Reasons for the highest caries prevalence in the mandibular first molars

The mandibular first permanent molar has the highest prevalence of dental caries, possibly due to frequent eating, which increases the activity of cariogenic bacteria in the mouth. Additionally, food debris accumulation combined with poor oral hygiene habits may contribute to this high rate of decay in the mandibular first permanent molar.

The first permanent molar, also known as the "six-year molar," typically erupts around age six and remains for life without replacement. Since this tooth emerges early during the mixed dentition stage—when most other teeth in the mouth are still primary teeth—the relatively soft diet and high frequency of eating can promote greater activity, diversity, and virulence of cariogenic bacteria in the oral environment. Under these conditions, the first permanent molar is particularly susceptible to developing dental caries.

The occlusal surface of molars is uneven, with numerous pits and fissures where food debris easily accumulates. Combined with poor oral hygiene practices, this often leads to pit-and-fissure caries. Furthermore, due to gravity, bacterial plaque tends to accumulate more on the gingival surfaces of mandibular molars than on maxillary molars, increasing the risk of caries. Therefore, it is recommended to implement preventive measures such as pit-and-fissure sealants for six-year molars to prevent tooth decay.

It is advisable to maintain regular dental check-ups and consistent proper brushing habits, which can effectively protect overall dental health.