<prompt> The most reliable criteria in Gustafsons method of age estimation is:AttritionSecondary dentin depositionTransparency of rootCementum apposition  <response>: Transparency of root is the most reliable among Gustafsons method of age estimation. It is not seen until about 30 years of age. The canals in the dentin are at first wide. With age they are filled by mineral, so that they become invisible and the dentin becomes transparent. Other criterias of Gustafsons method of age estimation: Attrition Paradentosis Secondary dentin Cementum apposition Root resorption Ref: Textbook of Forensic Medicine and Toxicology by K S Narayan Reddy, 27th edition, Page 63. 