Oral diseases remain a major global public health challenge, affecting an estimated 3.5 billion people and limiting daily functions such as eating, speaking, and social participation. Beyond the clinical burden, they impose substantial economic losses through direct treatment expenditures and productivity impacts, with the heaviest consequences often borne by disadvantaged populations.^[1] Despite growing global consensus that essential oral health services should be integrated into primary health care (PHC) as part of universal health coverage, translation from policy aspiration to routine frontline delivery remains uncertain in many settings, particularly in low- and middle-income countries (LMICs).^[2] A practical way to assess whether integration is happening is to examine the service mix delivered at PHC level - specifically, whether preventive interventions expand over time or whether care continues to be dominated by curative, late-stage procedures. However, the evidence base remains limited in one critical respect: longitudinal, facility-level descriptions of preventive-versus-curative service patterns under PHC-oriented reforms are scarce, and much of what is known comes from cross-sectional snapshots.^[3,4] Routine electronic health records (EHRs) and routine health information systems offer a feasible methodological solution because they capture service activity continuously and can track trends at scale.^[5] Within this framing, Iran can be treated not as the topic of primary interest, but as an illustrative case through which transferable lessons can be generated about monitoring PHC-based oral health delivery under reform conditions.^[2,6]

Iran provides a relevant case because it combines a high burden of oral disease with well-documented structural barriers to equitable access. Longitudinal estimates indicate that the mean decayed, missing, and filled teeth (DMFT) index increased significantly between 1990 and 2017 specifically in young adults.^[7] Historically, dental care in Iran has been shaped by high out-of-pocket spending, limited financial protection, and the uneven geographic distribution of dentists - conditions that tend to concentrate services in urban areas and disadvantage rural and semiurban communities.^[8] In such contexts, oral health inequities are not only a matter of individual risk; they reflect health system design, financing arrangements, and the availability of prevention-oriented care within PHC.^[8,9] This is precisely the type of systems problem that global policy documents increasingly emphasize: reducing avoidable disease by shifting emphasis from downstream treatment toward upstream prevention, early detection, and continuity of care delivered close to where people live.^[10]

In response to broader health system challenges, Iran implemented a nationwide reform agenda in the mid-2010s aimed at improving access and quality within the public sector. Within this broader reform environment, oral health initiatives were developed to strengthen the delivery of essential dental services through the PHC network.^[2,3] The family dentist program represents one operational model aligned with this direction. It is designed to reach rural and semiurban populations and to prioritize groups with elevated need, including children and maternal populations. The program package emphasizes preventive interventions (such as fluoride varnish and fissure sealants) alongside basic curative services (for example, restorations and extractions) delivered within PHC-affiliated settings.^[6]

However, policy design and service delivery frequently diverge. Even when reforms lower financial barriers or expand entitlements, utilization may remain shaped by perceived need - often meaning pain-driven visits and delayed care - rather than routine prevention.^[9] Moreover, implementation constraints common to PHC delivery platforms can undermine intended shifts in practice: workforce instability, infrastructure limitations, and operational disruptions can all affect the quality of the services.^[2] In this respect, the key question for an international readership is not the fine detail of Iran’s institutional arrangements, but the broader, generalizable problem of oral health integration into PHC settings.^[4,10]

Answering that question requires longitudinal evidence. A single-year or cross-sectional evaluation can describe coverage at one point in time, but it cannot show whether service patterns are evolving toward prevention, whether changes are sustained, or whether a temporary increase reflects short-lived implementation pressure rather than durable system change.^[11] In PHC-based oral health programs, the preventive-versus-curative balance is a particularly informative operational signal because it captures the everyday clinical output of the system: preventive services imply proactive outreach, planned encounters, and early-stage management, whereas a predominantly curative profile - especially extraction-heavy patterns - often signals late presentation and limited prevention. Tracking this balance over multiple years, therefore, provides a pragmatic lens on the policy-to-practice gap and on the extent to which prevention-oriented intent is realized in routine delivery.^[12]

Iran’s capacity for longitudinal monitoring is strengthened by the integrated health system (SIB), a national EHR platform used in public-sector primary care to record clinical encounters with standardized service codes.^[13] In routine practice, these records are not collected for research purposes; they are collected for service delivery and reporting. That feature is methodologically valuable: it reduces reliance on retrospective recall, enables multiyear trend analysis, and supports facility-level comparisons. In the context of PHC dental services, SIB records can therefore be used to describe how an oral health reform package is reflected in actual service activity over time.^[8]

Against this background, the present study aimed to describe 6-year trends in dental service utilization delivered through rural and semiurban PHC dental settings in Isfahan Province, from 2016 to 2021, using routinely collected SIB records. Dental services in this study refer to the nationally coded package of essential clinical dental services recorded within the PHC platform, encompassing both preventive interventions (including fluoride varnish and fissure sealants) and common curative procedures (including restorations and extractions). The descriptive analysis focuses on two complementary outcomes: (i) annual service volumes and (ii) the composition of care, with emphasis on the preventive-versus-curative balance. By examining these trends over time, the study provides an empirical assessment of whether real-world service delivery moved in the prevention-oriented direction that PHC-based oral health reforms typically intend. Importantly, the contribution is positioned as transferable learning: Iran is treated as an illustrative LMIC case in which routinely collected electronic records can be leveraged to monitor whether oral health integration into PHC changes what facilities deliver.

This 6-year longitudinal analysis of level 2 dental procedures delivered through Isfahan’s PHC network highlights four key findings: an extraction-dominated treatment profile, a preventive component that remained relatively low, a sharp pandemic-related disruption followed by partial recovery, and growing differences in the treatment profile between the two health center networks. Together, these findings show how policy priorities, provider incentives, and local context can shape routine dental care delivery.

A key finding was the notable gap between extractions and restorative care. Across 133,075 procedures, the extraction-to-restoration ratio was 2.8:1, indicating that extractions were far more common than restorations. This pattern contrasts with the program’s stated emphasis on preserving natural dentition.^[6] Similar extraction-dominant profiles have nevertheless been reported in other public systems. For example, Bhayat et al., in a review of PHC dental facilities in South Africa, reported extraction-to-restoration ratios substantially higher than those observed in Isfahan. Such differences may reflect variation in access to restorative materials and equipment, and broader socioeconomic conditions across settings.^[14,15] In a scoping review of universal oral health coverage in 27 low-income countries, Luan et al. reported that extractions are commonly included in health benefit packages, whereas preventive interventions are less frequently available.^[15] International experience also indicates that improving the preservation of natural permanent teeth often requires coordinated, multisectoral efforts and integration of oral health into existing health programs.^[2,16] For example, Nzobo et al. evaluated a government-led reform of Tanzania’s national oral health system and reported a substantial improvement in the balance between tooth preservation and extraction over a 2-year period. The authors suggested that embedding oral health within primary care and maternal health services can achieve rapid improvements in preventive coverage and other short-term oral health outcomes.^[16]

The preventive share of dental procedures showed a distinct temporal pattern. Preventive procedures accounted for 21.8% of total workload in 2016, fell to 7.2% in 2017 (when overall workload peaked), then rebounded to 21.0% by 2019 and remained near 19%-21% in 2020-2021. The combination of a high workload and a low preventive share in 2017 may indicate that clinics prioritized unmet curative needs in the populations during a period of rapid service expansion in early years of implementing family dentist program. This pattern is consistent with findings reported by Watt et al. and the review by Gafari et al., which noted that in the early phases of oral health programs, high levels of unmet needs often shift dental procedures toward curative care rather than prevention. In such settings, procedures that address immediate pain and urgent complaints tend to take priority over preventive interventions.^[17,18]

There was a significant reduction in procedures delivered in 2020. This is consistent with international evidence. For example, the scoping review by Farrokhi et al. documented substantial reductions in dental service delivery during the COVID-19 pandemic across multiple settings, attributing these declines to both supply-side restrictions (e.g., service closures and capacity limits) and demand-side avoidance related to perceived aerosol-transmission risk.^[17] Notably, the preventive share in Isfahan remained relatively stable in 2020 (19.4%), which may indicate that low-aerosol preventive procedures (such as chair-side fluoride varnish) were more feasible to maintain under infection-control constraints. This pattern differs from findings in US federally qualified health centers, where Choi et al. reported a relative shift toward oral surgery and away from preventive care.^[19] Differences in program context may partly explain this contrast. The family dentist program was primarily implemented in rural and smaller-population settings, where pandemic-related disruptions may have been less severe than in large urban areas, potentially supporting a faster recovery.^[20] Consistent with this interpretation, the 84.5% increase in total workload in 2021 indicates a substantial recovery, although total workload remained 26.2% below the 2019 peak.

A policy-relevant finding is the sustained and widening difference between Center No. 1 and Center No. 2. Center No. 1 consistently delivered a higher preventive share, whereas Center No. 2’s preventive share declined to 4.3% by 2021 despite having the higher total workload. Several mechanisms may contribute. First, workforce capacity differed and per-provider workload was markedly higher in Center No. 2. Over 2016-2021, Center No. 2 delivered 76,697 procedures versus 56,378 in Center No. 1. On average, each provider delivered approximately 2,015 procedures per provider-year in Center No. 2 compared with 819 in Center No. 1. This imbalance was especially visible in high-volume curative work such as permanent tooth extraction (44,168 in Center No. 2 vs. 21,984 in Center No. 1). Sustained clinical pressure at the provider level can limit the delivery of preventive services and favor curative procedures.^[9] In addition, differences in accessibility and provider characteristics may influence the types of procedures delivered. Center No. 1 covers more geographically dispersed and less accessible facilities, which may be more likely to rely on recently graduated dentists completing mandatory service. In contrast, Center No. 2 serves more accessible areas that may be more attractive to experienced dentists. In a performance-based payment setting, more experienced and skilled clinicians may respond by prioritizing higher throughput curative procedures, which could result in favoring curative dental procedures. These behavioral responses are consistent with evidence from other health systems. For example, Jia et al. reported that provider behavior is sensitive to remuneration design, including time-weighting frameworks that assign higher value to procedures requiring more clinical time. This may encourage providers to prioritize more complex curative procedures over preventive services, which are often assigned to lower time weights and therefore generate lower returns.^[21,22] This observed workload imbalance has implications for service quality and workforce sustainability. Persistently high procedures-per-provider ratios may increase time pressure, reduce preventive delivery, and negatively affect provider satisfaction. Furthermore, unmeasured differences in social determinants of health may influence need and care-seeking. Although patient-level socioeconomic data were unavailable, Iranian studies such as Vali et al. and Javadzadeh et al. highlighted socioeconomic gradients in utilization and higher caries burden in rural children, consistent with wider evidence on oral health inequalities. These contextual factors could contribute to between-network differences in both absolute workload and the type of services delivered.^[23,24]

Despite the expansion of PHC-based dental delivery under the oral health reform in Isfahan, service delivery during 2016-2021 remained largely extraction-dominant, with restorative care occurring far less frequently. Preventive procedures formed a minority share overall and varied over time. The COVID-19 shock produced a sharp decline in 2020, followed by substantial recovery in 2021, indicating both vulnerability to external disruptions and the capacity for recovery within a state-supported PHC network. These findings provide a population-level longitudinal baseline for monitoring program performance and refining policy. Future work should move beyond description to test plausible mechanisms by linking changes in remuneration rules, time-weighting frameworks, staffing patterns, and characteristics to shifts in the treatments delivered. Such evidence would support targeted reforms - particularly recalibrating incentives and aligning workforce capacity with demand - to better balance throughput with the program’s longer-term goals of tooth retention and preventive care.