PCR (Polymerase chain reaction) - A revolution in forensic dentistry

More than 30 years ago, the introduction of recombinant DNA technology as a tool for the biological sciences revolutionized the study of life. Molecular cloning allowed the study of individual genes of living organisms; however this technique was dependent on obtaining a relatively large quantity of pure DNA. This depended on the replication of the DNA of plasmids or other vectors during cell division of microorganisms (1). Researchers found it extremely laborious and difficult to obtain a specific DNA in quantity from the mass of genes present in a biological sample (2). Recombinant DNA technology made possible the first molecular analysis and prenatal diagnosis of several human diseases. Fetal DNA obtained by amniocentesis sampling could be analyzed by restriction enzyme digestion, electrophoresis, southern transfer and hybridization to a cloned gene or oligonucleotide probes (3). However, southern blotting permitted only rudimentary mapping of genes in unrelated individual(4). PCR, an acronym for Polymerase Chain Reaction (5,6), allowed the production of large quantities of a specific DNA from a complex DNA template in a simple enzymatic reaction. PCR is a recently developed procedure for the in vitro amplification of DNA. PCR has transformed the way that almost all studies requiring the manipulation of DNA fragments may be performed as a results of its simplicity and usefulness(7).