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  • br Hypodontia occurs when there is a


    Hypodontia occurs when there is a lack of initiation or interruption of the proliferative stage of odontogenesis. A higher prevalence of hypodontia can be found in the third molars, followed by the second premolars and the upper lateral incisors.28 In our study, hypodontia mainly affected the second premolars in both the SG and the CG, as earlier reported in another study.26 Despite the fact that hypodontia has been reported as being more prevalent in CCS when compared to healthy individuals,9,29,30 it was not detailed which teeth were affected teeth and if hypodontia could affect one or multiple teeth per individual. We considered it important to highlight that in our study of 11 CCS with hypodontia, 7 presented only one case of hypodontia for each individual.
    The DRA were those DA that appeared more exclusively as a late effect of CHT and/or RT in CCS when compared to healthy individuals.20,31 The most vulnerable proliferative K 252a are found in the epithelium of Hertwig sheath, responsible for root formation, which can be affected by CHT and/or RT.32 The odontoblasts are responsible for maintaining the morphogenesis and structure of Hertwig sheath, where the β-catenin odontoblastic molecule acts as an essential regulator of morphogenesis and root development.33 A study in rats
    revealed that after the administration of a chemotherapeutic agent, the dental root development was disrupted causing cellular damage in odontoblasts and Hartwig’s sheath. As a result, the early closure of the apex by impairing the mitotic activity in this region provoked short roots of the teeth in the SG when compared to the CG..34 In our study, DRA affected all types of teeth except the third molar. Among them, the most frequent type of root anomaly was the U1 classification (n = 17), followed by V0 (n = 16), V2 (n = 8), U2 (n = 8) and V1 (n
    In order to better understand the possible factors associated with the most prevalent DA in CCS, we compared DA according to the age of the diagnosis of cancer. It was revealed that microdontia was the only DA that presented an association since 27 of the 35 microdontia occurred in individuals before the age of 71 months. In the literature, studies about the influence of the age of diagnosis are variable. It was reported that CCS diagnosed before 60 months old had a higher number of cases of microdontia, hypodontia and DRA.19,21,30 However, other studies have mentioned that the number of cases of microdontia and hypodontia increased when the cancer diagnosis was shorter than 60 months old and that DRA increased when the age of diagnosis was greater than 60 months old.22,26 Likewise, when we associated DA and the time of duration of the AT, there was no difference between the groups. The treatment time does not seem to influence the occurrence of DA,9,35 probably because the type and dose of CHT and/or RT are more influential than the time of treatment.9,19
    When an individual receives CHT concomitantly with RT in the head and neck area, a higher number of DA can be present when compared to those individuals who had CHT or RT separately.10 In our study, from the 16 types of DA in CCS that were compared regarding the type of AT, impacted teeth were the only DA that showed an association with the type of treatment. There are few studies in the literature evaluating the occurrence of impacted teeth in CCS. Dental eruption begins once the dental crown has formed and the coordinated events between the reabsorption and bone remodelling of the alveolar bone that actively interact among the cells that make up the follicle of the dental germ.36 The osteoblast activity may be affected not only by CHT 37 but also by RT38, that can affect the cells of the follicle of the dental germ causing cellular disorganisation.39 These factors may prevent normal tooth eruption.
    Our study revealed that high quantities of dental abnormalities per individual (10 or >10) were present only in CCS (100%) when compared to CG. This can be explained because CCS can have the presence of DA not only after AT but also before AT. Therefore, if the presence of DA can impact negatively the quality of life in individuals without history of cancer 40, it suggest that the negative impact could be higher in CCS. There are no studies about the influence of DA in the quality of life of CCS, masticatory efficiency and their influence on the nutrition of these individuals; therefore, we suggest studies about these topics are needed.