 Hello everyone, welcome back to another session in dentistry and work. Today's class is about the developmental disturbances of teeth with respect to shape or form. So we have various classification which is seen in crown and root. So let's see the details of developmental disturbances of teeth with respect to the crown. So the disturbances of teeth which is seen in crown, we have nine types. The first one is fusion, germination, ptorodontism, talan's cusp or leon's cusp which is also known as dent's evaginatus. The next one is dent's invaginatus, peglatoral, hechocens incisors, mulberry molar. The last two are seen in syphilis, congenital syphilis whereas in root we have congresants, enamel pearl, dilaceration, flexion and ankylosis. So this is a very very important session because each question will be asked as a short note. So all these are asked because not even one you can keep aside as unimportant, all are important and it is very frequently asked question in short notes. So now let's start with fusion. So what is fusion? Fusion as a picture says it is the joining of two developmental tooth germ. It may involve the entire tooth length or just the root. So two tooth germ which is joining and making or looking like a single tooth but there will be a slight separation between the teeth. So it is a bigger tooth rather than a single normal tooth which adjoining two teeth. The point is there will be two separate developing tooth germ. So that is fusion. So it may just involve the roots or entire length will be joined. So it results in a single large tooth structure. So if it is involving just the roots that will be like cementum and dentin will be shared. Not like this, there will be cementum and dentin will be shared if it is joining at the root position. Suppose if it is like this, so there will be cementum and root sharing. This is crown sharing and if it is happening at the root end there will be cementum and dentin sharing between these two two germ. And fusion is basically seen in lower teeth that is central and lateral or lateral incisors and canines in lower teeth. Next we will move on to the germination. Geminization is nothing but fusion of two teeth from a single enamel organ. So this is two enamel two tooth germ. This is a single enamel organ but it looks like two teeth because there will be a partial cleavage. So it appears as two crowns but with same root canal. From the clinical point of view it appears as two crowns but it has only one root and one root canal. So this is germination, fusion of two teeth from a single enamel organ. So the exact etiology is not known. Possibly it could be due to trauma. So fusion is different, germination is different, fusion is a name itself gives a clue. It is a fusion of two separate tooth germ. It appears as a bigger tooth but germination is it is a splitting of just a crown portion. So there will be a small cleavage and it appears as two crowns. So it has a single root or single root canal. It may have two root canals. Now we have Torodontism. Torodontism is a variation in tooth form. So we have elongated crown and apically displaced fercation. So you can see that the fercation is apically displaced very elongated crown. Similarly the pulp chamber also very elongated. So it results in a pulp chambers that have increased apical occlusal height. So the apical occlusal height is very increased. So you can see the occlusal side and the apical side. Usually it is not this much elongated but this is a longer crown. So since longer crown there will be an increased height of pulp chamber. So it is most commonly seen in Down syndrome and Klein filter syndrome. Basically it doesn't require any treatment that is Torodontism elongated crown. Germination is split crown. This is fused crown. And now we have Talan's cusp. Talan's cusp is an additional cusp which is seen in mostly the lingual side of anterior teeth. Additional small cusp-like structure at the singulum area we can observe in few teeth. So that is known as Talan's cusp which is also known as Den's Evaginatus. So there will be extra growth. So that is known as Evaginatus. So it extends from CEJ to the half of the incisal edge. So this is a CEJ and it extends from half of the incisal edge. So it appears as a small cusp at the lingual portion in the singulum area of upper anterior teeth. That is also known as Den's Evaginatus. So we have two structures in Den's Evaginatus. That is the extra structures which is projecting outward. The Leung's premolar and then Talan's cusp is coming under Den's Evaginatus. Now we have Leung's premolar which is an accessory cusp or a globule which is located on occlusion surface between buccal and lingual cusps of premolas. So this most commonly seen in premolas that's why it's called this name Leung's premolar. So it is nothing but accessory cusp or a globule which is seen between buccal and lingual cusps of premolas. So it can be seen unilaterally or even bilateral conditions also present. So Talan's cusp and Leung's premolar is known as Den's Evaginatus. Now we have Den's Invaginatus or also known as Den's Indend. So tooth within tooth. So that's why it's known as Den's Indend. So it is due to the deep surface invagination, invaginations inward growth of crown or root that is lined by enamel. So it is invaginated. So it is going inside. So we have two forms. One is coronal and radicular. So this deep surface invagination of crown or root which will be lined by enamel. So that will be lined by enamel. This invagination, this is type one, type two, type three or also we have coronal and radicular. So depth varies from slight enlargement of singulum to a deep infolding that extent up to apex. So this is type one, type three is very extended up to apex. So we have three types, type one, type two and type three. So type one is confined to crown. So this is type one, type two is which extends below the CEJ junction and ends in a blind sac. So it ends in a blind sac here. So this is a blind sac and it may or may not communicate with adjacent dental pulp. So sometimes it communicates, this is a pulp. So sometimes it communicates with the pulp. Sometimes it does not communicate. So that is type two. Whereas type three which extends throughout through the root. So see the roots you can see it extends from the crown and it extends downwards towards the root and it perforates in the apical or lateral radicular area. So you can see it perforates here, perforates here in the apical or lateral radicular area without any immediate communication with pulp. So pulp is this red color. So it does not have any communication with the pulp. But it separates or it coming towards the root tip. That is it perforates in the apical or lateral radicular area but without any communication with pulp. So type one is within the crown. Type two is a little more deeper. But it is which is ending in a blind sac but it does not communicate with the pulp. So this is a pulp. Okay. This is a pulp that red orange color. Type three is which perforates in the apical or lateral radicular area. It has perforation in the root area but it does not communicate with the pulp. So that is dense invaginatus or also known as dense indent. Okay. So this is a commonly asked question. Dense invaginatus. You can write Talan's cusp and Leon's cusp or Leon's primolar. And next one is dense invaginatus or dense indent. So it has two names dense indent. So we always get confused with the dense invaginatus and dense invaginatus. So dense invaginatus and dense indent both has i n. So that is how you can remember. Dense invaginatus and dense indent. So you do not write dense indent for dense evaginatus. Okay. So you might be know the answer but writing the proper answer will only get virtue marks. So type one, type two, type three dense invaginatus or dense indent. Now we have pegg lateral which we have seen in our size anomaly that is microdonchia which is seen as a tapered crown especially the lateral incisor. And next is the Hutchison's incisors. Hutchison's incisors associated with congenital syphilis. So in Hutchison's incisors where central or lateral incisors are pegg shaped or screwdriver shaped can see there is a notching at the end and it is widely spaced notching and widely spaced with a crescent shaped deformity. So there will be a crescent shaped deformity. So you can see a crescent shaped deformity. So it is seen in congenital syphilis. Similarly there will be notching notches on their biting surfaces. So always notches will be present on the biting surfaces which is named after so Jonathan Hutchison is a English surgeon who first described it. Now we have Mulberry molar which is also a condition seen in congenital syphilis. In Mulberry molars there will be multiple rounded rudimentary enamel cusp or which is seen on the permanent first molars. So these doft molars with cusp cover with lots of globules or enamel projections gives it a Mulberry appearance. So these two conditions Hutchison's incisors and Mulberry molars associated with congenital syphilis. So that's all about the developmental disturbances of crown that is regarding shape or form. So we learn fusion, germination, torodontism, dense evasinatus. So talons cusp and leung spremolar comes in dense evasinatus dense invasinatus or dense indent peglateral Hutchison's incisors Mulberry molars. So fusion is fusion of crowns, germination there will be twinning or single enamel organ which gives a two crowns. Torodontism is elongated crown, talons cusp seen in lingual part of antedias, leung spremolar are extra globule between the buccal and lingual cusp. Dense invasinatus there will be invasination which has type one, type two and type three. Pheglateral is a converged lateral Hutchison's incisors notched crescent shaped incisors. Mulberry molars there will be enamel globules gives it a Mulberry appearance which are seen in congenital syphilis. Next we have the developmental disturbances with respect to the shape or form seen in root. So I'll come up with that topic in my next video. Thank you.