Lactobacilli characteristically cause existing carious lesions to progress, especially those in coronal caries. Preformed metal crowns are now recommended as the optimum restoration for managing carious primary molars. It is more common when gingivitis and carious teeth are present. This may include a carious lesion that has not reached the pulp. Most importantly, whether the carious lesion is cavitated or non-cavitated dictates the management.