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34 RESTORATIVE Dental Tribune Middle East & Africa Edition | 3/2017 Advanced Restorative Techniques And The Full Mouth Reconstruction - Full arch bridge design on implants Part 9 In part nine, Paul Tipton looks at bridge design and describes a new technique for improving the aesthetics, maintenance and fi t of the full arch porcelain-fused-to-metal implant retained restoration By Prof Paul Tipton, UK Introduction For many years the holy grail of implant prosthodontics has been a passive fi t of the bridge framework onto titanium implants. The original ‘Bränemark’ protocol (1981) relied heavily on this goal to ensure a long lasting restoration and longevity of the implants. Whilst a passive fi t may have been achieved on many traditional acrylic on gold, screw- retained restorations, several fur- ther diffi culties were encountered achieving the same passive fi t with a porcelain-fused-to-metal bridge. Jemt (1996) stated that in fact none of the prostheses he tested present- ed a completely passive fi t. His study indicated that a certain biologic tolerance for misfi t may be present in most restorations and in conclu- sion that an absolute passive fi t was impossible to attain for a traditional screw-retained restoration. Casting Techniques Carr (1991) and Hsu (1993) have shown that full arch impression techniques using either pick up or transfer style impression copings are also inaccurate and many hours have been spent in sectioning frame- works from an inaccurate case, pick- ing up these sections in the mouth prior to soldering in an attempt to achieve an adequately fi tting frame- work. Shiffl eger (1985) showed that large one-piece castings are not ac- curate and that these need to be sec- tioned and soldered for a more accu- rate casting and as soon as porcelain is added onto the framework, Bridger (1981) showed that the framework will distort leading to further inac- curacies in the fi t. These inaccuracies tend to be larger, more posteriorly in the arch. Cement Restoration Misch (1995) suggested that a ce- ment-retained implant supported ÿPage 36 Figure 1: Full arch porcelain-fused-to-metal bridge Figure 2: Colour shading prescription Figure 3: Preoperative OPG Figure 4: Eight implants inserted Figure 5: Pick-up impression copings Figure 6: Master model showing gold UCLA abutments Figure 7: Gold UCLA abutments in the mouth Figure 8: Copings in the mouth Figure 9: Pink porcelain framework with individual tooth preparations on master model Figure 10: Mirror view Figure 11: Fitting surface Figure 12: Pink porcelain framework placed in the mouth over copings Figure 13: Picking up the copings with Panavia – oxyguard evident Figure 14: Pink porcelain framework with Panavia and oxyguard – mirror view Figure 15: Individual crowns cemented on pink porcelain framework Figure 16: Lingual view Figure 17: Fitting surface Figure 18: Restoration cemented in mouth Figure 19: Right lateral view Figure 20: Left lateral view