[Fundamental and practical study for DNA analysis using tooth as a source of DNA].
Degree of degradation and the yield of DNA extracted from dental pulp tissues were examined on the tooth samples (n = 50) stored at room temperature and the method of DNA extraction from tooth hard tissues was also investigated. The DNA samples obtained were also applied to forensic odontological material examination including DNA fingerprinting using a probe Myo and VNTR (variable number of tandem repeat) analysis in D4S43 locus by PCR. The amount of DNA obtained from the dental pulp tissue of a single tooth varied approximately from 3 to 40 micrograms. In most cases, high molecular weight DNA was still present in samples stored at room temperature for at least 336 days. When the dental pulp tissue samples were less than 5 mg in weight, the amount DNA extracted was usually less than 10 micrograms, however when the samples were more than 5 mg in weight, the amount of DNA extracted was more than 10 micrograms. No correlation was observed between the storage period of the tooth samples and the DNA extraction ratio (the amount of extracted DNA weight, micrograms/pulp weight, mg). The efficiency of DNA extraction from tooth hard tissues was investigated under different conditions using 0.005 M and 0.5 M EDTA solutions for decalcification. DNA was efficiently extracted from the tooth samples which were decalcified for one week without changing the 0.5 M EDTA solution or by changing the solution once within a week. Rapid decalcification using formic acid buffer was not suitable for DNA extraction from tooth hard tissues. Southern blot hybridization of DNA samples extracted from pulp tissues using Myo probe gave multiple bands. Finger print patterns obtained from DNA recovered from dental pulp and tooth hard tissues samples were identical, however, the number of hybridizing bands obtained from tooth hard tissues was less than that obtained from blood and dental pulp tissues. The D4S43 typing using DNA recovered from blood stains, dental pulp tissues and tooth hard tissues of the same individuals was in agreement with each other and the 184bp fragment was efficiently amplified in all the samples tested. The DNA obtained from dental pulp tissues usually contains high molecular weight DNA and was suitable for multilocus probe and PCR analysis. However, the DNA obtained from tooth hard tissues was suitable only for PCR analysis.