Dental Anatomy: Morphology of Centrals & Incisors PDF

Dental Anatomy: Morphology of Centrals & Incisors l. Eruption of Anterior Incisors · First evidence of permanent tooth development: 3-4 months after birth o Exception: maxillary lateral incisor · How long it takes for crown to fully mature: 4-5 years · First anterior tooth to erupt: mandibular centr...

Dental Anatomy: Morphology of Centrals & Incisors l. Eruption of Anterior Incisors · First evidence of permanent tooth development: 3-4 months after birth o Exception: maxillary lateral incisor · How long it takes for crown to fully mature: 4-5 years · First anterior tooth to erupt: mandibular central incisor · How long it takes for root to fully mature: 2 years Maxillary central Maxillary lateral First evidence of calcification 3-4 months 10-12 months Crown completion (same) 4-5 years 4-5 years Eruption 7-8 years 8-9 years (1 year difference) Root completion 10 years 11 years (1 year difference) Maxillary canine is last tooth to erupt + complete its root development (13-15 years) Mandibular central Mandibular lateral First evidence of calcification (same 3-4 months 3-4 months Crown completion (same) 4-5 years 4-5 years Eruption 6-7 years 7-8 years (1 year difference) Root completion 9 years 10 years (1 year difference) Maxillary and mandibular centrals + mand laterals have first evidence of calcification at same time (3-4 months) Mandibular centrals are first to erupt, then maxillary centrals Maxillary and mandibular laterals follow after II. Proximal Contacts & Crown Outline Form Diastema – space found between teeth NOT THE SAME AS AN “OPEN CONTACT” Diastema is natural, “open contact” is a technical failure of a restoration Crown outline form Maxillary incisors: triangular Mandibular incisors: diamond Facial-incisal line angle is higher than lingual-incisal line angle Mamelons – tiny levations on the incisal surface on newly erupted incisors o Gives appearance of irregular edges o Gradually wears away over time making way for incisal edge formation Height of Contour Widest portion of the anatomical crown LO: Sequence the dates for eruption and tooth development for each tooth Maxillary Incisors First evidence of calcification Mandibular Incisors 3-4 mon Except max lat incisors: 10-12 mon - Last incisor to erupt Crown completion Eruption First to erupt: mand cen incisors 4-5 yrs Central: 7-8 yrs Central: 6-7 yrs Lateral: 8-9 yrs Lateral: 7-8 yrs Root Completion Avg 2 yrs after eruption LO: Define basic geometric shapes of each tooth and why they have specific shape Shapes help → bite, cut, tear Dimension Facts Incisal Lingual Proximal View Max Incisors View View trapezoid triangle Max Cen Incisor → largest inciso-cervical dimension among incisors triangle Max Lat Incisor → considerable amount of cervical ⅓ constriction among all incisors Mand Incisors Relatively similar in dimensions diamond Mand Cen Incisor → smallest perm tooth LO: Describe where the heights of contour (HOC) are for each tooth HOC: widest portion of anatomical crown 1. Hold tooth horizontally & drop imaginary line against given surface 2. Initial point of contact = HOC *All facial-lingual HOC of anteriors are cervical ⅓ *Proximal HOC is similar to proximal contact LO: Identify the locations of the proximal contacts for each tooth Proximal contacts Help preserve continuity of dentition Maintain healthy smile Determine shape of surrounding gingival tissues Add esthetic value Diastema natural space found between teeth Open contact technical failure of re-establishing a previously existing contact Max Cen Max Lat Max Canine Mand Cen Mand Lat Mand Canine Mesial Incisal ⅓ Incisal-Mid ⅓ Incisal ⅓ Incisal ⅓ Incisal ⅓ Distal Incisal-Mid ⅓ Mid ⅓ Incisal ⅓ Incisal ⅓ Mid ⅓ LO: Compare and contrast the set and arch traits of each tooth Max Cen Incisor - Facial View - Mesial-incisal edge: sharp, 90 deg - Mesial surface: convex - Distal-incisal edge: rounded - Distal surface: slightly more convex - Incisal edge: pretty flat, greater curvature at center - Crown to Root ratio: 1:1.5 - Smooth labial surface - Root tip favors distal side - Mesial View - Incisal edge centered/parallel with long axis of tooth - Mesial cervical curvature greater than distal cervical curvature - Lingual View - Cingulum wider mesio-distally and inciso-cervically than max lat incisor - Incisal View - Relatively flat facial tooth surface - Tipped more lingually than facially - Tapers more towards lingual Max Lat Incisor - Facial view - - - - - Mesial-incisal edge: less sharp - Distal-incisal edge: rounded - Distal surface: more convex than mesial - Root tip curvature pointed distally - Root is 1.5x longer than crown - Multiple crown variations - Incisal edge of lat incisor shorter than cent by 1-2mm from central incisor (shorter) Lingual view - Mesial and Distal marginal ridges: more prominent - Lingual fossa: smaller but deeper than max cen incisor - In general, landmarks not as prominent - May have developmental groove near cingulum Mesial view - Incisal edge centered/parallel with long axis of tooth - Mesial cervical curvature slightly greater than distal cervical curvature Distal View - Distal marginal ridge not as concave as mesial - Facial/lingual surfaces curve down lingually Incisal View - Labially lingually thicker than max cen - Facial surface is more curved/arched than max cen Mand Cen Incisor - - - Facial Lingual Mesial - Mesial-incisal edge: sharp 90 deg Distal-incisal edge: sharp 90 deg Mesial and Distal surface: straight Mesial/distal symmetry = hard to identify Flat incisal edge perpendicular to long axis Medio-distal width is ½ width of max cen incisor Sometimes, root curves distally Landmarks sort of indistinct/blend together Cingulum centered mesial-distally Incisal edge slightly lingual from center of tooth S-shaped lingual curve Shortest root in arch Root is thinner mesial-distally than facial-lingually CEJ high on crown (covers ⅓ of it) vs CEJ on distal side - Distal - Developmental root depression greater on distal side vs mesial - Flat incisal to facial plane ⅓ to ½ of coronal portion of crown (?) - Incisal - Straight incisal edge mesial-distally and perpendicular facial-lingually - Incisal edge a bit more on on the lingual side - Quite symmetrical and bulky Mand Lat Incisor - - - - - Facial - Mesial ½ and Distal ½ asymmetric - Usually, distal edge is more curved, bulkier, shorter - Mesial edge is straighter, sharper, longer - Slightly larger than mand cen incisor Lingual - Cingulum slightly off-centered distally - Mesial surface: straight - Distal surface: slightly convex - Marginal ridges more prominent than mand cen incisor - Mesial marginal ridge slightly longer than distal marginal ridge Mesial - Incisal edge slightly lingual from center of tooth Distal - Developmental root depression greater on distal side vs mesial - Flat incisal ⅓ to ½ facial plane? Incisal - Facial-lingually longer and larger than mesial-distal - Asymmetric - Distal-incisal edge curves towards lingual to follow arch curve (only crown, the root stays straight)