Results
A total of 48 samples were prepared. Samples found to have defects in the pre-application scanning images during micro-CT analysis were excluded from the study. The number of samples in the sodium bicarbonate group decreased to 15, in the glycine group to 12, and in the erythritol group to 14.
Defect depth
The mean defect depth values of sodium bicarbonate, glycine, and erythritol groups on enamel and cementum surfaces were shown in Table 1. The mean defect depth on enamel and cementum surfaces in the sodium bicarbonate group was observed significantly greater than the erythritol and glycine groups at both power settings (p <0.05, Table 1). There were statistically significant differences between the erythritol and glycine groups on enamel surfaces (p <0.016). The mean defect depth in the glycine group was greater than the erythritol group. At a medium power setting, the mean defect depth in the erythritol group on the cementum surfaces was observed significantly greater than a glycine group (p <0.016). At maximum power setting, on cementum surfaces, no statistically significant difference was observed between the glycine and erythritol groups (p >0.016). The mean defect depth at the maximum power setting was significantly higher than at the medium power setting in all groups (p <0.05, Table 1). There were no statistically significant differences between the mean defect depth on enamel and cementum surfaces in the glycine group (p >0.05).
Defect volume
The mean defect volume values of sodium bicarbonate, glycine, and erythritol groups on enamel and cementum surfaces were shown in Table 2. At both power settings, there were no statistically significant differences between the mean defect volume on enamel surfaces in the erythritol and glycine groups and the erythritol and sodium bicarbonate groups (p >0.016). The glycine group had significantly less mean defect volume than the sodium bicarbonate group (p <0.016). The mean defect volume at the maximum power setting was significantly higher than at the medium power setting in all powder groups (p <0.05, Table 2) whereas the erythritol group had significantly less mean defect volume than the sodium bicarbonate group (p <0.016). At maximum power settings, the mean defect volume on enamel surfaces was significantly lower than the mean defect volume on cementum surfaces in all groups (p <0.05)
Demineralization depth
The mean demineralization depth values of sodium bicarbonate, glycine, and erythritol groups on enamel and cementum surfaces were shown in Table 3. At both power settings, no statistically significant differences were observed between the mean demineralization depth on enamel surfaces in all groups (p >0.05, Table 3). Also, at a medium power setting, no statistically significant differences were observed between the mean demineralization depth on cementum surfaces in all groups (p >0.05, Table 3). The mean demineralization depth at the maximum power setting was significantly higher than at the medium power setting in all powder groups (p <0.05, Table 3).
Tissue mineral density (TMD)
The mean TMD values of sodium bicarbonate, glycine, and erythritol groups on enamel and cementum surfaces were shown in Table 4. No statistically significant differences were observed between the mean TMD values of the samples in all groups before the application (p >0.05, Table 4) while the mean TMD in the sodium bicarbonate group had significantly greater than the mean TMD in the erythritol and glycine groups after the application (p <0.05, Table 4). In all groups, the mean TMD after the application was significantly less than the mean TMD before the application (p <0.05, Table 4).