## 4 Discussion  
T2 DM is the most common form of all DM and the number of affected patients were on the rise. T2 DM was linked to being overweight and obese [6]. BMI and waist circumference are the most common measurements for obesity. In this study, both T2 DM and healthy had normal range of BMI and WC demonstrating that none of the participants were obese. There were studies about the success and survival of dental implants in T2 DM patients in recent systematic reviews [29; 42]. Good glycemic control seemed to be closely associated with the higher survival rate and fewer complications of dental implants in T2 DM patients. FPG and HbA1c are the most commonly used parameters to determine glycemic status for T2 DM; however, HbA1c is considered more reliable since it indicates the average glycemic status of T2 DM patients in the last 3 months due to the life cycle of red blood cells [16]. Only T2 DM patients with well-controlled glycemic status having HbA1c below 8% were included in this study. Clinically and histologically, all implants were successfully integrated to the alveolar bone. Only patients with a missing tooth on the maxilla in the premolar and molar region were included in this study. Peri-implant bone healing in the posterior maxilla is more rapid than in other areas of the jaw bones. Posterior maxilla consists of almost all trabecular bone; therefor, bone regeneration and remodeling are far quicker than in cortical bone. In addition, osteoconduction and de-novo bone formation only occur in peri-implant healing in trabecular bone [43]. Therefore, premolar and molar of maxilla were chosen for this study. Bone histomorphometry is crucial for understanding osseointegration of dental implant. Osseointegration has been defined as a direct and functional connection between bone and an artificial implant. Both macroscopic and microscopic characteristics of dental implants could influence the success of these procedures. There were animal studies regarding to bone healing around implants  
Figure 7: Correlation between fasting glucose (FG) and HbA1c (**a**), HbA1c and %BIC (**b**), HbA1c and % bone formation (**c**). There was a strong correlation between increased HbA1c and decreased BIC (\(p<0.05\)) and decreased new bone formation (\(p<0.05\)). in diabetic models [30; 31; 32]. In hyperglycemia condition, it was found that early bone mineralization was interrupted [30], trabecular bone, signaling molecules of fibronectin and Integrin \(\alpha\)5\(\beta\)1 were reduced [31], BIC and implant removal torque were lower comparing to controls [32]. However, there are a few downsides of using animals for experiments. In case of DM, the diabetic animals might not accurately represent the pathologic condition of the T2 DM in human as animals were either drug-induced or genetically modified to create the diabetic condition. In addition, bone healing and turnover rates of these animals such as rats and rabbits are not comparable to human [33; 34]. All of these might interfere with the interpretation of the data received. Interesting, our study showed similar result of negative effects of hyperglycemia or DM on BIC and new bone formation in the implant thread indicating that bone healing capacity of T2 DM patients was significantly lower than in those healthy group. Moreover, In genetically modified and drug-induced diabetic rats, it was found that new trabecular bone around implant surfaces was reduced compared to those rats treated with insulin [31; 32] and thus presented lower removal torque values [32]. Most of our T2 DM patients were using anti-diabetic medications to control their blood glucose to a well-controlled state. However, that was not effective in increasing BIC and new bone formation around dental implants in our findings which is contradicted with what was found in the animal experiments. Another significant finding was the strong correlation between HbA1c and BIC and new bone formation.