Intraoral Ultrasound Imaging of Tooth-periodontium Complex

Overview

Misaligned teeth are very common in the population and are commonly known as malocclusion. This happens when the upper teeth do not align properly with the lower teeth. It can lead to difficulty in jaw movement, chewing, speech, and gum disease. Correction of malocclusion requires orthodontic (braces) treatment. Currently, the imaging technique known as cone-beam computed tomography (CBCT) has been routinely used in orthodontic diagnosis and treatment planning for patients with malocclusion. Although CBCT provides better information than conventional dental X-rays, it typically delivers more harmful radiation to the patients. This is especially important as radiation from repeated X-ray imaging during dental monitoring visits can be cumulative. Ultrasound is commonly used in medical imaging. The ultrasound method is non-invasive, cost-effective, and free of ionizing radiation. The application of ultrasound has been investigated in many fields in Dentistry. We plan to evaluate the ability of intra-oral ultrasound to see the bone and gingiva around the tooth for patients under orthodontic treatment. If ultrasound is found to be a reliable tool in imaging the tooth-gum complex, children and adolescents will benefit immensely from the decreased radiation risks and reduced cancer rate.

Purpose: The purpose of this study is to investigate a intraoral ultrasound to image the tooth-periodontium complex that is an alternative to ionizing radiation CBCT imaging. Hypothesis: Ultrasound imaging is a radiation-free alternative to image tooth-periodontium complex. Justification: Straight teeth and a healthy smile is paramount to an individual's well-being. Malocclusion (crowding of teeth) is the third most common dental anomaly according to the World Health Organization(WHO). The severity of malocclusion can cause difficulty in jaw movement, chewing, speech, and high susceptibility to gum disease. Correction of malocclusion problems requires comprehensive orthodontic treatment. CBCT imaging for orthodontic diagnosis and treatment planning has increased of late due to its inherent advantages over the traditional 2D planar cephalometric and panoramic radiography. These include the advantage of having 3D capabilities to view images with no superimposition or magnification errors. This is especially significant in detecting bony dehiscence and fenestration associated with orthodontic treatment. The presence of these defects decreases bony support to the teeth, which compounded with plaque-induced inflammation, can be detrimental to the health of the teeth during orthodontic tooth movement. CBCT image typically delivers much higher radiation than conventional dental radiographs. Orthodontic patients, mostly children, are increasingly susceptible to deleterious effects of ionizing radiation due to the accumulated radiation dose from repeated monitoring visits. Hence new imaging modalities such as ultrasound have been researched as a radiation-free alternative to CBCT imaging. The ultrasound technique uses echoes of mechanical waves and the acoustic properties of the target to produce an image non-invasively. The characteristics of the returning echoes are mainly governed by the elastic 'properties of the transmitting medium and the acoustic impedance contrast of the interface between the target and the surrounding medium. For decades, medical ultrasound has mainly been used to image soft tissues. Although the use of ultrasound in dentistry focused more on imaging dental hard tissues, most recently, its use has been expanded to image periodontal soft and hard structures. Although the interest in using ultrasound in dentistry is increasing, research on the use of ultrasound to study tooth-periodontal tissues is limited. Objectives: The objective of this study is to determine the validity and reliability of an intra-oral ultrasound technique in a clinical setting by comparing the ultrasound measurements with those of the clinical standard CBCT imaging. Research Method/Procedures: Participant recruitment: 60 orthodontic participants in the age group of 10-60 years old will be recruited for the study for over a year. This population group is screened and recruited from the patients seen at the Orthodontic Clinic in the Oral Health Clinic - Department of Dentistry based on the inclusion and exclusion criteria. Each subject will have diagnostic records taken as part of routine orthodontic diagnosis and treatment planning. These records include extraoral and intraoral photos, digital models, and CBCT imaging. In addition to routine diagnostic records, ultrasound scanning of the mandibular and maxillary incisor, canine, premolar, and molar teeth for a total of sixteen (16) teeth (four (4)teeth in each of the four quadrants) will be performed after obtaining informed consent from patients and their guardians. Following diagnostic records, all subjects will undergo orthodontic treatment for correction of their malocclusion by either a licensed orthodontic faculty member or an orthodontic resident under the supervision of a licensed orthodontist at Kaye Edmonton Dental Clinic, University of Alberta. Procedures: Ultrasound Scanning: The ultrasound scanner used is a handheld medical diagnostic system that has a Clarius platform (ClariusMobile Health, Richmond, Canada, Device ID: 1012444 and DeviceIdentifier 99-02-00046 ) and a DenSonics DSI-1 intraoral 20 MHz array transducer (DenSonics Imaging Inc, Edmonton, Canada) to be used off-label (Health Canada has not approved yet). All ultrasound scans will be done by the same research assistant after training. This research assistant has no involvement in the patient's care. The ultrasound imaging will be performed on the maxillary and mandibular(again 16 teeth per patient will be imaged - incisor/canine/premolar/molar in each of the four dental quadrants). The tooth-periodontium complex will be imaged. The probe will be isolated for infection control using a plastic wrap and will be positioned intraorally with a gel pad separating the ultrasound transducer and the targeted tooth-periodontium structures, with the long axis of the probe in alignment with the longitudinal axis of the tooth. On average, it takes about 1-2 minutes to perform a single scan, and we estimate a total of 25 minutes to perform scans on all the teeth in a single individual. The saved data will be exported to a desktop computer for data analysis and measurements using in-house developed MATLAB codes. Plan for Data Analysis: Outcome measures: The following five distance, thickness, or localization parameters will be measured linearly on ultrasound images for further analysis and comparison: (1) gingival margin- cementoenamel junction, (2) cementoenamel junction - alveolar bone crest, (3) gingival thickness at the alveolar bone crest, (4) alveolar bone thickness at the crest and (5) localization of cementoenamel junction. Measurements of the above five parameters will be performed by four raters in the ultrasound images. All the raters will be blinded for data processing and measurement. To test intra-rater reliability, each rater will conduct the measurement three times with one week apart between measurements to avoid bias. Three of the measurements: (2) cementoenamel junction - alveolar bone crest, (4) alveolar bone thickness at the crest and (5) localization of cementoenamel junction will be identified in both CBCT and ultrasound images and compared. Statistical analysis: Descriptive statistics will be presented as Mean±SD. Quality control of the data will be done by scatter plots to detect outliers. We will consider three assessments: Intra-rater reliability, inter-rater reliability, and agreement between the two methods. The intra- and inter-rater reliabilities will be assessed by intra-class correlation coefficients (ICC(2,1)) using a 2-way random model and absolute agreement with a 95% confidence interval. Correlation and the Bland-Altman plot will be used to assess the agreement between CBCT and ultrasound.