Evaluation of stress induced in peri-implant bone tissue by misfit in multi-implant prosthesis.

OBJECTIVES The objective of the present work was to use numerical analysis to evaluate the relevance of stress states induced in peri-implant bone tissue by a misfit in a dental fixed prosthesis. Misfits in both mesial-distal and lingual-labial directions were considered to investigate a realistic configuration of the problem. MATERIALS AND METHODS A finite element model of a portion of a mandible with two implants connected by a gold alloy bar was defined on the basis of the morphometric data of a partial edentulous patient. A specific procedure was developed to represent the bar-implant coupling in the case of a misalignment between the implant and central axes of the anchoring site to the bar. Loading conditions related to occlusal forces were also considered. RESULTS The numerical analysis of the implant-bridge misfit showed significant stress effects on the peri-implant bone tissue. For the specific prosthetic configuration considered, the maximum compressive stress was in the range of 40-60 MPa, depending on the misfit considered. The stress level was largely affected by the axial and bending stiffness characteristics of bar-implant compound. SIGNIFICANCE Stress analysis using numerical methods made it possible to estimate stress states with high accuracy in terms of intensity and location. For the case considered, stress induced by misfit was comparable with that related to occlusal forces. Therefore, a possible bar-implant misfit should be carefully considered to ensure the reliability of the prosthetic system.

[1]  Marco Ghisolfi,et al.  Long-term survival and success of oral implants in the treatment of full and partial arches: a 7-year prospective study with the ITI dental implant system. , 2004, The International journal of oral & maxillofacial implants.

[2]  M. Çehreli,et al.  The Significance Of Passive Framework Fit In Implant Prosthodontics: Current Status , 2001, Implant dentistry.

[3]  S A Aquilino,et al.  Strategies to achieve fit in implant prosthodontics: a review of the literature. , 1999, The International journal of prosthodontics.

[4]  R. T. Hart,et al.  Mechanics of bone tissue , 2003 .

[5]  Steven E Eckert,et al.  Cyclic loading of implant-supported prostheses: changes in component fit over time. , 2003, The Journal of prosthetic dentistry.

[6]  P. Branemark.  Osseointegration and its experimental background. , 1983, The Journal of prosthetic dentistry.

[7]  A Natali,et al.  Computer tomography for virtual models in dental imaging , 2003 .

[8]  B Rangert,et al.  Forces and moments on Branemark implants. , 1989, The International journal of oral & maxillofacial implants.

[9]  C Runte,et al.  Evaluation of accuracy of insertion of dental implants and prosthetic treatment by computer-aided navigation in minipigs. , 2003, The British journal of oral & maxillofacial surgery.

[10]  A. Sertgöz,et al.  Finite element analysis of the effect of cantilever and implant length on stress distribution in an implant-supported fixed prosthesis. , 1996, The Journal of prosthetic dentistry.

[11]  Shuichi Nomura,et al.  Biomechanical aspects of marginal bone resorption around osseointegrated implants: considerations based on a three-dimensional finite element analysis. , 2004, Clinical oral implants research.

[12]  A B Carr,et al.  The response of bone in primates around unloaded dental implants supporting prostheses with different levels of fit. , 1996, The Journal of prosthetic dentistry.

[13]  R Puers,et al.  Magnitude and distribution of occlusal forces on oral implants supporting fixed prostheses: an in vivo study. , 2000, Clinical oral implants research.

[14]  R DeLong,et al.  Elasticity of alveolar bone near dental implant-bone interfaces after one month's healing. , 2003, Journal of biomechanics.

[15]  K R Williams,et al.  Design of prosthetic cantilever bridgework supported by osseointegrated implants using the finite element method. , 1998, Dental materials : official publication of the Academy of Dental Materials.

[16]  Weinberg La,et al.  The biomechanics of force distribution in implant-supported prostheses. , 1993 .

[17]  S. Cowin.  Bone mechanics handbook , 2001 .

[18]  T. Dérand,et al.  Description and evaluation of a simplified method to achieve passive fit between cast titanium frameworks and implants. , 1998, The International journal of oral & maxillofacial implants.

[19]  P J Becker,et al.  Survival of fixed implant-supported prostheses related to cantilever lengths. , 1994, The Journal of prosthetic dentistry.

[20]  Monica Soncini,et al.  Experimental procedure for the evaluation of the mechanical properties of the bone surrounding dental implants. , 2002, Biomaterials.

[21]  R Pietrabissa,et al.  Experimental and computational approach for the evaluation of the biomechanical effects of dental bridge misfit. , 2000, Journal of biomechanics.

[22]  R. Pietrabissa,et al.  Testing the reliability of dental implant devices , 2003 .

[23]  Piero G. Pavan,et al.  Numerical approach to dental biomechanics , 2003 .

[24]  S. Longoni,et al.  A simplified method to reduce prosthetic misfit for a screw-retained, implant-supported complete denture using a luting technique and laser welding. , 2004, The Journal of prosthetic dentistry.

[25]  G C Michaels,et al.  Effect of prosthetic superstructure accuracy on the osteointegrated implant bone interface. , 1997, Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics.

[26]  M. Chiapasco,et al.  Implant-supported fixed cantilever prostheses in partially edentulous arches. A seven-year prospective study. , 2003, Clinical oral implants research.