Dental Anatomy Past Paper PDF

9 v2 Teejan Lajneh Wisdom Aseel Sharaireh  MANDIBULAR MOLARS Introduction: o Most posterior teeth in the back of a mammal’s mouth used for the grinding of the food. o Unique in their design than any other tooth in the oral cavity. o 12 permanent mo...

9 v2 Teejan Lajneh Wisdom Aseel Sharaireh  MANDIBULAR MOLARS Introduction: o Most posterior teeth in the back of a mammal’s mouth used for the grinding of the food. o Unique in their design than any other tooth in the oral cavity. o 12 permanent molars, 3 per quadrant. o 8 deciduous molar, 2 per quadrant. o They are described as “strange or primitive “, because they kind of don’t look like the other teeth, they have their own anatomical specification that makes them quite strange to the rest of the teeth. o Man. molars are the largest, strongest teeth because of their crown bulk size and root anchorage in bone. (multiple roots) o They are accessional and non-succedaneous (They aren’t following the shedding of primary teeth, but they actually robbed on their own.) ▪︎ The largest occlusal surfaces of any of the Teeth mesio-distally ▪︎ Four to five major cusps. ▪︎ Lower permanent molars always have two Lingual cusps and two roots (mesial & Distal). The mandibular molars in the notation system:  The 7 primary functions of the teeth are for: Mastication/Swallowing/Speech/Expressions/Psychologic/Aesthetics/ Cranio-mandibular stabilization (the most important role for mandibular and maxillary molars) Helpful video: https://youtu.be/wBVax9JWS8U 1- Masticatory: -Molars are chewing teeth; they mainly crush and grind the food and they perform the major portion of the work in the mastication and comminution of food. Remember: lower jaw/mandible is mobile upper jaw/maxilla is immobile 2-Aesthetics: -In most people, mandibular molars can be seen during laughing and speaking. Having them missing or decayed decreases the aesthetic appearance of the smile. 3-Occlusal: -The bulky size and the strong multiple roots anchor these teeth in the jaws and support the muscles of mastication. The preservation of mandibular molars preserves the alveolar bone (the bone that surrounds the teeth) If molars in the mandible are lost, alveolar bone in their place will be resorbed and is technically difficult to reconstruct. The conservation of mandibular molars conserves the vertical dimension of the jaws and also contributes to the overall facial dimensions.  When they are lost, maxillary molars are likely to over-erupt in an attempt to compensate the loss of facial dimension. Which causes a whole other problem → unpleasant sounds. Severe Loss of the alveolar bone on Over eruption to the alveolar rim, that's caused due to maxillary molars the loss of socket bone which is very difficult to reconstruct once its lost. The tongue protruding to that area covering it. That will create sounds that aren't pleasant when the person speaks ▪ Morphology of Mandibular Molars: 1st Molar 2nd Molar 3rd Molar Mandibular molars (similar to maxillary molars) show progressive reduction in size when moving posteriorly. Mesio-distal dimension is larger than the Bucco-lingual dimension. They have largest mesio-distal dimension compared to all teeth! (Opposite to first molars of maxilla which have large labio-lingual dimension) 1st molar is the largest & shows the least morphological variation. 3rd molar is the smallest, most confined occlusal table & shows the most morphological variation! The fifth DISTAL CUSP is present in the first molar only. - types: could be a replica of the first molar (5 cusps) or a replica of the 2nd molar (4 cusps) The root portions are shorter than the other mandibular teeth, but the Combined measurements of the multiple roots, with theirbroad bifurcated root trunks, result in superior anchorage and greater efficiency & more surface area compared to other teeth. The sum of the combined mesio-distal measurements of mandibular molars is equal to or greater than the combined mesiodistal measurements of all the teeth anterior and premolars! ‫ببين معنا بوضوح في حال اخرجنا االسنان من الجو‬ Mesiodistally ‫وصفيناهم وحسبنا مجموع ال‬ ▪ Mandibular First Molar 5 developed functional Cusps (MB/ ML/ DL/ DB) and the Distal cusp. Distal cusp is over the buccal side, and its named after its location. The 2 lingual cusps are almost of equal size. With the size differences above the tooth has a lingual inclination Size order : Mesio-buccal cusp > mesio-lingual cusp > disto-lingual > disto-buccal > distal cusp The first tooth to erupt normally at around 6 yrs of age Early decay/Most decayed tooth in the oral cavity -especially in the proximal side-, (due to the fact erupted at a very early age and the bad oral habits of the children and the bad diet, thus those teeth can be lost at an early age)  Buccal Lingual WATCH THIS VIDEO FOR MORE UNDERSTANDING: https://youtu.be/kF_CSqVuYI8 Distal Mesial Occlusal ▪ Occlusal View: MESIAL MARGINAL RIDGE is longer & more Prominent than the DISTAL MARGINAL RIDGE Each cusp has a triangular ridge. NO transverse ridge in this tooth ○ One Major Fossa: Central Fossa ○ 4 Developmental grooves: Mesio-buccal groove Disto-buccal groove Central groove Lingual groove ○ Central Pit The groove pattern is often described as Y-shaped found in lower teeth. ○ Mesial & Distal triangular fossae; minor fossae: Mesial triangular fossa: Distal triangular fossa: M pit Distal pit MB & ML DB & DL supplementary grooves supplementary grooves Buccal View: o The mesio-buccal and disto-buccal cusps dominate the facial outline (80%) and are of almost equal height. o Disto-buccal developmental groove is apparent from this aspect, extends 2 thirds of the crown Hight. o Mesio-buccal developmental groov separates MB and DB cusps and terminates halfway the crown height in the BUCCAL PIT (usually found decayed). o Distal cusp is the smallest it can be partially seen from this aspect (20% of outline) o Cervical ridge passes around the buccal cusp (arch trait) o The two roots are widely separated. o The bifurcation between the Mesial and distal roots starts at the end of the root trunk on the middle of cervical third. The root trunk is short as seen in picture. o Distal bend in mesial root and distal projection of dorsal root. ○ Mesial contact area: Junction of middle and occlusal thirds ○ Distal contact areas: cervical to the junction of middle and occlusal thirds.  Lingual view: o 2 lingual cusps and a small proportion of distal cusp are seen from this aspect. o Lingual profile is narrower than the buccal profile. o Lingual groove separates the 2 lingual cusps which are of similar proportions. o Shallow vertical depression from cervical line to 2/3 of the root length. Mesial View: o Mesio-lingual cusp is slightly higher and sharper than the mesio- buccal cusp. o Proximal root concavity on the root surface. o Mesial marginal groove is apparent from mesial aspect. o Mesial marginal ridge is crossed by the mesial marginal groove. o Mesial root is broad Bucco-lingually and has a blunt end. o Buccal Maximum curvature (HOC): junction of middle and cervical thirds. o Lingual maximum curvature (HOC): middle of Middle 3rd Distal View: o All 5 cusps can be seen from this aspect o Cervical line on this side is nearly straight (0 mm). o Disto-buccal groove is apparent o the distal root is also broad Bucco-lingually but narrower than the mesial root, it also has a blunt apex. o the broadness in root surface enhances the anchorage & increases of the surface area for periodontal attachment.  Pulp Morphology: In a cross sectional view at cervix: o 3 canals with 3 canal orifices o The shape of access cavity is triangular with head of triangle towards the distal marginal ridge and the base towards the mesial o Distal canal the broadest. o ML and MB canals are higher and narrower than the distal canal. o Sometimes u might find 2 canals in distal root. o The head of the triangle is towards the distal side and then the base of the triangle is in the mesial. In a mesio-distal cross sectional view: o 2 horns (Distal horn and the mesio-buccal or the mesio-lingual horn) o Narrow canals In a Bucco-lingual cross sectional view : o 2 horns o Large Distal canal o 2 narrow canals in M root Access cavity of a first molar, watch this video: https://youtu.be/kF_CSqVuYI8  Mandibular Second Molar Generally it is similar to maxillary first molar with some differences in each aspect as following.. Occlusal View : o It has the characteristic “HOT CROSS BUN” occlusal view. (English cake) o NARROWER crown mesio- distally when compared to the fist molar. Crown is SHORTER and SMALLER in all dimensions (HOWEVER the mesio-distal width of the crown for molars is still higher than all other teeth in the oral cavity) o NO DISTAL CUSP. The tooth has 4 cusps: Mesio- lingual, Mesio-buccal, Disto-buccal, and Disto-lingual. o THE MESIAL CUSPS ARE LARGER THAN THE DISTAL CUSPS and this is how to distinguish the left from the right. (It is general rule in all teeth the mesial side always bigger than the Distal side expect for the maxillary first premolar ) o STRAIGHT MARGINAL RIDGES (square appearance) o MORE NUMEROUS SUPPLEMENTARY GROOVE.  Buccal View: o Similar to the first molar (except that no distal cusp) o Mesio -buccal developmental groove. separates MB and DB cusps and terminates halfway the crown height in the BUCCAL PIT (it can found decayed ). o The roots are slightly closer to each other (unlike the first mandibular molar ) and both distally inclined. o Mesial contact area: Cervical to the junction of middle and occlusal third o Distal contact area: Centered just below the marginal ridge Lingual view: o Similar to the first molar o Two lingual cusps separated by a groove with little M D proximal show. o Can't see any of buccal side Mesial View: o The mesial profile resembles that of the first molar. o Root is narrower BL with sharp apex (compared to the first mandibular molar). o Groove crossing through  Distal View: o No distal fifth cusp. o Distal root is much narrower than the mesial root and also has a pointed apex. o you can see all 4 cusps because Of the distal inclination. Pulp Morphology: o Similar to morphology and access cavity of mandibular first molar. o mesial root sometimes only has one canal instead of two. o The possibility of a C-shaped canal/pulp system is highest in this tooth and mandibular third molar (found where the two canal join together) Bucco-lingual Mesio-Distal Mandibular Third Molar o Mandibular (and maxillary) third molars show more developmental Variation than any other permanent tooth. o They are also frequently Congenitally missing (without any reasons some people don’t have Them). o Mandibular third molars vary considerably in size shape and Position and (sometimes they don’t follow any rule compared to Adjacent teeth). Sometimes they resemble the adjacent second Molar with four cusps, and hot cross buns shape or to the first Mandibular molar with five cusps.  Occlusal View : o FOUR OR FIVE cusp version of the tooth are present. This surface can be a good copy of the first or second molar, or poorly developed with many accessory grooves. o The occlusal surface is CONSTRICTED, with many grooves that are often numerous and short giving a crenulated appearance. o MESIAL half is WIDER Bucco-lingually then the distal half.( similar to First and second molar) Buccal View: o The crown is shorter in all dimensions and rounded (bulbous) in all different angles. o Convexity in all different areas. o Two roots are present, they are shorter but commonly found fused, they are very close to each other but sometimes they are completely fused (in one big massive bulbous root appearance ). o Roots shows a distal inclination, the trunk is almost halfway throw the root length. o Mesial contact area: Centered just Below the marginal ridge just Cervical to the junction between the middle and Occlusal thirds. o Technically, the mesial surface is the only 'proximal' surface. The distal Surface does not contact another tooth because it’s the last tooth.  Mesial View : o Similar to the 1st and 2nd molars with a more rounded outline o Distance between cusp tips on the mesial side is shorter (because of constricted occlusal table) Distal View : o The tooth is distally inclined therefore almost the entire of buccal profile is visible. o Distal root is the narrowest BL & shortest of all mandibular molars. Lingual View (Compared to first and second mandibular molars): o The crown is shorter and more rounded (bulbous). o Lingual cusps are not as sharp as first and second mandibular molars. o There is a little pit of groove and sometimes the lingual groove is not apparent Pulp Morphology: o Also similar to morphology and access cavity of mandibular first and second molars but the mesial root sometimes only has one canal instead of two. There is a possibility of a C-shaped canal where all root canal join together.  Occlusion: o In a typical Class I occlusal relationship: Static: maximum Inter-cuspation during centric occlusion 1. Mandibular 1st molar is ½ tooth mesial to the Maxillary 1st molar. 2. Mandibular 2nd molar is ½ tooth mesial to the Maxillary 2nd molar. o Mesio-buccal cusp of mandibular 1st molar occludes in the mesial triangular fossa of maxillary 1st molar. o Disto-buccal cusp of mandibular 1st molar occludes in the central fossa of maxillary 1st molar. o Mesio-buccal cusp of mandibular 2nd molar occludes in the mesial triangular fossa of maxillary 2nd molar. o Disto-buccal cusp of mandibular 2nd molar occludes in the central fossa of maxillary 2nd molar.  ‫)‪Watch this video: https://youtu.be/m38jMVYvFCQ :‬‬ ‫تمت كتابة هذا الشيت صدقة جارية عن روح والدة زميلنا عمرو رائد من دفعة تيجان‬ ‫دعواتكم لها بالرحمة والمغفرة‬ ‫‪Thank you‬‬