CAD/CAM - international magazine of digital dentistry

I research _ single molar restoration Fig. 1_Load distribution during mastication shows marked increase in the molar and premolar area.23 Fig. 2_Occlusal view showing a missing first molar. The mesio-distal width is very wide and restoration couldn’t compensate it leaving a space distally. Fig. 3_Proximal cantilever shown radiographic view of maxillary right first molar on standard Brånemark implant with standard abutment (Nobel Biocare).1 _Thesingle-toothrestorationhasbecomeoneof themostwidelyusedproceduresinimplantdentistry.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 para- functional habits, can easily compromise the stability oftherestorations(Fig.1).2,3 The single-molar implant-supported restoration hashistoricallypresentedachallengeintermsofform and function. The mesiodistal dimensions of a molar exceedthatofmoststandardimplants(3.75to4.0mm), creating the possibility of functional overload result- ing 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 11.0 mm) with a crestal width greater than or equal to 8 mm (Fig. 4 a).5 Clinical parameters govern- ing the proposed restoration should be carefully as- sessedinlightoftheavailabilityofimplantsandcom- 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 recent 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 implantrestorations(Figs.4b&c). Moststandardimplantsandtheirassociatedpros- thetic components, when used to support a double implant molar restoration, will not fit in the space oc- cupied by a molar unless the space has been enlarged (12mmorlarger).4 Moscovitchsuggeststhatthecon- cept of using 2 implants requires the availability of a strongandstableimplanthavingaminimumdiameter of3.5mm.Additionally,theassociatedprostheticcom- ponentsshouldideallynotexceedthisdimension.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 cal- culationofstressesanddeformationsofeachelement 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 ap- propriate material properties that correspond to the properties of the structure to be modeled. Boundary conditions are applied to the model to stimulate in- teractions with the environment.14 This model allows simulated force application to specific points in the system, and it provides the resultant forces in the surrounding structures. FEA is particularly useful in the evaluation of dental prostheses supported by implants.13-16 TwomodelsweresubjectedtoFEAstudy tocomparebetweenawideimplantrestorationversus thetwoimplantrestorationoflowerfirstmolar. Single molar restoration —Wide implant versus two conventional Authors_Prof. Amr Abdel Azim, Dr Amani M. Zaki & Dr Mohamed I. El-Anwar, Egypt 22 I CAD/CAM 1_2013 Fig. 2 Fig. 3Fig. 1