Increased width of the apical periodontal membrane space in endodontically treated teeth may represent favourable healing

Aim To examine cases showing increased width of the periodontal space (IW) at a long-term follow-up examination and to determine whether this finding could be explained by endodontic or nonendodontic factors. Methodology A series of intraoral radiographs was obtained from 131 patients 20-27 years after root canal treatment. The same individuals had been examined 10 years earlier, and radiographs taken immediately after treatment were also available. Fourteen roots (5.6%) demonstrated increased width of the apical periodontal space at the end of the study period. These were subjected to further analysis in an attempt to disclose possible explanatory factors. Results Two of the 14 cases had reduced marginal bone levels interpreted as the origin of the IW. In three cases, overextended root filling material present 10 years earlier had disappeared and the persistent IW was interpreted as representing a remodelling process, In six cases the findings were explained as being caused by physical and anatomical factors that represented healing without complete re-formation of the apical periodontal structures, or both. Three cases were judged as unfavourable, on the basis of lacking progress in healing, unsatisfactory obturation of the apical portion of the root canal or dentine resorption close to the apical end of the root filling. Conclusion Most of the 14 IW cases examined after 20-27 years could be explained by reduced marginal bone support, or by physical and anatomical factors or they might represent incomplete reformation of the typical apical morphology and were thereby recorded as favourable outcomes.