Dental Anatomy 3: Lobes, Cusps, Inclinations, & more

Occlusal Curvatures and axial positions 

• Curve of spee: 2d curvature = buccal cusp tips of premolars and molars posteriorly, curvature begins @ tip of canines and curves upwards from anterior → posterior 

  
  





• Max molar roots = inclined MESIALLY

  
  



• Mandi molar roots = inclined DISTALLY 

  
  





• Curve of Wilson: the medio-lateral curvature of the occlusal plane of posterior teeth → complements the paths of the condoles during mandible movement 

  
  





• Also 2d 

  
  



• Crowns of MANDI posterior teeth incline to the lingual (Lingual Lower)

  
  



• Crowns of MAX posterior teeth incline toward buccal (Buccal Upper) 

  
  



• Molars have greater inclination bc the curve  → deeper posterior 

  
  





• Sphere of Monson AKA compensating occlusal curvature = 3d sphere shaped curvature for occlusal plane Concave curve for mandi, convex for maxillary = combo of curve and spee and curve of Wilson

  
  

Axial position/Root inclination

• Axial position = the inclination of a tooth from vertical axis 

  
  





• Normally described in mesiodistal and faciolingual direction (but a combo of the two) = opposite of BULL

  
  



• Crown is normally inclined in the OPPOSITE direction = BULL

  
  

Crown surface form 

• From facial/lingual aspects ALL permanent teeth = rougly trapezoidal 

  
  

Tooth 

Shape of Crown

Info

Anterior

Tringular 

• Proximal view → triangular 

  
  



• Base = cervical 3rd

  
  



• Apex = incisal 3rd

  
  



• Apex = wedge in tearing, biting, and incising food

  
  

Max posteriors

Trapezoidal 

• Proximal view → trapezoidal 

  
  



• Base = cervical 

  
  



• Wedge → aids in distribution of forces during mastication and self-cleaning process

  
  

Mandi posteriors

Rhomboidal 

• Proximal → rhomboidal 

  
  



• Crowns = inclined toward the lingual  = proper interlocking of the Mandi and max posterior teeth during mastication 

  
  

Contact areas

• Increase in size with age = Abrasive contact in proximals broaden the area 

  
  





• Mesiodistal length of dental arches = get shorter = as teeth become narrower mesiodistally, they are moving closer to midline 

  
  





• Proper contact location = stabilizes dental arch and prevents food packing 

  
  



• Contact areas become more cervically located from anterior → posterior in each quad (basically just move down towards cervical 3rd from midline to molars) 

  
  



• Distal contact area normally = more cervical location than mesial contact 

  
  



• Relative size increases from anterior to posterior in each quad

  
  



• Posterior teeth → contact areas = normally located to the buccal of center in the faciolingual dimension 

  
  

Cervical Line: Curvatures

• CEJ = cervical line = line around the tooth where enamel and cementum meet 

  
  





• Separates anatomical crown and root → only visible when not covered by soft tissue

  
  



• It is stable (unlike gingival line → everchanging)

  
  





• Gingival line = gingival margin/crest → imaginary line which marks the level of termination of nonattached soft tissue surrounding the tooth 

  
  





• Separates the clinical crown and root → is always visible 

  
  





• Epithelial attachment = actual attachment of the soft tissue of the mouth to the tooth 

  
  





• Can be distinguished From the PDL 

  
  



• Connection for soft gingival tissue 

  
  



• PDL = attachment of the hard tissue (bone_ to the tooths root structure 

  
  



• Usually a sulcus between gingival Marin and epithelial attachment 

  
  

Cervical Line Countour Rules

• Cervical line normally curved (convex) or bulges TOWARD the apical on the → lingual and facial teeth surfaces

  
  



• CL is normally convex toward the incisal/occlusal on → the mesial and distal surfaces

  
  



• The amount (depth) of cervical line curvature on any tooth is normally GREATER on the MESIAL compared to distal 

  
  



• Cervical lines on adjacent prox. Surfaces of adj. teeth have → approx same depth of curvature

  
  



• Depth of curvature on all surfaces = greatest on → central incisors and decreases POSTERIORLY