Perbedaan pengetahuan orang tua dalam pemeliharaan kesehatan gigi dan mulut anak sebelum dan setelah pemberian media visual secara daring (Evaluasi di masa pandemi covid-19 melalui komunikasi, informasi, dan edukasi) = The difference of parental knowledge regarding children oral health care before and after displaying online visual media (Evaluation during covid-19 pandemic through communication, nformation, and education)