ORAL ANATOMY ORAL HISTOLOGY Diphyodont Polyphyodont Hetero dont

ORAL ANATOMY & ORAL HISTOLOGY

• Diphyodont • Polyphyodont

• Hetero dont • Homodont MAN Diphyodont - Heterodont

• “Deciduous” Latin means “FALL OFF” • “Milk teeth” – “Temporary teeth” – “Baby tooth”

• 6 months – 2 years • Mixed dentition period 6 – 12 years • Permanent teeth – 6 yrs to 21 yrs

• Maxillary – upper jaw • Mandibular – lower jaw

Functions of teeth • Mastication (Chewing) • Phonation (Speech) • Esthetics (Appearance) • Self protection

Parts of a Tooth – Crown – Root R O O T Cervix / neck CROW N

MOLAR TOOTH CROWN R O O T

Anatomical Crown – covered by enamel Clinical Crown – visible in the oral cavity

Anatomical Root – covered by Cementum Clinical Root – Covered by gingiva

Types of Teeth: ØIncisors: Have a sharp thin edge cutting. ØCanines: cutting and tearing. ØPremolars: have two cusps tearing and crushing. ØMolars: Have 4 to 5 cusps and a broad surface grinding and chewing

Structure of Tooth and Supporting Structures

Enamel • Outermost covering • Hardest • Yellowish - grayish white • Non-living tissue

Dentin • Hard – connective tissue • Bulk of the tooth • Covered by Enamel – Crown Cementum - Root

Cementum - Covers Root - Yellowish - Anchorage

Pulp • Soft connective tissue • Central portion • Nerves and blood vessels • Cells, fibers, intercellular substance

Supporting structures of teeth • Alveolar sockets • Periodontal ligament (collagen fibers)

Junctions • Cemento – Enamel Junction • Dentino – Enamel Junction • Cemento – Dentinal Junction

Types of Dentition 1. Deciduous Teeth 2. Permanent Teeth

Deciduous teeth • Primary teeth • Baby teeth • Milk teeth • Lacteal dentition

Dental formula 2 1 2 2

Permanent teeth • Secondary dentition 1. Successor / Succedaneous teeth 2. Non-successor / Non-succedaneous teeth

Formulae for teeth • I – Incisor , C – Canine , P – Premolar , M – Molar

2 I 1 C 2 P 3 M

Dental formula 2 1 2 3

• Dental formula for Deciduous teeth • I 2 / 2 C 1/ 1 M 2 / 2 = 10 2 x 10 = 20 • Dental formula for Permanent teeth • I 2/2 , C 1/1 , P 2/2 , M 3/3 = 16 2 x 16 = 32

Position of teeth Anterior Teeth Posterior Teeth

Facial Surface 1. Labial 2. Buccal

Lingual / Palatal 1. Palatal 2. Lingual

Incisal / Occlusal 1. Incisal 2. Occlusal

Proximal surface 1. Mesial 2. Distal

Tooth numbering system • Recording data • Communication

• 1. Zsigmondy / Palmer notation • 2. Universal system • 3. FDI ( Federation Dentaire Internationale)

Zsigmondy - Palmer notation / Grid system • Adolph Zsigmondy in 1861 • Arches are divided quadrants • Deciduous teeth Right EDCBA ABCDE Left

Permanent teeth • Central incisor numbered 1 through 8 in each arch Right left 87654321 12345678

• Advantages – Many countries use this system – Simple • Disadvantage – More Chances of error in noting sides

Universal system – Deciduous teeth • Parriedt 1882 • Deciduous teeth • Maxillary teeth beginning with right second molar use the letter A through J , for mandibular teeth K through T Right Left side ABCDE F G H I J TSRQP O NMLK

Universal system – Permanent teeth • Right III Maxillary teeth numbered as 1 through 16 • Mandibular left III molar 17 through 32 Right 1 2 3 4 5 6 7 8 Left 9 10 11 12 13 14 15 16 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17

• Disadvantage – Needs more practice for quick & correct notation

FDI system • Two digit / ISO 3950 notation • adopted by WHO

FDI system – Permanent teeth • Permanent dentition – 1 to 4 Upper right Upper left 18 17 16 15 14 13 12 11 21 22 23 24 25 26 27 28 48 47 46 45 44 43 42 41 31 32 33 34 35 36 37 38

FDI system – Primary teeth • • 5 - maxillary right 6 - maxillary left 7 - mandibular left 8 - mandibular left Left Right 55 54 53 52 51 61 62 63 64 65 85 84 83 82 81 71 72 73 74 75

• Advantages – Accepted by WHO – Less chances of error – Easy to follow

Trait Categories • Set trait – Deciduous teeth – Permanent teeth

• Arch trait – Maxillary – Mandibular

• Class traits – Incisors – Canines – Premolars – Molars

• Type trait • Incisors – Central / Lateral • Premolars – 1 st / 2 nd Premolar • Molars – 1 st / 2 nd / 3 rd Molar

Descriptive Division of the Tooth

Division of Crown into thirds – Facial / Lingual surface • Cervical third • Middle third • Incisal / Occlusal third

– Facial / Lingual surface • Mesial third • Middle third • Distal third

– Mesial / Distal surface • Labial third • Middle third • Lingual third

– Mesial / Distal surface • Cervical third • Middle third • Incisal / Occlusal third

Division of root into thirds • Labial / Lingual & Mesial / Distal surfaces – Cervical third – Middle third – Apical third

– Mesial / Distal surface • Facial third • Middle third • Lingual third

– Facial / Lingual surface • Mesial third • Middle third • Distal third

Line angles • Junction between two surfaces that meet each other

• Posterior teeth – 8 line angles – Mesio buccal – Disto buccal – Mesio lingual – Disto lingual – Mesio occlusal – Disto occlusal – Bucco occlusal – Linguo occlusal • Anterior teeth – 6 line angles – Mesio labial – Disto labial – Mesio lingual – Disto lingual – Labio incisal – Linguo incisal

Point angles • Point where three surfaces meet and are named by joining the name of those three surfaces which meet.

• Both anterior and posterior 4 point angles – Mesio-bucco-occlusal – Mesio-linguo-occlusal – Disto-bucco-occlusal – Disto-linguo-occlusal

Descriptive terms • Cusp: It’s a point, peak, rounded elevation on the crown portion of a tooth making up a divisional part of the occlusal surface.

• Occlusal surfaces • Each cusp – representative of a center of calcification (a lobe) • Each cusp 2 cusp slopes Mesial cusp slope and Distal cusp slope – Canines 1 cusp – Premolars 2 cusps – Molars 4 / 5 cusps

Tubercle • It is a smaller elevation on some portion of the crown produced by an extra formation of enamel – Tubercle of Carabelli

Cingulum • Bulge or Elevation on the lingual surface of incisors or canines

Ridge • Linear elevation present on the surface of the tooth • Depending on location – Labial ridge – Lingual ridge – Buccal ridge – Incisal ridge – Marginal ridge – Cuspal ridge

1. Marginal ridge • Rounded borders of enamel that form margins of anterior / posterior teeth • Anterior teeth boundary of lingual surface • Posterior teeth boundary of occlusal surface

2. Triangular ridge • Ridges that run from the tips of the cusps of premolars and molars toward the centre of the occlusal surfaces

3. Transverse ridges • Formed by 2 triangular ridges (buccal and lingual ) • Join transversely across the occlusal surfaces of the posterior teeth

4. Oblique ridge • Ridge, that runs obliquely on the occlusal surfaces • Union of triangular ridge of the disto-buccal cusp and the distal ridge of the mesio-palatal cusp

5. Labial Ridge • Vertical • Cervico-incisal direction • Labial surface of canine

6. Lingual Ridge • Vertical • Cervico-incisal direction • Lingual surface • Divides lingual fossa into Mesial and Distal

7. Buccal Ridge • Vertical • Cervico-occlusal direction (premolars) • Prominent 1 st Premolars

8. Cervical Ridge • Horizontal • Mesio-distal direction • Cervical one-third of the buccal surface

9. Cusp ridges • Mesial and Distal slopes of the cusps

10. Linguo-Incisal Ridge • Horizontally Mesio-distal direction • Incisal one-third (Lingual surface) of upper incisors

Fossa • Irregular depression or concavity found on the lingual surface of anterior teeth or occlusal surface of posterior tooth

• Fossae can be 1. Lingual fossa 2. Central fossa 3. Distal fossa 4. Triangular fossa

Lingual fossa • lingual surface of anterior teeth, • bounded by marginal ridges, cingulum and linguo-incisal ridge. • canines are divided in to two by lingual ridge.

• A central fossa: is found on the occlusal surface of a molars which are formed by the converging of ridges terminating at a central point in the bottom of a depression where there is a junction of grooves.

• Triangular fossae -molars and premolars on the occlusal surfaces just inside the marginal ridges. • two triangular fossae including mesial triangular fossa

• A sulcus is a broad linear depression or valley on the surface of a posterior tooth. • Sulcus is the area between ridges and cusps, the inclines of which meet at an angle to form a groove called as developmental groove. •

• A groove is a linear depression or a line present at the deepest part of the sulcus. • developmental grooves / supplemental grooves

• Developmental grooves • sharply defined, narrow and linear depression seen separating major portions of a tooth developing from different lobes.

• A supplemental groove is a small irregularly placed shallow groove which is less distinct • not found between major portions of a tooth.

• Pits pinpoint depressions located at the junction of developmental grooves or at terminals of those grooves. • Pits - found at the deepest part of fossae,

• Fissure is a cleft or ditch formed at the bottom of a developmental groove.

Lobe • Primary sections of formation in the development of the crown

Deciduous • Incisors 1 lobe • 2 nd Molar 5 lobes

Permanent teeth • Anteriors 4 lobes • Premolars 4 lobes • Molars number of lobes = number of cusps

Mamelons • 3 protruberances found on the incisal ridges of newly erupted incisor teeth

• Root trunk –the undivided cervical portion of the root of multirooted teeth.

• Furcation is the division of the root of the multirooted teeth. • When the root is dividing in to two it is referred to as bifurcation and when three, trifurcation.

• Apical and accessory foramen are small openings found at the apical region of root through

• Contact point or contact areas • Contact areas are the places on the proximal surfaces of tooth crowns where a tooth touches the adjacent tooth in the same arch,

• Functions of contact • Contact area helps to prevent food wedging during mastication, • maintain the arch length,

• Contours are curvatures that are seen on are the cervical or middle third on the facial or lingual aspect of all the teeth in dental arch.

• Height of contour or crest of curvature is an imaginary curved line encircling a tooth at its greatest bulge.

• Embrasures (spillways) are triangular or Vshaped spaces seen facial, lingual or occlusal to the contact areas.

• Functions of embrasures • allow food to be forced away from contact areas and thus keep food from being packed between them. • help to dissipate and reduce occlusal forces. • protecting the gingiva from undue trauma.

Chronology and Sequence of Eruption

Crown and Root • Crown is covered by enamel • Root portion covered by cementum • Crown and root will join with CEJ • Four tooth tissue are there Enamel , Dentin , Cementum- hard tissue • Pulp – soft tissue • Crown of incisors – Incisal ridge or edge • Single cusp – canine

• Two or more cusp – PM and molars • Root – single – incisors and Canine • Multiple roots – PM and Molars • Portion of the jaw serving as support for the tooth – Alveolar process • Soft tissue which covers the cervical 1/3 of the tooth – Gingiva or Gums

Surfaces and Ridges • Crowns of the teeth will have surfaces • Surfaces named according to their position – • Labial , Lingual , Mesial , distal and Incisal • Four teeth will have mesial surface that contact each other named as Maxillary and Mandibular incisors • Contact area – area of the mesial and distal surface of a tooth that touches its neighbor in the arch

Other land marks • • Cusp Tubercle Cingulum Ridge Marginal ridge Triangular ridge Transverse ridge Oblique ridge • • • Fossa Sulcus Developmental groove Supplemental groove Pit lobe

• Cusp – • Elevation or mound on the crown portion of a tooth • Tubercle – • Smaller elevation on some portion of the crown produced by an extra formation of the enamel • Cingulum – • It is also called as girdle – lingual lobe of an anterior tooth and makeup the bulk of the cervical third of the lingual surface at the cervical one third

• Ridge – • Linear elevation on the surface of a tooth and named according to location – Buccal , Incisal or marginal ridge • Marginal ridges – • Rounded border of the enamel that form the mesial and distal margins of the occlusal surface of the PM and molars • Mesial and distal margins of the lingual surfaces of the incisors and canines

• Triangular ridges – • It descends from the tip of the cusps of posterior teeth towards the central part of the occlusal surface • Transverse ridge – • buccal and lingual triangular ridges joins • It form by union of two triangular ridges transversely crossing the surface of a posterior tooth

• Oblique ridge – • It runs obliquely crossing the occlusal surface of maxillary molars • Union of the triangular ridge of the distobuccal cusp and distal cusp ridge of the mesiolingual cusp

• Fossa – • Irregular depression or concavity • Lingual fossae – lingual surface of incisors • Central fossae – convergence of ridges terminating at a central point in the bottom of the depression where a junction of grooves occur • Triangular fossae – occlusal surface of posterior teeth

• Sulcus – • Long depression or valley in the surface of a tooth between ridges and cusps, the inclines of which meet at an angle • Developmental depression – • Shallow groove or line between the primary parts of the crown and root • Supplemental groove – less distinct , shallow linear depression on the occlusal surface of a tooth • Buccal and lingual developmental grooves – found on the buccal and lingual surface of posterior teeth

• Pits – • Small pinpoint depression located at the junction of developmental grooves • Central pits – landmark of the central fossa of molars where developmental grooves are join • Lobe – • Primary section of formation in the development of crown

• Mamelon – • Any one of the three rounded protuberance found on the Incisal ridges of newly erupted incisor teeth • Roots – • Single or multiple

Division into thirds • Purpose of description crown and root divided into three portions • Crown – • Labial – cervical, middle , Incisal / Distal , Middle , Mesial • Mesial aspect – Labial , Middle , Lingual • Posterior teeth – cervical , middle and occlusal • Root – cervical , Middle , Apical

Line angles • Junction of two surfaces ( Ex – mesial and Labial) – Mesioincisal line angle • Line angles of the anterior teeth • Mesiolabial , • Distolingual , • Distolabial , • Labioincisal , • Mesiolingual , • Linguo incisal

Line angles of the Posterior teeth • • Mesiobuccal Distobuccal Mesiolingual Distolingual Mesioocclusal Distoocclusal Bucco occlusal Lingual occlusal

Point angles • Junction of three surfaces • Point angles of the anterior teeth • Mesiolabial incisal • Mesiolinguoincisal • Distolabial incisal • distolinguoincisal

• Point angles of the posterior teeth • Mesiobuccaoocclusal • Mesiolinguo occlusal • Distobucco occlusal • Distolingual occlusal

Methods of Measuring of tooth