 Hello everyone, welcome back to another session in dentistry and more. So we are continuing our dental anatomy sessions. So last session was about mantibular central incisor where we learnt few differences between central and lateral incisor. So mantibular lateral incisor again they are two in number, mesial side we have the mantibular central incisor and on the distal side we have canines. And it has a slightly wider dimension mesiodistally compared to the central incisor and it is slightly even larger in all aspects than the central incisor which complement the central incisor in function. And the distal contact is with the mantibular canine that is a deciduous mantibular canine until the tooth's exfoliation and then the contact is shared with the permanent canine because it irreps very early that is around 7 to 8 years. That time it has contact with the deciduous mantibular canine. So mantibular canine the newer one irreps around 11 years may be 10 to 11 years. So once it irreps the contact will be with the permanent mantibular canine. So the tooth numbering the universal system 18, 9, 16, 17, 24, 25, 32. So it will be 23 and 26, the Zygmorty system is 2 and 2, FTA system is 3, 2 and 4, 2. So the chronology, the first evidence of calcification is 3 to 4 months, crown completion by 4 to 5 years, eruption by 7 to 8 years and root completion by 10 years. Dimension the 9.5 and 14 for crown and root, 5.5 and 4 for the mesiodistal at crown and cervix, the same on distal side sorry the labial lingual or the buccal lingual is 6.5 and 5.8 at crown and cervix and the curvature line is 3 and 2 on mesial and distal side. So the labial aspect incisal margin it may slope slightly gingivalent towards the distal. So that results in a distal incisal angle that is more rounded than the same angle of central incisor because of this gingival sloping towards distal and this feature creates a slightly shorter distal margin when compared to the mesial outline and contact area on the distal is more servically located than on the mesial this creating a more servically located height of contour on distal outline and both height of contour are still incisal third and lingual aspect the lingual outlines are similar to those of labial aspect and the structure of lingual surface are similar to their counterparts on the central incisor except singulum which is more offset to distal can see it here and as a result curvature of cervical iron is also offset distally and concavity in lingual aspect is likely more when compared to the mandibular central incisor and mesial marginal ridge is more curvature compared to the distal marginal ridge and regarding the mesial and distal aspect the two surfaces are similar to their counterparts on central incisor with few minor exceptions that is a lateral distal surface is slightly shorter incisor servically than the mesial surface and both cervical line curvatures are slightly lesser than their counterparts in the central incisor and the mesial cervical line shows greater incisal curvature than the distal and a distal contact area height of contour is more servically located than on mesial in incisal third the distal contact area is very near to the junction of incisal and middle third and is most servically located of any mandibular incisor contact that is a incisal third the distal contact area regarding the incisal aspect the incisal edges not straight mesiodistally as it is in the central rather it curves towards the lingual in its distal portion and the lingual contour that is a singulum appears displaced towards the distal all having that distal convergence of distal movement of the crown so these factors give crown the appearance of being slightly twisted on its root so best identifying fit from central incisor that is the easiest method can differentiate from central and lateral incisor that is a slight distal twisting and regarding the root root length is normally a little greater than in the central incisor and root is also slightly thicker and wider and the root concavitys may be found on the mesial and distal root surfaces and if present concavity in distal is usually more pronounced so anomalies are rare but occasionally a bifurcated root is found with respect to the mandibular lateral incisor so the difference between mandibular central and lateral incisor we already discussed with the mandibular central incisor so next we have mandibular primolas because we finished already the mandibular canine session so I will come up with mandibular primolas thank you