vol DX) and Sharpening Filters 1x and 2x (OnDemand). Artifact was assessed by measuring the standard deviation (SD) of the gray values of filtered and unfiltered images. The comparison between implant material, teeth, and filters was performed by using ANOVA, whereas multiple comparisons were performed by using Bonferroni's test. The level of significance adopted was 5%.

Results

The results showing higher SD values, which suggests a worse image, were obtained with titanium implants compared to zirconium dioxide ones. With regard to the four filters used, it can be seen that the lowest SD values were obtained with BAR and Multi-CDT NR filters and the highest with Sharpening Filters 1x and 2x, with no statistical difference between them, except regarding the molar region in titanium implants.

Conclusion

The highest SD values were seen in zirconium dioxide implants, mainly in the region of anterior teeth. The BAR filter was found to be the most effective as its SD value decreased significantly, indicating that the image quality was improved.

Accuracy of bone level assessments following reconstructive surgical treatment of experimental peri-implantitis

AIMS

The purpose was to evaluate the accuracy of bone level assessments using either cone beam computed tomography, intraoral periapical radiographs or histology following reconstructive treatment of experimental peri-implantitis.

MATERIALS AND METHODS

Six Labrador dogs were used. Experimental peri-implantitis was induced 3 months after implant placement. Surgical treatment of peri-implantitis was performed and peri-implant defects were allocated to one of four treatment categories; no augmentation, bone graft materials with or without a barrier membrane. Six months later, intraoral periapical radiographs and block biopsies from all implants sites were obtained. Marginal bone levels were measured using periapical radiographs, CBCT and histology.

RESULTS

Significant correlations of MBL assessments were observed between the three methods. The measurements in periapical radiographs consistently resulted in an overestimation of the bone level of about 0.3 - 0.4 mm. The agreement between methods was not influenced by the use of bone substitute materials in the management of the osseous defects.

CONCLUSIONS

Although MBL assessments obtained from PA radiographs showed an overestimation compared to MBL assessments on corresponding CBCT images and histological sections, PA radiographs can be considered a reliable technique for peri-implant bone level evaluations following reconstructive surgical therapy of experimental peri-implantitis.

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.

Influence of kilovoltage-peak and the metal artifact reduction tool in cone-beam computed tomography on the detection of bone defects around titanium-zirconia and zirconia implants

Purpose

The aim of this study was to assess the influence of kilovoltage-peak (kVp) and the metal artifact reduction (MAR) tool on the detection of buccal and lingual peri-implant dehiscence in the presence of titanium-zirconia (Ti-Zr) and zirconia (Zr) implants in cone-beam computed tomography (CBCT) images.

Materials and Methods

Twenty implant sites were created in the posterior region of human mandibles, including control sites (without dehiscence) and experimental sites (with dehiscence). Individually, a Ti-Zr or Zr implant was placed in each implant site. CBCT scans were performed using a Picasso Trio device, with variation in the kVp setting (70 or 90 kVp) and whether the MAR tool was used. Three oral radiologists scored the detection of dehiscence using a 5-point scale. The area under the receiver operating characteristic (ROC) curve, sensitivity, and specificity were calculated and compared by multi-way analysis of variance (α=0.05).

Results

The kVp, cortical plate involved (buccal or lingual cortices), and MAR did not influence any diagnostic values (P>0.05). The material of the implant did not influence the ROC curve values (P>0.05). In contrast, the sensitivity and specificity were statistically significantly influenced by the implant material (P<0.05) with Zr implants showing higher sensitivity values and lower specificity values than Ti-Zr implants.

Conclusion

The detection of peri-implant dehiscence was not influenced by kVp, use of the MAR tool, or the cortical plate. Greater sensitivity and lower specificity were shown for the detection of peri-implant dehiscence in the presence of a Zr implant.

Dimensional changes of buccal bone in the edentulous maxilla with telescopic-retained implant-supported fixed dental prostheses

STATEMENT OF PROBLEM

The buccal bone in an edentulous maxilla loses thickness over time because of physiological changes. However, the dimensional changes of the buccal bone in an edentulous maxilla with an implant-supported fixed dental prosthesis are unknown.

PURPOSE

The purpose of this retrospective clinical study was to evaluate cone beam computed tomography (CBCT) images of the dimensional changes of the buccal bone in edentulous maxillae with complete-arch telescopic-retained implant-supported fixed dental prostheses (CTI-FDPs) after 6 years by using a professional retrieval system.

MATERIAL AND METHODS

This study included 17 participants with edentulous maxillae who had been provided with CTI-FDP with 121 taper joint implants. A three-dimensional radiographic analysis by using CBCT was performed at implant insertion (0 years) and after 6 years. Vertical and horizontal bone measurement values were evaluated. During horizontal bone thickness measurement, 4 different levels, 0, 2, 4, and 6 mm apical to the implant shoulder, were evaluated as bone value (BV)_0mm, BV_2mm, BV_4mm, and BV_6mm, respectively. The BVs were compared with the Wilcoxon signed-rank test and Kruskal-Wallis test (α=.05). In addition, the Spearman rank correlation coefficient was used to identify 0yBV factors that influence the 6yBVs. A nonlinear regression analysis was used to clarify the slopes of 0yBVs and 6yBV_0mm.

RESULTS

Significant decreases in vertical and horizontal BVs were found between 0 years and 6 years (P<.05). However, no significant difference was observed in bone loss at 6 years at any of the vertical and horizontal measurement points (P≥.05). When 0yBVs related to 6yBV_0mm were analyzed, 0yBV_0mm and 0yBV_2mm showed strong correlations with 6yBV_0mm (|r|≥.7). In the regression analysis, a 0yBV_0mm of 0.58 mm and 0yBV_2mm of 0.78 mm could be critical factors associated with a 6yBV_0mm of 0 mm. A 6yBV_0mm of 0yBV_0mm more than 0.58 mm was significantly higher than a 6yBV_0mm of 0yBV_0mm less than 0.58 mm (P<.001). Moreover, a 6yBV_0mm of 0yBV_2mm more than 0.78 mm was significantly higher than a 6yBV_0mm of 0yBV_2mm less than 0.78 mm (P<.001).

CONCLUSIONS

The buccal bone in an edentulous maxilla with fixed implant-supported prostheses lost significant vertical and horizontal bone thicknesses after 6 years. At implant insertion, both a 0.58-mm buccal bone on the platform and a 0.78-mm buccal bone at 2 mm apical to the implant shoulder are necessary for longer term maintenance of bone on the platform of implants specifically supporting CTI-FDPs.

Diagnostic performance of periapical and panoramic radiography and cone beam computed tomography for detection of circumferential gaps simulating osseointegration failure around dental implants: A systematic review

OBJECTIVE

The objective of this study was to appraise the diagnostic performance of periapical (PR) and panoramic (PANO) radiographs and cone beam computed tomography (CBCT) in detecting artificial circumferential gaps simulating osseointegration failure around dental implants in ex vivo studies.

STUDY DESIGN

Seven electronic databases and three gray literature sources were searched. Studies reporting diagnostic performance measures or data allowing calculation of those measures compared with the reference standard of in situ direct measurements were considered eligible. Either the area under the receiver operating characteristic curve or accuracy was chosen to summarize findings, with diagnostic performance interpreted as poor, acceptable, excellent, or outstanding. Risk of bias (RoB) was also assessed.

RESULTS

The ten included studies mostly suggested overall excellent to outstanding diagnostic capability with PR and CBCT. Various enhancement filters, CBCT voxel sizes, and/or fields of view were associated with acceptable to outstanding efficacy. PANO had the poorest results, with most research demonstrating acceptable to excellent discrimination. The RoB was high for seven studies, moderate for two, and low for -one.

CONCLUSIONS

PR and CBCT images were generally superior to PANO for the detection of artificial bone gaps. Results should be interpreted with caution because most studies had a high RoB.

Comprehensive peri-implant tissue evaluation with ultrasonography and cone-beam computed tomography: A pilot study

OBJECTIVES

The aim of the present study was to explore the feasibility of ultrasonography (US) for clinical imaging of peri-implant tissues.

MATERIAL AND METHODS

Patients with ≥1 implant, a cone-beam computed tomography (CBCT) scan, an US scan, and clinical photographs taken during the surgery were included. The crestal bone thickness (CBT) and facial bone level (FBL) were measured on both US and CBCT modalities, and direct FBL measurements were also made on clinical images. US measurements were compared with CBCT and direct readings.

RESULTS

A total of eight implants from four patients were included. For FBL measurements, US and direct (r2 = 0.95) as well as US and CBCT (r2 = 0.85) were highly correlated, whereas CBCT correlated satisfactorily with the direct reading (r2 = 0.75). In one implant without facial bone, CBCT was not able to measure CBT and FBL accurately. The estimated bias for CBT readings was 0.17 ± 0.23 mm (p = .10) between US and CBCT. US blood flow imaging was successfully recorded and showed a wide dynamic range among patients with different degrees of clinical inflammation.

CONCLUSION

US is a feasible method to evaluate peri-implant facial crestal bone dimensions. Additional US features, for example, functional blood flow imaging, may be useful to estimate the extent and severity of inflammation.

Quantitative analysis of metal artefacts of dental implant in CBCT image by correlation analysis to micro-CT: A microstructural study

OBJECTIVES

Quantification of dental implant metal artefacts in CBCT images using correlation analysis of trabecular microstructural parameters from CBCT and micro-CT, and analysis of the effect of varying the angular position of the subject.

METHODS

Polyurethane synthetic bone blocks were first scanned without implants by micro-CT and CBCT. Two dental implants were then placed parallel in the bone blocks and these specimens were scanned by CBCT with different alpha angles. Three volumes of interest (VOI) were set for further analysis. Six microstructural parameters were measured: trabecular thickness (Tb_Th), trabecular spacing (Th_Sp), bone volume per total volume (BV/TV), bone surface per total volume (BS/TV), connectivity density (CD) andfractal dimension (FD). Micro-CT measurements were used as a gold standard for CBCT. Spearman correlation coefficients for each microstructural parameter from CBCT and micro-CT were calculated and compared using Steiger's Z test.

RESULTS

Without the implants, in VOI₁, the Spearman correlation coefficients of Tb_Th, Tb_Sp, BV/TV, BS/TV, CD and FD were 0.599, 0.76, 0.552, 0.566, 0.664 and 0.607, respectively. With the implants, the correlation coefficients decreased sharply in VOI₁. As the alpha angle increased from zero to 90°, the correlation coefficients increased and became significant. Similar results appeared in VOI₂. In contrast, in VOI₃, the correlation coefficient decreased as the alpha angle increased.

CONCLUSIONS

Metal artefacts were successfully quantified using microstructural parameters in terms of the image quality of the CBCT. Changes in alpha angle affected the quality of the CBCT image.