Race 123 Endodontic Files

[Jonelle Rycroft]

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Objectives The aim of this pooled data analysis was to establish if there is an association between a patient's race and the proportion of successful outcomes of endodontic treatments, and if so, what factors may determine this association.

Methodology Data collected from four prospective clinical outcome studies were pooled. Patients were recalled 12 months after the completion of the treatment. Treatment outcome was determined by clinical findings and cone beam computed tomography examination. Statistical analysis included the description of categorical and continuous variables and simple binary logistic regression models, chi-squared tests and Kruskal-Wallis tests.

Conclusions Black and NBME patients had a significantly higher failure rate of root canal treatments compared to white patients. All other known pre-, intra- and post-operative risk factors for root canal treatment failure were present in similar proportions in BME and white patients.

In England, 5.6 million NHS patients received root canal treatment between 2014-2015, not including privately treated cases.1 Radiographic and clinical findings have been widely accepted in research to determine the success or failure of endodontic treatments, as suggested by Strindberg in 1956.2,3,4 The success of an endodontic treatment is determined by the presence or absence of apical pathology and clinical signs and symptoms. Cone beam computed tomography (CBCT) offers a more sensitive and accurate method of detecting apical periodontitis compared to periapical radiographs.5 Outcome studies utilising CBCT scanning therefore may offer more insight into the factors that affect the outcome of endodontic treatment.6,7,8

Most clinical research is directed upon the outcomes of treatment healthcare professionals provide, focusing on the methods, materials and treatment protocols. There is substantive evidence, however, that broader social determinants impact how health care is provided. One social determinant that has been shown to impact on health and health care is race, with research showing that Black, Asian and Minority Ethnic patients often receive a lower quality of health care and are less likely to receive preventative treatments. The US Institute of Medicine published the Unequal treatment report, which also took into consideration factors which are often used to explain such racial disparities.9 This has been documented in relation to heart disease, hypertension and diabetes,10,11 as well as cancer diagnosis, including cervical, breast, colorectal, lung and prostate cancer.12,13,14,15 This has even been noted in infant mortality rates and infantile quality of care,16 with Black mothers in the UK being five times more likely to die after complications from childbirth and pregnancy compared to white women.17 While the majority of research on the relationship between race and health focuses on general health, there is a growing body of work exploring the relationship between racism and oral health inequalities.18,19,20

The terms race and ethnicity are commonly used as terms to classify human diversity; race as a broad category to group people upon their ancestral origin and physical characteristics and ethnicity as those that share a common cultural tradition, values or religion. Both are considered to be social constructs that are without scientific or biologic meaning.21 They are, however, helpful in research and are used as determinants of people's access to education, health care and when focusing on inequalities in health outcomes. The category of race has, therefore, been used in this study.22

Research on unconscious biases suggests that while some people hold conscious biases and express their prejudice beliefs openly, this is largely deemed unacceptable. In contrast, many people have unconscious biases, which may affect their decisions and actions without them being aware.

We performed a pooled analysis of four prospective clinical trials investigating the outcome of endodontic treatments, undertaken at King's College London Dental Institute. The aim of this pooled data analysis was to establish if the outcome - root canal treatment - is affected by patient race, and if so, what factors may be the cause of this inconsistency.

The inclusion criteria for the four studies have been described7,23,24,25 in the online Supplementary Information and Tables 1, 2 and 3. Common exclusion criteria included: those pregnant; unrestorable teeth; immunosuppressed patients and teeth with periodontal probing depths exceeding 3 mm; immature teeth; and teeth with internal/external root resorption. Patients who had more than one tooth treated and patients with missing information on socioeconomic background were also excluded. All patients underwent a full assessment, including routine medical and dental history, pain history and a soft and hard tissue examination. Digital periapical radiographs and CBCT scans were taken for all cases pre-operatively and 12 months after treatment as described in the original papers.23,24,25,26 Data regarding race (both patient and operator), patient medical history, root length and root curvature were extracted from patients' dental records and the likely socioeconomic status (SES) of the patient was determined via the index of multiple deprivation (IMD).27 Race was self-reported by study participants and race categories (Black and white) were defined by investigators based on the 2021 UK Census.28 An additional analysis was carried out, including grouping individuals who self-reported being Asian (Bangladeshi, Chinese, Indian, Pakistani) or from a non-Black Minority Ethnic (NBME) group due to small individual sample sizes. Patients were asked to complete a questionnaire which included demographic information upon admission into the hospital, if they wished to do so. Data on patients' race was taken from this.

All other data, including endodontic outcome determined by CBCT, pre-operative presence of a sinus tract, pre-operative presence of pain, swelling, obturation length and intra-operative root perforation, were available, as they had already been collected in the selected studies (Fig. 1).

Both primary root canal treatments and re-treatments were completed in one visit, or two visits with an interappointment calcium hydroxide medication using a standardised protocol7,23,24,25 (see online Supplementary Information), consistent with European Society of Endodontology guidelines,29 or an additional enhanced infection protocol.24 Operative procedures were undertaken by 35 endodontic residents, of which 14 were white and 21 were Asian or from a minority ethnic group, under the direct supervision of specialist endodontic staff at Guy's and St Thomas' NHS Foundation Trust, London, UK. None of the operators were Black (no Black endodontic resident was attending the programme). All received appropriate training and standardisation before the start of the studies. Where indicated, teeth were restored with cuspal coverage restorations within one month of the completion of the root canal treatment by the endodontic residents7 or by the referring dentists.23,24,25

Patients were recalled 12 months after the completion of the treatment. Treatment outcome in this review was determined based on the clinical and CBCT radiographic findings only7,23,24,25 (see online Supplementary Information and Table 4).

The influence of patients' race on the outcome of the treatment was the primary variable of the research. The aforementioned recorded variables were also analysed, including: sex and race of the operator and patient; the likely SES of the patient based on IMD scores; patient medical history; root length; root curvature; pre-operative presence of a sinus tract; pre-operative presence of pain; swelling; intra-operative root perforation; and obturation length. Root canal anatomy (including curvature) and quality of the root canal treatments (length and presence or absence of voids) were measured at root-level; the highest value of tooth curvature was extrapolated at tooth-level.

Statistical analysis included the description of categorical (absolute and relative frequencies) and continuous variables (mean, standard deviation, range and median) for the total sample, differentiating by outcome (favourable/unfavourable). Simple binary logistic regression models were performed to study probability of failure according to independent variables. Non-adjusted odds ratio (OR) and 95% confidence intervals (CI) were obtained. Relevant variables (p

A multiple regression model was conducted to analyse the outcome and the four independent variables: race, presence of a pre-operative lesion, short root canal filling and perforation (Table 5). Black patients showed a twofold increased risk of an unfavourable outcome (OR = 2.28; p=0.05) while NBME patients had a three times higher risk (OR = 3.07; p = 0.008) compared to white patients. The presence of a pre-operative radiolucency, short root canal filling and intra-operative perforation remained as significantly bad prognostic factors.

Further analysis was carried out to describe all the variables according to the race categories in order to look at the association of race with the clinical status of the tooth and patients profile (see Table 5 and online Supplementary Information). Socioeconomic status was associated with race (p

The failure rates shown in this study (21.3%) are similar to those of other CBCT outcome studies on the outcome of root canal treatments.6 In agreement with previous literature, root canal fillings which were short in length, the presence of a pre-operative lesion and the occurrence of intra-operative perforations were associated with a significantly higher chance of an unfavourable outcome.

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