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The intimate relationship between the mandibular canal (MC) and the first mandibular molar tooth presents challenges when performing dentoalveolar surgical procedures due to the probability of causing iatrogenic injury to the inferior alveolar neurovascular bundle. Superimposition between the MC and the first molar (M1) tooth roots is often observed on intraoral dental radiographs in small breed dogs. However, due to the radiograph's bidimensional nature, it is impossible to determine the buccal or lingual localization of the first molar roots with respect to the MC. Thus, this study's objective was to determine the localization of the first molar tooth's roots in relation to the position of the MC and their overlapping percentage with the canal in small-bodyweight dogs (<15 kg) using tomographic diagnostic images. For this, cone-beam computed tomography and high-definition computed tomography exams from 103 small breed dogs (under 15 kg) were retrospectively assessed to determine the lingual or buccal localization of the first molar tooth's roots with respect to the MC and the degree of overlap of the roots with the canal. In conclusion, most of the roots of M1 of dogs under 15 kg were located at the MC's lingual aspect (82.7%) with an overall superimposition median with the MC of 100 and 90% for the mesial and distal roots, respectively. Straddle tooth roots were not a common anatomical presentation in the dogs of this study.

Internet-based recruitment can be effective in reaching large numbers of geographically diverse individuals. Geosocial sexual networking apps on smartphones have emerged as the modal way in which men who have sex with men (MSM) meet sex partners, and as venues for sexual health research. We report on the performance of three types of ads—text-only, text with male figure (no face), and text with male figure (with face)—used on a geosocial sexual networking app to advertise free at-home HIV testing and to enroll in an online study. We ran five 2-week-long ads on a popular MSM geosocial app between fall 2017 and spring 2018 (~2.19 million impressions). Ads were evaluated in terms of the click-through rate (CTR = advertisement clicks/advertisement impressions), conversion rates (CR = number of enrolled participants/ad-generated clicks), cost per enrolled participant, and demographic composition of survey respondents. We enrolled n = 4,023 individuals, n = 2,430 of whom completed HIV testing—$6.21 spent on advertising per participant enrolled and $10.29 spent for everyone who completed HIV testing. Cost per enrolled participant was associated with the content of the ad used—ads featuring male figures (with or without a face shown) were more cost efficient than ads featuring text alone. These ads also outperformed text-only ads across a range of metrics, including responsiveness among younger MSM as well as MSM of color. Advertising materials that combine text with images may have greater appeal among priority populations.