 Hello everyone, welcome back to a new session on dentistry and more. Let's continue our periodic sessions. So last session I was talking about first transitional period and the changes happening in the oral cavity during this particular period that was exchange of primary incisors by permanent incisors and the eruption of permanent first molars. So while the eruption of permanent first molars is concerned, there is lot of occlusion changes is happening that we had seen from flesh terminal plane to maceal step to distal step. So in this video I will be explaining about what happens exactly when the permanent molars are erupting and how it is getting fixed to its final position utilizing certain spaces. So one of my video was explaining about primate space and leeway space. So hope you have watched that video. So that might help to understand this video completely because the concept is all about primate space and leeway space. So to brush up the idea primate space is nothing but a simian space, it's also called a simian space. It is space present between canines anterior to canine in maxillary arch, not this one. Anterior to canine and posterior to canine anterior to canine in maxillary arch and posterior to canine in mandibular arch that is between canine to lateral incisor in maxillary arch and canine to first deciduous molar in lower arch. This space is known as primate space. So most of the cases when first molars are erupting it utilizes the primate space and finally getting to class 1 molar relation that is its final position. How it is happening is eruptive forces of first permanent molar pushes the deciduous molars to utilizes the space and provides space for these maxillary and mandibular treat that is first permanent molar. So these forces pushes the deciduous molars to utilizes the primate space present in the upper and lower arch and gives space for the permanent first molar. So that is the early misal shift. It happens during early mixer tendation. So this happens during 6 to 7 years because most of the time the first molar syrups during that period. So it utilizes primate space, closes the primate space and arriving to class 1 molar relationship that is early misal shift concept. So what is late misal shift concept that is happening during the late mixer tendation period. So late misal shift is happening during the late mixer tendation period when primate space is absent this concept will be working because there is no space for this primary no space provided by this primary rendition for the first permanent molars. So that time it utilizes the leeway space. leeway space is nothing but the difference between primary canine and molars and its successes that is permanent canine and primolars. So that is the difference. So that difference is known as leeway space it is the combined miso distal width of primary canine and molars with against the permanent canine and primolars. So that space will be utilized but what happens is it is utilized only after the exfoliation of primary molars. So primary molars usually exfoliated during 10 to 12 years. So this happens at late mixer tendation period 10 to 12 years. So once these teeth are exfoliated the permanent first molars drift misily. So you can see the aromax it drift misily and utilizes the leeway space and reach up to class 1 molar relation. So here it is different concept it utilizes the primate space but here it is utilizing the leeway space. So primate space and leeway space is happening early misial shift and late misial shift this is during early mixer tendation maybe 6 to 7 years this is 10 to 12 years. The basic difference is utilizing the primate space and utilizing the leeway space. So that is all about the misial shift early misial shift and late misial shift and how the permanent molars are getting its ultimate position and the adult oral cavity. I will come up with a new video thank you.