1. What is the current thinking on use1. What is the current thinking on useof the rubber dam?of the rubber dam?The dam is an absolute necessity for treatment. Itensures a surgically clean operating field that reduceschance of cross-contamination of the root canal,retracts tissues, improves visibility, and improvesefficiency. It protects the patient from aspirationof files, debris, irrigating solutions, and medicaments.From a medicolegal standpoint, use of the dam isconsidered the standard of care.
2. What basic principles should be kept in2. What basic principles should be kept inmind for proper access opening?mind for proper access opening?The root canal system is usually a multicanaledconfiguration with fins, loops, and accessory foramina.When possible, the opening must be of sufficient size,position, and shape to allow straight-line access intothe canals. Access of inadequate size and position invitesinadequate removal of caries,com promises proper instrumentation, and inhibitsproper obturation. However, overzealous access leads toperforation, weakening of tooth structure, and potentialfracture.
3.What are the current concepts on irrigating3.What are the current concepts on irrigatingsolutions in endodontics?solutions in endodontics?The type of irrigant is of minor importance in relationto the volume and frequency. The crucial factor isconstant irrigation to remove dentinal debris, toprevent blockage, and to lessen the chance of apicalintroduction of debris. Several studies have shown theefficacy of saline, distilled water, sodium hypochlorite,hydrogen peroxide, combinations of the above, andmany other agents. The results show no advantage tochemomechanical preparation of the root canalsystem.
4. Of what material are endodontic files4. Of what material are endodontic filescurrently made?currently made?Hand-operated instruments, includingbroaches, H-files, K-files, reamers, K- flexfiles, and S-files, are made of stainlesssteel as opposed to carbon steel, whichwas used in the past. Stainless steelbends more easily, is not as brittle, is lesslikely to break compared with carbonsteel, and can be autoclaved withoutdulling. In addition, hand and rotary filesare now being made of nickel-titanium.
5. What are the characteristics of a5. What are the characteristics of aK-file?K-file?The K-file is made by machine grinding of stainless steel wireinto a square shape (some companies produce a triangularshape). The square wire is then twisted by machines in acounterclockwise direction to produce a tightly spiraled file.
6. What are the characteristics of a6. What are the characteristics of areamer?reamer?The reamer is made by machine twisting of atriangular stainless steel stock wire in acounterclockwise direction but into a less tightlyspiraled instrument than the K-file.
7. How does the K-flex file7. How does the K-flex filediffer?differ?The K-flex file is produced from a rhomboid or adiamond-shaped stainless steel stock wiretwisted to produce a file. However, the two acuteangles of the rhombus producea cutting edge of increased sharpness andcutting efficiency.The low flutes made from the obtuse anglesform an area for debris removal.
8. How does filing differ from8. How does filing differ fromreaming?reaming?Filing establishes its cutting action uponwithdrawal of the instrument. The instrument isremoved from the canal without turning. Thus ituses basically a push-pull motion. Reaming isdone by placing the instrument in thecanal, rotating, and withdrawing.
9.Why is nickel-titanium becoming a material of9.Why is nickel-titanium becoming a material ofchoice for endodontic hand and rotarychoice for endodontic hand and rotaryinstruments?instruments?The newer hand and rotaiy instruments made fromnickel-titanium have excellent flexibility andstrength after repeated sterilization,are quiteanticorrosive, and resist fracture quite well.
10.What types of hand-operated10.What types of hand-operatedimplements for root canal instrumentationimplements for root canal instrumentationare currently available?are currently available?K-type files and reamers are still widely usedbecause of their strength and flexibility. H-typeHedstrom files are quite popular because of theiraggressive ability to cut dentin. S-files are highlyefficient for cutting dentin on the withdrawal strokeand for filing and reaming. Flex-it files are a newmodification with a non cutting tip design. Thisdesign allows guidance of the tip through curvaturesand reduces the risk of ledging, perforation, andtransportation of the apex.
11. What is the current status on11. What is the current status onacceptability of root canal obturationacceptability of root canal obturationmaterials?materials?Gutta percha remains the most popular and acceptedfilling material for root canals. Numerous studies havedemonstrated that it is the least tissue-irritatingand most biocompatible material available. Althoughdifferences occur among manufacturers,gutta percha contains transpolyisoprene, bariumsulfate, and zinc oxide, which provide an inert,compactible, dimensionally stable material that canadapt to the root canal walls.
N-2 pastes and other paraformaldehyde-N-2 pastes and other paraformaldehyde-containing pastes are not approved by thecontaining pastes are not approved by the(FDA).Several studies have shown conclusively(FDA).Several studies have shown conclusivelythat such root-filling pastes are highly cytotoxicthat such root-filling pastes are highly cytotoxicin tissue culture;reactions to bone include chronicin tissue culture;reactions to bone include chronicinflammation, necrosis, and bone sequestration.inflammation, necrosis, and bone sequestration.Compared with gutta percha, the pastes areCompared with gutta percha, the pastes arehighly antigenic and perpetuate inflammatoryhighly antigenic and perpetuate inflammatorylesions. For these reasons they are notlesions. For these reasons they are notconsidered the standard of endodontic care.considered the standard of endodontic care.
12. What is the proper apical extension of a12. What is the proper apical extension of aroot canal filling?root canal filling?In the past recommendations were made to fill aroot canal to the radiographic apex in teeth thatexhibited necrosis or areas of periapicalbreakdown and to stop slightly short of this pointin vital teeth. Currently, however, it is generallyrecommended that a root canal be filled to thedentinocementum junction, which is 0.5-2 mmfrom the radiographic apex. Filling to theradiographic apex is usually overfilling oroverextending and increases the chance of chronicirritation of periapical tissues.
13. Describe the crown-down pressureless13. Describe the crown-down pressurelesstechnique of root canal instrumentation.technique of root canal instrumentation.With the crown-down pressureless technique the canal isprepared in a coronal toapical direction by initiallyinstrumenting the coronal two-thirds of the canal beforeany apical preparation. This technique, popularized byMarshall-Pappin, minimizes apically extruded debris andeliminates binding of instruments coronally, therebymaking apical preparation more difficult.
14. What is the balanced-force concept of14. What is the balanced-force concept ofroot canal instrumentationand reparation?root canal instrumentationand reparation?It is based on the idea of balancing the cutting forcesover a greater area of the canal and focusing less forceon the area where the file tip engages the dentin.The technique is done with the Flex-it file with a noncutting tip and a triangular cross- section. By using thistype of file in a counterclockwise reaming motion, ledgingisminimized, more inner canal curvature is accomplished,and less zipping of the apex occurs.
15. What is the frequency of fourth canals in15. What is the frequency of fourth canals inmesial roots of maxillary first molars?mesial roots of maxillary first molars?In an extensive study of maxillary first molars, 51% ofthe mesiobuccal roots contained either a larger buccaland smaller lingual canal or two separate canals andforamina. This finding shows the importance of searchingfor a fourth canal to ensure clinical success.
16. Are electronic measuring devices for root16. Are electronic measuring devices for rootcanal of any clinical value in everydaycanal of any clinical value in everydayendodontic practice?endodontic practice?Yes. Electronic measuring devices have been shown byseveral investigators to be quite accurate. In general,they work by measuring gradients in electrical resistancewhen a file passes from dentin (insulator) to conductiveapical tissues.They are quite useful when the apex isobscured on a radiograph by sinus superimposition, otherroots, or osseous structures.
17. What is the current thinking on the17. What is the current thinking on theuse of medicaments in endodontic practice?use of medicaments in endodontic practice?Formerly, medicaments were in wide use in endodonticsto kill bacteria inthe canal. However, current thinking stresses thoroughdebridement of canals and the use of irrigating solutionsto clean canals. Medicaments are not stressed, becauseall have been shown to be cytotoxic in tissue culture. Inaddition, several medicaments have been shown to elicitimmunologic reactions in animal studies. Mechanicalcanal cleaning sufficiently lowers microbial levels to allowthe local defense mechanisms to heal endodonticperiapical lesions.
18. Discuss the variations of postoperative18. Discuss the variations of postoperativepain in one-visit vs. two- visit endodonticpain in one-visit vs. two- visit endodonticprocedures.procedures.Several studies show no difference in postoperative painin one-visit vs. two-visit endodontic procedures. In fact,one study found that single-visit therapy resulted inpostoperative pain approximately one-half as often asmultiple-visit therapy.
19. What is the role of sealer-cements in19. What is the role of sealer-cements inroot canal obturation?root canal obturation?Sealer-cements are still widely recommended for usewith a semisolid obturating material (gutta percha). Thesealers fill discrepancies between the root filling and canalwall, act as a lubricant, help to seat cones of guttapercha,and fill accessory canals and/or foramina apically.
20.Apatient presents with an extremely painful20.Apatient presents with an extremely painfullowerlower molar requiring endodontic therapy. Youmolar requiring endodontic therapy. Youhave already used six cartridges of lidocainehave already used six cartridges of lidocainewith epinephrine to achieve anesthesia. Thewith epinephrine to achieve anesthesia. Thepatient begins to react differently. In brief, whatpatient begins to react differently. In brief, whatare the signs of local anesthetic toxicity?are the signs of local anesthetic toxicity?Local anesthetic toxicity depends on the blood level andthe patients status. In general, a mild toxic reactionmanifests as agitation, talkativeness, and increasedvital parameters (blood pressure, heart rate, andrespiration). A massive reaction manifests as seizures,generalized collapse of the central nervous system, andpossible myocardial depression and vasodilation.
21. What is the reason for attempting to21. What is the reason for attempting toanesthetize the mylohyoid nerve foranesthetize the mylohyoid nerve forendodontic treatment of a symptomaticendodontic treatment of a symptomaticlower first molar?lower first molar?The mylohyoid nerve has been shown to supply sensoryinnervation to mandibular molars, especially the mesialroot of first molars. Infiltration of this nerve as it coursesalong the medial surface of the mandible is often helpful.
22. What is the physiologic basis of the22. What is the physiologic basis of thedifficulty in achieving proper pulpaldifficulty in achieving proper pulpalanesthesia in the presence of inflammationanesthesia in the presence of inflammationor infection?or infection?Attaining effective pulpal anesthesia in the presenceof pulpal-alveolar infection or inflammation is bften quitedifficult because of changes in tissue pH.The normaltissue pH of 7.4 decreases to 4.5—5.5. This change in pHdue to pulpal-periapical pathology favors a shift to acationic form of the local anesthesia molecule, whichcannot diffuse through the lipoprotein neural sheath.Therefore, anesthesia is ineffective.
23. The quinolone class of antibiotics, which includes23. The quinolone class of antibiotics, which includesciprofloxacin,are becoming quite popular. Do theyciprofloxacin,are becoming quite popular. Do theyhave any role in infections?treating alveolarhave any role in infections?treating alveolarVery little,if any.Most anaerobes implicated in endodontic-alveolar abscesses are resistant to the quinolones.
24. What efficacy do the cephalosporins have in24. What efficacy do the cephalosporins have intreating acute pulpal- periapical infections?treating acute pulpal- periapical infections?Although the cephalosporins are broad-spectrum antibiotics,their activity is limited in pulpal-periapical infections, whichare mixed infections predominantly due to obligateanaerobic bacteria. The cephalosporins are not highlyeffective against such bacteria and actually have less activityagainst many anaerobes than penicillin. For seriousinfections that are penicillin or erythromycin-resistant,clindamycin is much more effective because of its activityagainst the obligate and facultative organisms in pulpal-periapical infections.
25. For years it was taught that any bacteria25. For years it was taught that any bacterialeft behind in an obturated canal would dieleft behind in an obturated canal would dieand therefore cause no problems. What areand therefore cause no problems. What arethe latest findings about this controversy?the latest findings about this controversy?The most recent electron micrograph studies have shownpersistence of bacteria in the apical portion of roots intherapy-resistant lesions. The result is persistentperiapical pathosis.
26. A patient presents with swelling, in obvious26. A patient presents with swelling, in obviousneed of endodontic therapy. His medical historyneed of endodontic therapy. His medical historyis significant for penicillin allergy and asthma,is significant for penicillin allergy and asthma,for which he is taking Theo-Dur. Whatfor which he is taking Theo-Dur. Whatprecautions should you exercise?precautions should you exercise?By no means should erythromycin be used as analternative to penicillin. Theo-Dur is a form of heophyllineused for chronic reversible bronchospasmassociated withbronchial asthma, and erythromycin has been shown toelevate significantly serum levels of theophylline.
27. What precautions should be taken in27. What precautions should be taken inprescribing antibiotics to a female patientprescribing antibiotics to a female patientwho takes birth control pills?who takes birth control pills?The dentist should warn the patient that oral antibiotics maydecrease the effectiveness of birth control pills and that theymay be ineffective during the course of antibiotic therapy.The most often implicated antibiotic is the penicillin class,although erythromycin, cephalosporin, tetracyclines, andmetronidazole also have been implicated.
28. What roles do nonsteroidal antiinflammatory28. What roles do nonsteroidal antiinflammatorydrugs (NSAIDs) have in endodontic practice?drugs (NSAIDs) have in endodontic practice?NSAIDs have a significant role in endodontic practice. Manypatients require postoperative medication to controlpericementitis, which can be quite painful after pulpectomyand may persist for several days.The NSAIDs arequiteeffective; their mechanism of action is to inhibitsynthesis of prostaglandins. One study showed thatibuprofen, when given preoperatively to symptomatic andasymptomatic patients, significantly reduces postoperativepericementitis.
29. What is the current status of29. What is the current status ofculturing and sensitivity testingculturing and sensitivity testingforendodontic.periapical infections?forendodontic.periapical infections?According to current thinking, if the proper clinicalguidelines are followed, including use of rubber dam,proper chemomechanical cleaning of the root canalsystem, and proper use of correct antibiotics asindicated, culturing and sensitivity testing are notrequired. Proper culturing for both facultative andanaerobic bacteria is expensive,time-consuming, and notcost-effective, given the high success rate of properlydone endodontic therapy.
30. The role of gram-negative anaerobic bacteria is30. The role of gram-negative anaerobic bacteria isan established fact in the pathogenesis of endodontican established fact in the pathogenesis of endodonticlesions. What role does the bacterial endotoxin play?lesions. What role does the bacterial endotoxin play?Endotoxins are highly potent lipopolysaccharidesreleased from the cell walls of gram-negativebacteria. They are able to resorb bone viastimulation of osteoclastic activity, activation ofcomplement cascades, and stimulation oflymphocytes and macrophages. Various studieshave demonstrated their presence in pulplessteeth (with necrotic tissue) and apical lesions.
31. What antibiotics are considered most31. What antibiotics are considered mosteffective in treatment of orofacial infectionseffective in treatment of orofacial infectionsof endodontic origin that do not respond toof endodontic origin that do not respond tothe penicillins?the penicillins?clindamycin is the drug of choice. It produces highbone levels and is highly effective against anaerobicbacteria, but it must be used with caution because of thepotential for pseudomembranous colitis. A second choice ismetronidazole, which also is quite effective against gram-negative obligate anaerobes.
32. What is considered the antibiotic of32. What is considered the antibiotic ofchoice in treatment of orofacial infections ofchoice in treatment of orofacial infections ofendodontic origin?endodontic origin?Penicillin is highly effective against most of the obligateanaerobes in endodontic infections, and because theinfections are of a mixed nature with strict substrateinterrelationships among various bacteria, the death ofseveral strains has a profound effect on the overallpopulation of an endodontic- periapical infection.
33.What types of bacteria are predominant33.What types of bacteria are predominantpathogensin endodontic-periapical infections?pathogensin endodontic-periapical infections?Many well-done studies have shown definitively thepredominant role of gram-negative obligate anaerobicbacteria in endodontic-periapicalinfections.Earlierstudiesgenerallyimplicatedfacultativeorganisms(streptococci,enterococci,lactobacilli),butimprovedculturingtechniquesestablishedthepredominance of obligate anaerobes. A recent study furtherdemonstrated theimportant role of Porphyromonas endodontalis(formerly Bacteroides endodontalis) in endodontic infections.