## 4 Discussion  
In this study, 82 periodontal lesions with bone defects in 80 patients were analyzed radiographically. The significance of the location of the lesion in the jawbone, the type of graft material, and the type of intraosseous defect were examined. The results revealed no significant difference in bone volume between the function involvement group and the intrabony defect group. Therefore, a \(t\)-test assuming equal variance indicated that there was no statistically significant difference in the amount of bone growth based on the type of intraosseous defect. Additionally, when the location of the intraosseous lesion was divided into two groups, there was no difference in variance between the groups. A \(t\)-test assuming equal variance also demonstrated no statistically significant difference in the amount of bone fill between the two groups. There was not sufficient variation in bone graft materials or an adequate number of cases for each graft material to make a significant comparison. However, no graft material yielded significantly different results. This challenges the widely held theory that bone grafts or bone substitute grafts, such as demineralized freeze-dried bone allograft, possess unique osteoinductivity. Instead, it seems these materials primarily enhance wound stability within the defect, serving as a provisional matrix or scaffold. In a 1999 study by CR Richardson et al. [18], GTR in humans using Bio-Oss\({}^{\circledR}\), a bovine-derived xenograft, and demineralized freeze-dried bone allograft showed no statistically significant difference in radiographic bone fill between the two graft groups. Numerous bone substitute grafts have been compared until recently. In a 2019 study [19] by S Oh. et al., GTR with deproteinized bovine bone mineral (DBBM) and collagen membrane, and periodontal regeneration with collagen-containing DBBM alone, produced similar radiographic bone fill results. In 2023, Lee, J.H. et al. [20] compared GTR for severe class II furcation defects in the mandibular molar using porcine-derived soft block bone and porcine-derived particulate bone substitutes, respectively, and found no significant difference in radiographic bone fill. For furcation involvement, the \(t\)-test also demonstrated no significant difference in the amount of bone fill when the location of the lesion was dichotomized into the upper and lower jaw. This finding contradicts a previous study by Tonetti et al. (1993), which suggested that maxillary fraction lesions would not respond more effectively to GTR than mandibular fraction lesions [17]. The hypotheses positing a greater bone regeneration effect in GTR in the mandible than in the maxilla and a greater bone-filling effect in periodontal lesions without furcation area involvement than in lesions with furcation involvement, as advocated in the 1971 article by Ellegaard et al. and the 1993 article by Tonetti et al., were rejected in this study [17; 21]. However, these results would be applicable if the internal debridement and root surface treatment of the defect were performed to the same degree in each case. The anatomy of maxillary molars is more likely to be trifurcated compared to mandibular molars, greatly limiting instrumental access to the furcation entrance [22]. Successful regeneration of periodontal tissue occurs only in the absence of residual epithelial or granulation tissue or a complete couch of calculus debris and pathologic chalky material that may interfere with regeneration. To achieve this, preoperative computed tomography is recommended to determine the morphology of the defect and predict the flap design and necessary instrumentation. During the course of this study, only radiologic evaluation of the teeth was possible, making it impossible to classify the Glickman or Hamp grade of the furcation lesion. Pontoriero's study [23] demonstrated that 100% horizontal defect fill could be achieved in mandibular Glickman grade 2 fraction involvement lesions.