Tooth Morphology the study of the form of

Tooth Morphology (the study of the form of teeth) 1. 2. 3. 4. Structure of teeth. Supporting structures. Deciduous tooth morphology. Secondary tooth morphology Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

Maxillary teeth • Supported by the maxillary bone • Belong to the maxillary arch Figure courtesy Hu-Friedy Quality Education for a Healthier Scotland

Mandibular teeth • Supported by the mandibular bone • Belong to the mandibular arch Figure courtesy Hu-Friedy Quality Education for a Healthier Scotland

Each arch is divided into a right and left quadrant Figure courtesy Hu-Friedy Quality Education for a Healthier Scotland

Types of teeth • Incisors • Canines Anterior teeth • Molars • Premolars Posterior teeth Quality Education for a Healthier Scotland

Incisors Figure courtesy Hu-Friedy • 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. Quality Education for a Healthier Scotland

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. Quality Education for a Healthier Scotland

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. Quality Education for a Healthier Scotland

Molars Figure courtesy Hu-Friedy • 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. Quality Education for a Healthier Scotland

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. Quality Education for a Healthier Scotland

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 • • Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

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. Quality Education for a Healthier Scotland

Dentine Figure courtesy Hu-Friedy • 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 Quality Education for a Healthier Scotland

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. Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

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. Quality Education for a Healthier Scotland

Periodontal tissues Support and attach the teeth to their bony sockets Quality Education for a Healthier Scotland

Attachment tissues Periodontal ligament Cementum Alveolar bone Diagram courtesy Oral-B Quality Education for a Healthier Scotland

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. Quality Education for a Healthier Scotland

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. Quality Education for a Healthier Scotland

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. Quality Education for a Healthier Scotland

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 2 mm 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. Quality Education for a Healthier Scotland

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EXERCISE Quality Education for a Healthier Scotland

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Eruption Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

Deciduous dentition Figure courtesy Hu-Friedy Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

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. Quality Education for a Healthier Scotland

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. Quality Education for a Healthier Scotland

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 2 nd molars resemble miniature 1 st permanent molars; but the shape of deciduous 1 st molars is much less typical, having a pronounced mesio-buccal bulge. Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

Permanent dentition Figure courtesy Hu-Friedy Quality Education for a Healthier Scotland

Permanent dentition eruption ages Tooth First molars Central incisors Lateral incisors Canines First premolars Second molars Third molars Eruption age 6 to 7 years 6 to 8 years 7 - 9 years 9 to 11 years 10 to 12 years 12 to 13 years 17 to 22 years Quality Education for a Healthier Scotland

Exercise Quality Education for a Healthier Scotland

What Is the Approximate Age of These Patients? Quality Education for a Healthier Scotland

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CHARTING Quality Education for a Healthier Scotland

Tooth surfaces-posterior teeth Figure courtesy Hu-Friedy • Mesial – nearest the midline • Distal – furthest from the midline • Lingual - facing the tongue • Buccal – facing the cheek • Occlusal – chewing surface Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

Tooth identification There is a convention for naming the teeth which must be followed Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

EXERCISE Quality Education for a Healthier Scotland

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Palmer notation Permanent teeth Figure courtesy Hu-Friedy Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

Palmer notation Identification Deciduous tooth Symbol assigned Central incisor A Lateral incisor B Canine C First molar D Second molar E Quality Education for a Healthier Scotland

Palmer notation Deciduous teeth Figure courtesy Hu-Friedy Quality Education for a Healthier Scotland

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 Quality Education for a Healthier Scotland

EXERCISE Quality Education for a Healthier Scotland

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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 Quality Education for a Healthier Scotland

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

FDI notation system Permanent teeth Figure courtesy Hu-Friedy Quality Education for a Healthier Scotland

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

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 Quality Education for a Healthier Scotland

FDI Identification Deciduous tooth Number Assigned Central incisor 1 Lateral incisor 2 Canine 3 First molar 4 Second molar 5 Quality Education for a Healthier Scotland

FDI notation system Deciduous teeth Figure courtesy Hu-Friedy Quality Education for a Healthier Scotland

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

EXCERCISE Quality Education for a Healthier Scotland

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