## 4 Discussion  
After removal of the third molar, swelling causes the most discomfort for patients and is the main reason for postoperative pain [36]. Graft application did not influence the length or intensity of postoperative pain significantly, according to VAS. Compared to the control group, bone grafting resulted in a denser bone structure but impaired cortical bone formation. Bone macromorphology seems to be similar when compared to simple albumin coated allograft in other studies, although more graft remnants or sequester can be noticed when it was coated with additional gentamycin [32; 33]. Bone grafting also affected cortical bone formation. One possible explanation is that the gentamycin might have a deceleration effect on bone remodeling in the present study. When calcium sulfate is used as a carrier for gentamycin, it prolonged the hydration of calcium sulfate and adhered to the whole crystal-forming process [11]. In vivo experiments proved that gentamycin or vancomycin-coated human bone graft application in a bone defect model caused decreased healing rate and less mineralization [37; 38]. Although a study combining in vivo and in vitro approaches claimed that there is no adverse effect of gentamycin on bone-forming cells and remodeling when human bone graft is coated [39]. When other types of grafts are applied, like bovine xenograft or synthetic materials, graft remnants also occurred in the regenerated area, and its volume did not correlate with  
Figure 5: Changes of the marginal bone level (MBL) at the distal site of second molar after 1 year follow-up: (**a**) The results presented regarding to preoperative MBL loss (**b**) and to the proximity of teeth (**c**). Data are presented as mean (**a**) and mean \(\pm\) SD (**b**,**c**). Statistical significance (\(p<0.05\)) was marked by an asterisk. the healing time [2; 40]. It seems that regardless of whether we use a bone allograft, some particles of the graft cannot be resorbed. Micromorphometry analysis of CBCT images are reliable indicators of bone morphology, and its measurements correlate positively with microCT analysis of bone core biopsy samples [41]. BS/BV refers to the volume ratio of calcified tissues Po(tot) shows the total volume of open and closed pores [42]. The high value of BS/BV and Po(tot) indices reflected a higher volume and number of resorption lacunae in the control group. Tb.Th indicates the mean thickness of trabeculae. Tb.N is the total number of trabeculae per unit of length. When bone graft was applied, these indicators proved the presence of more and thicker trabeculae formation with fewer pores resulting in a denser bone structure. These results are consistent with the results of a previous CBCT study based on Tb.Th values, however the observed Po(tot) values seem to be different, which might be due to different voxel sizes were used in the two studies. [41]. The microCT data of [PERSON] et al. are positively correlated with our CBCT results in regard of Po(tot) values, which might be caused by the higher resolution of CBCT imaging in the present investigation. Albumin-coated allograft was previously investigated under similar test conditions. The values of BS/BV, Tb.Th, Tb.N and Po(tot) of that study correlate with our results, which suggests that the gentamycin component of the double-coating does not influence the microstructure of the augmented area. [33]. It seems that the double-coated allograft forms a denser new alveolar bone, like the single albumin coated allograft. Alveolar preservation is a well-known technique after tooth extraction when the further dental restoration is planned [43; 44]. Although third molars do not tend to be replaced prosthetically, the vertical ridge height protecting effect of the graft can be remarkable. In the present study, vertical ridge reduction was significantly less at the buccal cortical when the alveolar was filled in with graft. Similar results have already been observed when other teeth were removed.