# 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
[PERSON] et al., 2001, investigating 374 children during their mean ages of 6.7 to 11.5 years, showed that there is a close correlation between the caries status of the distal surface of the second primary molar and the caries rate for the mesial surface of the FPM and that FPM caries rate was 15 times higher in cases of enamel/enamel-dentin border caries on the second primary molars compared to cases of sound deciduous molars [115]. [PERSON] et al., examining annually 4468 children during their primary school time, identified that cavity formation in FPMs was strongly influenced by the status of the adjacent primary molars, the effect of the second deciduous molar being the most pronounced [116]. In cases where both primary molars were affected by dental caries, in association with a poor oral environment, a peak in cavity formation in the FPM one to two years after emerging from the mucosa was registered [116]. In a recent (2021) cross-sectional study that assessed 413 children 7- and 8-year-old, [PERSON] et al. found that in cases of sound primary first molars, 22.9% of the adjacent FPMswere also sound, and in cases of sound primary second molars, 25.7% of the FPMs in the same quadrant were also sound [117]. A stronger correlation between a carious primary second molar and the development of dentin caries in the adjacent FPM than in cases of a carious primary first molar was noticed (\(p<0.001\)) [117]. Particularities of Approaching the Child with FPM Caries  
The preservation of FPM health is an important determining factor for future oral health [102]. Risk assessment is the first step in caries management because multiple risk factors for caries attack on FPM are related to the challenging and dynamic period of mixed dentition [118]. The interval between the initiation of tooth eruption and the tooth coming into full functional occlusion is considered an important time for FPM caries prevention intervention [100]. Preventive care is implemented throughout the entire period of transition between the primary and permanent dentition and continues afterward. The prevention strategy includes oral health education, fluoride administration, use of pit and fissure sealants, and risk-oriented timing of recall visits [118]. Pit and fissure sealants are the preferred methods for the prevention of FPM occlusal caries in children who are at high risk and have barriers to accessing dental care [119]. School-based sealant programs should target kindergarten children and first graders, with follow-up programs for second-grade children [107]. When operative intervention is necessary, the principles of preserving healthy hard dental tissues and pulp vitality are applied [118; 120]. The life-long need for restoration replacement has also to be taken into consideration [91]. Cases of teeth with extensive caries must be carefully assessed as heavily restored teeth enter a restorative cycle leading to dental extraction [121]. Late extraction of FPM generates the need to restore the edentulous space [121]. Therefore, in order to avoid the occlusal and prosthetic complications determined by FPM extraction later in life, [PERSON] et al. recommend that extraction during the mixed dentition stage could be the treatment of choice for FPMs with poor prognosis, making space for the second permanent molars to favorably erupt in the place of FPMs [121]. According to [PERSON] et al., 2015, extraction of the mandibular FPM during the mixed dentition stage has a favorable outcome because the maxillary FPM on the opposing dental arch remains in contact with the primary second molar and vertical migrations are minor [122]. In a 2018 systematic review concerning the consequences of FPM early extraction, [PERSON] et al. concluded that the ideal time for FPM extraction to achieve complete closure of the edentulous span is when the second permanent molar is at the early bifurcation stage of its development [123]. [PERSON] et al., 2013 reported higher rates of space closure in the maxilla than in the mandible (92% vs. 66%) [92].