The aim of this study was to assess the effect of the quality of the coronal restoration and the root filling on the success of endodontic treatment. Patients treated at Kuwait University Dental Clinics (KUDC) from 2003 to 2014 were contacted by telephone calls. Demographic data and clinical records of patients, including age, gender, the tooth number, and medical history were recorded. Each patient received clinical examination for all teeth, including assessment of the coronal filling (type, quality), root- and/or coronal fracture, and the periodontal condition around the tooth (e.g., probing depth, gingival recession); percussion and mobility tests. A periapical radiograph of the endodontic treated tooth was taken to determine the health of the periapical tissues using the periapical index. The quality of the root filling was assessed by length and density of the root filling. The mean follow-up period was 4.8 years. The overall success rate of endodontic treatment was 86%; teeth without any initial periapical lesion had a success of 93%, whereas those with such lesion had a success rate of 80%. Periapical healing was not significantly associated with either the length of root filling (p = 0.40) or the density of root filling (p = 0.099), but was statistically significantly associated with the presence of coronal filling defects (p = 0.001). This study demonstrated that inadequate coronal filling but not the quality of root filling was associated with a higher prevalence of periapical lesions.
Keywords: apical periodontitis; coronal filling; periapical index; root filling.