The identification of disease by careful investigation of patient¿s signs, symptoms and history, is often a matter of making choices in the face of uncertainty. Data gathering is the first step in the diagnostic process and the medical & dental history play an extremely important role in collection of data. Laboratory tests can be used to screen for disease in asymptomatic individuals to establish or exclude the presence of disease in symptomatic patients and to assist the practitioner in the management of patient. Laboratory studies are an extension of physical examination in which tissue, blood, urine or other specimens are obtained from patients & subjected to histological, bio-examination, microbiological or immunological examination.

I Dr.Dharmasanam Ramya, post graduate student in the specialty of Periodontics at Lenora Institute of Dental Sciences, Rajahmundry, Andhra Pradesh.