Klinische Erfolgsrate von endodontischen Revisionsbehandlungen im studentischen Behandlungskurs - eine retrospektive Studie -

The aim of this study was the retrospective evaluation of endodontic retreatments, which were carried out by undergraduate dental students in the Department of Restorative Dentistry, Philipps-University of Marburg between 2004 and 2007. Success was defined as the absence of symptoms and radiolucency (PAI ≤ 2) at follow-up. The evaluation of postoperative radiographs were graded by two independent, calibrated examiners (κ=0,812-0,975). A total of 120 patients with 133 endodontically retreated teeth (219 roots and 267 root canals) comprised the study population. The patients’ age ranged from 16 to 83 years. Slightly more male (53.4%) than female patients (46.6%) were treated. The retreated teeth were nearly evenly distributed to both jaws. Significantly less anterior teeth (24.8%) than posterior teeth (75.2%) were subject to endodontic retreatment. Based on the number of teeth re-examined, a recall rate of 77.2% (n=95) was achieved in the present study. 28 treated teeth (46 roots and 55 root canals) could not be followed-up (dropout) due to various reasons. In 10 cases, the teeth had been extracted. The exclusion of these cases seemed useful for the calculation of the recall rate. The determined over-all success rate was 75.2%. By excluding the previously known cases of extraction (n=10), an overall success rate of 83.2% could be recorded. Persistence of the preoperative periapical lesion was observed in 14 patients. However, three of those cases showed such an advanced stage of healing (PAI score <, completely asymptomatic), that a relative success ("functional") was defined. Thus, there was a relative success rate of 86.4%. It was found that failure was most frequently observed in second premolars. Overall, more posterior (n=19) than anterior teeth (n=4) failed. The gender comparison showed that a success was more likely to be recorded in female than in male patients. Neither age (p=0.129) nor gender (p=0.217) significantly affected success or failure of endodontic retreatment. In 54.7% (n=52) of the cases, an indirect restoration could be found at follow-up. The type of restoration had no statistical significance on the final result of treatment (p=0.068). Further, there was no statistical significance in terms of coronal radiographic status (RCS score), which reflects the quality of an existing restoration - as far as radiographically assessible. However, the coronal radiographic status (RCS score) differed significantly in the before and after comparison (p=0.017). Regarding the length of the root canal filling (LRF score; over- and underfilling of the root canal system), there was a statistically significant influence (p=0.012) on the treatment result. The absolute figures showed that, compared to the radiographic baseline, the percentage of short root canal fillings could be reduced significantly (p<0.001) from originally 60.9% (n=81) to finally 18.9% (n=18). In 71.6% (n=68) of the followed-up cases, the root canal filling ended 0-2 mm from the radiographic apex, as requested by the literature. The percentage of homogeneously filled root canals (grade 1) was 82.1% (n=78) at follow-up and showed a significantly higher value in comparison to the radiographic baseline (24.8%, n=33). The effect of homogeneity or compaction of the root canal filling (HRF score) was significant (p=0.001) for treatment outcome. The quality of the root canal filling (RF score) also demonstrated a statistically significant impact on the success or failure of endodontic retreatment (p=0.019). The proportion of teeth, which were evaluated with RF score grade 5 (poor quality) at follow-up, amounted to only 3.2% (n=3) and was therefore vanishingly small in relation to the radiological baseline (69 (51.9%) RF score grade 5 teeth). 88 (83.8%) of the 105 evaluated teeth showed a periapical radiolucency at baseline. While the failure rate amounted to 26.1% in cases with preoperative periapical radiolucency, it was only 17.6% in cases without periapical radiolucency. A significant influence on the outcome of treatment could not be attributed to this parameter (p=0.458). In conclusion, this study demonstrates that factors such as the “length”, “homogeneity” and “quality of root canal fillings” can influence the results of endodontic retreatment significantly and is therefore in accordance to existing literature. The results of the factors “quality of restoration” and “periapical status” can not be explained conclusively with the existing literature. Deductively, the treatment results achieved by undergraduate students at the Department of Restorative Dentistry, Center for Dental, Oral and Maxillofacial Surgery, Philipps-University of Marburg, can be considered a long-term tooth-preserving therapy.