# Prevalence of Root Canal Treatments among Diabetic Patients: Systematic Review and Meta-Analysis
## 4 Discussion  
The aim of this study was to conduct a systematic review to determine the prevalence of RFT among the diabetic adult population. According to the raw data from the primary study, it can be concluded that the prevalence of RFT among the diabetic adult population over 18 years is 5.5%, with 42.7% of diabetic people having one or more RFT. The systematic review and meta-analysis of prevalence and incidence are emergent methodologies in the field of evidence synthesis. The traditionally used PICO strategy does not agree with prevalence studies, so the CoCoPop rule was used [32]. Taking into account the worldwide prevalence of RFT (8.3% of teeth and 55.7% of people) [6], the results of this study show a strikingly lower prevalence of RFT among diabetics compared to that of the general population. Moreover, the prevalence of RFT is an indicator of the frequency of endodontic infections and, at least apparently, these results are not consistent with the higher prevalence of AP among diabetic patients that has been shown [13; 14; 15; 21; 22; 38]. On the contrary, an increase in the prevalence of RCT could be expected among the adult diabetic population. However, the explanation for the lower prevalence of RFT among diabetics probably lies in the fact that diabetic patients suffer from post-treatment AP more frequently [24; 42], which is possibly consecutive to a delay in the healing of periapical tissues [43; 44]. The persistence of AP among diabetics after RCT leads, in some cases, to tooth extraction. In fact, type 2 diabetes is associated with greater loss of RFT [23], and most of the studies included in the present study [11; 13; 14; 15; 16; 21] refer to type 2 diabetics. However, since it is not possible to learn about the quality of RCT or other possible prognostic factors, no definitive conclusions can be drawn in this regard. Diabetes mellitus includes a group of disorders of the metabolism of carbohydrates, lipids and proteins, the main manifestation of which is hyperglycemia, as a result of a deficiency in insulin secretion, a lack of insulin action, or both [19]. Chronic hyperglycemia is associated with glucotoxicity and the damage and dysfunction of various organs, especially the eyes, kidneys, nerves, heart and blood vessels [19; 20]. The results of several studies support a relationship between the prevalence of AP and diabetes [7; 11; 15; 16; 21; 22; 39]. Furthermore, several systematic reviews and meta-analyses have found a significant association between the endodontic treatment outcome and diabetes [23; 24; 26]. On the other hand, several studies have found a correlation between the higher prevalence of AP and poor glycemic control among diabetic patients [13; 14; 16]. In short, there seems to be a mutual influence between diabetes and AP [7; 45]. The pro-inflammatory state and impaired immune response associated with diabetes may affect the reparative response of the periapical tissue, influencing the two main endodontic variables: the prevalence of AP and the frequency of RCT [46]. Innate immunity is the first line of defense against pathogens. Systemic conditions that alter the functions of innate immunity cells, such as diabetes, decrease neutrophil phagocytosis or macrophage chemotaxis, causing an inflammatory state that alters cell proliferation, delaying lesion healing. Especially in poorly controlled diabetic patients, a stronger systemic inflammatory reaction may be induced, with the activation of NF-\(\kappa\beta\) in macrophages and increased cellular oxidative stress, which may impair bone turnover and periapical wound healing [47]. These clinical situations are characterized by increased C-reactive protein levels in serum and the release of potentially tissue-destructive substances, such as reactive oxygen species, collagenase, serine proteases and the up-regulation of pro-inflammatory cytokines (IL-1b, IL-6, IL-8, IL-10 and TNF-\(\alpha\)) [7].