CHAPTER 1 - HIGH YIELD

What is the dental pulp histologically?

Loose connective tissue in the center of the tooth

What is the water and organic material percentage composition of the dental pulp?

75% water and 25% organic material

What is the primary function of the dental pulp?

Dentin formation and repair

What is the inductive function of dental pulp?

dentine formation which induces enamel formation

What pulp function coordinates inflammatory, antigenic, neurogenic, and dentinogenic responses?

Defensive

What type of sensation does the pulp transmit?

Pain (nociception)

Which pulp layer is in the center and contains mostly fibroblasts, nerves, and blood vessels?

Pulp core

What pulp layer lies internal to the cell-free zone?

Cell rich zone

What is another name for the cell-poor zone of the pulp?

Zone of Weil

What structures are contained within the cell-poor zone (zone of Weil)?

Capillaries and nerve plexus of Raschkow

When might the cell-poor zone not be apparent?

In young pulps (rapid dentin formation) or older pulps (reparative dentin production)

What is the outermost pulp layer containing odontoblasts lying next to predentin?

Odontoblastic layer

What are the principal and most numerous cells of the pulp?

Fibroblasts

What types of collagen are synthesized by pulpal fibroblasts?

Types I and III collagen

What cellular function allows fibroblasts to maintain matrix proteins and handle collagen turnover?

Phagocytose and digest collagen

Which pulpal cells are most capable of transforming into other cells after destruction?

Undifferentiated mesenchymal cells (Stem cells)

What are the key signaling molecules responsible for mesenchymal stem cell transformation?

Bone morphogenetic protein (BMP) family and transforming growth factor beta (TGF-beta)

Where are odontoblast cell bodies located?

Pulp cavity

What are the cytoplasmic processes of odontoblasts called?

Tomes fibers

What structures can Tomes fibers cross to form enamel spindles?

Dentinoenamel junction (DEJ)

What structure does each dentinal tubule contain along with a layer of peritubular dentin?

Tomes fibers

What type of dentin surrounds each dentinal tubule?

Peritubular dentin

Is peritubular dentin more or less mineralized than surrounding intertubular dentin?

More mineralized

Where are dentinal tubules smaller and more sparsely distributed?

Superficial dentin near DEJ (and in root dentin)

Where are dentinal tubules larger and more numerous?

Deep dentin

How do root dentinal tubules compare with coronal tubules?

Smaller and less numerous

How are adjacent odontoblast cell bodies connected?

Desmosomes (zonula adherens), tight and gap junctional complexes

What protein forms gap junctions between odontoblasts to permit cell-to-cell passage of signal molecules?

Connexin proteins

What type of collagen does the odontoblast synthesize mainly?

Type I collagen

What enzymes are secreted by odontoblasts?

Acid phosphatase and alkaline phosphatase

What is the most prominent immune cell in the dental pulp?

Dendritic cell

What is the main function of dendritic cells?

Antigen presentation

Where are dendritic cells most densely located in the dental pulp?

Odontoblast layer and around blood vessels

What are dendritic cells in the epidermis and mucous membranes called?

Langerhans cells

What are resting form macrophages in the pulp called?

Histiocytes

Which lymphocytes are present in normal uninflamed pulp?

T cells

Which lymphocytes are scarcely found in normal uninflamed pulp?

B lymphocytes and plasma cells

Which immune cells are seldom found in normal pulp but routine in chronic inflammation?

Mast cells

Which immune cells are found only in diseased pulp?

Neutrophils

When are mast cells routinely found in pulp?

Chronic inflammation

Which cells are scarce in normal uninflamed pulp?

Plasma cells

Which cells characterize chronic pulp inflammation?

Lymphocytes

Macrophages

Plasma cells

What collagen types are found in pulp?

Type I and III

What is the ratio of Type I to Type III collagens found within the pulp?

Approximately 55:45

Which pulpal cells produce Type I collagen for incorporation into dentin?

Odontoblasts

Which pulpal cells produce both Type I and Type III collagen?

Fibroblasts

Which collagen type is predominant in dentin?

Type I collagen

Which portion of the pulp has more collagen to facilitate pulpectomy?

Apical portion

How does collagen content and organization change with age in the pulp?

Increase in overall collagen content and increase in organization into bundles

Are there elastic fibers in the pulp matrix?

No evidence for elastic fibers

What histologically clear gel makes up the non-collagenous matrix of the pulp?

Glycosaminoglycans and other adhesion molecules

Where is Type I collagen found?

Skin, tendon, bone, dentin, and pulp

Where is Type II collagen found?

Cartilage

Where is Type III collagen found?

Most unmineralized connective tissues (fetal form in dental papilla and mature pulp)

Where are Types IV and VII collagen found?

Components of basement membranes

Where is Type V collagen found?

Constituent of interstitial tissues

Where is Type VI collagen found?

Widely distributed in low concentrations in soft tissues at interfibrillar filaments

Which cells synthesize type I collagen in the pulp and bone?

Odontoblasts and osteoblasts

Which collagen types are synthesized by fibroblasts?

I, III, V, and VII collagen

Where do pulp stones occur?

Normal pulps and chronically inflamed pulps (in both young and old patients)

Are pulp stones responsible for painful symptoms?

No

What is diffuse pulpal calcification also called?

Pulpal sclerosis

Where do diffuse (pulpal sclerosis) or linear calcifications occur in the pulp?

Associated with neurovascular bundles in the pulp core

In which type of pulp are diffuse or linear calcifications seen most often?

Aged, chronically inflamed, or traumatized pulp

What are free pulp stones?

Stones surrounded by pulp tissue

What are attached pulp stones?

Stones continuous with the dentin

What are embedded pulp stones?

Stones surrounded entirely by tertiary dentin

What is calcific metamorphosis?

Pulpal response to trauma characterized by rapid hard tissue deposition in root canal space

What clinical crown sign is associated with calcific metamorphosis?

Yellowish discoloration of the crown

What happens to the pain threshold to thermal and electrical stimuli during calcific metamorphosis?

Usually increases

When does primary dentin form?

During tooth development (until eruption)

What outlines the pulp chamber and possesses a regular tubular structure?

Primary dentin

What is mantle dentin?

The outer layer of primary dentin that is less mineralized and formed by early odontoblasts

When does secondary dentin form?

After root formation is complete

How does the mineral/organic ratio of secondary dentin compare to primary dentin?

Same ratio

How is secondary dentin deposition characterized?

Slower deposition, tubular but less regular, and uneven deposition

Where does secondary dentin deposit more heavily to cause pulp recession?

Roof and floor of the pulp chamber

When does tertiary dentin form?

In response to stimuli like caries and trauma

What is the architecture of tertiary dentin dependent on?

Intensity and duration of stimulus

What is reactionary tertiary dentin?

Tertiary dentin formed by existing odontoblasts

What is reparative tertiary dentin?

Tertiary dentin formed by new odontoblast-like cells

What causes sclerotic dentin?

Gradual aging or response to mild injury

What characterizes sclerotic dentin?

Dentinal tubules occluded by calcification making it glassy, translucent, and less permeable

Where is sclerotic dentin found?

Helps protect pulp, seen with age especially in apical root and mid-crown

What is predentin?

A layer of unmineralized matrix lining the innermost pulpal portion

What does predentin consist of mainly?

Collagen fibers (similar structure to osteoid)

When is predentin thickest?

At times when active dentinogenesis is occurring

What happens to predentin thickness with age?

Reduces in thickness with age

What happens to pulp size with secondary and tertiary dentin formation?

Decreases

Which divisions of the trigeminal nerve provide sensory innervation to maxillary and mandibular pulps?

Second and third divisions (V2 and V3)

Does the dental pulp receive parasympathetic innervation?

No parasympathetic innervation

What system provides motor innervation to the dental pulp?

Sympathetic innervation from T1 (and to some extent C8 and T2)

What is the function of sympathetic innervation in the pulp?

Maintain vasomotor tone in precapillary sphincters controlling blood pressure and distribution

What type of fibers are A-delta fibers?

Large myelinated fibers

What are large, myelinated A-delta fibers responsible for?

Quick, sharp, momentary pain (dentin pain) that dissipates quickly on stimulus removal

Where do A-delta and C fibers fibers enter the pulp?

Apical foramen

Where do A-delta fibers branch?

Plexus of Raschkow

Where do A-delta fibers terminate?

Below odontoblasts, around odontoblasts, or alongside odontoblast process in the dentinal tubule

What happens to A-delta myelin before termination?

It is lost

How quickly is A-delta pain perceived How long does A-delta pain usually last after stimulus removal?

Immediately

Briefly