CAD/CAM international magazine of digital dentistry

I research _ SFI-Bar required for cutting in the laboratory. The cutting of the tube bar must always be carried out extra-orally. Once the tube bar has been cut, the ball joints are insertedintoeachendofthetubebarpriortoseating ontheimplantadapters(Figs.7a–d)andtorquedinto place. The SFI-Bar is now complete and the patient is ready for the retentive element to be housed in the denture. The ball joints can accommodate non-par- allel implant placement up to a maximum of 15° angulationcorrection.Theabsenceofanysolderedor welded joints means that a greater length of the bar canbeengagedbytheretentiveclip.Inconventional techniques, the presence of a weld increases the bar thickness, at that point preventing any retentive clip engaging that area. In the SFI-Bar, the clip engages the full length of the bar between the ball joints (Fig. 8). The bar assembly must be parallel with the occlusalplane;therefore,aselectionofimplantadap- ters of varying lengths should be available. Most of the major implant companies offer CAD/ CAM-fabricated bar and clip solutions. However, thesebarsarerelativelyexpen- siveandarefabricatedthrough a conventional impression and master cast technique. Studies have shown that 50per cent of all errors during impression making and cast fabrication resultinnon-passivefitofbars and frameworks. Thus, any bar fabricated through an impres- sion or cast technique cannot be truly passive.6–8 A clinical case will be presented below in order to demonstrate the direct chair-side method and the use of the SFI-Bar on two implants to restore an edentu- lous mandible. In addition, the mainpointsforusewiththein- direct method will be outlined. _Case presentation In 2006, a 60-year-old female patient initially presented, complaining of an ill-fitting lower den- ture. The patient had worn a conventional complete mandibular denture for over 20 years, opposing a metal-based maxillary removable partial denture. The patient had visited a denturist on several occa- sions to try to improve the situation. After multiple relining procedures, the patient decided to seek ex- pert help. An OPG radiograph revealed a severely resorbedmandiblethatclinicallypresentedasaclas- sicbowl-shapeddeficiency(Figs.9a–c).Radiographic examination revealed there was adequate bone volume in the anterior region for the placement of dental implants. However, a fixed solution would only have provided a shortened dental arch, as the mental foramen had become more mesial owing to bone resorption. Placing implants distal to the men- talforamenwasnotanoption,owingtotheproxim- ityoftheinferiordentalnerveandlackofboneheight. The patient was not keen to have any nerve reposi- tioningorcomplexbonegrafting.Anotherimportant factor negating the fixed solution was the size of the volume defect. This would have been difficult both tocorrectandtomaintainandwouldhaveproduced apooraestheticresult.Theadditionalbulkofdenture flanges allowed proper facial support. Afterdiscussingalltherelevantissues,thepatient decided that the removable overdenture retained withtwoimplantswasthebestandleastcomplicated treatment option for her. The upper denture was not anissueforthepatient,asitwasretentiveandstable. In order to limit costs, the upper denture was not replaced. A surgical guide was fabricated after the vertical dimension, aesthetic and phonetic parame- 16 I CAD/CAM 3_2012 Fig. 7a Fig. 7b Fig. 7c Fig. 7d Fig. 8