23 October 2022

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A critical review of implant placement in wrong sites

By Claudia Dellavia et al.

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Introduction: The key factors that could positively influence the maintenance of osseointegration over time include the surgical technique, the recipient bed, the design of the implant, the surface characteristics of the implant, biocompatibility of materials and loading conditions. However, although the key role of these factors is known since many years, there has been some progress in the field of surgical techniques, materials and biomechanical concepts in the latest decades. Thus, the aim of this paper was to focus on the main anatomical and clinical factors (sites with low bone density, limited bone mass or biomechanically unfavorable cases) that can affect the load that develops at the bone/implant surface during chewing activity in cases where bone augmentation procedures are not performed.

Materials and methods: A critical review of articles that investigated osseointegration and survival rate of dental implants placed in anatomical and biomechanical adverse conditions was performed. The articles have been identified through an electronic database (PubMed). Two experienced and independent operators selected articles published in English between 1980 and 2017. Clinical and pre-clinical studies randomized and controlled clinical trials and systematic reviews were included and analyzed by the authors.

Results: Low bone density, limited amount of bone and biomechanically unfavorable cases are detrimental factors for long–term success of implant rehabilitation. Several implant-prosthetic related factors affect the stress distribution at the bone-implant interface.

Conclusions: Overload may cause implant-prosthetic rehabilitation failure and therefore some precautions should be taken during the treatment planning. In rehabilitation at low bone density sites, the highest primary stability should be addressed. In the presence of reduced width or height of the alveolar bone and when small or short diameter implants are placed, it is recommended to take measures to reduce the risk of fracture of the implant, including oblique or cantilever load limitation. In the case of biomechanically unfavorable situations (adverse functional habits and total fixed prostheses), it is important to reduce the stress at the level of the bone-implant interface, to prevent the risk of system fracture and to limit the distal cantilever. It is crucial to control the chewing function and patients’ habits after prosthetic rehabilitation.

Clinical significance: Low bone density, limited amount of bone and biomechanically unfavorable cases are detrimental factors for long-term success of implant rehabilitation. Overload may cause implant-prosthetic rehabilitation failure and therefore some precautions should be taken during the treatment planning. In sites with adverse anatomical and biomechanical conditions it is important to reduce stress at bone-implant interface and it is crucial to control the chewing function and patients’ habits after prosthetic rehabilitation.

By Gaia Pellegrini, Marilisa Torna, Luca Francetti, Nicolò Cavalli, Daniela Carmagnola and Claudia Dellavia. This article originally appeared in Dental Cadmos.