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D i g i t a l w a x p r o t o t y p e s : A c l i n i c a l r e p o r t Introduction Tooth wear is a multifactorial process that can be attributed to the mechanisms of attrition, erosion and abrasion1 and can adversely impact patient satisfaction with appearance, pain levels, oral comfort and chewing capacity.2 Patients tend to seek help from dental professionals at a more advanced stage of wear, especially when it has esthetically compromised the incisal edges of the anterior teeth.3 Alteration in clinical crown height may be necessary to improve esthetics, and this is often facilitated by increasing the vertical dimension of occlusion (VDO).4 When changing the incisal position restoratively, trial restorations should be used as a guide for the patient to expe- rience function, comfort, stability and esthetics at the new increased VDO.5 Necessary changes can then be made prior to fabrication of the per- manent restorations, instead of having the final restorations created without any verification pro- cess, which can potentially lead to minor or major adjustments and possible defects of the ceramic restorations. The wax prototype can easily be modified and used as a template for fabrication. The advances in computer-aided design/ computer- aided manufacturing (CAD/CAM) tech- nology over the recent years have led to an evo- lution in restorative dentistry. Digital dentistry can be useful in full-mouth rehabilitation, as it has increased the ability of the dental team to effi- ciently create, communicate and digitally store smile designs6 and wax-ups. The final restorations can be designed and milled based on the digital smile design, or the same smile design can be used to create prototypes of the final restorations for verification purposes. While scanning and milling CAD/CAM restorations have been shown to pro- duce restorations of acceptable marginal fit below 100 μm,7 recent studies have shown that the com- bination of a conventional polyvinylsiloxane impression method and the pressed fabrication technique produces the most accurate 3-D and 2-D marginal fit.8 The purpose of this article is to describe a tech- nique of the creation of a virtual wax-up and design of a wax prototype used as a pattern for the fabrication of posterior metal–ceramic and anterior pressed lithium disilicate restorations for a patient with a severely worn dentition. Clinical report A 66-year-old woman presented to the Depart- ment of Prosthodontics at the University of North Carolina at Chapel Hill School of Dentistry, Chapel Hill, N.C., U.S., with the chief complaints of missing teeth and worn dentition (Fig. 1). Clin- ical examination found multiple teeth with mod- erate to severe attrition and erosion. The patient stated that she drank lemonade daily and had been without posterior teeth for over 5 years (Figs. 2 & 3). Previous dental history established replacement of missing teeth with a mandibular removable partial denture, which the patient had never tolerated owing to movement and food accumulation. The patient presented with excel- lent periodontal status and hygiene, and no end- odontic lesions or pathologies. After evaluation of the patient records, a digital smile design was created to evaluate the possible esthetic out- come of the treatment to include the midline, occlusal plane and ideal proportions, position, symmetry and shape of the anterior teeth. Incisal edge position was determined first9 by adding composite to the maxillary central inci- sors and evaluating the lips at rest and during smiling following the Vig and Brundo parame- ters of lip display.10 After the length had been established, a digital smile design protocol was created and width was determined using a pro- portion close to 80% of the length.11 The maxil- lary lateral incisors, canines and premolars were designed following the curvature of the lower lip and with relative tooth sizes close to the golden percentage (Fig. 4).12 The articulated casts were scanned using a 3-D scanner (3Shape D700, 3Shape, Copenha- gen, Denmark). The 3-D image of the smile design was imported into the design software (Smile Composer, 3Shape) to follow the same design during the virtual diagnostic wax-up. The virtual diagnostic wax-up was created at an increased VDO (Fig. 5). The occlusion was verified in the CAD soft- ware, and stereolithographic files were sent to the Microdental laboratory, Raleigh, N.C., U.S., to mill replicas in wax and in polymethyl meth- acrylate (PMMA) to be used as shell provisionals with a dry milling machine (Zenotec mini, Wieland Dental, Pforzheim, Germany). Upon completion of the diagnostic wax-up, the dental team developed a treatment plan that included implant-supported fixed partial den- tures for the missing mandibular left second premolar through first molar and mandibular right second premolar through second molar, full-coverage crowns for the mandibular left canine and right first premolar, full-coverage crowns for the maxillary anterior teeth, and a Journal of Oral Science & Rehabilitation Volume 3 | Issue 4/2017 43