Endodontics

Question 1

Pulpal Inflammation (not infection)

Answer 1

• Insidious process
• No direct insult to pulp, thus chronic infection (no PMN, only plasma cells, lymph, MO)
• Most common and earliest symptom: thermal sensitivity (NOT percussion, throb, or persistent discomfort) due to dentin involvement!

If pulp was exposed, then an acute run occurs

Question 2

Vital vs non-vital pulp and bacteria

Answer 2

• Vital pulp can withstand bacteria invasion during an exposure (in 2 weeks, only 2 mm of coronal pulp is infected)
• Non-vital pulp is a fertile ground

Question 3

CaOH pH

Answer 3

pH = 12.5

- leads to necrosis. This necrosis is meant to cause hard tissue repair with odontoblasts laying down reparative dentin.

Question 4

Chronic apical abscess vs cyst or granuloma

Answer 4

cyst or granuloma have a defined radiolucent border
All are asymptomatic

NOTE: Tx for Acute Abscess is I&D first, then return for RCT to provide patient comfort. In Chronic Abscess, no need to I&D b/c patient is asymptomatic.

Apical Trephination = taking a 15 file and making a fistula through he soft tissue via the canals and extend past the apex

Surgical Trephination = perforating the bone with a round bur to make a fistula

Question 5

Thermal test

Answer 5

Lingering if over 15 sec

COLD

1. cold water bath
2. ice or CO2 sticks
3. ENDO ice = DDM (dichlorodifluoromethane)
4. Ethyl Chloride

HOT

1. Gutta percha
2. hot water bath
3. rubber wheel with a hand piece

NOTE: trauma teeth may develop PA radiolucencies later on, but can still be vital!

EPT

• contraindicated with pacemakers
• False (+) = pus, nervous patient, moisture
• False (-) = trauma, open apex, restorations which insulate, analgesic Rx.
• A low reading will be seen with reversible pulpitis

An EPT only determines that some A delta fibers are still active, not about vasculature. Some necrotic pulps will have firing A delta fibers.

Question 6

Internal vs External resorption

Answer 6

Internal (PINK TOOTH)

• Asymptomatic, incidental finding
• From inflammation due to infected pulp from trauma
• Pulp must be vital for this to occur, however, pulp test may be negative.
• CAUSES: Trauma (pulpal), decay, CaOH direct pulp cap, cracked tooth
• NOTE: an x-ray may show an external (cervical) reposition as an internal one, so take a different angle x-ray

External = cervical resorption (if located at CEJ)

• CAUSES: Trauma (PDL), PA inflammation, excessive ortho forces, tooth impaction, internal bleaching
• Seen as Bowl-shaped areas of resorption involving cementum and dentin
• Tx: RCT. Obtruded with CaOH and replaced every 3 months for 1 year. May continue with permanent gutta percha if resorption has stopped.

Question 7

Types of resorption

Answer 7

1. Replacement = progressive ankylosis due to excessive trauma to the PDL apparatus (no PDL or commute layer is present between dentin and bone)

SIGNS: No mobility, metallic sound to percussion, infra-occlsuion in a developing dentition.

MOST common in unsuccessful replant cases

2. Surface = Acute (not progressive) injury to PDL.
   - Self limiting to cementum
   - Reversible
   - Not seen radiographically

Question 8

Pulp cells, fibers and layers

Answer 8

Type 1 > Type 3 collagen&raquo_space; Type 5 collagen

• Dentin has [Type 1]
• Odontoblast make Type 1
• [Fibroblasts] make both Type 1 and 3
• Histiocytes (MO), ymphocytes

FIBERS:
1. myelinated = sensory = A delta (enter at apex then forms the plexus of Raschkow. In the plexus, it becomes unmyelinated) = quick, sharp, monetary pain that does not linger. A delta fibers + odontoblast layer = pulpodentinal complex. A-delta fibers are tested with EPT tests (no cardiac pacemaker!)

2. unmyelinated = motor (vasodilation) = C-fibers = enter with the A-delta fibers at apex and are though out the pulp = burning, ache, throb = high threshold = noci-ceptive fibers (pain to prevent injury) = excitable even in necrotic tissue = stimulated by HEAT = shows irreversible local damage.
3. free NERVE ENDING = pain (thus, regardless of pressure, hot or cold, response is always pain)
4. Reticular fibers = decrease with age
5. Collagen fibers = increase with aged to calcifications

ZONES: inner to outer
1. central zone = pulp proper (Large BV, nerves)
2. cell rich (fibroblasts)
3. cell free = zone of weil (capillaries and Raschkow nerve plexus)
4. Odontoblastic layer
(next layer is predentin which is unmineralized and predisposes denin to internal resorption)

• Primary pulp function is formation of dentin via induction (forms dentin which forms enamel) and nutrition.
• Pulp lacks collateral circulation (thus is prone to necrosis)

Question 9

Dentin types

Answer 9

1. Mantle = first formed before odontoblast layer is organized
2. Circumpulpal = most dentin
3. Secondary = Forms after tooth eruption and throughout life –> asymmetric, irregular reduction in pulp size as a person ages
4. Tertiary = reparative = irregular, disorganized due to stimuli
5. Pre-dentin = not mineralized, 47 microns right near the pulp

Primary dentin = forms prior to apex closure
secondary = after closure
Junction between the two shows a sharp change in direction of the dentinal tubles.

Question 10

Pulp Stone

Answer 10

Chronic result of stimulus (decay or large restoration)

Question 11

Tx of perforations

Answer 11

control heme (NOT with formecresol) –> temporarily seal (Cavit, ZOE, decal = if its so large) –> continue with RCT –> Restore later

If sub-crestal, seal first to prevent leakage into tooth.

Question 12

Vertical root fracture

Answer 12

• x-rays show a radiolucent halo uniformly surrounding the entire root
• Clinical exam will show a persistent periodontal defect
• Most are due to iatrogenic causes

NOTE: Horizontal fractures do not automatically require RCT is asymptomatic and no pulp necrosis.

Question 13

Problem with endodontic implants?

Answer 13

no apical seal

Question 14

What is root submersion used for?

Answer 14

maintain bone height (RCT roots are submerged and full thickness flap laid over top)

Question 15

When does the apex of a tooth close?

Answer 15

2-3 years post eruption

Question 16

What is the sequela of PA infection?

Answer 16

osteomyelitis (rare)

• Tends to be more diffuse in the mandible than the maxilla
• Acute onset with pain, fever
• X-ray shows “moth eaten” pattern
• Tx: I&D, Antibiotics

Question 17

Retrofill materials (places an apical seal, post apicoectomy, used in calcified canals that cannot be shaped)

Answer 17

1. MTA (mineral trioxide aggregate)
   - Ca + P
   - High pH –> hard tissue induction
   - PRO: Biocompatible, good seal
   - CON: difficult to manipulate, sets too long
2. zinc free amalgam

Question 18

Most common cause of reverse fill/retrograde fill endo?

Answer 18

Current post in a tooth that needs re-treatment.

Question 19

Periodontal abscess

Answer 19

will respond (+) with pulp vitality (unlike an apical abscess)
(+) percussion, (+) palpation

Question 20

Canal shapes with files

Answer 20

reaming (repeated rotation) action

• makes a rounded canal shape
• engine driven files only use this motion
• silver fill cones

filing (push and pull, scrape walls) action

• irregular shape
• removes dentin
• Gutta percha

circumferential filing = best way to prevent ledges

Question 21

Obturation should end where (be the narrowest)?

Answer 21

Dentin-cementum junction which is 0.5 - 1.0 mm from apical foramen

Question 22

Endo Sealer Types:

Answer 22

1. ZOE = biocompatible with soft tissue. But causes staining, slow setting, non-adhesive and is soluble.

Question 23

Most common cause of RCT failure?

Answer 23

incomplete disinfection of the canals

2nd cause: leakage in an incompletely obturated canal

NOTE: Most teeth with RCT are lost due to restorative failure, not the RCT itself

If you see a PA region grow after removal of the granuloma/cyst and RCT, its due to leakage.

Question 24

Chelators

Answer 24

1. 17% EDTA
   - remove mineralized portion of smear layer (calcified tissue only, thus safe for ST)
   - opens dentinal tubules
   - works for 5 days until the chelator is used up, thus must be irrigated when canal shaping is done
   - Replaced Ca with Na to make softer canals for proper enlargement
2. EDTAC (Cetavlon)
   - Has greater anti-microbial potential, but is more inflammatory than EDTA
   - NaOCl is the inactivator
3. RC-Prep
   - EDTA + Urea Peroxide (Irrigation)

Question 25

chloroform in Endo

Answer 25

dissolve gutta percha during re-treatment and on solvent-softened custom cones

Question 26

Irrigants

Answer 26

1. 5.25% NaOCl = toxic to vital tissue 2. 3% H2O2 = effervescent effect 3. Urea Peroxide = tolerated by ST more than NaOCl, and greater solvent/germicidal action than H2O2.

Question 27

Internal bleaching

Answer 27

1. 30% H2O2 in alkaline medium 2. Walking black = sodium perborate with water = kept in patient's tooth for 4-5 days with a temporary restoration, removed and process repeats. Safer than Superoxol. 3. 30% Superoxol = potent oxidized of stain-producers 4. Chairside: Heat + Superoxol = Heat liberates the oxygen Bleach changes enamel and dentin color RISK: External = Cervical root resorption. Recalls are a must to monitor after bleaching. Acute apical periodontist if canals are not fully obturated Other tooth whitening: Chair-side: 35% H2O2 light-activated in 4-10 minute cycles Rx: 10% Carbamide Peroxide OTC: H2O2 - Can go into dentin - Worst response Grey (tetracycline → use composite) - Extrinsic Stains = Chromogenic bacteria in plaque , tea, tobacco, amalgam - Intrinsic Stains = tetracycline, fluoride, dentogenesis imperfect - WATER PICKS remove non-adherent bacteria better than brushing

Question 28

What are the only 2 health contraindications for RCT?

Answer 28

1. Uncontrolled diabetes | 2. Very recent MI (6 months)

Question 29

Best prognosis for root fractures

Answer 29

Horizontal > Vertical Apical root > midroot > coronal root Oblique > Transverse

Question 30

Why are endo teeth weak?

Answer 30

Not because they are brittle (actually stay moist up to 10 years), but bc of loss of tooth structure

Question 31

Pulp chamber retained amalgam requires ___ mm of amalgam in each canal for retention.

Answer 31

3 mm in each canal

Question 32

Patient recently received on inlay and has pain on biting. Occlusion is good, but painful.

Answer 32

Fractured cusp.

Question 33

Pulpal involvement is confirmed, but x-rays do not show an offender. Deep pockets noted.

Answer 33

Vertical root fracture

Question 34

What does 25.02 K file mean?

Answer 34

``` D1 = where cutting blades begin D2 = where the flutes that extend up the shaft for 16 mm come to a stop (Length of cutting edges are always 16 mm) ``` A 0.02 taper file increases in diameter by 0.02 mm every millimeter up from the tip Ex: 25.02 file means - 0.25mm at the tip (D1) - 0.27mm for 1 mm up from the tip, 0.29mm for 2 mm up from the tip, etc. - Total cutting length is 16 mm * 15-White * 20-Yellow * 25-Red * 30-Blue * 35-Green * 40-Black * 45-White (color sequence repeats as you increase in size)

Question 35

Zones of Carious Dentin

Answer 35

1. Normal Dentin 2. Subtransparent Dentin: demineralized from acid, but not infected with bacteria and is capable of remineralization 3. Transparent Dentin: softer, but otherwise exactly the same as sub transparent dentin. No need to remove. 4. Turbid Dentin: bacterial invasion, not capable of remineralization 5. Infected Dentin: outermost zone that is decomposed dentin.

Question 36

Zones of Incipient lesions

Answer 36

1. Surface: unafected 2. Body: largest portion. Demineralized 3. Dark: no polarized light. Demineralized + Mineralized area 4. Translucent: Deepest zone, advancing front of decay