Week 7: Anatomy of Permanent Maxillary Central Incisors PDF

**[Week 7]** ------------------------ **Dr Sfera L1- Anatomy of permanent maxillary central incisors** **Appearance** - Anterior presentation, either side of the midline-ideally present as mirror image - FDI 11 and 21 - Mesiodistally- the widest permanent incisor - Squared/rectangu...

**[Week 7]** ------------------------ **Dr Sfera L1- Anatomy of permanent maxillary central incisors** **Appearance** - Anterior presentation, either side of the midline-ideally present as mirror image - FDI 11 and 21 - Mesiodistally- the widest permanent incisor - Squared/rectangular appearance - Symmetrical crown **Development** - First sign of calcification- 3-4 months of life - Crown complete- 4-5 years - Erupt 7-8 years **Labial aspect** - Labial surface convex from mesial to distal and cervical to incisal - 4 line margins/line angle visible (M, D, I, C) - 2 angles visible (MI, DI) - Mesial margin-longer and straighter than the distal - Mesio incisal angle is relatively sharp/sharper than the disto-incisal - Incisal margin straight after the mamelons wear off - The root-cone shaped with a blunt apex **Palatal (lingual) aspect** - Predominantly concave surface - Mesial and distal present as distinct ridges - Often has a shovel shaped appearance - Cingulum located near cervical margin-it's a convex feature - Lingual fossa- the deepest part-towards incisal - A ridge of enamel may point towards the incisal margin dividing this surface into two shallow fossa **Mesial and distal aspects** - Triangular/wedge shaped- with the base at the cervix and apex at the incisal tip - The cervical curvature of the CEJ is greater on the mesial aspect. Contact area is the incisal 1/3 - Distal aspect is similar however the CEJ is less exaggerated **Dr Sfera- L2 Maxillary Lateral incisors** **Appearance** - FDI 12 and 22 - Complement the central incisors in appearance and function - Second in the incisor sequence - Smaller than maxillary central (except root length) - Same features but often condensed/exaggerated **Development** - First signs of calcification- 10-12 months - Crown completion- 4-5 years - Eruption- 8-9 years - Mamelons are present in young teeth but are less pronounced than in central **Variations in appearance** - Display the most variation in form (apart from 3^rd^ molars) - If the variation is too great it is considered a developmental anomaly - Common- Mx lateral incisors of non-descript conical pointed from- peg laterals **Hypodontia** - Most common tooth to be congenitally missing, either singly or bilaterally in 1-2% of the population **Labial aspect** - Mesio incisal angle sharper than the distal - Mesioincisal and distoincisal angles more rounded than centrals - Labial surface is more convex that Mx centrals - Narrower mesio distally and shorter cervicoincisally that Mx centrals - Incisal line slopes more on the mesial aspect that centrals **Palatal aspect** - Mesial and distal margins are more pronounced than in central - Cingulum is usually prominent thus the palatal concavity appears deeper - A large, pointed tubercle may also present as part of the cingulum - Deep pit may be present in the cingulum-foramen caecum. This may extend towards the root of the tooth - Be sure to examine this area carefully using triplex air syringe- caries predilection spot **Mesial and distal aspects** - Wedge shaped - Mesial aspect displays greater curvature of the CEJ than the distal - Distal surface quite rounded-similar to mesial aspect on canine - The root appears longer-shape of a tapered cone - Apical end pointed or sometimes blunt - Contact area- incisal 1/3 **Root structure** - Same length as the centrals root- may be longer - Apical 1/3 often distally inclined and terminates sharply - Narrow/flattened mesiodistally **Dr Sfera L3 -- Anatomy of mandibular central incisors** **Appearance** - The smallest tooth in permanent dentition - FDI- 31 and 41 - Smooth labial surface with no clear developmental lines - Mamelons present when newly erupted-wear off rapidly if in normal occlusion **Development** - First sign of calcification- 3-4 months - Crown complete- 4-5 years old - Eruption- 6-7 years - Mosty likely the first succedaneous tooth in the mouth **Labial aspect** - Regular and convex - Crown 2x long as wide - Symmetrical in shape - Roughly triangular- narrow at the cervix - Rounded CEJ - Mesio-incisal angle is relatively sharp/sharper than the disto-incisal - Incisal ridge at a right angle to the long axis of the tooth **Lingual aspect** - Lingal surface, smooth and slightly concave from incisal to cervical - Less concave from mesial to distal - Lingual cingulum, mesial and distal marginal ridges are less defined than in maxillary incisors - Rarely are lingual pits/fissures present - Root tip may have a slight distal curve **Mesial and Distal aspects** - Triangular in outline - Base is towards the root - Cervical line (CEJ) outline may be the same on both sides - If a difference in CEJ is present, then mesial aspect presents with greater curvature - Incisal edge has a labial inclination as a result of occlusal wear - Contact areas are in the incisal 1/3 **Dr Sfera L4- Anatomy of permanent mandibular lateral incisors** **Lateral incisor** - Closely resembles the mandibular central - FDI 32 and 42 - Slightly larger and is more asymmetric in shape than the mandibular central - Disto-developmental lobe is wider than that of the mandibular central - Slightly wider mesio-distally, longer inciso-cervically **Development** - First sign of calcification- 3-4 months - Crown complete- 4-5 years - Erupt- 7-8 years of age **Labial aspect** - Usually greater mesio-distal dimension by 1mm - Mesial side slightly higher than the distal - Incisal edge slopes down towards distal - Mamelons are present in newly erupted teeth **Lingual aspect** - Ridges are slightly more developed - Lingual fossa appears shallow- a lingual pit may also be present - Root can be considerably longer than in Md central - Proximal grooves often give the appearance of a double root - Apex may have a labial/distal inclination **Root structure** - Root-delicate - Flattened mesio-distally - Longitudinal grooves on mesial and distal - Distal groove is often deeper than mesial - Apex may have a distal deflection **Dr Sfera L5- Anatomy of permanent maxillary canine** **Cuspid** - 3^rd^ tooth from midline - Last of the anterior teeth - Single root and cusp - Longest root in the dentition - Used for seizing/tearing food - Incisal edge/ridge replaced by a cusp tip and line margins (cusp ridges) **Appearance** - FDI 13 and 23. Morphologically and functionally share characteristics with both incisors and premolars **Development** - First evidence of calcification- 4-5 months - Crown complete- 6-7 years - Erupt- 11-12 years **Canines** - Cusp tip replaces the incisal edge/ridge present on the other anteriors - Cusp tip lies in line with the long axis of the tooth - Narrower mesiodistally than Mx central incisor **Labial aspect** - Convex mesiodistally and cervicoincisally - Mesio-incisal line angle is shorter than the distal - Made up of four lobes - 3 facial lobes and 1 lingual - Mid-facial lobe extension is most developed and forms a cusp tip - Cusp tip occupies approximately 1/3 of crown height - 2 shallow developmental grooves on the labial aspect sometimes present **Palatal aspect** - Palatal lobe makes the cingulum which is more developed than incisors- canines are wider labiopalatally - If a well-developed lingual ridge is present, then mesial and distal lingual fossae are visible - Palatal aspect may also be smooth - Palatal aspect is smaller than the labial **Mesial and Distal aspect** - Wedge shaped - Labial surface is more convex than the incisors from this view - Contact surface towards the incisal 1/3 mesially and in the mid 1/3 distally - Root appears conical from this view **Root** - Long and robust root - Root shape- triangular on a cross-section/ This helps to resist anterior, posterior and lateral displacement forces - Root is wider labially than palatally - That labio-palatally - Root apex is generally blunt - May have a palatal or distal inclination **Dr Sfera L6- Anatomy of mandibular canines** **Appearance** - FDI- 43 and 33 - Closely resembles the Mx canine - Crown is narrower than in Mx canine but can be of the same height - The cusp occupies only 1/5 of the crown height - Cusp is less pointed **Development** - First sign of calcification- 4-5 months - Crown completes- 6-7 years - Generally erupt around- 9-10 years **Root** - The root as long as in Mx canine (can even be longer) - Root is oval in cross section and shows distinct developmental depressions on mesial and distal surfaces - Can be quite pointed at the apex - Lower canine may present with a bifurcation at the apical 1/3 of the root **Labial aspect** - Mesio incisal line angle is shorter than the distal - Pronounced labial ridge - Crown may be slightly longer and more symmetrical than the maxillary - Cusp tip not as developed as in the maxillary canine's crown **Lingual aspect** - Lingual features are less pronounced than in the Mx canine - Less developed cingulum and thinner marginal ridges - No lingual pits present - Lingual fossae less developed **Mesial** - Wedge shaped and a pointed cusp - Cusp tip is on the long axis of the tooth cervical line curves towards the incisal - Contact area towards the mesio incisal angle **Distal** - The whole surface more curved than the mesial - Cervical line shows less curvature toward the cusp tip - Contact area towards incisal 1/3 **[Dr Touraj- L1- GIC]** **Spectrum of tooth coloured filling materials**  **Presentation of GIC** A black and white text on a black background Description automatically generated **GIC setting**  **Polyacrylic acid** A collage of images of different chemical formulas Description automatically generated **Tartaric acid** - Improves working time and reduces setting time i. contributes to better homogeneity in the cement mix, leading to improved mechanical properties. It also interacts with the polyacid and glass particles in the cement, promoting release of ions like Ca and Al **Maleic acid and itaconic acid** - enhances the adhesive properties of the GIC by increasing the number of carboxylic acid groups available for bonding with the tooth surface - Helps create a denser cross-linked network within the cement matrix, leading to improved compressive, tensile and flexural strength - Similar to tartaric, maleic acid can influence the setting characteristics of the cement. Maleic acid aids in the release of fluoride and calcium **Bonding to tooth structure** - GIC can bond to dentine and enamel - Bonding to calcium-appetite by ionic bond - Bonding to collagen by H bond - Surface cleaning and condition especially with 10-20% polyacrylic acid to obtain a good bonding to dentine especially for long term is required. However, tensile strength of bonding is low (7MPa) compared to resin bonding agents (20MPa) - Conditioner is recommended for placing GIC in long term cavity - The 10% polyacrylic acid solution is applied for 20 seconds to modify smear layer **Moisture sensitivity** - Aluminium ions may leach out due to contact with saliva result in poor strength - Contamination with saliva, blood will result in poor aesthetic, strength and bonding - Drying retards the setting reaction - Careful isolation and application of a protective cover such as varnish, GIC coat or light-activated bonding agents for 24 hours is recommended - Higher P/L ratio reduces the setting time and increases the strength **Problems with GIC** - Erratic dispensing, high solubility, poor aesthetic, low strength and toughness, moisture sensitive, poor wear resistance **Clinical indications of GIC**  **GIC advantages and disadvantages** A black background with white text Description automatically generated **Resin modified GIC** - Powder 1. Radiopaque fluoroaluminosilicate glass 2. Pigments - Liquid 1. Polyacrylic acid 2. HEMA 3. Photoinitiators 4. Water **Combined cross-linking and hardening in RMGI (advantages)** - Fluoride release, adhesive to enamel and dentine, bulk placement only in case of Ketac-Cem plus, biocompatible, chemical cured or VLC, immediate finishing, low solubility, good aesthetic in the case of Fuji II LC **Clinical indications of RMGICs**  **Applications of GIC and RMGIC** - Crown cementation, post-core cementation, pit and fissure sealant