(DD13-14) Dental Anatomy .pdf - Summary of Tooth Formation SAADDES Dental papilla Ectomesenchyme from neural crest Dental follicle 95 1 Saad Alqahtani

(DD13-14) Dental Anatomy .pdf - Summary of Tooth Formation...

This preview shows page 1 out of 443 pages.

Unformatted text preview: Summary of Tooth Formation SAADDES Dental papilla Ectomesenchyme from neural crest Dental follicle 95- 1 Saad Alqahtani, Twitter @saaddes SAADDES Stratum intermedium Inner enamel epithelium Central cells of the dental papilla enamel epithelium The bell stage of tooth development, which ex hibits d ifferentiation of the too th germ to its fim hest extent. Note the enamel organ and the dental papilla have differentiated into various layers in preparation for the apposition of enamel and dentin. 308A·I Reproduced \1,-ilh p~nnission from Ba1h-Balogh M, Fehrenbac-h MJ; 11/u.ftraled Demal EmhtJ'illogy. Histology. am/ A11aiMI)~ ed 2. St. Louis. 2006. Saunders. Saad Alqahtani, Twitter @saaddes Stages in Tooth Development Stageffi me Span* Hlltlation stage/sixth to seveth weeks Micr oscopic Appearance Main Processes Involved Induction Description Ectodenn lining stomedeum gives rise to oral epithelium and rhen to dental lamina. adjacent w deeper ec1omese.nchyme, which is influenced by the neural crest cells. Both tissues are separated by a SAADDES baseme-n t membrane. Bud srage/e.ighth week P-roliferation Growth of dental lamina into bud that peneu·ates growing ectomesenchyme. Cap stage/ninth to renth weeks Proliferation, difTe.rentiation, morphogenesis Enamel organ fo nns into cap, surrounding mass of de.ntal papilla from the e.crome.o;endtyme and surrounded by mass of dental sac also from the eccomesenchyme. Fonnation of the rooth gel'llt. * Note that these are approximate prenatal time spans for the development of the primary dentition 3088~ R<'produccd \ltith penni$.«iion (rom Ebtb-Balogh M. Fchrcnbacoh MJ; Jlill.~trale(/ Demal Emb'J'ology. Histology. om/ A11a/OP1)~ ed 2. StLouis. 2006. Saunders. Saad Alqahtani, Twitter @saaddes Sta ges in Tooth development Sta geffi me Span* Bell stage/eleventh [0 twelfth weeks Maturation stage/ varies per tooth Main Processes Involved P-roliferation, ditTerentia. tion, morphogenesis Description Differentiation of enamel organ into bell with four cell types and dental papilla into two cell rypes. SAADDES Apposition stage/ varies per tooth Microscopic Appearance Induction. prolifermion De.ntal tissue..; secreted as ma£rix in successive layers. Maturation Dental tissues fully mineralize [ 0 their mature levels. * Note that these are approximate prenatal time spans for the development of the primary dentiti on 308 C.l Reproduced with p..-nnission (rom Bath-Balogh M. Fehrenbach MJ; /1/ii.~trauNI Demo/ EmhtJ'illogy. Histology. om/ AIIOIOPIJ~ ed 2. St Ll"'Uis. 2006. Saunders. Saad Alqahtani, Twitter @saaddes anterior teeth information A stray crown is found in your office. It is an anterior tooth and has a cingulum that is offset from center. What tooth is it most likely to be? • maxillary canine • maxillary lateral incisor SAADDES • mandibular lateral incisor • mandibular central incisor copyngh t 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • mandibular lateral incisor A cingulum (also cal led the linguocervical ridge) is the lingual lobe of an anterior tooth. It makes up the bulk of the cervica l third of the lingual surface. Anterior teeth that have a cingu lum located in the center of the cervica l third of the lingual surface: • Maxillary lateral incisor • Maxillary canine • Mandibular centra l incisor Anterior teeth that have a cingu lum which is located off center to the distal in the cervical third of the lingual surface: • Maxillary centra l incisor • Mandibular lateral incisor • Mandibular can ine SAADDES Note: The total number of cingula in each dentition is twelve (six maxillary anterior teeth and six mandibular anteri or teeth). Mandibular Right Lateral Incisor Mandibular Right Central Incisor D M Incisal Incisal Saad Alqahtani, Twitter @saaddes anterior teeth information Which characteri stic below is common to all mandibular anterior teeth? • distinct cingula w ith grooves and pits • incisal edges that are facial to the root axis line • facial surfaces that are marked by pronounced labial ridges SAADDES • continuous convexity incisoapically on the facial surface copynght 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • continuous convexity incisoapically on the facial surface Three characteristics common to all mandibular anterior teeth: 1. Indistinct cingula with smooth lingual anatomy without grooves and pits 2. Incisal edges lingual to the root axis line 3. Continuous convexity incisoapically on the facial surface Specific information pertaining to mandibular central incisors: • Occlusion: they only occlude with one other tooth - the maxillary central incisor (in centric, protrusive, and lateral protrusive as well) Note: The alveolar process is th innest facial to both central incisors (for this reason, local infiltration may be effective for anesthetizing these teeth). *** Remember: The canines (both maxillary and mandibular) are the only teeth with labial ridges. SAADDES Note: The CEJ curvat ures are greater on the mesial than the distal (see pictures below). / { ... \\ \ /\ I ' \ ,./ l ))\ l \ / / . I I... \. .... ' '.: J 1 ' v v ' Mesial Distal Mandibular right central incisor Mesial Distal Mandibular right lateral incisor Mesial Distal Mandibular right canine Saad Alqahtani, Twitter @saaddes anterior teeth information A clinical examination of your patient reveals two lower incisors centered on the midline. The patient gives a history of a car accident when he was young where he lost two of his lower front teeth. He says that his dentist used braces to fill in the gaps. Which of the following criteria would be most reliable to decide ifthe remaining teeth were lateral or central incisors? SAADDES • difference in root length • difference in ratio of crown length to root length • degree of slope of the incisal edge when viewed facia lly • difference in rotation of the crown on the root copynght 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • difference in rotation of the crown on the root *** The mandibular lateral incisor crown t ips sli ghtly to the distal relative to t he root (facial view). Other ways to distinguish the mandibular lateral from the mandibular central: • The lateral is larger overall (especially mesiodistally) • The lateral is not as b il aterally symm etrical as the centra l incisor • The cingulum on the lateral is slightly distal to the center • On the lateral inciso r, the mesial marginal ridge is longer than the distal marginal ridge. On centrals, they are the same lengt h • Lateral incisors have t he distal p roximal contact s more apical t han the mes ial contacts. Centrals are at the same level • Lateral incisors have the distoincisal angles more rounded than the mesioincisal angles. On centrals, the angles are nearly the same SAADDES Note: Both the mandibular central and lateral have a lingual cervical line t hat is positioned more apically than the facial cervical line. Mandibular Right Lateral Incisor M Labial 4 Incisal Mandibular Right Central Incisor M~ D Labial D lnc.isal Saad Alqahtani, Twitter @saaddes anterior teeth information The mesial and distal aspects oft he anterior teeth- central incisors, lateral incisors, and canines, maxillary and mandibular - may be included within triangles. The base of the triangle is represented by the cervical portion of the crown and the apex by the incisal ridge. SAADDES • both statements are true • both statements are fa lse • the first statement is true, the second is fa lse • the first statement is fa lse, the second is true copynght 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • both statements are true Outlines of crown forms within geometric outlinestriangle, trapezoids, and rhomboids. The upper figure in each square represents a maxillary tooth, the lower figure a mandibular tooth. Note t hat the trapezoidal outline does not include the cusp form of posteriors actually. It does Include t he crowns from cervix to contact point or cervix to marginal ridge, however. This schematic drawing is intended to emphasize certain fundamentals. A, Anterior teeth, mesial or distal {triangle). 8, Anterior teeth, labial or lingual (trapezoid). C, Premolars, buccal or lingual {trapezoid). 0, Molars, buccal or lingual {trapezoid). E, Premolars, mesial or distal (rflombold). F, Molars, mesial and distal (rhomboid). SAADDES Summary of Schematic Outlines of the Tooth Crowns: • Triangles Six anterior teeth, maxillary and mandibular - mesial and distal aspect • Trapezoids Trapezoid with longest uneven side toward occlusal or incisal surface • All anterior teeth, maxillary and mandibular - labial and lingual aspect • All posterior teeth- buccal and lingual aspect Trapezoid with shortest uneven side toward occlusal surface • All maxillary posterior teeth- mesial and distal aspect • Rhomboids • All mandibular posterior teeth- mesial and dista l aspect Saad Alqahtani, Twitter @saaddes anterior teeth information Which of the following statements best describes the pulp canal of the mandibular lateral incisor? • an elliptical shape, consistently w ider in the mesiodistal direction • an elliptical shape, consistently w ider in the facio lingual direction SAADDES • an elliptica l shape, wider in the mesiodistal direction in the pulp chamber, but wider in the faciolingual d irection in the mid-root area • an elliptical shape, w ider in the facio lingual d irection in the pulp chamber, but w ider in the mesiodistal direction in the m id-root area copynght 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • an elliptical shape, wider in the mesiodistal direction in the pulp chamber, but wider in the faciolingual direction in the mid-root area Near the roof of the pulp chamber, the elli ptical form of the pulp cavity is widest in the mesiodi stal direction; however, near mid-root the elliptical form is widest in the facio lingual d irection. A small percentage have two canals. ·-""-~):;) 1. Compared to the mandibular cent ral incisor, the mandibular lateral incisor's root is larger in all dimensions. 2.The crown of the mandibular lateral incisor tips slightly to the distal relative to the root; thu s, the cingulum is slightly off-center to the distal, like that of the maxillary central incisor and mandibular canine, but unlike that of the mand ibular central incisor. 3. The incisa l edge of the mandibular lateral is slightly curved or rotated on the distal. For this reason it is possible to see a small portion of this distal-incisal edge w hen viewing this tooth from the mesial aspect. SAADDES Mandibular Right Lateral Incisor Mesiodistal cross-section Mandibular Right Central Incisor Cervical Cervical cross-section cross-section labiolingual cross-section Mesiodis1ol c ron·section labiolingual cross-section Saad Alqahtani, Twitter @saaddes anterior teeth information Which of the following line angles is least "square"? • mesioincisal of the mandibular lateral incisor • distoincisal of the mandibular lateral incisor • mesioincisal of the mandibular central incisor SAADDES • distoincisal of the mandibular central incisor copynght 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • distoincisal of the mandibular central incisor The distoincisal angle of most anterior teeth ismore rounded compared to the mesioincisal angle. Another way to say this is that the mesioincisal angles are more square (or acute) than the distoincisal angles, which are more obtuse. Hint: Distal is rounded like the letter"D"; mesial is straighter like the letter "M~ !. Important: The mandibular central is the only anterior tooth in which the distoincisal angle is as sharp and disti nct as the mesioincisal angle. All other incisors show a more or less rounded distoincisal angle. 2. Anterior teeth are highly important aesthetically and play an important role in the formation of many speech sounds ("V~ "F: and "TH"). When viewed from the sagittal plane, the axial inclination of the anterior teeth inclines facially. \l:nlllaJ' and \landJb ulaJ lm1~on SAADDES 8,9 1.10 24.;25 2 3.26 Slight rounding Shal]l right angle Some rounding Slight rounding Oistincc roond Sha'll right angle M ot~" rounded Straight Slight rounding Straight Straiglu Ncsrlyround Oistincc round Straight Su'3iglu Straight Straight Straight Straight Ol twist lncisslthird Junction Jun~"1ioo Middle third Incisal th ird lncis:al tb ird Incisal third Ml angle Shsrp right angle Dl angle Mcsialprotilc Dist~ll profile Incisal outline Proximal contacts Mesial Distal l nci~al third Maxillary Right Central Incisor Maxillary Right Lateral Inci sor Mandibular Right Lateral lncisor Labial labial labial Mandibular Right Centrallncisor Labial Saad Alqahtani, Twitter @saaddes anterior teeth information Which tooth has a pulp chamber that is least like the others? • maxillary central incisor • mandibular central incisor • maxillary lateral incisor SAADDES • mandibular lateral incisor copynght 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • maxillary central incisor The pulp chamber of the maxillary central incisor is wider in the mesiodistal dimension than in t he labiolingual d imension. The pulp cavity conforms to the general shape of the outer surface of the tooth. The pulp cavity is widest at the cervical level, and the pulp chamber is centered within the dentin of the root. In young individuals, the pulp chamber is roug hly triangular in outline with the base of the triangle at t he labial aspect of the root. As the amount of secondary dentin increases, the pulp chamber becomes more round or crescent-shaped . Also, the size of t he pulp chamber decreases in size. The cervical cross sections of the pulp of permanent anterior teeth SAADDES Max. Central Incisor Max. Lateral Incisor Max. Canine Mand. Central Incisor Mand. Lateral Inci sor Mand. Canine Saad Alqahtani, Twitter @saaddes anterior teeth information When looking at the facial or lingual aspect of all anterior teeth, they have a: • trapezoidal outline • triangular outline • rhomboidal outline SAADDES • square outline copynght 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • trapezoidal outline The trapezoidal outline has its longest uneven side toward the occlusal or incisal surface. {j {j 0 Facial view of the Maxillary Right Central Incisor Facial view of the Mandibular Right Lateral Incisor Lingual view of the Maxillary Right Canine Lingual view of the Maxillary Right Lateral Incisor SAADDES Remember (from card #4): 1. The mesial and distal aspects of all maxillary posterior teeth have a trapezoidal outline. The shortest uneven side is toward the occlusal surface. 2. The buccal and lingual aspects of all posterior teeth have a trapezoidal outline. The longest uneven side is toward the occlusal surface. 3. The mesial and distal aspects of all mandibular posterior teeth have a rhomboidal outline. 0 Mesial view of the Maxillary Right First Molar wa Lingual view of the Maxillary Right First Molar Mesial view of the Mandibular Right First Molar Saad Alqahtani, Twitter @saaddes canine teeth information In maximum intercuspation, which anterior tooth is unique in that it contacts with both anterior and posterior segments of the opposite arch? • maxillary first premolar • maxillary canine SAADDES • mandibular first premolar • mandibular canine copynght 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • maxillary canine There is no contact on the cusp tip. It fa lls in direct alignment with the facial embrasure between the mandibular canine and first premolar. This anterior tooth is unique in that it has antagonists, in the intercuspal position, in both anterior (canine) and posterior (first premolar) segments of t he opposite arch. \l:nillar~ Canines Characteristics FaciaULabial a spect Proxima l contacts Mes ial Distal Junction of the incisal and middle third Middle third Mesial aspect Wider faciolingually Lin gual a sp ect Margina l ridges Cingu lum Lingual pi ts, grooves Deeper lingua l fossae Pronounced; 2 fossae Large, centered MD Common Incisal aspect Marked symmetry of mesial/distal ha lves SAADDES Incisal/Proximal aspects Cusp tip may be at or labial to root axis line CEJ curvature 2.5 mm (mesial) Contour Height Facial/lingual O.Smm Both cervical third Saad Alqahtani, Twitter @saaddes canine teeth information A hockey player comes into your office with his six upper anterior teeth in his hand. How can you distinguish the right canine from the left canine? • the root always curves to the distal in the apical one-third • the distal surface is fuller and more convex than the mesial surface SAADDES •labially, the cusp tip is placed distal to a line which bisects the crown and root •linguall y, the cervical line slopes mesially 10 copynght 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • the distal surface is fuller and more convex than the mesial surface Also remember that: • The curvature of the cervical line is greater on the mesial side than on t he d istal side • The mesial surface is straighter than the distal surface • The d istal cusp ridge is longer than the mesial cusp ridge • The mesial contact point is at the junction of t he incisal and midd le third • It usually thicker labiolingually than it is mesiodistally • The tip of the cusp is displaced labially and mesial to the central long axis of the tooth • The d istal contact is in a more cervical position (middle of the middle third) • Althoug h the apical l /3 of the root typically curves distal, t his is not always true. SAADDES Maxillary Right Canine C\ISP~ Facial lingual Saad Alqahtani, Twitter @saaddes canine teeth information Which of the following terms is specific to canines? •labial ri dge • lingua I fossa • mamelons • cingulum SAADDES 11 copyngh t 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • labial ridge The labial (facial) surface of canines is marked by a pronounced labial ridge (see facial view below). Shallow developmental depressions lie mesial and distal to t he labial ridge. On the mandibular canines, the labial ridge and the developmental depressions are not as pronounced. Important: The canines (both maxillary and mandibular) are the only cusped teeth which feature a functional lingual surface rather than a functional occlusal surface. ~ 1. Looki ng at the maxillary canine from a facial view, the d istal portion of the facial surface is convex in t he middle t hird and slig htly concave in the cervical third. The mesial portion is convex in the middle third and nearly flat in the cervical third. 2. From the incisal view, the cervical line is often not visible. This is due to the convexity of t he crown. SAADDES Maxillary Right Canine Mandibular Right Canine l a bial ridge labial ridge Cusp tip Facial Facial Saad Alqahtani, Twitter @saaddes canine teeth information A mother brings her three kids to your office for their annual check-ups. Which of the following statements is most likely to be true? • the m iddle ch ild is 11 and has no adult canine teeth • the youngest ch ild is 10 and has adult mandibular canines only SAADDES • the oldest child is 12 and has maxillary canines only • the youngest ch ild is 10 and has adult maxillary canines only • the oldest child is 12 and has mandibular canines only 12 copynght 0 20 13·2014 Dental Decks DENTAL ANATOMY & OCCLUSION Saad Alqahtani, Twitter @saaddes • the youngest child is 10 and has adult mandibular canines only ***Going by the known eruption ages, t he most plausible scenario is that the 10-year- old has her mandibular canines but not her maxillary canines. Remember: • Maxillary canines erupt between the ages of 11 -12 (after the premolars} • Mandibular canines erupt between the ages of 9-10 (before the ...
View Full Document

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture