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OBJECTIVE@#To study the self-tapping performance test method of self-tapping bone screws based on the YY/T 1505 standard.@*METHODS@#With reference to the method of YY/T 1505, various factors affecting the self-tapping force test was optimised, and the self-tapping force judgment method was improved.@*RESULTS@#The experimental results showed that the self-tapping force obtained by the improved self-tapping force judgment method has good repeatability and high stability of the experimental data. At the same time, the test results of other influencing factors indicated that the manufacturer should fully consider the test material and the size of the pre-drilled hole.@*CONCLUSIONS@#An improved method for judging the self-tapping force is helpful for the repeatability and stability of the test data. This study has certain significance referring to the self-tapping performance test of self-tapping bone screws.
Assuntos
Fenômenos Biomecânicos , Parafusos ÓsseosRESUMO
Objective To test the validity for mechanical equation of the TC4 self-tapping bone screw and analyze the influence of bone screw parameters on its mechanical properties. Methods In order to derive the equation of self-tapping and pull-out for bone screw, the physical model of bone screw-polyurethane foam block was built. By reference of ASTMF543-07 standard specification and test method for metallic medical bone screw, the mechanical verification tests of selected conical head shallow thread locking bone screw (HAZ) and conical head deep thread locking bone screw (HBZ) with different diameters were performed on Instron E3000 mechanical testing machine, and the data of self-tapping force, self-tapping torque and pull-out force from 5 groups of bone screws were tested respectively. Results The calculated and measured values were basically the same, except for a few points with large individual errors. The average error of the two values was 11.02%, so the theoretical calculation formula was highly credible. The bone screw with a larger diameter or a higher tooth height would require greater self-tapping force and pull-out force. Conclusions The research results provide the calculation basis for mechanical properties of bone screw and the research direction for optimization and improvement of bone screw in future.
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Objective To assess theapplication values of self -tapping micro-screw implant anchorage in treatment of Angle's class II division 1 malocclusion with deep overburden jaws , compared with the traditional anchor-age.Micro-screw implantswere inserted in maxillary teeth of patients with Angle's class II division 1 malocclusion with deep overburden jaws tostrengthen anchorage .Changesin position of the maxillary incisor and the first molar were compared.Methods 68 cases of Angle's class II division 1 malocclusion with deep overburden jaws were selected and randomly divided into the research group and the control group .The research group wastreated with a self -tap-ping micro-screw implant as ananchorage .The control group was treated with Nance bow , transpalatal arch or in combination with face bow as strong anchorage .The total treatment time , line spacing and the angle differences be-tween the U1/SN of X-ray cephalometry before and after treatment were compared in two groups .Results ①The-self-tapping micro-screw implant kept stability without looseness .Thesoft tissue surrounding dental implants had no swellings or infections .Patients had no obvious discomfort .②The average periods of treatmentin the research group and the control group treatment were 20 months and 26 months, respectively.③The soft -tissue profilein the re-search group was improved significantly , with 4.26 mm and 4.54 mmof the adductions ofthe upper and lower lips rel-ative to aesthetic plane respectively .The angle of U1/SN was reduced 10.2°.Theadductionsof the upper and lower lipsin the control group relative to aesthetic plane were 2.88 mm and 3.01 mm respectively and there werestatistically significantdifferencesin two groups .There were no remarkableanteroposterior and verticalmovement after correction of maxillary first molars(p>0.05)but the anteroposterior incisor movement in the research group .The movements were statistically significant differences(p<0.01).Conclusion Compared with the traditional anchorage technique , mi-cro-screw implant anchorage can better control teeth movement and shorten the treatment time .
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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.