Keywords: platform switching, dental implants, finite element.

Histologic and radiographic observations suggest that a biological dimension of hard and soft tissues around dental implants extends apically from the implant-abutment interface [1]. The stress and strain distribution developed on this surrounding bone is the main mechanical reason for the failure of many implants. Thus, the establishment and maintenance of osseointegration requires implant stability [2,3] and, therefore clinical measurements of implant stability and osseointegration are the input to assess the clinical success.

The purpose of this study is to analyze and compare the implant-bone interface stresses using three-dimensional finite element models of a partially osseointegrated implant with platform and a conventional matching-diameter implant platform and abutment in the anterior mandible. In order to reach this purpose the mechanical properties of both peri-implantar regions are modelled as isotropic and resonance frequency analysis is used to validate their values. Material properties of compact and cancellous bone are modelled as transversely isotropic and isotropic, respectively. The osseointegration process is simulated by changing the Young's modulus of the implant-bone interfacial tissue. The numerical resonance frequency is validated by means of clinical measurements assessed by a resonance frequency analysis (RFA) device that uses magnetic technology (an Ostell Mentor device). The results suggest that the use of resonance frequency analysis using an electromagnetic pulse is sensitive and hence can be used to qualify the implant stability during the osseointegration process.

For static analysis one model is simulated using a 4.3 mm diameter abutment connection and the other uses a narrower 3.7 mm diameter abutment connection, simulating a platform-switching configuration. The loading scenario consists of an oblique (200 N vertical and 40 N horizontal) occlusal load and, perfect bonding is assumed at all interfaces. From the results presented on the paper it is clear that the platform switching technique enables the reduction of the stress concentration on the peri-implantar cortical region and, it seems that the stress distribution area does not change significantly between models.

1

R.J. Lazzara, S.S. Porter, "Platform switching: a new concept in implant dentistry for controlling postrestorative crestal bone levels", Int J Periodontics Restorative Dent., 26, 9-17, 2006.

2

A.B. López, J.B. Martínez, J.L. Pelayo, C.C. García, M.P. Diago, "Resonance frequency analysis of dental implant stability during the healing period", Med Oral Patol Oral Cir Bucal, 13, 244-247, 2008.

3

P.O. Ostman, M. Hellman, I. Wendelhag, L. Sennerby, "Resonance frequency analysis measurements of implants at placement surgery", Int J Prosthodont, 19, 77-83, 2006.

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