hey everyone Ryan here and welcome back to our pediatric dentistry series in this video we're going to talk about primary tooth anatomy so the biggest thing to know about primary teeth is that they have thinner enamel than their permanent tooth counterparts we're talking about maybe one millimeter of enamel thickness versus two millimeters of enamel thickness for permanent teeth on average also the enamel is more uniform in depth around the tooth whereas for a permanent tooth it could be a little bit more variable depending on where you're at additionally the dentin layer is thinner and primary teeth as well so this means a couple of things if the enamel and the dentin are thinner then the pulp is naturally going to be larger in comparison also because these teeth have thinner mineralized layers than permanent teeth they're more prone to caries and tooth wear and also to pulp exposure when preparing them for restorations having Finneran amal also means the tooth appears more white note the pearly white tint of these three primary teeth as opposed to the more yellowish tone of this permanent molar and that's due to an increased translucency with a thicker enamel layer so if we look at the cross-sections down here we can appreciate the difference in direction of the enamel rods for a permanent tooth the rods are they tend to be perpendicular to the dentin at the dej and so near the cervical third of the tooth these are these enamel rods start to dip down in a gingival direction whereas in primary teeth the enamel rods point up occlusal II in this direction and that's important when thinking about the differences in tooth Anatomy between these two also note the presence of a cervical bulge this is a prominent cervical Ridge especially at the primary first molar so we can look right here and this part that bulges out at the Museo facial component is the cervical Ridge what I like to call the cervical bulge also the roots of primary teeth are more divergent you can appreciate in this drawing and over here how the roots diverge quite a bit more than they do in permanent teeth which tend to be a bit more parallel or even converging and there's also a small or absent root trunk that's the area between the cej and the bifurcation of the tooth in the primary teeth it's a lot smaller or absent altogether and also important to note these primary teeth tend to be wider Museo distal and shorter incisor gingival II than their successors they're permanent tooth successors alright so those are some high-yield facts to know that primary teeth and the helpful thing here is that a lot of these things bigger pulp whiter and other things that we talked about have to do with them having thinner and Amal so that's definitely the thing to know from this slide alright so let's go through each primary tooth in order and in sequence here and we'll talk about the high-yield facts that you need to know for the board exam for each of these teeth for consistency's sake the mesial side of each of these teeth will be on the right for all these images the distal side will be on the left so for the primary maxillary central incisor this is the widest anterior mesial distal tooth so of all the anterior teeth and the primary dentition this is the widest museo distally it's the only anterior tooth where its width is greater then it's height and this is actually true for both dentition 'he's so of all the anterior teeth in both the primary and the permanent dentition this is the only one where it's wider than it is tall er so that's pretty cool it also has prominent labial and lingual cervical ridges we can see the labial cervical Ridge right there the primary maxillary lateral incisor luckily for us no high yield facts here so we'll keep moving on the primary maxillary canine is the widest anterior tooth in a facial lingual direction so that's going in and out of the screen so of all the anterior teeth the primary maxillary canine is the widest facial lingually it's mesial cusp Ridge over here is greater than the distal cusp Ridge in length and that's true of the maxillary first premolar as well the cusps tip as a result of this difference in length is offset to the distal remember mesial is on the right distal is on the left it also has a longer and sharper cusps than the mandibular canine and even its successor the permanent maxillary canine all right next we're gonna go to the molars there's a lot of facts to know about the molar sort of spend most of our time on these I love these illustrations from pocket dentistry calm but note that all the molars are going to be displayed from the lingual or the palatal view so if we look down here from the occlusal view the crown resembles the maxillary first premolar with an added small distal component over here so a great way to remember this tooth is that the maxillary first premolar is the tooth that will eventually replace this primary tooth so it's cool that it resembles it in some way from the from the occlusal view you might be able to appreciate this prominent cervical bulge that we talked about a little bit earlier in the video and you can really see it pretty good from the occlusal view how it sicced out like that and you can't fully appreciate this from the lingual view unfortunately but the cej dips more on the mesial half of the tooth than on the distal half and that's in order to make a room for this cervical bulge this is also true for the primary mandibular first molar as well the three root form resembles the permanent maxillary molars so having a palatal root Museo facial and distal facial or mesial-buccal distal buccal roots is the same kind of structure the same kind of arrangement that you'd see in the maxillary molars in the permanent dentition as well all right let's move to the maxillary second molar of the primary dentition this is the widest primary tooth in the facial lingual direction this crown resembles the permanent maxillary first molar so this one's not representing so much the its successor but it's more representing the tooth that's going to be right next to it so in the transition the mixed dentition you're gonna see this tooth right next door to this primary maxillary second molar or I should say you'll see this tooth right next door to the permanent maxillary first molar and how does it resemble that tooth exactly well it has a cusp of karabell II on the mesial lingual side of the tooth it's actually the only primary tooth with a cusp of carob belly as well as an oblique Ridge and a distal lingual groove so these things are very unique to this tooth the cusp of care belly again is palatal to the mesial lingual cusp tip the permanent maxillary first molar and also in this primary tooth it's also the last primary tooth to erupt which we know from our eruption pattern we went over in the first video in the series all right so that's enough about maxillary primary dentition let's go to the lower so the primary mandibular central incisor is the smallest tooth in a facial lingual Direction like in the permanent dentition it's also the most symmetric of all the teeth here again the mesial is still on the right distal is on the left primary mandibular lateral incisor looks cool but we have no highlights facts and the same for the primary mandibular canine so let's keep moving next we have the primary mandibular first molar and this is by far the most unique tooth in the entire dentition it's the most unique and frankly primitive looking tooth it doesn't look like any other human teeth it almost looks like a dinosaur molar because of how how stretched out and wide it is in a mesial distal direction but if we look carefully it looks like the second or the mandibular second premolar on the distal aspect and maybe like if you squint your eyes half of a mandibular first premolar on the mesial half it looks like they were smushed together to create this thing so they're very strange-looking teeth it has the most distinct Museo facial cervical Ridge or cervical bulge which we can really appreciate from the occlusal view and it also has the most distinct transverse Ridge coming across here kind of where the two smushed premolars meet together it's the most difficult primary tooth to restore as you can imagine there's all these prominent ridges and like this transverse Ridge here and that cuts right through the center of the tooth and can make an occlusive preparation rather challenging the cej dips more on the mesial half resulting in an s-shaped cervical Ridge now like I eluded to before this is the same thing we see in the maxillary first molar in the primaries in Titian again we're looking from a lingual view here so you can't really appreciate it but take my word for it the CH a kind of dips down like this to accommodate this large cervical bulge it has a distal triangular fossa right in here and it has this mesial-lingual ice-cream cone cusp which is the highest and the sharpest cusps on this tooth however the mesial buccal cusp is the largest in size of all the cusps so sometimes the board exam will ask which is the largest and I would answer mesial-buccal but if it says something like highest or sharpest then that's pointing to the mesial lingual cusps so I see sometimes a lot of confusion about that so definitely take note of that so you can keep that clear if you get asked about that there also four cups total and for pope horns to coincide which with each of those cusps also note that like in the maxillary dentition the maxillary molars we saw there is a three root form and here we see a - root form that's also consistent and resembles the permanent mandibular molars alright and we're up to our very last tooth the primary mandibular second molar this one is the widest mesial distal tooth of all the primary dentition the crown resembles a permanent mandibular first molar except that the mesial-buccal the distal buccal and the distal cusps are nearly equal in size whereas for the permanent mandibular first molar the distal cusps especially is a lot smaller so it's kind of interesting that we saw this is also true for the primary maxillary second molar where we had this is the one resembling the permanent first molar and then same thing on the lower this is the one that's kind of resembling the permanent first molar that's going to be erupting right next to it during the mixed dentition so that's pretty cool this one has five cusps just like the permanent first molar and two roots where the mesial is a bit bigger with two root canals alright so that's it for this video guys thank you so much for watching please like this video if you enjoyed it and subscribe to this channel for more on dentistry if you're interested in supporting this channel and what I do please check out my patreon page thank you to Michael Raja Reb Boyd Lea nila bunger Zoo here and Nani David Jayden Janet Isabella called this alley bench dear Jacob K the DRF now II and all my 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