# The Pathology of the First Permanent Molar during the Mixed Dentition Stage--Review
## 3 Results and Discussion
### Pathology of the Dental Hard Tissues
#### 3.2.2 Dental Caries
Decay incidence increased with patients' age, such as the group of 8-9-year-old children examined presented the highest percentage (14.1%; n = 282), followed by the 7-8-year-old group (10.2%; n = 191) and 6-7-year-old group (6.6%; n = 101). The use of fissure sealants revealed a low distribution in the sample examined (0.8%, 0.3%, and 0.4%, respectively). From the total of 27 filled first permanent molars (0.5%), the highest prevalence was found in the third-grade children (n = 23; 1.1%), followed by the first-grade children (n = 3; 0.2%) and the second-grade children (n = 1; 0.05%) [90]. In a 2020 study by [PERSON] and [PERSON], 398 (51.2%) of the 778 Turkish children, 7- to 9- years old, had caries experience in the FPM [110]. The age distribution of caries lesions in the sample examined was 41.2% (n = 96) in the seven-year-old children, followed by 51.6% (n = 160) in the eight-year-olds and 60.4% (n = 142) in the nine-year-olds. These results highlighted that caries prevalence increased with age. Various lesions were more common in the mandibular FPMs (51.6%) than in the maxillary FPMs (48.4%). The mean DMFTs were 1.35 in girls and 1.05 in boys, and sex-based statistically significant differences were found (\(p<0.01\) by independent \(t\)-test). Of real concern was the finding that 10% of the FPMs exhibited extensive caries within two-three years after eruption [110]. Extensive-stage caries were more prevalent in mandibular FPMs than in maxillary FPMs, with statistical significance (\(p<0.05\)) [110]. In the study by [PERSON] et al., the high prevalence of dental caries in the mixed dentition stage was associated with low socio-economic status and several behavioral factors, including the duration of tooth brushing and previous dental treatments and emergency visits [111]. Therefore, efforts should be made to address these factors, to improve oral health behavior and the use of oral health care services [111]. A cohort study on a group of children seven to eight years old from Tehran (Iran) showed that 53% of the subjects developed at least one new dental caries at the level of the FPMs within two years, and according to the CAST (Caries Assessment Spectrum and Treatment) index and OHI-S (Oral Hygiene Index-Simplified), this finding was associated with socio-economic status and mother's education but was not associated with sweets consumption and oral hygiene [112]. The study also revealed no statistically significant correlations between caries occurrence and gender [112]. [PERSON] and [PERSON], 2021, in their study carried out on a community in the Eastern Anatolia region of Turkey, showed that the FPMs are among the teeth most affected by caries during childhood, and the prevalence of these lesions increases with age [113]. Mandibular FPMs were more frequently affected than their maxillary counterparts, without significant left/right differences. The authors also showed that the prevalence of dental caries in the FPM, according to gender, was higher among girls compared to boys, and the fact that tooth eruption occurs earlier in girls compared to boys could explain this result due to the time of longer exposure of the FPM to cariogenic agents [113]. There are authors who showed that it is possible to identify the risk of dental caries in FPMs based on primary molar curious experience, the condition of deciduous second molar being of particular importance on caries development in adjacent FPM. [PERSON] et al., 2004, showed that dental caries were frequently located on the mesial surface of the FPMs and found strong correlations between the presence of caries on the distal surface of the primary second molar and the occurrence of the disease in the mesial surface of the adjacent FPM [114].