Biological Considerations of Tooth Structures

What are some adaptive immune system pulp reactions?

1) Antigen-specific immune response 2) Lymphocytes (B cells and T cells) 3) Cytokines, chemokine and antibodies

What are some innate immune system pulp reactions?

1) Interstitial fluid 2) Odontoblasts 3) Neurogenic Inflammation 4) Innate immune system cells (macrophages, neutrophils, dendritic cells e natural-killer) 5) Cytokines and chemokines

What is the percent composition of dentin?

50% inorganic material (mineral) 30% organic matrix/proteins 20% water

What is the percent composition of enamel?

90% mineral 9% Water 1% Organic

What does tome's process consist of?

A proximal and distal portion

What happens generally during the maturation stage of amelogenesis

Ameloblasts degrade enamel matrix and then mineralizing it again to create more enamel

How does amelogenesis produce enamel generally?

Ameloblasts produce enamel matrix proteins that become mineralized

What happens during the transitional phase of the maturation stage of amelogenesis?

Ameloblasts reduce in height + volume 25% go through apoptosis

What happens generally during the secratory stage of amelogenesis

Ameloblasts secrete organic matrix forming full enamel thickness

Describe the mineralization of dentin

As the odontoblasts are decending and making more dentin, the initial secretion is unmineralized. This is predentin. (always present) predentin is then mineralized along the mineralization front, into circumpulpal dentin.

What happens during the maturation proper phase of the maturation stage of amelogenesis?

Bulk of the water in the organic matrix is replaced with inorganic material to mineralize the enamel done through modulation

How does crystallization of the circumpulpal dentin work?

Calcium is transported from sub-odontoblastic layer to the mineralization front to mineralize

What is the initial secretion of the odontoblasts?

Collagen + Non-collagenous proteins

What is modulation?

Cyclic creation, loss and re-creation of a ruffle-ended apical/distal surface in an ameloblast

What is the organization of dental pulp?

Dentin Predentin Odontoblast Zone Cell-free zone Cell-rich zone Pulp core

How does odontogenesis begin?

During the early bud stage, inner epithelium cells trigger dental papilla cells to differentiate into pre-odontoblasts and eventually into an odontoblast

What is the final enamel and what is positionally important about it?

Final enamel is enamel with rods and inter-rods sandwiched by enamel with out rods

What is enamel?

Hardest substance in the body, covers the crown of the tooth.

What are the two layers of dentin that will be formed?

Mantle Dentin Circumpulpal Denting

What are the two steps of the presecretory stage?

Morphogenetic phase Differentiation phase

What happens so odontoblasts after the creation of the mantle dentin?

Odontoblastic process (Tome's fiber) that extends in to the extra cellular matrix

How does crystallization of the mantle dentin work?

Odontoblasts leave behind matrix vesicles that release proteins that bind calcium + phosphate

What are the two types of final-form dentin

Peritubular dentin interlobular dentin

What are the three stages of amelogenesis?

Pre-secretory Secretory Maturation

What is the difference between primary, secondary and tertiary dentin?

Primary dentin is secreted until eruption at a fast rate Secondary dentin is secreted throughout life at a slow rate mild environmental stimuli can stimulate tertiary dentin to be secreted (pathological)

What does the difference in secretion of the proximal and distal tome's process create?

Proximal secretion - inter-rod enamel Distal secretion - enamel rods

Once the odontoblast is created, what happens?

Rouch ER, ribosomes, Golgi complexes, and mitochondria are produced Nucleus becomes polarized away from the inner enamel epithelium

How do ruffle-ended and smooth-ended ameloblasts work together?

Ruffle ended ameloblasts release lysosomes, metalloproteinases, serine proteinases into the enamel matrix to break it down these broken down pieces diffuse into the smooth ended ameloblasts (ruffled ones also use endocytosis to take broken down pieces) ruffle-ended ameloblasts then release calcium binding proteins and calcium ATPase to bring calcium ions into the region to mineralize the enamel matrix

What does the tome's process do?

Site of secretion of enamel (initial layer is mantle layer)

How does superficial and deep dentin differ?

Superficial - more mineralized areas - smaller tubules

As the more and more enamel is produced, what happens to tome's process?

The distal portion of tome's process continues to penetrate the enamel, creating rod + inter-rod enamel

As more dentin is deposited, what happens to the odontoblastic process (tome's fiber)?

They keep lengthening in the fully formed dentin, leaving behind dentinal tubules (not in the mantle dentin)

Once the initial layers of dentin are formed, what do ameloblasts do?

They will begin the secretory stage (make note of reciprocal induction happening here)

What is positive interstitial fluid pressure and why is it helpful?

This means that it is constant pushing from within so pathogens will have a harder time entering

What structure develops during the secretory stage of amelogenesis?

Tome's Process

What are the two steps of the maturation stage of amelogenesis?

Transistional phase Maturation Proper phase

What type of collage comprises the mantle dentin?

Type I Collagen Korff's Fibres (Type III)

What is circupulpal dentin matrix comprised of?

Type I Collagen Non-Collagenous proteins Proteoglycans

What happens during the morphogenetic phase of the presecretory stage of amelogenesis?

bell stage is established cuboidal inner enamel epithelium cells have nuclei in the center and Golgi complexes on the proximal portion of the cell (towards the stratum intermedium)

Contrast carious dentin from regular dentin

carious is soft, wet, readily excavated, light yellow to orange

the space left in-between the rod and inter-rod enamel when the tome's process is squeezed out gets filled by what and is called what?

filled with organic material and called the enamel sheath

What happens during the differentiation phase of the presecretory stage of amelogenesis?

inner epithelium cell elongates and become columnar nuclei become proximal (towards stratum intermedium) Golgi complex shifts distally (towards dental papilla) Mitochondria shift proximally

What happens generally during the pre-secratory stage of amelogenesis

inner epithelium cells differentiate to form ameloblasts, ready for secretion

What is happening at the same time as the differentiation of inner epithelial cells into ameloblasts?

signaling molecules from the inner epithelial cells trigger the dental papillary cells to differentiate into odontoblasts and make dentin