Effect of length of apical root resection on the biomechanical response of a maxillary central incisor in various occlusal relationships

Abstract

Aim To investigate the stress distribution and tooth displacement of a maxillary central incisor with various apical root resection lengths and occlusal relationships using finite element (FE) analysis. Methodology A maxillary central incisor was scanned by micro‐CT. First, the FE intact incisor model with dentine, enamel, pulp and root surrounded by alveolar bone and periodontal ligament was designed based on the micro‐CT image data. Then, six FE models with varying lengths of apical root resection were established to simulate the clinical treatment and reveal the clinically applicable limit of apical root resection during endodontic microsurgery. For each model under different loading conditions, the maximum von Mises stress (σ max) at the root apex, root cervix, alveolar bone and periodontal ligament and the maximum tooth displacement (ΔR max) were calculated and compared. Results In a normal occlusion, more than 6 mm of root resection resulted in a marked increase in the ΔR max values (>10%) and σ max values of alveolar bone (>50%); the stress levels at the root apex increased dramatically when the apical root was resected more than 7 mm. With increased overjet, apical root resection did not change the stress level markedly until it reached 8 mm, but the ΔR max increased markedly (>10%) if the root was resected more than 5 mm. With deep overbites, the σ max increased significantly (>50%) when the root was resected more than 4 mm whilst the ΔR max decreased. With increased overjet and deep overbite, more than 6 mm of resection resulted in a substantial σ max increase (>50%) of alveolar bone and the ΔR max increased markedly (>10%) when the root was resected 8 mm. Additionally, the σ max and the ΔR max values were greater with increased overjet and lower with deep overbites. Conclusions Using FE analysis, apical root resection of more than 6 mm resulted in a marked increase of stress distribution and tooth displacement in normal and increased overjet with deep overbite occlusal relationships. In increased overjets or deep overbites, more than 5 mm or 4 mm, respectively, stress distribution and tooth displacement increased markedly.

Decision Support for Removing Fractured Endodontic Instruments: A Patient-Specific Approach

“…As a perspective, this patient-specific stress analysis could also lead the root-end preparation to be customized and the tip size to be adapted according to the anatomy of each root [36]. Regarding the resection level, a 3 mm apicoectomy presents lower stresses than 6 mm, which is in accordance with previous FEA studies [9,37]. However, Von Mises stress was herein used as a failure criterion under the assumption that dentin could fail after plastic deformation and distortion [38].…”

Impact of Periodontal Attachment Loss on the Outcome of Endodontic Microsurgery: A Systematic Review and Meta-Analysis

“…The main causes for root canal treatment failure include extraradicular infection, foreign body reaction, and root canal system persistent infection caused by complex anatomical structures at the periradicular area and periradicular cysts. However, several iatrogenic factors may also be related to post-treatment endodontic disease, such as root perforation, ledge formation, instrument fracture and overfilling [ 4 , 5 ].…”

“…Endodontic microsurgery (EMS) aims to eradicate the sources of infection once the apical root resection removes most of the infected anatomical structures and repairs potential procedural errors in the apical region [ 4 , 11 ]. This surgical procedure is characterized by the use of an operating microscope which improves illumination and magnification, thus allowing to meticulously identify apical anatomy and examine the resected root surface [ 6 , 7 , 13 ].…”

“…In either scenario, EMS decreases root length, thus altering the crown-to-root ratio (CRR) and periodontal support. Also, this procedure modifies the tooth’s biomechanical response, causing unfavorable stress distribution and increased tooth mobility, which may influence tooth function and survival as it remains exposed to continuous occlusal loading [ 4 , 25 ]. Periodontal bone loss also aggravates CRR, simultaneously increasing the clinical crown length and decreasing the supported root area.…”

“…Periodontal bone loss also aggravates CRR, simultaneously increasing the clinical crown length and decreasing the supported root area. Since the functional stress is mostly concentrated on the cervical root third, periodontal bone loss has a greater influence on biomechanical parameters than the apical root resection itself [ 4 , 24 , 25 ]. Moreover, as mentioned above, patients’ occlusion also impairs tooth stability after EMS.…”