Factors associated with healing of periradicular lesions

Abstract: Healing of periradicular lesions is a complex process. This thesis addressed some factors of importance to the outcome, namely treatment options and host response in cases of refractory lesions, levels of pro-inflammatory and antiinflammatory cytokines in the inflammatory lesions and the response of the cytokines to preoperative administration of antibiotics. Thirty-seven subjects with nonhealing periradicular pathoses were randomised to either endodontic retreatment or surgery. Comparison of clinical and radiographic evaluations of outcomes after one year disclosed no significant difference between the treatments. Ten subjects with endodontically untreated teeth with periradicular pathoses underwent root-end surgery. At the one-year follow-up, radiographic examination showed complete or incomplete healing in five cases and uncertain healing in the remainder. However, viable bacteria were recovered from the root canals of nine of ten teeth Both pro-inflammatory and anti -in fl ammatory cytokines are implicated in the pathogenesis of periapical lesions. Twenty-five teeth were root-end resected and the periapical lesions were retrieved. TGF-beta1 was recovered from 21 lesions: the remaining four lesions, with no TGF-beta1 activity, were diagnosed as scar tissue. In the final study, 22 subjects with root-filled teeth with refractory lesions were randomised into a control group, or an antibiotic group given a five day preoperative course of linezolid. One tooth from each subject was root-end resected. The cytokines IL- Ira, IL-6 and TGF-01 were quantified in periapical tissue extracts. The antibiotic treatment group exhibited significantly lower levels of IL-1ra. Main conclusions: The choice of surgery or endodontic retreatment of refractory lesions should be based on careful consideration of the individual case. Surgery alone is not sufficient for elimination of bacteria in untreated infected root canals. With endodontic treatment, it is possible to achieve a bacteria-free root canal and this may prove mandatory for long- term success. The anti-inflammatory cytokine TGF-01 is present in measurable amounts in periapical lesions and may be a marker of the severity of the periapical inflammation. The cytokine IL- Ira may be a sensitive marker of the effect of antibacterial treatment on the severity of inflammation in periapical tissues.