Dental Tribune United Kingdom Edition

February 14-20, 2011United Kingdom Edition the effects of minor misfit of the framework are not trans- ferred directly to the implants, as is the case with prosthe- sis-retaining screws. In addi- tion, the exposure of screw ac- cess holes in esthetic areas of the mouth can be avoided. On the other hand, any excess retained cement extruding from the prosthesis/abutment interface, especially when lo- cated sub-gingivally, can cause inflammation, infection, and periodontal complications. As more and more den- tal practitioners are focusing on implant-supported fixed partial dentures (FPD) restor- ing dentists need to understand the restorative options they may have to deal with. Many dental practitioners and labs will persistently use a screw-re- tained implant-supported fixed partial denture, and thereby promote the utmost choices of serviceability, cosmetic result and maintenance of optimised bite possible. At the same time, in recent years the utilisation of adjunc- tive state of the art Cone Beam CT and technologies and 3-D derived virtual planning soft- ware solutions altered the man- ner in which we pull together di- agnostic data, plan and execute bothsimpleandcompleximplant cases. As a result, more and more implant trajectories are consist- ent with the planned prosthetic trajectories. Yet, some cases are still driven by the residual bone trajectories and are left to the re- storing dentists’ decision as far as the final restorative option. In other words, when the implant trajectories are inconsistent with the planned prosthetic tra- jectories, the screw-retained implant-supported fixed par- tial denture systems offer an opportunity to minimise any controversy between the sur- geons, restorative dentists and labortories, creating greater un- derstanding, appreciation and professional camaraderie. Case Report Patient presented for implant supported FPD after having teeth #8, 9, 10 extracted with socket preservation. A CBCT study was per- formed with the iCAT CBCT machine (Imaging Sciences International, Hatfield, Pa) and revealed reasonable al- veolar dimensions, both vertical and horizontal. However, by utilising Implant- Master™software(iDentImaging, Inc., Foster City, CA, 94404- 1294), it was discovered that the residual bone trajectory (RBT) and the planned pros- thetic trajectory (PPT) were in conflict, that is, projecting a compromised restorative tra- jectory lingually in implant site #9 and buccally in implant site #11 (Fig 1). Nevertheless, fol- lowing a treatment planning conference, rather than con- sidering bone grafting, a deci- sion was made to proceed with these angulations and a 3-D reconstruction of a patient’s anatomy was attained and a virtual surgical guidance template was designed and computer manufactured with precise drilling holes’ distribu- tion and trajectory for implants #9 and 11. The palatal trajectory of the implant in tooth position #9, the patient’s deep bite which re- sulted in severely limited space for prosthetic components, dic- tated a screw-retained prosthet- ic FPD construction solution for the case. The extremely buccal an- gulation of the implant re- placing tooth #11 resulted in a buccaly located screw access opening, which compromised aesthetics, and potentially weakened the porcelain around the screw opening in the pro- posed screw-retained three units FPD. The aesthetic di- lemma could be solved by either gold plating of the metal portion of the screw chamber, which can reduce the need for opaque composite material, or by metal cut back to hide the non- aesthetic metal. We chose to overcome this aesthetic and structural obstacle by using a separate telescoic crown design to cover the metal sub- ‘As more dental practitioners are focusing on implant-supported fixed partial dentures restoring dentists need to under- stand the restorative options they may have to deal with’ Figures 1a & 1b: Figure 1: CBCT study was performed with the iCAT CBCT machine (Imaging Sciences International, Hatfield, Pa). By utilis- ing ImplantMaster ™ software (iDent Imaging, Inc., Foster City, CA, it was noted in the 3DVR (a) and Virtual surgical template (b) that the resid- ual bone trajectory and the planned prosthetic trajectory were in conflict, projecting compromised restorative trajectory lingually in implant site #9 and buccally in implant site #11. page 13DTß