Dental caries is still one of the most important preventable oral diseases and is still a significant burden on children and adolescents across the globe.[1] It is estimated that nearly 45% of the world's population, or about 3.5 billion people, have oral disease; and that an estimated 2.5 billion people have untreated dental caries.[2] Dental caries of permanent teeth is especially significant during adolescence, because the permanent dentition is subjected to cariogenic challenges for increasingly longer periods.[3]

The permanent first molar is one of the most susceptible teeth to dental caries due to its early eruption, long time in the oral cavity, and occlusal anatomy.[4] They have pits, grooves, and fissures on the occlusal surfaces that may trap plaque and fermentable carbohydrates and can be difficult to clean properly with regular brushing.[5] Carious lesions in pits and fissures are specifically identified as a significant component of untreated coronal carious lesions

by WHO.[6] Other factors that affect the susceptibility of the first permanent molars include the maturation of newly erupted enamel, oral hygiene, fluoride exposure, diet, and socioeconomic factors.[7]

The morphology of the occlusal surface may be a significant anatomical risk factor for caries.[8] The depth, shape, and complexity of pits and fissures, and the shape of individual cusps and developmental grooves, can affect the retention of plaque and the ease with which it can be effectively removed.[8] A recent clinical study of permanent first molars found that deep pit and fissure morphology was significantly related to higher levels of caries involvement and plaque retention than shallow and intermediate pit and fissure morphologies.[9]

Likewise, recent morphologic studies showed significant variation in the fissure pattern and depth in permanent molars, which argues for the non-uniformity of occlusal morphology between people.[10] Adolescence is a critical age to explore this association as dentition, oral hygiene habits, food intake, and exposure to caries damage undergo significant changes.[11] Traditional caries-risk assessment usually includes behavioral, diet, and socioeconomic risk factors, but anatomical factors of the tooth itself may give further information when identifying teeth at risk.[12] In addition, recent research has indicated that certain morphological features, which include prominent developmental features of permanent molars, could be linked to caries susceptibility.[13] Thus, evaluating the occlusal morphological differences in combination with caries status may be a clinically relevant means for pre-cavitation diagnosis of anatomically susceptible permanent first molars. This information can guide the clinician in prioritizing pit-and fissure sealants, preventive fluoride measures, and individual oral hygiene instruction and follow-up of high-risk adolescents with occlusal anatomy. The present study was thus conducted to see if any difference in occlusal surface morphology of the permanent first molar is related to dental caries susceptibility among adolescents. This study was designed to evaluate the correlation between occlusal surface morphological variations and dental caries susceptibility in permanent first molars among adolescents.

A cross-sectional analytical study was done in the Department of paeds. The study was carried out over a period of six months from November, 2025 to April, 2026 The minimum sample size was determined with OpenEpi version 3.01 using a 95% confidence level, 5% absolute precision, and the prevalence of permanent first-molar involvement as 62.5%, which resulted in an approximation of 400 participants.[14] The sampling technique employed was non-probability consecutive sampling. All adolescents between 10 and 19 years of age were included, regardless of their gender. Patients were asked to present at least one clinically erupted permanent first molar with an accessible occlusal surface to examine the morphology of pits and fissures and dental caries. Children who had developmental anomalies of the permanent first molars, extensive restorations on the occlusal surface, orthodontic appliances that prevented adequate examination, or children who had their permanent first molars extracted were excluded. Adolescents with a systemic condition or disability that made an oral examination unreliable were also excluded. Teeth with extensive structural destruction in which the original occlusal morphology could not be assessed were not included in the morphological analysis. Demographic data like age and sex were collected after informed consent and assent on a structured proforma for data collection. The clinical oral examination was then made under sufficient illumination with a mouth mirror, dental explorer/probe, and cotton rolls after removal of gross plaque and debris. Each permanent first molar was assessed separately and assessed for presence, eruption, occlusal morphology, and caries status. The occlusal morphology was evaluated by the shape and depth of the pits and fissures. The fissures were divided into three groups according to the clinical shape and visibility of the fissure with the examination probe: shallow, intermediate, and deep fissures. Other morphologic features such as complexity of occlusal groove pattern and presence of prominent pits or developmental grooves were recorded as applicable. The degree of morphological exposure was determined based on the most clinically relevant pit-and fissure pattern of each permanent first molar and classified into the following categories: the principal morphological exposure. Standardized clinical criteria were used for dental caries assessment, and the data were recorded separately for each permanent 1st molar. Carious lesions were classified based on their clinical severity as sound tooth surface, non-cavitated carious lesion, and cavitated carious lesion. A DMFT index was also recorded for an overall assessment of caries experience in the permanent dentition. The assessment was done prior to any surgical intervention. To reduce inter-examiner variation, the examiner was calibrated prior to the start of the study with a series of patients who were not used for the final analysis. All participants were then examined using the same criteria and procedure. A subsample of participants was rescreened to determine intra-examiner reliability, and the kappa statistic was used to determine agreement. IBM SPSS Statistics was used to enter and analyze the data. Categorical variables including gender, fissure morphology, and caries status) were summarized as frequencies and percentages, while continuous variables including age and DMFT score were summarized as mean±SD and median (IQR). The normality of continuous variables was assessed using the Shapiro-Wilk test. The chi-square test was used to evaluate the association between occlusal morphological characteristics and dental caries status. The mean DMFT scores were compared between different categories of occlusal morphology by performing one-way analysis of variance for data with normal distribution and the Kruskal–Wallis test for data with non-normal distribution. Pearson or Spearman correlation was used to determine correlations between morphological features and caries experience, depending on the distribution of the data. A binary logistic regression was then conducted to see if deep or complex occlusal morphology was independently related to the presence of dental caries, with age, sex and oral-hygiene status included as potential confounding factors. Odds ratios (ORs) and 95% confidence intervals (CIs) were presented. A p-value of <0.05 was considered statistically significant.

A total of 400 adolescents (51.8% male and 48.3% female) aged 14.8 ± 2.7 years were included in the study. Oral hygiene was considered fair in 46.0% of the participants, and dental caries was present in at least one of the permanent first molars in 54.5%. The mean DMFT score was 2.41 ± 1.86. (Table 1)

Of 1,600 permanent first molars examined, intermediate pit/fissures were most prevalent (44.6%), shallow pit/fissures (28.9%), and deep pit/fissures (26.5%). A high proportion of molars had V-shaped fissures (36.4%) and complex groove patterns (38.4%), while prominent developmental pits and deep isolated pits occurred in 29.5% and 19.6% of molars, respectively. (Table 2)

There was a significant correlation between dental caries and pit and fissure depth: shallow pit and fissure (17.7%), intermediate pit and fissure (45.8%), and deep pit and fissure (68.2%) (χ²=72.84, p<0.001). (Table 3)

Caries was also seen to be significantly higher in irregular/complex fissure configuration, complex groove patterns, prominent developmental pits and deep isolated pits. The association of each of these morphological features and caries status was significant (p<0.001). (Table 4)

A significant correlation was observed between the mean DMFT scores and the occlusal morphological risk, ranging from 1.48 ± 1.21 in the low risk group to 3.57 ± 2.08 in the high risk group (p<0.001). Poor oral hygiene and older age were also associated with higher DMFT scores, but there was no significant difference in DMFT scores between sex (p=0.481). (Table 5)

Deep pit & fissure morphology remained the best independent predictor of caries even after adjusting for age, sex and oral hygiene (p<0.001). Complex/irregular fissures, complex grooves, prominent developmental pits, and deep isolated pits were also associated with an increased risk of dental caries independently. (Table 6)

Table 1. Demographic and clinical characteristics of study participants (n=400)

Table 2. Occlusal morphological characteristics of permanent first molars

Table 3. Association between pit-and-fissure depth and dental caries status

Table 4. Association of occlusal morphological characteristics with dental caries

Table 5. Comparison of DMFT scores and caries experience according to occlusal morphology and oral-hygiene status

Table 6. Binary logistic regression analysis of factors associated with dental caries in permanent first molars

The present study was able to show that there was a distinct link between the occlusal surface morphology and dental caries susceptibility of permanent first molars among adolescents aged 10-19 years. In the majority of the participants, caries was present in at least one permanent first molar, and deep pit and fissure morphology was strongly correlated with caries. The results confirm the hypothesis that the anatomical morphology of the occlusal surface plays an important role in plaque retention and caries formation, especially for the early deciduous and permanent first molars because they are exposed to the oral cavity for a longer period of time. A recent study published in 2026 also highlighted that the early emergence of the permanent first molars coupled with their complicated occlusal anatomy makes them more susceptible to plaque accumulation and dental caries.[15, 16] The present result of a significant difference in the involvement of caries between the deep fissure versus shallow fissure group was very similar to the result obtained from the study carried out by Kılınç et al. in 2022 on 706 children aged 7–12 years. They found that 62.5% had affected permanent first molars, with intermediate fissure being the most common morphology, and found significantly more caries involvement and plaque accumulation in teeth with deep pits and fissures. In the same way, our results indicated the same association, with a slightly greater magnitude of caries among deep fissures in our adolescent population, which may be due to a longer cumulative exposure to cariogenic factors as the age increases.[9, 17] The intermediate morphology, which was the most common fissure depth in our study, was also similar to that of the Turkish study, which found intermediate fissures to be the most common in permanent first molars at 57.5%. Our study, however, showed a slightly lower percentage of intermediate fissures and a higher percentage of deep fissures. This variation might be due to age distribution, population characteristics, diagnostic classification, and examiner assessment. Importantly, both studies showed that morphology should not be treated as an anatomical description, but could be a potentially clinically relevant characteristic for caries-risk assessment.[9] This strong association between complex/irregular fissure configuration and caries was biologically plausible as it is thought that narrow and complicated fissure systems may harbor bacterial retention and/or make mechanical plaque removal difficult. Hristov et al (2024) found that there was significant variation in the anatomy of molar fissures and that the fissure depth of permanent molars was significantly greater than that of primary molars using micro-computed tomography and 3D modelling. We observe that deeper and more complicated fissure configurations may be high-risk occlusal surfaces, and this is confirmed anatomically by their findings.[10] The results were also corroborated by the methodological study conducted by Mace et al. (2023) that tried to quantify occlusal and fissure morphology of permanent first molars in an objective manner using three-dimensional measurements. While all such measurements were not statistically related to caries-related outcomes in that study, certain geometric measurements were linked to measurable relationships with the occlusal surface characteristics. The slight differences between our results and the 2023 study could be due to methodological differences, as our study was based on clinical recognition of the morphological categories, whereas the 2023 study was based on 3D quantitative measurements.[18] Caries rate was higher in the more complex (posterior) teeth, which is consistent with the literature today which supports the author's findings that pit and fissure caries is more common than other types of caries in the posterior teeth. In one observational study from a 2023 review, 79% of decayed molars had lesions in the occlusal fissure areas. The authors emphasized the significance of fissure sealing, as it is a niche which is hard to clean and vulnerable to caries. This confirms the clinical implications of our results and implies that morphological evaluation might be integrated into preventive decision-making.[19] In the present study, the independent association of poor oral hygiene with caries was also observed. This is significant because morphology does not account for caries; rather, the presence of deep or complex fissures can be associated with other environmental risk factors and plaque accumulation. The same study in Turkey in 2022 reported significantly more plaque accumulation on permanent first molars with deep fissures, providing another possible mechanism that could be associated with increased caries susceptibility.[9] The higher the DMFT score, the stronger the association we found in our study, with DMFT scores being increased in the progressive order in the low, moderate, and high-risk occlusal morphology groups. The present finding implies that adolescents with more anatomically retentive surfaces could gain more caries experience as time goes by. An epidemiological study of 8–10-year-old children revealed that there were significantly fewer non-cavitated and cavitated carious lesions in the sealed molars than in the unsealed molars, which lends indirect support to this interpretation.[20] Our results are also relevant to current evidence of pit and fissure sealants. In an umbrella review of systematic reviews, Amend et al. (2024) found sealants to be more effective than no intervention for caries in permanent molars, with varying levels of certainty across reviews. Likewise, a 2024 evidence review of sealants found that, as a whole, sealants do not appear to be less effective than alternative preventive methods for arresting or preventing occlusal caries. The practical impact of our study is further supported by these findings, which suggest that there may be a need for specific preventive measures for adolescents with deep fissures or with complex fissures in addition to more general oral hygiene information.[21] More recent clinical studies of permanent first molars also highlight the need to recognize anatomically susceptible teeth. In Pakistan, Nazir et al. (2024) examined pit-and-fissure sealants in children aged between 7 and 12 years who had pit and fissure carious lesions, underscoring the clinical significance of pit and fissure surfaces in young children.[22] Similarly, Saravanan et al. (2024) showed that children with effective pit-and-fissure sealants in their permanent molars had fewer caries findings. Although these studies focused on preventive treatment and not on morphology per se, their results do support our findings that clinically vulnerable occlusal anatomy is indeed an appropriate target for preventive management.[23] It is also interesting to compare the results of the Pakistani research conducted on other morphological traits in recent years. In the study of 432 participants in Lahore in 2025, the more prominent the Cusp of Carabelli, the higher the caries susceptibility in maxillary molars, with more morphologically prominent forms carrying a higher risk. On the other hand, a recent study in Peshawar failed to show any association between the Cusp of Carabelli morphology and Caries experience. These opposing results highlight that different dental morphological traits might be associated with caries in a different manner depending on the type of feature, population, and evaluation procedure. The occlusal pit and fissure morphology of the permanent first molar was specifically investigated, and a strong association was found, especially for the deep and complex configurations.[24] It is especially significant that the effect of deep fissure morphology in our multivariable analysis was independent. The association between deep fissures and higher risk for caries was consistent after adjusting for age, sex, and oral hygiene, indicating that the relationship was independent of demographic and hygiene factors. This observation is in accordance with the biological principle that bacteria and food particles can hide and get trapped in narrow and deep fissures from regular mechanical plaque removal. However, because the present study is cross-sectional, temporal or causal conclusions cannot be made, and deep morphology should be interpreted as an index of increased susceptibility and not as a definite risk factor for caries. Overall, the findings suggest that occlusal morphology may represent a clinically useful anatomic element for assessing the risk for caries in adolescents. The results of our study are consistent with recent morphological, epidemiological, and preventive studies, justifying the increased monitoring of permanent first molars with deep, complex, or irregular fissures. Clinically, morphological evaluation might be useful for the identification of young patients who may need personalized preventive interventions such as additional oral hygiene instructions, fluoride pastes, and pit-and-fissure sealants. Further prospective research with longitudinal follow-up is justified using standardized 3D imaging and longitudinal follow-up to identify morphological features that predict the development of caries prior to its clinical appearance. Limitations There were a number of limitations in the study. The cross-sectional design limited the ability to determine a temporal or causal relationship between occlusal morphology and subsequent development of dental caries. The study population was not randomly sampled, and the findings may not be extrapolatable to the broader adolescent population, as the study was conducted at a single tertiary-care dental hospital. The occlusal morphology was evaluated clinically and not by the use of a more sophisticated 3-D imaging system, so the depth and configuration of the fissure may have been subjectively classified. Some other factors that may be potential confounders, such as dietary sugar intake, fluoride exposure, socioeconomic status, salivary characteristics, and previous preventive treatment, were not fully evaluated. Moreover, clinical assessment of caries was performed, potentially underestimating early or subclinical lesions. Overall, longitudinal multicenter studies with standardized digital or 3D morphological assessment and detailed behavioral and dietary variables are recommended to confirm these data.

Occlusal surface morphology was found to be significantly related to dental caries susceptibility in permanent first molars for the age group 10-19 years. Deep pits and fissures, complex or irregular fissure configuration, complex grooves, and deep individual pits had a significant association with more carious involvement. Fissures with greater depth and fissure configurations that were complex or irregular, complex grooves, and deep individual pits showed significant association with increased caries involvement. After controlling for pertinent demographic and oral-hygiene variables, deep fissure morphology was the best independent predictor. The results indicate that occlusal morphology can be used in addition to traditional caries-risk assessment and assist the clinician in the identification of close monitoring and preventive care for the permanent first molar, including pit and fissure sealants, fluoride application, and individualized oral-hygiene counseling.

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