 Hello everyone welcome back to the continuation of our dental age estimation methods so last session we finished Damagen's method of radiographic dental age estimation today's session is about the morphological method that is a Gustavson method of dental age estimation. So X fiber means I told you we need to remove the tooth with minimal alteration under the examination to estimate the age so it is a morphological method so in 1950 Gustavson introduced this age estimation method based on the morphological and histological changes of the tooth so he has six criteria and based on this six criteria he planned the age estimation so the six stages are or the six criterias are the first one is the amount of occlusal attrition then the loss of periodontal attachment indicated by a indicated by p then the coronal secondary dentine deposition so it is secondary dentine denoted by s then the root resorption at the apex denoted by r then the dentine translucency denoted by t and the cementum apposition at the root apex so for each these regressive changes we formulated zero to three scores so we need to check the tooth for these changes for each change we need to score zero there is no change one with minimal change to moderate and serious change so if attrition we need to check the teeth if it is moderately attrated we going to put score two if the root resorption is moderate we are going to put two if the cementum at apex is more we are going to give three so likewise we are going to finally get a score okay that is score x so all these scores will be added and we get a score x okay and finally we get our age by a formula that is 11.43 plus 3.63 into x so this x is here we get by doing all these calculation okay so this is how we calculate Gustavson's method of age so you might be wondering where this 11.43 and 3.63 came from this is actually a regression equation it is a mathematical regression equation put forward by this Gustavson okay so it has finally reached to a standardized value this is a constant and this is a coefficient so you can put any x value and we will get a generalized population age so that is how this regression equation works so Gustavson's regression equation is this one 11.43 plus 3.63 into the x whereas the maples and rice character this formula maples and rice two scientists character this formula they change the constant value that is age is equal to 13.45 plus 4.26 into our x so suppose this x is 5 we are going to multiply 3.63 into 5 and add to this 11.43 okay so in this case it will be increased here both the values are more in place of 11.43 in maples and rice he said it is or it should be 13.45 and 4.26 into this 5 so we get any number of x in a particular it changes from person to person whereas Johnson Johnson has again modified this formula Johnson modified the formula like this before that he modified the scoring numbers that is 0 1 2 3 modified into 0 0.51 1.52 2.5 and 3 he added a 0.5 in between and he completely renovated this formula as 11.02 is a constant then each value will be added with coefficient that is 5.14 into the value of a 2.3 into the value of s 4.14 into the value of b then 3.17 to the value of c 5.57 into value of r and 8.98 into the value of t so finally we get the h so this is a mathematical regression equation first Gustavson modified 11.43 plus 3.63 into x then maples and rice 13.45 plus 4.26 into x but Johnson completely renovated that is 1.0 into all these each will be separately multiplying with the regressive changes so this is how we calculate Gustavson method so this method is basically directly we do examination morphological examination on the six criteria with a score of 0 1 2 3 and we get the score of x and we apply it on the equation so or Johnson's method whereas the first one what we studied is the divergence method it is a radiographical method we calculate it by various stages and converting into score and adding up the scores and comparing with the standardized table so that's all about two methods Gustavson and Imogen's method so next important topics in age estimation will be covered in future sessions hope you understood this method Gustavson and Imogen need to write all the content when writing for your exam okay so i'll come up with those sessions and then this GM mod thank you