 Hello everyone, welcome back to another session on dentistry and more. So today we have tooth model analysis. So a model analysis is like the study of dental cast which helps to study the occlusion and dentition from all three dimensions and analyze the degree and severity of malocclusion. And also we can derive the diagnosis and also plan the treatment. So there are a lot of advantages for model analysis because we get a three dimensional records of patients dentition which is clinically it is very difficult to obtain and occlusion can be visualized from the lingual aspect and it provides a permanent record for inter maxillary relationship and also helps to motivate the patient as they can visualize the treatment prognosis can take before and after cast and we can motivate the patient and also we can transfer the patient to another dentist if we have the models with us. So that also is a very crucial thing in model and now we will start with the model analysis. So we have various model analysis. Some are for permanent teeth and some are for deciduous teeth. So the permanent teeth model analysis, the most important one is the Bolton analysis. Then we have Pones analysis, Ashley Howe analysis, Carey's analysis, Arch perimeter analysis whereas mixed dentition analysis we have Moe's analysis and Tanagha Johnson analysis. Now let's start our analysis that is Bolton's analysis. It is a ratio between meso distal width of maxillary and mandibular teeth. Bolton we have calculated a constant proportion. So we found out that a constant proportion is present between upper and lower dentition when the occlusion was perfect. And that proportion is 91.3 percentage and 77.2 percentage. It is actually determining the tooth size discrepancy between the mandibular and maxillary teeth and checking by checking the meso distal width of maxillary and mandibular teeth. So according to Bolton he says that the mandibular meso distal dimension will be of 91.3 percentage of maxillary molar to molar that is 6 to 6 and canine to canine it will be 77.2 percentage that is if the maxillary teeth are 100 the mandibular molar to molar will be 91.3 percentage and mandibular canine to canine will be 77.2 percentage. So that is idealistic ratio. So how do we calculate this ratio? So two ratios are put forward in by Bolton in his analysis that is overall ratio and anterior ratio. So overall ratio is the calculation is sum of mandibular 12 teeth and sum of maxillary 12 teeth. So we divide mandibular 12 by maxillary tool that is a meso distal dimension and we take percentage by multiplying 100. So you can see that it is molar to molar, left molar to right molar and left molar to right molar in maxillary and mandibular tool. So ideally speaking that should be 91.3 percentage that means the mandible is lesser compared to the maxilla we know that mandibular dimensions are lesser and it is 91.3 percentage. So mandible is coming here in numerator and maxillary in denominator. So if the calculated value is greater than 91.3 percentage you know that this is more that is mandibular tooth material is excess because this is a numerator and if it is less than 91.3 percentage that is the calculated value is less than 91.3 percentage. So this would be more that is maxillary tooth material is excess because this is in denominator. So overall ratio is calculated from left molar to right molar on maxillary and mandibular tool. So how do we calculate the excess material? The excess material the sum of maxillary tool if it is maxilla maxillary excess we need to calculate in this form and mandibular excess we need to calculate from this form. Since maxilla is excess it should be mandible misodistral width should be subtracted from maxilla because maxilla is more. So sum of maxillary tool minus sum of mandibular tool divided by 91.3 into 100. So we get the maxillary excess material. So if mandibular excess material that is if the ratio is greater than 91.3 we should take subtract the maxillary tool from mandibular tool. So all I am speaking about misodistral dimension. So sum of mandibular tool minus sum of maxillary tool divided by 100 into 91.3 percent. So we get the excess material. So this is how we calculate the excess material. So what is the importance of this understanding the excess material? So we can do extraction on mandibular teeth or maxillary teeth to achieve proper inter digitization or over jet or over bite and alignment of the teeth. So whereas anterior ratio so anterior or overall ratio we can calculate the excess material and we can do extraction or other changes in maxillary or mandibular teeth. So anterior ratio the same thing we apply on 6 teeth. So here we applied on 12 teeth that is molar to molar 6 to 6 here we are doing it on canine to canine on both upper and lower teeth that is canine to canine anterior ratio is sum of mandibular 6 divided by sum of maxillary 6 into 100 we get 77.2 ideally. So if it is greater than 77.2 since it is a numerator the mandibular teeth the mandibular excess material and if it is less than 77.2 the maxillary tooth material is excess. So the same way we can calculate the excess material that is sum of maxillary 6 that is missio distal dimension minus sum of mandibular 6 divided by 77.2 into 100 if the maxillary excess is there. So always think that if maxillary excess should be found out this will come first because this is more and mandibular material is subtracting from the maxilla. So if mandibular excess is there this will come first and maxillary 6 missio distal dimension will be subtracted from mandibular 6. So divided by 100 into 77.2 if mandibular material is excess. So that is how we calculate the excess material in anterior ratio and in overall ratio. So this is basically understanding the tooth size discrepancy between maxillary and mandibular teeth. The 2 ratio or the 2 percentage is to remember the 91.3 percentage and 77.2 percentage in case of 12 teeth and this is not 12 teeth that is 6 teeth. So this is 6 teeth that is canine to canine this is molar to molar. So that is about Bolton's analysis which is a permanent tooth analysis put forward by Bolton. So I will come up with another analysis in my next video. Thank you.