Dental Tribune Untited Kingdom Edition

April 16-22, 201220 Lab Tribune United Kingdom Edition various composite restora- tions placed throughout the years (Fig 5). A lingual amal- gam restoration in tooth #12 and composite restorations in teeth #23, 21, 11 and 13 showed recurrent decay that was diagnosed with digital X- rays. She possessed a negative medical history and good oral hygiene with resultant peri- odontal health and asympto- matic teeth. Treatment options of zirconia or porcelain-fused- to-metal crowns or CAD/CAM all-ceramic restorations were discussed with the patient. Ultimately, CAD/CAM all- ceramic restorations were tested. When proper prepa- ration and occlusal design considerations are followed, properly placed CAD/CAM- designed and -milled resto- rations have been extremely successful. The patient made a preparation appointment, during which the existing restorations were removed, and teeth #23 to 13 were pre- pared for all-ceramic veneer restorations, following ac- cepted CAD/CAM glass-ce- ramic preparation guidelines (Fig 6): adequate clearance, rounded internal aspects, and equi-gingival butt-joint mar- gins were ensured. Once the preparations were complet- ed, conventional impressions were taken and poured in high-quality, laser-reflective dental stone. Laboratory communication The dentist is to the dental technician what the architect is to the builder. Each has a primary role in indirect re- storative dentistry, which is to imitate natural function and aesthetics perfectly and translate that into a restora- tive solution. The communi- cation between the clinician and technician entails a thor- ough transfer of information, including functional compo- nents, occlusal parameters, phonetics and aesthetics, and continues throughout the restorative process, from the initial con- sultation through treatment planning and provisionalisa- tion to final placement. The primary and conven- tional communication tools between the dentist and tech- nician are: • Photography • written documentation • impressions of the patient’s existing dentition • clinical preparation • opposing dentition This information is used to create models, which are mounted on an articulator to simulate the mandibular jaw movements. Traditional indirect restora- tive process The indirect restorative pro- cess involves the following steps: 1The clinician prepares the case according to the ap- propriate preparation guide- lines, takes the impressions, sends these and other critical communication aspects to the laboratory, and the laboratory receives all the materials from the dentist. 2Then, the impressions are poured, models mounted, and dies trimmed. 3Appropriaterestorations— layered, pressed, milled, cast, or combinations—are made. However, as restorative dentistry shifts further into the digital era, clinicians must change their perceptions and definitions of the dental laboratory. Traditionally, a laboratory is the site that re- ceives and processes patient impressions and returns the completed restorations to the clinician, who adjusts and delivers them to the patient. Similar to how the Internet has transformed the commu- nication landscape, the pos- sibility of using CAD/CAM- restoration files electronically has spurred evolutions in the way dental restorative teams perceive and structure the dentist–laboratory relation- ship. The digital process When the E4D LabWorks sys- tem (D4D Technologies) was introduced in 2008 (Fig 7), it was the first computerisation model to present a real 3-D virtual model accurately and account for the occlusal ef- fect of the opposing and adja- cent dentition automatically. It enables the user to design 16 individual, full-contour, anatomically correct teeth si- multaneously. The device con- denses the information from a complex occlusal case and displays it in a user-friendly format that allows clinicians with basic knowledge of den- tal anatomy and occlusion to modify the design. Once this has been completed, the in- formation is sent to the auto- mated milling unit. The innovation of digitally designed restorations meant that some of the more me- page 19DTß Fig. 5 Pre-existing clinical condition of maxillary anterior teeth to be restored Fig. 6 Veneer preparations for the anterior restoration Fig. 7 E4D Lab- Works system used for the scan, design, and milling of the veneer restorations Fig. 8 Computerised image of digital 3-D model Fig. 9 Computerised 3-D digital composite file, showing preparation, provisional mod- els and digital restoration design Fig. 10 Final digital restorations, with cut-back design for the micro-layering of enamel ceramics