Numerical results suggest that implant diameter may be more effective than implant length as a design parameter to control the risk of bone overload. For a given implant in the molar region, the worst load transmission mechanisms arise with maxillary placement, and implant biomechanical behavior greatly improves if bone is efficiently preserved at the crest. Statement of problem.Load transfer mechanisms and possible failure of osseointegrated implants are affected by implant shape, geometrical and mechanical properties of the site of placement, as well as crestal bone resorption. Suitable estimation of such effects allows for correct design of implant features.Purpose. The purpose of this study was to analyze the influence of implant diameter and length on stress distribution and to analyze overload risk of clinically evidenced crestal bone loss at the implant neck in mandibular and maxillary molar periimplant regions. Material and methods.Stress-based performances of 5 commercially available implants (2 ITI, 2 Nobel Biocare, and 1 Ankylos implant; diameters of 3.3 mm to 4.5 mm, bone-implant interface lengths of 7.5 mm to 12 mm) were analyzed by linearly elastic 3-dimensional finite element simulations, under a static load (lateral component: 100 N; vertical intrusive component: 250 N). Numerical models of maxillary and mandibular molar bone segments were generated from computed tomography images, and local stress measures were introduced to allow for the assessment of bone overload risk. Different crestal bone geometries were also modelled. Type II bone quality was approximated, and complete osseous integration was assumed.Results. Maximum stress areas were numerically located at the implant neck, and possible overloading could occur in compression in compact bone (due to lateral components of the occlusal load) and in tension at the interface between cortical and trabecular bone (due to vertical intrusive loading components). Stress values and concentration areas decreased for cortical bone when implant diameter increased, whereas more effective stress distributions for cancellous bone were experienced with increasing implant length. For implants with comparable diameter and length, compressive stress values at cortical bone were reduced when low crestal bone loss was considered. Finally, dissimilar stress-based performances were exhibited for mandibular and maxillary placements, resulting in higher compressive stress in maxillary situations.Conclusions. Implant designs, crestal bone geometry, and site of placement affect load transmission mechanisms. Due to the low crestal bone resorption documented by clinical evidence, the Ankylos implant based on the platform switching concept and subcrestal positioning demonstrated better stress-based performance and lower risk of bone overload than the other implant systems evaluated. (J Prosthet Dent 2008;100:422-431) The influence of implant diameter and length on stress distribution of osseointegrated implants related to crestal bone geometry: A threedimensional fi...

209nomas (OPSCCs) (3, 4). The etiologic role of human papillomavirus infection in the development of Squamous Cell Carcinomas (SCC) of the uterine cervix has been widely demonstrated, so that this tumour is caused, in almost of the cases, by the persistent infectious status by high-risk atypical genotypes. There is also strong evidence to support a causal role of these viruses in the etiopathogenesis of SCC, both in the anogenital area and in the head area (for example, pharynx, larynx and oral cavity) (5). Genital HPV infection is one of SUMMARY Purpose. The aim of this paper is to describe epidemiology and clinical manifestations of oral infection by Human papillomavirus (HPV), with particular attention to potential malignant lesions. Materials and methods. A systematic review of the literature was conducted to describe the state of the art about HPV infection in oropharyngeal mucosa and its modalities of transmission, with particular attention to possible simultaneous infection in multiple anatomic sites. The aspects of prevention and control of infection by administering vaccines and the diffusion of sexual education campaigns are discussed also. Therapeutic protocols are also described where necessary. Results. In recent years there has been a growing interest in HPV oral medicine, suggesting a role of such a family of viruses in the development of neoplasms of the oropharyngeal district as well as of the uterine cervix. Even if the mass media have increasingly faced the problem, causing frequent alarming among patients, the dentist therefore needs a complete and up-to-date knowledge of this infectious condition that is one of the most common causes of sexually transmitted mucous membrane infections (e.g. genital, anal and oral). Conclusions. Recent studies about HPV infection are a basic requirement in order to promote the health of patients and provide them with the most exhaustive indications from dentists.

IAI geometry influences both bacterial and yeast colonization inside the implants as well as the torque value used to connect abutments to implants.

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