Morph Maxillary Molars PDF

Differences max and man molars - Molars are the largest and heaviest load-bearing teeth in mouth - Major differences between maxillary and mandibular: - 1. Geometric shape: occlusal aspect more ovoidal and in the buccolingual and mesiodistal distance very similar to each other...

Differences max and man molars - Molars are the largest and heaviest load-bearing teeth in mouth - Major differences between maxillary and mandibular: - 1. Geometric shape: occlusal aspect more ovoidal and in the buccolingual and mesiodistal distance very similar to each other in maxillary molars but when look at mandibular molars, see a huge difference between buccolingual and mesiodistal, mesiodistal is much wider and geo shape is more elongated and rectangular - 2. Cusp distribution: Share feature of having 5 cusps, but distribution of the cups is completely different - Mandibular molar=see 3 buccal cusps that are all part of occ plane - Maxillary molar, see 1 extra cusp on the mesiolingual which is the cusp of carabelli which isn't part of the occ table necessarily - 3. Presence of Oblique ridge: 2 ridges, and crosses the occlusal plane obliquely, this feature is UNIQUE to the max molars, won't find anywhere else: if see oblique ridge on tooth, know you’re in the maxillary arch Maxillary 1st molar: coronal portion - Max 1st molar has cusp of carabelli, UNIQUE to only that tooth - Location is on the lingual surface of the mesiolingual cusp- not really part of the occlusal plane - We call it a Non-Functioning cusp (not non-functional bc that is related to occlusion), but this is not part of the occlusal plane!!! - Mesial outline straighter, distal outline more convex - 4 functioning cusps, mesiolingual largest - 1-Mesiolingual, 2-mesiobuccal, 3- distolingual, 4-distobuccal - (3 and 4 we will see differences in distribution when move to 2nd and 3rd molar) - Flow between the teeth: start w the Central incisors, very thin incisal edges, and start to see wider buccal lingual dimensions until hit first molar, really wide tooth and then tapers down into the 3rd molar - Following same small, larger, then small: individual tooth having that feature too- mesial half of tooth is a little bit wider than distal half of tooth and mesial surface bit flatter than distal which is more convex and compact - Mesiolingual cusp largest one, the one that sits in fossa and grinds the food, very heavy-bearing loading cusp, very wide and blunt so smushes food - 1. Mesiolingual, 2. Mesiobuccal - Largest maxillary tooth - Crown size, shorter than PMs - Can see that the mesiodistal, buccal-lingual dimension from occlusal view is a bit different, but it is very close, giving it the squarish or rhomboidal feature - Buccal surface is trapezoidal geo shape: shorter side trapezoid from the buccal is at cervix:cervical side shorter than occlusal side (different from proximal) - 2 Major (central and distal fossa) and 2 minor fossas (mesial and distal triangular fossa): fossa= space or concavity where the tooth dips into the valley - Central fossa, distal fossa, smaller triangular fossa by the marginal ridge and a smaller one by other marginal ridge - 1st maxillary molar has largest distolingual cusp - One of the MAJOR DIFFerences talk about when move from 1st, 2nd, and 3rd: Largest distolingual cusp - Oblique ridge connecting the distal buccal to the mesiolingual cusp - One cusp has a triangular ridge and when 2 triangular ridges come together and blend, form diff types ridges: transverse or oblique (transverse in PMs) - Oblique ridge unique feature in this tooth - Most prominent on the maxillary first molar - Thick oblique ridge, holds tooth together, thick enamel layers and supports tooth in its functionality - If prep tooth for occlusal caries, want to preserve the oblique ridge as much as possible - In the buccal aspect, the mesiobuccal and distobuccal cusps are equal height but difference is that the distobuccal cusp is much sharper than mesiobuccal - Buccally and lingually there is a defined developmental groove: - Buccal developmental groove and lingual developmental groove AKA distal lingual groove (DLG) - Starts from distal pit and it is continuous all the way down to the lingual surface and see it extending to lingual surface on palatal surface picture - There is a difference between a fissured groove and a non-fissured groove - 2 major grooves: - DLG that extends from the distal to lingual, usually one continuous groove, nothing crosses it - Buccal groove more faint, more of a depression than an actual fissured groove - Central groove, buccal groove and DLG - Central groove; strong presence, extends towards buccal, sometimes continuous w buccal groove, sometimes not as strong but then also it continues into the mesial triangular groove: if prepping that portion, going to be more of a crescent shape and if prepping the distal, going to be more of an L shape?? going through lingual surface and typically they are very separate - Buccal cervical ridge is not as prominent as in the max 2nd molar - One of the strong features that we see in the 1st molars, both max and man, is this strong buccal-cervical ridge, - thickness of enamel supporting functionality of tooth - See a good prominence of the cervical ridge on the 1st molar - A little bit less prominent than the 2nd max molar and sometimes it is not present in the 3rd - Ridges: Oblique ridge, buccal-cervical ridge, strong mesial and distal marginal ridge on the occlusal plane - Mesial slope of distobuccal cusp meets the distal slope at 90 angle, makes sharper than mesiobuccal cusp - Carabelli cusp can be larger and overflow into mesiolingual, variation presentation very variable, no function necessarily but something see mostly on 1st max molar - 1st maxillary molar to erupt - 5 lobes on occlusal plane - Concavity on the distal surface of crown - Mesial and distal contact areas are both in the middle third but tiny offset applies to all teeth: - mesial bit more occlusal and distal bit more apical - Cusps and sizes, fissures and grooves, contacts areas, ridges - See a slight difference in the height of the buccal and lingual cusps: - Buccal cusps of the maxillary molars, bc they aren’t the one sitting in the fossa, are a little bit sharp and pointy (the non functional cusps) but the ones that sit in the fossa and are part of primary conclusion would be the linguals of the maxillary, and why they are a bit more broad, but more blunt at the tip (larger, but more blunt) - Buccals are longer and sharper, and the linguals are a little bit more wider in size, but more blunt at the tip - MAXILLARY 1st ROOTS - Trifurcation: have 3 roots - largest root is palatal (lingual root, but use palatal bc embedded into palate) and smallest is distobuccal - Palatal root, mesiobuccal and distobuccal root - Roots strongly developed to withstand occlusal forces - Root trunk on side of root mesially and distally within confines of crown - Lingual root almost centered between roots - All 3 roots, see in lingual view (and facial) - Palatal root is similar to the root of the central incisor, although it has a little bit of a mesiodistal spread to it (can see that it is a little bit wider mesiodistally than buccolingually), but it is a large, rounded root with a very large centered canal - Cross section: see elongation and then a centered canal in the middle, not as conical as see in the CI - In distal aspect, can see all 3 roots due to the ever so slightly smaller size of the distobuccal cusp, from the mesial, can see that the mesial is much larger so it overshadows the distal but from the distal aspect, you can see a little bit of the mesiobuccal - In mesial aspect, only 2 roots visible (mesiobuccal and palatal) - Roots are designed to the anchor tooth into the bone, sometimes those roots, especially palatal one, may be long enough to get into the sinus, intrudes into the max sinus so strength shown in the architecture of the roots - Root canals: - Palatal: see a very large, centered canal; easy to find, very defined - Mesiobuccal: Very high failure rate of root canals for maxillary molars - more often than not, there is a 2nd root canal in the mesiobuccal (MB2) - MB2 buccal root, because sometimes it has a little bit of a wider buccal-lingual dimension and a little bit of concavity as well, if we cross section it, have a small root canal and underneath it, there is a little tiny second root canal (a lot of times it is missed) but now we look for it - Once find major canal in the mesial buccal, might be able to see miniature, pinpoint, needle-tip canal that if fail to find, then root canal fail and tooth re-infected - Distobuccal: one small canal, does not show variation of 2 canals - Roots are not straight, usually curved distally (apex pointing to the distal) - Not necessarily all the roots in the 1st maxillary molar ! - Roots tipping towards the distal: applies more to 2nd molar not the 1st - Think of furcation as a tulip or flower, base and bloom out and tuck back in: roots spreading out as they furcate then going back to hug bone - Distal buccal root: flares out to the distal and then the apex points towards the mesial - Mesial root: spreads out and then tucks back in to the distal - Palatal root: spreads out and then curves back into buccal - Proximal view: root trunk height shorter size and where separates, strong divergence of root - Root trunk: - Furcation happens earlier in the 1st and later on up root in the 2nd then the 3rd - Shorter and actual roots after the furcation are longer (furcation happening earlier, why root trunk shorter and actual, single roots are much longer) - Mesial buccal root on the mesial aspect is broad and flattened, about 2/3rds the crown width and lingual root projects outwards at the middle and apical thirds - Lingual root is the largest root and the roots are very well differentiated - Buccally, deep developmental groove on root trunk stemming from furcation of buccal roots - Palatal root on lingual profile has a prominent depression - Mesial buccal root is a little bit larger than distobuccal root so usually don't see distobuccal root form mesial aspect - Palatal root is the longest of all the max molars - Most of the times we see 3 roots, vs the mandibular that we typically see 2 (exceptions) - Palatal root longest, but mesiobuccal and distobuccal are similar in length and look symmetrical, going in opposite ways MAX 2nd molar: how the 2nd is different, what things change - 2nd molar is larger in dimension than the 3rd molar - In size, see that the 1st is the largest, 2nd slightly smaller, 3rd much smaller - If see an oblique ridge and a cusp of carabelli, then know its first automatically - 2nd and 3rd dont have carabelli - The roots are more nearly parallel and inclined distally than the first - The roots are a little bit more straight, they don't have that nice flare out and curvature back into the center of the tooth - All 3 have that distal inclination a little bit, much more straight and closer to each other, and smaller in size - 2nd molar: Crown shorter and narrower mesiodistally compared max 1st molar - buccal-cervical ridge not as developed - Strongest presentation in 1st molar; buccal cervical ridge and not so much in 2nd and 3rd - Distolingual groove does not extend as far cervical or mesially as max 1st, - Distolingual groove is a little bit smaller in size - Distolingual cusp is less developed than 1st maxillary - in 2nd, still see distolingual cusp - In 3rd molar: distolingual cusp less developed and can even be missing completely - One of the major things that happens in addition to size is the distolingual cusp: - Distolingual cusp is much smaller in size in 2nd molar: mesiolingual still largest, mesiobuccal still the 2nd largest, but the distals relationship shifted: - Distobuccal still at the sameish size - But since the distal lingual is much smaller, then distolingual cusp is 4th in size - DLG shrinks down with the distolingual cusp - 3rd molar: entire distal lingual cusp is gone and if gone, there is no groove so DLG and distolingual cusp are gone and leaves us with heart shaped geo shape bc section of tooth hasn't developed - So have 1 large centered lingual cusp and 2 equal size buccal cusp - 2nd molar has a higher prevalence of supplemental grooves, more wrinkled appearance - See much more secondary anatomy on the occlusal surface - Bc the distolingual cusp is reduced, heart shaped 3rd and 2nd molar is rhomboidal occlusal surface - 2nd molar has 4 lobes compared to potentially 5 in 1st molar, and 3rd molar has 3-4 lobes: - 3rd molar: if it only has 3 cusps, then it would develop from 3 lobes but if it has a distolingual cusp then it develops from 4 lobes - Distal lingual cusp gets smaller as move maxillary 1st to maxillary 2nd molar - Max 3rd molar often develops as developmental anomaly - Lateral incisor being the rebel of the dentition, has so many diff presentations, can be missing all together but lateral incisor is the 2nd most common to have variations. - Max 3rd molar is the 1st one to have variety of presentation - vary missing from all together - sometimes look like small rudimentary tooth or peg tooth or tiny irregular, circular occlusal surface with just 2ndary anatomy, very wrinkly appearance on occ surface, no definition to it - can develop and specialize more in its presentation to be heart shaped as most common one see - Can present as a miniature 2nd molar as well and see tiny bit distal lingual cusp and see very faint DLG, but can present as a 2nd molar as well - Differentiate 2nd from 3rd if 3rd is presenting as 2nd molar - Tell by the root - One of the features that will also be different from the mandibular: from the buccal surface, the trapezoidal shorter on the cervix and wider on the occlusal. on the proximal aspects, the trapezoid is opposite: the widest portion is at cervical and tucks into occ portion - For mandibulars, see lingual inclination so more of a parallelogram or rhomboidal bc all man teeth have lingual tilt to it - From the occlusal aspect, the mesiobuccal and mesiolingual cusps just as developed as 1st max molar but the distobuccal and distolingual cusps are smaller and less developed - Arches narrowing down posteriorly so mesial portion and the most mesial tooth is larger and then starts to narrow down - Roots can be fused into 1 in the 3rd molars: common - 2nd molars, can see roots, they are close together, sometimes fuse, sometimes furcation doesn't happen until past half of the root length but still see tiny bit of separation, palatal bit more separate form the buccals but 3rd molars, although the root canal might not be a single centered canal, you still see bit complexity in root canal system but the roots are so close together sometimes, they just fuse, don't have time to grow and separate from each other - Still see from buccal side, the buccal groove and lingual side, the distolingual groove but less seen on lingual side - 3rd molar has no distal contact and the root trunk height of 3rd molar is much larger than other maxillary molars - No more distal teeth - Root trunk longer since furcation happens later if it happens all together - Big indicator of having 1st molar compared to other two is presence of cusp carablli and oblique ridge - 3rd molar presenting as a 2nd molar: way differentiate is bifurcation vs trifurcation plus the larger root trunk height in the 3rd molar and that the roots aren't as spread apart as they are in 2nd molar  - Occlusal portion of 2nd and 3rd, cusp carabelli gone, DLG and distolingual cusp are starting to get smaller, sometimes disappear all together, geo shapes diff, size def diff, roots flare and furcation point and also root trunk also start to change - 3 ridges on maxillary 3rd molar (lingual cusp ridge, mesial marginal ridge) - no oblique ridge bc nothing distal to it - If distolingual cusp and groove are gone then the oblique ridge turns into distal marginal ridge basically - 2 buccal cusps, mesial marginal ridge, lingual cusp really large, and then distal marginal ridge Histology of pits and fissures - Groove: creek, deepest portion valley - 2 diff types of grooves: - fissured groove - non-fissured groove - and how relates to max molars - Fissured groove: - Groove deep into the dentin in maxillary 1st so means it is a fissured groove - Groove easier to clean (one on right) - Fissure groove, deep, if bacteria gets in and has right environment, then very easy for that fissure to get decayed: - need to know bc have to be aware which grooves are typically fissured and which groove are typically not fissured - 3 possibilities of decay: in a fissured groove - Can see that the fissure is so deep that it almost gets to touch DEJ - The depth of the fissure will start to decay but tip (occlusal portion) isn't showing any problems yet although something is happening at the depth of it - If leave this and it gets deeper, can see that the surrounding of the fissure starts to break down: all this white stuff is decalcified enamel and once passes DEJ, it is too late, going to keep going no matter what we do - If at first stage, can use sealants to seal that fissure: not indicated for everybody bc anatomy tooth sometimes does not have deep fissure - If see deep fissures and plaque, hard for pat to clean, given fact there is no decay, make sure no decay in the fissure and make sure it isn't, then you can go ahead and seal it: - Sealant: it is very diluted composite, not filled, thin material that flows into fissures and can sometimes get into depth of fissure by capillary action, - Condition tooth, etch and bond and then place thin layer of sealant and light cure it and block fissures and prevent any caries from happening - start pits and fissure sealants as early as we can see the tooth, especially the first molars, if have complete access to occlusal surface (not partially erupted) then indicated for us to seal the fissures - Can do in adults as well  - If we know that this groove is prone to be a fissured groove, that means if a portion of it is carious, then it is probably going to spread through the rest of it then we need to know what the design of my prep is going to look like - For Maxillary molars, BUCCAL groove=typically NOT FISSURED - have CENTRAL groove, which is most of the time FISSURED, this is where caries start and it extends a little bit between the buccal cusps but it fades out when it gets to the buccal - BUCCAL, can see a tiny indentation or a concavity but doesn't catch when you go over with explorer, can feel the dip, but it is nice and smooth so it is a NON FISSURED GROOVE - LINGUAL groove of maxillary molar, most of the times this groove here will catch decay because it is a FISSURED GROOVE - Bc the DLG is continuous from the distal pit all the way to the lingual surface, if decay starts somewhere, it just keeps spreading through it all and even if the decay is not necessarily spreading, if you open a portion of the fissure, you want to open the whole thing as a preventative measure (it's all continuous) - If prepping a fissured groove, want to include the whole groove - Mandibular molar, opp true: - BUCCAL groove=often times is FISSURED and there is a really deep pit - If decayed, have to open whole fissure and pit and include all of the groove - LINGUAL groove=NOT A FISSURE - typically only 1 groove separating the cusp tips, but it is very rare (not impossible) to see any decay in the lingual groove of the mandibular molar - Maxillary molars have FISSURED grooves on the DISTAL LINGUAL and NON FISSURED grooves on the BUCCAL - Have lingual fissured groove and non-fissured buccal grooves - Mandibular molars have FISSURED grooves on the BUCCAL and NON FISSURED groove on the LINGUAL (opposite max) - Buccal grooves are fissured and lingual grooves are not fissured - CENTRAL groove is FISSURED, alongside the lingual and buccal depending on if max or man - Most occlusal grooves are typically fissured, anything part of the occlusal plane is typically fissured, why we have a lot of occlusal caries if the patient is prone to it and once starts in one place, then it spreads - Caries prep is going to be following the fissure Teeth: - Max bc 2nd PM smaller than 1st and left because distal side on right side of tooth, see lingual distal groove and less developed one on 2nd molar  - 1st PM was largest so upper left and molars, distal lingual groove less prominent 2nd molar so left side - Mesial lingual cusp larger for 1st molar, max based on PMs - Does Not have cusp of carabelli - Diff in sizes - Max arch 1st PM bigger than 2nd - Left bc mesial cusp is on the left side - Direction central fossa and distal fossa, telklk direction M and D sides and lingual groove where distal fossa is then this side has to be buccal - By pointing out DLG, got sides right - DB larger than DL always but book says something different: but agree that bc DL cusp not part occ lane most times, not all there or developed so in this pic - Book says DL larger so go w it - Know both do exist: sometimes DL cusp, smaller not part occlusal plane and sometimes it is Tooth 2 - Right side tooth developed DL groove than one on left - #2 and #3 by DLG and taller buccal cusp - Cusp carabelli next to groove, faint though Tooth 3 - #15: Max left 2nd molar, smaller DL cusp and more heart shaped than rhomboidal - #15: DL cusp present but not as pronounced ot be 1st molar and heart shaped occlusal crown outline - #15 and more developed DL cusp think 2nd molar and left bc of the buccal and central developmental groove being more mesial than distal - Or 16 bc heart shaped and 3 lobes more prominent - Left: DLG - DL smaller, rudimentary so 15 and 3rd molar, 16, 3rd molar heart shaped and no DLG or DL cusp but if variation 3rd molar resembles 2nd molar possible - If tooth i hand and rest story, one thing help us differentiate 15 or 16 is the roots: 16 see single root or bifurcation or 2nd see trifurcation: root will give it away, if fused and small distally oriented than most probably a 3rd but if have 3 distinct grooves, good trfurcaiton not as flared 1st but distinction between them then probably a second - From this info, 15 or 16 correct