## 4 Discussion  
This clinical study was designed with two control groups (FDBA/CM and RCP) to verify whether A-PRF or a combination of liquid PRF and FDBA covered by A-PRF would have an additive benefit in maintaining bone in ALP procedures in current heavy smokers. The bone volumes were measured vertically and horizontally at three different levels (horizontal 1 mm, horizontal 3 mm, and horizontal 5 mm) using two CBCT images before extraction and at six months after grafting, and the bone vitality and quality were assessed through histological analysis. Regarding the bone volume, the A/S-PRF group showed no statistically significant reduction in any of the four outcome variables (vertical height, horizontal 1 mm, horizontal 3 mm, and horizontal 5 mm) from baseline to six months, while the A-PRF group showed statistically significant reductions for two outcomes (vertical height and horizontal 5 mm). Both the FDBA/CM and RCP groups showed statistically significant reductions in all four outcomes, showing the lowest ability among the study groups in the maintenance of bone volume compared to baseline. Histological analysis revealed similar bone quality for both PRF groups (A-PRF and A/S-PRF) and the negative-control (RCP) group after six months, with completely vital bone; however, in the RCP group, a considerable amount of fibrofatty bone marrow was observed, while the positive control (FDBA/CM) resulted in a mixture of both vital and non-vital bone. This can be explained by a reduction in blood supply during the bone formation process, which is exacerbated in cases of smoking. There is still a debate about whether the use of PRF provides an advantage compared to the use of bone grafting alone for bone regeneration [36; 37]. However, the present findings suggest that it is justifiable to use it in alveolar ridge preservation, as it was able to maintain the alveolar ridge dimensions and generate vital bone. There are no previous studies that have evaluated the efficacy of PRF in alveolar ridge preservation among smokers; however, multiple studies have investigated the use of PRF in non-smokers, the outcomes of which agree with those of the current study regarding bone regeneration. In one clinical trial where the authors compared PRF with FDBA, they reported that both groups  
Figure 4: A-PRF group (**A**,**B**): Mature lamellar bone can be observed, with many osteocytes residing in the lacunae, while fibrovascular bone marrow is observed at the periphery (hematoxylin–eosin; original magnification; (**A**) \(\times\)10; (**B**) \(\times\)20). A/S PRF group (**C**,**D**): Mature lamellar bone can be observed, with many osteocytes residing in the lacunae. The fibrofatty marrow contains scattered inflammatory cells (**C**). Osteoblastic rimming (arrow) (**D**) (hematoxylin–eosin; original magnification; (**C**) \(\times\)10; (**D**) \(\times\)20). FDBA/CM group (**E**,**F**): A mixture of mature vital and non-vital bone tissue. The non-vital bone grafted bone is present in the center and surrounded by vital bone (arrow) (**F**) (hematoxylin–eosin; original magnification; (**E**) \(\times\)10; (**F**) \(\times\)20). RCP group (**G**,**H**). Mature/vital bone embedded in a fibrofatty marrow (**G**). Higher magnification to show the fatty bone marrow (**H**) (hematoxylin–eosin; original magnification; (**G**) \(\times\)10; (**H**) \(\times\)20). showed significant maintenance of the ridge volume after twelve weeks compared to the baseline; however, there were no statistically significant differences between the two study groups [38]. Another clinical trial examined four unique treatment options--A-PRF, A-PRF + FDBA, and FDBA--and a normal blood clot and found that A-PRF + FDBA resulted in the lowest loss in alveolar ridge volume, while A-PRF performed similarly to FDBA, and the blood clot resulted in the worst outcome. In terms of vital bone formation, both PRF groups showed superior results when compared to FDBA and the blood clot group [39].