Lect. 5 4

Lect. 5 4th stage
Definition and objective of endodontic treatment
Endodontics: is the specialty of dentistry that manages the prevention, diagnosis, and treatment of the dental pulp and the
periradicular tissues that surround the root of the tooth.
History of root canal preparation:
1. Edward Maynard has been credited with the development of the first endodontic hand instruments. Notching a round
wire (in the beginning watch springs, later piano wires) he created small needles for extirpation of pulp tissue. In 1852
Arthur used small files for root canal enlargement.
2. In 1852 Arthur used small files for root canal enlargement.
3. Dentists in the middle of the 19th century recommended that root canals should be enlarged with broaches, this
instrument is employed to enlarge the canal, and give it a regular shape.
4. In 1885 the Gates Glidden drill.
5. In 1915 the K-file were introduced.
6. In 1929 by Trebitsch standardization of instruments had been proposed.
7. Ingle in 1958, ISO specifications for endodontic instruments were not published before 1974.
Dentin_pulp complex:
Dentin and pulp are embryological, histologically, and functionally the same tissue and therefore are considered as a complex.
Types of Dentin
1. Primary dentin: is the dentin formed in a tooth before the completion of the apical foramen of the root. Primary
dentin is noted for its regular pattern of tubules.
2. Secondary dentin: is the dentin that is formed after the completion of the apical foramen and continues to form
throughout the life of the tooth.
3. Peritubular (intratubular) dentin: dentin that creates the wall of the dentinal tubule.
4. Intertubular dentin: dentin found between the tubules.
5. Mantle dentin: the first predentin that forms and matures within the tooth.
6. Circumpulpal dentin: the layer of dentin around the outer pulpal wall.
7. Dentine is permeable, Permeability increases, the less the remaining dentine thickness.
Functions of the Dental Pulp:
Nutrition: blood supply for pulp and dentin.
Sensory: changes in temp., vibration and chemical that affect the dentin and pulp.
Formative: the pulp involve in the support, maintenance and continued formation of dentin.
Defensive: triggering of inflammatory and immune response.
Protective: Development and formation of secondary and tertiary dentin which increase the coverage of the pulp.
Contents of the Pulp:
1. Cells: Odontoblast, Fibroblast, white-blood cells, Undifferentiated mesenchymal cells, Macrophages and Lymphocytes.
No fat cell.
2. Fibrous Matrix: Mostly reticular fibres and collagen fibres (Type I and Type III).
3. Ground substance: Act as a medium to transport nutrients to cells and metabolites of the cell to the blood vessels.
Vascularity and Nerves of the Pulp:
1. The pulp organ is extensively vascular with vessels arising from the external carotids to the superior or inferior alveolar
arteries. It drain by the same vein.
2. Blood flow is more rapid in the pulp than in most area of the body, and the blood pressure is quite high.
3. The walls of the pulpal vessels become very thin as their enter the pulp.
4. Nerves : Several large nerves enter the apical canal of each Molar and Premolar and single ones enter the anterior
teeth. This trunks transverse the radicular pulp, proceed to the coronal area and branch peripherally.
Nerves and vessels in pulp:
Blood and vessels enter and exit the dental pulp by way of the apical and accessory foramina. Pulp is richly innervated; nerves
enter the pulp through the apical foramen, along with afferent blood vessels and together form the neuro-vascular bundle.
Dentin Sensitivity: three theories:
1. Nerve in dentin – the dentin contains nerve endings that respond when it is stimulated .
2. Odontoblastic process – the odontoblasts serve as receptors and are coupled to nerves in the pulp.
3. Fluid movements in the dentinal tubules – the tubular nature of dentin permits fluid movement to occur within
the tubule when a stimulus is applied a movement registered by pulpal free nerve endings close to the dentin.
Signs and Symptoms of Pulpal Nerve Damage:
Pain when biting down.
Pain when chewing.
Sensitivity with hot or cold beverages.
Facial swelling.
Subjective examination:
Chief complaint.
Character and duration of pain.
Painful stimuli.
Sensitivity to biting and pressure.
Objective examination:
Extent of decay.
Periodontal conditions surrounding the tooth in question.
Presence of an extensive restoration.
Tooth mobility.
Swelling or discoloration‫ز‬
Pulp exposure.
Radiographs in Endodontics:
1. Initial radiograph
a. Diagnosis.
2. Working length film
a. Used to determine the length of the canal.
3. Final instrumentation film
a. Taken with the final size files in all canals.
4. Root canal completion film
a. Taken after the tooth as been temporized.
5. Recall films
a. Taken at evaluations.
Requirements of Endodontic Films:
1. Show 4-5 mm beyond the apex of the tooth and the surrounding bone or pathologic condition.
2. Present an accurate image of the tooth without elongation or fore-shortening.
3. Exhibit good contrast so all pertinent structures are readily identifiable.
Diagnostic Conclusions:
1. Normal pulp
a. There are no subjective symptoms or objective signs. The tooth responds normally to sensory stimuli, and a
healthy layer of dentin surrounds the pulp.
2. Pulpitis
a. The pulp tissues have become inflamed.
3. Reversible pulpitis
a. The pulp is irritated, and the patient is experiencing pain to thermal stimuli.
4. Irreversible pulpitis
a. The tooth will display symptoms of lingering pain.
5. Periradicular abscess
a. An inflammatory reaction to pulpal infection that can be chronic or have rapid onset with pain, tenderness of
the tooth to pressure, pus formation, and swelling of the tissues.
6. Periodontal abscess
a. An inflammatory reaction frequently caused by bacteria entrapped in the periodontal sulcus. A patient will
experience rapid onset, pain, tenderness of the tooth to pressure, pus formation, and swelling.
7. Periradicular cyst
a. A cyst that develops at or near the root of a necrotic tooth. These types of cysts develop as an inflammatory
response to pulpal infection and necrosis of the pulp.
8. Pulp fibrosis
a. The decrease of living cells within the pulp causing fibrous tissue to take over the pulpal canal.
9. Necrotic tooth
a. Also referred to as nonvital. Used to describe a tooth that does not respond to sensory stimulus.
Endodontic treatment:
1. Pulp capping
a. A covering of calcium hydroxide is placed over an exposed or nearly exposed pulp to encourage the formation
of irritated dentin at the site of injury.
2. Indirect pulp cap is indicated when a thin partition of dentin is still intact.
3. Direct pulp cap is indicated when the pulp has been slightly exposed.
4. Pulpotomy
a. Involves the removal of the coronal portion of an exposed vital pulp.
b. Completed to preserve the vitality of the remaining portion of the pulp within the root of the tooth.
c. This procedure is commonly indicated for vital primary teeth, teeth with deep carious lesions, and emergency
5. Pulpectomy
a. Also referred to as root canal therapy; procedure involves the complete removal of the dental pulp.
Endodontic (Root Canal) Treatment, Step By Step
Preliminary treatment to remove the decay and the source of infection of the pulp is necessary, along with a
determination of whether the lost tooth structure can be restored. If a fracture of the tooth has reached the pulp, or infection
is associated with gum disease, it could be more difficult, if not impossible, to save the tooth.
The general sequence of a root canal procedure is as follows:
Step 1
Local anesthesia is administered via injections to numb the tooth to be treated and the surrounding tissues. If the
pulp in a tooth is acutely inflamed, and therefore very painful, it may take a while to get it numb, but your dentist will not start
the treatment until it is.
Step 2
A dental dam — a thin sheet of rubber or vinyl — will be placed over the affected and adjacent teeth. The tooth
undergoing treatment protrudes through a hole punched in the dam, isolating it from the rest of the mouth. This allows the
root canal treatment to be carried out in a sterile environment free from contamination by bacteria found in saliva or the rest
of the mouth.
Step 3
A small access hole is drilled through the biting surface of an affected back tooth or from behind a front tooth,
allowing access to the pulp chamber and root canals for treatment.
Step 4
The diseased and dead pulp tissue is removed from the tooth with specially designed instruments used to clean out
the root canals and pulp chamber. This is not painful; the area is numb and the tissue being removed is either dead or dying.
Once the pulp, along with the nerves contained in it, is removed, the tooth itself can no longer feel pain.
Step 5
The canals are disinfected with antiseptic and antibacterial solutions.
Step 6
The canals are then shaped with tiny flexible instruments to allow them to receive root canal fillings and sealers.
The canals are washed and cleaned again to remove root canal debris prior to sealing them.
Step 7
Root canal fillings are selected that will exactly fit into the freshly prepared canals. Usually a rubber-like material
called gutta-percha is used to fill the canal space. It is a thermoplastic material (“thermo” – heat; “plastic” – to shape), which
literally is heated and then compressed into and against the walls of the root canals to seal them. Together with adhesive
cement called a sealer, the gutta-percha fills the prepared canal space. Sealing the canals is critically important to prevent
them from becoming reinfected with bacteria.
Step 8
A temporary or permanent filling material will then be placed to seal the access hole that was made to treat the
canals, and the dental dam is removed. If the tooth lacks sufficient structure to hold a restoration (filling) in place, the dentist
or endodontist may place a post (either metal or a very strong plastic) in one of the canals inside the tooth to help retain it.
Step 9
After the procedure, an antibiotic may be prescribed to treat or prevent infection. Be sure to follow the instructions
of your dentist or endodontist carefully. After-effects of treatment are minimal, generally lasting from a couple of days to
about a week. It is normal to have some minor discomfort after treatment including slight soreness that can usually be
managed with over-the-counter (aspirin, ibuprofen) medications or prescription (codeine-type) drugs, or a combination of the
Root canal filling material (gutta percha) is placed in the canals and the tooth is sealed with a
temporary filling to protect it from contamination. Then a crown is usually placed over the
tooth to seal and protect it from recontamination and future damage.
Step 10
Your tooth will need a permanent restoration — a filling or a crown — to replace lost tooth structure, and provide a
complete seal to the top of the tooth. Your endodontist will send you back to your general dentist to determine which type of
restoration is best for you. This step is of particular importance since many studies show that if the filled root canals are
recontaminated with bacteria from the mouth, there could be a recurrence of infection around the tooth.
Laws of:
O Law of Centrality –floor of pulp chamber always at center of tooth at level of CEJ.
O Law of Concentricity–external root surface anatomy reflects intern al pulp chamber anatomy.
O Law of the CEJ – distance of external surface of clinical crown vs wall of pulp chamber is the same
throughout the circumference of tooth at level of CEJ.
o CEJ–most consistent repeatable landmark for locating pulp chamber.
o1st Law of Symmetry– except for Mx molars, canal orifices are equidistant from line drawn mesio/disto
across center of pulp chamber floor.
o 2nd Law of Symmetry – except for Mx molars, canal orifices lie on line perpendicular to above line.
o Law of Color Change – pulp chamber floor always DARKER than the walls.
o 1st Law of the Orifice– orifices of the canals ALWAYS located at junction of walls and the floor.
o 2nd Law of the Orifice– orifices of the canals ALWAYS located at the angles in the floor-wall junction.
o3rd Law of the Orifice – orifices of the canals ALWAYS located at terminus of roots developmental fusion
Accessing Teeth opining:
- Mx Incisors – always 1 root 1 canal
o Young patients = triangular, older patients = ovoid
- Mx canines – always 1 root 1 canal
o Ovoid
o In middle 1/3 of lingual surface
- Mx Premolars
o Outline form ovoid facial/lingual
o Mesial concavity at CEJ
o When 2 canals are present, under B and L cusps
- Mx Molars
o Outline form triangular in mesial ½ of tooth
- Base = facial, apex = lingual
o Oblique ridge left intact (usually)
o MB canal slightly distal to MB cusp tip, broad B/L, may have MB2 canal
- MB2 canal 1-3mm lingual to MB1, slightly mesial to line drawn from MB1 to PC
o DB canal distal and slightly lingual to main MB canal, in line with buccal groove
o P canal slightly distal to ML cusp tip, largest canal
- Mn incisors – 25-40% have 2 canals
- Facial easier to locate, generally more straight
- Lingual often shielded by a lingual shelf
o Outline form, shape, and access similar to Mx incisors
Mn canines – 30% have 2 canals
o Ovoid
o Middle 1/3 of lingual surface
- Mn Premolars – 25% have 2 canals
o Ovoid B/L
o Buccal to central groove
- Mn Molars – 30-40% chance 2nd canal in distal root
o Rectangular
o MB canal slightly distal to MB cusp tip
o ML canal orifice in area of central groove, slightly distal compared to MB canal.
Endodontic Radiographs
- Periapicals – diagnostic radiographs, working radiographs, post-op radiographs
- Bitewings (vertical) – RESTORATIVE ASSESSMENT, caries ID, location of pulp chamber, vertical defects
- Pan, occlusal, CBCT – difficult diagnosis, presurgical treatment planning for assessment of vital structures
- FMX – history of teeth (restorations, PA lesion progression, etc)