Maxillary Molars Anatomy, Morphology, and Function PDF

MAXILLARY MOLARS ANATOMY, MORPHOLOGY AND FUNCTION DR. MAIS M ODAH BDS, MCLINDENT IN PROSTHODONTICS PALESTINIAN BOARD LECTURE OUTLINE FUNCTION AND ANATOMICAL INTRODUCTION MORPHOLOGY OF LANDMARKS...

MAXILLARY MOLARS ANATOMY, MORPHOLOGY AND FUNCTION DR. MAIS M ODAH BDS, MCLINDENT IN PROSTHODONTICS PALESTINIAN BOARD LECTURE OUTLINE FUNCTION AND ANATOMICAL INTRODUCTION MORPHOLOGY OF LANDMARKS Maxillary MOLARS OCCLUSION CHRONOLOGY  MOLARS By definition; molars are the most posterior teeth at the back of a mammal's mouth and are used for the grinding of food. Three molars per quadrant in the permanent set of teeth (12 permenant molars), and two molars per quadrant in the deciduous dentition (8 deciduous).  MOLARS Unique in their design than any other tooth in the oral cavity The largest and strongest teeth in the mouth by virtue of their crown bulk size and root anchorage in bone - The largest occlusal surfaces of any of the teeth - Three to five major cusps. - Lower permanent molars always have two lingual cusps. Upper permanent molars always have two buccal cusps. - Lower molars have two roots. Upper molars have three roots.  MOLARS Unprecedented/ Accessional/ nonsuccedaneous They are NOT preceded by primary teeth. Permanent molars are accessional teeth without primary predecessors In contrast permanent incisors, canines and premolars are succedaneous (successional teeth).  MOLARS Functions: Aesthetic Masticatory Occlusal  FUNCTIONS OF MOLARS The primary functions of the teeth are for: Mastication/ Swallowing/ Speech/ Expressions /Psychologic Aesthetics/ Cranio-mandibular stabilization. Masticatory; Molar 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  FUNCTIONS OF MOLARS The primary functions of the teeth are for: Mastication/ Swallowing/ Speech/ Expressions /Psychologic Aesthetics/ Cranio-mandibular stabilization. Aesthetics are not restricted to the six anterior maxillary teeth and premolars. In large smiles, THE FIRST MOLAR CAN BE SEEN AND HIGHLY CONTRIBUTE TO AN AESTHETIC SMILE DESIGN. In most people, during laughing, second molars can be seen as well!  FUNCTIONS OF MOLARS The primary functions of the teeth are for: Mastication/ Swallowing/ Speech/ Expressions /Psychologic Aesthetics/ Cranio-mandibular stabilization. Occlusal: the bulky size and the strong multiple roots anchor these teeth in the jaws and support the muscles of mastication BITE FORCE: in an average homo sapiens female the bite force on second premolars can reach up to 2300N (equals around 234.5 KG!!!) (Reference: https://royalsocietypublishing.org/doi/10.1098/rspb.2010.0509) The preservation of VERTICAL DIMENSION of the jaws also contribute to the overall FACIAL DIMENSIONs and thus the overall facial aesthetics.  MAXILLARY MOLARS Ø 6 MOLARS IN THE MAXILLA Ø POSTERIOR TEETH Ø 3 OR MORE CUSPS: AT LEAST 2 BUCCAL CUSPS AND ONE OR MORE LINGUAL CUSPS Ø 3 ROOTS: 2 BUCCAL AND 1 PALATAL Ø POSITION: DISTAL TO SECOND PREMOLARS AND MESIAL TO NONE!  MAXILLARY MOLARS Disto-lingual cusp shrinks in size when going posteriorly to almost being missing in the 3rd molar Bucco-lingual dimension is larger the mesio-distal dimension 1st molar is the largest & shows the least morphological variation while 3rd molar is the smallest & shows the most morphological variation! OBLIQUE RIDGE: Mesio-lingual cusp to disto-buccal cusp  B MAXILLARY FIRST MOLAR Ø 4 developed functional cusps (MB/ DB/ MP/ DP) and 1 supplemental cusp called the “Cusp of D M Carabelli” or “Carabelli's tubercle” Ø Mesio lingual cusp is the largest Ø BUCCAL and Distal convergence! Ø Three roots P  MAXILLARY FIRST MOLARS OCCLUSAL VIEW: Mesial and distal B triangular fossae; minor fossae: M triangular fossa MESIAL MARGINAL RIDGE M pit is longer & more MB & ML D prominent than the supplementary DISTAL MARGINAL RIDGE M grooves D triangular fossa Distal pit Oblique ridge DB & DL supplementary grooves P MAXILLARY FIRST MOLARS OCCLUSAL VIEW: B Two distinct components: Two Major Fossae: TRIGON Central fossa - Bears MB, ML & DB cusps - Tricuspate triangle Central pit Buccal groove TALON D Distal groove - Bears DL cusp & D MR Central groove - Located DL to the tricuspate M Distal fossa triangle D pit - Well-developed in 1st molar DL groove or distal & undergoes reduction in size oblique which in 2nd & 3rd molars continues as the L groove P MAXILLARY FIRST MOLARS BUCCAL VIEW: The mesio-buccal and disto-buccal cusps dominate the facial outline. MB & DB cusps are of almost equal height. Mesio-buccal is wider than disto-buccal Buccal developmental groove separates MB and DB cusps and terminates halfway the crown height in the BUCCAL PIT. D M Mesio-lingual cusp is the largest it can be seen from this aspect MAXILLARY FIRST MOLARS BUCCAL VIEW: All three roots are visible. The buccal roots present a 'plier handle' appearance with the larger and longer lingual root centered between them. The bifurcation between the MB and DB roots starts at the end of the root trunk on the junction between Cervical & middle thirds. D Mesio-Buccal root is usually the smallest but it M has a curvature and might have two canals. LET’S TALK CLINICAL! The bifurcation between the MB and DB roots starts at junction between Cervical & middle thirds. à CLINICAL SIGNIFICANCE: periodontal disease reaching bifurcation: prognosis Mesio-Buccal root is usually the smallest but it has a curvature and might have two canals. à CLINICAL SIGNIFICANCE: endodontic treatment of this tooth needs proper inspection for the second Mesio-Buccal canal (MB2) MAXILLARY 1ST MOLAR BUCCAL VIEW: Mesial contact area: 3/4 the distance from cervical line to mesial marginal ridge Distal contact areas: 3/5 the distance from cervical line to distal marginal ridge  MAXILLARY FIRST MOLARS LINGUAL VIEW: Unequal sizes of the two cusps. The fifth cusp of the supplemental Cusp of Carabelli” can be seen clearly on the ML cusp Disto-lingual groove separates the two lingual cusps Palatal root: - Tapered with blunt apex M D - Shallow vertical depression from cervical line to 2/3 of the root length MAXILLARY FIRST MOLARS MESIAL VIEW: Trapezoidal outline: with maximum bucco-palatal dimension is at the cervix of the crown Buccal Maximum curvature: middle of cervical 3rd then outline continues straight Palatal maximum curvature: middle of middle 3rd Palatal root is narrow & Banana-shaped it curves palatally then buccally at the apex Mesial contact point placed more to the buccal Mesial marginal ridge side is marked by several tubercles & supplementary grooves Cervical line is slightly curved towards the crown (1 mm) Deep developmental groove on the root surface on B P mesio-buccal root MAXILLARY FIRST MOLARS DISTAL VIEW: Buccal and palatal profiles are similar to in this view to the mesial side. Cervical line on this side is nearly straight (0 mm) Distal contact point lies in the centre (bucco- palatally) Distal marginal ridge rarely has tubercles, it is shorter & less prominent than mesial marginal ridge à You can see part of the occlusal surface. Disto-buccal root is the smallest in size P B MAXILLARY FIRST MOLARS PULP MORPHOLOGY: In a cross sectional view at cervix: 3-4 canals with 3-4 canal orifices The shape of access cavity is triangular with head of triangle towards the mesio-palatal cusp and the base towards the buccal. In a mesio-distal cross sectional view: 2 horns, MB is higher Large Pulp chamber (it has a roof & a floor) Buccal canals are narrow while palatal canal is usually wide MAXILLARY FIRST MOLARS PULP MORPHOLOGY: In a bucco-palatal cross sectional view: Pulp chamber is wider 2 horns of equal height Pulp morphology is complicated and variant between individuals P DB MB Micro computed tomography (micro-CT) scan of axial cross section of Maxillary first molar BOTH VIDEOS CREDIT GOES TO: STEPHEN SHEPHERD HTTPS://YOUTU.BE/ELGH_-OTKYS MAXILLARY SECOND MOLARS M al es io Similar to maxillary first molar generally but cc -b u differ in the followings: -b uc o ist ca Ø The disto-buccal cusp is not as well D l developed as in maxillary first molar. The disto palatal cusp is smaller. Ø The cusp of Carabelli is absent from this tooth. Ø The roots are of the same length as 1st molar and sometimes longer Ø The roots are slightly less divergent Ø The crown is shorter cervico-occlusally with amolst the same width bucco- Di al sto palatally when compared to maxillary lat -p a first molar -p al si o at Me al MAXILLARY SECOND MOLARS M l es a io cc -b -bu uc OCCLUSAL VIEW: ist o ca D l Ø NARROWER CROWN MESIODISTALLY WHEN COMPARED TO THE FIRST MOLAR Ø THE DISTO-PALATAL CUSP IS SMALLER IN THE 2ND MOLAR (SMALLER TALON). Ø DIFFERENCE IN THE SIZE OF CUSPS IS MORE EXAGGERATED: LARGEST TO SMALLEST: MESIOPALATAL, MESIOBUCCAL, DISTOBUCCAL, AND Di DISTOPALATAL. al sto lat -p Ø MORE VARIABLE PIT/GROOVE PATTERN -p a al si o at Ø MORE NUMEROUS SUPPLEMENTARY GROOVE Me al MAXILLARY SECOND MOLARS BUCCAL VIEW: The two buccal roots are nearly Similar to the first molar parallel and they are more straight compared to 1st molar. D M MAXILLARY SECOND MOLARS BUCCAL VIEW: Both Mesial and Distal contact points tend to be centred bucco- palatally below the marginal ridges. à Molars become shorter MAXILLARY SECOND MOLARS LINGUAL VIEW: Palatal root is narrower mesio- distally slightly distally inclined D M MAXILLARY SECOND MOLARS MESIAL VIEW: The crown is shorter than the first molar The palatal & mesio-buccal roots have less divergence and roots tend to remain within the crown profile. Buccal Maximum curvature: middle of cervical 3rd B Palatal maximum curvature: middle of P middle 3rd Mesial marginal ridge has less numerous tubercles compared to 1st molar. MAXILLARY SECOND MOLARS DISTAL VIEW: A greater portion of the occlusal aspect is visible from this aspect P B MAXILLARY SECOND MOLARS PULP MORPHOLOGY: Similar to morphology and access cavity of maxillary first molar but the second mesio-buccal canal (MB2) is less likely to be present MAXILLARY THIRD MOLARS M al es io Maxillary (and mandibular) third molars cc -b u show more developmental variation than -b uc o ist ca any other permanent tooth. They are also D l frequently congenitally missing. Ø Maxillary third molars vary considerably in size shape and position Ø Some third molars resemble the adjacent second molar; others may have many cusps, small 'cusplets', and many grooves. Ø The crown of this tooth is the smallest of the maxillary molars al Di t sto pala -p sio- al Me at al MAXILLARY THIRD MOLARS M l es a io cc -b -bu uc OCCLUSAL VIEW: ist o ca D l Ø THE OUTLINE OF THE OCCLUSAL SURFACE CAN BE DESCRIBED AS TRIANGULAR OR 'HEART-SHAPED.' Ø DIFFERENCE IN THE SIZE OF CUSPS IS EVEN MORE EXAGGERATED: LARGEST TO SMALLEST: MESIOPALATAL, MESIOBUCCAL AND DISTOBUCCAL DISTOPALATAL IS OF MINIMAL SIZE. Ø OBLIQUE RIDGE IS BARELY VISIBLE Di al sto lat -p Ø PIT/GROOVE PATTERN IS VARIABLE a -p al si o at Ø NUMEROUS SUPPLEMENTARY GROOVES Me al MAXILLARY THIRD MOLARS Two buccal roots are present, they BUCCAL VIEW: are shorter but in commonly found The crown: fused. - Shorter and smaller in all Roots shows a dimensions. slight distal - The mesial buccal cusp is inclination. larger than the distal buccal cusp. D M MAXILLARY THIRD MOLARS BUCCAL VIEW: Mesial contact point middle of crown is below the marginal ridges. Technically, the mesial surface is the only 'proximal' surface. The distal surface does not contact another tooth. MAXILLARY THIRD MOLARS LINGUAL VIEW: Either one large palatal cusp or two with poorly developed disto-palatal cusp and its poorly developed lingual groove. Palatal root is often fused to the two buccal roots. D M MAXILLARY THIRD MOLARS MESIAL VIEW: The rounded or bulbous outline. Crown profile is irregular Fused roots B P MAXILLARY THIRD MOLARS DISTAL VIEW: A greater portion of the occlusal aspect is visible from this aspect compared with 1st & 2nd maxillary molars P B MAXILLARY FIRST MOLARS PULP MORPHOLOGY: In a cross sectional view at cervix the pulp looks: Ovoid Narrow mesio-distally In a mesio-distal cross sectional view: Large mesiobuccal horn & small distobuccal horn MAXILLARY FIRST MOLARS PULP MORPHOLOGY: In a bucco-palatal cross sectional view: Mesiobuccal and palatal horns are of equal prominence Dental Press Journal of Orthodontics  OCCLUSION! In a typical Class I occlusal relationship: à Static: maximum Inter-cuspation during centric occlusion: q Maxillary 1st molar is ½ tooth distal to the Mandibular 1st molar q Maxillary 2nd molar is ½ tooth distal to the Mandibular 2nd molar  OCCLUSION In a typical Class I occlusal relationship: à Static: maximum Inter-cuspation during centric occlusion: q Mesio-palatal cusp of maxillary 1st molar occludes in the central fossa of mandibular 1st molar q Disto-palatal cusp of maxillary 1st molar occludes in the distal triangular fossa of mandibular 1st molar  OCCLUSION In a typical Class I occlusal relationship: à Static: maximum Inter-cuspation during centric occlusion: q Mesio-palatal cusp of maxillary 2nd molar occludes in the central fossa of mandibular 2nd molar q Disto-palatal cusp of maxillary 2nd molar occludes in the distal triangular fossa of mandibular 2nd molar  TOOTH CHRONOLOGY Maxillary 1st molar Maxillary 2nd molar Maxillary 3rd molar evidence of At birth 2-3.5 yrs 8-10 yrs. calcification: Enamel 3-4 yrs. 7-8 yrs 12-16 yrs. completed: Eruption 6-7 yrs. 11-13 yrs. 17-21 yrs. Root 9-10 yrs. 14-15 yrs. 18-25 yrs. completed:  THANK YOU https://youtu.be/NmM-plwepFY