Purpose: Loss of crestal bone is linked to mobility. As a result, mobile teeth with receded crestal bone are not preferred as abutments and therefore are excluded from the treatment plan. The aim of this study is to find if there is real correlation between crestal bone level and tooth mobility by utilizingcone beam computedtomography and periotest. Materials and methods: The records of 67 patients who attended the dental clinics of Beirut Arab University for implant placement or orthodontic treatment between 2013 and 2014 were gathered according to the availability of CBCT ofmaxillary anterior teeth. Only 28patients of those who fulfilled the inclusion criteria responded and participated in the study. These participants were orthodontic patients with mild occlusal discrepancy who didn’t start their treatment yet, and those requesting single tooth replacement with implant prosthesis. All included participants were healthy, aging from 25 to 35 years and having good oral hygiene with acceptable functional occlusion. All permanent upper anterior teeth with fully developed roots were assessed for tooth mobility and the effect of crestal bone level by measuring thecrown root ratio. The teeth included in the study were 164upper anterior teeth obtained from the 28 CBCTs. The data was coded and entered using the statistical package SPSS version 20. The data was summarized using descriptive statistics. Results: The mean crown root ratio was (0.6461) and mean periotest reading was (0.0734). The maximum crown root ratio was 1.52 and the minimum was 0.35, with a median of 0.6159and standard deviation of 0.14710. The maximum periotest value was 22.47 and the minimum was -5.50 with a median of -0.3167and standard deviation of 3.04773.Using SPSS, we get: r = 0.653. Pearson’s correlation coefficient revealed a statistically significant moderate and positive correlation between crown root ratio and tooth mobility at 0.01 level. Keywords: Tooth mobility, Crestal bone level, Crown root ratio, CBCT, Periotest.