Imaging Tooth-Periodontium Complex Using Ionizing Radiation-Free Ultrasound
Creators: Nguyen, Kim Cuong
Publisher: name: University of Alberta Library
Year: 2023

<p>Crowding and misalignment of teeth, known as malocclusion, can cause patients oral functioning problems such as jaw movement, chewing, speech, and high sensitivity to periodontal diseases. Correction of the malocclusion requires orthodontic treatment. Cone-beam computed tomography (CBCT) has been routinely used in orthodontic diagnosis and treatment planning but delivers more hazardous ionizing radiation than conventional dental X-ray. This dissertation was devoted to developing ultrasound (US) imaging as an innovative, ionizing radiation-free, less costly, and non-invasive clinical diagnostic tool for dentistry.<br>
US imaging is innovative for visualizing periodontium and measuring clinical parameters. A literature search of publications that reported the use of ultrasonography for periodontium was needed. In addition, the comparison between US and CBCT in dental imaging was also included in the search. In this study, a comprehensive systematic review was conducted to examine the US accuracy and reliability in evaluating the alveolar bone level.<br>
Imaging small features of the periodontium requires a high-resolution and high-frequency US. A commercial high-frequency (20 MHz) US transducer was used and was able to provide high-resolution visualization of the periodontium. As a result, US delivered reliable measurements of alveolar bone level compared to CBCT in a study on adolescents.<br>
In addition, since US is an emerging imaging modality and new to dental practitioners, image interpretation is difficult for them and a current obstacle hindering practice in clinics. This dissertation has delivered proof that machine learning methods can reliability conduct the alveolar bone segmentation and cementum-enamel junction and alveolar bone crest localization against ground truth identified by clinicians.<br>
Moreover, US imaging technology utilizes ultrasonic gels to facilitate wave energy transmission during scanning. Typical medical gels are in the form of liquids and are not meant for intraoral usage. This research has shown that hydrogels, which have low cytotoxicity, improved mechanical properties than liquid gels, are stable in water-soaking, have low attenuation, and have similar acoustic impedance to water, can be used in intraoral US.<br>
Furthermore, this research has shown strong evidence that higher frequency results in better image quality of periodontium visualization. A study was conducted to investigate the optimal frequency for intraoral US imaging. US with centre frequencies from 15 MHz to 50 MHz was evaluated for accuracy and reliability compared to the current standards, i.e., μCT (micro-computed tomography) and CBCT. It was observed that high frequencies above 20 MHz yielded satisfactory image quality and provided clinically acceptable accuracy and reliability; especially, 30 MHz US demonstrated optimal results in both image quality and evaluation of alveolar bone (AB).<br>
In summary, my Ph.D. research has developed US technologies and evaluated how US can be used as a diagnostic tool for imaging periodontium. US imaging has demonstrated clinically acceptable accuracy and reliabilities compared to the standards, i.e., μCT and CBCT. Moreover, US possesses many advantages of non-ionizing radiation, non-invasive technique, acceptance by most patients, low-cost process, and machine learning-based interpretation.</p>