Introduction - Materials and methods.
O. Molven, A. Halse, I. Fristad & D. MacDonald-JankowskiDepartment of Odontology - Endodontics, Radiology, School of Dentistry, University of Bergen, Norway.Introduction.
Success rates after root-canal treatment of adult teeth depend, amongst many other factors, on the preoperative diagnosis and the types of treatment, with the greatest success for pulpectomy cases and the lowest for re-treatment of endodontically treated teeth with periapical radiolucencies (Engstrom et al. 1964, Molven & Halse 1988, Sjogren et al. 1990). Although success or failure may seem clear a short time after root-canal filling, a follow-up period of at least 4 years is regarded as necessary for the conclusions on treatment results in most cases (Strindberg 1956, Reit 1987, Hepworth & Friedman 1997, Weiger et al. 1998). However, extended observation periods are needed to reveal the long-term outcome of treatment. Strindberg (1956) found that 16% of the roots with periapical radiolucencies at the start of treatment and 4%of the roots without rarefaction initially differed in diagnoses at the 4-year and final follow-up examinations, 5-10 years after treatment. There were more successes than failures evident at the later follow-up times. He questioned if there was a definite observation period after which cases could be considered as being stable.
During the last decade, attention has been drawn to the importance of the quality of coronal restorations in establishing and maintaining periapical health (Torabinejad et al. 1990, Saunders & Saunders 1994, Tronstad et al.2000).Therefore, it is possible that initially successful cases may later be recorded as failures owing to the recontamination of the root-canal system through defective temporary or permanent restorations (Siqueira 2001).
It is clear that more information is required on long term results after endodontic treatment. The outcome of endodontic treatment over an observation period of 10-17 years has been previously presented (Molven & Halse 1988). A smaller patient sample from this group has been followed for an additional10 years. The aim of the present study was to identify further periapical changes when comparing observations made 10- 17 years after root-canal treatment with the findings recorded 10 years later. Materials and methods.
One hundred and seventy-five individuals (70%) of a selected patient group who had received treatment in the School of Dentistry, University of Bergen, and had appeared for radiographic examination at a 10-17-year follow-up were traced 10 years later. They were invited to be re-examined 20-27 years after root-canal treatment. A series of intraoral exposures was obtained for 131 of these patients. Three patients were edentulous and 41 were unable to attend for various reasons. The material comprised275root fillings performed by undergraduate students 20-27 years earlier. The follow-up group
The present follow-up group of 75 roots represents some 25% of the material originally analysed at the time of treatment (Molven1976) and 48%of the material studied 10-17 years later (Halse & Molven1987, Molven & Halse 1988).The group was classified with regard to the condition at the time of root filling, the type of treatment and the technical standard of the treatment in earlier papers (Molven 1976, Halse & Molven 1987, Molven & Halse 1988). Radiographic findings.
The evaluation and classification of the periapical conditions were performed by two examiners (O.M. and A.H.) after calibration. The periapical status was first assessed separately by each examiner and classified into one of the following three groups; no disease, increased width of the periodontal space and obvious disease (Figs 1-3). Cases that had been interpreted differently by the two observers were subjected to joint re-evaluation before a decision was made. A diagnosis was not obtained for10 roots, which were rejected for technical reasons (five), surgical endodontics (four), or because the observers did not agree about the diagnosis (one). A more detailed survey of this system for the diagnosis of apical periodontitis has been given in separate papers (Halse & Molven 1986, Molven et al. 2002).
Figure 1. Normal periapical findings after endodontic treatment illustrated schematically (left) and as observed in different regions of the jaws.
Figure 2. Widened periodontal spaces illustrated schematically (left) and as observed in different regions of the jaws.
Note: The structure of the bone around the apex in the left radiograph was judged to be part of the normal trabecular system.
Figure 3. Pathological findings (periapical radiolucency) illustrated schematically (left) and as observed in different regions of the jaws.
Re-evaluation of critical cases The 265 roots left for re-evaluation were separated into two groups. One hundred and ninety-three roots, recorded with normal periapical findings on both follow-up occasions, were not subjected to further evaluation. The rest,72 roots (27% of the material), were presented to an endodontist (I.F.) and a radiologist (D.M.), who were asked to judge the status of the cases in the series of radiographs taken 10-17 and 20-27 years after treatment. A number of these cases, 58 roots in 22 individuals, had been recorded by the original observers (O.M. and A.H.) with a favourable or unfavourable change in diagnoses from 10-17 to 20-27 years, postoperatively. The rest, 14 roots in12 individuals, had been diagnosed either with periapical disease (eleven) or increased width of the periodontal membrane (three) by the same observers (O.M. and A.H.) at the two follow-up occasions.
The 72 roots were randomly grouped into two equal sets. Each set was first judged separately by each of the two additional observers and then subjected to joint discussion by the same examiners to obtain agreement about diagnosis. Two such joint evaluations were performed, one after evaluation of each set of radiographs. Thereafter, the results were compared with the findings made by the two original examiners (O.M. and A.H.). All cases judged differently by the original and additional examiners were critically re-evaluated by all four examiners during two joint meetings. The aim was consensus.
Finally, roots recorded with periapical changes at the 20-27-year follow-up were subjected to an extra joint evaluation. Direct comparisons were made between radiographs taken at the two follow-up examinations. The aim was to exclude differences in the technical standard of the images as a possible explanation of the recorded changes.
The examiners used a strict definition of periapical disease whereby only roots with periapical radiolucencies were regarded as cases with unfavourable outcome or as failures (Kvist & Reit1999, Kvist 2001). Roots exhibiting increased width of the periodontal space, often classified as uncertain cases, were the refore not included amongst the failures.
Cases with periapical changes evident at the 20- 27-year follow-up were especially examined for possible explanatory variables related to the endodontic treatment.