## 1 Introduction  
Tooth extraction results in changes of the alveolar bone dimensions; these changes occur over time in vertical and horizontal directions in different proportions [1; 2]. Studies have shown that the bone contours change from the first 60 to 90 days after extraction [1; 2] and that the bone loss is higher vertically than horizontally [1; 2; 3]. It has been noted that horizontal bone resorption can reach up to 57%, and the amount of lingual bone reduction could amount up to 30% [4]. To compensate for these dimensional changes, various biomaterials are used for bone regeneration; autogenous bone, non-protein type of materials close to human bone, natural and synthetic biomaterials, and even ground teeth can be used as bone grafts [5; 6; 7; 8; 9]. Other approaches, like the application of natural substances (apigenin and melatonin), can stimulate bone formation in areas with bone defects [10; 11; 12]. In several articles, it has been stated that melatonin is an essential mediator in the ability to stimulate and form new bone [13; 14; 15]. It has been observed that melatonin puts on the production of type I collagen [16]. Melatonin can also inhibit the bone reabsorption by regulating the formation and activation of osteoclasts mediated by RANK-L (nuclear factor receptor activator of the kappa-B ligand) [17]. Therefore, melatonin could be considered for treatments where an enhanced formation of bone is required [18; 19; 20; 21; 22]. The oral cavity is affected by a number of conditions such as mucositis, tooth decay, periodontitis, and cancers, which affect the oral cavity normally. However, the use of melatonin has been observed to enhance implant osseointegration, bone regeneration, and can also help in the management of periodontitis [23; 24; 25; 26; 27; 28; 29; 30]. Today, there are many natural products that play a significant role in medicine, and many essential substances from plants, such as flavonoids, help as medicine for cancer [31]. Flavonoids, found in vegetables, fruits, and plants, are natural compounds with health benefits such as creating new bone and reducing its resorption [32; 33; 34; 35]. Among the flavonoids, apigenin compounds seem to stimulate the proliferation of osteoblasts, thus preventing osteoporosis based on their antioxidant activity [32; 33; 34; 35]. According to some animal studies, other flavonoids can reduce bone resorption in ovariectomized rats. Osteolastogenesis has also been shown to be reduced by controlling the factor-kappa \(\beta\) and a protein activator (AP-1) in humans [36]. It has been demonstrated that naringenin interferes in osteoclastogenic processes by inhibiting the osteoclasts from differentiating and, thus, reduces bone resorption [36; 37]. Apart from bone resorption by osteoclasts, apigenin induces cellular apoptosis of osteoclasts, and other beneficial effects reported in cancer, Alzheimer's disease, amnesia, depression, insomnia, and diabetes [38; 39; 40]. It possesses remarkable anti-inflammatory, antioxidant, and osteogenic properties [41]. In addition, apigenin has antimicrobial activity, and resveratrol helps apigenin to bypass hepatic metabolism and maintain apigenin's anti-inflammatory activities in the body [42; 43]. The aim of our study is to evaluate the capacity of apigenin K and melatonin to stimulate the bone regeneration process after teeth extraction at 1, 2, and 3 months follow-up.