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study form to the students, to eliminate any chance of biasing responses toward endodontic retreatment.

The following directions and scenario were given to

all students: Directions. Read the following scenario and select

either option 1 or option 2.Please do not discuss this with your fellow students.Base your decision only on the information given.

There is no right or wrong answer.Scenario. Which of the 2 treatment options below

would you prefer in your mouth to take care of thischronically sore tooth which recently caused an episodeof acute swelling and pain? The tooth in question istooth #21; it has already had root canal treatment.

A radiographic image, Fig. 1 , was embedded in the

study form. Although each student received this samescenario, one half of the students received treatmentoption descriptions biased toward endodontic retreat-ment selection and the other half option descriptionsbiased toward extraction and implant selection.

Options biased to endodontic retreatment selection-Option 1 You can have the tooth removed, wait 3months for the extraction site to heal, and then have ametal implant placed surgically into the jaw bone. Acrown can then be anchored to your implant once theimplant has successfully fused with the bone. You canwear a temporary partial denture with a fake acrylic

tooth, something similar to wearing an orthodonticretainer, to hide the spot with the missing tooth whilethe bone heals. The total treatment would take between4 and 6 visits. Option 2 You can predictably keep your natural tooth by having the root canal treatment re-done. You would not have to have surgery and the toothwould feel more like your other natural teeth. Thetreatment would take between 1 and 2 visits. In theunlikely event that the retreatment is not successful, youcould then have the tooth extracted and have an im- plant placed.

Options biased to extraction and implant placement selection-Option 1 You can have the previous root ca-nal treatment redone with a 75% chance of healinglong term. You have a 25% chance that it won’t heal. If the root canal–associated disease heals, there is still arisk of tooth loss. The tooth is still susceptible to re-current decay, periodontal disease, or possible root fracture, any of which could result in the need for extraction in the future. Option 2 You can have thetooth extracted now and have it replaced with an im- plant. The chance of successful treatment with an im- plant and crown replacement is approximately 95%.

The discomfort associated with the natural tooth will be permanently eliminated. The implant and its crown willnever decay, and if there is any periodontal disease in your mouth, the implant will be affected much less than your own teeth. Statistical analysis was performed withchi-squared test. Level of signicance was established at P .05.

RESULTSThe results are presented in Table I . Fifty-three stu-

dents were present for the study, including 19 femalestudents, 2 students of Asian descent, 6 students of

African descent, and 1 student of Hispanic descent. Oneunidentied student chose not to participate after read-ing the consent form and the study form with scenario.There was a signicant difference between the 2 biasgroups ( P .0006). The majority of students in the biasto retreatment group selected the retreatment option.The majority of students in the bias to extraction andimplant group selected the implant option.

DISCUSSIONThe results of the study showed that a biased pre-

sentation describing 2 reasonable treatment options for

Fig. 1. Radiogram of tooth #21.

Table I. Selection option resultsGroup Retreatment Implant

Bias to retreatment 17 10Bias to implant 4 21

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failed endodontic therapy can inuence the option se-lected by a patient. The predoctoral students were se-lected because of their perceived ability to read andunderstand the scenario and treatment choices withoutfurther explanation. These students had as yet had nocourses in restorative dentistry, prosthododontics, peri-

odontics, endodontics, oral pathology, or oral surgery.With their limited exposure to the dental school curric-ulum, it was unlikely that they had developed anyopinions regarding the merit of one treatment optionover another and would base their selection on theinformation given. Participants were not asked whetherthey had a personal dental history or family dentalhistory of previous endodontic or implant therapywhich could have inuenced their decision dependingon whether there had been a favorable or unfavorableoutcome.

The descriptions of the treatment options were pur-

posefully kept short; each was 4 sentences in length.The endodontic retreatment option–biased pair wasintended to be inuenced by the qualitative descriptionsof the procedures in terms of number of appointments,time to completion, and the need for surgical procedurewith implant placement. The implant option–biasedpair was intended to be inuenced primarily on thebasis of prognosis. The prognosis estimate of 75%chance of healing with nonsurgical retreatment is areasonable estimate to present to patients based onrecent success-failure studies on endodontic nonsurgi-cal retreatment of cases with periapical (PA) le-

sions.9-11

The prognosis estimate of 95% chance of success with single tooth impl ant is also a reasonableestimate to present to patients. 12-14

Other treatment options for the study scenario couldhave been included in the study. Treatment options forendodontically treated teeth with asymptomatic PA le-sions could include no treatment with follow-up, non-surgical retreatment, surgical retreatment, or a combi-nation of nonsurgical and surgical retreatment. Thescenario in the study described ongoing symptoms witha recent acute episode of pain and infection. Althoughno treatment is favored by general dentists more often

than by endodontists for asymptomatic te eth with PAlesions after initial endodontic treatment, 5,6 the sce-nario was meant to exclude the option of no treatment.Surgical endodontic treatment could have been listed asan alternative third option with an approximate equiv-alent prognosis to nonsurgical retreatment 3,15 or a bet-ter prognosis than nonsurgical retreatment. 16 However,we wanted the participants to consider only 1 surgicaloption, that of extraction and implant placement. With#21 in the esthetic zone, virtually all patients wouldprefer to have the tooth replaced if the tooth wereextracted. This particular case, with #20 serving as an

abutment for a xed partial denture and #22 beingcaries and restoration free, was intended to exclude axed partial denture replacement option.

We chose not to include cost comparisons in thetreatment option descriptions. We wanted to primarilyassess the results based on presentation bias in progno-

sis and procedural description. If cost estimates wereincluded, the results would likely be skewed more tothe lower-cost option, particularly due to the assumednancial constraints of the study population of rst-year dental students. Students at the University of Ken-tucky College of Dentistry are required to pay standardpatient fees for all treatment rendered; there are nostudent fee discounts or waivers. In the study scenario,the tooth may have only needed an access restorationfor the apparently serviceable crown after retreatment,which would be much less expensive than the extrac-tion and implant option. Even if the crown needed to be

replaced, a cost-benet analysis study found that ortho-grade endodontic treatment, crown lengthening, andcrown was less expensiv e than the cost of implantplacement and restoration. 17 Alternatively, implant ad-vocates now state that the cost of extraction and implantreplacement for single teeth compares favorably, andmay be more advantageous over the long ter m com-pared with endodontic and restorative therapy. 18

Standard considerations for implant placement notdescribed in the treatment options include surgicalcomplications, such as neurosensory disturbance andthe possible need for site enhancement with bone graft-

ing, and mechanical complications, such as prosthesisand implant fracture. 19

Patients desire varying levels of auton omy whenmaking decisions regarding their treatment. 8 Whetherpatients desire a passive, collaborative, or active roleregarding their treatment, they will all rely to a certainextent on the information provided by their dentist fordecision making. The patient’s dentist must objectivelyand ethically provide information to the patient regard-ing treatment options, treatment considerations, risksand benets of the different options, and the expectedprognosis of the different options. The present studyshows that if treatment options are presented in a biasedmanner toward one option, the patient is more likely toselect that treatment option.

REFERENCES1. Friedman S, Stabholz A. Endodontic retreatment—case selection

and technique. Part 1: Criteria for case selection. J Endod1986;12:28-33.

2. Allen RK, Newton CW, Brown CE. A statistical analysis of surgical and nonsurgical retreatment cases. J Endod 1989;15:261-6.

3. Kvist T, Reit C. Results of endodontic retreatment: a randomizedclinical study comparing surgical and nonsurgical procedures. JEndod 1999;25:814-7.

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4. McCaul LK, McHugh S, Saunders WP. The inuence of spe-cialty training and experience on decision making in endodonticdiagnosis and treatment planning. Int Endod J 2001;34:594-606.

5. Balto HAG, Ebtissam MAM. A comparison of retreatment de-cisions among general dental practitioners and endodontists. JDent Educ 2004;68:872-9.

6. Pagonis TC, Cheng DF, Hasselgren G. Retreatment decisions—a

comparison between general practitioners and endodontic post-graduates. J Endod 2000;26:240-1.7. Di Fiore PM, Tam L, Thai HT, Hittleman E, Norman RG.

Retention of teeth versus extraction and implant placement:treatment preferences of dental faculty and dental students. JDent Educ 2008 Mar; 72:352-8.

8. Chapple H, Shah S, Caress A, Kay EJ. Exploring dental patients’preferred roles in treatment decision-making—a novel approach.Br Dent J 2003;194:321-7.

9. Gorni FGM, Gagliani MM. The outcome of endodontic retreat-ment: a 2-yr follow-up. J Endod 2004;30:1-4.

10. Chevigny C, Dao TT, Basrani BR, Marquis V, Farzaneh M,Abitol S, Friedman S. Treatment outcome in endodontics: theToronto study—phases 3 and 4: orthograde retreatment. J Endod2008;34:131-7.

11. Sundqvist G, Figdor D, Persson S, Sjogren U. Microbial analysisof teeth with failed endodontic treatment and the outcome of conservative re-treatment. Oral Surg Oral Med Oral Pathol OralRadio Endod 1998;85:86-93.

12. Lindhe T, Gunne J Tillberg A, Molin M. A meta-analysis of implants in partial edentulism. Clin Oral Implants Res 1998;9:80-90.

13. Eckert SE, Choi YG, Sanchez AR, Koka S. Comparison of dental

implant systems: quality of clinical evidence and prediction of 5-yr survival. Int J Oral Maxillofac Implants 2005;20 406-415.

14. Thomas MV, Beagle JR. Evidence-based decision-making: im-plants versus natural teeth. Dent Clin North Am 2006;50:451-461.

15. Wang N, Knight K, Dao T, Friedman S. Treatment outcome inendodontics: the Toronto study. Phases I and II: apical surgery.

J Endod 2004;30:751-61.16. Rubinstein RA, Kim S. Long-term follow-up of cases consideredhealed one year after apical microsurgery. J Endod 2002;28:378-463.

17. Moiseiwitsch JRD, Caplan D. A cost-benet comparison be-tween single tooth implant and endodontics. J Endod 2001;27:235.

18. Ruskin JD, Morton D, Karayazgan B, Amir J. Failed root canals:the case for extraction and immediate implant placement. J OralMaxillofac Surg 2005;63:829-31.

19. Torabinejad M, Goodacre CJ. Endodontic or dental implanttherapy. J Am Dent Assoc 2006;137:937-77.

Reprint requests:

Keith H. Foster, DMDAssistant ProfessorDivision of EndodonticsUniversity of Kentucky College of DentistryChandler Medical CenterD-444 Dental Science BuildingLexington, KY 40536-0297kfost2@uky.edu

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