Introduction

Crucial to the effective and efficient delivery of healthcare is the time taken to undertake a given procedure. Time is as they say, money. Primary dental care involves the delivery of a large range of distinct procedures and knowledge of the time taken per procedure is important in determining the economics of making a dental practice function. There have been relatively few studies undertaken in the United Kingdom into the time taken to deliver dental care [1, 2]. The most commonly cited study is work undertaken by the British Dental Association known as “The 1999 Heathrow timings inquiry” [1]. This work took the form of a consensus exercise undertaken by 21 general dental practitioners.

However, since this work in the late 1990s there have been many developments in the delivery of primary dental care. These include changes in patient complexity – improved oral health in younger people, is counterbalanced by an ageing population with more complex oral care needs both in terms of the dental care required and presenting co-morbidities [3,4,5]. Whilst there have been efforts to produce contemporaneous timing of common dental procedures, these have had small sample sizes or only collected data about a limited number of procedures [2, 6].

In England and Wales, a major objective of reforms to the state-funded dental system (National Health Service [NHS]) is to transition the delivery of dental care from a system focused on restoration to one whose focus is on prevention [7,8,9]. Scotland and Northern Ireland have retained to a greater extent the fee-per-item system of funding that was abandoned in England and Wales in 2006. It is also the case that a desire to see greater use of skill-mix and a team where dentists undertake higher-skill procedures (e.g., crowns and bridges) and more routine procedures (e.g., restorations, fissure sealants, oral hygiene instruction) and are delegated to dental therapists, dental hygienists and dental nurses, is a long standing goal of system reform [10,11,12,13,14,15].

It is therefore timely to provide up-to-date data timings in contemporary dental practice.

Aims and objectives

The study was designed to investigate, as estimated by dental professionals, the time taken to undertake a range of common, contemporary procedures in general dental practice. A comparison with previous estimates was also undertaken.

The context of the work was NHS general dental practice in Wales and the specific objective was to measure the estimated range and central tendency of the time taken by dentists, dental therapists, dental hygienists and dental nurses to carry out commonly performed dental procedures.

Materials and methods

Data collection

Data were collected by an online questionnaire (onlinesurveys.ac.uk). A common landing page was presented to all study participants which posed questions on role (dentist, dental hygienist/dental therapist, dental nurse, time since qualification, whether their primary dental qualification was awarded in the United Kingdom (UK) or from a non-UK institution, and whether they were registered as a specialist with the General Dental Council (the regulatory body for dental professionals in the UK).

Participants were also asked whether they worked in NHS general dental practice and what proportion of their time was devoted to NHS (as opposed to private) practice. Participants who indicated that they did not work in NHS general dental practice were thanked for their time and excluded from any further participation in data collection. Those who were engaged in NHS general dental practice were then, using skip logic, dependant on their role (dentist, hygienist/therapist, nurse), directed to a series of questions in which they were required to estimate the mean time, minimum and maximum time required to undertake procedures on 95% of occasions. Participants were requested to assume that they carried out all the procedures themselves, and to calculate the average timings by including the time required for the patient to enter the surgery, administration of local anaesthetic, performing the task, and patient departure from the surgery. A task was defined as one treatment item regardless of whether it was performed in one or more appointments.

The list of procedures was derived from the NHS Business services Authority General Clinical Data Set [16] and informed by the clinical experience of the investigators and were divided into procedures involving children and those involving adults.

The questionnaire was administered between 0ctober 2020 to January 2021. Participants were specifically asked to provide their estimates based on their experience prior to the COVID-19 pandemic.

Questions on time taken for inhalation sedation and IV sedation were answered by just a few respondents and these data were removed from the analysis.

Study population

The study sample frame comprised all dental professionals working in Wales whose details were included on a database held by Health Education and Improvement Wales (HEIW). This organisation is responsible for the delivery of postgraduate education and training for continuous professional development for all dental professionals in Wales and the majority of dentists, dental hygienists, dental therapists and dental nurses in the country are registered with HEIW. An invitation was sent to all on the database with a covering letter explaining the purpose of the work and a link to the online survey. A reminder email was sent after 2 weeks.

Data analysis

Descriptive analysis of the timings of common dental activities from the questionnaires (mean; range; % non-response) were performed separately for child and adult patients, for dentists, dental therapists/dental hygienists, and dental nurses, and compared. Wilcoxon signed rank tests were used to determine the significance of differences between estimated times for undertaking between dentists and hygienists/therapists. Analyses were undertaken in SPSS (IBM SPSS Statistics v27). Significance level was set at 0.05.

Sample size determination

The sample size calculation was based on estimating the length of an adult dental examination, the most commonly performed dental procedure in NHS Wales. In the 1999 BDA Heathrow Timing Inquiry the mean length of a dental examination was 11.3 min, with a SD of 2.31 min.

Therefore, to estimate the mean time for a dental examination within a margin of ± 1 min with a 95% confidence level, 20 estimates per role, were required. We analysed the data for all those who responded to the survey.

Results

The demographic characteristics of the survey respondents are shown in Table 1. In total 41 dentists, 21 dental hygienist/therapists and 34 nurses completed the survey, the mean time qualified being 18.4, 13.8 and 17.8 years for these professional groups respectively. The proportion of patients treated via the NHS by dentists was 78.3%.

Table 1 Demographics of the respondents to the survey
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The estimated time taken to complete clinical procedures by dentists for adult and child patients are illustrated in Tables 2 and 3.

Table 2 Mean time taken to undertake clinical procedures in adult patients as estimated by dentists
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Table 3 Mean time taken to undertake clinical procedures in child patients as estimated by dentists
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The estimated time taken to complete clinical procedures by dentists for adult and child patients compared with dental hygienists and therapists are illustrated in Figs. 1 and 2. Estimated times for adult patients were broadly similar and not statistically significantly different. The greatest difference occurred in the case of scale and polish where dentists said that this on average took 8.8 min compared with the dental hygienists and therapists whose estimate was almost double at 16.4 min. However, for six-point pocket charting (10.2 vs. 9.1), supra and subgingival scaling (20.8 vs. 19.6) and root surface debridement (30.1 vs. 28) dentists estimated marginally more time than the hygienists and therapists.

Fig. 1
figure 1

Mean time taken to undertake clinical procedures in adult patients as estimated by dentists and dental hygienists/dental therapists

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Fig. 2
figure 2

Mean time taken to undertake clinical procedures in child patients as estimated by dentists and dental hygienists/dental therapists

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In the case of child treatments, overall the hygienists and therapists estimated that they spent a significantly greater period of time (p = 0.04) than did dentists undertaking similar procedures. For example they suggested more than twice the time required to undertake a scale and polish (12 min) compared with the dentists (5.3 min). Hygienists and therapists estimated a greater time to complete all other procedures except in the case of clinical note taking where they suggested this required 4.9 min compared with the mean of 5.8 min reported by dentists.

The time taken by dental nurses to undertake the various tasks that fall within their scope of practice are recorded in Supplementary Table A1.

A complete presentation of clinical timings as estimated by dentists, hygienists/therapists and dental nurses are presented in supplementary Tables A1-A3.

A complete comparison between the two previous studies [1, 2] and this one is not possible as different procedures were enquired after. For those procedures where direct comparison is possible the results are displayed in Fig. 3. From this it is apparent that the mean estimated time per procedure differed somewhat across the three studies, with the time taken to construct upper and lower acrylic dentures demonstrating the greatest variation.

Fig. 3
figure 3

Comparison of time taken present study, Bearbe et al. 1999 (Heathrow study) and Ganbavale et al. (2019) studies as estimated by dentists

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Discussion

This work provides contemporaneous estimated times taken to undertake routine dental procedures in NHS general dental practice, updating the often quoted “Heathrow Study” [1] and a more recent estimation by Ganbavale and colleagues [2]. The results here which focus on Wales, may not necessarily apply elsewhere in the United Kingdom.

The use of skill-mix as a means of delivering a dental care system with a greater emphasis on prevention has been described extensively [10,11,12,13, 15]. This work establishes differences in the perceived time taken by different members of the team to complete the same task. In the case of adult patients, the finding that there was no significant difference between the time taken by dentists and dental hygienists/therapists lends weight to the concept of delegating preventive and more simple restorative care to the dental hygienists and dental therapists. In contrast, why the dental hygienists and dental therapists took longer to undertake all procedures in children, except for clinical note writing, is unclear. These data suggest that in delegating care to dental hygienists and therapists there are unlikely to be savings in terms of time. They may also reflect that most dental therapist and hygienists in the UK are currently employed to provide periodontal treatment for adults rather than being able to provide full range of treatment within their scope of practice [17]. Similarly. comparing the cost of providing treatment items by dentists versus therapists and hygienists was not within the scope of this study. However, the difference in hourly rate/salary of dentists and dental therapist-hygienists may mean cost savings for employers provided that there are no barriers for using the full skill-set of therapists and hygienists.

There are limitations to the work that are worth mentioning. The times reported are estimates and the sample is purposive. The database to which invitations to participate were sent contained 3,869 individuals. This included all dental professionals registered with Health Education and Improvement Wales and included those working in the community and hospital dental services. It is therefore not possible to determine a response rate to the survey due to the lack of an accurate denominator. The sample size calculation suggested that a minimum of 20 participants per professional group was required. In our analysis we included all those who responded. It is accepted that there is likely an element of response bias in this approach. However, the methodology and sample size used in this study are similar to that of the original study on which the current timings for NHS dentistry have been based for more than two decades.

The estimates of how much time was spent on each item was when working under the NHS system should not be taken as the recommended time. It is also the case that time spent does not necessarily directly correlate to quality of care but is of course somewhat linked.

Of note is the relatively short times being reported to undertake root canal treatments. This likely reflects the pressures for undertaking these treatments in NHS practice. A limitation of how this was recorded means that it is not clear on whether this also is interpreted as including the time for undertaking the definitive restoration after completion of the endodontic treatment.

Use of these data and future research

The data provided here will act as a useful resource for service planners and managers in developing and commissioning future dental services, particularly a service which envisages a greater degree of skill-mix and of preventive care. There is scope for further work to examine the differences in times estimated by different professional groups and to model how this might impact on a revised model of dental care delivery in the future.

Conclusions

This work provides contemporary timings for commonly performed dental procedures in NHS general dental practice as undertaken by different members of the dental team. They may be helpful in designing a service to address current access issues. The reported time taken by dental hygienists and therapists suggest that they are similar to dentists when treating adults but take more time when treating children.