hello dear friends welcome to dental education hub youtube channel today we are going to discuss the morphology of the deciduous maxillary first molar so what we are going to discuss in this short video lecture we are going to discuss the chronology or the timeline of development of the maxillary deciduous first molar we are going to discuss the number of this tooth in various truth-intension systems and we are also going to discuss the landmarks that are present on the deciduous maxillary first molar so please watch this video till the end so what is the timeline of development of the deciduous maxillary first molar the first evidence of calcification it begins when the child and the baby is 15 weeks in neutral the enamel it is completed by the age of six months the tooth it emerged into the oral cavity by the age of 16 months and the root it is completed by the age of two and a half years around the age of 10 years this tooth it is exfoliated and the tooth it is replaced by the maxillary first premolar or what is the alphabet that is used for this tooth in various root notation systems so in the maxillary first is smaller so this is the second molar and the alphabets they begin with a so for the first molar the number the alphabet is b for the right maxillary first molar and for the deciduous left first molar in the maxillary arch the alphabet is i now in the parliament notation system the alphabets they begin from the midline the alphabets that begin from the midline for both for the right and the left side the alphabets are the same the only difference is this symbol this symbol is used for the maxillary quadrant of the right side and this symbol is used for the maxillary quadrant of the left side so the alphabet is for the right maxillary first molar is d and for the deciduous left maxillary first molar also the alphabet is d the only difference is this symbol now in the fdi annotation system in the fdi annotation system for the right maxillary first smaller test to a smaller the number is 5 4 here the 5 and it indicates that it is a right quadrant of the maxillary arch and four indicate that it is the first deciduous molar similarly on the left side the number is six four here the six it indicates that it is a maxillary quadrant of the left side and four it indicates the tooth number now what are the distinguishing features or what are the important features of this tooth from the buccal aspect so from the buccal aspect the widest measurement is at the contact areas so the tooth it is wider measure distally at the contact areas where if the cervical portion of the crown mesodesk is the narrowest it's very narrow at the cervical area overall um unlike the permanent molars the buccal surface it is smooth and very less evidence of the developmental grooves are there on the buccal side there are three roots this is the mesial root this is the distal root and this is a lingual root sometime referred also referred as the palatal root so there are three roots mesial distal and lingual root so the roots they are cylinder and they are long and they are widely separated so you can see the roots they are widely separated they are long and there are cylinder in shape so among these three roots this is the distal root and the distal root it is shorter than the mesial roots now the division of these roots so the division of the roots that begin just below the cemento enamel junction so this portion is the root trunk so the root trunk in the deciduous dentition it is not well developed so the roots they immediately divide and the root trunk it immediately divides into three roots and then same for the mandibular arch while in the permanent dentition the root trunk is quite well developed now uh from the lingual aspect the crown it converge towards the lingual side so the mesio distal width the mesial distillate it is less on the lingual side so the part of the mesial side of the tooth and part of the distal side are visible from the lingual aspect this cusp is the mesial lingual cost so the mesial lingual casp is the most prominent cusp while the distilling will cause it is short and it is rounded sometimes the distilling will cause it is missing so in that case only three cusp type is present in which there is one lingual cusp and there are two buccal cask now among from the lingual aspect also the three roots they are visible mesial distal and lingual and among these three roots the lingual root is the largest larger one from the mesial aspect the mesial lingual cusp it is longer and sharper than the mesiobuccal cusp so mesiolingual cusp it is longer so this is the mesio-lingual cast so this cusp is larger and it is sharper than the mesiobuccal cusp this is the mesial marginal ridge now if you look at the buccal surface of the crown there is a pronounced convexity in this area this convexity is present on the buccal side at the cervical third of the crown so this is a cervical third of the crown are marked convexity is there this is the cervical line at the cement or enamel junction and the cervical line is show curvature towards the occlusal surface now the lingual root initially after the division from the root run the lingual root it extends lingually and very prominently it extend towards the lingual side lingual root then curve sharply in a buccal direction above the middle third so above the middle third it again it curves now it curves sharply towards the buccal side so from the distal side the crown it is it is narrow so the buccal lingual width of the crown it is narrow on the distal side so you can see part of the buccal aspect and the lingual aspect from the distal distal side so this cast is the disto buccal casp so that is to buccal cost it is long and sharp as compared to the disto lingual cusp which is small and rounded so in the background you can see the mesiolingual and the mesial buccal cusps as well [Music] this is the cervical line and the cervical line extend nearly straight from the buccal side towards the lingual side and the curvature it is very less if you compare it with the curvature of the mesial side that is present on the nasal side in addition to these the distal root and the lingual root the buccal surface and effects of the mesial buccal root it is also visible so the buccal surface and the apical area they are visible of the mesiobuccal root they are visible from the distal aspect from the occlusal aspect when you look at the occlusal aspect the crown it basically it converges towards the lingual side so the crown it basically it converge towards the we're still lingual side so the width compare the mesial distal width from the buccal side is more than the mesio-distal width from the lingual side crown it also in addition to the lingual convergence the crown it also converge on the distal side so the distal side the crown it is the dimensions it is less as compared to the dimensions the buccal lingual dimensions on the mesial side now this is the occlusal surface and this central area it contain a fossa and this fossa is known as the central fossa so central fossa is present somewhere over in this area so this area is the central fossa in addition to the central fossa there are some other fossils as well for example this fossa is the is the mesial triangular fossa a very small fossa is present in this area another triangular fossa and this is known as the the distal triangular fossa so this is the central fossa this is the mesial triangular fossa and this is the distal triangular fossa this is the central developmental groove central developmental groove that extends from the mesial triangular fossa to the distal triangular fossa from this central developmental groove many supplementary grooves they also arise from this central developmental groove so there are two ridges and and these are present at the margins so we call them as marginal ridges so this is the mesial marginal wedge which is thick and properly developed this is the distal marginal wedge and the distal marginal weight it is thin small and it is poorly developed thank you very much for watching this lecture of the deciduous maxillary first molar uh follow us on instagram for questions images and flash cards this is our instagram handle thank you very much and stay blessed