title: Digital radiograph registration and subtraction: a useful tool for the evaluation of the progress of chronic apical periodontitis.
abstract: The purpose of this study was to evaluate the suitability of a digital radiograph registration and subtraction software for a sensitive and reliable assessment of the progress of chronic apical periodontitis. Ninety cases of teeth with chronic apical periodontitis have been studied. In each case, a preoperative radiograph was taken, root canals were prepared, and a Ca(OH)2 paste was placed in the root canals. Radiographic control and replacement of Ca(OH)2 paste took place at 15-day intervals. The root canals were obturated 1.5 months after the first appointment. Recall radiographs were taken 0.5, 1.5, 3, 6, and 12 months after the obturation. All radiographs were taken for each case under constant conditions by using a direct digital radiography system. In each case, the preoperative, postoperative, and control and recall radiographs were digitally registered and pairwise subtracted. The resulting images were further processed by using contrast enhancement and pseudocoloring methods. Changes to the periapical tissue structure were easily detectable by using the above-mentioned methodology, even during short time intervals.
authors.affiliation: Department of Endodontology, Dental School, Aristotle University of Thessaloniki, Thessaloniki, Greece. gmicro@dent.auth.gr
authors.forename: Georgios
authors.initials: G
authors.lastname: Mikrogeorgis
authors.forename: Kleoniki
authors.initials: K
authors.lastname: Lyroudia
authors.forename: Ioannis
authors.initials: I
authors.lastname: Molyvdas
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Nikolaidis
authors.forename: Ioannis
authors.initials: I
authors.lastname: Pitas
mesh_terms: D002126:Calcium Hydroxide / Q000627:therapeutic use; D002908:Chronic Disease; D003287:Contrast Media; D018450:Disease Progression; D005500:Follow-Up Studies; D006801:Humans; D010485:Periapical Periodontitis / Q000000981:diagnostic imaging*; D010486:Periapical Tissue / Q000000981:diagnostic imaging; D011856:Radiographic Image Enhancement; D019252:Radiography, Dental, Digital / Q000295:instrumentation / Q000379:methods*; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D012389:Root Canal Obturation; D018915:Root Canal Preparation; D012984:Software; D013382:Subtraction Technique / Q000295:instrumentation
chemical_list: D003287:Contrast Media; D012387:Root Canal Filling Materials; D002126:Calcium Hydroxide