This study assessed the reliability of smartphone images of plaque-disclosed anterior teeth for evaluating plaque scores among preschool children. Additionally, the reliability of plaque scores recorded from smartphone images of anterior teeth in representing the overall clinical plaque score was also assessed. Fifteen preschool children were recruited for this pilot study. The Simplified Debris Index (DI-S), the debris component of the Simplified Oral Hygiene Index, was used to record the plaque score. A plaque-disclosing tablet was used to disclose the plaque before the plaque score recording. Following that, the image of the anterior teeth (canine to canine) of both the upper and lower arch was captured using the smartphone. Each child had three different DI-S recorded. For the first recording of the overall clinical DI-S, the plaque score was recorded clinically from index teeth 55 (buccal), 51 (labial), 65 (buccal), 71 (labial), 75 (lingual) and 85 (lingual). For the second recording, anterior clinical DI-S, the plaque score was recorded clinically from the labial surfaces of six anterior teeth only (53, 51, 63, 73, 71 and 83). Two weeks later, anterior photographic DI-S (third recording) was done using the smartphone images of the same index teeth used for the second recording. The intra-class correlation coefficient (ICC) was calculated to evaluate the reliability of smartphone images in assessing plaque scores. The results showed high reliability (ICC = 0.987) between anterior clinical and anterior photographic examinations, indicating that smartphone images are highly reliable for evaluating plaque scores. Similarly, high reliability (ICC = 0.981) was also found for comparison between overall clinical DI-S and anterior photographic DI-S, indicating plaque scores recorded from smartphone images of anterior teeth alone can represent the overall clinical plaque score. This study suggests that smartphone images can be a valuable tool for remote screening and monitoring of oral hygiene in preschool children, contributing to better oral health outcomes.