Mittelsteadt_unc_0153M_18637.pdf

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INFLUENCE OF CLINICIAN BACKGROUND ON SURGERY VS. RETREATMENT RECOMMENDATIONS

Michael Mittelsteadt

A thesis submitted to the faculty at the University of North Carolina at Chapel Hill in partial fulfillment of the requirements for the degree of Masters in Science in the

Department of Endodontics in the School of Dentistry

Chapel Hill 2019

Approved by:

Peter Tawil

Siggi R. Saemundsson

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iii ABSTRACT

Michael Mittelsteadt: Influence of Clinician Background on Surgery vs. Retreatment Recommendations

(Under the direction of Peter Tawil)

This study analyzed the influence of clinician experience, training quality, and other clinician-specific factors on treatment recommendations for infected teeth with previous endodontic treatment. A survey was sent to members of the American Association of Endodontists which evaluated the aforementioned factors in addition to obtaining each participant’s initial treatment recommendations for a set of

endodontically treated teeth (surgery vs. retreatment). Primary analysis evaluated the relationship of clinician background on the ratio of surgery to retreatment recommendations. No correlation was found between surgery to retreatment ratio with any training related factors. Data did reveal that, while satisfied with both retreatment and surgical training in residency, endodontists are more satisfied with that of nonsurgical retreatment.

Overall, this survey showed that endodontists are predisposed to electing retreatment over surgery. Among the variables explored to explain this trend,

experience with CBCT in residency was associated with an increase in proportion of cases recommended for surgery. Gender, continuing education, and general

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TABLE OF CONTENTS

List of Tables . . . . .. . . v

List of Figures . . . .. . . vi

Thesis Introduction . . . 1

Review of Literature . . . 2

Formatted Sections for the Journal of Endodontics i: Introduction . . . 9

ii: Materials and Methods . . . .. . . 11

a. Data Collection . . . .11

b. Analysis. . . .12

iii: Results . . . 12

iv: Discussion . . .. . . 17

v: Conclusion . . . . . 19

vi: References . . . 20

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v

LIST OF TABLES

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vi

LIST OF FIGURES

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Thesis Introduction

Proper diagnosis combined with an ideal treatment plan is essential in dental care. Endodontists face uniquely challenging diagnoses on a regular basis and must take into consideration many confounding factors, especially when planning treatment an infected tooth with prior endodontic treatment. There are several treatment options endodontists must consider. These typically include retreatment, apical microsurgery, and extraction. The literature suggests that retreatment and surgical treatment have advantages over one another depending on the etiology and clinical situation (1). However, data reported in the literature is likely not the only driving factor guiding an endodontist’s treatment decision (2,3).

Evidence of data-driven treatment decisions would be the ideal, reflecting minimal variability in skill and knowledge among endodontists. The volume and quality of intra- and post-residency surgical training, clinical experience, and gender are all potential clinician-specific variables that may contribute to treatment planning

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Review of the Literature

Treatment prognosis is among the most important factors clinicians must consider when advising patients on management of a root canal with persistent or recurrent apical pathology. On the subject of retreatment and apical surgery prognosis, there are a wide variety of data reported on this subject. This can be both informative and challenging to clinicians attempting to make conclusions regarding the best treatment to offer.

Non-surgical retreatment has been reported to have a prognosis ranging a minimum span of 69% to 95% (4–7). Like any procedure in dentistry and medicine, there are preoperative and intraoperative variables which may modulate the prognosis of a particular case. Perhaps the most powerful predictor of retreat success is the preoperative presence or absence of apical periodontitis. In the absence of apical periodontitis, a clinician can expect 90-98% treatment success (5,6,8,9). However, when present, one can expect success rates to drop to an average success rate of 74-84% (5,6,9,10). Therefore, factors relating to healing or non-healing of apical

periodontitis are therefore of utmost importance to a clinician.

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complications that may be present from the prior treatment in order to clean and shape the root canal system properly (7). When these prior complications resulted in

irreversible damage to the tooth or rendered the canals uninstrumentable, Gorni and Gagliani demonstrated a less than 50% rate of retreatment success (7).

Other unseen prognostic factors are often at play with persistent apical

periodontitis. Matured bacterial biofilms which are resistant to standard irrigation and instrumentation protocols may be present (12). Anatomical variations such as isthmuses and accessory canals may also reduce standard irrigation efficacy (13,14). Furthermore, root fractures, which may themselves have instigated the apical periodontitis, often go undetected and may never be fully appreciated without surgical visualization (15,16). There is even evidence that the stresses of retreatment may themselves cause root fractures (17). Other nosocomial complications may be more likely when a complex restoration or post must be removed (18). A complex restoration is perhaps one of the most influential factors which may dissuade a clinician from recommending retreatment (2).

The advent of modern microsurgical techniques has elevated apical surgery from a treatment of last-resort to a predictable primary treatment option for treating persistent apical periodontitis. Setzer reported a 59% success rate when traditional techniques were used compared to the 94% success rate of modern techniques (19). This rate is consistent with other treatment outcome reports from the past decade when ultrasonic root end preparation and acceptable root-end fill materials were used (13,20–23).

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periodontal communication of an apical lesion will lower success rates below 80% (22). Tawil found that the presence of dentinal defects after root-end resection is also a negative prognostic factor (21). Furthermore, large lesion size has also been attributed to lower success rates (24,25).

In spite of these modulating factors, the high reported success rates of modern microsurgery are relatively consistent and predictable. This is likely related to the the relative independence from primary root canal treatment complications. Thus, it takes a closer look to understand why clinicians often avoid surgery. Perhaps among the

greatest factors that may sway operators away from recommending this treatment option are the risk of late-failure and poor operator skill.

Late failure of surgeries is a valid concern. It is well documented in the literature that teeth treated with apical surgery may heal initially, then subsequently relapse with recurrent apical periodontitis. This has been demonstrated with both traditional (1,15,26) and modern surgical technique (26). In considering this possibility, it is important to note the two most plausible reasons for failure: overwhelming bacterial leakage through the root-end fill and vertical root fracture.

Endodontists concerned about the former mode of failure may be biased toward recommending retreatment if they do not have a complete history of the previous

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are many root canals completed in the United States below the standard of care (28). These factors are compounded by the rare but real possibility that a tooth’s root fill material, while perhaps radiographically sound, may in some cases be fully degraded (29). Surely many clinicians would lean toward at least initially retreating a root canal system that they knew was contaminated through and through as opposed to apical surgery, which would simply entomb the residual bacteria.

While the aim at providing patients with a fully disinfected root canal system is admirable, it is important to note that the fear of surgical failure due to leakage with modern micro-surgical technique may not be an evidence-based phobia. Von Arx demonstrated that the most common mode of microsurgical failure was root fracture. Tooth-type was a significant factor, with heavily-stressed mandibular molars failing, primarily from fractures, most often (26). This is a stark contrast to Riis et. al which reported less failures due to fracture than leakage with traditional surgical technique (15).

Fractures are extremely difficult to prevent with current surgical techniques. Existing dentinal defects may be present, which may worsen during the ultrasonic root-end preparation or after prolonged function (26,30). Some may be preventable with impeccable surgical technique. Evidence suggests that careful root end inspection for dentinal defects with transillumination may enable a clinician to eliminate dentinal defects instead of propagating them during ultrasonic root end preparation (30).

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endodontists face an uphill battle when it comes to maintaining and enhancing surgical technique. Compared with non-surgical retreatment which relies on a nearly identical skillset to primary endodontic treatment and restorative dentistry, endodontic

microsurgery requires a unique skillset. Burns et al. demonstrated in a multi-disciplinary survey the effect that perceived surgical complexity has a significant influence on

treatment planning. Most notably, molars were by far the least likely to be treated with apical surgery, undoubtedly due to difficulty of surgical access (2). There are few

patient-related factors for which non-surgical retreatment is contraindicated, but it is not uncommon for surgery to be avoided due to medical or other patient-specific factors. In fact, due to its heightened potential for morbidity, apical surgery has traditionally been recommended as a treatment of last-resort (32). Given this, and the stark difference in skills required, it is easy to conceive of the possibility that surgical avoidance tendencies could snowball throughout a career.

Habitual bias toward retreatment likely starts in residency. A study by Blacher et. al indicated that the majority of United States endodontics residents complete between 0 and 10 apical surgeries, compared to 26-50 non-surgical retreatments (33). While this study indicated that all residents have exposure to microscope use, CBCT training quality is variable (34). CBCT has been recommended by the American Association of Endodontists and American Academy of Oral Radiologists for surgical treatment

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treatment recommendation 62% of the time after subsequently reviewing the respective cone-beam CT volumes (36). Many of the teeth reviewed had iatrogenic perforations, resorption defects or root fractures that were not initially evident on periapical

radiographs and would only be manageable with a surgical approach. Overall, today’s endodontists and endodontics residents tend to be somewhat dissatisfied with their training in CBCT use. Residents specifically trend toward having low confidence in CBCT interpretation. This is in a stark contrast from graduate program directors who rate their offered CBCT training at 4.37/5 (34). A study by Parker et al. further built upon the importance of high quality training in CBCT interpretation. Not only are residents less confident (34), they are less proficient in interpretation of CBCT volumes compared with their faculty (37). Without adequate surgical case-load and training in CBCT

interpretation, endodontists are deprived of experience which may help them fully understand the limitations of retreatment. This national trend may be another factor that may bias endodontists toward retreatment recommendations.

Another trend in the dental profession which may have an influence on treatment planning opinions is the changing gender landscape. The proportion of women entering the United States dental workforce has drastically increased over the past 10-20 years (38). How or whether gender has an impact on endodontic treatment, especially as it pertains to surgery recommendations, is uncertain. In medicine, there is some evidence that female surgeons have lower 30 day patient mortality rates (39). Conversely,

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Overall, a better understanding of how such background and clinician-specific factors impact treatment recommendations may shed light on current treatment

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FORMATTED SECTIONS FOR THE JOURNAL OF ENDODONTICS

i. Introduction

Proper diagnosis combined with an ideal treatment plan is essential in dental care. Endodontists face uniquely challenging diagnoses on a regular basis and must take into consideration many confounding factors, especially when planning treatment of infected teeth with prior endodontic treatment. There are several treatment options endodontists must consider. These typically include retreatment, apical microsurgery, and extraction. The literature suggests that retreatment and surgical treatment have advantages over one another depending on the etiology and clinical situation (1). However, it is likely that data reported in the literature may not be the only driving factor guiding an endodontist’s treatment decision. Other aspects of a clinician’s background may shape his or her treatment philosophy, such as clinician experience, gender, and training.

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Ideally, clinicians would provide the best treatment option to the patient based on the merits of the treatment itself. Both surgical and non-surgical retreatment have

reliable prognoses reported in the literature (42,43). Non-surgical retreatment has been reported to have a prognosis ranging from 69% to 95%, with lower rates occurring when iatrogenic complications are present (4–7). Since the advent of modern surgical

techniques, the prognosis of apical microsurgery has become remarkably high. Setzer reported a 59% success rate when traditional techniques were used compared to the 94% success rate of modern techniques (19). While retreatment is a less invasive treatment option for the patient, surgery is often objectively superior when irreversible technical errors are evident in the previous treatment (7), or when orthograde

instrumentation is unlikely to properly debride the canal space. Von Arx demonstrated that the latter situation is relatively frequent, with 76% of mesiobuccal roots of previously treated maxillary first molars having isthmuses, none of which contained root fill material (13). Lack of experience and comfort with a particular option may bias a clinician

against it.

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surgical access. The same survey also demonstrated the significant intra- and inter-operator variability in treatment planning (2).

Perceived case difficulty and treatment recommendations should vary minimally among endodontists, reflecting evidence-based treatment decisions and quality training. The emphasis or lack-thereof on surgical training, combined with other potential

influences within a clinician’s background have the potential to bias a clinician treatment recommendations. Evidence for or against this possibility is lacking. Therefore, the aim of this study was to evaluate the effect of clinician training and other background influences on treatment recommendations for failed endodontically treated teeth.

Ii. Materials and Methods

a. Data Collection

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12 b. Analysis

The outcome variables are represented by the responses to the case scenarios and the responses are categorical (retreatment vs apical microsurgery). The primary explanatory variables were the number of retreatments and the number of apical microsurgeries recommended in the case series. Bivariate analysis was be performed using Student’s T-test and Chi-Square analysis. The relationship of the continuous variables in questions 2, 3, 4, 17, 18, 23, 24 with retreatment to surgery ratio was evaluated using Spearman’s correlation.

Iii. Results

Overall, 695 survey responses were recorded. The mean years in practice was 14.99 years. The mean apical surgeries in the past 12 months was 26.38 (SD 25.66) whereas the mean retreatments was 78.15 (SD 27.83). The mean number of apical surgeries during residency was 19.6 compared to 52.06 retreats. 81% of respondents were male compared to 18.49% female. 31.26% of respondents had access to a CBCT scanner during residency, however this figure rose to 70.7% for young practitioners (0-5 years experience). 70.92% of respondents had experience as a general dentist.

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16 Table 3. Results of case-based questions.

Retreatment (%) Surgery (%)

Question 5 78.85 21.15

Question 6 85.88 14.12

Question 7 65.91 34.09

Question 8 75.56 24.44

Question 9 70.02 29.98

Question 10 58.41 41.59

Question 11 47.02 52.98

Question 12 34.49 65.51

Question 13 98.38 1.62

Question 14 94.43 5.57

Figure 1. Bar graph revealing the overall quantity of surgery and retreatment recommendations by survey respondents. 1792 surgery recommendations were made, compared with 4376 retreatment recommendations.

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 N um ber o f R ec o m m enda ti o ns

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17 iv. Discussion

Based on these data, it is apparent that retreatment is the endodontist’s

treatment modality of choice for infected endodontically treated teeth. Most respondents recommended retreatment on 7-9 of the 10 cases and reporting a significantly higher number of retreatments completed in the past 12 months relative to surgeries (mean 78.2 compared to 26.4, respectively).

While surgical treatment training scores were significantly lower than retreatment, respondents reported general satisfaction with training in both treatment modalities. The mean faculty proficiency and training scores for both procedures corresponded with an “Above Average” rating. This appears to differ from Creasy et al., who reported only 66.7% of respondents being satisfied with their surgical training. Given this, it is not surprising that increasing surgery to retreatment ratio was not correlated with changes in training quality ratings. Continuing education in surgery after residency was also irrelevant to treatment recommendations. This study did, however, shed light on an aspect of residency training that may have an effect on future treatment planning: CBCT experience.

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reflect a greater understanding of the limitations of nonsurgical retreatment. Gorni and Gagliani demonstrated poor retreatment outcomes when irreversible complications from initial treatment were present (7). CBCT imaging can better reveal these errors and help clinicians avoid recommending unnecessary or poor treatment (36). While only 31.3% of respondents reported having had access to CBCT during residency, it is encouraging that this figure is far higher (70.7%) for recent graduates.

The case series presented may have played a role in the tendency toward retreatment. For one, only a periapical radiograph was provided in each case. This was done by design in order to glean treatment planning biases among clinicians given a minimum amount of information. With a cone beam CT or angled radiographs, it is possible that more surgeries would have been recommended. Furthermore, other than the presence of posts and crowns, there were few complicating factors such as

perforations or separated instruments, which may have completely precluded successful retreatment. The case in question #12 had the most surgery

recommendations of any of the cases (65.6%). Despite this case posing the most retreatment challenges (i.e., deep post, crown, little to improve upon from the initial treatment) while having a reasonably manageable surgery, over 1/3 of respondents still elected retreatment. It is possible that this is related to the fact that 43% of endodontists refer at least some of their surgeries out (3).

Gender showed no effect on proportion of retreats and surgeries recommended. In a professional landscape with increasing numbers of women (38), it is important to consider if this may modify treatment trends. While there is evidence that female

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conservative, preventative treatments compared to men (40). One can speculate that these variables may balance out.

Based on the inter-clinician variability in responses, and lack of clear correlation with many of the explanatory variables investigated in this study, it is clear that the treatment planning process of failed endodontic treatment is complex and likely influenced by a myriad of factors in a clinician’s background. Few individual variables appear to commonly constitute a significant portion of those which may sway a

clinician’s opinion toward or away from a specific treatment.

v. Conclusions

This survey to AAE members evaluated if there are influential factors in clinician background that may influence treatment planning of infected root canal treated teeth. Overall, endodontists are predisposed to electing retreatment over surgery. Experience with CBCT in residency was associated with an increase in proportion of cases

recommended for surgery. Gender, continuing education, and general practice

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THESIS CONCLUSION

Despite the improvements in the prognosis of apical surgery, which have made it at least as successful and predictable as non-surgical retreatment, there is still

significant disagreement among endodontists regarding when either treatment is indicated. It is possible that this disagreement arises from clinician-specific factors unrelated to prognosis reported in the literature. Therefore, the purpose of this study was to evaluate aspects of a clinician’s background on treatment planning for failed endodontically treated teeth, with an emphasis on evaluation of training in residency.

The data from this case-oriented survey study revealed significant variability among endodontists as to how each tooth should be treated. Despite this, there was a clear trend favoring retreatment. While there was no direct correlation with quality of training or faculty with treatment recommendation quantity, it was found that access to cone beam CT during residency had a significant positive influence on the number of surgeries recommended.

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