ABSTRACT: BACKGROUND:Effective preventive treatments for dental decay exist, but caries experience among preschoolers has not changed, with marked disparities in untreated decay. Despite near-universal use of SMS text messaging, there are no studies using text messages to improve the oral health of vulnerable children. OBJECTIVE:This randomized controlled feasibility trial aimed to test the effects of oral health text messages (OHT) versus a control (child wellness text messages or CWT). OHT was hypothesized to outperform CWT on improving pediatric oral health behaviors and parent attitudes. METHODS:Parents with a child aged <7 years were recruited at urban clinics during pediatric appointments (79% [41/52] below poverty line; 66% [36/55] black) and randomized to OHT (text messages on brushing, dental visits, bottle and sippy cups, healthy eating and sugary beverages, and fluoride) or CWT (text messages on reading, safety, physical activity and development, secondhand smoke, and stress) groups. Automated text messages based on Social Cognitive Theory were sent twice each day for 8-weeks. Groups were equivalent on the basis of the number of text messages sent, personalization, interactivity, and opportunity to earn electronic badges and unlock animated characters. Assessments were conducted at baseline and 8 weeks later. Data were analyzed with linear mixed-effects models. RESULTS:A total of 55 participants were randomized (28 OHT and 27 CWT). Only one participant dropped out during the text message program and 47 (24 OHT and 23 CWT) completed follow up surveys. Response rates exceeded 68.78% (1040/1512) and overall program satisfaction was high (OHT mean 6.3; CWT mean 6.2; 1-7 scale range). Of the OHT group participants, 84% (21/25) would recommend the program to others. Overall program likeability scores were high (OHT mean 5.90; CWT mean 6.0; 1-7 scale range). Participants reported high perceived impact of the OHT program on brushing their child's teeth, motivation to address their child's oral health, and knowledge of their child's oral health needs (mean 4.7, 4.6, and 4.6, respectively; 1-5 scale range). At follow up, compared with CWT, OHT group participants were more likely to brush their children's teeth twice per day (odds ratio [OR] 1.37, 95% CI 0.28-6.50) and demonstrated improved attitudes regarding the use of fluoride (OR 3.82, 95% CI 0.9-16.8) and toward getting regular dental checkups for their child (OR 4.68, 95% CI 0.24-91.4). There were modest, but not significant, changes in motivation (F1,53=0.60; P=.45) and self-efficacy (F1,53=0.24; P=.63) to engage in oral health behaviors, favoring OHT (d=0.28 and d=0.16 for motivation and self-efficacy, respectively). CONCLUSIONS:The OHT program demonstrated feasibility was well utilized and appealing to the target population and showed promise for efficacy.