Tackling geographic barriers to primary dental care (dental deserts): a systematic review

Search strategy results

The initial search yielded 6,704 results. After deduplication, 5,501 papers underwent title and abstract screening (Fig. 2). This identified 89 papers for full-text review, one of which was not accessible via the library services; therefore, 88 full texts were reviewed against the eligibility criteria, resulting in an initial 26 papers for inclusion.

Subsequent citation searching of these papers identified an additional 75 papers, of which 11 were duplicates. Title and abstract screening of these 64 papers indicated 36 full texts for review, of which a further 11 met the inclusion criteria. Thus, in total, 37 papers from 33 programmes were included in this review (with up to four papers per programme), where 33 reported primary research and four were reviews, and one of which was an update on another; thus, only the latter was included (online Supplementary Table 1).

Paper characteristics

Evidence was included from 26 countries, the most common being: the United States of America (n = 16 papers), Australia (n = 16 papers) and Canada (n = 5 papers), followed by the UK and India (n = 3 papers each) and the remainder having 1-2 papers. One paper reported including studies from Africa, Latin America and South East Asia but did not specify in which countries.

Of studies reporting on individual countries, 16 were HICs, five upper-middle (UMICs), four lower-middle (LMICs) and one low-income country (LIC).²⁸ Nine papers reported on a single initiative, while ten papers presented evidence on two to three initiatives and 13 papers provided evidence on four or more initiatives.

Quality appraisal results

The MMAT²⁵ was used for 32 papers, and five (four reviews, one economic analysis of a dental student clinic which reported evidence on access) were more appropriately assessed using the JBI review or economic analysis checklists.²⁶^,²⁷ Most included papers (n = 25) were regarded as being of high methodological quality and only four papers were of low quality (online Supplementary Table 1).

Themes identified

Online Supplementary Table 1 present a summary of the papers included within this review. Figure 3 demonstrates the complex associations between these papers and the identified themes. The distribution of the papers’ citations around the diagram’s circumference illustrates the multi-theme impact of the range of initiatives.

Four themes emerged while undertaking full-text reviews and data extraction, with sub-topics:

Workforce initiatives – including dental team skill mix, non-dental personnel, recruitment strategies and retention strategies
Out-reach initiatives – including teledentistry programmes, mobile clinics, school-based clinics, establishing new community clinics and outreach camps
In-reach initiatives – involving bringing patients to dental school clinics
Auxiliary access initiatives – affordability of care, engagement of local communities, cost-effectiveness of interventions, and remuneration of clinicians. Cost-effectiveness describes the value of an output related to the expenditure, as opposed to cost-efficiency which describes the use of available resources to provide services.²⁹

A total of 12 papers presented evidence within one theme only, whereas 14 provided evidence across two themes. Nine provided evidence spanning three themes and just two papers spanned all four themes as outlined below.

Workforce initiatives

Workforce initiatives had most evidence comprising using dental team skill mix and non-dental personnel, together with recruitment and retention of dental personnel.

Dental team skill mix

A total of 13 papers.³⁰^,³¹^,³²^,³³^,³⁴^,³⁵^,³⁶^,³⁷^,³⁸^,³⁹^,⁴⁰^,⁴¹^,⁴² Evidence presented by studies into dental team skill mix came from predominantly HICs (n = 11) with an even split between remote and rural settings and one virtual setting.³¹ Evidence came from more regional initiatives than local (n = 9; cf n = 5). Overall, 103,759 patients (range: 47-‘>33,500′)³⁰^,³⁵ were reported in the research in this sub-theme and the included workforce consisted of 77 dentists, 83 dental therapists, 43 dental hygienists and ten dental hygiene students.

Using a job role between the scope of the dental nurse and the dentist (referred to by a wide range of job titles but hereafter referred to as mid-level providers for continuity), all 13 studies provided evidence that delegation of tasks within these providers’ scope of practice has positive effects on clinical productivity and workload management at no detriment to quality of patient care. Outcomes varied between papers, with improved access reported between 17.0-39.3%,³⁰^,³²^,³⁹ workload markers showing a reduction of 3.27-3.50% for dentists³⁴ and management of 87.5-98.1% of clinical procedures by dental team skill mix.³⁶

Non-dental personnel

A total of five papers.³⁹^,⁴³^,⁴⁴^,⁴⁵^,⁴⁶ Evidence for non-dental personnel came predominantly from rural initiatives (n = 5) in three HICs and one LMIC, and a multinational review of evidence, primarily from HICs.⁴⁵ Evidence in this sub-theme came predominantly from regional (n = 4) rather than local (n = 2) initiatives. A total of 1,522 (range: 52-1,094)⁴³^,⁴⁶ patients were included in the evidence for this sub-theme.

Colleagues external to the dental team who were shown to improve access to dental care included: Cameroonian traditional healers (who screened and signposted patients to dental services);⁴³ members of the local community employed in non-clinical roles in dental services; and teachers identifying and signposting students in need of care to dental facilities.⁴⁵^,⁴⁶ All traditional healers could identify caries, periodontal diseases and candidiasis three months after a short training course⁴³ and this was the only paper from a LMIC in this theme.

Community members contributing to dental care were common in Australian initiatives providing care for Aboriginal and Torres Strait Islander populations (where cultural competence is paramount to ensuring accessibility) as Aboriginal health workers. Two papers reported teachers were responsible for prioritising children at higher need of treatment,⁴⁵^,⁴⁶ whom they identified ‘excellently’ according to the authors of one initiative,⁴⁶ 57.4% of whose participants had never previously visited a dentist.

Recruitment

A total of 17 papers.³³^,³⁴^,³⁵^,³⁶^,⁴¹^,⁴²^,⁴⁵^,⁴⁷^,⁴⁸^,⁴⁹^,⁵⁰^,⁵¹^,⁵²^,⁵³^,⁵⁴^,⁵⁵^,⁵⁶ Evidence on recruitment came predominantly from rural (n = 15) studies comprising local (n = 9) and regional (n = 8) initiatives. Because the majority of evidence came from Australian studies, 14 papers were from HICs with additional multinational reviews (n = 4) from predominantly HICs. Evidence under this subtheme comprised studies reporting 49,832 patients (range: 47-27,459),³⁴^,³⁵ 1,387 dentists, 80 dental therapists, ten dental students and ten student dental care professionals.

All primary research into recruitment was conducted in Australia. Recent papers reported a stronger link between both students’ rurality of origin and experience of clinical placements in areas with access barriers to increasing recruitment within these areas.⁴⁸^,⁴⁹^,⁵⁰ Among papers which reported on a novel rural recruitment scheme,⁴⁸^,⁴⁹^,⁵⁰ there was an increased rural recruitment rate of between 15.0-28.4% among students who had completed a rural clinical placement. Placement length was identified as a key factor in rural recruitment but the literature did not confirm an ideal placement length. All but one paper suggested that rural placements increase the likelihood of future rural employment; however, one outlier⁴⁷ reported that these placements can also dissuade or reinforce negative views of rural work among students.

Retention

A total of seven papers.⁴²^,⁴⁸^,⁵⁰^,⁵²^,⁵⁴^,⁵⁵^,⁵⁶ Evidence on retention came from more rural (n = 7) than remote (n = 2) interventions. It comprised local (n = 4), regional (n = 2), state (n = 2) and national (n = 1) initiatives from HICs or multinational reviews including predominantly HICs. This evidence focused on 1,185 dentists.

Results are less clear on effective retention strategies from most papers in this review, aside from targeted recruitment from underserved areas into dental education. Almost all papers encourage further research into specific retention strategies. Initiatives included: financial incentives⁴⁷^,⁴⁹^,⁵⁵ (employers’ student loan repayment incentives, bundled interventions combining multiple smaller financial initiatives); clinical exposure⁴³^,⁴⁵^,⁵¹ (dental student placements, rurally located training facilities); compulsory service⁴²^,⁵⁴ (bonding schemes); and ongoing support⁴²^,⁵⁴ (professional support, continual education opportunities).

Outreach initiatives

Conventional outreach programmes were investigated for more resource-effective alternatives. Teledentistry was a common theme in the included papers and represents a potential platform to deliver and facilitate outreach services.

Teledentistry

A total of seven papers.³⁰^,³¹^,³²^,³⁸^,⁴²^,⁴⁵^,⁵⁷ Evidence on teledentistry was spread evenly between remote (n = 4) and rural (n = 5), and local (n = 5) and regional (n = 4) initiatives. Five studies presenting evidence from initiatives in HICs, and two reviews considering predominantly HICs, were included. Evidence came from studies reporting 42,936 patients (range: 296-‘>35,000′),³⁰^,³² one dentist, three dental therapists, 42 dental hygienists and ten dental hygiene students.

Despite variable outcome measures, all papers reported high levels of satisfaction from patients and clinicians, as well as affordable and clinically reliable improved access to dental care. Four of the papers suggested that teledentistry improved access,³¹^,³⁸^,⁴⁵^,⁵⁷ and the others demonstrated 17% improved service engagement³⁰ and referral of patients with additional care needs (12.2% of study population) to dentists.³² Also demonstrated is the ability to deprioritise patients with no detected healthcare needs so follow-up access efforts can be focused on people most in need. The workforce educational capacity of teledentistry provided support for clinicians in training and clinical care provision.⁴²

Teledentistry was applied to screening, diagnosis, consultation, treatment planning, mentoring and access to care in a cost-effective and mutually acceptable way for patients and clinicians, but with limits on what treatment could be delivered.

Mobile clinics

A total of five papers.³⁰^,⁴⁶^,⁵⁸^,⁵⁹^,⁶⁰ Rural initiatives (n = 5) were reported more commonly than remote (n = 2), and those at a regional scale (n = 5) were more frequent than local (n = 1). Three HICs’ and two LMICs’ initiatives were included. Mobile clinics provided care to a reported 49,629 patients (range: 215-‘>33,500′).³⁰^,⁵⁸

These demonstrated effective delivery of vital healthcare services, typically providing emergency and simple conservative care to target populations. Some studies reported directly on improved access, showing 628 patients of 1,094 seen by the service (57%) had never seen a dentist before,⁴⁶ or providing dental care to 739 patients in hard-to-reach areas.⁶⁰ Mobile clinics were found to improve access to care to all communities within the literature; although, service provision varied: common treatments included examinations, scaling, direct restorations, and extractions, but the provision of preventive care varied from none to little.

Outreach camps

A total of five papers.⁴²^,⁴⁴^,⁴⁵^,⁶¹^,⁶² Evidence from five rural and two remote initiatives were included in this subtheme, with three being enacted at regional level and two locally. One HIC presented evidence on outreach camps, two LMICs, and two reviews of evidence primarily from HICs. Evidence on outreach camps reported on 24,353 patients (range: 1,371-22,982).⁶¹^,⁶²

Outreach camps were shown to positively impact access to oral healthcare: one improved access for 22,982 patients over a two-year period,⁶¹ including providing travel for residents of surrounding villages. A similar model brought dental care to 1,371 patients in rural India.⁶² Another outreach model involved seasonal dental team visits⁴⁴ to remote areas of Australia, delivering 1,608.19 dental weighted activity units (equivalent to 17,690 comprehensive examinations) to remote Australian communities in the two-year study period. A review of university based initiatives⁴⁵ reported that outreach programmes were capable of addressing rural populations’ dental healthcare needs, at least to the extent of a population’s perceived need. Outreach camps were also shown to be a beneficial educational environment for healthcare students which led to increased likelihood of future rural employment;⁴² however, this evidence was generic. While it was not possible to extract dental data, there was no evidence that the pattern for this discipline did not follow the general trend.

School-based clinics

A total of three papers.³¹^,³⁹^,⁴⁰ School-based clinics were more often regional (n = 2) and rural (n = 2) initiatives than local (n = 1) or remote (n = 1). All evidence on the effect of school-based clinics on access to dental care came from HICs. Some 15,077 patients (range: 376-13,070)³⁹^,⁴⁰ had improved access to care with the use of school-based clinics.

All studies in this theme used skill mix, with one³¹ also using teledentistry with an uptake rate of between 70−99.4%.⁴⁰ School-based clinics reported more reliable levels of prevention than outreach or mobile programmes which provided more curative than preventive services.

Establishing new community clinics

A total of four papers.³³^,³⁴^,³⁵^,⁴⁴ Local and regional initiatives were both the subject of two papers each, but there was more evidence from remote (n = 3) than rural (n = 1) areas. All studies in this sub-theme were from HICs. From studies which reported on this data, 49,832 patients (range: 47-27,459),³⁴^,³⁵ 72 dentists and 23 dental therapists participated in establishing new community clinics.

Establishment of new community clinics in the Yukon-Kuskokwim Delta region of Alaska, combined with dental team skill mix, brought dental care to 27,459 residents.³⁴ Australia’s research⁴⁴ produced evidence that establishing a new rural community clinic facilitated providing almost twice as much care than flying in external clinicians (3,072.16 versus 1,608.19 dental weighted activity units in the same study’s outreach services) for approximately half the cost in the same time period, and additionally used non-dental personnel by employing local Aboriginal community members in managerial roles, engaging the local community.

In-reach initiatives

This theme only involved dental school clinics; although, the initiative reported two impacts: meeting patients’ needs (clinical service provision) and improving students’ clinical exposure in rural settings (workforce provision).

Dental school clinics

A total of 14 papers.⁴²^,⁴⁵^,⁴⁶^,⁴⁷^,⁴⁸^,⁴⁹^,⁵⁰^,⁵¹^,⁵²^,⁵³^,⁵⁶^,⁶³^,⁶⁴^,⁶⁵ Due to the nature of dental school clinics, there were more local than regional initiatives (n = 9; cf n = 5), and more were rural than remote (n = 13; cf n = 5). All evidence came from HICs or multinational reviews presenting evidence predominantly from HICs. Studies which presented patient and workforce data showed collective care of 49,302 patients (range: 1,094-43,128),⁴⁶^,⁶³ involving 1,440 newly graduated dentists, 502 dental, 79 dental hygiene and 23 dental therapy students.

Clinical service provision improved access for 49,302 patients, with study periods spanning one academic year (September 1971 to July 1972)⁴⁶ up to three years.⁶³^,⁶⁵ Within workforce provision, rural clinical placements were identified by all studies as important factors in students’ future decisions to work rurally. Australian studies on dental school rural clinical placements and likelihood of continuing to work in similar locations after graduation⁴⁸^,⁴⁹^,⁵⁰^,⁵⁶ reported a 17-18% rural employment rate for those who had not experienced a rural placement and a 33.0-44.8% rural employment rate for those who had: an increase of between 15.0-27.8%. A longitudinal report of workforce provision from dental school clinics showed a 5.0-38.9% (mean: 13.7%) rural employment rate for those who had not undertaken a rural placement and a 10.9-31.5% (mean: 21.82%) rural employment rate for those who had done so.⁵⁶

Auxiliary access initiatives

Initiatives which were reported as supporting interventions under the other themes (workforce, outreach, in-reach) were termed ‘auxiliary’ access initiatives to reflect their supportive role. These include local community engagement, consideration of affordability of care, cost effectiveness and clinician remuneration.

Engage local community

A total of seven papers.³³^,³⁴^,³⁵^,³⁹^,⁴³^,⁴⁴^,⁶⁴ Evidence on engagement with the relevant local community was presented in seven papers and refers to acknowledging and respecting cultural needs of societies and developing new services alongside these needs, with evidence of co-producing solutions. With an equal number of rural and remote initiatives (n = 4), five initiatives were at regional scale and three were local. Evidence from one LMIC was included in this sub-theme and six papers from HICs. A total of 63,462 patients (range: 47-27,459)³⁴^,³⁵ were reported within the literature, alongside 72 dentists, 23 dental therapists and 57 dental students. External to the dental team, 19 healthcare workers and 19 community members were also included in the evidence for this sub-theme.

In Alaska, communities responded to and accepted their members in positions of clinical responsibility (improving satisfaction with programmes) because they had an ‘innate understanding of cultural norms’,³⁵ and represented timely access to care.

Cameroonians spent, on average, 7% of household income (regardless of gross income) on traditional medicine,⁴³ and traditional healers provided healthcare tailored to both the health and spiritual needs of their clients, thus there is a cultural value to this group of personnel. Similarly, the Australian Aboriginal and Torres Strait Islander community has prevalent social and cultural needs which were repeatedly shown to be satisfied when Aboriginal leaders were consulted during service design and an Aboriginal health worker included in the staffing of any resultant service.³⁹

Affordability of care

A total of one paper.⁴³ Evidence surrounding affordability of care came from a LMIC with the regional initiative taking place in a rural area of Cameroon. The paper reported on 52 patients and 21 traditional healers.

This paper suggested that substantially more affordable care provided by traditional healers in Cameroon attracted those experiencing dental complaints to their services.⁴³ Therefore, an initiative in which traditional healers were trained to identify oral pathologies and refer to conventional health services where appropriate was established. Affordability was also considered in this paper as a reflection of distance from, and therefore potential cost to travel to, oral health services: 76% of patients were reported as living within a 30-minute radius of a traditional healer, but only 3.9% of patients being within a 30-minute radius of an oral healthcare facility.

Cost-effectiveness

A total of five papers.³⁸^,⁴⁰^,⁴⁴^,⁴⁵^,⁶⁴ Cost-effectiveness considerations had evidence presented from three regional and two local initiatives. These were predominantly remote (n = 4); although, rural (n = 2) and virtual (n = 1) initiatives were identified. Evidence came from HICs or reviews of evidence predominantly from HICs. There were 16,272 patients (range: 3,202-13,070)⁴⁰^,⁶⁴ included in this sub-theme, with one dentist, three dental therapists, two dental hygienists and 57 dental students reported across initiatives.

Dental team skill mix was shown to be cost-effective, with mid-level providers (dental therapists) typically exceeding their costs of employment in revenue (by up to $216,000 USD),³⁸ or contributing at least 50% to their costs in areas with the poorest remuneration on public healthcare systems.³⁸ School-based clinics and establishing new community clinics were both shown to be cost-effective compared to conventional private dental care and existing outreach programmes, respectively. University-level initiatives and student clinics struggled to demonstrate complete cost-effectiveness; however, income generated approached 50% of the running costs of these services.⁴⁵^,⁶⁴

Remuneration of clinicians

A total of four papers.⁴²^,⁵⁵^,⁵⁷^,⁶⁶ Evidence on remuneration predominantly originated from rural initiatives (n = 3); although, one remote and one virtual initiative also provided evidence. The scale of initiatives was broad, with one local, one regional and one at state level. All evidence came from HICs or multinational reviews presenting evidence predominantly from HICs and reported on 4,721 patients (range: 431-4,290)⁵⁷^,⁶⁶ and 43 dentists.

All four papers suggested that acceptable remuneration encourages clinicians to engage with programmes. This was identified as a key factor in the success of two programmes: encouraging increased prevention and integrating teledentistry into clinics.⁵⁷^,⁶⁶ Salaries and allowances have been demonstrated as key factors of clinicians’ decisions to work rurally.⁴² Additionally, loan repayment programmes have shown influence on retention of rural health workers, with over half of providers remaining in a rural community in one study,⁵⁵ and of those who had left, one-third had stayed five years or longer in their rural community after completing their period of obliged service.

Alignment with The Lancet’s ‘High-quality health systems framework’

The distribution of evidence across domains allowed us to consider the components of the ‘foundations’ domain individually. While the ‘processes of care’ and ‘quality impacts’ domains also contain separate components, the evidence did not readily differentiate into these sub-categories. Therefore, the components of the ‘foundations’ domain were considered individually, but the other domains were addressed without further subdivision.

Interventions in all 37 papers aligned with the ‘foundations’ domain of the high-quality framework,²² particularly the ‘platforms’ (n = 28 papers) and ‘workforce’ (n = 27 papers) components. Most (n = 30) papers addressed ‘quality impacts’ and under half (n = 15) considered ‘processes of care’.

When aligning the interventions within each paper to the framework, the complex web of effects is demonstrated (see online Supplementary Table 2). Only three papers reported on interventions within just one domain (‘foundations’). A further 23 reported interventions that spanned two domains – ‘foundations’ and ‘quality impacts’ (n = 19) and ‘foundations’ and ‘processes of care’ (n = 4) – and the remaining 11 covered all three. Considering the separate components under ‘foundations’ alongside ‘processes of care’ and ‘quality impacts’, all papers addressed at least two components, and two reported on interventions within all five components of the ‘foundations’ domain, as well as the two other domains.⁴²^,⁵⁷

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