Difference between revisions of "Tooth Development"

Revision as of 14:15, 3 September 2010

Introduction

Gaboon Viper - Copyright RVC

Teeth develop differently in different regions of the mouth in most species, a process called heterodonty. In some animals teeth develop identically in different regions of the mouth, a process called homodonty. Different species will have varying numbers of teeth and different shapes depending largely on diet.

Not all species possess teeth and there is huge variation in dental formulae between the species that have teeth.

Teeth are mainly used for mastication - chewing and grinding food particles, but are also used for seizing prey and tearing.

The occlusion surface is where opposing teeth touch. The contact surface is where adjacent teeth touch.

Tooth Development

Tooth Development Histology - Copyright RVC 2008

1. Focal thickening of oral epithelium on medial aspect of the labiogingival groove forms the dental lamina

2. Mesenchyme under each laminae condenses

3. Dental lamina invaginates to form the dental bud

4. Dental bud expands and branches to become the enamel organ

5. Enamel organ surrounds the neural crest cell derived dental papilla

6. Combination of enamel organ and dental papillae forms the deciduous tooth

7. Small mass of cells bud off the dental lamina forming the primordium of the permanent tooth which continues development

8. Inner cell layer of enamel organ (from oral epithelium) differentiates into ameloblasts

9. Neighbouring cells in dental papillae (from neural crest cells) differentiate into odontoblasts

10. Dentine surrounds pulp to produce root of tooth

11. Epithelial cells near the distal tooth form cementoblasts, secreting cementum around the tooth root

Reciprocal inductive interaction between the oral epithelium and mesenchyme precursors

Mesenchyme forms the tooth. It has labile differentiative properties but stabile morphogenic properties.

Tooth formation starts at the crown and progresses towards the root

Tooth does not aquire full length until the crown has emerged

Tooth growth is appositional

Eruption

Deciduous Tooth

Occurs after the crown has fully formed (prior to complete root formation)

Provides the space required for root completion

Epithelial covering is continuous with gums after eruption

Erosion (wear) removes epithelium

'Toothless' gene stops eruption

Permanent Tooth

Migrates into socket of deciduous tooth on lingual side

Increases pressure on deciduous tooth by increased growth

Resorption of deciduous tooth root leads to loosening of deciduous tooth

Shedding of deciduous tooth

Permanent tooth replaces deciduous tooth

Premature loss of deciduous tooth leads to disorganised (non-occluding) permanent teeth

Test yourself with the Teeth and Gingiva Flashcards

Teeth & Gingiva Flashcards

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-{{OpenPagesTop}}
 ==Introduction==
-[[Image:Gaboon Viper Skull.jpg|thumb|right|250px|Gaboon Viper - Copyright RVC]]
+[[Image:Gaboon Viper Skull.jpg|thumb|right|150px|Gaboon Viper - Copyright RVC]]
-Teeth develop differently in different regions of the mouth in most species, a process called '''heterodonty'''. In some animals, teeth develop identically in different regions of the mouth, a process called '''homodonty'''. Different species will have varying numbers of teeth and different shapes depending largely on their diet. Not all species possess teeth and there is huge variation in dental formulae between the species that have teeth. Teeth are mainly used for [[Mastication|mastication]] - chewing and grinding food particles, but are also used for seizing prey and tearing. The '''occlusion surface''' is where opposing teeth touch. The contact surface is where adjacent teeth touch.
+Teeth develop differently in different regions of the mouth in most species, a process called heterodonty. In some animals teeth develop identically in different regions of the mouth, a process called homodonty. Different species will have varying numbers of teeth and different shapes depending largely on diet.
+Not all species possess teeth and there is huge variation in dental formulae between the species that have teeth.
+Teeth are mainly used for [[Mastication|mastication]] - chewing and grinding food particles, but are also used for seizing prey and tearing.
+The occlusion surface is where opposing teeth touch. The contact surface is where adjacent teeth touch.
 ==Tooth Development==
-[[Image:Tooth Development Histology.jpg|thumb|right|250px|Tooth Development Histology - Copyright RVC 2008]]
+[[Image:Tooth Development Histology.jpg|thumb|right|150px|Tooth Development Histology - Copyright RVC 2008]]
-Tooth development occurs in the following stages;
+. Focal thickening of oral epithelium on medial aspect of the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology#Labiogingival groove|labiogingival groove]] forms the dental lamina
+. Mesenchyme under each laminae condenses
+. Dental lamina invaginates to form the dental bud
+. Dental bud expands and branches to become the enamel organ
+. Enamel organ surrounds the neural crest cell derived dental papilla
+. Combination of enamel organ and dental papillae forms the deciduous tooth
+. Small mass of cells bud off the dental lamina forming the primordium of the permanent tooth which continues development
+. Inner cell layer of enamel organ (from oral epithelium) differentiates into [[Ameloblasts|ameloblasts]]
+. Neighbouring cells in dental papillae (from neural crest cells) differentiate into [[Odontoblasts - Anatomy & Physiology|odontoblasts]]
+. Dentine surrounds [[Pulp - Anatomy & Physiology|pulp]] to produce [[Root - Anatomy & Physiology|root]] of tooth
+. Epithelial cells near the distal tooth form [[Cementoblasts - Anatomy & Physiology|cementoblasts]], secreting [[Cementum - Anatomy & Physiology|cementum]] around the tooth [[Root - Anatomy & Physiology|root]]
+*Reciprocal inductive interaction between the oral epithelium and mesenchyme precursors
+*Mesenchyme forms the tooth. It has labile differentiative properties but stabile morphogenic properties.
+*Tooth formation starts at the [[Crown|crown]] and progresses towards the [[Root - Anatomy & Physiology|root]]
+*Tooth does not aquire full length until the [[Crown|crown]] has emerged
+*Tooth growth is appositional
+==Eruption==
+===Deciduous Tooth===
-. Focal thickening of oral epithelium on the medial aspect of the [[Gingiva#Labiogingival groove|labiogingival groove]] forms the dental lamina.
+*Occurs after the [[Crown|crown]] has fully formed (prior to complete [[Root - Anatomy & Physiology|root]] formation)
-. The mesenchyme under each laminae condenses.
+*Provides the space required for [[Root - Anatomy & Physiology|root]] completion
-. The dental lamina invaginates to form the dental bud.
+*Epithelial covering is continuous with gums after eruption
-. The dental bud expands and branches to become the enamel organ.
+*Erosion (wear) removes epithelium
-. The enamel organ surrounds the neural crest cell derived, dental papilla.
+*'Toothless' gene stops eruption
-. The combination of the enamel organ and dental papillae forms the deciduous tooth.
+[[Image:Tooth Radiograph.jpg|thumb|right|150px|Tooth Radiograph - Copyright Nottingham 2008]]
+===Permanent Tooth===
-. Small mass of cells bud off the dental lamina forming the primordium of the permanent tooth which continues development.
+*Migrates into socket of deciduous tooth on lingual side
-. The inner cell layer of enamel organ (from oral epithelium) differentiates into [[Tooth - Anatomy & Physiology#Ameloblasts|ameloblasts]].
+*Increases pressure on deciduous tooth by increased growth
-. Neighbouring cells in the dental papillae (from neural crest cells) differentiate into [[Tooth - Anatomy & Physiology#Odontoblasts|odontoblasts]].
+*Resorption of deciduous tooth root leads to loosening of deciduous tooth
-. Dentine surrounds [[Tooth - Anatomy & Physiology#Pulp|pulp]] to produce the [[Tooth - Anatomy & Physiology#Root|root]] of the tooth.
+*Shedding of deciduous tooth
-. Epithelial cells near the distal tooth form [[Tooth - Anatomy & Physiology#Cementoblasts|cementoblasts]], secreting [[Tooth - Anatomy & Physiology#Cementum|cementum]] around the tooth [[Tooth - Anatomy & Physiology#Root|root]].
+*Permanent tooth replaces deciduous tooth
-There is a reciprocal inductive interaction between the oral epithelium and mesenchyme precursors. The mesenchyme forms the tooth, it has labile differentiative properties but stable morphogenic properties. Tooth formation starts at the [[Tooth - Anatomy & Physiology#Crown|crown]] and progresses towards the [[Tooth - Anatomy & Physiology#Root|root]]. The tooth does not acquire full length until the crown has emerged. Tooth growth is appositional.
+*Premature loss of deciduous tooth leads to disorganised (non-occluding) permanent teeth
+==Test yourself with the Teeth and Gingiva Flashcards==
-{{Learning
+[[Oral Cavity - Anatomy & Physiology - Flashcards#Teeth & Gingiva Flashcards|Teeth & Gingiva Flashcards]]
-|flashcards= [[Teeth and Gingiva Flashcards]]
-|powerpoints= [[Oral Cavity Histology resource|Histology of the oral cavity, see part 2 for developing teeth]]
-}}
-{{OpenPages}}
 [[Category:Teeth - Anatomy & Physiology]]