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Quality of obturation in student cases instructed by endodontic versus general dentistry faculty
JOURNAL OF ENDODONTICS Copyright © 1999 by The American Association of Endodontists
Printed in U.S.A. VOL. 25, No. 6, JUNE 1999
Quality of Obturation in Student Cases Instructed by Endodontic Versus General Dentistry Faculty Robert B. Mayhew, DMD, PhD, Timothy A. Svec, DDS, MS, Craig W. Johnson, PhD, and Scott R. Makins, DDS
Endodontic literature suggests that only about 60% of endodontic therapy meets current technical standards and that general dentists may be making a significant contribution to this compromised care. If so, where in the continuum of dental education does this begin. This study evaluated the quality of obturation in mandibular molars provided on the one hand by 3rd year dental students instructed by endodontic faculty, and on the other hand by 4th year students instructed by general dentistry faculty, versus the quality of obturation achieved by endodontic residents who served as a control for both groups. Final radiographs were chosen from students in all three groups so that there were 22 samples per group. Three evaluators rank-ordered the radiographs. In order of excellence, the results were: (a) residents, (b) 3rd year students, and (c) 4th year students. There was no significant difference between the 3rd year students or the residents, only between residents and 4th year students (p < 0.05). The reasons for this outcome may range from dental school objectives to the private practice procedures of the general dentists who instructed the 4th year students.
the radiographic apex to a significantly greater degree than undergraduate students or an endodontist. Clinical application of endodontic techniques for undergraduate dental students is usually concentrated in the 3rd and 4th years of the dental curriculum within American Association of Dental Schools member institutions. Most 3rd year students are monitored and instructed by endodontic faculty. The 4th year endodontic experience may be monitored by faculty with various levels of expertise, from general practitioners only to endodontic specialists only. Simulation of the private practice situation, in which only the more difficult cases are referred to specialists, is the general premise for using only general dentistry faculty in the 4th year. If, globally, 60% of endodontic obturations are not technically satisfactory, and if general dentists may be making a significant contribution to this compromised care, where in the continuum of dental education is a compromised standard accepted, if at all? In an effort to address this question at art early phase of the continuum, this study compared the quality of obturation in mandibular molars treated by 3rd year dental students who were instructed by endodontic faculty to obturations performed by I st year endodontic residents serving as a control standard. The quality of obturation provided by 4th year students instructed by the general dentistry faculty was then also compared with the same endodontic resident case serving as a control.
METHODS Final radiographs were chosen randomly from one case of mandibular molars per student from students ranked in the top 50% of both the 3rd and 4th year classes for the academic year 19941995 at this institution. In addition, 2 cases from each of I1 endodontic residents enrolled between 1990 and 1995 were selected; these were the first two mandibular molars that each resident treated. This group was treated as the control group in the statistical evaluation of the results. For the evaluation, there were 22 cases from each of the three groups. Only one view of each completed case of a mandibular 1st oi 2nd molar was evaluated. Exclusionary criteria included any roots that were dilacerated, curved, bayonet, or sickle-shaped. Known retreatments were also excluded. For this academic year at this institution, students in their 3rd year of undergraduate dental education were instructed only by
Several Scandinavian studies (l 3) have addressed the technical standard of endodontic therapy in various patient samples from that region of the world. These studies have suggested that in only 40 to 70% of the cases was the quality of endodontic therapy technically satisfactory. A more recent survey on an American subgroup of patients from Connecticut (4) also suggested that only 42% of the obturations could be considered technically satisfactory. These surveys evaluated the clinical results of dentists in general without regard to the dentist's specialization or current level of education. One of the most recent studies comparing subgroups of clinicians was a manuscript published by Molven (5) in Norway, who compared obturated teeth among general practitioners, dental students, and an endodontist. He suggested that general practitioners were subject to varying the apical extent of their obturations relative to
461
Journal of Endodontics
Mayhew et al.
462
TABLE 2. Presence of overfills
TABLE 1. Mean obturation quality rankings
Raters
Treatment Group Mean Ranks Raters
Residents
3rd Year
4th Year*
)(2
A
p
B
C
E
A B C
27.95 25.41 26.05
29.23 32.45 32.27
43.32 42.64 42,18
8.68 8.96 7.91
0.013 0.011 0.019
All experimental treatment versus residents (control} comparisons are significant, exceeding the critical value of 12 79 (p < 0 05). •
endodontic faculty in their delivery of endodontic therapy. The 4th year students were instructed by the general dentistry faculty, with occasional consults from the endodontic section. Films were mounted in single film cardboard mounts and labeled with a random six-digit code that had absolutely no relation to any group or person. Three clinicians independently rank-ordered the technical quality of the obturated canals according to the criteria cited by Odesjo (6). Two of the clinicians were endodontists (one board certified and one board eligible), and the third a board-certified general dentist (American Board of General Dentistu). The films were viewed in a darkened room on a masked X-ray viewer with ×2 magnification. Each of the 66 radiographs was ranked from 1 to 66, based on the quality of obturation of the apical half of all the canals present. Each subgroup of 22 cases was also evaluated tot the presence of overfills of one or more of the canals. A canal was considered overfilled if the canal obturation material was closer to the radiographic apex than 1 mm or extended beyond the radiographic apex. To determine whether significant differences in quality of obturation rankings existed among the three treatment groups, three Kruskal-Wallis analyses were conducted using SPSS for MS Windows (release 6.1). One Kruskal-Wallis test was conducted for each of the three raters' quality of obturation rankings. In each case, if the Kruskal-Wallis test was significant, nonparametric post-hoc multiple comparisons to the control were then conducted using the computational procedures of Miller (7) as delineated in Hollander and Wolfe (8). To determine whether significant differences in presence of overfills existed among the three treatment groups, three X2 tests for contingency tables (91 were conducted, again using SPSS. A separate X2 test was conducted for each of the three raters" presence of overfill counts. lnterrater reliability was assessed using SPSS to compute Kendall's W (10) for the three sets of rankings. The more interpretable associated average Spearman coefficient among all possible pairs of raters was then computed from Kendall's W using the equation presented by Hays (10).
RESULTS Kruskal-Wallis tests performed on each of the three independent sets of rankings of quality of the obturated canals consistently revealed significant differences (p < 0.02) among the three treatment groups {Table 1). More specifically, nonparametric post-hoc tests for multiple comparisons to a control treatment (7, 8), compared with the 3rd year endodontic students, monitored and instructed only by endodontic faculty, and the 4th year students, instructed by general dentistry faculty, each with the endodontic resident controls. Results of these tests showed that the quality of
Residents 3rd year 4th year )(2 p
Yes
No
Yes
No
Yes
No
8 11 9
14 11 13
12 12 12
12 12 12
12 9 9
10 11 1I
0.868 0,648
0.00 1.00
1.10 0.577
the obturated canals was consistently ranked significantly lower (p < 0.05) for the 4th year students than for the endodontic residents in all three sets of rankings (Table 1). On the other hand, the difference between the 3rd year students" quality and the residents' was not statistically significant. There were no significant differences in number of overfills among the three treatment groups for any of the three raters (Table 2). Interrater reliability assessments for the three sets of rankings provided a Kendall's W of 0.722, which yields an average Spearman coefficient (10) of 0.583 when converted to this more interpretable reliability index. This suggests that the raters, on balance, tended to provide relatively similar rankings.
DISCUSSION In developing this project, the authors anticipated that the null hypothesis would prevail. The dental literature in this area is sparse and the potential for dealing with confounding variables was above average. Operator skill, and participation of faculty, patient, and tooth factors all v~ied during the delivery of care; however, these were assumed to be randomly distributed across all groups. Such factors as the morphology of the roots and history of preliminary pulpectomy were found by Molven (5) to be noncontributory factors. Furthermore, available instrumentation and radiographic techniques were identical between the groups. The endodontic faculty were all board-eligible or board-certified endodontists, whereas only 4 of 23 of the general dentistry faculty teaching 4th year students had any formal training in advanced education in general dentistry. Forty-five percent of the clinical instruction provided to 4th year students came from parttime faculty who, generally, were practicing in the community. At the time, there was no intramural practice opportunity for full-time faculty. In a number of private general dentistry practices, molar endodontics is referred to a specialist for finaficial reasons (i.e. it may not be financially remunerative to have the necessary organization and efficiency to compete effectively for available "third-party" endodontic fees in light of the skill and motivation necessary to concentrate on other types of delivery of dental care. This may explain why the instruction from the general dentistry faculty may not have been as focused as that provided by the endodontic faculty. There are other indirect academic factors that impact upon lull-time general dentistry faculty as well. A high level of clinical acumen in all phases of general dentistry is challenging in light of the requirements for research and service, which are the leading factors for promotion and tenure in the academic setting. To be sure, endodontic faculty face the same academic pressures, but
VoI. 25, No. 6, June 1999
their research is generally focused on their specialty. Furthermore, board certification is expected of specialty faculty for career progression. In this particular case, the rewards of participation in other interests by the general dentistry faculty may have diffused the attention to detail needed to guide a student to the same outcome as that provided by the endodontic faculty. These results suggest that it may be appropriate to have endodontists instructing students through all of their undergraduate endodontic clinical experiences to refine and reinforce the skills necessary for a continuing high technical standard of care. However, the results of this study may also be site-specific and not generalizable to other institutions where all 4th year clinical experiences are instructed by general dentistry faculty. Concentrating on the basics of therapy (such as access, and cleaning and shaping techniques) may be the essential factor: this could be provided by general dentists, with additional education in endodontic therapy, who are well motivated and focused to teach those skills to undergraduate students. Dr. Mayhew is clinical associate professor, Department of Health Promotion and Dental Care Delivery, University of Texas Health Science CenterHouston, Dental Branch, Houston, TX. Dr. Svec is associate professor, Division of Endodontics, University of Texas Health Science Center-Houston, Dental Branch, Houston, TX. Dr. Johnson is associate professor, Department of Health Informatics, University of Texas Health Science Center, School of Allied Health Sciences, Houston, TX. Dr. Makins is assistant professor, Division of Endodontics and Section of Radiology, Department of General Dentistry, University of Texas Health Science Center-Houston, Dental Branch,
Student Cases, Quality of Fill, and Faculty Instruction
463
Houston, "iX. Address requests for reprints to Dr. Robert B. Mayhew, 6314 Lewis Lane, Rosharon, TX 77583.
References 1. Eckerbom M, Andersson J-E, Magnusson T. Frequency and technical standard of endodontic treatment in a Swedish population. Endod Dent Traumato11987;3:245-8. 2. Eriksen HM, Bjertness E, Orstavik D. Prevalence and quality of endodontic treatment in an urban adult population in Norway. Endod Dent Traumatot 1988;4:122-6. 3. Eckerbom M, Andersson J-E, Magnusson T. A longitudinal study of changes in frequency and technical standard of endodontic treatment in a Swedish population. Endod Dent Traumato11989;5:27-31. 4. Buckley M, Spangberg LSW. The prevalence and technical quality of endodontic treatment in an American subpopulation. Oral Surg Oral Med Oral Patho11995;79:92-100. 5. Molven O. The apical level of root fillings. Acta Odontol Scand 1976; 34:89 -105. 6. Odesjo B, Heliden L, Salonen L, Langeland K. Prevalence of previous endodontic treatment, technical standard and occurrence of periapical lesions in a randomly selected adult, general population. Endod Dent Traumatol 1990;6:265-72. 7. Miller RG Jr. Simultaneous statistical inference. New York: McGrawHill, 1966. 8. Hollander M, Wolfe DA. Nonparametric statistical methods. New York: John Wiley & Sons, 1973:130-1. 9. Roscoe JT. Fundamental research statistics for the behavioral sciences. 2nd ed. New York: Holt, Rinehart & Winston, 1975:254-63. 10. Hays WL. Statistics. 3rd ed. New York: Holt, Rinehart & Winston, 1981:606-8.
Printed in U.S.A. VOL. 25, No. 6, JUNE 1999
Quality of Obturation in Student Cases Instructed by Endodontic Versus General Dentistry Faculty Robert B. Mayhew, DMD, PhD, Timothy A. Svec, DDS, MS, Craig W. Johnson, PhD, and Scott R. Makins, DDS
Endodontic literature suggests that only about 60% of endodontic therapy meets current technical standards and that general dentists may be making a significant contribution to this compromised care. If so, where in the continuum of dental education does this begin. This study evaluated the quality of obturation in mandibular molars provided on the one hand by 3rd year dental students instructed by endodontic faculty, and on the other hand by 4th year students instructed by general dentistry faculty, versus the quality of obturation achieved by endodontic residents who served as a control for both groups. Final radiographs were chosen from students in all three groups so that there were 22 samples per group. Three evaluators rank-ordered the radiographs. In order of excellence, the results were: (a) residents, (b) 3rd year students, and (c) 4th year students. There was no significant difference between the 3rd year students or the residents, only between residents and 4th year students (p < 0.05). The reasons for this outcome may range from dental school objectives to the private practice procedures of the general dentists who instructed the 4th year students.
the radiographic apex to a significantly greater degree than undergraduate students or an endodontist. Clinical application of endodontic techniques for undergraduate dental students is usually concentrated in the 3rd and 4th years of the dental curriculum within American Association of Dental Schools member institutions. Most 3rd year students are monitored and instructed by endodontic faculty. The 4th year endodontic experience may be monitored by faculty with various levels of expertise, from general practitioners only to endodontic specialists only. Simulation of the private practice situation, in which only the more difficult cases are referred to specialists, is the general premise for using only general dentistry faculty in the 4th year. If, globally, 60% of endodontic obturations are not technically satisfactory, and if general dentists may be making a significant contribution to this compromised care, where in the continuum of dental education is a compromised standard accepted, if at all? In an effort to address this question at art early phase of the continuum, this study compared the quality of obturation in mandibular molars treated by 3rd year dental students who were instructed by endodontic faculty to obturations performed by I st year endodontic residents serving as a control standard. The quality of obturation provided by 4th year students instructed by the general dentistry faculty was then also compared with the same endodontic resident case serving as a control.
METHODS Final radiographs were chosen randomly from one case of mandibular molars per student from students ranked in the top 50% of both the 3rd and 4th year classes for the academic year 19941995 at this institution. In addition, 2 cases from each of I1 endodontic residents enrolled between 1990 and 1995 were selected; these were the first two mandibular molars that each resident treated. This group was treated as the control group in the statistical evaluation of the results. For the evaluation, there were 22 cases from each of the three groups. Only one view of each completed case of a mandibular 1st oi 2nd molar was evaluated. Exclusionary criteria included any roots that were dilacerated, curved, bayonet, or sickle-shaped. Known retreatments were also excluded. For this academic year at this institution, students in their 3rd year of undergraduate dental education were instructed only by
Several Scandinavian studies (l 3) have addressed the technical standard of endodontic therapy in various patient samples from that region of the world. These studies have suggested that in only 40 to 70% of the cases was the quality of endodontic therapy technically satisfactory. A more recent survey on an American subgroup of patients from Connecticut (4) also suggested that only 42% of the obturations could be considered technically satisfactory. These surveys evaluated the clinical results of dentists in general without regard to the dentist's specialization or current level of education. One of the most recent studies comparing subgroups of clinicians was a manuscript published by Molven (5) in Norway, who compared obturated teeth among general practitioners, dental students, and an endodontist. He suggested that general practitioners were subject to varying the apical extent of their obturations relative to
461
Journal of Endodontics
Mayhew et al.
462
TABLE 2. Presence of overfills
TABLE 1. Mean obturation quality rankings
Raters
Treatment Group Mean Ranks Raters
Residents
3rd Year
4th Year*
)(2
A
p
B
C
E
A B C
27.95 25.41 26.05
29.23 32.45 32.27
43.32 42.64 42,18
8.68 8.96 7.91
0.013 0.011 0.019
All experimental treatment versus residents (control} comparisons are significant, exceeding the critical value of 12 79 (p < 0 05). •
endodontic faculty in their delivery of endodontic therapy. The 4th year students were instructed by the general dentistry faculty, with occasional consults from the endodontic section. Films were mounted in single film cardboard mounts and labeled with a random six-digit code that had absolutely no relation to any group or person. Three clinicians independently rank-ordered the technical quality of the obturated canals according to the criteria cited by Odesjo (6). Two of the clinicians were endodontists (one board certified and one board eligible), and the third a board-certified general dentist (American Board of General Dentistu). The films were viewed in a darkened room on a masked X-ray viewer with ×2 magnification. Each of the 66 radiographs was ranked from 1 to 66, based on the quality of obturation of the apical half of all the canals present. Each subgroup of 22 cases was also evaluated tot the presence of overfills of one or more of the canals. A canal was considered overfilled if the canal obturation material was closer to the radiographic apex than 1 mm or extended beyond the radiographic apex. To determine whether significant differences in quality of obturation rankings existed among the three treatment groups, three Kruskal-Wallis analyses were conducted using SPSS for MS Windows (release 6.1). One Kruskal-Wallis test was conducted for each of the three raters' quality of obturation rankings. In each case, if the Kruskal-Wallis test was significant, nonparametric post-hoc multiple comparisons to the control were then conducted using the computational procedures of Miller (7) as delineated in Hollander and Wolfe (8). To determine whether significant differences in presence of overfills existed among the three treatment groups, three X2 tests for contingency tables (91 were conducted, again using SPSS. A separate X2 test was conducted for each of the three raters" presence of overfill counts. lnterrater reliability was assessed using SPSS to compute Kendall's W (10) for the three sets of rankings. The more interpretable associated average Spearman coefficient among all possible pairs of raters was then computed from Kendall's W using the equation presented by Hays (10).
RESULTS Kruskal-Wallis tests performed on each of the three independent sets of rankings of quality of the obturated canals consistently revealed significant differences (p < 0.02) among the three treatment groups {Table 1). More specifically, nonparametric post-hoc tests for multiple comparisons to a control treatment (7, 8), compared with the 3rd year endodontic students, monitored and instructed only by endodontic faculty, and the 4th year students, instructed by general dentistry faculty, each with the endodontic resident controls. Results of these tests showed that the quality of
Residents 3rd year 4th year )(2 p
Yes
No
Yes
No
Yes
No
8 11 9
14 11 13
12 12 12
12 12 12
12 9 9
10 11 1I
0.868 0,648
0.00 1.00
1.10 0.577
the obturated canals was consistently ranked significantly lower (p < 0.05) for the 4th year students than for the endodontic residents in all three sets of rankings (Table 1). On the other hand, the difference between the 3rd year students" quality and the residents' was not statistically significant. There were no significant differences in number of overfills among the three treatment groups for any of the three raters (Table 2). Interrater reliability assessments for the three sets of rankings provided a Kendall's W of 0.722, which yields an average Spearman coefficient (10) of 0.583 when converted to this more interpretable reliability index. This suggests that the raters, on balance, tended to provide relatively similar rankings.
DISCUSSION In developing this project, the authors anticipated that the null hypothesis would prevail. The dental literature in this area is sparse and the potential for dealing with confounding variables was above average. Operator skill, and participation of faculty, patient, and tooth factors all v~ied during the delivery of care; however, these were assumed to be randomly distributed across all groups. Such factors as the morphology of the roots and history of preliminary pulpectomy were found by Molven (5) to be noncontributory factors. Furthermore, available instrumentation and radiographic techniques were identical between the groups. The endodontic faculty were all board-eligible or board-certified endodontists, whereas only 4 of 23 of the general dentistry faculty teaching 4th year students had any formal training in advanced education in general dentistry. Forty-five percent of the clinical instruction provided to 4th year students came from parttime faculty who, generally, were practicing in the community. At the time, there was no intramural practice opportunity for full-time faculty. In a number of private general dentistry practices, molar endodontics is referred to a specialist for finaficial reasons (i.e. it may not be financially remunerative to have the necessary organization and efficiency to compete effectively for available "third-party" endodontic fees in light of the skill and motivation necessary to concentrate on other types of delivery of dental care. This may explain why the instruction from the general dentistry faculty may not have been as focused as that provided by the endodontic faculty. There are other indirect academic factors that impact upon lull-time general dentistry faculty as well. A high level of clinical acumen in all phases of general dentistry is challenging in light of the requirements for research and service, which are the leading factors for promotion and tenure in the academic setting. To be sure, endodontic faculty face the same academic pressures, but
VoI. 25, No. 6, June 1999
their research is generally focused on their specialty. Furthermore, board certification is expected of specialty faculty for career progression. In this particular case, the rewards of participation in other interests by the general dentistry faculty may have diffused the attention to detail needed to guide a student to the same outcome as that provided by the endodontic faculty. These results suggest that it may be appropriate to have endodontists instructing students through all of their undergraduate endodontic clinical experiences to refine and reinforce the skills necessary for a continuing high technical standard of care. However, the results of this study may also be site-specific and not generalizable to other institutions where all 4th year clinical experiences are instructed by general dentistry faculty. Concentrating on the basics of therapy (such as access, and cleaning and shaping techniques) may be the essential factor: this could be provided by general dentists, with additional education in endodontic therapy, who are well motivated and focused to teach those skills to undergraduate students. Dr. Mayhew is clinical associate professor, Department of Health Promotion and Dental Care Delivery, University of Texas Health Science CenterHouston, Dental Branch, Houston, TX. Dr. Svec is associate professor, Division of Endodontics, University of Texas Health Science Center-Houston, Dental Branch, Houston, TX. Dr. Johnson is associate professor, Department of Health Informatics, University of Texas Health Science Center, School of Allied Health Sciences, Houston, TX. Dr. Makins is assistant professor, Division of Endodontics and Section of Radiology, Department of General Dentistry, University of Texas Health Science Center-Houston, Dental Branch,
Student Cases, Quality of Fill, and Faculty Instruction
463
Houston, "iX. Address requests for reprints to Dr. Robert B. Mayhew, 6314 Lewis Lane, Rosharon, TX 77583.
References 1. Eckerbom M, Andersson J-E, Magnusson T. Frequency and technical standard of endodontic treatment in a Swedish population. Endod Dent Traumato11987;3:245-8. 2. Eriksen HM, Bjertness E, Orstavik D. Prevalence and quality of endodontic treatment in an urban adult population in Norway. Endod Dent Traumatot 1988;4:122-6. 3. Eckerbom M, Andersson J-E, Magnusson T. A longitudinal study of changes in frequency and technical standard of endodontic treatment in a Swedish population. Endod Dent Traumato11989;5:27-31. 4. Buckley M, Spangberg LSW. The prevalence and technical quality of endodontic treatment in an American subpopulation. Oral Surg Oral Med Oral Patho11995;79:92-100. 5. Molven O. The apical level of root fillings. Acta Odontol Scand 1976; 34:89 -105. 6. Odesjo B, Heliden L, Salonen L, Langeland K. Prevalence of previous endodontic treatment, technical standard and occurrence of periapical lesions in a randomly selected adult, general population. Endod Dent Traumatol 1990;6:265-72. 7. Miller RG Jr. Simultaneous statistical inference. New York: McGrawHill, 1966. 8. Hollander M, Wolfe DA. Nonparametric statistical methods. New York: John Wiley & Sons, 1973:130-1. 9. Roscoe JT. Fundamental research statistics for the behavioral sciences. 2nd ed. New York: Holt, Rinehart & Winston, 1975:254-63. 10. Hays WL. Statistics. 3rd ed. New York: Holt, Rinehart & Winston, 1981:606-8.