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CAD/CAM - international magazine of digital dentistry

I 09 CE article _ practical lessons in CAD/CAM I CAD/CAM 3_2013 One study found a success rate of 90.4 per cent after 10 years with older feldspathic ceramics as well as older milling and design technology.18 In this case, the patient was not happy with the aesthetics of the amalgam restorations, and she had recurrent caries on the mesial of tooth #13. The E4DDentistSystemwasusedtomakeadigitalmodel, and the design software proposed well-contoured, anatomicalrestorationsthatweremilledoutofe.max CAD HT A2 blocks. For delivery, the restorations were prepared by etching with 4.9 % hydrofluoric acid for 20 seconds and silanating for 60 seconds with Monobond-Plus (Ivoclar Vivadent). The tooth was pumiced clean; Optibond XTR (Kerr) was applied and curedfor20seconds;andNexus3resincement(Kerr) was used (Figs. 4–6). Despite the benefits of onlays, single-unit crowns arestillthepreferredrestorationforthegeneralden- tist, and the E4D Dentist System fabricates excellent restorations with a short learning curve. With the strength of IPS e.max, predictable restoration of sec- ond molars using the E4D Dentist System is possible (Figs. 7–9). Oncethelearningcurveofsingle-unitrestorations is mastered, it will not be long before the benefits of the E4D Dentist System become apparent for more complicated cases. A 37-year-old male presented for a consult for dentures. He had been to several dentists and an immediate denture was the treat- ment plan he had selected. He presented with severe acid erosion and abrasion from a combination of gastroesophageal reflux disease (GERD) and bruxism (Figs.10 & 11). Occlusal examination revealed a lack of anterior guidance and posterior support. The lateral ptery- goids were sensitive to palpation, and upon visual examination it was noted that he had hypertrophic masseters. Lip commissures were folded and he appeared to have a collapsed vertical dimension of occlusion (VDO). He did not close in a repeatable position and had a severe anterior deviation from centric relation. Whenevaluatingthelocationofthegingivalmar- gins it was determined that compensatory eruption hadtakenplace.However,basedontheclosestspeak- ing space during the production of sibilant sounds, the patient had excess freeway space. It was determined that the patient lost vertical dimension of occlusion, and therefore compensa- toryeruptiondidnotkeepupwiththerateoferosion. Two centric-relation (CR) records were made using bimanualmanipulation,acustomtriadjigandarigid bite material. The case was mounted on a semi-ad- justablearticularincentricrelationandthemounting was verified with the second CR record. Itwasdecided(basedonfreewayspace,aesthetics and phonetics) that to recapture the lost VDO the pa- tientneededtobeopened2.5mmintheanterior;this correlatedtoaround1mmintheposterior.Adiagnos- tic wax-up was made. The teeth were prepared and temporized based on the diagnostic wax-up (Figs. 12 &13).Thepatientwaskeptintemporariesforsixweeks to verify tolerance of the new vertical dimension, phonetics(particularly“F”and“S”sounds)andCR. In the provisionals, anterior guidance was estab- lished with no balancing interferences during lateral excursive movements. CR was stable and at the end of the six-week trial period the patient was pain- free upon palpation of his lateral pterygoid muscles, Figs. 12 & 13_After a diagnostic wax-up was made, the teeth were prepared and temporized. Fig. 14_The E4D Dentist System clone feature copies the occlusion and anatomy of the temporaries exactly. Fig. 14 Fig. 13Fig. 12