###### Abstract  
In the literature, there are no studies evaluating alveolar bone width in areas with a single missing tooth in terms of orthodontic tooth movement. This study was meant to determine whether residual alveolar bone width in dentulous crests is a risk factor for orthodontic tooth movement. The aim of this study was to evaluate the change in the residual alveolar bone width in the edentulous region compared to the alveolar bone width on the symmetrical toothed side using CBCT in individuals with a single missing tooth in whom orthodontic tooth movement was planned. This retrospective radiographic study was performed using CBCT images that were taken before orthodontic treatment for the evaluation of the edentulous area between January 2010 and January 2022. Individuals without any systemic disease aged 18 years or older whose edentulous area was restricted to one tooth were included in this study. Bone measurements were made on cross-sectional CBCT images. Of the 265 individuals participating in this study, 129 were male and 136 were female, with a mean age of 32.67 \(\pm\) 6.50 years. The distribution of 265 edentulous regions (caused by 265 tooth extractions) was as follows: 23 were in the incisor region, 54 were in the premolar region, and 188 were in the molar region. The molar region had the highest bone width among the edentulous regions (\(p\) < 0.01). Bone widths were smaller in the edentulous crests for all regions (\(p\) < 0.01). In this study, it was determined that the bone width in the areas with a single missing tooth was insufficient, and this is a risk factor for orthodontic treatment. orthodontic treatment; alveolar bone width; missing tooth; insufficient bone width; CBCT 2023 13241. 13241. Some patients may accept neither conventional prosthetic therapy nor implant-supported prosthetic therapy. Orthodontic treatment comes into play in the restoration of missing teeth in this patient group [4]. Tooth extraction is preferred in individuals with skeletal class 1, class 2, and class 3 malocclusions and moderate-to-severe crowding. Tooth extraction may also be preferred for camouflage treatment in skeletal class 3 individuals. In orthodontic tooth extraction, since tooth movement begins immediately after extraction, alveolar resorption at the extraction site remains minimal. However, in the presence of a pre-existing tooth deficiency in individuals with this malocclusion, it is likely that the alveolar bone width in the region will decrease due to resorption. Within one year after tooth extraction, the alveolar bone undergoes approximately 50% resorption [5]. Hence, it is clear that alveolar bone width is a risk factor in individuals with tooth deficiency. Today, implant-supported prosthetic rehabilitation is generally considered the first treatment option for individuals with a single missing tooth. Implant surgery planning includes routine assessment of the width and height of the alveolar bone in the area of the missing tooth. Deficiencies in alveolar bone width and height will necessitate advanced implant surgical techniques and complicate the procedures. Even if other fixed restorations are planned instead of implant-supported prostheses in these individuals, insufficient bone width, height, and volume will still cause aesthetic problems [6]. Cone beam computed tomography (CBCT) is an imaging method that has increased in popularity in dentistry in recent years [7]. Although its use has been restricted due to radiation dose and cost, it is used in cases where conventional radiographs are inadequate because it creates three-dimensional images and gives real measurements [8; 9]. The introduction of CBCT in dentistry has rapidly changed the diagnostic capacity and provided dentists with the opportunity to make three-dimensional diagnoses [7]. Current CBCT units provide excellent high-resolution, three-dimensional imaging of the anatomy of bones in the head and neck region. It has made dental implant planning and surgical placement simple and reliable.