Influence of apical root resection on the biomechanical response of a single-rooted tooth: a 3-dimensional finite element analysis.
INTRODUCTION
Apical root resection is a biologically essential component in endodontic microsurgery. However, because it reduces the total root length and supported root surface, it changes the biomechanical response of the tooth. The purpose of this study was to analyze the biomechanical effect of apical root resection and to compare apical root resection with periodontal bone loss from a biomechanical standpoint.


METHODS
Finite element models of the maxillary central incisor were reconstructed. First, preoperative and surgically treated models were generated to assess the factors altering the biomechanical response of the tooth. Then, apically resected models with different amounts of resection (3, 4, 5, 6, 7, and 8 mm) were created to estimate the clinically applicable limit of apical root resection. Periodontally destructed models with varying degrees of bone loss (0.5, 1, 1.5, 2, and 3 mm) were also created to compare the effect of apical root resection with periodontal bone loss. Stress distribution, tooth displacement, and effective crown-to-root ratio (α) were analyzed for each condition.


RESULTS
Apical root resection did not significantly alter the maximum von Mises stress or tooth displacement until it reached 6 mm (α = 0.67) when the tooth was supported by normal periodontium. In contrast, periodontal bone loss had a greater impact on biomechanical response change compared with apical root resection.


CONCLUSIONS
For a tooth supported by normal periodontium, 3 mm of apical root resection (α = 1.07) appeared to be mechanically acceptable. The biomechanical influence of apical root resection was weak compared with that of periodontal bone loss.
['Jang|Youngjune|Y|', 'Hong|Hyoung-Taek|HT|', 'Roh|Byoung-Duck|BD|', 'Chun|Heoung-Jae|HJ|']
D016301:Alveolar Bone Loss D001047:Apicoectomy D001696:Biomechanical Phenomena D003198:Computer Simulation D020342:Finite Element Analysis D006801:Humans D007091:Image Processing, Computer-Assisted D021621:Imaging, Three-Dimensional D007180:Incisor D008954:Models, Biological D010485:Periapical Periodontitis D010513:Periodontal Ligament D013314:Stress, Mechanical D019228:Tooth Crown D014092:Tooth Root D014945:Wound Healing
biomechanics finite element analysis endodontic microsurgery crown-to-root ratio Alveolar bone loss apicoectomy