Early childhood caries (ECC) remains one of the most prevalent chronic diseases in children worldwide, affecting nearly 50% of preschool- aged children in some regions [1,2]. ECC is associated with pain, infection, impaired nutrition, and reduced quality of life [3,4]. Early detection enables preventive interventions and minimally invasive treatment, reducing disease burden and costs [5]. Visual-tactile dental examination is the current gold standard for ECC diagnosis, but it requires trained personnel, appropriate facilities, and infection control measures, which may limit reach in community settings [6]. Mobile technology, including smartphone-based intraoral photography, has emerged as a potential tele- dentistry tool for screening oral diseases [7,8]. Such approaches can extend dental expertise to underserved populations and allow asynchronous assessment by dental professionals [9]. Preliminary studies have shown that smartphone intraoral photographs can capture sufficient detail for caries detection in permanent and deciduous dentition [10–12]. However, most research to date has been limited by small sample sizes, heterogeneous methodology, and lack of standardized protocols [13]. Furthermore, there is limited evidence on the feasibility and diagnostic accuracy of mobile intraoral photography specifically for ECC screening in real-world preschool environments. This clinical study aimed to evaluate the diagnostic performance, feasibility, and acceptability of a standardized mobile intraoral photography protocol for ECC screening, using clinical examination as the reference standard.

Study design and setting This was a prospective diagnostic accuracy study conducted over 6 months in five community daycare centers affiliated with a university dental outreach program. Participants Preschool children aged 3–5 years attending participating centers were eligible. Exclusion criteria were: • Known oral pathology other than caries requiring urgent care • Uncooperative behavior preventing safe photography • Parental refusal of consent Procedure Following informed parental consent, trained dental assistants obtained intraoral photographs using a smartphone (12-megapixel camera) with a detachable macro lens and LED ring light. Standardized positioning, cheek retractors, and flash settings were used. Four photographs were taken per child: maxillary occlusal, mandibular occlusal, right buccal, and left buccal. Photographs were anonymized and independently Reviewed by a pediatric dentist (Reviewer A) blinded to clinical findings. The presence of ECC was recorded according to WHO criteria for caries detection (cavitated lesions on smooth or occlusal surfaces). A second pediatric dentist (Reviewer B), blinded to photographic results, conducted a visual-tactile examination in a portable dental chair with appropriate lighting, serving as the reference standard. Outcomes Primary outcome: Sensitivity and specificity of photographic diagnosis compared to clinical examination. Secondary outcomes: • Predictive values and diagnostic agreement (Cohen ’s kappa) • Proportion of usable photographs • Time required per child for photography • Acceptability to parents and dental assistants Data analysis Data were analyzed using descriptive statistics for baseline characteristics. Diagnostic accuracy metrics were calculated with 95% confidence intervals. Agreement between photographic and clinical findings was assessed with Cohen’s kappa. Continuous variables were compared using t-tests, and categorical variables with χ² tests.

Participant characteristics Of 212 children recruited, valid photographs and complete clinical data were obtained for 206 (97.2%). The mean age was 4.2 years (SD 0.8), with 108 males (52.4%) and 98 females (47.6%). Table 1 shows baseline demographic characteristics. Table 1. Baseline characteristics of participants (n=206) Variable Value Age, mean (SD), years 4.2 (0.8) Male sex, n (%) 108 (52.4) Daily toothbrushing reported, n (%) 162 (78.6) Previous dental visit, n (%) 94 (45.6) Sugary snac consumpt on ≥1 ay, n 131 63.6 Diagnostic performance Clinical examination identified ECC in 122/206 children (59.2%). Mobile intraoral photography Correctly identified ECC in 110 of these cases, missing 12 (false negatives), and incorrectly classified 11 children without ECC as positive (false positives). Sensitivity was 90.2% (95% CI 84.0–94.6), specificity 87.1% (95% CI 78.5–93.2), PPV 90.9%, and NPV 86.3%. Cohen’s kappa was 0.77, indicating substantial agreement. Table 2 summarizes diagnostic accuracy metrics. Table 2. Diagnostic accuracy of mobile intraoral hoto ra h com ared to clinical examination Metric Value (95% CI) Sensitivity 90.2% (84.0–94.6) Specificity 87.1% (78.5–93.2) PPV 90.9% NPV 86.3% Cohen’s kappa 0.77 Feasibility outcomes Valid photographs (all required views, in focus, and properly illuminated) were obtained in 97.2% of cases. The median time to complete photography per child was 2.1 minutes (IQR 1.8–2.6). Table 3 outlines feasibility outcomes. Table 3. Feasibility outcomes Outcome Value Proportion with valid photographs 97.2% Median time per child, minutes (IQR) 2.1 ( 1.8–2.6) Assistant-reported ease of use (Likert scale 1–5) Mean 4.7 Interruptions due to uncooperative behavior (%) 5.3 Acceptability Parent survey response rate was 94.1% (194/206). Of respondents, 96% rated the process as acceptable or highly acceptable, and 91% indicated willingness to participate annually. All dental assistants reported that the protocol was easy to integrate into daycare sessions. Table 4 presents acceptability results. Table 4. Acceptability survey responses Group Outcome Value (%) Parents (n=194) Acceptable/highly acceptable 96 Parents (n=194) Willing to participate annually 91 Assistants (n=8) Reported “easy” or “very easy” to implement 100

This prospective clinical study demonstrates that standardized mobile intraoral photography can accurately screen for ECC in preschool children, with sensitivity and specificity above 85% and substantial agreement with clinical examination. These results align with smaller-scale studies showing that smartphone-based dental photography can capture diagnostically useful images for caries detection [7,10,14]. Our sensitivity of 90.2% compares favorably with previous tele-dentistry studies, which have reported ranges from 80% to 92% depending on equipment and evaluator expertise [8,12]. High specificity (87.1%) in our study suggests that mobile photography could reduce false-positive referrals, an important consideration for resource- limited programs. Feasibility was high, with nearly all children yielding usable photographs, and median capture time just over two minutes. This is consistent with other community-based oral imaging studies reporting times between 2–5 minutes per child [11, 15]. Acceptability was excellent among parents and dental assistants, suggesting that integration into preschool health programs is realistic. Parental acceptance has been identified as a key determinant for sustained participation in preventive oral health initiatives [16,17]. Limitations include potential variability in image quality across assistants despite training, and the controlled nature of daycare environments, which may not fully reflect challenges in other community settings. We also did not assess cost- effectiveness or long-term impact on treatment outcomes, both important for policy adoption [18- 20]. Future studies should explore automated image analysis using artificial intelligence to further enhance scalability, and evaluate integration with electronic health records for streamlined referral Pathways.

Mobile intraoral photography using a standardized protocol is a feasible, accurate, and acceptable method for ECC screening in preschool settings. It offers a promising approach for expanding access to early caries detection, especially in communities with limited access to pediatric dental care.

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