Bite Registration Techniques

With implants these seem to vary greatly between clinicians, who express a personal preference to a wide range of bite registration materials. Suffice to say it is important that the registration is reproducible on the working cast in the first instance (Fig 5-7) and perhaps advisable that it is re-checked at the metalwork try-in appointment (Fig 5-8). A valuable hint is to only ever register the bite between the abutments or the framework and the opposing arch and not to register the bite between opposing teeth. The basis for this is that bite registration material will always distort centric occlusion, unless of course opposing dentitions are allowed to approximate without intervening material. All implant retained restorations should be constructed on an adjustable articulator using facebow registration. If facebow registration is not possible, average settings should be employed The use of a semi adjustable articulator will allow responsible assessment of the loading of the prosthesis in all excursions, an assessment of which is crucial if implants are not to be unknowingly overloaded.

Progressive Loading

The subject of provisional and progressive loading of implants has received much attention, based on the understanding that implants exposed after the normal 4-6 months osseointegration phase, are still susceptible to early overload. Misch"2 has identified differing degrees of susceptibility for implants based on bone density and has subsequently recommended varying treatment times, based on extending intervals between appointments for implants at successively increasing risk.43 The inclusion of a transitional prosthesis, fabricated in acrylic {Fig 5-9) is of considerable value. This should remain free of balancing contacts in excursive movements and non working side contacts, with a protocol that will gradually introduce favourable centric and working contacts in to a second transitional prosthesis The value of successive prostheses is perhaps anecdotal but it would seem sensible to incorporate at least one transitional prosthesis for a period of 4-12 weeks to be able to rule out undue early overload, The advantages of incorporating such a transitional prosthesis extends beyond the scope of progressive loading, offering an opportunity to both cinician and patient alike to assess aesthetics, vis-a-vis shade and tooth contour, and oral hygiene control around the fixed prosthesis (Fig 5-10). Furthermore, the subsequent storing of the transitional prosthesis may well prove

Fig 5-7 Bile registration has been carried out by the incremental build-up of Duralayâ„¢ resin, only belween the abutments and the occlusal surfaces of the opposing dentition. II is critical that bite registration is reproducible and that material is not placed between the naturally occluding dentition.

Fig 5-8 A final check of bite registration can be carried out at metawork try-in prior to final porcelain build up.

Fig 5-9 Transitional prostheses are fabricated from tooth coloured acrylic mechanically bonded to titanium cylinders. The occlusal scheme should be free of balancing, excursive and non-working side contacts.

Fig 5-10 The transitional prosthesis is screw retrievable, with access through the occlusal surfaces. Left/n s/iufor4to 12 weeks, it is possible to assess functional capacity, implant viability, hygiene control, aesthetics and phonetics.

invaluable, should it be required at a later date, it for any reason the permanent bridge has to be removed.

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