Oral Anatomy Prelim Handout PDF

ORAL ANATOMY – PRELIMINARY HANDOUTS DENT 221 – ORAL ANATOMY LECTURE PRELIM TOPICS INTRODUCTION TO ORAL ANATOMY FORMATION OF HUMAN DENTITION PRIMARY/ TRANSITION/ SU...

ORAL ANATOMY – PRELIMINARY HANDOUTS DENT 221 – ORAL ANATOMY LECTURE PRELIM TOPICS INTRODUCTION TO ORAL ANATOMY FORMATION OF HUMAN DENTITION PRIMARY/ TRANSITION/ SUCCEDENEOUS DECIDUOUS MIXED / PERMANENT First set of teeth Period where Replaces to be seen in there is a exfoliated the mouth mixture of deciduous teeth deciduous and in a sequence of succedeneous eruption teeth present Begin to form Begin to erupt Last from 6-12 prenatally at at 6years of age years of age and about 14weeks ends when all Fig 1 in utero deciduous teeth have been shed Begin to form in Begins during Completed Crown VS Root the oral cavity the emergence (including the Anatomical Crown Refers to the crown (entire) which is at 6months of the 1st roots) at about covered by enamel (mean age) permanent 14-15years of molars age; except for Clinical Crown Refers to the crown which is visible 3rd molars clinically Completed Completed Anatomic Root Refers to the root (entire) which is post-natally at permanent covered by cementum about 3 years dentition consist Clinical Root Part of the tooth which is under the of age, consist of 32 teeth gingiva and is not exposed to the of 20 teeth oral cavity TERMINOLOGIES IN TOOTH MORPHOLOGY Structure of the tooth o Enamel – outer covering of the crown o Dentin – supports the enamel; main bulk of the tooth o Cementum – covers the root of the tooth o Pulp – furnishes the blood and nerve supply to the tooth; inner portion of the tooth, the only Fig 2 soft tissue of the tooth, Supporting structure of the tooth o Alveolar bone – bony process of the jaw serving as support for the tooththe bone that supports EXTERNAL MORPHOLOGY OF THE ANATOMIC ROOT the tooth Apex – terminal end of the root of the tooth o Periodontal Ligament – anchors the root of the Apical formina/ apical foramen – opening of the tooth to the alveolar bone pulp canal at the apical end of the root o Gingiva – soft tissue that surrounds and covers Cervix – (Cervical line) or CEJ (Cementoenamel the base of the tooth junction) where the crown and root join ©rjcadmd 1 ORAL ANATOMY – PRELIMINARY HANDOUTS Root trunk – only seen in multirooted teeth, the Palmer Notation System (Zsigmondy Notation undivided cervical portion of the root system) Furcation (bifurcation/trifurcation) – area in o In this system the arches are divided into which the roots of multirooted tooth divides. quadrants with the entire dentition being notated as follows: o Primary : it starts on the central incisor (A) to 2nd molar (E) o Permanent: starts on the central incisor (1) to 3rd molar (8) FDI Notation System (Federation Dentaire Fig 3 Internationale) o 2-digit system for both primary and permanent dentitions FORMULAE FOR MAMMALIAN TEETH § 1st digit = quadrant, 2nd digit = tooth Primary Dentition Permanent Dentition TOOTH NUMBERING SYSTEM SURFACES, RIDGES AND OTHER LANDMARKS Universal Notation System Labial Surface – towards the lips, can only be o Uses uppercase letters for each primary seen on anterior teeth (Incisors to Canines) teeth Buccal Surface – towards the cheeks, can only o For maxillary arch beginning with the right be seen on posterior teeth (premolars to second molar, letters A through J, and molars) o For the mandibular teeth, letters K through Facial Surface – collective name for labial and T, beginning with the left mandibular second buccal surface molar Lingual Surface – facing towards the tongue Palatal Surface – facing towards the palate Occlusal Surface – surface of posterior teeth that come in contact with the teeth on the opposing arch during the act of closure o Permanent teeth: The maxillary teeth are Incisal Surface - surface of posterior teeth that numbered from 1 through 16, beginning come in contact with the teeth on the opposing with the right third molar arch during the act of closure ©rjcadmd 2 ORAL ANATOMY – PRELIMINARY HANDOUTS Proximal Surface – sides of the tooth; where teeth, and mesial and distal margins of the contact areas and height of contour (crest of lingual surfaces of the anterior teeth curvature) is found o Mesial – towards the midline o Distal – away from midline o Triangular ridge – descend from the tips of the cusp of molars and premolars toward the central part of the occlusal surface o Transverse Ridge – union of two triangular ridges Fig 4 ELEVATIONS: Cusp - An elevation or mound on the crown portion of a tooth making up a divisional part of the occlusal surface Fig 5 Tubercle - a smaller elevation o Oblique Ridge – ridge crossing obliquely the on some portion of the crown produced by an occlusal surface of maxillary molars and extra formation of enamel formed by the union of the triangular ridge o “dens evaginatus” – extra cusp fron affected of the enamel organ distobuccal cusp and the distal cusp ridge of the mesiolingual cusp Fig 6 Lobe – one of the primary sections of formation Cingulum – the lingual/palatal love of an anterior in the development of the crown tooth; makes up the bulk of the cervical 3rd of the lingual surface Fig 7 Ridge – linear elevations on the surface of the tooth o Marginal Ridge – rounded borders of the enamel that form the medial and distal margins of the occlusal surface of posterior ©rjcadmd 3 ORAL ANATOMY – PRELIMINARY HANDOUTS o Represented by cusps and mamelons Sulcus – long depression or valley in the surface of § Mamelons – any of the three a tooth between ridges and cusps. protruberances found on the incisal ridges of newly erupted incisor teeth DEPRESSIONS: Fossa – irregularly depressions or concavity o Lingual Fossa – depressions on the lingual surface of incisors Developmental grooves – shallow groove or line between primary parts of the crow or root o Supplemental Groove – less distinct, shallow linear depression on the surface of the tooth o Buccal/Lingual Groove – developmental grooves found on the buccal/lingual surfaces of the tooth. o Central Developmental Groove -located o Central fossa – depressions on the occlusal buccolingual center of the tooth sulcus and runs surface of molars mesiodistally o Triangular fossa – found on posterior teeth next to marginal ridges Pits – small pinpoint depressions located at the junction of developmental grooves ©rjcadmd 4 ORAL ANATOMY – PRELIMINARY HANDOUTS TERMINOLOGY RELATED TO IDEAL TOOTH ALIGNMENT o Important Functions: OF THE TEETH IN THE DENTAL ARCHES § Positive contact of all teeth within each Mid-Root Axis Line (Root Axis Ling/ Long Axis Line) dental arch stabilizes the position of teeth – imaginary line through the center of the tooth within the arch o Facial and Lingual – divides the tooth at the § Helps prevent food impaction cervix into mesial and distal halves § Protects the interdental papilla by diverting o Mesial and Distal – divides the tooth at the food buccally and lingually cervix into facial and lingual halves o Diastema – space that exists between two Height of Contour (Crest of Curvature) – facial or adjacent teeth in the same arch that is not the llingual height of contour result of a missing tooth o Point on a crown outline where a line drawn parallel to the mid-root axis line touches the greatest bulge o Helps determine the direction that food particles are deflected in as they are pushed o Interproximal Space – formed by proximal surfaces in contact; triangularly shaped spaces cervically over the tooth surfaces during normally filled by the gingival tissue mastication § Alveolar Process- base of the triangle § Proximal surfaces contacting the teeth - Contact Areas (Interproximal contact areas)– sides of the triangle greatest height of contour on the proximal surfaces § Area of contact – apex of triangle of tooth crowns, where one tooth touches an adjacent tooth. ©rjcadmd 5 ORAL ANATOMY – PRELIMINARY HANDOUTS Embrassure Spaces – triangular space that are DIVISIONS OF THE ORAL CAVITY narrowest and closest to coontat area where the teeth are in tight contact o They serve as “spillways” to direct food away from the gingiva Vestibule – is the space bounded by the lips and cheeks on the exterior and the gums and teeth within o It is lined by mucus membrane, which is kept moist by the secretions received from the salivary glands. This mucus membrane is continuous with the mucus lining of the lips, cheeks and alveolus of the upper and lower OROFACIAL COMPLEXES jaws BOUNDARIES OF THE ORAL CAVITY Superior Border: Hard and Soft Palate Oral Cavity Proper – is the area confined within the Anterior & Lateral Border: Lips, Upper teeth, Lower upper and lower dental arches Teeth COMPONENTS: Posterior Border: Palatoglossal folds o Hard Tissue § Skeletal unit (bone) Mandible Maxilla Skull Bones Alveolus/Alveolar Bone § Dental unit (teeth) Incisors Canines Premolars Molars o Soft Tissue § Lips – encircles the orifice of the mouth, control the opening and closing of the oral ©rjcadmd 6 ORAL ANATOMY – PRELIMINARY HANDOUTS cavity, plays an important role in speech and § Palate – deglutition Hard Palate - is the bony vault of the oral § Salivary Glands – secrete saliva; major role in cavity bounded in front and the sides by various physiologic functions the alveolar arches. It is continuous with Parotid Gland - largest the soft palate located behind it. It is Sublingual Gland covered by a firm lining formed by the Submandibular Gland adherence of the mucous membrane to the palatal periosteum and contains a few corrugations called rugae. It helps in the physical separation of the mouth from the nasal cavity and provides separate passages for the intake of air and food. § Tongue – firmly anchored to the floor of the mouth by the lingual frenum Contains many small papillae o Filiform o Fungiform Soft palate – is a movable soft tissue o Foliate suspended from the posterior border of o Circumvallate the hard palate and forms an incomplete barrier between the mouth and the pharynx. It is composed of mucous membrane overlying muscle fibres, palatine aponeurosis, blood vessels and nerves. It also contains mucous glands within its substance. DIVISIONS INTO THIRDS, LINE ANGLES, AND POINT ANGLES DIVISION OF THIRDS (CROWN AND ROOT) § Cheek - Sheet-like structures on the side of - For description purposes the face and merge with lips anteriorly; Crown Composed of muscle fibers, fat, areolar o Cervico-occlusally/cervico-incisally tissue, blood vessels and nerves and are o Faciolingually lined by skin externally o Mesiodistally § Gums/Gingiva - cover the alveolar processes Root and encircle the necks of the teeth o Cervico-Apically ©rjcadmd 7 ORAL ANATOMY – PRELIMINARY HANDOUTS When viewing from the facial, lingual, mesial and distal Lines running FACIOLINGUALLY can be used to divide surfaces, HORIZONTAL lines can divide the crown into: the tooth into: o Occlusal/Incisal 3rd o Mesial 3rd o Middle 3rd o Middle 3rd o Cervical 3rd o Distal 3rd HORIZONTAL lines can divide the root into: o Cervical 3rd o Middle 3rd o Apical 3rd When viewing from the facial and lingual surfaces, VERTICAL lines can divide the crown or root into: o Mesial 3rd LINE ANGLES o Middle 3rd - Formed by junction of TWO surfaces and o Distal 3rd derives its name from the combination of the two surfaces that join Anterior Teeth o Mesiolabial o Distolabial o Mesiolingual o Distolingua o Labioincisal o Linguoincisal Posterior teeth o Mesiobuccal o Distobuccal When viewing from the proximal (mesial/distal) o Mesiolingual surfaces, VERTICAL lines can divide the crown or the o Distolingual root into: o Mesio- o Facial 3rd occlusal o Middle 3rd o Disto-occlusal o Lingual 3rd o Bucco-occusal o Linguo-occlusal POINT ANGLES - Formed by junction of THREE surfaces and When viewing a tooth from the occlusal or incisal derives its name from the combination of the surface, line running MESIODISTALLY can be used to names of the surfaces forming it divide the crown into: Anterior teeth o Facial 3rd o Mesiolabioincisal o Middle 3rd o Distolabioincisal o Lingual 3rd o Mesiolinguoincisal o Distolinguoincisal Posterior teeth o Mesiobucco-occlusal o Distobucco-occlusal o Mesiolinguo-occlusal o Distolinguo-occlusal ©rjcadmd 8 ORAL ANATOMY – PRELIMINARY HANDOUTS DEVELOPMENT AND ERUPTION OF HUMAN o 4 – 6 months in utero = calcification of primary DENTITION teeth (crown) o Average of 10months (1month postnatal) = crown completion EXFOLIATE/ o Eruption period: 6months to 2years old ERUPTION EMERGENCE EXFOLIATION (approximately) all primary teeth are erupting used to mean The process of into the child’s mouth over this period denote the continuous shedding of the o Approximately 3years old = root completion tooth’s tooth primary teeth o Lasts for 2years old to 6 years old emergence movement and their (approximately) all primary teeth are present; through the from the replacement by no permanent teeth are yet visible in the gingiva dental bud to permanent mouth occlusal teeth contact. PRIMATE SPACES = spaces that can be seen on the distal of maxillary lateral incisors and distal of mandibular canine DENTITION TIMELINE ORDER OF EMERGENCE OF PRIMARY TEETH NO TEETH o From birth to 6months old (approximately) o There are no teeth visible within the mouth o Gum pads NATAL VS NEONATAL TOOTH o Neonatal tooth – teeth that appear on the first 30 day after birth o Natal Tooth – teeth that are present at the time of birth PRIMARY DENTITION o 6weeks in utero = initiation of the primary teeth formation; first indication of tooth formation occurs as early as the sixth week of prenatal life when the jaws have assumed their initial shape ©rjcadmd 9 ORAL ANATOMY – PRELIMINARY HANDOUTS MIXED DENTITION o Starts at approximately 6 years old; permanent teeth start to appear, beginning with the first molar (also called 6-year old molars) just distal to the primary second molars. Followed by the loss of primary mandibular incisors, which are quickly replaced by permanent mandibular central incisors o 6-9 years old = all eight permanent incisors replace primary incisors that are exfoliated (shed) o 9-12 years old = all four permanent canine and eight premolars replace primary canines and molars o 12 years old = second molars (also called 12 year old molars) emerge distal to the permanent 1st molar o Lasts for 6-12 years old o Ends with the loss of the last primary tooth CONSEQUENCES DURING MIXED DENTITION o Premature loss of primary teeth = likely to cause a loss of arch length with a consequent tendency for crowding of the premanent dentition o Long retention of primary teeth ©rjcadmd 10 ORAL ANATOMY – PRELIMINARY HANDOUTS PERMANENT DENTITION o At approximately 12 years old, all permanent teeth are present except 3rd molars, and all primary teeth have been exfoliated and replaced. o 17-21 years old – 3rd molar emergence ORDER OF EMERGENCE OF PERMANENT TEETH ©rjcadmd 11 ORAL ANATOMY – PRELIMINARY HANDOUTS PRIMARY (DECIDUOUS DENTITION) Aka “temporary”, “milk”, “baby” teeth Importance of Primary Teeth Development of oral motor behavior and the acquisition of masticator skills Efficient mastication of food Provide support for the cheeks and maintaining of a normal facial appearance and smile Formulation of clear speech Maintenance of proper diet Maintain of space and arch continuity required to provide room for the emergence of the permanent teeth Missing and badly decayed deciduous teeth are important reasons why children reject foods that are essential for their growth and development. o Periapical infection in a deciduous tooth can cause dark spots (Turner’s spots) on the developing permanent tooth beneath it. RULE OF 4 AGE (in months) NUMBER OF TEETH ERUPTED SPECIFIC TEETH 7 4 Four mandibular incisors 11 8 Four maxillary incisors 15 12 Four first molars 19 16 Four canines 23 20 Four second molars DIFFERENCES ON GENERAL FEATURES FOR PRIMARY AND PERMANENT DENTITION PRIMARY PERMANENT NUMBER 20 Deciduous teeth, 5 in each quadrant 32 permanent teeth, 8 in each quadrant TYPES OF TEETH Generally small compared to their counterpart, Generally large compared to their except for deciduous molars which are larger counterpart, except for premolars which SIZE than their permanent counterpart are smaller than their deciduous counterpart White (due to a less mineralized enamel) Yellowish white, grey, brown Opaque = does not reflect the color of underlying (enamel is more mineralized and COLOR dentin translucent = reflect the color of underlying dentin) PLACEMENT IN Placed perpendicular in relation to the jaws Placed oblique in relation to the jaws THE JAW ©rjcadmd 12 ORAL ANATOMY – PRELIMINARY HANDOUTS ROOT Fully formed 1 year after eruption Fully formed 3 years after eruption FORMATION MORPHOLOGICAL DIFFERENCE FOR PRIMARY AND PERMANENT DENTITION PRIMARY PERMANENT CROWN MORPHOLOGY SHAPE More bulbous Less bulbous DIMENSION Wider mesiodistally compared to crown length Length of the crown is more compared with their mesiodistal width SURFACE Labial and buccal surfaces are flat above the cervical Facial, lingual/palatal surface are convex ridge up to the incisal surface MAMELONS Absent Present CINGULUM More prominent Less prominent CUSPS Short, sharp and pointed Less sharp OCCLUSAL SURFACE Shallow Deeper OCCLUSAL AREA Buccal & lingual/palatal surface converge occlusally = Wider buccolingually narrow buccolingually CONTACT AREA Small contact area placed more gingivally Large contact area and are placed either middle third or (PROXIMAL) at the junction of middle and incisal 3rd CERVICAL LINE Less curved More curved CERVICAL RIDGE Prominent, especially on the labial surface of anterior Less pronounced teeth and buccal & mesial surface of the molars CERVICAL Marked constriction, making the crown look more Less pronounced CONSTRICTION bulbous ROOT MORPHOLOGY LENGTH OF THE Shorter and slender Long and Strong ROOT CROWN:ROOT Roots of deciduous teeth are proportionally longer when The roots of the permanent teeth are not as long as the RATIO compared to crown size crown size Ideally = 2:3 ; Acceptable: 1:1 INCLINATION OF Slight labial inclination of 10° Do not show any labial inclination ROOT FURCATION Near the cervix of the tooth Level of furcation is about 3-4mm from the cervix of the tooth ROOT TRUNK Not distinct Long and distinct ROOT FLARE Flare beyond mesiodistal and buccolingual outline Do not flare and are well within the boundaries of the crown. PULP MORPHOLOGY PULP CHAMBER Large compared to the size of the crown Small compared to size of the crown ©rjcadmd 13 ORAL ANATOMY – PRELIMINARY HANDOUTS PULP HORN Extended more incisally/occlusally; placed close to the Not placed at a high level as in deciduous teeth enamel PULP CANAL Wider compared with the root width; more tortuous Narrow in comparison with root width ACCESSORY PULP More in number; and are more situated in the furcation Mostly seen in the apical area CANALS area HISTOLOGICAL DIFFERENCE FOR PRIMARY AND PERMANENT DENTITION PRIMARY PERMANENT ENAMEL Thin and uniform thickness, less calcified, Thick with varying thickness, more calcified, enamel rods inclined horizontally towards enamel rods incline apically towards enamel enamel surface surface DENTIN Thin and of variable thickness Thick and uniform thickness NEONATAL LINE Present on all deciduous teeth Present only on permanent mandibular 1st molar DEJ Scalloped Smooth CEMENTUM Thin Thick Crown is shorter relative to root DISTINCT FEATURE OF PRIMARY ANTERIOR TEETH length, roots are long in proportion to Bulges on the cervical third on the labial and lingual the crown length and are relatively surfaces The lingual bulge is seen as a relatively narrow mesiodistally large cingulum which occupies up to one-third of the cervico-incisal crown length and the labial bulge is seen as a prominent convex cervical ridge (proximal views). S-shaped o Prominent cervical ridges on the facial surfaces run mesiodistally in the cervical 3rd o The prominent lingual cingula seem to bulge and occupy about one third of the cervicoincisal length Roots bend labially (10°) in their apical third Roots of maxillary incisors bend (bow) lingually in the cervical third to half, whereas the mandibular incisors are straight in their cervical third (proximal views). PRIMARY MAXILLARY CENTRAL INCISOR ©rjcadmd 14 ORAL ANATOMY – PRELIMINARY HANDOUTS Wider mesiodistally than cervicoincisally Roughly square shaped Mesial outline = right angle Distal outline = obtuse angle Labial cingulum present on the crown Palatal outline is S-shaped (proximal aspect) o Due to prominent cingulum PRIMARY MANDIBULAR CENTRAL INCISOR Bilaterally symmetrical when viewed from the PRIMARY MAXILLARY LATERAL INCISOR facial and incisal Cervical outline = semilunar with convexity facing Has a distal developmental depression on the towards the apex root The cervicoincisal length of the lateral crown is greater than its mesiodistal width PRIMARY MAXILLARY CANINE Are about as wide mesiodistally as they are long incisogingivally (facial view) Diamond-shaped crowns from facial Cusp tip sharp, developed and centered PRIMARY MANDIBULAR LATERAL INCISOR Primary maxillary canines have their mesial cusp Similar to mandibular central incisor but larger ridge longer than the distal cusp ridge in all measurements except labiolingually Mesial proximal contact more cervical than the Prominent mesial cervical ridge = makes it distal easier to distinguish right and left side ©rjcadmd 15 ORAL ANATOMY – PRELIMINARY HANDOUTS PRIMARY MANDIBULAR CANINE PRIMARY MAXILLARY 1ST MOLAR Distal cusp ridge longer than on the mesial cusp Very prominent mesiobuccal cervical ridge ridge Most atypical of all molars Longer incisocervically and narrow mesiodistally H-shaped pit-groove pattern (facial views) No root trunk PRIMARY MAXILLARY 2ND MOLAR May have cusp of carabelli DISTINCT FEATURE OF PRIMARY POSTERIOR TEETH Widest primary Wider mesiodistally and shorter cervico- tooth occlusally (buccal view) (buccolingually) Primary 1st molars are smaller than primary 2nd molars Buccal cusps are not sharp Buccal cervical ridges are prominent with cervical lines curved more apically on the mesial PRIMARY MANDIBULAR 1ST MOLAR half of the buccal surface Does not resemble any other primary or Primary molar crowns have narrow chewing permanent tooth surface (occlusal Very low and prominent buccal cervical ridge table) Widest primary tooth (mesiodistally) The mesial marginal ridge is so well developed that it resembles a cusp No central fossa but has mesial and distal triangular fossa Both maxillary and mandibular 2nd primary molars resemble the maxillary and mandibular 1st permanent molars (Isomorphy) Primary maxillary molars have 3 roots Primary mandibular molars have 2 roots 1st MOLAR 2nd MOLAR ©rjcadmd 16 ORAL ANATOMY – PRELIMINARY HANDOUTS PRIMARY MANDIBULAR 2ND MOLAR Resembles the permanent mandibular 1st molar Differs with permanent mandibular 1st molar on the three buccal cusps which are nearly equal in size versus the permanent molars where the distal cusp is usually considerable smaller (occlusal view) References: Nelson, Stanley J. (2015). Wheeler’s Dental Anatomy, Physiology, and Occlusion 10th Ed. St. Louis, Missouri: Elsevier, Saunders. pp. 1-19, 21 – 41, 43 - 63 Scheid, Rickne C. (2017). Woelfel’s Dental Anatomy 9th Ed. Philadelphia: Wolters Kluwer. pp. 3 – 35, 164 – 188, Rajkumar, S., Ramya, R. (2017). Textbook of Oral Anatomy, Histology, Physiology and Tooth Morphology. 2nd ed., India: Walters Kluwer. pp. 3-12, 183 - 288 ©rjcadmd 17