The generative potential of mess in community-based participatory research with young people who use(d) drugs in Vancouver.

Community-based participatory research (CBPR) is increasingly standard practice for critical qualitative health research with young people who use(d) drugs in Vancouver, Canada. One aim of CBPR in this context is to redress the essentialization, erasure, and exploitation of people who use(d) drugs in health research. In this paper, we reflect on a partnership that began in 2018 between three university researchers and roughly ten young people (ages 17-28) who have current or past experience with drug use and homelessness in Greater Vancouver. We focus on moments when our guiding principles of shared leadership, safety, and inclusion became fraught in practice, forcing us in some cases to re-imagine these principles, and in others to accept that certain ethical dilemmas in research can never be fully resolved. We argue that this messiness can be traced to the complex and diverse positionalities of each person on our team, including young people. As such, creating space for mess was ethically necessary and empirically valuable for our CBPR project.

Non-destructive clinical assessment of occlusal caries lesions using near-IR imaging methods.

OBJECTIVE: Enamel is highly transparent in the near-IR (NIR) at wavelengths near 1,300 nm, and stains are not visible. The purpose of this study was to use NIR transillumination and optical coherence tomography (OCT) to estimate the severity of caries lesions on occlusal surfaces both in vivo and on extracted teeth. METHODS: Extracted molars with suspected occlusal lesions were examined with OCT and polarization sensitive OCT (PS-OCT), and subsequently sectioned and examined with polarized light microscopy (PLM) and transverse microradiography (TMR). Teeth in test subjects with occlusal caries lesions that were not cavitated or visible on radiographs were examined using NIR transillumination at 1,310 nm using a custom built probe attached to an indium gallium arsenide (InGaAs) camera and a linear OCT scanner. After imaging, cavities were prepared using dye staining to guide caries removal and physical impressions of the cavities were taken. RESULTS: The lesion severity determined from OCT and PS-OCT scans in vitro correlated with the depth determined using PLM and TMR. Occlusal caries lesions appeared in NIR images with high contrast in vivo. OCT scans showed that most of the lesions penetrated to dentin and spread laterally below the sound enamel. CONCLUSION: This study demonstrates that both NIR transillumination and OCT are promising new methods for the clinical diagnosis of occlusal caries.

Imaging Natural Occlusal Caries Lesions with Optical Coherence Tomography.

Several studies have demonstrated that polarization-sensitive optical coherence tomography (PS-OCT) can be used to nondestructively measure the severity of demineralization in the important occlusal surfaces. The purpose of this study was to assess the potential of PS-OCT and OCT methods for the measurement of the depth of natural occlusal carious lesions. Teeth were screened for potential occlusal lesions using near infrared imaging (NIR). A PS-OCT system operating at 1310-nm was used to acquire polarization resolved images of the area of interest on the occlusal surface. The teeth were serial sectioned to 200 µm thickness and examined with polarized light microscopy (PLM) and Transverse Microradiography (TMR) for comparison. The lesion depth measured nondestructively with PS-OCT was compared to the lesion depth measured with PLM and TMR to assess the performance of these methods and determine if polarization sensitivity is required. The lesion depth measured using OCT correlated well with the lesion depths measured with TMR and PLM. Although polarization sensitivity provided better contrast it was not necessary to have polarization sensitivity to identify deep occlusal lesions.