Mandibular Premolars Dental Health Proper Tooth Contours = Healthy Occlusion (Function) & Periodontal Health

Mandibular Premolars

Mandibular Premolars Mandibular 1st Premolars / Mandibular 2nd Premolars General Characteristics Development Appearance Buccal view Lingual view Mesial view Distal view Occlusal view Axial inclination Root and Pulp Space

Mandibular Premolars

Mandibular First Premolar

Mandibular First Premolar General Characteristics Buccal cusp is long and sharp BL dimensions similar to canine Occlusal surface slopes lingually Proximal view resembles a canine

Mandibular First Premolar Development First Calcification: 1.75-2 Yrs Enamel Completed: 5-6 Yrs Eruption: 10-12 Yrs Root Completed : 12-13 Yrs 4 Lobes

Mandibular First Premolar Buccal View Well developed middle labial lobe (buccal cusp ridge) Mesial cuspal ridge shorter than distal cuspal ridge General shape of trapezoid CEJ shows little curvature Proximals are flat at cervical and convex at proximal contact areas

Mandibular First Premolar Buccal View (continued) Distal is slightly more rounded Cusp tip is positioned to mesial Proximal contacts are located in occlusal 1/3**

Mandibular First Premolar Lingual View Lingual cusp very small (type trait) Cervical slope of occlusal surface Concave areas above CEJ mesial and distal Has mesiolingual developmental groove and strong transverse ridge

Mandibular First Premolar Mesial View Crown outline is rhomboid Like all mandibular posterior teeth Buccal cusp tip over center of root Buccal height of contour in gingival 1/3** Lingual height of contour in middle 1/3** CEJ has only a slight curvature Mesial marginal ridge is lower than distal marginal ridge

Mandibular 1st Premolar Distal View Distal marginal ridge is higher than mesial marginal ridge No developmental groove Buccolingual concavity above CEJ CEJ less curvature than mesial

Mandibular 1st Premolar Occlusal View Diamond-shaped Prominent buccal ridge Mesio- and distobuccal line angles are prominent Broad proximal contact areas Small lingual cusp

Mandibular First Premolar Occlusal View (cont.) Highly developed marginal ridges Mesial and distal fossae are present, usually with pits (“snake eyes”) Mesiolingual developmental groove (type trait) Much variation Strong transverse ridge

Mandibular First Premolar Axial Inclination Root inclination to lingual 9° Root inclination to distal = 6°

Mandibular First Premolar Occlusion Mandibular 1st premolar occludes with the maxillary canine and maxillary 1st premolar

Mandibular First Premolar Roots and Pulp Space Usually has 1 root; resembles canine root (oval shape) Root may have longitudinal groove Pulp chamber follows external form Usually one canal

Mandibular Second Premolar

Mandibular Second Premolar

Mandibular Second Premolar General Characteristics Differs in occlusal design, especially the lingual cusp(s) Larger root than mandibular 1st premolar

Mandibular Second Premolar Development 1s Calcification: 2.25-2.5 Yrs Enamel Completed: 6-7 Yrs Eruption: 11-12 Yrs Root Completed: 13-14 Yrs

Mandibular Second Premolar Buccal View Shorter buccal cusp Similar to first premolar: mesial and distal cusp ridges are not as sharp

Mandibular Second Premolar Lingual View Prominent lingual cusp(s) Lingual cusp(s) shorter than buccal but wider and taller than lingual cusp of 1st premolar Flat emergence angle Lingual groove

Mandibular Second Premolar Mesial View Crown and root wider than 1st premolar Larger lingual lobe development May be 5 lobes Marginal ridges perpendicular to long axis of tooth No mesiolingual developmental groove

Mandibular Second Premolar Distal View Crown is Angled Lingually to Long Axis: True of all Posterior Teeth(Maxillary and Mandibular) Lower Distal Marginal Ridge Than Marginal Ridge of Mesial

Mandibular Second Premolar Occlusal View 3 Cusps(“Y” outline) 2 Cusps(“H” outline) 2 Cusps(“U” outline) #29

Mandibular Second Premolar Occlusal View: “Y” configuration Square outline Central fossae 3 triangular ridges Developmental grooves(mesial, distal, lingual, “Y”) Triangular fossae(mesial, distal) #20

Mandibular Second Premolar Occlusal View: “H” Configuration Rounded outline Some lingual convergence Rounded distolingual line angles One lingual cusp Central developmental groove Mesial and distal fossae

Mandibular Second Premolar Occlusal View: “U” Configuration More rounded Very round line angles Central developmental groove Mesial and distal fossae

Mandibular Second Premolar Axial Inclination Root inclination to facial = 9° Root inclination to distal = 9°

Mandibular Second Premolar Occlusion The mandibular 2nd premolar occludes with the maxillary 1st premolar and the maxillary 2nd premolar

Mandibular Second Premolar Root and Pulp Space Larger root Oval in cross-section Root apex may deviate distally Pulp cavity usually has two pulp horns and one canal Canal is wider faciolingually