Tooth Morphology (the study of the form of teeth) Structure of teeth. Supporting structures. Deciduous tooth morphology. Secondary tooth morphology

Teeth General arrangement of teeth is called the dentition Primary dentition Contains the deciduous teeth Secondary dentition Contains the permanent teeth Mixed dentition Contains some deciduous and some permanent teeth Mixed dentition sometimes called ugly ducking stage

Maxillary teeth Supported by the maxillary bone Belong to the maxillary arch What is the bone called that supports the teeth? What is special about it? Figure courtesy Hu-Friedy

Mandibular teeth Supported by the mandibular bone Belong to the mandibular arch Give me the names of parts of the mandible? Ramus Mandibular body Angle of the mandile Coronoid process Condylar process Give me the names of the 2 foramen in the mandible Mental Mandibular Figure courtesy Hu-Friedy

Each arch is divided into a right and left quadrant Figure courtesy Hu-Friedy

Types of teeth Incisors Canines Molars Premolars Anterior teeth Posterior teeth

Incisors Designed to bite or cut food The biting surface is called the incisal edge. Central incisor larger than lateral incisor. Flattened crown with one root. Upper central incisor is largest of all incisors. Figure courtesy Hu-Friedy

Canines Designed to cut and tear food Upper canines larger than lowers. Large conical crown with pointed incisal edge and one long root. Upper canines have longest of all roots. Canines known as eye teeth

Premolars Used for tearing and chewing food All have two cusps, equal size in uppers, smaller lingual cusp in lowers. Upper first premolar has two roots (buccal and palatal), all others have one root. Upper premolars 2 roots

Molars All have large occlusal surface for grinding and chewing food. All upper molars have three roots (palatal, mesiobuccal and distobuccal) All lower molars have two roots (mesial and distal). Upper first molar has five cusps, fifth one called ‘cusp of carabelli’. Lower first molar has five cusps, three buccal and two lingual. All other molars have four cusps. Roots in third molars vary in number, uppers are often fused together. Figure courtesy Hu-Friedy

Occlusion In a normal mouth all incisal edges and cusps of upper and lower teeth interlock to give a stable bite (occlusion). The upper arch is usually wider so that the lower teeth bite into the middle of the upper teeth, or onto the cingulum of the incisors and canines.

Parts of the teeth Each tooth consists of a crown and root The crown is covered by enamel The root is covered by cementum The crown and root are joined at the cementenamel junction The cervical line separates the crown and root

Enamel Hardest tissue in the body Covers the crown Thickest over the tips of the crown Thinnest where crown meets the root Colour is determined by thickness Figure courtesy Hu-Friedy

Enamel It is made up of 96% inorganic crystals arranged as prisms Main mineral crystals are hydroxyapatite. Junction where enamel meets dentine is called the amelodentinal junction. Contains no nerves or blood vessels and therefore cannot experience sensitivity. Non-living tissue which cannot grow or repair itself, but can remineralise after acid attack. Can exchange minerals, especially fluoride, to form fluorapatite crystal which make the enamel surface harder still and more resistant to acid attack.

Dentine Forms the bulk of the crown and root of the teeth Covered by enamel in the crown Covered by cementum in the root Living tissue Receives nutrition from dentinal tubules running from the pulp Tubules are involved with toothache Figure courtesy Hu-Friedy

Dentine It is up to 80% inorganic. It is composed of hollow tubules containing fibrils, which are sensory endings from the cells forming the dentine. It is therefore a living tissue, and can transmit sensitivity. It is formed by ondontoblast cells, which lie at the edge of the pulp chamber. It can repair itself by producing secondary dentine. Secondary dentine also forms as part of the natural ageing process. Caries progresses rapidly through dentine because of its hollow nature.

Cementum The cementum is the layer covering dentine of the root. It normally lies beneath the gingiva. It allows attachment of the tooth to the supporting structure of the periodontal ligament. Calcium Hydroxyapatite Similar chemically to bone Figure courtesy Hu-Friedy

Pulp Chamber Pulp Canals Pulp is the soft tissue within the tooth structure. Surrounded by dentine Consists of connective tissue, blood vessels and nerves Odontoblasts present on the wall of the pulp chamber Figure courtesy Hu-Friedy

Pulp It allows the tooth to feel hot, cold, touch, pain by stimulation of fibrils in dentine. Vessels enter the tooth through the apical foramen, at the end of each root apex. These tissues are enclosed within the pulp chamber of the tooth. Chamber is lined by ondontoblast cells. Gradual formation of secondary dentine with age causes pulp chamber to decrease in size and become narrower.

Support and attach the teeth to their bony sockets Periodontal tissues Support and attach the teeth to their bony sockets

Attachment tissues Periodontal ligament Cementum Alveolar bone Known as peridontium 4 parts Tooth Alveolar bone Periodontal ligament Cementum Alveolar bone Diagram courtesy Oral-B

Periodontal Ligament This is a specialised fibrous tissue which attaches the teeth to the alveolar bone and surrounding tissues. Fibres are made up of protein called collagen. Acts as a shock absorber when tooth undergoes normal chewing movements, so that the tooth can bounce a little in its socket and not fracture. Destruction of periodontal ligament occurs during periodontal disease.

Alveolar bone The bony extensions of the maxilla and mandible, where the teeth are formed and from where they erupt into the mouth. Special bone found only in the jaws. Sole purpose is to support the teeth during their lifetime. When teeth are extracted, alveolar bone gradually resorbs away. Outer layer is hard compact bone, with the surface being called the lamina dura. Inner layer is cancellous bone, sponge like in appearance to allow blood vessels and nerves to run through. Destruction of the alveolar bone can occur during periodontal disease.

Cementum The cementum is the layer covering dentine of the root. It normally lies beneath the gingivae. It allows attachment of the tooth to the supporting structure of the periodontal ligament.

Gingivae This is the correct term for the gums. In health they are light pink in colour with a stippled (orange peel) surface. Form a 2mm crevice (gingival crevice) around the necks of each tooth, above periodontal ligament. Gingivitis occurs when this area becomes inflamed. Inflamed gingivae are red and shiny, with a swollen appearance.

EXERCISE

Enamel Dentine Pulp Cementum Periodontal ligament Lamina Dura (Compact bone) Cancellous Bone (spongy bone)

Eruption

Eruption Two sets of teeth develop in a person’s lifetime The deciduous dentition contains 20 teeth The permanent dentition contains 32 teeth And for a period of time a child will have a mixed dentition Containing some deciduous teeth and some permanent teeth

Deciduous dentition The first teeth to appear are the deciduous incisor teeth at about 6 months The last teeth to appear are the deciduous second molars at 2 ½ years

Deciduous dentition Figure courtesy Hu-Friedy

Deciduous dentition eruption ages Tooth Eruption age Central incisors 6 to 8 months Lateral incisors 7 to 9 months First molars 12 to 16 months Canines 16 to 21 months Second molars 21 to 30 months a-6 months b- 8 months c- 18 months d- 12 months e- 24 months

Deciduous Teeth Deciduous teeth in general resemble their corresponding permanent teeth but there are some important differences. Deciduous teeth are much smaller. There is adequate space so crowding is uncommon. Deciduous crowns are whiter. Pulp chambers of deciduous teeth are relatively larger, their enamel is much thinner.

Deciduous Teeth Deciduous incisors and canines are smaller versions of their permanent successors. Deciduous molars have the same number of roots as permanent molars but differ in other respects.

Deciduous Teeth The crowns of deciduous molars are more bulbous. To provide space for the developing premolar, the roots of deciduous molars are more divergent than those of permanent molars. Deciduous 2nd molars resemble miniature 1st permanent molars; but the shape of deciduous 1st molars is much less typical, having a pronounced mesio-buccal bulge.

Permanent dentition The permanent teeth replace the deciduous teeth The first permanent teeth to appear are the mandibular first molars These teeth erupt behind the deciduous second molars The next permanent teeth to erupt are the central and lateral incisors

Permanent dentition Figure courtesy Hu-Friedy

Permanent dentition eruption ages Tooth Eruption age First molars 6 to 7 years Central incisors 6 to 8 years Lateral incisors 7- 9 years Canines 9 to 11 years First premolars 10 to 12 years Second premolars Second molars 12 to 13 years Third molars 17 to 22 years These are approx ages An easy way to work out eruption dates Lowers Uppers 1-7 2-8 3-9 3-11 4-10 4-9 5-11 5-10 6-6 7-12 8-18

Exercise

What Is the Approximate Age of These Patients?

12 years All permanent teeth erupted except the third molars

8-10 years Canines not quite erupted No premolars yet 7’s not in Lower right e present but you can see roots starting to resorb.

7-8 years 6’s erupted Central’s and laterals erupted e’s still present

CHARTING

Tooth surfaces-posterior teeth Mesial – nearest the midline Distal – furthest from the midline Lingual - facing the tongue Buccal – facing the cheek Occlusal – chewing surface Figure courtesy Hu-Friedy

Tooth surfaces-anterior teeth Labial – facing the lip Mesial – nearest the midline Distal – furthest from the midline Lingual - facing the tongue Incisal edge – biting surface of anterior teeth Figure courtesy Hu-Friedy

There is a convention for naming the teeth which must be followed Tooth identification There is a convention for naming the teeth which must be followed

The tooth is identified by The dentition – permanent or deciduous The arch – maxillary or mandibular The quadrant – right or left side of the mouth The tooth type – incisor, canine, premolar or molar

EXERCISE

Palmer notation Permanent teeth Figure courtesy Hu-Friedy

Examples of palmer notation Palmer notation Tooth description Permanent maxillary right second premolar Permanent maxillary left third molar Permanent mandibular left lateral incisor Permanent mandibular right canine Difficult to recreate on computer so sometime UR UL LL and LR use to define quadrant

Palmer notation system Deciduous teeth Assigns a letter to the deciduous tooth depending on its position relative to the midline Central incisors are closest to the midline and are given the letter A The second molars are furthest and are given the letter E

Palmer notation Identification Deciduous tooth Deciduous tooth Symbol assigned Central incisor A Lateral incisor B Canine C First molar D Second molar E

Palmer notation Deciduous teeth Figure courtesy Hu-Friedy

Palmer notation Deciduous teeth Palmer Notation Tooth description Deciduous maxillary right second molar Deciduous maxillary left first molar Deciduous mandibular left lateral incisor Deciduous mandibular right canine

EXERCISE Palmers charting

FDI notation system – Permanent teeth Uses a two-digit number to identify each tooth The first digit identifies the quadrant The permanent quadrants are numbered from 1 through to 4 The second digit identifies the tooth The permanent teeth are numbered from 1 through to 8

FDI- Identification Permanent tooth Permanent tooth Number assigned Central incisor 1 Lateral incisor 2 Canine 3 First premolar 4 Second premolar 5 First molar 6 Second molar 7 Third molar 8

FDI notation system Permanent teeth Figure courtesy Hu-Friedy

Examples of FDI notation Notation Tooth description 11 Permanent maxillary right central incisor 16 Permanent maxillary right first molar 23 Permanent maxillary left canine 28 Permanent maxillary left third molar 34 Permanent mandibular left first premolar 37 Permanent mandibular left second molar 42 Permanent mandibular right lateral incisor 45 Permanent mandibular right second permolar

FDI notation system Deciduous teeth Uses a two-digit number to identify each tooth The first digit identifies the quadrant The deciduous quadrants are numbered from 5 through to 8 The second digit identifies the tooth The deciduous teeth are numbered from 1 through to 5

FDI Identification Deciduous tooth Deciduous tooth Number Assigned Central incisor 1 Lateral incisor 2 Canine 3 First molar 4 Second molar 5 Not letters but numbers 1-5

FDI notation system Deciduous teeth Figure courtesy Hu-Friedy

Examples of FDI notation Notation Tooth description 51 Deciduous maxillary right central incisor 54 Deciduous maxillary right first molar 63 Deciduous maxillary left canine 65 Deciduous maxillary left second molar 74 Deciduous mandibular left first molar 75 Deciduous mandibular left second molar 82 Deciduous mandibular right lateral incisor 81 Deciduous mandibular right central incisor

EXCERCISE