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ePaper created 2015-05-22, 12:38:27 | version 1.38.0
Implant Tribune pages 15-17 Prof Marincola et al discuss short implants Short™ Implants Implant Tribune pages 18-20 Dr Pelegrine discusses the benefits of stem call therapy Stem cells in implant dentistry Implant Tribune page 12DTà Single molar restoration —Wide implant versus two conventional Prof Amr Abdel Azim, Dr Amani M Zaki & Dr Mohamed I El-Anwar T he single-tooth restora- tion has become one of the most widely used pro- cedures in implant dentistry.1 In the posterior region of the oral cavity, bone volume and density are often compromised. Occlusal forces are greater in this region and, with or without parafunc- tional habits, can easily compro- mise the stability of the restora- tions (Fig. 1). 2, 3 The single-molar implant- supported restoration has his- torically presented a challenge in terms of form and function. The mesiodistal dimensions of a mo- lar exceed that of most standard implants (3.75 to 4.0 mm), creat- ing the possibility of functional overload resulting in the failure of the retaining components or the failure of the implant (Figs. 2 & 3).4 Wider-diameter implants have a genuine use in smaller molar spaces (8.0 to 11.0mm) with a crestal width greater than or equal to 8mm (Fig. 4 a).5 Clini- cal parameters governing the proposed restoration should be carefully assessed in light of the availability of implants and com- ponents that provide a myriad of options in diameter, platform configurations and prosthetic connections. Many of the newer systems for these restorations are showing promising results in re- cent clinical trials.6-8 It has further been suggested by Davarpanah and others,9 Balshi and others,2 English and others10 and Bahat and Handelsman11 that the use of multiple implants may be the ideal solution for single-molar implant restorations (Figs. 4 b & c). Most standard implants and their associated prosthetic com- ponents, when used to support a double implant molar restora- tion, will not fit in the space occu- pied by a molar unless the space has been enlarged (12mm or larger).4 Moscovitch suggests that the concept of using 2 implants requires the availability of a strong and stable implant having a minimum diameter of 3.5 mm. Additionally, the associated pros- thetic components should ideally not exceed this dimension.2 Finite element analysis (FEA) is an engineering method that allows investigators to assess stresses and strains within a solid body.10-13 FEA provides calcu- lation of stresses and deforma- tions of each element alone and the net of all elements. A finite element model is constructed by breaking a solid object into a number of discrete elements that are connected at common nodal points. Each element is assigned appropriate material properties that correspond to the proper- ties of the structure to be mod- elled. Boundary conditions are applied to the model to stimulate interactions with the environ- ment.14 This model allows simu- lated force application to specific points in the system, and it pro- vides the resultant forces in the surrounding structures. FEA is particularly useful in the evalu- ation of dental prostheses sup- ported by implants.13-16 Two mod- els were subjected to FEA study Fig 1 Fig 2 Fig 3 Fig 4a Fig 4b Fig 4c