1 Division of Pedodontics and Preventive Dentistry, Centre for Dental Education and Research, WHO Collaborating Centre for Oral Health Promotion, All India Institute of Medical Sciences, New Delhi, 110029, India. vijaymathur7@yahoo.com.
2 Department of Pedodontics and Preventive Dentistry, Sudha Rustogi Dental College, Faridabad, Haryana, India.