20.Permanent Maxillary Molars 3.pdf

Permanent maxillary molars Dr. Sandeep Gupta Assistant Professor Learning Objectives Generals of Molars Anatomy of Maxillary Molars Generals of Molars General Description Of Molars There are 12 permanent molars First, second and third on each side, both on the upper and lower arch Under universal nu...

Permanent maxillary molars Dr. Sandeep Gupta Assistant Professor Learning Objectives Generals of Molars Anatomy of Maxillary Molars Generals of Molars General Description Of Molars There are 12 permanent molars First, second and third on each side, both on the upper and lower arch Under universal numbering system they are 1,2,3,14,15,16,17,18,19,30,31,32 General Description Of Molars The first molars are centered in the arch anteroposteriorly This is one reason their loss is so devastating to arch continuity They are the largest and strongest teeth in the arch General Description Of Molars Can be congenitally missing Frequently, one or more of the third molars are congenitally missing This occurs in nearly 20% of the population Function Of Molars Play a major role in the mastication of food (chewing and grinding) Lost of first molar can result in more than 80mm of chewing surface gone Function Of Molars Important in maintaining vertical dimension of the face Important in maintaining continuity within dental arches, thus keeping other teeth in alignment Function in esthetics by keeping the cheeks full and keeping chin proper distance from the nose Class Traits Of Molars Crown Size And Shape – Have occlusal surfaces with three to five cusps – Have broader occlusal surfaces than other teeth Class Traits Of Molars Crown Size And Shape – Crowns of molars are wider mesiodistally Are shorter occlusocervically than other teeth Class Traits Of Molars Taper From Buccal To Lingual – Molar crowns taper to the lingual (i.e. crown is narrower on the lingual surface than the buccal surface) – Exception may be maxillary first molars with large lingual cusps (may taper toward the buccal) Class Traits Of Molars M Taper To The Distal – From an occlusal view all molar crowns taper distally D Class Traits Of Molars Contact Areas – Mesial: At or near the junction of the occlusal and middle thirds – Distal: Middle third Arch Traits Of Molars Crown Shape From Occlusal Maxillary – square /parallelogram – B-L>M-D Mandibular – rectangular/pentagonal – M-D>B-L Arch Traits Of Molars Number and Relative Size of Cusps DB DL MB ML Maxillary: 4-5 Cusps – Crown centered over roots – ML cusp: Largest and longest; connects to DB cusp by the Oblique Ridge – ML>MB> DB>DL Arch Traits Of Molars Maxillary Cusp of Carabelli: If present, is the fifth and smallest cusp Usually on lingual of ML cusp of maxillary first molars Arch Traits Of Molars Number and Relative Size of Cups Mandibular: 4-5 Cusps – ML and DL cusps are nearly equal in size (in contrast to maxillary molars) – Distal Cusp is minor fifth cusp, found on the first and sometimes third molars Arch Traits Of Molars B Mandibular Tilt – All mandibular teeth, including molars, tilt lingually when viewed from mesial or distal (this is not apparent on maxillary molars) – Crowns tilt distally relative to the long axis of the root L Arch Traits Of Molars Maxillary Roots – MB, DB, and Palatal roots – Roots are nearly twice as long as the crown – Relative length: Palatal>MB>DB Palatal DB MB Arch Traits Of Molars Maxillary Roots – Roots converge into a broad cervical root base called the Root Trunk Root Trunk Arch Traits Of Molars Mandibular Roots – Two Roots (Mesial and Distal) – Mesial root is usually slightly longer than distal root – Mandibular root trunks are shorter than maxillary root trunks, especially on first molars Anatomy of Maxillary Molars Type Traits of Maxillary 1st and 2nd Molars Relative Size – Second molar is smaller than the first molar in the same mouth, especially M-D – 1st Molar is broader than the 2nd Molar – 2nd Molar crown is often tipped distally on the root trunk Type Traits of Maxillary 1st and 2nd Molars Buccal Groove – Lies between buccal cusps and extends on the buccal surface to the middle third of the crown – Pit is sometimes present at the end of the groove that can be the site of caries Type Traits of Maxillary 1st and 2nd Molars Proximal Contacts Same as for all molars: – Mesial: Junction of occlusal and middle thirds – Distal: Middle third Mesial Type Traits of Maxillary 1st and 2nd Molars Outline Shape – The crown appears to tilt distally at the cervix – This, coupled with a short distobuccal cusp makes the crown appear shorter on the distal than the mesial Type Traits of Maxillary 1st and 2nd Molars Roots – Are attached to a root trunk (longer in second molars) at the cervical line – Apical to the root trunk there is a split into three roots – Furcation usually located at the junction of the cervical and middle thirds of the roots Type Traits of Maxillary 1st and 2nd Molars Roots – Three roots splitting of the root trunk is called a trifurcation 1st Maxillary First Molar Roots 2nd Much variation in the shapes of roots The MB and DB roots are often bent in such a way as to resemble the handles of a pair of pliers This is a contrast to second molars which have MB and DB roots nearly parallel Maxillary First Molar Roots The MB and DB roots often curve distally The apical third of the MB root may curve distally enough to put its apex distal to the buccal groove Lingual Aspect Of Maxillary Molars Crown - Relative Size and Taper – Due to the prominent DL cusp, crown may be as wide or wider on the lingual for the first molar – This is not as likely on the second molar 1st Lingual Aspect Of Maxillary Molars 2nd The crown of the second molar usually appears smaller than the first molar This is due mainly to the smaller or nonexistent DL cusp Number And Description Of Lingual Cusps - First Molar Two well defined cusps, ML and DL ML is usually the highest and largest of all cusps on any maxillary molar Often a fifth cusp, the cusp of Carabelli, which varies greatly in size and development 1st Number And Description Of Lingual Cusps - Second Molar There are two types of maxillary second molars based on number of cusps, 4 or 3 On the four-cusp second molar there is a ML and DL cusp On the three-cusp second molar the DL cusp is missing Roots Of First Molars From The Lingual Depression On first molars the palatal root is the third longest of any maxillary tooth (after canine and second premolar) Tapers apically to a blunt or rounded apex There is usually a depression on the lingual aspect of the palatal root Roots Of Second Molars From The Lingual Note Distal Bend The lingual (palatal) root is as long as the lingual root of the first molar The buccal roots bend towards the distal and are more parallel Proximal Aspect Of First Molars Cusps 1 23 – From the mesial, the crown appears broad faciolingually – Two or three cusps can be seen from the mesial (MB, ML, and Cusp of Carabelli) – Distal cusps are shorter and generally not seen from the mesial Proximal Aspect Of First Molars Mesial marginal ridge is more occlusal than distal, thus very little of the occlusal table can be seen from mesial There is considerable narrowing of the occlusal surface from crest of curvature, resulting in a narrow occlusal table Distal Proximal Aspect Of First Molars From the distal, four cusps are visible (may also see Cusp of Carabelli) Mesial Proximal Aspect Of Second Molars Distal From the mesial and distal aspect, looks much like the first molar, but no cusp of Carabelli is present DL cusp is absent on more than one third of these teeth Crest Of Curvature L On the buccal is located in the cervical third On the lingual (palatal) in the middle third B 1st Distal Taper Narrower To Distal 2nd Distal * On both first and second molars, the crown is narrower buccolingually on the distal than the mesial 1st Mesial Marginal Ridges 2nd Mesial On both first and second molars the mesial marginal ridge is concave and more occlusally located than the distal marginal ridge Tubercules If present are usually found on the mesial marginal ridge of first molars (rarely found on 2nd molars or distal marginal ridge of first molars) 1st Mesial 1st Mesial Marginal Ridge Grooves 2nd Mesial Marginal ridge grooves are more common on the mesial than the distal More common on first molars than second molars Cervical Line 1st Distal 1st Mesial The mesial cervical line has a slight occlusal curvature There is slightly less curvature on the distal than the mesial Proximal Contacts 1st Distal 1st Mesial The mesial contact area is a the junction of the middle and occlusal thirds The distal contact area is in the middle third Roots Of Maxillary Molars From The Proximal MB From the mesial view the MB root is broad buccolingually and is shorter than the lingual root The MB root obscures the view of the DB root Apex of the MB root is in line with the MB cusp tip Roots Of Maxillary Molars From The Proximal The lingual root is the longest and often banana shaped On first molars extends well beyond the crown lingually Usually curved buccolingually L Distal Roots Of Maxillary Molars From The Proximal From the distal, the DB root is shorter and narrower than the MB root Can see the outline of both roots from the distal Roots Of Maxillary Molars From The Proximal 1st Mesial 2nd Mesial On second molars roots are much less spread apart Lingual roots is also straighter, usually not extending past confines of the crown Occlusal Aspect Of First Molars The contour of first molars is not square, but gives that impression when compared to other teeth It is roughly a parallelogram Occlusal Aspect Of Second Molars The second molar is wider buccolingually than mesiodistally and tapers to the lingual Much variation in second molar due to size and location of DL cusp Occlusal Aspect Of Second Molars The four-cusp version of the second molar is less square in appearance 2 3 4 1 5 Number And Size Of Cusps 2 3 4 1 Generally there are four cusps First molar possess a fifth cusp 70% of the time Second molar may be missing the DL cusp Oblique Ridge Unique To Maxillary Molars The oblique ridge connects the DB cusp with the ML cusp It is present in second molars, but smaller than the oblique ridge of first molars Fossae On Four-Cusp Molars There are generally four fossae on four-cusp molars 1) Central Fossa 2) Mesial Triangular Fossa 3) Distal Triangular Fossa 4) Distal Fossa 3 1 4 2 Grooves On Four-Cusp Molars Buccal Groove Distal Oblique Groove Central Groove Transverse Groove Of The Oblique Ridge Lingual Groove Fifth Cusp Groove Fossae And Grooves On Three-Cusp Molars The distal fossae and both the distal oblique and lingual grooves are absent Maxillary Third Molars Maxillary Third Molars General description difficult due to great variation Roots and crown shorter than first or second molar Crown often possess more supplemental grooves May possess three, four or five cusps Mesial Roots Of Maxillary Third Molars Buccal Possess three roots, but more often they are fused for most of their length Roots are shorter than those of first and second molar Thank You