ABSTRACT
Objective The purpose of this study was to evaluate, by using finite element analysis, the influence of post location and occlusal loading location on the stress distribution pattern inside the root canals of the mandibular 1st molar. Material and Methods Three different 3-D models of the mandibular 1st molar were established: no post (NP) - a model of endodontic and prosthodontic treatments; mesiobuccal post (MP) - a model of endodontic and prosthodontic treatments with a post in the mesiobuccal canal; and distal post (DP) - a model of endodontic and prosthodontic treatments with a post in the distal canal. A vertical force of 300 N, perpendicular to the occlusal plane, was applied to one of five 1 mm2 areas on the occlusal surface; mesial marginal ridge, distal marginal ridge, mesiobuccal cusp, distobuccal cusp, and central fossa. Finite element analysis was used to calculate the equivalent von Mises stresses on each root canal. Results The DP model showed similar maximum stress values to the NP model, while the MP model showed markedly greater maximum stress values. The post procedure increased stress concentration inside the canals, although this was significantly affected by the site of the force. Conclusions In the mandibular 1st molar, the distal canal is the better place to insert the post than the mesiobuccal canal. However, if insertion into the mesiobuccal canal is unavoidable, there should be consideration on the occlusal contact, making central fossa and distal marginal ridge the main functioning areas.
Subject(s)
Dental Pulp Cavity , Dental Stress Analysis/methods , Finite Element Analysis , Imaging, Three-Dimensional/methods , Molar , Post and Core Technique , Bite Force , Elastic Modulus , Mandible , Models, Dental , Reference Values , Reproducibility of Results , Stress, Mechanical , Surface Properties , Weight-BearingABSTRACT
Abstract Objective The purpose of this study was to evaluate, by using finite element analysis, the influence of post location and occlusal loading location on the stress distribution pattern inside the root canals of the mandibular 1st molar. Material and Methods Three different 3-D models of the mandibular 1st molar were established: no post (NP) - a model of endodontic and prosthodontic treatments; mesiobuccal post (MP) - a model of endodontic and prosthodontic treatments with a post in the mesiobuccal canal; and distal post (DP) - a model of endodontic and prosthodontic treatments with a post in the distal canal. A vertical force of 300 N, perpendicular to the occlusal plane, was applied to one of five 1 mm2 areas on the occlusal surface; mesial marginal ridge, distal marginal ridge, mesiobuccal cusp, distobuccal cusp, and central fossa. Finite element analysis was used to calculate the equivalent von Mises stresses on each root canal. Results The DP model showed similar maximum stress values to the NP model, while the MP model showed markedly greater maximum stress values. The post procedure increased stress concentration inside the canals, although this was significantly affected by the site of the force. Conclusions In the mandibular 1st molar, the distal canal is the better place to insert the post than the mesiobuccal canal. However, if insertion into the mesiobuccal canal is unavoidable, there should be consideration on the occlusal contact, making central fossa and distal marginal ridge the main functioning areas.
Subject(s)
Post and Core Technique , Finite Element Analysis , Imaging, Three-Dimensional/methods , Dental Pulp Cavity , Dental Stress Analysis/methods , Molar , Reference Values , Stress, Mechanical , Surface Properties , Bite Force , Reproducibility of Results , Weight-Bearing , Models, Dental , Elastic Modulus , MandibleABSTRACT
A retrospective study for the combination of suture anchor and selective sesamoidectomy for treating volar instability of the metacarpophalangeal joint (MCPJ) of the thumb. Eleven patients with hyperextension of the MCPJ of the thumb underwent volar plate repair using a volar or voloradial approach. All the patients were reviewed radiologically and clinically using both objective and subjective criteria. The patients presented with sesamoid fractures (n = 2), sesamoid subluxation (n = 1), isolated volar plate laxity (n = 4), isolated sesamoid fracture (n = 4), and metacarpal condyle fracture (n = 2). The inner intersesamoid distance was 4.6 mm and the outer intersesamoid distance was 14.2 mm. The Disabilities of the Arm Shoulder and Hand and Michigan Hand Outcomes Questionnaire scores showed improvement. Volar plate repair using a suture anchor and selective sesamoidectomy is effective with regard to pain relief and stabilisation of volar instability of the thumb.
Subject(s)
Metacarpophalangeal Joint/injuries , Orthopedic Procedures/methods , Palmar Plate/injuries , Suture Anchors , Suture Techniques/instrumentation , Thumb/injuries , Adult , Equipment Design , Female , Follow-Up Studies , Humans , Male , Metacarpophalangeal Joint/diagnostic imaging , Metacarpophalangeal Joint/surgery , Middle Aged , Palmar Plate/diagnostic imaging , Palmar Plate/surgery , Retrospective Studies , Thumb/diagnostic imaging , Thumb/surgery , Tomography, X-Ray Computed , Treatment Outcome , Young AdultABSTRACT
A twenty-year-old male visited our clinic with wrist and long finger metacarpophalangeal (MP) joint pain. Dynamic ultrasonography revealed sagittal band (SB) ulnar subluxation and extensor carpi ulnaris (ECU) volar subluxation. Magnetic resonance imaging showed longitudinal splitting and dislocation of the volar half slip of the ECU tendon. The redundant radial SB was augmented and ECU sheath was advanced to the periosteum using suture anchors. He was able to perform his previous activities at the last follow-up. We encountered a case of "simulateous" ECU dislocation with extensor tendon subluxation of the long finger at the MP joint. Therefore, we report this case with a review of the relevant literature.
Subject(s)
Finger Injuries/diagnosis , Finger Injuries/surgery , Tendon Injuries/diagnosis , Tendon Injuries/surgery , Humans , Magnetic Resonance Imaging , Male , Ultrasonography , Young AdultABSTRACT
PURPOSE: This study investigated the influence of bone quality and surgical technique on the implant stability quotient (ISQ) value. In addition, the influence of interfacial bone quality, directly surrounding the implant fixture, on the resonance frequency of the structure was also evaluated by the finite element analysis. MATERIALS AND METHODS: Two different types of bone (type 1 and type 2) were extracted and trimmed from pig rib bone. In each type of bone, the same implants were installed in three different ways: (1) Compaction, (2) Self-tapping, and (3) Tapping. The ISQ value was measured and analyzed to evaluate the influence of bone quality and surgical technique on the implant primary stability. For finite element analysis, a three dimensional implant fixture-bone structure was designed and the fundamental resonance frequency of the structure was measured with three different density of interfacial bone surrounding the implant fixture. RESULTS: In each group, the ISQ values were higher in type 1 bone than those in type 2 bone. Among three different insertion methods, the Tapping group showed the lowest ISQ value in both type 1 and type 2 bones. In both bone types, the Compaction groups showed slightly higher mean ISQ values than the Self-tapping groups, but the differences were not statistically significant. Increased interfacial bone density raised the resonance frequency value in the finite element analysis. CONCLUSION: Both bone quality and surgical technique have influence on the implant primary stability, and resonance frequency has a positive relation with the density of implant fixture-surrounding bone.
