Week 13: Introduction to Endodontics

Question 1

What are the main cells of the pulp?

Answer 1

Odontoblasts
Fibroblasts

Question 2

What are the roles of odontoblasts?

Answer 2

Odontoblasts
* Responsible for the secretion of dentin and the formation of dentinal tubules in the crown and root
* Lifespan s the same as the vital tooth. Once formed this cell cannot undergo mitotic divsion

Question 3

What are the roles of Fibroblasts?

Answer 3

Fibroblasts
* Fibroblasts are the most prevalent cells in the pulp tissue. Their function is to form and maintain the pulp extracellular matrix. It consits of collagens and non-collagenous proteins
* Collagen types type I and III comprise the huge majority of the total collagen in the pulp tissue
* Higher density can be found around blod vessels and nerves

Question 4

Answer the following:
1. Define pulp Cavity
2. Classify dental pulp (hard tissue, soft tissue etc.)
3. What is the cellular composition of dental pulp?

Answer 4

1. Pulp cavity: **pulp chamber and root canal **
2. The dental pulp is classified as soft connective tissue
3. It is compsed of cells: odontoblasts, fibroblasts, and other cells

Question 5

Describe other components that make up the pulp (neruovasculature etc.)

Answer 5

Vessels
* The pulp is a richly vascularized organ. Arterioles enter, and venules and lymphatic vessels leave the dental pulp through the apical foramina, apical ramifications and lateral canals

Nerves
* Pulp nerves usually follow the blood vessels as they extend coronally and branch. Two types: Fibers A and C

**Intracellular Ground Substance **
* It is transparent colourless, and fills the spaces between fibers and cells. It is rich in proteoglycans, glycoproteins and large amounts of water.

Question 6

Discuss other cells of the Pulp

Answer 6

**The dental pulp is a richly vascularized organ

• Other cells of the pulp are present specifically during inflammatory responses, observed along small vessels
• In close proximity to endothelial cells, mesenchymal cells, named pericytes, are observed
• Also, macrophages (also known as histocytes) are observed as sentinels along with dendritic cells, associated with immunosurveillance and antigen presentation

Question 7

In a histological slide of normal dental pulp what are the layers (from inner to outside)?

Answer 7

1. Cell Rich Zone (?)
2. Cell Free Zone (Weil’s Zone)
3. Odontoblast Layer
4. Predentin
5. Dentin

Question 8

Describe pulpal innervation (include fiber types, approximate compositions and fiber characteristics)

Answer 8

Sensory Innervation
* Three types of Trigeminal Sensory Nerve Fibers: A-Beta, A-Delta, and C Fibers
* A-Beta (5%) and A-Delta (15%) are myelinated with very fast conduction speed and a low excitablity threshold. They mediate the sharp, transient pain typical of dentin sensitivity
* C-Fibers are unmyelinated, with slow conduction speed and high excitability threshold. Produces pain that is dull, aching, excrutiating, and sometimes diffuse, typical of symptomatic irreversible pulpitis.

Question 9

What is Rashkow’s Nervous Plexus?

Answer 9

Rashkow’s Nervous Plexus
* At the subodontoblastic Cell-Free Zone, nerve fibers give rise to a rich network of terminal endings to form the Rashkow’s Nervous Plexus
* After leaving the Rashkow’s Nervous Plexus, fibers lose their wrapping and terminate as free nerve endings at the odontoblast layer and pulpal border of dentin

Question 10

Describe the dentin-pulp complex, how vital pulp can be affected when compromised, and the pathways of root infection.

Answer 10

Pathways of root infection
* The dentin-pulp complex is normally sterile and isolated from the oral microbiota by overlying enamel and cementum
* If these protective layers are lost, the dentin-pulp complex is exposed to oral bacteria and put at risk of infection
* Once exposed, dentin may represent a route for bacteria to reach the pulp via tubules. However, as long as the pulp is vital, dentinal exposure does not represent a significant route of pulp infection, except when dentin thickness is considerably reduced, and dentin permeability is significantly increased
* In situations where the vitality of the pulp is compromised and defense mechanisms are impaired, even very few bacteria may intiate infection
* Exposed pulps will undergo inflammation, necrosis, and become infected
* Restorative procedures
* Pulp penetration by caries
* Trauma cases (?)

Question 11

What are four types of pulp diseases?

Answer 11

• Reversible pulpitis
• Symptomatic irreversible pulpitis
• Asymtomatic irreversible pulpitis
• Pulp necrosis

Question 12

Describe normal pulp in health

Answer 12

Normal pulp
* Teeth with normal pulp do not usually exhibit any spontaneous symptoms. The pulp is symptom-fre and normally responsive to pulp testing. Symptoms are mild, do not cause the patient distress, and result in a transient sensation that resolves in seconds.
* Radiographically, there may be varying degress of pulpal calcification but no evidence of resorption, caries, or mechanical pulp exposure

Question 13

Describe Reversible Pulpitis

Answer 13

Reversible Pulpitis
* This clinical diagnosis is based on subjective and objective findings indicating that inflammation should resolve and the pulp return to normal
* When the pulp stimulation is uncomfortable t the patient but reverses quickly after irritation, it is classified as reversible pulpitis
* Conservatibe removal of the irritant will resolve the symptoms

Question 14

What is Dentin Sensitivity?

Answer 14

Dentin Sensitivty
* Confusion can occur when there is exposed dentin, without evidence of pulp pathosis, which can sometimes respond with sharp, quickly reversible pain when subjected to thermal, evaporative, tactile, mechanical, osmotic, or chemical stimuli. This is known as dentin sensitvity or hypersensitivity.

Question 15

What is Irreversible Pulpitis?

Answer 15

Irreversible Pulpitis
* As the disease state of the pulp progresses, the inflammatory condition of the pulp can change to irreversible pulpitis. At this stage, treatment to remove the diseased pulp will be necessary.
* This condition can be divided into subcategories of symptomatic and asymptomatic irreversible pulpitis

Question 16

Describe symptomatic irreversible pulpitis

Answer 16

Symptomatic Irreversible Pulpitis
* Symptomatic irreversible pulpitis exhibits intermittent or spontaneous pain
* Rapid exposure to dramatic temperature changes (especially to cold stimulit) will elicit prolonged pain episodes even after the thermal stimulus has been removed.
* The pain in these cases may be sharp or dull, localized, diffuse, or referred
* There are minimal or no changes in the radiographic appearance of the periradicular bone. With advanced irreversible pulpitis, a thickening of the periodontal ligament may become apparent on the radiograph

Question 17

Describe Asymptomatic Irreversible Pulpitis

Answer 17

Asymptomatic Irreversible Pulpitis
* This is a clinical diagnosis based on subjective and objective findings indicating that the vital inflamed pulp is incapable of healing.
* The patient does not complain of any symptoms
* Deep caries will not produce ant symptoms even though, clinically or radiographically, caries may extend well into the pulp

Question 18

What is pulp necrosis?

Answer 18

Pulp necrosis
* This is a clinical diagnostic category indicating death of the dental pulp. The pulp is usually nonresponsive to pulp testing
* The pulpal blood supply is nonexistent and the pulpal nerves are nonfunctional. It is the only clinical classification that directly attempts to describe the histologic status of the pulp
* This condition is subsequent to symptomatic or asymptomatic irreversible pulpitis
* Tooth is asymptomatic until such time when there is an extension of the disease process into the periradciular tissues
* The tooth will usually not respond to electric pulp tests or to cold stimulation
* If heat is applied for an extended period of time, the tooth may respond to this stimulus. The tooth is often relieved by applications of cold
* Pulpal necrosis may be partial or complete, and it may not involve all of the ca als in a multirooted tooth
* Radiographic changes may occur, ranging from a thickening of the periodontal ligament space to the apperance of a periapical radiolucent lesion

Question 19

What are 4 types of apical disease?

Answer 19

• Symptomatic apical periodontitis
• Asymptomatic apical periodontitis
• Acute apical abscess
• Chronic apical abscess

Question 20

Describe Symptomatic apical periodontitis

Answer 20

Symptomatic apical periodontitis

• This condition is defined as an inflammation of the apical periodontium, producing clinical symptoms, including a painful response to biting or percussion or palpation
• The radiograph or image of the tooth will typically exhibit at least a widend periodontal ligament space and may or may not show an apical radiolucency associated with one or all of the roots.

Question 21

Describe asymptomatic apical periodontitis

Answer 21

Asymptmatic apical periodontitis

• This condition is defined as inflammation and destruction of the apical periodontum that is of pulpal origin; it appears as an apical radiolucent area and does not produce clinical symptoms
• The radiograph or image of the tooth will exhibit an apical radiolucency
• The tooth is generally not sensitive to biting pressure but may “feel different” to the patient on percussion

Question 22

What is an acute apical abscess?

Answer 22

Acute apical abscess

• This condition is defined as an inflammatory reaction to pulpal infection and necrosis characterized bu rapid onset, spontaneous pain, tenderness of the tooth to pressure, pus formation, and swelling of associated tissues.
• A tooth with an acute apical abscess will be acutely painful to biting pressure, percussion, and palpation, varying degress of mobility
• Swelling will be present intraorally and the facial tissues adjacent to the tooth will almost always present with some degress of swelling
• The radiograph or image can exhibit anything from a widened periodontal ligament space to an apical radiolucency
• The patient will frequently be febrile, and the cervical and submandibular lymph nodes may exhibit tenderness to palpation.

Question 23

What is a chronic apical abscess?

Answer 23

Chronic apical abscess
* This condition is defined as an inflammatory reaction to pulpal infection and necrosis characterized by gradual onset, little or no discomfort, and the intermittent discharge of pus through an associated sinus tract
* The radiograph or image will exhibi an apical radiolucency. The tooth is not sensitive to biting pressure but can “feel different” to the patient on percussion
* This entity is distinguished from asymptomatic apical periodontitis because it will exhibit intermittent drainage through an associated sinus tract

Question 24

Question 25

Answer 25

Irrevserible sympt pulpitis

Question 26

Answer 26

Reversible pulpitis

Question 27

Answer 27

Chronic Apical perio