Dental Anatomy_ Premolars.pdf

Dental Anatomy: Premolars Max 1st Premolar Max 2nd Premolar Mand 1st Premolar Mand 2nd Premolar First Evidence of Calcification 18-21 mon 24-30 mon 21-24 mon 27-30 mon Crown Complete 5-6 yrs Biggest premolar crown Eruption 10-11 yrs 6-7 yrs 10-12 yrs 11-12 yrs Root Complete 2-3 yrs a...

Dental Anatomy: Premolars Max 1st Premolar Max 2nd Premolar Mand 1st Premolar Mand 2nd Premolar First Evidence of Calcification 18-21 mon 24-30 mon 21-24 mon 27-30 mon Crown Complete 5-6 yrs Biggest premolar crown Eruption 10-11 yrs 6-7 yrs 10-12 yrs 11-12 yrs Root Complete 2-3 yrs after eruption Mesial Proximal Contact / HOC Occlusal-middle ⅓ Distal Proximal Contact / HOC Occlusal View Proximal View Middle ⅓ Hexagon Occlusal-middle ⅓ Ovoid Diamond Trapezoid Rhomboid Buccal View Pentagon Facial HOC Cervical ⅓ Lingual HOC Middle ⅓ Dimensions Cusps Square Max premolars are larger buccal-lingually than mesial-distally Mand premolars similar buccal-lingually and mesial-distally Max 1st premolar larger facial-lingually than Max 2nd Mand 2nd premolar larger buccal-lingually than Mand 1st 2 cusps, nearly same size Y-Configuration H-Configuration 2 cusps U-Configuration 2 or 3 cusps Sluiceway/Spillway: supplemental grooves → escape paths for food to squeeze out Pre-molar Facts - - - Contact areas for premolars and especially molars become more level with each other Common in every premolar cusp: - Cusp tip - Cuspal ridge - Triangular ridge: from cusp to center groove of tooth - Central groove: divides the cusps Transverse ridge: when two triangular ridges are directly opposite of each other, and meet straight bucco-lingually Oblique ridge: when two triangular ridges come and meet (not directly opposite of each other) and are angled bucco-lingually If 2 cusps (1 buccal and 1 lingual): - Transverse ridge - 2 fossae - mesial, distal If 3 cusps (1 buccal, 2 lingual) - 2 Oblique ridges - Mesial lingual cusp > distal lingual cusp - Buccal cusp centered mesio-distally - 3 fossae - mesial, central, distal