Influence of intracanal post on apical periodontitis identified by cone-beam computed tomography

Influence of intracanal post on apical periodontitis identified by cone-beam computed tomography     Carlos EstrelaI; Mike Reis BuenoII; Olavo César Lyra PortoI; Cleomar Donizeth RodriguesI; Jesus Djalma PécoraIII IDental School, Federal University of Goiás, Goiânia, GO, Brazil IIDental School, University of Cuiabá, Cuiabá, MT, Brazil IIIDental School, University of São Paulo, Ribeirão Preto, SP, Brazil Correspondence     ABSTRACT The determination of the success of endodontic treatment has been often discussed based on outcome obtained by periapical radiography. The aim of this study was to verify the influence of intracanal post on apical periodontitis detected by cone-beam computed tomography (CBCT). A consecutive sample of 1020 images (periapical radiographs and CBCT scans) taken from 619 patients (245 men; mean age, 50.1 years) between February 2008 and September 2009 were used in this study. Presence and intracanal post length (short, medium and long) were associated with apical periodontitis (AP). Chi-square test was used for statistical analyses. Significance level was set at p<0.01. The kappa value was used to assess examiner variability. From a total of 591 intracanal posts, AP was observed in 15.06%, 18.78% and 7.95% using periapical radiographs, into the different lengths, short, medium and long, respectively (p=0.466). Considering the same posts length it was verified AP in 24.20%, 26.40% and 11.84% observed by CBCT scans, respectively (p=0.154). From a total of 1,020 teeth used in this study, AP was detected in 397 (38.92%) by periapical radiography and in 614 (60.19%) by CBCT scans (p<0.001). The distribution of intracanal posts in different dental groups showed higher prevalence in maxillary anterior teeth (54.79%). Intracanal posts lengths did not influenced AP. AP was detected more frequently when CBCT method was used. KeyWords: apical periodontitis, cone beam computed tomography, root canal obturation, intracanal post, endodontic success. RESUMO O objetivo deste estudo foi determinar a influência de retentores intraradiculares na periodontite apical (PA), detectados por radiografia periapical (RP) e tomografia computadorizada de feixe cônico (TCFC). Um total de 1.020 imagens, tomadas de 619 pacientes (245 homens, idade média de 50,1 anos), entre Fevereiro de 2008 e Setembro de 2009, foram avaliadas. A presença e o comprimento de retentores intraradiculares (curto, médio e longo) foram associados com a PA. Os dados foram estatisticamente avaliados empregando-se os testes Qui-quadrado e o Kappa. Três observadores avaliaram todas as imagens, considerando-se a presença de retentor intraradicular, seu comprimento e a PA. De um total de 1.020 dentes analisados no estudo, a PA foi detectada em 397 (38,92%) usando RP e em 614 (60,19%) usando TCFC (p<0,001). Em 591 retentores intraradiculares, nos diferentes comprimentos (curto, médio, longo) foram observadas PA usando RP em 15,06%; 18,78% e 7,95%, respectivamente (p=0,466). Considerando os mesmos comprimentos de retentores foram observados PA em 24,20%; 26,40% e 11,84% por meio de TCFC, respectivamente (p=0,154). A distribuição de retentores nos diferentes grupos dentários mostrou elevada prevalência em dentes anteriores superiores (54,79%). Os retentores intraradiculares não influenciaram a PA e as TCFC detectaram mais freqüentemente a periodontite apical.     INTRODUCTION The success of endodontic treatment is related to the elimination of etiologic factors of periapical problems from the root canal system allied to a hermetic sealing by filling material with excellent physical and biological properties (1). The knowledge of all implications involved with endodontic treatment, clinical factors or apical periodontitis (AP) is essential to choose between the preventive actions or the therapeutic protocol (2). AP is a consequence of root canal system infection, which can involve progressive stages of inflammation and changes of periapical bone structure, resulting in resorption identified as radiolucencies in radiographs (3), which corresponds to a two-dimensional aspect of a three-dimensional structure (4). Periapical radiography is habitually used for diagnosis, treatment planning, and follow up endodontic treatment, and its benefits and limitations should be well-known (3-5). The prevalence and risk factors of AP in 1,372 periapical radiographs of endodontically treated teeth in a selected population of Brazilian adults was recently studied (2). The quality of root filling, status of coronal restoration and presence of posts associated with AP were analyzed. The findings of the present investigation showed that the prevalence of AP was low when associated with high technical quality of root canal treatment. Poor coronal restoration increased the risk of AP even when endodontic treatment was adequate. The presence of intracanal posts had no influence on the risk of AP based on two-dimensional aspects offered by periapical radiographs. Holland et al. (1) reported that the marginal coronal leakage after post space preparation is an expressive problem for endodontic treatment and all efforts should be directed to its elimination. Specific studies addressing this issue are very important to improve the understanding of the problem and possibilities of resolution. The functional restoration of the tooth may involve the necessity of root canal treatment associated with or without intracanal post, with function of re-establishment the dental structure lost. Kvist et al. (6) determined the relation between technical quality of root filling seal in teeth with posts and radiographic status of the periapical tissues. Periapical radiolucencies were judged to be present in 16% of roots with posts and in 13% of roots without posts. Roots with posts in which the remaining root filling was shorter than 3 mm showed a statistically significant higher frequency of periapical radiolucencies. It was found that an improper seal was more unfavorable in roots with posts. The findings of this study indicate that the placement of a post will not per se decrease the probability of periapical healing. It also suggests that the remaining root filling must not be shorter than 3 mm. On the other hand, in view of recent technological advances some concepts of endodontic would be reconsidered, specially after new imaging modalities had been added to dental radiology as viable diagnostic tools, namely digital radiography, densitometry methods, cone-beam computed tomography (CBCT), magnetic resonance imaging, ultrasound, nuclear techniques (5,7,8). Some diagnostic tools, like CBCT scan providing detailed high-resolution images of oral structures and allowing early detection of bone lesions with view in three dimensions. CBCT has been used for several clinical and investigational purposes in endodontics (5,8-11). Estrela et al. (5) evaluated the accuracy of CBCT images, (...truncated)