Vitamin K antagonists (VKAs) (such as warfarin) and direct oral anticoagulants (DOACs) have been introduced under the title of drugs, oral anticoagulants (OACs). 1,2 VKAs exert their anticoagulation effects mainly by preventing the reduction of vitamin K to its 2-3 epoxide form (quinone). 3,4,5 The conversion of glutamate (Glu) to the Ɣ-Carbocyglutamate (Gla) form is required for the activation of coagulation factors Ⅱ, Ⅶ, Ⅸ, Ⅹ, and the reduced form of vitamin K acts as a coenzyme in this reaction. 3,4,5 Apart from coagulation factors, osteocalcin, a bone-specific protein, is very important for VKAs to modulate glutamate carbosylase by preventing the reduction of vitamin K. 3,4,6 Conversion of osteocalcin to its carboxylated form (Gla-OC) is critical for bone metabolism so that it can bind to bone hydroxyapatite and Ca+2 . 4,7 Inhibition of vitamin K through the long-term use of warfarin-derived drugs results in the production of uncarboxylated osteocalcin (Glu-OC), which has a lower affinity than the Gla-OC form, and reduced bone mass (with osteoporotic change).4,8,9 In recent years, four DOACs, the thrombin inhibitor dabigatran, factor Xa inhibitors rivaroxaban, apixaban, and edoxaban, have been approved for anticoagulation therapy. DOACs have the main advantages of showing at least equal efficacy as VKAs, not requiring blood testing for anticoagulation monitoring, and not having an important negative effect on bone metabolism.3,4,10

Osteoporosis, which causes deterioration in the internal structure (design) of the bone, as well as a decrease in bone density and quality, is a systemic skeletal disease that increases the risk of fracture and can cause morbidity and mortality.7,11 Various chronic systemic diseases and long-term drug use play important roles in the etiology of secondary osteoporosis, causing changes in bone density and microarchitecture.12,13 Long-term use of anticoagulants is often preferred in diseases and conditions such as chronic ischemic heart disease, arrhythmia, venous thrombosis, and thromboembolism prophylaxis, which are seen in the elderly population; however, the use of anticoagulants has increased recently in the younger population.

Fractal dimension (FD) analysis is used to describe the shape and structural patterns of complex units composed of many microcomponents such as trabecular bone. FD analysis can be used to analyze bone tissue using a series of box-counting algorithms. High FD values are associated with more complex microstructures.14 This technique is sufficient to evaluate trabecular healing or osteoporotic changes in jawbones.15 The Klemetti index (KI), also known as the mandibular cortical index (MCI), is a categorical method used to detect levels of cortical destruction, determine bone quality, and detect osteoporotic changes.16 The panoramic mandibular index (PMI) is a useful indicator for obtaining information about mandibular cortical bone mass.17 Panoramic radiographs are generally preferred for the evaluation of the mentioned analyses and indices.14,15,16,17 For patients using long-term oral OACs, possible osteoporotic changes should be considered when evaluating alveolar bone quality before periodontal therapy and implant surgery.3,4,5,8,9,18

As far as we know, there is no study in the literature evaluating the effect of long-term OAC use on the mandible using FD analysis. This study aimed to compare the mandibular cortical and trabecular bone structures of two different groups of patients using OACs (warfarin and DOACs) and systemically healthy patients using FD analysis and PMI, KI, radiomorphometric analysis.

The null hypothesis was that there was no difference between/among any of the radiomorphometric indices for patients using OACs and systemically healthy patients.