 Welcome back to a new session on dentistry and world. Today's topic is Ashley's analysis. So this analysis is peculiar because the tooth crowding, the analysis pointed to the arch width rather than arch length. So we have seen various analysis and one of them is Ashley House analysis and it stressing upon arch width not arch length. The tooth crowding is due to deficiency of arch width and not arch length. Most of the analysis we are seeing was due to the deficiency or discrepancy in the arch length. So Ashley House analysis stressing upon her relationship existing between the total width of mesiodisital diameter of teeth anterior to the second permanent molar that is mesiodisital diameter of teeth anterior to second molar that is first molar to first molar mesiodisital diameter and the width of dental arch in the first premolar region. The width of dental arch in the first premolar region. So this is a width of dental arch the first premolar region this is just diameter this is basal arch width. So it is is tricking the width of crown and root epises from first premolar to first premolar on left and right side. So the author pointing out there is a relationship which existing between the total width of mesiodisital diameter of teeth anterior to second permanent molar that is first molar to first molar and with the width of dendel arch between the first premolar to premolar that is between the first premolar region arch width and the total width of mesiodisital diameter. So in this analysis we have four parameters and the analysis is exclusively based on these four parameters. The first one is total tooth material. Total tooth material is nothing but the sum of mesiodisital width of the teeth from first molar to first molar. So that is the sum of mesiodisital width of first molar to first molar. Okay that is total tooth material. This is total tooth material and the second one is basal arch length. So this is basal arch length. So it is a perpendicular distance. It is a perpendicular distance from a tangent. So tangent is from the first permanent molar distal side. So this is a distal aspect. I just mentioned it as tooth number, central lateral canine, first premolar, second premolar and first molar. So the distal aspect of first molar we draw a tangent and draw a perpendicular to the anterior limit of arch. So that is basal arch length. It is a perpendicular distance from the tangent drawn from the distal aspect of first permanent molar. That is BAL or basal arch length. The third parameter is premolar diameter. So premolar diameter is arch width measured from the buccal cusp of first premolar on one side to the buccal cusp of first premolar on the other side. So that is buccal cusp of first premolar to the buccal cusp of first premolar on the left and right side. So that is the premolar diameter or PMD. So we are checking buccal cusp. So that is the arch diameter or premolar diameter. So the last one is PMBAW. There is nothing but premolar basal arch width. So here we were checking the buccal cusp from first premolar to first premolar on the left and right side. But this PMBAW we are checking the root epises of first premolar to first premolar. That is premolar basal arch width. This is buccal root cusp and this is root epises. So these are the four parameters of Ashley House analysis based upon the analysis of final results will be assessed. The total tooth material basal arch length premolar diameter premolar basal arch width. Now let us move on to the percentage calculation of premolar diameter to total tooth material. It is nothing but premolar diameter divided by total tooth material into 100. If it is PMBAW that is premolar basal arch width divided by total tooth material into 100 or basic arch length divided by total tooth material into 100. So all this percentage we can calculate and we commonly express the result or commonly say with the premolar basal arch width. Suppose the premolar basal arch width to total tooth material percentage is less than 37 percentage. So we should do extraction or it requires extraction so that particular patients cast after analysis after checking premolar basal arch width and total tooth material and we get a value which is less than 37 percentage that patient requires extraction. If the value is between 37 to 44 percentage it is like a borderline case and it may or may not require extraction depending upon other parameters that is 37 to 44 and if it is greater than or just 44 not greater than just 44 it is an ideal case extraction is not required. That is a percentage wise analysis and the next thing is if premolar basal arch width is greater than premolar diameter that is the root apacus dimension is greater than the crown diameter that is this is a root apacus diameter root apacus width and this is diameter of crown to crown. So this is greater than the premolar diameter the basal arch that is the arch of the patient is sufficient to allow expansion that it has enough room to give expansion for the teeth that is basal arch width is greater than premolar diameter and if the opposite happens that is if premolar diameter is greater than premolar basal arch width there can be three possibilities the one is which is contraindicated for expansion the expansion will not will not happen and we should not perform any expansion procedure and there are chances of moving the teeth distally the distal movement of teeth may occur and we should go for extracting some teeth so that is under this case so that is all about ashley house analysis it is based on the arch width concept not the arch length and it has four parameters total tooth material basal arch length premolar diameter and premolar basal arch width so that's all about ashley's analysis so i'll come up with which separation in my next video thank you