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METHODSA 3D numerical model of the all-ceramic crown of the right mandibular first molar was generated from scanned CT images. Finite element analysis (FEA) was used to evaluate the stress distribution in the all-ceramic crown when it was subjected to 5 load conditions.

RESULTSStress distributions under 5 loading conditions were obtained. Stress concentrations were generally found near the loading areas at the veneer and at the lower surface of the core beneath the loading areas. In the 5 loading conditions, it was found that when the crown was loaded with vertical concentrated load, the tensile stresses around the shoulder areas were uniform, while stress concentration with maximum of 32.25 MPa was found at the shoulder areas in lingual-buccal direction when loads were applied at an angle of 10 degrees with the tooth axis on the buccal side. The masticatory load which was applied at 20 degrees with the tooth axis on the buccal side would cause stress concentration at the shoulder in mesial-distal direction. The maximum value could reach 11.29 MPa.

CONCLUSIONSThe occlusal surface of the all-ceramic crown must be trimmed to increase multiple contact zones with the opposite surfaces in antagonist teeth to avoid excessive concentrated stress that may cause crown failure.

Crowns ; Dental Porcelain ; Dental Stress Analysis ; methods ; Finite Element Analysis ; Materials Testing

7.Historical evolution and development countermeasures of uncommon-territorial herbs.

Hua-sheng PENG ; De-qun WANG ; Jin-da HAO ; Jin XIE ; He-ling LIU ; Dai-yin PENG ; Lu-qi HUANG

China Journal of Chinese Materia Medica 2015;40(9):1635-1638

8.Small needle-knife for the treatment of tennis elbow according to its classification.

Yin-Sheng ZHU ; Xin-Miao YAO ; Yi LU

China Journal of Orthopaedics and Traumatology 2013;26(8):659-662

OBJECTIVETo observe clinical effect of different treatments for tennis elbow with small needle-knife according to its classification.

METHODSFrom March 2011 to December 2012,100 patients with 123 tennis elbows were treated with small needle-knife, including 36 males and 64 females, ranging in age from 29 to 76 years old (averaged, 49 years old). The course of disease ranged from 3 months to 2 years (averaged, 7.2 months). According to the classification, 46 elbows were with extra-articular type, 34 elbows with intra-articular type, 20 elbows with mixed type. All the patients were treated with small needle-knife by using different methods according to its classification.

RESULTSAll patients were followed up for 6 to 12 months with an average of 8.2 months. After treatment, the symptoms and signs of the patients improved significantly (P < 0.01). According to the criteria of the Verhaar scoring system, 35 of 46 patients with extra-articular type got an excellent result, 9 good, 2 fair; 24 of 34 patients with intra-articular type got an excellent result, 9 good, 1 fair; 9 of 20 patients with mixed type got an excellent result, 8 good, 3 fair.

CONCLUSIONThe causes of tennis elbow can not be explained by single pathogenesy, the patients with tennis elbow should be treated with different methods according to its classification, and the therapeutic effects can be improved.