###### Abstract  
Bone defects may be a result of different pathologies and represent a challenge in different fields of dentistry. Techniques for the correction of bone defects involving the use of several types of grafts have been proposed. This study evaluated bone repair in rat tibiae after surgically created critical-size defects were filled with \(\beta\)-tricalcium phosphate (RTR\({}^{\text{\textregistered}}\), Septodont, FR). Critical-size bone defects were created in the tibiae of 32 male Wistar rats, which were divided into four groups (\(n=8\)): Control 30 days, Control 90 days, RTR\({}^{\text{\textregistered}}\) 30 days, and RTR\({}^{\text{\textregistered}}\) 90 days. After the experimental period, the animals were euthanized and specimens were collected, embedded in paraffin, serially cut, and stained with hematoxylin and eosin to evaluate the inflammatory and repair response. Two parameters were analyzed: neoformed bone tissue areas (NBA) and neoformed cortical areas (NCA). Statistical analysis was performed by ANOVA and Tukey's test (\(p<0.05\)). The RTR\({}^{\text{\textregistered}}\) group demonstrated superior bone healing compared with the control group in both analyzed parameters (NBA and NCA), with repair of the cortical bone and bone-tissue formation in the central region of the defect, which showed partial repair in the defect area (\(p<0.05\)). RTR\({}^{\text{\textregistered}}\) enhanced bone neoformation in the adopted experimental model and may be a useful biomaterial to boost healing in cases of critical-size bone defects. \(\beta\)-tricalcium phosphate; bone regeneration; bone substitute; RTR\({}^{\text{\textregistered}}\)  
1 March 2024  
Filled with \(\beta\)-Tricalcium Phosphate in Rat Tibiae  
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Citation: [PERSON], A.M.V. : [PERSON], C.R.E. : [PERSON], M.R.F.A.S.G. : [PERSON]; [PERSON], A.C.R. : [PERSON], [PERSON]; [PERSON], [PERSON]: [PERSON], L.T.A. : [PERSON], [PERSON]: Histological Bone-Healing Evaluation of Critical-Size Defects  
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Filled with \(\beta\)-Tricalcium Phosphate in Rat Tibiae  
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Citation: [PERSON], A.M.V. : [PERSON], C.R.E. : [PERSON], M.R.F.A.S.G. : [PERSON], [PERSON]; [PERSON], A.C.R. : [PERSON], [PERSON]; [PERSON], [PERSON]: [PERSON], [PERSON]: [PERSON], [PERSON]: Histological Bone-Healing Evaluation of Critical-Size Defects  
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Filled with \(\beta\)-Tricalcium Phosphate in Rat Tibiae
bone growth. These materials are evaluated for osteogenesis (the introduction of bone-forming cells), osteoconductivity (the support of cell proliferation), and osteoinductivity (the induction of cell differentiation into osteoblasts), with the ideal material exhibiting all three properties. However, while autogenous grafts meet these standards, biomaterials tend to exhibit strong osteoconductivity but fall short in osteogenic and osteoinductive capabilities [5; 8]. Bone substitutes are divided according to source and immune response into four categories: autogenous (obtained from the patient), homogenous (bone graft from a bone bank), heterogenous (graft from a different species), and alloplastics (produced and synthesized in the laboratory). \(\beta\)-tricalcium phosphate (\(\beta\)-TCP) is an example of an alloplastic ceramic material that has demonstrated good biocompatibility, and several studies have demonstrated its ability to stimulate bone formation by osteoconduction in the repair of bone defects [9; 10; 11; 12; 13; 14; 15; 16]. RTR(r) (Septodont, Saint-Maur-des-Fosses, France) is a bone substitute comprising \(\beta\)-TCP granules of different sizes, ranging from 500 \(\upmu\)m to 1 mm, that is used for bone-defect reconstruction in surgical procedures in dentistry [17], with satisfactory clinical and radiographic results for bone neoforformation [17; 18; 19; 20]. RTR(r) has been shown to positively influence the differentiation of osteoblasts, the expression of bone morphogenetic proteins (BMIPs), and the subsequent expression of markers critical for bone formation, such as alkaline phosphatase, type I collagen, osteopontin, and osteoclastin [18; 19].