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CDE0211

I 11 MICD _ occlusal force management I cosmeticdentistry 2_2011 incisal to the original vertical stops on the anterior teeth, some excess bonding cement required removal to maintain the vertical dimension. Next, protrusion and latero- trusive excursions were ana- lysed with the T-Scan III system to determine whether extreme forces were present at the in- cisal edges or on the lingual functional inclines of the ve- neers. The maxillary anterior lingual surfaces provide tooth- bornerampsforthelowerante- rior teeth to glide over during mandibular excursions. Con- trolling any extreme forces on the lingual veneer ramps will aid in ceramic material longe- vity. Dynamic excursive func- tions are recorded by instructing the patient to occlude through the T-Scan III sensor into his/her maximum inter-cuspal position (MIP), holding the teeth together for one to two seconds, then com- mencing an excursive movement across the guid- ingteeth.20–22 Right–leftandprotrusiveexcursions canberecordedforforceanalysis.Onlytheprotru- sive excursion will be discussed here. Figure 15a illustrates the first articulating paper labelling of the protrusive movement made as the mandibular incisors leave the MIP and travel towards the in- cisal edge. Note that there is a dark long protrusive track line on the distal-incisal aspect of tooth #12, a shorter line on the distal of tooth #11 and a hor- izontal line on the incisal edge of tooth #11. De- spite the appearance of these ink representations, the paper labelling offers no indication as to whether any high force region even exists. Figures 15b and c describe the movement as recorded by the T-Scan III. As the excursion pro- gresses after the patient leaves the MIP position (Fig. 15b) and transitions onto the anterior teeth, tooth #11 becomes very forceful near the incisal edge (tall pink force column) as the protrusive movement advances to include only the incisors (Fig. 15c). If left untreated, possible fracture of the distal incisal edge of this veneer could result from the extreme force applied each time the mandible protrudes. To correct this excessive protrusive force, ad- justments guided by the recorded force data were employed. The disto-incisal paper track line was occlusallyadjustedwithamediumcoarsediamond bur with water spray. Following this first adjust- ment sequence, a new recording was made to as- certainnewforceandtimechangesresultantfrom thepreviousadjustment.Thesenewforceandtime aberrations were isolated, labelled and adjusted. This was repeated until no extreme occlusal forces were present throughout the duration of the pro- trusive excursion and moderate to low forces were shared between the guiding inclines and incisal edges. Figures 16 and 17a show the mid-treatment andfinalarticulatingpapermarkingsofprotrusive movement. Note that in Figures 15a, 16 and 17a, the paper markings offer no quantifiable force or time information to guide corrective adjustments. Figures 17b to d illustrate that in the corrected fi- nal protrusive movement there are shared force transitions between teeth #11 and 21 all through the movement. The computer-guided result has protrusive contacts that never reach the poten- tially damaging force levels seen preoperatively (Fig. 15b). Thiscaseillustratestheuseofcomputer-guided occlusal analysis with adhesive restorations to minimiseexcessiveocclusalforcesthatresultfrom the all-ceramic restoration placement, where the bonding process must precede all occlusal ad- justments. This reversal of the conventional place- ment process (absent of inter-occlusal remounts) can introduce significant occlusal errors that are poorly discerned with articulating paper. Com- Fig. 17a_End of treatment paper markings of protrusive movement. Fig. 17b_Corrected post-op early protrusion. Fig. 17c_Corrected post-op mid-protrusion. Fig. 17d_Corrected post-op end protrusion. Fig. 17d Fig. 17bFig. 17a Fig. 17c