 Welcome back to a new session on dentistry and work. So today we are seeing about the difference between primate space and leeway space. So this is very important to understanding the occlusion concept in our dentition because the next video will be seeing mesial shift, the early mesial shift and late mesial shift how the permanent molars are getting into its final position utilizing the primate space or leeway space. So it is nothing but the space available and which is being utilized by the permanent molars to accommodate to its final position. So let's move on to primate space it is also known as simian space or anthropoid space which is present in mostly 87 percentage of the cases. So it is present between an upper arch between the lateral incisor and canines that is anterior to canine whereas in lower arch it is present between canines and first molars that is posterior to canine. So it is easy to remember this way anterior to canine in upper arch and posterior to canine in lower arch. So this canine lateral in maxilla, canine and molars in mandible. So this is primate space or physiologic space which is utilized by the permanent molars because once it erupts the erupting force pushes these deciduous molars into this space and giving space for this permanent molars. So that will be seeing in next video. So that is the primate space. So what is leeway space? Leeway space is nothing but it is the difference between the mesiodisital dimension that is a mesiodisital width of primary canine and molars primary canine and molars with against its successes that is permanent canine and primolars. So that is the difference between primary canine and primary molars that is first and second molars against permanent canine and first and second primolars because the successor deciduous canine will be replaced by permanent canine. The first and second molars will be replaced by first and second primolars. So that is the leeway space the mesiodisital difference. So definitely it will be larger in deciduous dentition and this space will be utilized by permanent molars where the primate spaces are absent. So this will be happening only when the deciduous molars are exfoliated that will be seeing in a mesioshift concept. So this is nothing but the difference between mesiodisital width of primary canine and molars against permanent canine and primolars. So this will be utilized in late mesioshift to reach to class 1 occlusion when primate space is absent. So this is maxillary it is lesser 0.9 mm per side that is 1.8 mm total whereas in deciduous it is 1.7 mm and it is 2.5 mm it is average so 1.7 mm in lower arch and 3.4 mm in total. So upper arch it is 1.8 mm and lower arch it is 3.4 mm which will be utilized by the permanent molars if primate space is absent for to getting to its final position. So that is primate space and laver space. This is important in understanding the concept of mesioshift that is early mesioshift and late mesioshift. So next video I will be explaining about early and late mesioshift. Thank you.