Objective: To determine the occurrence of third molar agenesis and associated factors in patients at an outpatient dental clinic in Morelos, Mexico. Materials and methods: Cross-sectional design based on a series of 295 digital panoramic radiographs, selected through consecutive sampling and evaluated using CS Imaging® software (Carestream Dental, Atlanta, GA, USA). Binary logistic regression analysis was performed using the SPSS v. 24 statistical package (IBM Corp., Armonk, NY, USA) to calculate odds ratios and 95% confidence intervals between agenesis and explanatory factors. Results: Agenesis was more prevalent in the maxillary third molars, with 59.3% (n = 175) in tooth 18 and 53.9% (n = 159) in tooth 28. In contrast, mandibular third molar agenesis was less frequent, with 46.8% (n = 138) in tooth 38 and 45.8% (n = 135) in tooth 48. The absence of two molars showed the highest occur...