Tooth decay (IMAGE) Indiana University School of Medicine Caption The dark stained decay is irreversible loss of tooth tissue that must be repaired with dental treatment. The white patch on the tooth is an earlier stage of decay which can be stopped without drilling and filling. Credit Andréa Ferreira Zandoná, DDS, PhD, Indiana University School of Dentistry Usage Restrictions Photo credit to Andréa Ferreira Zandoná, DDS, PhD, Indiana University School of Dentistry License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.