Biomechanical Factors at Bone-implant Interface- an Animal Model Pilot Study PDF Download

Author: Markel Dieguez-Pereira
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Languages : en
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BackgroundImplant-supported rehabilitations have become popular in last years because their high survival and success rates. Also, loading protocols have been shortened due to the development of the implant surfaces.During the provisionalitation of the implants the use of restoration with a high elastic material has been recommended to decrease the load transfer to the surrounding bone, because a load excess over the bone elastic limit could cause the implant loss due to overload. On the other hand, other in vitro studies recommended the use of higher Young u0301s modulus materials because they absorb the most part of the energy transferring less stress to the bone-implant interface.Also, splinting the implants designing splinted prosthetic structures guarantees that the maximum stress transferred to any of the implants will be lower than the load applied.This load control of implant-supported restorations is important because an excess of the stress transferred to the bone-implant interface could induce a micro motion >150u03bcm and the lost of the osseointegration.Hypothesis-Elastic materials in implant-supported restorations transfer less tension to the bone-implant interface.-Implant-supported splinted restorations transfer less tension to the bone-implant interface.-The lack of apex cortical causes more stress transmission to the bone-implant interface and higher micromotion of the implant.Materials and MethodsSix 3.5x8 Vega Klockner implants were inserted in both tibia of a New Zealand rabbit and RFA analysis was performed at this time by Penguin RFA device . An impression was carried out splinting the 3 implants with the transfer abutments to elaborate 2 identical single restorations, one of monolithic zirconia and another one of PMMA and 8 implant-supported bridges, 4 of each material with the same design. After 6 weeks of osseointegration, the animal was sacrificed and a new RFA analysis was carried out. Then, one strain gauge was stuck on the u201cbuccalu201d bone crest around each implant. Later, cement-screwed restorations were screwed at 30N to the implants and after this, a static and dynamic load of 100N was applied over the central fossa in the single restoration cases and over 3 different points when the bridges where screwed (firstly over the central fossa of one of the premolars, then over the other one and finally over the connector). Once the test was completed, all strain data were recorded. Finally, the apical cortical bone was removed and the load test was repeated in the same way.ResultsISQ mean value using multipage abutment was 62,8 (SD 10,35) in the moment of the surgery and 6 weeks after was 84,67 (SD 13,26) in the implants with the apical cortical bone (Group A) and 74.5 (SD 9,23) in the bone without apical cortical bone (Group B). Micro-strain mean value in single crowns was 103,08 u03bcstrains (SD 61,96) in group A and 471,94 u03bcstrains (SD 202,74) in group B. Micro-strain mean value in single crowns was 103,08 u03bcstrains (SD 61,96) in group A and 471,93 u03bcstrains (SD 202,74) in group B. In group A splinted crowns microstrain mean value was 57,03 u03bcstrains and in group B 202,1 u03bcstrains.Conclusions and Clinical Implications-When there is a lack of apical cortical bone ISQ values decrease. -Bone microstrains are higher when single crowns are placed and when there is an absence the apical cortical bone. -Bone microstrains are lower when the crowns are splinted and when there is a lack of the apical cortical this effect is more evident.-There is a tendency that the higher ISQ values the lower microstrain occurs at crestal level in all the cases. -When a dynamic load is applied bone microstrains are higher. -In most cases, monolithic zirconia causes higher bone microstrain.