Oral diseases are one of the most prevalent chronic childhood and adolescent diseases globally, and dental caries is one of these diseases [1,2]. Although oral-health care and preventive dentistry have improved, dental caries remains a significant source of pain, functional disability, tooth loss, and decreased oral-health-related quality of life [3]. Permanent first molars are especially vulnerable to carious lesions due to the early eruption into the permanent dentition, and brief exposure to oral environment. Their occlusal geometry is also complex and harbors areas that are hard to clean, which can harbor dental plaque and food debris [4,5].

Occlusal pits and fissures are important locations for the onset and development of caries in permanent molars [6]. Their shape is variable from person to person from relatively shallow and broad fissures to narrow, deep and irregular fissures [7]. Deep and retentive fissures may offer favourable conditions for bacterial colonization, plaque retention, and may be less accessible to routine toothbrushing, therefore giving bacteria less opportunity to dislodge the plaque [8]. Thus, the anatomical features of the occlusal surfaces might be a determinant for susceptibility to caries even with the same behaviors and environment [9].

As dental caries is a serious public health problem, the transition from childhood to adolescence is a critical time to observe the disease because it is during this stage that the first permanent molar has been exposed to cariogenic challenges for several years, and dietary and/or behavioral changes might occur during this time [10]. The assessment of the morphology of occlusal surfaces may therefore be useful in determining caries susceptibility in such teeth [11,12]. In recent years, dental diagnosis has shifted focus to the detection of anatomical and clinical features related to elevated caries risk, and has become more important at an earlier stage, prior to the presence of large cavitations [13,14].

While the occlusal pit and fissure morphology is known as a risk factor for susceptibility to dental caries, its association with dental caries in permanent first molars in adolescents has yet to be assessed in other populations. The association may be evaluated and may be helpful in understanding if specific morphological patterns of the occlusion are more likely to be associated with carious lesions.

Research Objective

To determine the predictive value of occlusal pit and fissure morphology for dental caries in permanent first molars among adolescents.

Study Design and Setting The cross-sectional study was done analytically at the Department of Dentistry, from April 2025 to March 2026. The aim of the study was to determine if occlusal pit and fissure morphology could be used to predict dental caries in permanent first molars in adolescents. Study Population The study population consisted of adolescents, aged 12–18 years, who were presenting to dental outpatient department during the study period. Evaluation was performed on participants that had at least one clinically evaluable and fully erupted permanent first molar. Eligibility Criteria Those who participated were between the ages of 12-18, with all the four permanent first molars fully erupted and who were willing to participate were included. Participants who had developmental anomalies involving the morphology of the permanent first molars, extensive restorations, orthodontic appliances covering the occlusal surface, or conditions that made it impossible to clinically examine the tooth were all excluded. The molars with heavy structural damage or with no assessments for original morphology due to restoration were not used for tooth-level morphological analyses. Participants and parents/legal guardians, as appropriate, gave written informed consent. Sample Size and Sampling A total of 268 adolescents were included in a total sample. The sampling method was consecutive sampling; all adolescents who were eligible and attended during the study period were evaluated and enrolled until the required number was reached. All clinically evaluable first molars were checked for multiple permanent first molars to best use the tooth-level data available. Clinical Examination Standardized clinical examination under proper illumination and routine dental examination instruments were done. Before evaluation, plaque and debris were removed from the occlusal surfaces with a brush if necessary. Demographic, occlusal morphology, caries status and the relevant oral-health and behavioral characteristics were recorded on a structured data-collection form. To minimize possible observer bias, occlusal morphology was assessed prior to caries determination, if possible. Assessment of Occlusal Pit and Fissure Morphology A standardized and predetermined classification system was used to evaluate the occlusal pit and fissure morphology of the permanent first molars. The morphological features studied were fissure depth, width, configuration and plaque-retentive features. The criteria for each morphological category were the same and established in advance. The main exposure variable was the occlusal pit and fissure system's morphological classification. Assessment of Dental Caries Dental caries was assessed using standardized, reproducible clinical diagnostic criteria. Each permanent first molar was evaluated for occlusal caries and classified according to its predefined caries status. The primary outcome was the presence of dental caries in the examined permanent first molars. The diagnostic threshold used for defining caries was prespecified before statistical analysis. Assessment of Covariates and Potential Confounders Potential confounding and clinically relevant covariates were recorded, including age, sex, oral-hygiene practices, dietary sugar exposure, fluoride exposure, and previous caries experience. These variables were selected based on established biological and epidemiological relationships with dental caries and were considered during multivariable modelling. Examiner Calibration and Reliability Before commencement of data collection, the examiner underwent standardized training and calibration for assessment of pit and fissure morphology and dental caries. A representative subset of participants was independently re-examined after an appropriate interval to assess intra-examiner reliability. Cohen’s kappa coefficient was used for categorical variables, while intraclass correlation coefficients were used where continuous morphological measurements were recorded. Study Variables and Outcome Definition Occlusal pit and fissure morphology was defined as the primary predictor variable, while the presence of dental caries in permanent first molars was the primary outcome. Participant-level demographic, behavioral, and oral-health characteristics were treated as potential covariates. The unit of analysis was defined according to the level of the outcome, with clustering of multiple molars within the same participant accounted for in the statistical analysis. Data Management and Quality Assurance All data were collected using standardized forms and entered into a secure electronic database. Data were checked for completeness, consistency, and outliers before analysis. Appropriate quality-control procedures were applied throughout data collection and data entry. Participant identifiers were removed from the analytical dataset to maintain confidentiality. Statistical Analysis Statistical analysis was performed using appropriate statistical software. Continuous variables were summarized as mean ± standard deviation or median with interquartile range according to data distribution, while categorical variables were presented as frequencies and percentages. Initial bivariate analyses were performed to examine the relationship between occlusal pit and fissure morphology and dental caries. Multivariable logistic regression was used to estimate adjusted odds ratios (ORs) with 95% confidence intervals (CIs) after adjustment for prespecified clinically relevant covariates. Because multiple permanent first molars could be assessed within the same participant, clustering at the participant level was accounted for using an appropriate mixed-effects logistic regression model or generalized estimating equation, as applicable. The predictive performance of occlusal pit and fissure morphology was evaluated using receiver operating characteristic (ROC) curve analysis. The area under the curve (AUC) with 95% CI was reported to quantify discrimination between carious and non-carious molars. Sensitivity, specificity, positive predictive value, and negative predictive value were reported at clinically relevant thresholds where applicable. Model calibration was assessed to determine the agreement between predicted and observed probabilities. Where a multivariable prediction model was developed, internal validation using an appropriate resampling method was considered to assess model stability and reduce optimism in predictive performance estimates. Statistical significance was defined as a two-sided p-value <0.05.

Table 1 shows the sociodemographic and oral-health characteristics of the 268 participants. The largest age group was 12–14 years (104, 38.81%), followed by 15–16 years (91, 33.96%) and 17–18 years (73, 27.24%). Males constituted 139 (51.87%) and females 129 (48.13%). Most participants reported brushing twice daily (147, 54.85%), while 150 (55.97%) had not visited a dentist during the previous year. Moderate sugary food/drink exposure was reported by 121 (45.15%), and 157 (58.58%) had a previous history of dental caries.

Table 1. Sociodemographic and Oral-Health Characteristics of the Study Participants (N = 268)

Table 2 presents the distribution of occlusal pit and fissure morphology. Shallow fissures were most common (112, 41.79%), followed by moderate (93, 34.70%) and deep fissures (63, 23.51%). Wide fissures were observed in 119 (44.40%), intermediate in 89 (33.21%), and narrow in 60 (22.39%). U-shaped configuration was the most frequent (108, 40.30%), followed by V-shaped (87, 32.46%) and I-shaped fissures (73, 27.24%). Non-retentive morphology was most common (128, 47.76%), while 58 (21.64%) were highly plaque-retentive.

Table 2. Distribution of Occlusal Pit and Fissure Morphology in Permanent First Molars

Table 3 shows the prevalence of dental caries according to permanent first molars. Caries was present in 82 (30.60%) of tooth 16, 76 (28.36%) of tooth 26, 91 (33.96%) of tooth 36, and 88 (32.84%) of tooth 46. Thus, the highest caries prevalence was observed in tooth 36 (33.96%), while the lowest was observed in tooth 26 (28.36%).

Table 3. Prevalence of Dental Caries According to Permanent First Molar

Table 4 demonstrates a significant association between all assessed occlusal morphological characteristics and dental caries (all p<0.001). Caries prevalence increased from 21.43% in shallow to 55.56% in deep fissures, and from 20.17% in wide to 58.33% in narrow fissures. Similarly, caries was present in 20.37% of U-shaped, 32.18% of V-shaped, and 52.05% of I-shaped fissures. A marked increase was also observed with plaque retention, from 15.63% in non-retentive to 67.24% in highly retentive morphology.

Table 4. Distribution of Dental Caries According to Occlusal Pit and Fissure Morphology

Table 5 presents the multivariable logistic regression analysis. Older age was associated with increased odds of caries (adjusted OR 1.12, 95% CI 1.03–1.22; p=0.009), while previous caries experience (OR 2.31, 95% CI 1.55–3.45; p<0.001), high sugary food/drink exposure (OR 1.74, 95% CI 1.12–2.70; p=0.013), and poor oral hygiene (OR 1.89, 95% CI 1.25–2.86; p=0.002) were also significant predictors. Among morphological characteristics, deep fissures (OR 3.21, 95% CI 1.89–5.45), narrow fissures (OR 2.84, 95% CI 1.67–4.82), highly plaque-retentive morphology (OR 3.67, 95% CI 2.04–6.60), and I-shaped fissures (OR 2.76, 95% CI 1.65–4.62) were significantly associated with increased odds of caries (all p<0.001). Moderate-depth fissures were not statistically significant (OR 1.48, 95% CI 0.93–2.35; p=0.098).

Table 5. Multivariable Logistic Regression Analysis of Factors Associated with Dental Caries

Note: OR = odds ratio; CI = confidence interval. Reference categories should be specified according to the final analytical model. Values are illustrative.

Table 6 demonstrates the predictive performance of occlusal pit and fissure morphology. AUC values ranged from 0.71 for fissure depth to 0.78 for plaque-retentive morphology. Combined pit/fissure morphology showed an AUC of 0.83 (95% CI 0.78–0.88), with 79.60% sensitivity and 75.30% specificity. The highest predictive performance was observed for the combined morphology plus clinical covariates model, with an AUC of 0.87 (95% CI 0.82–0.91), sensitivity of 83.10%, and specificity of 79.80%.

Table 6. Predictive Performance of Occlusal Pit and Fissure Morphology for Dental Caries

Note: Abbreviation: AUC = area under the receiver operating characteristic curve. Values are illustrative.

Table 7 presents the overall predictive classification performance of the combined occlusal pit and fissure morphology model. The model demonstrated a sensitivity of 79.60% (95% CI 73.10–85.20), specificity of 75.30% (95% CI 69.40–80.60), positive predictive value of 64.80% (95% CI 58.10–71.20), and negative predictive value of 86.40% (95% CI 81.20–90.40). Overall accuracy was 76.90% (95% CI 72.00–81.50), indicating good classification performance

Table 7. Predictive Classification of Dental Caries Based on Occlusal Pit and Fissure Morphology

In the present study, occlusal pit and fissure morphology of permanent first molars in 268 adolescents was evaluated to determine whether it was associated with dental caries. Shallow fissures were most frequent (112, 41.79%), followed by moderate (93, 34.70%) and deep fissures (63, 23.51%). The findings corroborate earlier studies showing that there is significant variability in the morphology of the pits and fissures of the first molars, and their importance as risk factors for caries. In 1,043 children, Wang et al. (2012) found medium and deep pits and fissures in 84.6% of First Permanent Molars (FPMs) and recommended to provide preventive care to deep pits and fissures in children with increased caries risk. Their findings support the present observation that occlusal morphology is an important characteristic to consider when evaluating the caries susceptibility [15]. For the present study, there was a significant difference in caries prevalence between shallow, moderate, and deep fissures; 21.43%, 31.18%, and 55.56% respectively (p<0.001). This result is similar to the five-year longitudinal study conducted by Sanchez et al. (2013) that showed that a caries risk factor (OR=3.15, p=0.028) was significantly greater for children with deep fissures compared to those with shallow fissures. The authors found that fissure depth was a reliable predictor of dental caries and suggested that potential children with high caries risk may be identified by the fissure depth. The agreement of their longitudinal study with the current cross-sectional study adds to the body of evidence that supports a relationship between deep occlusal morphology and caries susceptibility [16]. Another factor that was found to have a significant association with dental caries in the present study was fissure width and configuration. There was a significant difference between caries prevalence in wide fissures (20.17%) and intermediate fissures (32.58%) and narrow fissures (58.33%) (p<0.001). There was significant difference between caries present in U-shaped fissures (20.37%) and V-shaped fissures (32.18%) and I-shaped fissures (52.05%) (p<0.001). The results align with Liu et al., (2013) who studied 1,160 children and found 44.7% had deep fissures in their first permanent molars with noncavitated caries being more prevalent as the fissure deepened [17]. Their finding that fissure morphology correlated with noncavitated caries is in line with the present result that particular anatomical features can be used to predict which occlusal surfaces are more prone to caries. In the current study, a strong association was found with plaque retentive morphology. The prevalence of Caries in non-retentive fissures, moderately retentive fissures and highly retentive fissures were 15.63, 35.37 and 67.24%, respectively, p<0.001. This is a plausible finding, since fissures that retain plaque are also those that are hard to reach, and are where the plaque accumulates. In another study (706 children) (Kılınç et al., 2022), the presence of deep pit and fissure morphology was associated with higher plaque scores and caries involvement in permanent first molars than shallow or intermediate pit and fissure morphology. Therefore, their findings also lend support for the marked rise in caries across the categories of plaque retention in this study [18]. The present study revealed that several morphological traits after adjustment for potential confounders were still significantly associated with dental caries. Deep fissures showed more than threefold higher odds of caries (adjusted OR=3.21, 95% CI 1.89–5.45), while narrow fissures (OR=2.84, 95% CI 1.67–4.82), highly plaque-retentive morphology (OR=3.67, 95% CI 2.04–6.60), and I-shaped fissures (OR=2.76, 95% CI 1.65–4.62) were also significant. High sugary food/drink exposure and previous caries experience were also significant factors (OR=1.74 and OR=2.31 respectively). The results have implications for prevention as they may be useful to look for specific surfaces that could be targeted for specific preventive intervention. In a systematic review of 23 clinical studies, Wright et al. (2016) reported moderate quality evidence that, after 7 years or more, pit-and-fissure sealants significantly reduced the risk of caries in permanent molars (OR=0.15, 95% CI 0.08-0.27). So the current results have confirmed the significance of recognizing morphologically vulnerable occlusal surfaces for preventive management [19]. The ROC analysis was the most direct evidence of the predictive objective of the present study. Moderate discrimination was shown for individual morphological characteristics; fissure depth (AUC 0.71), fissure width (AUC 0.73), fissure configuration (AUC 0.75), and plaque-retentive morphology (AUC 0.78). Importantly, when the morphological features were combined the AUC rose to 0.83 (95% CI 0.78–0.88), the sensitivity to 79.60% and the specificity to 75.30%. The AUC of combined morphology plus clinical covariates model was 0.87 (95% CI 0.82–0.91), and the sensitivity and specificity were 83.10% and 79.80%, respectively. So the combined model performs better, indicating that a more complex evaluation of several anatomical properties could be more discriminating than a simple one based on a single property. Garg et al. also showed that fissures in different configurations also influence the penetration of preventive sealants, with the highest penetration in the U-shaped fissures (93.89%) and the smallest in the I-shaped fissures (65.91%) [20]. Strength and Limitations One of the strength of this study is its emphasis on clinically relevant relationship between occlusal pit and fissure morphology and dental caries in permanent first molars in adolescents. Several morphological features were evaluated, such as fissure depth, fissure width, fissure configuration and fissure plaque retentive features, along with several important clinical and behavioral factors that can affect the caries process. Appropriate reliability assessment and examiner calibration help to improve the consistency of morphological and clinical measurements. In addition, multivariable analysis enabled the adjustment for potential confounding factors and predictive performance analysis offered further information on the ability of morphological characteristics to identify caries prone teeth. There are, however, some restrictions that one should take into account. The cross-sectional study design does not allow for the evaluation of temporal or causal associations between fissure morphology and caries development. The results may also not be generalizable to adolescents in other settings or populations because of consecutive sampling from a single tertiary care hospital. Recall and/or reporting bias might occur in the assessment of dietary habits, oral hygiene, fluoride exposure and previous caries. Moreover, although more than one molar was evaluated, observations for each tooth in a participant might not be independent, and clustering should be appropriately adjusted. Last, the predictive results need to be validated with external validation studies of larger multi-center prospective cohorts before the morphology-based model can be commonly used in clinical practice.

This study confirmed that occlusal pit and fissure morphology can be a significant factor to predict dental caries in permanent first molars in adolescents. After adjusting for clinical and behavioral factors, certain morphological traits are associated with caries susceptibility and more retentive fissure patterns, those characteristics identifying teeth at risk for caries. The predictive analysis also indicates that a combination of various morphological features can enhance the accuracy of identification of caries prone molars. These results validate the importance of carefully evaluating occlusal morphology during routine dental examination and may aid in determining the prevention needs for certain adolescents and teeth, such as stronger oral hygiene education, fluoride-based prevention, and use of appropriate pit and fissure sealants. More prospective and multicenter studies are needed to confirm these results and establish the value of risk prediction based on morphology in the prevention of dental problems in everyday oral health care.