Opinions of UK General Dental Practitioners on the Restoration of Posterior Root Filled Teeth: a Vignette Survey

Objective: To investigate factors which influence UK general dental practitioners (GDPs) when restoring posterior root filled teeth. Method: An electronic survey was designed to explore current strategies of treatment of posterior root filled teeth by UK-based GDPs working in primary care. Three vignette cases included in the questionnaire explored a variety of tooth, patient, and financial factors. The survey was distributed by email and social media platforms between December 2018 and February 2019. Results: A total of 528 valid responses were collected. The majority of participants (84.1%) regularly restored posterior root filled teeth with an indirect restoration. Presence of persistent symptoms post root canal treatment (RCT) completion would impact the management of 85% of the surveyed respondents. Referral to a specialist, deferral of provision of the definitive restoration, and fear of litigation were reported by the GDPs as influencing factors. Conclusion: This survey highlights that decision making regarding restoration of root filled teeth is a multifactorial process. Tooth, patient, and financial factors were all shown to influence the restorative management of the posterior root filled teeth.


Learning Objectives
• To explore different restorative challenges faced by general dental practitioners by using a vignette survey • To determine the factors influencing general dental practitioners when restoring root filled teeth • To understand how dentists' experience, fee structure and location influences restorative management of root filled teeth OpiniOns Of UK general denTal pracTiTiOners On The resTOraTiOn Of pOsTeriOr rOOT filled TeeTh: a vigneTTe sUrvey introduction root canal treatment (rCt) in the uK is predominantly provided by general dental practitioners (GDPs), with over 500,000 endodontic treatments completed annually in the nHs alone (pre CoViD-19 pandemic 2018/2019). 1 a large proportion of root filled teeth usually present with significant loss of coronal tooth structure due to existing restorations and caries.3][4] it is therefore vital to provide a suitable coronal restoration on a root filled tooth, to increase endodontic success rates.6][7][8] However, these mainly focused on provision of posts and the information was obtained with closed-ended multiple choice questions, collecting limited information.
a recent systematic review by Bhuva et al. 9 reported better long-term survival outcomes for posterior root filled teeth restored with indirect cuspal coverage restorations, when compared with those restored with direct restorations.it has also been shown that multiple factors affect long term survival of root treated teeth, such as the amount of residual tooth structure left, presence of marginal ridges and tooth location.
in the uK there is currently limited data on what factors affect a dentist's decision-making process when restoring posterior root filled teeth.research is also lacking on the cost of endodontic treatment and how a patient's paying status affects the choice of restoration they receive.the aim of this study was to explore and identify the factors which GDPs may take into consideration when restoring a posterior root filled tooth.

Methods
this study was a cross-sectional observational electronic survey with a 33-item questionnaire designed and hosted with Qualtrics Xm 2018 (Qualtrics, Provo, ut, usa).the survey allowed answers in formats such as text entry, multiple choice, or a drop-down menu of options.ethical approval was   Postgraduate experience of the GDPs showed a clear trend in older and experienced GDPs opting for direct restorative approaches more often, when restoring root filled teeth.this may be a result of differences in approaches taught during their BDs degree, with recent graduates being encouraged to use indirect restorations when restoring root filled teeth.Despite the GDC's compulsory continuing professional development (CPD) requirements, restorative dentistry CPD is not mandatory. 12Consequently, it's possible that this is one of the main reasons for the disparities in restoration trends that are evident in the data.
experienced dentists may also be more confident in their abilities and likely to employ direct restorative materials more predictably, in comparison to their younger colleagues.
the vignettes were designed to explore how different factors influence GDPs' restorative management of the root filled teeth.these include tooth, patient, and financial factors and are discussed below.

tooth related factors
Vignettes 1 and 3 both feature teeth which have lost their marginal ridges.mondelli et al. 11 have suggested that the loss of marginal ridges weakens the tooth, with a mesio-occlusal restoration reducing stiffness by as much as 63%. 13he majority of GDPs in this survey chose to use an indirect cuspal coverage restoration to restore posterior root filled teeth, which reflects the findings seen in other studies.14,15 Current evidence regarding restoration of posterior root filled teeth is conflicting, which can explain the variety of responses collected in this survey.systematic reviews by Bhuva et al. and stavropoulou and Koidis report an increased survival rate of indirectly restored root treated teeth, compared to use of a direct restorative approach.9,16 However, a review by sequeira-Byron et al. 17 states that there is not currently enough evidence to recommend the use of an indirect restoration to restore a root filled tooth.
Bruxist patients often present with tooth wear and are at higher risk of tooth and restoration fracture.this is especially relevant in root treated teeth due to the increased amount of force applied on chewing motions and reduction in periodontal ligament (PDl) proprioception. 18this topic was explored in Vignette 3, with 79.6% of GDPs choosing to restore the lr5 with an indirect restoration.evidence of bruxism would alter the management of 55% of the surveyed practitioners.this was mainly due to a provision of a metal cuspal coverage restoration instead of porcelain, due to higher fracture and wear resistance.

patient factors
the provision of an indirect coronal restoration can be influenced by the caries risk status of the patient, which was explored in Vignette 1. Patients with a high rate of caries are likely to develop secondary caries, subsequently leading to restoration failure.therefore, it is advised that more complex treatment such as indirect restorations should be deferred until the caries rate has reduced and no new carious lesions are present. 19in Vignette 1, only 39% of the surveyed GDPs would choose to change their management in a high caries risk OpiniOns Of UK general dental practitiOners On the restOratiOn Of pOsteriOr rOOt filled teeth: a vignette sUrvey ViGnette 1: summary anD surVey results a 21-year-old fit and well male patient requires restoration of the root treated ur6.radiographically the ur6 has a well-obturated root filling to length with no voids and no periapical area.
Prior to the rCt, the tooth had a draining sinus and was symptomatic.
Presently, the tooth is asymptomatic.the patient has a minimally restored dentition and low periodontal risk, class 1 occlusion and no tooth surface loss.ViGnette 2: summary anD surVey results an 18-year-old fit and well female patient had root canal treatment on the lr6 due to irreversible pulpitis.radiographically the lr6 is well obturated to length in the mesial roots; the obturation is 3mm short in the distal root but has no periapical lesion.the patient has an anterior open bite, good oral hygiene, and good periodontal health.ViGnette 3: summary anD surVey results a 40-year-old fit and well male presents with pain from the lr5.

Distribution (%)
after completion of rCt, symptoms resolved within one week.radiographically the lr5 is well obturated to length with no voids or radiographic signs of a periapical area.the patient has a class 1 occlusion, no tooth surface loss, minimally restored dentition, low caries risk and good oral and periodontal health. (Continued) OpiniOns Of UK general dental practitiOners On the restOratiOn Of pOsteriOr rOOt filled teeth: a vignette sUrvey patient, by deferring the provision of the definitive restoration or extracting the tooth.the remaining practitioners stated that the need to achieve a good coronal seal and risk of complaint due to incomplete treatment would influence them to restore the tooth as planned.
litigation has now become more common in general dental practice, ranging from contractual disputes to patient complaints. 20in comparison with other health professions, GDPs regularly undertake multiple high-risk operative procedures, which may place them at an increased risk of litigation.the majority of the surveyed participants (85.4%) would alter their management of the ur6 in Vignette 1 if the patient had persistent symptoms after the rCt. the survey responses indicated that, to minimise the risk to the GDP, referral to a specialist for a second opinion or ruling out non-odontogenic pain as an alternative underlying cause were suggested as effective measures.according to nixdorf et al., it is not unusual for non-odontogenic pain to occur as a result of root canal therapy, and it could account for up to 50% of all cases of persistent tooth pain. 21However, the prevalence of post-operative pain after rCt completion is well documented 22 and therefore a small proportion of  23 exempt patients are also more likely to have lower socio-economic status and present with higher treatment needs. 24taking these factors into consideration, Vignettes 1 and 2 explored if the patients' paying status would influence the GDPs restorative management.more than 70% of surveyed dentists reported that this factor would not influence their treatment plan.However, as seen in the results of both vignettes, a minority of GDPs reported that the factor of nHs exemption status may alter their decision, which was further highlighted in the free text responses.reasons, such as lack of financial risk to the patient if treatment fails or provision of indirect restoration to offset the clinical time of rCt by qualifying for a higher uDa rate, were reported by the surveyed GDPs.][27] in addition to a patient's nHs paying status, multiple other confounding factors also need to be considered, which could affect a GDP's decisionmaking process.the authors speculate that these could include a patient's higher caries risk and higher prevalence of caries, therefore other treatment modalities could be more suitable for those exempt nHs patients.

Limitations
one of the clear limitations of this study is the lack of clinical and radiographic information supplied in the vignettes, therefore the results should be viewed with caution.
the intention of this study was not a direct simulation of clinical practice cases; the vignettes were designed to help identify and understand the trends within general dental practice and GDPs' attitudes to the restoration of posterior root filled teeth.
the majority of responses collected for the survey were obtained through a social media link.this was highly effective in collecting data, however it isolates dentists who have limited access to computers and are less familiar with social media based professional groups.subsequently the most experienced dentists, with over 20 years post qualification, made up less than a quarter of participants.a postal survey option could have been used to reach those practitioners, to ensure accurate representation of the survey sample.
Finally, the limitations of selfassessment and use of questionnaires need to be considered when interpreting the results of this study.Particularly, social desirability bias which favours overreporting of "good" behaviour and omitting "bad" behaviour may be prevalent in a vignette survey setting.
conclusion the responses to the vignettes presented in this survey show that decision-making for the restoration of the root filled posterior tooth is a complex process.it can be influenced by many factors, summarised below.

tooth factors
remaining tooth structure was the main factor for the GDP with respect to restoring root filled posterior teeth.missing marginal ridges and parafunctional habits increased the likelihood of provision of an indirect restoration.

patient factors
High caries risk and persistent symptoms were important factors to most of the GDPs surveyed and were shown to defer the provision of the definitive restoration.

financial factors
From this study, there is evidence to suggest that finances can drive treatment decisions.although for the majority of GDPs, finances wouldn't change their management, a patient's fee-paying status may change a dentist's approach to care due to complexity of patient needs.
Free text answers summary restoration choice of the lr6 indirect 68.4 High risk of fracture due to occlusion.Provision of cuspal protection Direct 31.6 easy to place.marginal ridges intact Would your management change if the patient had class 1 occlusion and no signs of tooth wear?

Did you feel sufficiently trained as an undergraduate to restore root filled teeth?
5%), and northern ireland (1%).this closely matches the GDC reported figures of uK GDPs. 10 the age of the survey participants shows a similar pattern, however a greater proportion of younger dentists participated in the survey compared to the uK demographic data. 10most respondents worked in full nHs practice the three vignette cases and associated summaries of the responses are presented in tables 5, 6 and 7. additional analysis of responses to the vignettes by fee structure and region is shown in table 8. it indicates that GDPs from both nHs and private practices restore root filled teeth similarly, however private dentists prefer using indirect restorations which can be seen across all three vignettes.the collected data also shows that scottish nHs dentists are far more likely to use direct restorative approaches in all vignette cases.