Endodontics, Preparation for NBDE Part II

  • Category: Endodontics
  • Aim: Revising for NBDE Part II
  • Questions: 54
  • Hint: No
  • Mutiple Opportunites: No
  • Time Limit: No
  • Answer Explaining: Yes
Updated 11/4/2012, more 30 questions

Endodontics

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Question 1
Aqueous EDTA is primarily used to ____.
A
Dissolve organic matter
B
Dissolve inorganic matter
C
Kill bacteria
D
Prevent sealer from extruding out of the canal space
Question 1 Explanation: 
B. EDTA Is the chelating solution customarily used in endodontic treatment. Chelators remove inorganic components, leaving the organic tissue elements Intact.
Question 2
A noncarious tooth with deep periodontal pockets that do not involve the apical third of the root has developed an acute pulpitis. There is no history of trauma other than a mild prematurity in lateral excursion. What is the most likely explanation for the pulpitis?
A
Normal mastication plus toothbrushing has driven microorganisms deep into tissues with subsequent pulp involvement at the apex.
B
During a general bacteremia, bacteria settled in this aggravated pulp and produced an acute pulpitis.
C
Repeated thermal shock from air and fluids getting into the deep pockets caused the pulpitis.
D
An accessory pulp canal in the gingival or the middle third of the root was in contact with the pockets.
Question 2 Explanation: 
D. Periodontal disease can have an effect on the pulp through dentinal tubules, lateral canals, or both. Primary periodontal lesions with secondary endodontic Involvement differ from primary endodontic-secondary periodontic lesions in their temporal sequence. Primary periodontal problems have a history of extensive periodontal disease.
Question 3
Which of the following best describes the anesthetic effects of a posterior superior alveolar nerve block?
A
Pulpal anesthesia of the maxillary second and third molars.
B
Pulpal anesthesia of the maxillary first molar.
C
Pulpal anesthesia of the maxillary first and second premolars.
D
Pulpal anesthesia of the second premolar.
Question 3 Explanation: 
A. Pulpal anesthesia of the maxillary second and third molars. Posterior superior alveolar nerve block anesthetizes the entire second and third maxillary molars; the first maxillary molar fully anesthetized in about 70% of patients and partially anesthetized (except for mesiobuccal root) in about 30%. This block is highly effective but carries significant risk of hematoma, so frequent aspiration during injection is crucial.
Question 4
Which of the following statements best describes treatment options for a separated instrument at the initiai stage of cleaning and shaping?          
A
Immediate attempt to remove the instrument.
B
Stop canal instrumentation, do not attempt removal, and obturate.
C
Attempt to bypass the obstructed instrument.
D
Both A and C are options.
Question 4 Explanation: 
D. Both A and C are options. There are basically three approaches for the treatment of separated instruments: (1) attempt to remove the instrument, (2) attempt to bypass it, and (3) prepare and obturate to the segment. Using a small file and using the guidelines for negotiating a ledge, attempt to bypass the separated instru-ment. If this is successful, broaches or Hedstrom files are used to try to grasp and remove the segment. Then the canal is cleaned, shaped, and obturated to its new working length. If the instrument cannot be bypassed, preparation and obturation should be performed to the coronal level of the fragment.
Question 5
On a radiograph, the facial root of a maxillary first premolar would appear distal to the lingual root if the ____.
A
Vertical angle of the cone was increased
B
Vertical angle of the cone was decreased
C
X-ray head was angled from a distal position relative to the premolar
D
X-ray head was angled from a mesial position relative to the premolar
Question 5 Explanation: 
D. The buccal object rule [Clark’s rule or “SLOB” rule (Same Lingual, Opposite Buccal) ] is used to identify the buccal or lingual location of objects in relation to a reference object. If the image of the object moves mesially when the x-ray tube is moved mesially, the object is located on the lingual If the image of the object moves distally when the x-ray tube moves mesially, the object is located on the buccal (facial).
Question 6
Zinc oxide eugenol is a good temporary restora­tion because ____.
A
It is less irritating
B
It has increased strength over other restorations
C
It provides a good seal
D
It is inexpensive
Question 6 Explanation: 
C. It is the physical and chemical properties of zinc oxide eugenol that are beneficial in preventing pulpal injmy and in reducing postoperative tooth sensitivity. Importantly, it provides a good biological seal; also, its antimicrobial properties enable it to suppress bacterial growth, thus reducing formation of toxic metabolites that might result in pulpal inflammation.
Question 7

Which of the following most likely applies to a cracked tooth?

A
The direction of the crack usually extends mesiodistally.
B
The direction of the crack usually extends faciolingually.
C
Radiographic exam is the best way to detect it.
D
A and C only.
E
B and C only.
Question 7 Explanation: 
A. The direction of the crack usually extends mesiodistally. Cracks extend deep into the dentin and are usually propagated mesially- distally in posterior teeth, often in the region of the marginal ridge. Dyes and transillumination are very helpful in the visualization of cracks. Unfortunately, it is often impossible to determine how extensive a crack is until the tooth is extracted.
Question 8
Initiai instrumentation in endodontic treatment is done to the level of the.
A
Radiographic apex
B
Dentinoenamel junction
C
Cementodentinal junction
D
Cementopulpal junction
Question 8 Explanation: 
C. Cementodentinal junction. At the apex, or bottom of the tooth, the canal narrows. This narrowing is the cementodentinal junction (CDJ) or the apical constriction. This narrow spot provides a natural stop for debris, irrigation and filling materials from being forced into the periapical tissue. Most dentists will work to clean the canal down to this point in their root canal procedures.
Question 9

Which of the following tests is the least useful in endodontic diagnosis of children?

A
Percussion
B
Palpation
C
Electric pulp test
D
Cold test
Question 9 Explanation: 
C, Electric pulp test. Until apical closure occurs, teeth do not respond normally to electric pulp testing. In addition, a traumatic injury may temporarily alter the conduction capability of nerve endings and/or sensory receptors in the pulp. A patient with a vital pulp may not experience any sensation right after trauma.
Question 10
The apical portion of maxillary lateral incisor usually curves to the ____.
A
Facial
B
Palatal
C
Mesial
D
Distal
Question 10 Explanation: 
D. Studies have shown that as many as 50% of the roots of maxillary lateral teeth were distally dilac- erated. Oversight of the distal direction of root dilaceration of upper lateral Incisors can be a contributing factor In the failure of endodontic treatment of these teeth.
Question 11
A classic teardrop-shaped periradicular lesion on a radiograph can be indicative of a vertical root fracture. The prognosis of a vertical root fracture is hopeless, and the tooth should be extracted.
A
First statement is true, second is false.
B
First statement is false, second is true.
C
Both statements are true.
D
Both statements are false.
Question 11 Explanation: 
C. Both statements are true. Often the radiographic interpretation of a vertical root fracture is the pattern of bone loss occurring in a teardrop¬shaped, J-shaped, or halolike radiolucency, with the bone loss originating apically and progressing coronally up one side of the root. Because vertical root fractures are susceptible to microleakage and because of their compro¬mised internal structure, they have a poor prognosis and should be extracted.
Question 12

Features of focal sclerosing osteomyelitis often include:

A
A nonvital pulp test.
B
A history of recent restoration of the tooth in question.
C
A radiolucent lesion which, in time, becomes radiopaque.
D
None of the choices is true.
Question 12 Explanation: 
B. A history of recent restoration of the tooth in question. Focal sclerosing osteomyelitis (FSO) consists of a localized, usually uniform zone of increased radiopacity adjacent to the apex of a tooth that exhibits a thickened periodontal ligament space or an apical inflammatory lesion. The size of the lesions usually measure less than 1 cm in diameter. There is no radiolucent halo surrounding this type of lesion. The osteitis microscopically appears as a mass of dense sclerotic bone. FSO is most often found in patients younger than 20 years of age, around the apices of mandibular teeth (most commonly molars) with large carious lesions and chronically inflamed pulps or with recent restorations. Most sources agree that the associated tooth may or may not be vital. Gender is not a predisposing factor. FSO can be asymptomatic or the patient can experience mild pain, depending on the cause. FSO is usually discovered upon radiographic analysis. It represents a chronic, low-grade inflammation.
Question 13
Which of the following statements best describes treatment options for a separated instrument (e.g., finger spreader) at the filling stage of treatment?
A
Immediately attempt to remove the instrument.
B
Do not attempt removal and proceed to obturate.
C
Attempt to bypass the obstructed instrument.
D
Both A and C are options.
Question 13 Explanation: 
B. If an instrument is broken at the filling stage, it is not necessary to remove or bypass the instrument because the canal has already been cleaned and shaped. Prognosis depends largely on the extent of undebrided material remaining within the canal Attempt to obturate as much of the canal as possi¬ble.
Question 14

The indications for periradicular surgery include all of the following except which one?

A
Procedural accidents during previous nonsurgical endodontic treatment.
B
Irretrievable separated files in the canals.
C
Failed nonsurgical endodontic treatment and persisting radiolucency.
D
Treatment for a nonrestorable tooth.
Question 14 Explanation: 
D. Treatment for a nonrestorable tooth. Perpe tuation of apical inflammation or infection after nonsurgical root canal therapy is often due to poorly obturated canals, tissues left in the canal, broken instruments, procedural accidents during treatment, or remnants of necrotic tissue in accessory canals. The removal of the apical segment of the tooth via root-end surgery usually removes the nidus of infection. Nonrestorable teeth should be extracted.
Question 15
Once the root canal is obturated, what usually happens to the organism that had previously entered periradicular tissues from the canal?
A
They persist and stimulate formulation of a granuloma.
B
They are eliminated by the natural defenses of the body.
C
They reenter and reinfect the sterile canal unless root-end surgery is performed.
D
They will have been eliminated by various medicaments that were used in the root canal.
Question 15 Explanation: 
B. They are eliminated by the natural defenses of the body. Obturation prevents coronal leakage and bacterial contamination and seals the remaining irritants in the canal. After root canal obturation, the remaining bacteria should have lost their source of nutrition, becoming susceptible to the body’s immune system.
Question 16
Which of the following factors affects long-term prognosis of teeth after perforation repair?
A
Size of the defect.
B
Location of the defect.
C
Time elapsed between the perforation and its repair.
D
All of the choices are true.
Question 16 Explanation: 
D. Factors affecting the long-term prognosis of teeth after perforation repair include the location of the defect in relation to the crestal bone; the length of the root trunk; the accessibility for repair; the size of the defect; the presence or absence of a periodontal communication to the defect; the time lapse between perforation and repair; the sealing ability of the restorative material; and technical skill. Early recognition and repair improve the prognosis. Smaller perforations (< 1 mm) cause less destruction. Subcrestal lesions, especially those closer to the apex, have better prognosis.
Question 17
When compared to the bisecting-angle tech­nique, the advantages of the paralleling tech­nique in endodontic radiology include all of the following except ____.
A
A significant decrease in patient radiation
B
A more accurate image of the tooth’s dimensions
C
That it is easier to reproduce radiographs at similar angles to assess healing after treatment
D
The most accurate image of all the tooth’s dimensions and its relationship to surrounding anatomic structures
Question 17 Explanation: 
A. The paralleling, not right-angle, technique is best for endodontics. The film is placed parallel to the long axis of the tooth and the beam placed at a right angle to the film. The technique allows for the most accurate and reproducible representation of tooth size.
Question 18

Which is not a property of sodium hypochlorite (NaOCl)?

A
Chelation
B
Tissue dissolution at higher concentrations
C
Microbicidal activity
D
Flotation of debris and lubrication
Question 18 Explanation: 
A. Chelation. Sodium hypochlorite is the most widely used irrigant and has effectively aided canal preparation for years. NaOCl is a good tissue solvent as well as having antimicrobial effect. It acts as a lubricant for root canal instrumentation. It is toxic to vital tissue, so always use a rubber dam. Hypochlorite’s antibacterial action is based upon its effects on the bacterial cell wall. Once the cell wall is disrupted, the vital contents of the bacteria are released. The bacterial membrane and intracellular associated functions cease. Sodium hypochlorite is an effective necrotic tissue solvent. NaOCl remains the irrigating solution of choice because it fulfills all the above requirements.
Question 19
What is the radiographic sign of successful pulpotomy in a permanent tooth?
A
Open apex
B
That the apex has formed
C
Loss of periradicular lucency
D
No internal resorption
Question 19 Explanation: 
B. Pulpotomy is normally not recommended in permanent teeth unless root development is incomplete. If incomplete, the calcium hydroxide pulpotomy is recommended. This is performed in permanent teeth with immature root development and with healthy pulp tissue. The success is indicated when the root apex, if not completely formed, completes its full development. This procedure is only done on teeth free of symptoms.
Question 20

Which perforation location has the best prognosis?

A
Coronal third of root
B
Apical third of root
C
Chamber floor
D
Middle third of root
Question 20 Explanation: 
B. Apical third of root. Apical perforations occur through the apical foramen or the body of the root (a perforated new canal). In general, the more subcrestally located the lesion, the better the prognosis. However, all perforations have an inherently worsened prognosis.
Question 21
Endodontically treated posterior teeth are more susceptible to fracture than untreated posterior teeth. The best explanation for this is ____.
A
Moisture loss
B
Loss of root vitality
C
Plastic deformation of dentin
D
Destruction of the coronal architecture
Question 21 Explanation: 
D. Teeth that have been endodontically treated have lost much of their coronal dentin in the access formation, irrespective of the pre-endodontic caries state. This loss of dentin compromises the internal architecture of the tooth. Less Internal tooth structure, combined with the absorption of external forces (usually occlusal) may exceed the strength of dentin and result in fracture. Endodontic treatment and loss of pulp vitality are no longer thought to desiccate the tooth to the point of increasing risk of fracture.
Question 22
The primary reason for designing a surgical flap with a wide flap base is ____.
A
To avoid incising over a bony protuberance
B
To obtain maximum access to the surgical site
C
To maintain an adequate blood supply to the reflected tissue
D
To aid in complete reflection
Question 22 Explanation: 
C. The principles of flap design include the following: (1) flap design should ensure adequate blood supply and the base of the flap should be wider than the apex; (2) reflection of the flap should adequately expose the operative field; and (3) flap design should permit atrau¬matic closure of the wound.
Question 23
Pulp capping and pulpotomy can be more suc­cessful in newly erupted teeth than in adult teeth because ____.
A
A greater number of odontoblasts are present
B
Of incomplete development of nerve endings
C
An open apex allows for greater circulation
D
The root is shorter
Question 23 Explanation: 
C. In newly erupted teeth, the apical root end has not fully formed, allowing for greater blood supply to the tooth. Subsequent pulpal regeneration leads to greater long-term success.
Question 24
If a canal is ledged during instrumentation, the best way to handle the problem is to ____.
A
Continue instrumenting at the ledge. Although it may take some time, you will eventually bore your way to patency in the periodontal ligament space.
B
Immediately stop and fill to where the ledge begins.
C
Bind your irrigating needle in the canal and use short bursts of irrigant to loosen any debris blocking the canal. This will reopen the natural canal.
D
Prebend the tip of a small file, lubricate, and try to negotiate around the ledge.
E
Place citric acid or EDTA in the canal to soften the dentin. A small Gates Glidden or other rotary can be used to bypass the ledge.
Question 24 Explanation: 
D. Ledges can sometimes be bypassed; the canal coronal to the ledge must be sufficiently straight¬ened to allow a file to operate effectively. This may be achieved by anti curvature filing (file away from the curve). Precurve the file severely at the tip and use it to probe gently past the ledge. Otherwise, clean to the ledge and fill; warn the patient of poorer prognosis.
Question 25
Which of the following statements is not true regarding internal root resorption?
A
It happens rarely in permanent teeth.
B
It appears as an asymmetrical “moth-eaten” lesion in radiographs.
C
Chronic pulpal inflammation is the primary cause.
D
Prompt endodontic therapy will stop the process.
Question 25 Explanation: 
B. Internal resorption is most commonly identified during routine radiographic examination. Histologically, it appears with chronic pulpitis, including chronic inflammatory cells, multinucleated giant cells adjacent to granulation tissue, and necrotic pulp coronal to resorptive defect. Only prompt endodontic therapy will stop the process and prevent further tooth destruction.
Question 26
The 02 taper on hand K-files is .
A
0.2-mm increase in diameter per 1-mm increase in length
B
0.02-mm increase in diameter per 1-mm increase in length
C
0.2-mm increase in diameter per 2-mm increase in length
D
0.02-mm increase in diameter per 2-mm increase in length
Question 26 Explanation: 
B. 0.02-mm increase in diameter per 1-mm increase in length. Taper is the amount the file diameter increases each millimeter from the tip toward the handle. For a 0.02 taper file with 16- mm working surface, its diameter at the tip (D0) plus 0.32 mm (i.e., for a No. 8 file, it’s 0.08 + 16 x 0.02 = 0.40) should be equal to D16.
Question 27

Irreversible pulpitis pain in which of the following sites is most likely to radiate to the ear?

A
Maxillary premolar
B
Maxillary molar
C
Mandibular premolar
D
Mandibular molar
Question 27 Explanation: 
D, Mandibular molar. The perception of pain in one part of the body that is distant from the actual source of the pain is known as referred pain. Teeth may refer pain to other areas of the head and neck. Referred pain is usually provoked by stimulation of pulpal C-fibers, the slow- conducting nerves that, when stimulated, cause an intense, dull, slow pain. It always radiates to the ipsilateral side. Posterior teeth may refer pain to the opposite arch or periauricular area. Mandibular posterior teeth tend to transmit referred pain to the periauricular area more often than do the maxillary posterior teeth,
Question 28
A nasopalatine duct cyst is located between ____.
A
Two maxillary central incisors
B
Maxillary central and lateral incisors
C
Maxillary lateral and canine
D
Maxillary canine and first premolar
Question 28 Explanation: 
A. Nasopalatine duct cyst: a circular radiolucent area seen as a marked swelling in the region of the palatine papilla. It is situated mesial to the roots of the central incisors, at the site of the incisive fora¬men. The pulps of the anterior teeth test vital (whereas a periapical cyst tests nonvital). This is the most common type of maxillary developmental cyst. They often remain limited in size and are asymptomatic; they may become infected and show a tendency to grow extensively.
Question 29
An 8-year-old boy received a traumatic injury to a maxillary central incisor. One day later, the tooth failed to respond to electric and thermal vitality tests. This finding dictates ____.
A
Pulpectomy
B
Apexification
C
Calcium hydroxide pulpotomy
D
Delay for the purpose of re-evaluation
Question 29 Explanation: 

D. For decades, controversy has surrounded the validity of thermal and electric tests on trauma­tized teeth. Only generalized impressions may be gained from these tests subsequent to a traumatic injury. They are, in reality, sensitivity tests for nerve function and do not indicate the presence or absence of blood circulation within the pulp. It is assumed that subsequent to traumatic injury, the conduction capability of the nerve endings or sensory receptors is sufficiently deranged to inhibit the nerve impulse from an electric or ther­mal stimulus. This makes the traumatized tooth vulnerable to false negative readings from these tests.

Teeth that give a positive response at the initial examination cannot be assumed to be healthy or that they will continue to give a positive response over time. Teeth that yield a negative response or no response cannot be assumed to have necrotic pulps because they may give a positive response at later follow-up visits. It has been demonstrated that it may take as long as 9 months for normal blood flow to return to the coronal pulp of a trau­matized, fully formed tooth. As circulation is restored, responsiveness to pulp tests returns.

Question 30

Which of the following is the main side effect of bleaching an endodontically treated tooth?

A
External cervical resorption
B
Demineralization of tooth structure
C
Gingival inflammation
Question 30 Explanation: 
A. Internal bleaching alone causes 3.9% of external cervical root resorption (also referred to as peripheral inflammatory root resorption)] The presence of a barrier (base material) between the root filling material and the internal bleaching material should be ~4 mm to prevent this resorption.
Question 31

Which of the following can be viewed on a conventional radiograph?

A
Buccal curvature of roots
B
Gingival fibers
C
Calcification of canals
D
Periodontal ligament
Question 31 Explanation: 
C. Calcification of canals. Buccal curvature cannot be seen from the conventional radiographs. Gingival fibers and the periodontal ligament, being connective tissues, are radiolucent radiographically.
Question 32
There is a horizontal root fracture in the mid­dle third of the root of tooth 10 in an 11-year- old patient. The tooth is mobile and vital. How should this be treated?
A
Extract.
B
Pulpectomy immediately and splint.
C
Splint and observe.
D
Do nothing and follow-up in 10 to 14 days.
Question 32 Explanation: 
C. When a root fractures horizontally, the coronal segment is displaced to a varying degree, but generally the apical segment is not displaced. Because the apical pulpal circulation is not dis¬rupted, pulp necrosis in the apical segment is extremely rare. Pulp necrosis in the coronal seg¬ment results because of its displacement and occurs in only about 25% of cases. Because 75% do not lose vitality, emergency treatment involves repositioning the segments in as close proximity as possible and splinting the teeth for 2 to 4 weeks. After the splinting period is completed, follow-up is as with all dental traumatic injuries, at 3, 6, and 12 months and then yearly thereafter.
Question 33
Direct pulp cap is recommended for teeth with ____.
A
Carious exposures
B
Mechanical exposures
C
Calcification in the pulp chambers
D
Closed apices more than teeth with open apices
Question 33 Explanation: 

B. The indications for a direct pulp cap are (1) asymptomatic tooth; (2) with little or no hemorrhaging; (3) small (< 1 mm); and (4) welhisolated traumatic pulp exposure. It acts to stimulates the formation of a reparative dentin bridge over the exposure site and to preserve the underlying pulpal tissue. It is especially successful in immature teeth. Failure of direct pulp cap is indicated by (1) symptoms of pulpitis at any time; and (2) lack of vital pulp response after several weeks. Failures result in pulpal necrosis (continual pulpal insult), calcification of the pulp, or (rarely) internal resorption.

Direct pulp capping is primarily used on permanent teeth. (Not used often in primary teeth because the alkaline pH of calcium hydroxide.) It can irritate the pulp either mildly or (often) severely. With severe irritation, it increases the risk of internal resorption. With primary teeth, severe resorption is more common; in perma¬nent teeth, formation of reparative dentin occurs more often.

Question 34

Which one of the following cannot be observed on a conventional radiograph?

       

A
Canal calcification of tooth #15.
B
Buccal curvature of the mesial root of tooth #30.
C
Type of canals of tooth #21.
D
Open apex of tooth #8.
Question 34 Explanation: 
B. Buccal curvature of the mesial root of tooth #30. Radiographs provide a two-dimensional, mesial- distal view of a tooth. The buccal-lingual aspect of a tooth cannot be fully appreciated. Curvatures buccal or lingual are often not appreciated. Canal calcifications can be seen as relatively radiopaque obliterations of the pulp chamber and canal space. Tooth #21 is a mandibular premolar. The radiograph can give telling clues as to the anatomy, be it one or two canals. A canal that suddenly disappears midroot or appears off-center is often indicative of two canals. Open apices are often clearly visualized with radiographs.
Question 35
Which of the following is the most significant cause of ledge formation?
A
Infection
B
Remaining debris within the canal
C
No straight-line access
Question 35 Explanation: 
C. No straight-line access. After the orifice has been found, the clinician must decide if straight-line access has been achieved. Unnecessary deflection of the file can result in numerous consequences related to loss of instrument control. Attempts to clean and shape without straight-line access often lead to procedural errors such as ledging, transportation, and zipping.
Question 36
Which of the following teeth has the most consistent number of canal(s)?        

A
Mandibular incisor
B
Mandibular canine
C
Maxillary canine
D
Mandibular premolar
Question 36 Explanation: 
C. Maxillary canine. The percentage of one canal in maxillary canines has been found in some studies to be between 97% and 100%, making it one of the most consistent anatomical teeth in the mouth.
Question 37
Which of the following diagnostic criteria is least reliable in the assessment of the pulpal status of the primary dentition?
A
Swelling
B
Electric pulp test
C
Spontaneous pain
D
internal resorption
Question 37 Explanation: 
B, Electric pulp test. The relatively late appearance of A fibers in the pulp may help to explain why the electric pulp test tends to be unreliable in young teeth, since A fibers are more easily electrically stimulated than C fibers. Accuracy of pulp testing also depends on the patient’s ability to describe how the tooth reacts to stimuli. Clinicians must rely on experience, radiographs, clinical signs or symptoms, and their knowledge of the healing process to assess pulp vitality of young patients.
Question 38
Prolonged, unstimulated night pain suggests which of the following conditions of the pulp?
A
Pulpal necrosis
B
Mild hyperemia
C
Reversible pulpitis
D
Periodontal abscess
Question 38 Explanation: 
A. Lingering spontaneous pain is evidence of C-fiber stimulation. Even in degenerating pulps, C fibers may respond to stimulation. The excitability of C fibers is less affected by disruption of blood flow as compared with A fibers. C fibers are often able to function in hypoxic conditions (e.g., at the early stage of pulpal necrosis).
Question 39
Which of the following is the best radiographic technique to identify a suspected horizontal root fracture in a maxillary anterior central incisor?
A
Multiple Water’s projections
B
Multiple angulated periapical radiographs in addition to a normal, parallel-angulated, periapical radiograph
C
A panoramic radiograph
D
A reverse Towne’s projection
Question 39 Explanation: 
B. Radiographic examination for root fractures is extremely important. Because a root fracture is typically oblique (facial to palatal), one periapical radiograph may easily miss its presence, it is imperative to take at least three angled radi¬ographs (45, 90, 110 degrees) so that in at least one angulation the radiographic beam will pass directly through the fracture line and make it vis¬ible on the radiograph.
Question 40
Informed consent requires that the patient be advised of the following except for which one?
A
The benefits of endodontic treatment
B
The cost of endodontic treatment
C
The risks of endodontic treatment
Question 40 Explanation: 
B. Any notion of moral decision making assumes that rational agents are involved in making informed and voluntaiy decisions. In health care decisions, our respect for the autonomy of the patient would, in common parlance, mean that the patient has the capacity to act intentionally, with understanding, and without controlling influences that would mitigate against a free and voluntaiy act. It implies knowledge and understanding of the risks and benefits to treatment. This principle is the basis for the practice of “informed consent” in the physician-patient transaction regarding health care.
Question 41
Which of the following is the treatment of choice for a 7-year-old child with a nonvital tooth 30 with buccal sinus tract?
A
Gutta-percha filling
B
Gutta-percha filling followed by root-end surgery
C
Extraction
D
Apexogenesis
E
Apexification
Question 41 Explanation: 
E. If an immature tooth is nonvital, the diseased tissue must be removed via pulpectomy. Apexification is the treatment of choice.
Question 42
A patient complains of recent severe pain to percussion of a tooth. The most likely cause is ____.
A
Acute periradicular periodontitis
B
Chronic periradicular periodontitis
C
Reversible pulpitis
D
Irreversible pulpitis
Question 42 Explanation: 
A. Acute apical (periradicular) periodontitis (AAP): characterized by pain, commonly triggered by chewing or percussion. AAP alone is not indicative of irreversible pulpitis. It indicates that apical tissues are irritated, which may be associated with an otherwise vital pulp.
Question 43
Which of the following statements) is (are) true regarding treatment of a tooth presenting with a sinus tract?
A
Treat with conventional root canal therapy.
B
Antibiotics are not needed.
C
The sinus tract should heal in 2 to 4 weeks after conventional root canal therapy.
D
If the tract persists post-root canal therapy, do root-end surgery with root-end filling.
E
All of the above choices are true.
Question 43 Explanation: 
All of the choices are true. Suppurative apical periodontitis: continuously or intermittently draining sinus tract, usually drains into the oral mucosa. The exudate can also drain through the gingival sulcus of the involved tooth, mimicking a periodontal lesion with a “pocket.” However, this is not a true periodontal pocket because there is not a complete detachment of connective tissue from the root surface. It should be treated with conventional root canal therapy. Antibiotics are not needed, since the infection is localized and draining. If the tract does not heal within a few weeks, root-end surgery may be required. If left untreated, however, it may become covered with an epithelial lining and become a true periodontal pocket.
Question 44

The major objectives of access preparation include all of the following except which one?

A
The attainment of direct, straight-line access to canal orifices.
B
The confirmation of clinical diagnosis.
C
The conservation of tooth structure.
D
The attainment of direct, straight-line access to the apical portion of the root.
Question 44 Explanation: 
B. The confirmation of clinical diagnosis. Confirmation of clinical diagnosis should be made before treatment is rendered. Access is the first and arguably the most important phase of nonsurgical root canal therapy. The objectives are: (1) to achieve straight-line access to the apical foramen or curvature of the canal, (2) to locate all root canal orifices, and (3) to conserve sound tooth structure.
Question 45
Which is the most likely to cause pulp necrosis?          
A
Subluxation
B
Extrusion
C
Avulsion
D
Concussion
Question 45 Explanation: 
C. Avulsion. To have pulp space infection, the pulp must first become necrotic. This will occur in a fairly serious injury in which displacement of the tooth results in severing of the apical blood vessels.
Question 46
While performing nonsurgical endodontic therapy you detect a ledge. What should you do?
A
Use a smaller instrument and get by the ledge.
B
Fill as far as you have reamed.
C
Use a small, round bur and remove the ¡edge.
D
Continue working gently with larger files to remove the ledge.
Question 46 Explanation: 
A. Use a smaller instrument and get by the ledge. Ledges can sometimes be bypassed; the canal coronal to the ledge must be sufficiently straightened to allow a file to operate effectively. This may be achieved by anticurvature filing (file away from the curve). Precurve the file severely at the tip and use it to probe gently past the ledge. Otherwise, clean to the ledge and fill it, but you must warn the patient of a poorer prognosis.
Question 47

What is the safest recommended intracoronal bleaching chemical?

A
Hydrogen peroxide
B
Sodium perborate
C
Sodium hypochlorite
D
Carbamide peroxide
Question 47 Explanation: 
B. Sodium perborate is more easily controlled and safer than concentrated hydrogen peroxide solutions. Therefore, it should be the material of choice for internal bleaching.
Question 48
Twisting a triangular wire best describes the manufacturing process of a ____.
A
Reamer
B
Barbed broach
C
Hedstrom file
D
K-Flex file
Question 48 Explanation: 
A. The K-file and K-reamer are the oldest instruments for cutting and machining dentin. They have been made from a steel wire that is ground to a tapered square or triangular cross section and then twisted to create either a file or a reamer. A file has more flutes per unit length than does a reamer. The K-Flex™ file is a modification of the shape of the K-file, with a noncutting tip design.
Question 49

At what stage is endodontic treatment considered complete?

A
When a temporary restoration is placed and the rubber dam removed.
B
When canals are seared off and plugged.
C
When the coronal restoration is completed.
D
When the patient is asymptomatic.
Question 49 Explanation: 
C. When the coronal restoration is completed. After root canal therapy, the canals inside the roots have been cleaned and permanently sealed. However, there is a temporary filling in the outer surface of the tooth. The patient must be told that they need a permanent filling or crown for the tooth. This is very important for the protection of the tooth against fracture or reinfection of the root canal.
Question 50
Severity of the course of a periradicular infec­tion depends upon the ____.
A
Resistance of the host
B
Virulence of the organisms
C
Number of organisms present
D
Both A and B only
E
All of the choices are true
Question 50 Explanation: 
E. A patient’s immune response to a periradicular infection varies according to the person. The size and volume of the pulp, the number and quality of the nerves, and the pulpal vascularity and cel- lularity are all unique to the person. The different virulence of organisms causing the infection may cause differences in pain experienced, differ¬ences in the amount of orthoclastic activity, etc. Sheer numbers of organisms can influence their virulence.
Question 51
Which of the following statements best describes pulpal A-delta fibers when compared to C fibers?
A
Larger unmyelinated nerve fibers with slower conduction velocities
B
Larger myelinated nerve fibers with faster conduction velocities
C
Smaller myelinated nerve fibers with slower conduction velocities
D
Smaller unmyelinated nerve fibers with faster conduction velocities
Question 51 Explanation: 
B. The pulp contains two types of sensory nerve fibers: myelinated (A fibers) and unmyelinated (C fibers). A fibers include A-beta and A-delta, of which A-delta is the majority. A-delta fibers are principally located in the region of the pulp- dentin junction, have a sharp pain associated with them, and respond to relatively low thres¬hold stimuli. C fibers are probably distributed throughout the pulp, are associated with a throb¬bing pain sensation, and respond to relatively high threshold stimuli.
Question 52

How should a vital second permanent molar with a 2.0-mm exposure on a 12-year-old patient be treated?

         

A
Apexification
B
Direct pulp capping
C
Indirect pulp capping
D
Extract
E
Apexogenesis
Question 52 Explanation: 
A. Apexification. Induces further root development in a pulpless tooth; stimulates the formation of a hard substance at the apex so as to allow obturation of the root canal space. 2.0-mm pulp exposure is too big to perform vital pulp therapy. Pulpotomy should not be performed on permanent teeth (unless apexogenesis) because it causes calcification of the root canal system.
Question 53
During a routine 6-month endodontic treatment recall evaluation, you note a marked decrease in the radiographic size of the periradicular radiolucency. Which of the following is the most appropriate treatment plan?
A
Extraction.
B
Nonsurgical endodontic retreatment.
C
Recall the patient in another 6 months.
D
Surgical endodontic retreatment.
Question 53 Explanation: 
C. When endodontic treatment is done properly, healing of the periapical lesion usually occurs with osseous regeneration, which is characterized by gradual reduction and resolution of the radiolucency on follow-up radiographs. The rate of bone formation is slow, and complete resolution may take longer than the standard 6-month follow- up, especially with elderly patients. As long as the radiolucency appears to be resolving as opposed to enlarging, an extended re-evaluation is in order.
Question 54
Which of the following statements regarding post preparation is incorrect?
A
The primary purpose of the post is to retain a core in a tooth with extensive loss of coronal structure.
B
The need for a post is dictated by the amount of remaining coronal tooth structure.
C
Posts reinforce the tooth and help to prevent vertical fractures.
D
At least 4 to 5 mm of remaining gutta-percha after post space preparation is recommended.
Question 54 Explanation: 
C. The most important part of the restored tooth is the tooth itself. No combination of restorative materials can substitute for tooth structure. Posts do not reinforce the tooth but, rather, further weaken it by additional removal of dentin and by creating stress that predisposes to root fracture.
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