Effect of access cavities on the biomechanics of mandibular molars: a finite element analysis.

INTRODUCTION: This study aimed to predict the fracture resistance of a mandibular first molar (MFM) with diverse endodontic cavities using finite element analysis (FEA). METHODS: Five experimental finite element models representing a natural tooth (NT) and 4 endodontically treated MFMs were generated. Treated MFM models were with a traditional endodontic cavity (TEC) and minimally invasive endodontic (MIE) cavities, including guided endodontic cavity (GEC), contracted endodontic cavity (CEC) and truss endodontic cavity (TREC). Three loads were applied, simulating a maximum bite force of 600 N (N) vertically and a normal masticatory force of 225 N vertically and laterally. The distributions of von Mises (VM) stress and maximum VM stress were calculated. RESULTS: The maximum VM stresses of the NT model were the lowest under normal masticatory forces. In endodontically treated models, the distribution of VM stress in GEC model was the most similar to NT model. The maximum VM stresses of the GEC and CEC models under different forces were lower than those of TREC and TEC models. Under vertical loads, the maximum VM stresses of the TREC model were the highest, while under the lateral load, the maximum VM stress of the TEC model was the highest. CONCLUSION: The stress distribution of tooth with GEC was most like NT. Compared with TECs, GECs and CECs may better maintain fracture resistance, TRECs, however, may have a limited effect on maintenance of the tooth resistance.

Endodontic management of a fused left maxillary second molar and two paramolars using cone beam computed tomography: A case report.

BACKGROUND: Fused teeth usually involve several complications, such as the development of caries in the groove between fused crowns, tooth impaction, diastemas, aesthetic and periodontal problems, and pulpal pathosis, due to the complex anatomical structure of fused teeth. A thorough diagnosis is paramount to forming an accurate treatment plan and obtaining a favourable prognosis. With the advent of cone-beam computed tomography (CBCT), accurate 3-dimensional images of teeth and their surrounding dentoalveolar structures can now be readily obtained, and the technology can accurately provide a minimally invasive approach to acquire detailed diagnostic information. Therefore, we utilize CBCT data herein to generate a digital model for the infected region in a patient, and this model enables us to better plan the management of his case. CASE SUMMARY: This report details the diagnosis and endodontic treatment of a rare case involving a fused maxillary second molar and two paramolars with apical periodontitis. The patient experienced pain upon biting and cold sensitivity in the area of the maxillary left molar. No caries or other defects were identified in these teeth, and a normal response to a pulp electric viability test was observed. With the aid of CBCT and digital model technology, we initially suspected that the infection originated from the isthmus between the maxillary second molar and two paramolars. Therefore, we only treated the isthmus by an endodontic approach and did not destroy the original tooth structure; furthermore, the vital pulp was retained, and good treatment outcomes were observed at the 24-month follow-up. CONCLUSION: This finding may provide new insights and perspectives on the diagnosis and treatment of fused teeth.

[Adenovirus mediated expression of recombinant human single chain interleukin-27(rhscIL-27) fusion gene in hepatoma cells].

AIM: To explore the adenovirus mediated expression of recombinant human single chain interleukin-27(rhscIL-27) fusion gene in hepatoma cells. METHODS: The rhscIL-27 fusion gene was subcloned into the shuttle plasmid pAdTrack-CMV and then clone the homologous recombinant adenovirus genomic plasmid pAdEasy in bacteria. The identified recombinant plasmid AdIL-27 was tranfected into 293 cells, and then the adenovirus did the package and amplification. The HepG2 cells were infected with AdIL-27 and the target gene expression was determined by RT-PCR and ELISA. The biological activity of rhscIL-27 was detected by IFN-gamma inducing assay. RESULTS: Restriction endonuclease and gene sequencing confirmed that the recombinant adenovirus vector of rhscIL-27 fusion gene was successfully constructed. The expression of rhscIL-27 fusion gene was observed at 48 h after the transfection of the HepG2 cells with AdIL-27. The IFN-gamma inducing assay showed that the rhscIL-27 protein has the ability inducing IFN-gamma secretion. CONCLUSION: By using adenovirus expression system, rhscIL-27 fusion gene with biological activity is expressed successfully in hepatoma cells. This experiment laid a foundation for gene therapy of hepatoma with IL-27.

[The application of radiological imaging in the forensic pathology about cervical part].

Multislice spiral computed tomography (MSCT) and magnetic resonance imaging (MRI) are useful to analyze cervical injury. Especially in injury of skeleton and soft tissue, it has equal value with conventional autopsy. Even they can reparation some shortcoming consisted in the cervical part autopsy. In some difficult postmortem examination of decomposed, charred or highly infectious cadavers and in some religion country, they should be a useful alternative way to examine injury in cervical part of cadaver such as mechanical asphyxia, whiplash injury, vertebra injury, or vascular injury.

[Effect of calpain inhibitor I on ikappaBalpha expression and cytokine secretion in RAW264.7 cells attacked with LPS].

AIM: To explore the effect of calpain inhibitor I(CI-I) on ikappaBalpha expression and cytokine secretion in RAW264.7 cells after LPS attack. METHODS: RAW264.7 cells were pretreated with CI-I for 1 h and attacked with LPS. The ikappaBalpha expression and TNF-alpha and IL-6 secretion were detected by Western blot and ELISA, respectively. RESULTS: CI-I inhibited the decrease of ikappaBalpha expression in RAW264.7 cells treated with LPS. The secretion of both TNF-alpha and IL-6 secretion was notably increased after RAW264.7 cells were treated with LPS for 4 h or 8 h. CI-I and dexamethasone(DEX) inhibited these effects, and the combination of DEX and CI-I had synergistic effect. CONCLUSION: CI-I and DEX can inhibit the decrease of ikappaBalpha expression and prevent TNF-alpha and IL-6 secretion in RAW264.7 cells attacked with LPS, which contributes to the alleviation of cellular injury.