High-resolution 3D ultrasound jawbone surface imaging for diagnosis of periodontal bony defects: an in vitro study. Ann Biomed Eng. 2010;38:3409-3422. [PMID: 20532630 DOI: 10.1007/s10439-010-0089-0]

Accuracy of intraoral ultrasound to evaluate alveolar bone level: an ex vivo study in human cadavers

OBJECTIVES

This study aimed to evaluate the reliability and accuracy of an intraoral ultrasound (US) device to evaluate alveolar bone by comparing it between different raters and to microCT (µCT) measurements.

METHODS

38 teeth distributed across three human cadavers were prepared by placing two notches on the facial enamel surface. The maxillary and mandibular teeth were imaged with a custom-designed intraoral 20 MHz ultrasound and µCT with 0.03 mm voxel size. µCT was considered the reference standard for this study. For each sample, the distance from the inferior border of the most apical notch to the tip of the alveolar bone crest on the facial aspect of the teeth was measured from the US and µCT images. Intraclass correlation coefficient (ICC) and standard deviation were calculated.

RESULTS

The intra-examiner and inter-examiner reliability for both the µCT and US alveolar bone measurements were found to be excellent (intra-examiner ICC was 0.998 for µCT and 0.997 for US, inter-examiner ICC was 0.996 for µCT and between 0.947 and 0.950 for US). The accuracy of the US was found to be good compared to µCT (ICC between 0.885 and 0.894).

CONCLUSION

The study demonstrated that intraoral ultrasound is highly reliable and accurate compared to the µCT reference standard for evaluating facial alveolar bone height.

Assessment of periodontal dehiscence and fenestration using ultrasonography and cone-beam computed tomography: an in vitro study

OBJECTIVES

This study sought to assess the diagnostic value of ultrasonography (USG) and cone-beam computed tomography (CBCT) for the visibility of periodontal defects.

MATERIALS AND METHODS

We created 37 periodontal defects (dehiscence and fenestration) in fresh sheep mandibles. Two dentomaxillofacial radiologists assessed the CBCT and ultrasonographic images for the presence of defects. Kappa statistics was used for evaluating the inter- and intra-observer agreement. Sensitivity, specificity, diagnostic accuracy, positive predictive value (PPV), and negative predictive value (NPV) for each radiographic technique were calculated.

RESULTS

Interobserver evaluations revealed moderate and good agreement for USG and very good agreement for CBCT in visibility of dehiscences and fenestrations. It has been determined that USG and CBCT have similar sensitivity and specificity values.

CONCLUSIONS

USG can be used as an alternative diagnostic method to CBCT in the evaluation of periodontal defects.

CLINICAL RELEVANCE

This study has shown that USG can be an alternative diagnostic method to CBCT in imaging dehiscence and fenestration in the alveolar bone, which is the hard tissue component of the jaws. In addition to clinical probing, USG, which is a radiation-free imaging method, can be used to provide additional information in the visibility of defects. Such studies will increase the experience and knowledge of physicians and will allow USG to take a greater place in dental practice.

Ultrasonic mapping of midpalatal suture - An ex-vivo study

OBJECTIVE

Rapid maxillary expansion is a common orthodontic procedure to correct maxillary constriction. Assessing the midpalatal suture (MPS) expansion plays a crucial role in treatment planning to determine its effectiveness. The objectives of this preliminary investigation are to demonstrate a proof of concept that the palatal bone underlying the rugae can be clearly imaged by ultrasound (US) and the reconstructed axial view of the US image accurately maps the MPS patency.

METHODS

An ex-vivo US scanning was conducted on the upper jawbones of two piglet's carcasses before and after the creation of bone defects, which simulated the suture opening. The planar images were processed to enhance bone intensity distribution before being orderly stacked to fuse into a volume. Graph-cut segmentation was applied to delineate the palatal bone to generate a bone volume. The accuracy of the reconstructed bone volume and the suture opening was validated by the micro-computed tomography (µCT) data used as the ground truth and compared with cone beam computed tomography (CBCT) data as the clinical standard. Also included in the comparison is the rugae thickness. Correlation and Bland-Altman plots were used to test the agreement between the two methods: US versus µCT/CBCT.

RESULTS

The reconstruction of the US palatal bone volumes was accurate based on surface topography comparison with a mean error of 0.19 mm for pre-defect and 0.15 mm and 0.09 mm for post-defect models of the two samples, respectively when compared with µCT volumes. A strong correlation (R2 ≥ 0.99) in measuring MPS expansion was found between US and µCT/CBCT with MADs of less than 0.05 mm, 0.11 mm and 0.23 mm for US, µCT and CBCT, respectively.

CONCLUSIONS

It was possible to axially image the MPS opening and rugae thickness accurately using high-frequency ultrasound.

CLINICAL SIGNIFICANCE

This study introduces an ionizing radiation-free, low-cost, and portable technique to accurately image a difficult part of oral cavity anatomy. The advantages of conceivable visualization could promise a successful clinical examination of MPS to support the predictable treatment outcome of maxillary transverse deficiency.

Overview of Ultrasound in Dentistry for Advancing Research Methodology and Patient Care Quality with Emphasis on Periodontal/Peri-implant Applications

BACKGROUND

Ultrasound is a non-invasive, cross-sectional imaging technique emerging in dentistry. It is an adjunct tool for diagnosing pathologies in the oral cavity that overcomes some limitations of current methodologies, including direct clinical examination, 2D radiographs, and cone beam computerized tomography. Increasing demand for soft tissue imaging has led to continuous improvements on transducer miniaturization and spatial resolution. The aims of this study are (1) to create a comprehensive overview of the current literature of ultrasonic imaging relating to dentistry, and (2) to provide a view onto investigations with immediate, intermediate, and long-term impact in periodontology and implantology.

METHODS

A rapid literature review was performed using two broad searches conducted in the PubMed database, yielding 576 and 757 citations, respectively. A rating was established within a citation software (EndNote) using a 5-star classification. The broad search with 757 citations allowed for high sensitivity whereas the subsequent rating added specificity.

RESULTS

A critical review of the clinical applications of ultrasound in dentistry was provided with a focus on applications in periodontology and implantology. The role of ultrasound as a developing dental diagnostic tool was reviewed. Specific uses such as soft and hard tissue imaging, longitudinal monitoring, as well as anatomic and physiological evaluation were discussed.

CONCLUSIONS

Future efforts should be directed towards the transition of ultrasonography from a research tool to a clinical tool. Moreover, a dedicated effort is needed to introduce ultrasonic imaging to dental education and the dental community to ultimately improve the quality of patient care.

Ultrasound insonation angle and scanning imaging modes for imaging dental implant structures: A benchtop study

INTRODUCTION

High frequency ultrasound has shown as a promising imaging modality to evaluate peri-implant tissues. It is not known if the ultrasound imaging settings might influence ultrasound's ability to differentiate implant structures. The aim of this benchtop study was to evaluate the dependence of ultrasound on imaging angles and modes to measure implant geometry-related parameters.

METHODS

A clinical ultrasound scanner (ZS3, Mindray) with an intraoral probe (L30-8) offering combinations of harmonic and compound imaging modes was employed for imaging 16 abutments and 4 implants. The samples were mounted to a micro-positioning system in a water tank, which allowed a range of -30 to 30-degree imaging angles in 5-degree increment between the probe and samples. The abutment angle, implant thread pitch and depth were measured on ultrasound, compared to the reference readings. The errors were computed as a function of the image angles and modes. All samples were replicated 3 times for 3 image modes and 11 image angles, thus resulting in 2,340 images.

RESULTS

The mean errors of ultrasound to estimate 16 abutment angles, compared to the reference values, were between -1.8 to 2.7 degrees. The root mean squared error (RMSE) ranged from 1.5 to 4.6 degrees. Ultrasound significantly overestimated the thread pitch by 26.1 μm to 36.2 μm. The error in thread depth measurements were in a range of -50.5 μm to 39.6 μm, respectively. The RMSE of thread pitch and depth of the tested 4 implants was in a range of 34.7 to 56.9 μm and 51.0 to 101.8 μm, respectively. In most samples, these errors were independent of the image angle and modes.

CONCLUSIONS

Within the limitations of this study, high-frequency ultrasound was feasible in imaging abutments and implant fixtures independent of scanning angle within ±30° of normal incidence and for compounding and non-compounding-based imaging modes.

Assessment of Negative Gingival Recession: A Critical Component of Periodontal Diagnosis

Accurate measurement of negative gingival recession (GR) is essential to accurately determine the clinical attachment loss, which leads to an accurate diagnosis and optimal therapy of periodontal disease. However, the accuracy of measuring the negative GR has been shown to be low and highly variable between examiners. The position of the gingiva margin in relation to the cemento-enamel junction (CEJ) varies among different stages of passive eruption. The amount of negative GR is about 2 mm on average at the mid-facial sites and ranges from 2 to 3.5 mm at interproximal sites in periodontally healthy patients. Some other clinical conditions may change the gingival dimension coronal to the CEJ, such as altered passive eruption and gingival enlargement. In addition to the traditional approach using a periodontal probe to assess the negative GR, nowadays dental ultrasound imaging may be able to assist in accurately measuring the amount of negative GR. This narrative review will discuss the existing evidence of the dimension of dentogingival tissue and the clinical assessment of negative GR using different clinical tools.

In vitro assessment of periapical lesions created in sheep mandibles by using high resolution ultrasonography and cone beam computed tomography

OBJECTIVES

Providing ultrasound images of periapical lesions may be problematic depending on the thickness of the overlying cortical bone. Clinically, it is crucial to determine the cut-off value of overlaying bone thickness in terms of interference with ultrasound imaging in conjunction with assessment of changes in periapical jaw bone lesions. Our aim was to determine the minimum amount of overlaying buccal bone thickness of artificial periapical lesions in order to be visible by ultrasound imaging and to compare width, height, depth, surface area and volume measurements of detectable periapical lesions obtained from ultrasound and CBCT images.

METHODS

Periapical lesions were created in 16 molar teeth of sheep mandibles. Cavities were enlarged until the borders of lesions were visible on 14 MHz hockey probe ultrasound imaging. CBCT and ultrasound images were obtained simultaneously after drilling and enlarging each size of the cavities and replacing the teeth in their sockets. two observers separately assessed images twice within 2 weeks of interval. By using CBCT and ultrasound images, buccal bone thickness, maximum width, height, depth, surface area and volume of periapical lesions were measured. Intraclass correlation coefficient (ICC) was utilized and significance level was set at p < 0.05.

RESULTS

The mean buccal bone thickness ranged between 1.21 mm and 1.31 mm for both imaging techniques. For the measurement of buccal bone thickness, periapical lesion width, height, depth, surface area, and volume excellent ICC values were found in terms of intrarater (ranging between 0.907 and 1) and inter-rater (ranging between 0.864 and 1) reliability for both observers and their readings. There were no statistically significant differences for both observers and for their two readings between ultrasound and CBCT measurements of buccal bone thickness, and periapical lesion width and height (p > 0.05).

CONCLUSIONS

We suggested that a buccal thickness of approximately 1.28 mm might be accepted as a cut-off value for the detection of periapical lesions with 14 MHz hockey probe ultrasound. High resolution ultrasound provided accurate information for the measurement of buccal bone thickness and lesion width and height.

Evaluation of the visibility of peri-implant bone defects using ultrasonography with two types of probes

Background: The aim of the present study was to evaluate the efficacy of intraoral and extraoral ultrasonography evaluations performed with two different types of probes (linear and “hockey stick”) for the visibility of peri-implant bone defects. Material and methods: Fourteen implants were inserted into sheep heads. Peri-implant bone defects were created without knowing the depth, which served as the gold standard for the defects. The defects were scanned with two different probe types (linear and hockey stick probes) extraorally and intraorally, using two different ultrasonography systems. For intra- and interobserver agreements for each probe types, Kappa coefficients were calculated. Results: The lowest ICC values were found in both intra- (ICC = 0.696) and interobserver reliability (ICC = 0.762) obtained with the extraorally used linear probe. There was a high agreement with the gold standard when using hockey sticky probes intraorally. For both linear probes, there were no significant differences in agreement among the two observers and the gold standard (p >0.05). Conclusions: High agreement was found when using high-frequency hockey stick probes intraorally, which means that they can be used with good effect for the evaluation of the visibility of peri-implant bone defects. To the best of our knowledge, this study is the first one on this subject. Thus, it can be stated that US can be an alternative method of examining defects. However, further studies are needed to evaluate the effectiveness of US in visualizing peri-implant bone defects.

The Chairside Periodontal Diagnostic Toolkit: Past, Present, and Future

Periodontal diseases comprise a group of globally prevalent, chronic oral inflammatory conditions caused by microbial dysbiosis and the host immune response. These diseases specifically affect the tooth-supporting tissues (i.e., the periodontium) but are also known to contribute to systemic inflammation. If left untreated, periodontal diseases can ultimately progress to tooth loss, lead to compromised oral function, and negatively impact the overall quality of life. Therefore, it is important for the clinician to accurately diagnose these diseases both early and accurately chairside. Currently, the staging and grading of periodontal diseases are based on recording medical and dental histories, thorough oral examination, and multiple clinical and radiographic analyses of the periodontium. There have been numerous attempts to improve, automate, and digitize the collection of this information with varied success. Recent studies focused on the subgingival microbiome and the host immune response suggest there is an untapped potential for non-invasive oral sampling to assist clinicians in the chairside diagnosis and, potentially, prognosis. Here, we review the available toolkit available for diagnosing periodontal diseases, discuss commercially available options, and highlight the need for collaborative research initiatives and state-of-the-art technology development across disciplines to overcome the challenges of rapid periodontal disease diagnosis.

Ultrasonography for chairside evaluation of periodontal structures: A pilot study

BACKGROUND

The crestal bone level and soft tissue dimension are essential for periodontal diagnosis and phenotype determination; yet, existing measurement methods have limitations. The aim of this clinical study was to evaluate the correlation and accuracy of ultrasound in measuring periodontal dimensions, compared to direct clinical and cone-beam computed tomography (CBCT) methods.

METHODS

A 24-MHz ultrasound probe prototype, specifically designed for intraoral use, was employed. Periodontal soft tissue dimensions and crestal bone levels were measured at 40 teeth and 20 single missing tooth gaps from 20 patients scheduled to receive a dental implant surgery. The ultrasound images were interpreted by two calibrated examiners. Inter-rater agreement was calculated by using inter-rater correlation coefficient (ICC). Ultrasound readings were compared with direct clinical and CBCT readings by using ICC and Bland-Altman analysis.

RESULTS

The following six parameters were measured: 1) interdental papilla height (tooth), 2) mid-facial soft tissue height (tooth), 3) mucosal thickness (tooth), 4) soft tissue height (edentulous ridge), 5) mucosal thickness (edentulous ridge), and 6) crestal bone level (tooth). Intra-examiner calibrations were exercised to achieve an agreement of at least 0.8. ICC between the two readers ranged from 0.482 to 0.881. ICC between ultrasound and direct readings ranged from 0.667 to 0.957. The mean difference in mucosal thickness (tooth) between the ultrasound and direct readings was -0.015 mm (95% CI: -0.655 to 0.624 mm) without statistical significance. ICC between ultrasound and CBCT ranged from 0.654 to 0.849 among the measured parameters. The mean differences between ultrasound and CBCT range from -0.213 to 0.455 mm, without statistical significance.

CONCLUSION

Ultrasonic imaging can be valuable for accurate and real-time periodontal diagnosis without concerns about ionizing radiation.

Periodontal evaluation using a non-invasive imaging method (ultrasonography)

The periodontal disease and gingival bleeding are highly prevalent in the adult population worldwide. The World Health Organization (WHO) data shows that 90–100% of the 34-year-old adults present gingival inflammation. Therefore, an investigation method is required to allow the assessment of the periodontal disease as well as the monitoring of the evolution of the gingival inflammation after periodontal treatments. Non-invasive and operator-independent methods for periodontal examination are necessary for diagnosing and monitoring the periodontal disease. The periodontal ultrasonography is a reliable technique for visualizing the anatomical elements which are necessary to diagnose the periodontal status. Using this imaging technique the dentino-enamel junction, the cortical bone, the radicular surface from the crown to the alveolar bone, the gingival tissue can be seen without interfering with those elements during the examination. Also, calculus visualization is possible before and after scaling in order to evaluate the quality of the treatment.

Using 2D ultrasonography is not feasible in dental practice as it requires extensive experience and is also time consuming. The reproducibility of the 2D slices is very difficult in order to have the possibility to compare different investigations efficiently. 3D reconstructions of the periodontal tissue can be a very good alternative to eliminate the operator dependence.

Ultrasonography allows the practitioner to visualize the anatomic elements involved in making a periodontal diagnosis. It also allows tracking of subsequent changes. This method is not commonly used for periodontal examination and further studies are required. Previous studies show that ultrasonography can be a reliable non-invasive method to diagnose and monitor the periodontal disease.

Assessment of Buccal Bone Surrounding Dental Implants Using a High-Frequency Ultrasound Scanner

The purpose of this study was to determine the buccal bone dimensions surrounding dental implants using a high-frequency ultrasound (US) scanner and cone-beam computed tomography (CBCT). Dental implants (n = 10) inserted in the maxilla of dry skulls were scanned using US (28 MHz, bandwidth 84%, aperture 6 mm, focal depth 13.2 mm) and CBCT (70 kV, 6.3 mA, voxel size 0.18 mm). The bone level and buccal bone thickness were determined on the buccal-lingual diameter of the implant. As a control group, the evaluated site was represented by a stone block containing the dental implant, and measurements were performed using an optical microscope. Statistical analysis was performed using a mixed linear regression model at a significance level of p < 0.05. There was no statistical difference among groups for the two measurements. For ultrasound, the mean discrepancy was 0.38 mm for bone thickness and 0.68 mm for bone level. For CBCT, the mean discrepancy was 0.51 mm for bone thickness and 0.09 mm for bone level. High-frequency ultrasound was able to measure buccal bone dimensions surrounding dental implants.

Accuracy of High-Frequency Ultrasound Scanner in Detecting Peri-implant Bone Defects

The purpose of this study was to assess the accuracy of high-frequency ultrasound (US) in the measurement of peri-implant bone defects in comparison with cone-beam computed tomography (CBCT) and micro-computed tomography (µCT). Bone defects were mechanically created around dental implants inserted into porcine ribs (n = 10). The bone samples were scanned by CBCT, µCT and US. Linear dimensions of the peri-implant defects were determined for supra-alveolar component, intra-bony component and width. The accuracy of measurements was evaluated with repeated-measures analysis of variance and the intra-class correlation coefficient at p ≤ 0.05. US underestimated the measurements for the supra-alveolar and intra-bony components in comparison to CBCT and µCT, and there were no statistically significant differences in the measurements of width. The intra-class correlation coefficient of US ranged from 0.96 to 0.98, whereas that for CBCT ranged from 0.77 to 0.97. US was accurate in measuring the width of peri-implant defects, although vertical measurements were underestimated by approximately 1 mm in comparison to those of CBCT and µCT.

Ultrasound in Dentistry: Toward a Future of Radiation-Free Imaging

Ultrasonography (US) is a noninvasive, nonionizing, inexpensive, and painless imaging tool proven to be a valuable diagnostic tool in soft tissue assessment that also shows promise for hard tissue evaluation in dentistry. US has been investigated for its capability to identify carious lesions, tooth fractures or cracks, periodontal bony defects, maxillofacial fractures, and more. It has been used as a diagnostic aid in temporomandibular disorders, implant dentistry, and to measure muscle and soft tissue thickness. Unfortunately, the use of US in dentistry is still in its infancy; however, relevant research is promising.

QUANTITATIVE ASSESSMENT OF GINGIVAL INFLAMMATION USING HIGH-RESOLUTION ULTRASOUNDEX-VIVO

This study investigates the feasibility of using high-resolution ultrasound imaging echogenicity to quantitatively diagnose gingival inflammation. Gingival samples were extracted from the study participants during gingivectomy procedures. Ultrasound mechanical scanning of the samples was immediately conducted ex-vivo to render cross-sectional images of high resolution, at different locations. Samples’ histological preparation and analysis was followed after performing ultrasound imaging. Histological sections were then matched with ultrasound images at different sections for each gingival sample. The matched image pairs were used to estimate two quantitative measures; relative inflammation area and ultrasound image echogenicity. These parameters were employed to judge the diagnostic potential of gingival ultrasound imaging. The results show that ultrasound images exhibited low intensity levels at the inflamed gingival regions, while healthy layers showed higher intensity levels. The relative area parameter implied a strong relationship between ultrasound and histological images. Ultrasound echogenicity was found to be statistically significant in differentiating between some inflammation degrees in the studied gingival samples. In summary, ultrasound imaging has the potential to be a noninvasive adjunct diagnostic tool for gingival inflammation, and may help assess the stage of the disease and ultimately limit periodontal disease occurrence; taking into consideration the limits of this study.

Integration of ultrasound imaging into pre-clinical dental education

INTRODUCTION

Patients have complex healthcare needs and typically require more than one healthcare discipline to address issues regarding their health. Interprofessional teams of healthcare professionals may be able to address these complex needs and improve patient outcomes by combining resources. To evaluate the feasibility of integrating ultrasound into a dental school curriculum to teach anatomy as part of an interprofessional education experience, the current study surveyed first-year dental students to determine their perceptions of the integration of ultrasound techniques into the curriculum.

MATERIALS AND METHODS

Ultrasound laboratory exercises were developed for first-year dental students as part of their anatomy course. The exercises were focused on head, neck and abdominal anatomy. To assess student perception of the integration of ultrasound into the dental curriculum, a survey was created specifically for the current study.

RESULTS

Between 2013 and 2015, two classes of first-year dental students participated in the ultrasound laboratory exercise and completed the survey (n = 83). Student survey responses suggested ultrasound was a valuable teaching tool because it allowed them to visualise anatomical structures using live imaging. They also agreed that the ultrasound laboratory exercises were an efficient learning tool, but the majority did not believe that they would use ultrasound regularly in their future practice.

CONCLUSIONS

Results of the current study suggested first-year dental students were satisfied with the integration of ultrasound techniques into the dental curriculum. Survey results indicated that the students enjoyed the ultrasound laboratory exercise and felt ultrasound was an effective learning tool.

Ultrasonographically locating the mental foramen and its soft tissue relations

OBJECTIVES

This ultrasound-based cross-sectional study aimed to visualize, locate and compare the position of the mental foramen with regard to its relationship to various soft tissue landmarks.

METHODS

100 Black and Caucasian subjects were included. An ultrasound transducer was used to locate the mental foramina. Distances to various landmarks were measured and compared.

RESULTS

All mental foramina were visualized. The mean soft tissue distance of the entire group from the mental foramen on the right and left sides, respectively, were as follows: (a) 3.4 mm [standard deviation (SD) 1.7 mm] and 3.4 mm (SD 1.5 mm) lateral to a vertical line passing through the chelion; (b) 20.1 mm (SD 2.6 mm) and 20.1 mm (SD 2.6 mm) distal to a horizontal line bisecting the chelions; (c) 15.1 mm (SD 2.4 mm) and 15.0 mm (SD 2.4 mm) proximal to the inferior border of the mandible. We found no statistically significant differences between race groups, between gender group and between age categories with regard to the horizontal soft tissue distance from a vertical line passing through the chelion to the mental foramen on the right or left sides. There were statistically significant (but not clinically significant) differences between race groups and between gender groups but not between age groups with regard to the vertical soft tissue distance from a horizontal line bisecting the chelions to the mental foramen as well as from the inferior border of the mandible to the mental foramen on both the right and left sides.

CONCLUSIONS

This study suggests that ultrasound is a feasible imaging modality that can be utilized to locate the mental foramen. Differences in the position of the mental foramen with regard to various soft tissue landmarks are minor and clinically insignificant.

Assessment of cortical bone thickness using ultrasound

PURPOSE

The aim of the study was to analyze the accuracy of measuring the cortical bone thickness using a combination of low- and high-frequency ultrasound (US) compared with cone-beam computed tomography (CBCT) and using stereomicroscopy as reference method.

MATERIAL AND METHODS

Ten jawbone models were prepared using bovine ribs and porcine gingiva. A dental implant was placed in each model. All models were investigated by US, CBCT, and stereomicroscopy. The cortical bone thickness was measured directly above and 4 mm beside the implant with each method in different slices.

RESULTS

The median deviation of US measurements compared to the reference method was 0.23 mm. The CBCT method was slightly more accurate (median percent deviation of 9.2%) than the US method (10.3%). However, US measurements directly above the implant were more accurate than CBCT measurements with a median percent deviation of 10.5% for US vs. 11.8% for CBCT.

CONCLUSION

Ultrasound showed a high potential to supplement CBCT for measurements of the cortical bone thickness.

Non-ionizing real-time ultrasonography in implant and oral surgery: A feasibility study

PURPOSE

Ultrasound imaging has potential to complement radiographic imaging modalities in implant and oral surgery given that it is non-ionizing and provides instantaneous images of anatomical structures. For application in oral and dental imaging, its qualities are dependent on its ability to accurately capture these complex structures. Therefore, the aim of this feasibility study was to investigate ultrasound to image soft tissue, hard tissue surface topography and specific vital structures.

MATERIAL AND METHODS

A clinical ultrasound scanner, paired with two 14-MHz transducers of different sizes (one for extraoral and the other for intraoral scans), was used to scan the following structures on a fresh cadaver: (i) the facial bone surface and soft tissue of maxillary anterior teeth, (ii) the greater palatine foramen; (iii) the mental foramen and (iv) the lingual nerve. Multiple measurements relevant to these structures were made on the ultrasound images and compared to those on cone-beam computed tomography (CBCT) scans and/or direct measurements.

RESULTS

Ultrasound imaging could delineate hard tissue surfaces, including enamel, root dentin and bone as well as soft tissue with high resolution (110 μm wavelength). The greater palatine foramen, mental foramen and lingual nerve were clearly shown in ultrasound images. Merging ultrasound and CBCT images demonstrated overall spatial accuracy of ultrasound images, which was corroborated by data gathered from direct measurements.

CONCLUSION

For the first time, this study provides proof-of-concept evidence that ultrasound can be a real-time and non-invasive alternative for the evaluation of oral and dental anatomical structures relevant for implant and oral surgery.

Numerical Analysis of Dental Caries Effect on the Biomechanical Behavior of the Periodontal System

The aim of this study was to investigate the effect of dental caries on the stability of the periodontal system. This study presents a numerical analysis performed with three-dimensional (3D) finite element (FE) method to evaluate stresses in the bone surrounding the tooth with dynamic mastication combined loadings. In this work, we present a comparative study on infected and healthy periodontal systems. The infected tooth was modeled and a caries defect was introduced to the tooth coronal part. The infected tooth was evaluated and equivalent von Mises interface stress values were obtained for comparison with the ones exhibited by the healthy tooth. Our results by 3D FE analysis indicated that maximum stresses occurred primarily at the cervical level of root and alveolar bone. In the cortical bone, the stress value was greater in infected system (21.641 MPa) than in healthy system (15.752 MPa), i.e., a 37.4% increase. However, in the trabecular bone we observed only 1.6% increase in the equivalent stress values for the infected tooth model. Stress concentration at the cervical level may cause abnormal bone remodeling or bone loss, resulting loss of tooth attachment or bone damage. Our findings showed that decayed single-rooted teeth are more vulnerable to apical root resorption than healthy teeth. The numerical method presented in this study not only can aid the elucidation of the biomechanics of teeth infected by caries but also can be implemented to investigate the effectiveness of new advanced restorative materials and protocols.

Effect of Cortical Bone Thickness on Detection of Intraosseous Lesions by Ultrasonography

Background. Usefulness of ultrasound (US) in detection of intrabony lesions has been showed. A cortical bone perforation or a very thin and intact cortical bone is prerequisite for this purpose. Objective. The current in vitro study was aimed at measuring the cut-off thickness of the overlying cortical bone which allows ultrasonic assessment of bony defects. Materials and Methods. 20 bovine scapula blocks were obtained. Samples were numbered from 1 to 20. In each sample, 5 artificial lesions were made. The lesions were made in order to increase the overlying bone thickness, from 0.1 mm in the first sample to 2 mm in the last one (with 0.1 mm interval). After that, the samples underwent ultrasound examinations by two practicing radiologists. Results. All five lesions in samples numbered 1 to 11 were detected as hypoechoic area. Cortical bone thickness more than 1.1 mm resulted in a failure in the detection of central lesions. Conclusion. We can conclude that neither bony perforation nor very thin cortical bones are needed to consider US to be an effective imaging technique in the evaluation of bony lesion.

Recent advances in imaging technologies in dentistry

Dentistry has witnessed tremendous advances in all its branches over the past three decades. With these advances, the need for more precise diagnostic tools, specially imaging methods, have become mandatory. From the simple intra-oral periapical X-rays, advanced imaging techniques like computed tomography, cone beam computed tomography, magnetic resonance imaging and ultrasound have also found place in modern dentistry. Changing from analogue to digital radiography has not only made the process simpler and faster but also made image storage, manipulation (brightness/contrast, image cropping, etc.) and retrieval easier. The three-dimensional imaging has made the complex cranio-facial structures more accessible for examination and early and accurate diagnosis of deep seated lesions. This paper is to review current advances in imaging technology and their uses in different disciplines of dentistry.

Recent advances of ultrasound imaging in dentistry--a review of the literature

Ultrasonography as an imaging modality in dentistry has been extensively explored in recent years due to several advantages that diagnostic ultrasound provides. It is a non-invasive, inexpensive, painless method and unlike X-ray, it does not cause harmful ionizing radiation. Ultrasound has a promising future as a diagnostic imaging tool in all specialties in dentistry, for both hard and soft tissue detection. The aim of this review is to provide the scientific community and clinicians with an overview of the most recent advances of ultrasound imaging in dentistry. The use of ultrasound is described and discussed in the fields of dental scanning, caries detection, dental fractures, soft tissue and periapical lesions, maxillofacial fractures, periodontal bony defects, gingival and muscle thickness, temporomandibular disorders, and implant dentistry.

Visibility of dental pulp spaces in dental ultrasound

The purpose of this study was to assess the feasibility of dental ultrasound with conventional sonographic equipment. The teeth of three adult volunteers who had cone beam CT examinations performed previously with clinical indications and one extracted tooth were examined using linear and compact (hockey stick) sonographic probes. The sonographic images were compared with cone beam CT images reconstructed accordingly. Dental pulp spaces were demonstrated in all teeth not covered with prosthetic crowns. The dentin and pulp were best visualized at the level of the neck of the teeth. The dentin was hypoechoic, and the superficial layer comprising the cementum and the pulp spaces were hyperechoic. Dental ultrasound is feasible with general purpose sonographic machines. The buccal surfaces of all teeth are accessible with a compact (hockey stick) probe. Visualization and differentiation of dental pulp spaces, dentin and the superficial layer comprising cementum is possible in the portions of teeth not covered by the alveolar bone or prosthetic crowns. The dental pulp spaces are best seen at the level of the tooth neck. Pulp and endodontic fillings can be distinguished on ultrasound.

Intraoral ultrasonography: development of a specific high-frequency probe and clinical pilot study

Although ultrasonography is a non-invasive, inexpensive and painless diagnostic tool for soft tissue imaging, this technique is not currently used for oral exploration. Therefore, we developed a 25-MHz high-frequency ultrasound probe, specially designed for intraoral applications. This paper aims to present clinical intraoral ultrasound images actually interpretable, in order to identify the relevant applications of this novel tool and to design future oral studies. Two independent radiologists performed ultrasound examinations on three healthy volunteers. All the teeth were explored on the lingual and buccal sides (162 samples) to evaluate the ergonomics of the system and the visualisation of anatomic structures. Osseointegrated dental implants and a mucocele were also scanned. At the gingivodental junction of the maxillary and mandibular teeth, the device clearly identifies the tooth surfaces, the alveolar bone reflection with its surrounding subepithelial connective tissue of the gingiva and the gingival epithelia. The bone level and the thickness of soft tissue around the implant are measurable on the buccal and lingual sides. Therefore, intraoral ultrasonography provides additional morphological information that is not accessible by conventional dental x-rays. We propose a novel diagnostic tool that explores the biological width and is able to define the thin or thick nature of the gums. Moreover, intraoral ultrasonography may help to monitor precancerous lesions. This promising device requires large-scale clinical studies to determine whether it should remain a research tool or be used as a diagnostic tool for daily dental practice.