ENDO Basic Endodontic Treatment Procedures Flashcards
what are the 4 objectives of nonsurgical endodontics?
- to alleviate and prevent future adverse clinical symptoms
- to debride and shape the root canal
- to create the radiographic appearance of a well-obturated root canal system where the root canal filling extends as close as possible to the apical constriction
- the maintain health and/or promote healing and repair of periradicular tissues
what is the most important phase of the technical aspects of root canal treatment?
access preparation
proper access preparation maximizes what 3 things?
cleaning, shaping, and obturation
what are the 3 objectives of access preparation?
straight-line access, conservation of tooth structure, and unroofing of the chamber to expose orifices and pulp horns
straight line access requires adequate tooth structure removal and improves what aspects of access preparation?
- improved instrument control, with less zipping, transportation, or ledging
- improved obturation
- decreased procedural errors, such as ledges or perforations
how does conservation of tooth structure improve RCT outcomes?
minimal weakening of the tooth and prevention of accidents
how does unroofing the chamber to expose orifices and pulp horns aid in access preparation?
- maximum visibility
- prerequisite in locating orifices of canals
- improved straight line access
- exposure of pulp horns
what are the techniques for determining working length?
- estimate WL with a diagnostic film taken using a paralleling technique with a #10 or 15 k file
- correct WL by measuring the discrepancy between the radiographic apex and tip of file; adjust to 1mm short of radiographic apex
- use apex locator (operates on the principles of resistance, frequency, or impedance)
- tactile sensation (often unreliable)
what is the best indicator of clean walls?
level of smoothness obtained
taper of the canal permits what 3 things?
debridement of apical canal, reduces overinstrumentation of the foramen, and improves ability to obturate
what are the 3 cleaning and shaping techniques?
- crown-down
- step-back
- hybrid
which cleaning and shaping technique involves the clinician passively inserting a large instrument into the canal up to a depth that allows easy progress. the next smaller instrument is used to progress deeper into the canal, and the third instrument follows. this continues until the apex is reached. hand and rotary instruments may be used in this technique
crown down
which cleaning and shaping technique involves working lengths that decrease in a stepwise manner with increasing instrument size
step back
which cleaning and shaping technique involves the combination of crown down and step back?
hybrid
___ help confine instruments, materials, and chemicals to the canal space and create a barrier against which gutta percha can be condensed
apical stops
what denotes the file size at the tip of the file?
D1 (ex. 0.08mm for a size 8 file, 0.15mm for a size 15 file)
what denotes the diameter of the file where the cutting flutes end?
- D2 or D16 (flutes end at 16mm)
- it is the diameter at the tip plus 0.32mm (ex. for a 0.02 taper #8 file, it is 0.08mm + (16mm x 0.02mm) = 0.40mm)
what is sodium hypochlorite used for in endodontics?
- irrigation
- disinfection of root canals - hypochlorite anion
- dissolving organic matter - proteolytic material
does sodium hypochlorite remove the smear layer?
no
concentrations of sodium hypochlorite vary from ___ to ___
0.5% to 6%
what are the signs and symptoms of a sodium hypochlorite accident?
- instant extreme pain
- excessive bleeding from the tooth
- rapid swelling
- rapid spread of erythema
- later - bruising and sensory and motor nerve deficits
what is the treatment for a sodium hypochlorite accident?
- long lasting local anesthetic
- encourage drainage
- steroids
- cold compresses
- antibiotics
- analgesics
- daily follow up
what does EDTA stand for?
- ethylenediamine tetraacetic acid
- contains 17% EDTA
what are the indications for EDTA?
- irrigation
- removes inorganic material
- removes smear layer
___ is a synthetic cationic hydrophobic and lipophilic molecule
chlorhexidine
what is the mode of action of chlorhexidine?
interacts with phospholipids and lipopolysaccharides on the cell membrane of bacteria and enters the cell by changing osmotic equilibrium
chlorhexidine is effective at what concentration?
2%
the combination and chlorhexidine and ___ forms an undesirable precipitate, parachloroaniline, which is believed to affect the seal of root canal filling
sodium hypochlorite
___ is the best intracanal medicament available
calcium hydroxide
which characteristic of calcium hydroxide causes an antibacterial effect?
its high pH (12.5)
calcium hydroxide inactivates ___ and has ___ capacity
inactivates lipopolysaccharides and has tissue-dissolving capacity
what are the main purposes of obturation?
- to eliminate all avenues of leakage from the oral cavity or the apical tissues into the root canal system
- to seal within the system any irritants that cannot be fully removed during canal cleaning and shaping procedures
what are the 5 advantages of gutta percha?
- plasticity
- easy to manage
- little toxicity
- easy to remove
- self-sterilizing (does not support bacterial growth)
what are the 4 disadvantages of gutta percha?
- gutta percha without sealer does not seal well
- lack of adhesion to dentin
- elasticity causes rebound to dentin
- shrinkage after cooling
___ is a surgical perforation of the alveolar cortical bone to release accumulated tissue exudates
trephination
what are the objectives of incision and drainage?
evacuate exudates and purulence and toxic irritants
removal of pus during incision and drainage procedures speeds ___ and reduces ___
speeds healing and reduces discomfort from irritants and pressure
what is the best treatment for swelling from acute apical abscess?
establish drainage and to clean and shape the canal
what are the 3 indications for incision and drainage?
- if a pathway is needed in soft tissue with localized fluctuant swelling that can provide necessary drainage
- when pain is caused by accumulation of exudates in tissues
- when necessary to obtain samples for bacteriologic analysis
what are the 3 indications for trephination of hard tissues?
- if a pathway is needed from hard tissue to obtain necessary drainage
- when pain is caused by accumulation of exudate within alveolar bone
- to obtain samples for bacteriologic analysis
___ is a surgical opening created in soft tissue for the purpose of releasing exudates or decompressing an area of swelling
incision and drainage
why is it difficult to achieve profound anesthesia in the presence of an infection?
because of the acidic pH of the abscess and hyperalgesia (increased sensitivity to pain)
when performing an incision and drainage procedure, the incision should be made firmly through ___ to ___
periosteum to bone
when performing an incision and drainage procedure, vertical incisions are typically made because ___
they are parallel with major blood vessels and nerves and leave very little scarring
incision and drainage and trephination procedures may include the placement and subsequent timely removal of a ___
drain
when are antibiotics indicated after incision and drainage and trephination procedures?
in patients with diffuse swelling (cellulitis), patients with systemic symptoms, or patients who are immunocompromised
what are the indication for root end resection (apical surgery or apicoectomy)?
- persistent or enlarging apical pathosis after nonsurgical endodontic treatment
- nonsurgical endodontics is not feasible
in what cases is nonsurgical endodontics not feasible and thus root end resection is indicated?
- marked overextension of obturating materials interfering with healing
- biopsy is necessary
- access for root end preparation and root end filling is necessary
- the apical portion of the root canal system with apical pathosis cannot be cleaned, shaped, and obturated
what are the contraindications for root end resection?
- anatomic factors such as a thick external oblique ridge or proximity of the neurovascular bundle
- medical or systemic complications
- nonrestorability
- poor root/crown ratio
___ is the preparation of a flat surface by the excision of the apical portion of the root and any subsequent removal of attached soft tissues
root end resection (apical surgery or apicoectomy)
what are the basic steps for the root end resection procedure?
- cut/elevate mucoperiosteal flap and remove bone if necessary
- root end resection
- root end filling (retrofilling)
- primary closure of surgical site
what are the common flap designs used for root end resection?
- submarginal curved flap (semilunar flap)
- submarginal triangular and rectangular flaps
- full mucoperiosteal flap
what are the disadvantages of the submarginal curved flap (semilunar flap) in relation to root end resection?
- restricted access with limited visibility
- leaving the incision directly over the lesion
- often healing with scarring
during root end resection, how many mm of the diseased root tip should be removed, and at what degree bevel?
3mm of disease root tip is removed at a 0-10 degree bevel (as opposed to the traditional 45 degree bevel)
during root end resection, ___mm of the root end should be left for cavity preparation and root end filling
3mm
during root end resection, how is the root end cavity prepared?
with ultrasonic instrumentation
during root end resection procedures, what can increase apical leakage of the filling material?
increasing the bevel
during root end resection procedures, what can decrease apical leakage of the filling material?
increasing the depth of root end filling (at least 3mm)
describe the root end filling (retrofilling) step of root end resection. what material is commonly used?
a biologically acceptable filling material, such as mineral trioxide aggregate (MTA) is placed into the 3mm root end preparation to seal the root canal system
___ is the surgical division (in approximately equal halves) of a multirooted tooth, where a vertical cut is made through the crown into the furcation and the defective half of the tooth is extracted
hemisection
what are the 6 indications for hemisection?
- class III or IV periodontal furcation defect
- infrabony defect of one root of a multirooted tooth that cannot be successfully treated periodontally
- coronal fracture extending into the furcation
- vertical root fracture confined to the root to be separated and removed
- carious, resorptive root or perforation defects that are inoperable or cannot be corrected without root removal
- persistent apical pathosis in which nonsurgical treatment or apical surgery is impossible and the problem is confined to one root
hemisections are most often performed on which teeth?
mandibular molars
hemisection requires ___ on all retained root segments
RCT
when hemisection is indicated, should RCT and permanent restoration into the canal orifices be performed before or after hemisection?
before when possible
___ is a surgical division (like hemisection; usually a mandibular molar) but the crown and root of both halves are retained
bicuspidization
what is the end result of bicuspidization?
complete separation of the roots and creation of two separate crowns
___ is removal of one or more roots of a multirooted tooth
root resection (root amputation)
what are the 7 indications for root resection?
- class III or IV periodontal furcation defect
- infrabony defect of one root of a multirooted tooth that cannot be successfully treated periodontally
- existing fixed prosthesis
- vertical root fracture confined to the root to be resected
- carious, resorptive root or perforation defects that are inoperable or cannot be corrected without root removal
- persistent apical pathosis in which nonsurgical root canal treatment or apical surgery is impossible
- at least one root is structurally sound
root resection requires ___ on all retained root segments
RCT
___ is the insertion of a tooth into its alveolus after the tooth has been extracted for the purpose of accomplishing a root end filling procedure
intentional reimplantation
what are the 5 indications for intentional reimplantation?
- persistent apical pathosis after endodontic treatment
- nonsurgical retreatment is impossible or has an unfavorable prognosis
- apical surgery is impossible or involves a high degree of risk to anatomic structures
- the tooth presents a reasonable opportunity for removal without fracture
- the tooth has an acceptable periodontal status before the reimplantation procedure
during intentional reimplantation, ___ of the reimplanted tooth may or may not be needed
stabilization
in intentional reimplantation procedures, ___ is performed before reimplantation
RCT
when is surgical removal of of the apical segment of a fractured root indicated?
when a root fracture occurs in the apical portion and pulpal necrosis results
when surgical removal of the apical segment of a fractured root is indicated, the fractured segment may be removed surgically after or in conjunction with ___
nonsurgical RCT
what are the 3 indications for surgical removal of the apical segment of a fractured root?
- root fracture in the apical portion of the root
- pulpal necrosis in the apical segment as indicated by an apical lesion or clinical signs or symptoms
- coronal tooth segment is restorable and functional
describe the surgical removal of the apical segment of a fractured root procedure
- a mucoperiosteal flap is surgically elevated and, when necessary, bone is removed to allow direct visualization and access to the affected site
- the apical portion of the affected root and all of the targeted tissues are removed
endodontic emergencies are usually associated with ___ and/or ___ and require immediate diagnosis and treatment
pain and/or swelling
endodontic emergencies are usually caused by ___ or ___
pathoses in the pulp or periapical tissues
endodontic emergencies include what 3 things?
luxation, avulsion, or fractures of the hard tissues
which type of endodontic emergency is often referred to as a “flare up”?
an emergency that occurs between appointments or after obturation (these are easier to manage because the offending tooth has been identified and diagnosed)
what is the immediate goal of endodontic emergency treatment?
reducing the irritant through reduction of pressure or removal of the inflamed pulp or apical tissue (pressure release is more effective than pulp or tissue removal in producing pain relief
in the management of painful irreversible pulpitis, what is the preferred treatment?
complete cleaning and shaping of the root canals
in the management of painful irreversible pulpitis, ___ provides the greatest pain relief, but ___ is usually effective in the absence of percussion sensitivity
pulpectomy, pulpotomy
in the management of painful irreversible pulpitis, do chemical medicaments sealed in chambers help control or prevent additional pain?
no
are antibiotics generally indicated in the management of painful irreversible pulpitis?
no
reducing ___ has been shown to aid in the relief if symptoms of symptomatic apical periodontitis exist
occlusion
describe how treatment of pulpal necrosis with apical pathosis is twofold
- remove or reduce pulpal irritants
2. relieve apical fluid pressure when possible
in the management of pulpal necrosis with apical pathosis, what is the treatment of choice when no swelling exists?
complete canal debridgement
in the management of pulpal necrosis with apical pathosis, when localized swelling exists, it indicates that the abscess has ___
invaded soft tissues
what is the treatment of pulpal necrosis with apical pathosis when localized swelling exists?
- complete debridement
- drainage to relieve pressure and purulence (drainage through tooth or mucosa)
are antibiotics indicated for patients with pulpal necrosis with apical pathosis when localized swelling exists?
antibiotics are generally unnecessary because patients with localized swelling seldom have elevated temperatures or systemic signs
in cases of pulpal necrosis with apical pathosis, when diffuse swelling exists, in indicates that the swelling has ___
dissected into fascial spaces
what is the treatment for pulpal necrosis with apical pathosis when diffuse swelling exists?
- most important is the removal of the irritant via canal debridement or extraction of the offending tooth
- swelling may be incised and drained followed by drain insertion for 1-2 days
- systemic antibiotics are indicated
are flare ups a true emergency? what is the treatment?
- yes and they are so severe that an unscheduled visit and treatment is required
- treatment generally involves complete cleaning and shaping of canals, placement of intracanal medicament, and prescription of analgesic
what is the best predictor of flare up emergencies?
a history of preoperative pain or swelling
is there a relationship between flare ups and treatment procedures (single or multiple visits)?
no
are antibiotics indicated for flare ups?
generally no, except in the instance of systemic symptoms and cellulitis
what are 3 types of sterilization appropriate for endodontic instruments?
- gluteraldehyde
- pressure sterilization
- dry heat sterilization
gluteraldehyde sterilization is appropriate for what materials?
cold or heat labile instruments such as rubber damn frames
how long should instruments be immersed in gluteraldehyde to achieve cold sterilization?
24 hours
immersion sterilization (gluteraldehyde) is effective for ___ but it fails to ___
effective for disinfection but it fails to kill all organisms
why is gluteraldehyde the least desirable sterilization method?
because this method is not presently verifiable with biologic indicators, and should be reserved only for instruments that cannot withstand heat
describe pressure sterilization (time, temperature, pressure)
instruments are wrapped and autoclaved for 20 minutes at 121 *C and 15 psi
what does pressure sterilization kill?
all bacteria, spores, and viruses
either ___ or ___ can be used in pressure sterilization
steam or chemicals
pressure sterilizers that use chemicals rather than water have the advantage of ___
causing less rusting
what is the disadvantage of steam and chemical autoclaving?
they both dull the edges of all cutting instruments owing to expansion with heat and contraction with cooling, resulting in permanent edge deformation
___ sterilization is superior for sterilizing sharp-edged instruments
dry heat
describe dry heat sterilization (time and temperature)
- the cycle time is temperature dependent
- after the temp reaches 160 *C, the instruments should be left undisturbed for 60 minutes
- if the temp decreases to less than 161 *C, the full 60-minute heat cycle must be repeated
what is the disadvantage of dry heat sterilization?
the substantial time required both for sterilization and for cooling
how is surface disinfection* during canal debridement accomplished?
- by using a sponge soaked in 70% isopropyl alcohol or proprietary quaternary ammonium solutions
- cleans but does not disinfect*
the most accurate diagnostic radiographs are made using a ___ technique
- paralleling
- less distortion, more clarity, and reproducibility of the film
if the paralleling technique cannot be used, what is the next best technique for diagnostic radiographs?
- modified paralleling technique
- the film is not parallel to the tooth, but the central beam is oriented at right angles to the film surface
what is the least accurate diagnostic radiograph technique?
bisecting angle
what are the 3 working films taken during a normal endodontic procedure?
working length image, master cone image, and check image (taken of master cone with accessory cones before searing off the excess gutta percha during cold lateral obturation)
the optimal setting for maximal contrast between radiopaque and radiolucent structures is ___
70 kV
___ reveals third dimension of the structures
cone image shifting
what are the indications and advantages of cone image shifting?
- separation and identification of superimposed canals
- movement and identification of superimposed structures
- determination of WL
- determination of curvatures
- determination of faciolingual location
- identification of undiscovered canals
- location of calcified canals
in general, if a root contains only a single canal, that canal will be positions close to the ___ of the root
center
cone image shifting radiographs must be taken at either a mesial or distal angulation to see if ___
another canal is present
T or F:
a root always contains a canal, however tiny or impossible to negotiate (as in the case of calcified canals, which are frequently not visible on radiographs)
true
when searching for an elusive canal, ___ must be made
two working radiographs (one from a straight view, and the other from either a mesial or distal view)
what are the disadvantages of cone image shifting?
decreased clarity and superimposition of structures
what are the limitations of endodontic radiographic anatomy?
- a considerable amount of bone must be resorbed before a lesion becomes visible radiographically
- periapical lesions become more evident if cortical bone is resorbed
what are the 4 characteristics of radiolucent lesions?
- apical lamina dura is absent
- most often, radiolucency is seen to be circular about the apex, but lesions may have various appearances
- the radiolucency stays at the apex regardless of cone angulation
- a cause of pulpal necrosis is usually evident
what are the characteristics of radiopaque lesions?
- the radiopaque appearance is one of diffuse borders and a roughly concentric arrangement around the apex
- condensing osteitis and apical periodontitis frequently manifest together
- the pulp is often vital and inflamed
radiopaque lesions are better known as ___ or ___
focal sclerosing osteomyelitis or condensing osteitis
histologically, radiopaque lesions represent an increase in ___
trabecular bone
what are the 4 portals of entry of bacteria into the pulp?
- caries
- permeable tubules
- cracks or trauma
- pulp exposure
how can bacteria access the pulp through dentinal tubules?
cavity preparation, exposure of dentin, leaking restorations
T or F:
neither dentinal fluid nor odontoblastic processes are present in necrotic pulp
true
there is a positive correlation between the number of bacteria in an infected root canal and the ___
size of the apical radiolucency
describe the bacteria present in primary endodontic infections
- strict anaerobes predominate
- gram negative anaerobic - black pigmented bacteroides (prevotella nigrescens, porphyomonas) most common in endodontic infections
- gram positive anaerobic - actinomyces (root caries)
describe the bacteria present in unsuccessful root canal therapy
- enterococcus faecalis (rarely found in infected but untreated root canal)
- high incidence of facultative anaerobes
what are lipopolysaccharides, and what is their role in endodontic infections?
- found on the surface of gram negative bacteria
- when released from the cell wall, lipopolysaccharides are known as endotoxins, which is capable of diffusing across dentin and contributes to apical inflammation
what are the first choice antibiotics used in endodontics?
penicillin V or amoxicillin
penicillin V and amoxicillin are effective against which bacteria?
- most strict anaerobes (prevotella, prophyromonas, peptostreptococcus, fusobacterium, and actinomyces)
- gram positive facultative anaerobes (streptococci and enterococci) in polymicrobial endodontic infections
other than penicillin V and amoxicillin, what are two other antibiotics used in endodontics?
- clindamycin and metronidazole*
- *metronidazole must be combined with another antibiotic
clindamycin is effective against what bacteria?
many gram negative and gram positive organisms, including strict and facultative anaerobes
metronidazole is effective against what bacteria?
- strict anaerobes
- it is ineffective against facultative anaerobes and aerobes, so it must always be used in combination with another antibiotic, such as amoxicillin
