To evaluate the effects of using an intra-oral camera (IOC) during supportive periodontal therapy (SPT), on the psychological, behavioral, and clinical parameters of patients with gingivitis, outlined by evidence and a theory-based framework. A group of 78 adult patients with gingivitis receiving an SPT was randomized into two groups: IOC and control. Bleeding on Marginal Probing (BOMP), self-reported dental hygiene behaviors, and psychological determinants of behavior change (outcome expectancies, self-efficacy, and planning) and IOC opinion were evaluated 1 week before or during the appointment and 4 months later. Repeated-measures anova was used to compare groups over time. Almost all the patients brushed their teeth daily, while 78% either never or hardly ever used dental floss. The IOC group showed significant improvements in BOMP index (P < 0.001), self-reported flossing (P < 0.05), and self-efficacy (P < 0.05) compared to the control group. The use of IOC significantly improves clinical, behavioral, and psychological determinants of periodontal health 4 months after treatment.