Dentine sheet part 1

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Where can peritubular or intratubular dentine be found?

At the walls of newly formed dentinal tubules at the pulp surface

What is the primary location of intratubular dentine?

Pulp surface

Where is peritubular dentine predominantly present?

At the pulp surface

Which type of dentine is situated specifically at the walls of newly formed dentinal tubules?

Mantle dentine Signup and view all the answers

In which area do we find newly formed dentinal tubules?

Pulp chamber Signup and view all the answers

Why are dentin crystals much smaller than enamel hydroxyapatite?

Dentin crystals don't stack with each other. Signup and view all the answers

What distinguishes the size of dentin crystals from enamel hydroxyapatite?

Dentin crystals lack rod formation. Signup and view all the answers

How does the arrangement of dentin crystals differ from enamel hydroxyapatite?

Dentin crystals do not stack together like enamel hydroxyapatite. Signup and view all the answers

What property of enamel hydroxyapatite contributes to its larger size compared to dentin crystals?

Enamel hydroxyapatite forms rods. Signup and view all the answers

In what way do dentin crystals differ structurally from enamel hydroxyapatite?

Dentin crystals do not align in a stacked manner. Signup and view all the answers

What is the diameter of the tubules at the pulpal end?

2.5um Signup and view all the answers

What happens to the odontoblasts as they retreat inwards?

They occupy a smaller area Signup and view all the answers

What is the diameter of the tubules at the DEJ?

1um Signup and view all the answers

What happens to the tubules as the odontoblasts retreat inwards?

They become closer together Signup and view all the answers

What is the main factor affecting the distance between the tubules?

The retreat of the odontoblasts Signup and view all the answers

What shape do the tubules form?

A curved S shape Signup and view all the answers

What is the term for the curved S shape of the tubules?

Primary curvature Signup and view all the answers

What is the role of the primary curvature?

It forms a curved S shape Signup and view all the answers

What is the term used to describe the curvature of the tubules?

Primary curvature Signup and view all the answers

What is the primary curvature a characteristic of?

The curved S shape of the tubules Signup and view all the answers

What type of proteins are found in dentine?

Glycoproteins/sialoproteins Signup and view all the answers

Which of the following proteins is NOT found in dentine?

Osteocalcin Signup and view all the answers

What is the function of the acidic proteins found in dentine?

Cell signaling Signup and view all the answers

Which of the following is a characteristic of dentine sialoprotein?

It is an acidic protein Signup and view all the answers

Which of the following proteins is also found in bones?

Osteonectin Signup and view all the answers

Which glycosaminoglycan is listed as one of the main ones?

Chondroitin 4-sulphate Signup and view all the answers

What are the primary glycosaminoglycans found in dentine?

Chondroitin 4-sulphate and chondroitin 6-sulphate Signup and view all the answers

Which glycosaminoglycan mentioned is NOT one of the primary ones in dentine?

Chondroitin 6-sulphate Signup and view all the answers

What is a common glycosaminoglycan found in dentine that is NOT listed in the text?

Heparan sulfate Signup and view all the answers

Of the following options, which glycosaminoglycan is specifically mentioned as an 'imp'?

Dermatan sulfate Signup and view all the answers

What is the mineralization percentage of type I collagen in dentin compared to inter-tubular dentine?

5-12% Signup and view all the answers

Which type of collagen is primarily found in dentin?

Type III collagen Signup and view all the answers

What is the primary reason for dentin being more mineralized than inter-tubular dentine?

Less organic matrix Signup and view all the answers

In what way does the mineralization level of dentin impact its structural properties?

Improves resilience Signup and view all the answers

What is the main role of Phosphophoryn in dentine?

To facilitate mineralization Signup and view all the answers

Which of the following is a characteristic of Phosphophoryn?

It is the most acidic protein known Signup and view all the answers

What distinguishes Phosphophoryn from other proteins in dentine?

Its acidity Signup and view all the answers

How does Phosphophoryn contribute to the properties of dentine?

By promoting mineralization Signup and view all the answers

What makes Phosphophoryn significant in the study of dentine?

Its involvement in dentine formation Signup and view all the answers

Where are odontoblastic processes most heavily concentrated in the dentine?

Near the dentinoenamel junction Signup and view all the answers

What is the primary location of intratubular dentine?

Near the mineralising front Signup and view all the answers

What is a distinctive feature of dentin crystals compared to enamel hydroxyapatite?

Hexagonal shape Signup and view all the answers

Which type of proteins are primarily found in dentine?

Keratohyalin Signup and view all the answers

What property contributes to the larger size of enamel hydroxyapatite compared to dentin crystals?

Higher mineral content Signup and view all the answers

Which of the following is NOT a member of the SIBLING family?

Collagen Signup and view all the answers

What is the primary function of the acidic proteins found in dentine?

Regulating mineralization Signup and view all the answers

Which of the following glycosaminoglycans is listed as one of the main ones in dentine?

Chondroitin sulfate Signup and view all the answers

Which of the following proteins is also found in bones?

Osteopontin Signup and view all the answers

Which of the following is a characteristic of dentine sialoprotein?

Binding to integrins Signup and view all the answers

What is the primary difference between crystals in enamel and those in dentine?

Size Signup and view all the answers

Which component makes up approximately 20% of the organic composition in dentine?

Phosphophoryn Signup and view all the answers

Where is peritubular dentine predominantly located?

Around the tubules Signup and view all the answers

What is the distinctive feature of dentin crystals compared to enamel hydroxyapatite?

Size Signup and view all the answers

What type of proteins are primarily present in dentine?

Acidic proteins Signup and view all the answers

What is the refractive index of water in relation to dentine in the described process?

Not specified in the given text Signup and view all the answers

Which protein, mentioned in the text, is NOT also found in bones?

Phosphophoryn Signup and view all the answers

Which glycosaminoglycan is mentioned as an 'imp' in dentine?

Heparan sulphate Signup and view all the answers

What is the percentage of mineralization of type I collagen in dentin compared to inter-tubular dentine?

Not specified in the given text Signup and view all the answers

What happens to the regions with patent tubules when a ground section of a root is placed in water?

They fill with water and appear opaque Signup and view all the answers

Which protein is primarily found in intratubular dentine and differs from phosphophoryn?

Dentin phosphoprotein Signup and view all the answers

Which characteristic of dentine sialoprotein contributes to the unique structural properties of dentine?

Its ability to bind calcium Signup and view all the answers

Which glycosaminoglycan is mentioned as an 'imp' in dentine and what is its role?

Dermatan sulfate, regulating collagen fibril assembly Signup and view all the answers

Which protein found in dentine also plays a role in bone mineralization?

Collagen type I Signup and view all the answers

Which characteristic of enamel hydroxyapatite contributes to its larger size compared to dentin crystals?

Its lower organic content Signup and view all the answers

Which of the following mechanisms is likely responsible for the presence of more peritubular dentine at the DEJ?

An increased rate of formation of peritubular dentine due to higher mineralization Signup and view all the answers

Which protein is most likely responsible for the smaller size of odontoblastic processes at the DEJ?

Phosphophoryn Signup and view all the answers

Which of the following mechanisms could explain the smaller diameter of tubules at the DEJ?

An increased deposition of peritubular dentine around the odontoblastic processes Signup and view all the answers

What is the significance of the smaller odontoblastic processes at the DEJ for the overall properties of dentine?

It enhances the overall strength of dentine in the DEJ region Signup and view all the answers

Which glycosaminoglycan is NOT likely to be involved in the regulation of mineralization at the DEJ, given the properties of this region?

Fibromodulin Signup and view all the answers

What is the specific role of phospholipids in the formation and growth of dentine crystals?

They act as a template for crystal nucleation. Signup and view all the answers

How do the structural differences between dentin crystals and enamel hydroxyapatite impact their properties?

Dentin crystals are smaller and less ordered, making them more susceptible to acid dissolution. Signup and view all the answers

What is the significance of Phosphophoryn in dentine mineralization and its structural properties?

Phosphophoryn promotes the formation of dentin crystals, contributing to dentine stiffness. Signup and view all the answers

How do the glycosaminoglycans found in dentine impact its structural and functional properties?

They provide flexibility and resilience to dentine. Signup and view all the answers

What is the impact of the primary curvature of the tubules on the structural properties of dentine?

The curvature enhances dentine's ability to distribute stress evenly. Signup and view all the answers

Study Notes

Peritubular Dentine

Found at the walls of newly formed dentinal tubules at the pulp surface
Smaller than enamel hydroxyapatite, do not stack with each other, and do not form rods
Dentine tubules are 2.5 um in diameter at the pulpal end, decreasing to 1um or less at DEJ as odontoblasts retreat inwards

Dentine Structure

Dentine tubules have a curved S shape, known as primary curvature, and are not straight
As odontoblasts retreat inwards, tubules become closer due to the smaller area occupied

Dentine Composition

Contains acidic proteins, including osteonectin, osteopontin, and dentine sialoprotein
Main glycosaminoglycans are chondroitin 4-sulphate and chondroitin 6-sulphate
Made of highly mineralized type I collagen (5-12% more mineralized than inter-tubular dentine)

Non-Collagenous Proteins

Phosphophoryn (PP-H): the main phosphoprotein in dentine, implicated in mineralization, and the most acidic protein known
Phosphophoryn is most heavily concentrated near the mineralizing front in predentine
SIBLING (small integrin-binding ligand N-linked glycoproteins) family includes osteopontin, bone sialoprotein, DMP-1, matrix extracellular phosphoglycoprotein, and dentine sialophosphoprotein

Inorganic Material

Found on and between collagen fibrils

Dentine Crystals

Different from enamel crystals

Organic Composition

Accounts for 20% of dentine composition
Includes basic information about phospholipids, which are needlelike 'crystal ghosts' and may be involved in the formation and growth of crystals

Translucent Dentine

Regions blocked by peritubular dentine appear translucent when a ground section of a root is placed in water
Regions with patent tubules appear opaque when filled with water

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