The results showed that the inflammatory root resorption of primary molars was related to factors such as pulpitis by caries, failure of filling, failure of root canal, pulpotomy and mandibular molars; among these, pulpitis was the riskiest factor with OR = 2669.2 and 95% CI: 579.6 - 12292.5, followed by failure of root canal with OR = 953 and 95% CI: 207.5 - 4376.66.