DENTAL TECHNIQUE

aAssistant PrbStudent AsscDental TechdSenior Mate

THE JOURNA

Complete denture fabrication supported by CAD/CAM

Timea Wimmer, Dr med dent,a Korbinian Gallus, BSc, CDT,b Marlis Eichberger, CDT,c and

Bogna Stawarczyk, PD Dr rer biol hum Dipl Ing (FH), MSc, CDTd

ABSTRACTThe inclusion of computer-aided design/computer-aided manufacturing (CAD/CAM) technologyinto complete denture fabrication facilitates the procedures. The presented workflow for completedenture fabrication combines conventional and digitally supported treatment steps for improvingdental care. With the presented technique, the registration of the occlusal plane, the determinationof the ideal lip support, and the verification of the maxillomandibular relationship record areconsidered. (J Prosthet Dent 2016;115:541-546)

The use of computer-aideddesign/computer-aided manu-facturing (CAD/CAM) tech-niques for fabricating fixed andremovable partial dental pros-theses has been widely re-ported.1 However, less hasbeen published on its use for

complete dentures.2-11 Initial reports were on the devel-opment and proof of concept.3-7 In 1994, the use of 3-dimensional (3D) laser lithography was described for thefabrication of complete dentures of photopolymerizedcomposite resin.5 The outer shells were fabricated by usinglaser lithography, and the inside was filled with acryliccomposite resin. A few years later, a method of duplicatinga complete denture using CAD/CAM technology with acomputerized numeric control processor for cuttingmodelling wax was presented.4 It took approximately 10years until the next study presented their CAD/CAM-aided method for the fabrication of complete dentures.Virtual flasks were constructed according to the CADdenture casts, and individualized physical flasks weremadewith a 3Dprinter.6 A recent study described a clinicalimpression procedure for obtaining the morphology ofdenture bases and the muscular and phonetic positions ofthe denture teeth. Subsequently, the recorded informationwas scanned, and the complete denture bases werevirtually designed and milled from resin.7 Nevertheless,clinical reports are scarce. In 2012, a complete denture trialplacement method using a rapid prototyping protocol waspresented and compared with a conventional trial.9 Aclinical report in 2014 dealt with theCAD/CAM fabricationof complete dentures using the AvaDent system, which

ofessor, Department of Prosthodontics, Ludwig-Maximilians University, Muistant, Department of Prosthodontics, Ludwig-Maximilians University, Munnician, Department of Prosthodontics, Ludwig-Maximilians University, Munrials Scientist, Department of Prosthodontics, Ludwig-Maximilians Universi

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allows for making the dentures in 2 clinical visits.12 At thefirst visit, the impressions, the maxillomandibular rela-tionship record, and the tooth selection are completed,and, at the second visit, the complete dentures are deliv-ered. With this technique the dentures are fabricatedwithout the need for casts, flasking, or other processingmethods. Additionally, a review was published whichfocused on the DENTCA system.13 The DENTCA system,similar to theAvaDent system, enables denture fabricationin 2 visits, although, a conventional processing techniqueis necessary. The use of CAD/CAM record bases, madewith theAvaDent system,was described for the fabricationof complete dentures.14

The conventional method of fabricating completedentures has been established for over 80 years.15 It al-lows for modification of the arrangement of teeth and theevaluation of the treatment steps before delivery.Nonetheless, the conventional method has disadvan-tages, including the number of patient visits (at least 5 areneeded plus the visits after insertion), the high treatmentcosts associated with these visits and the time- and cost-intensive laboratory work. The inclusion of CAD/CAMtechnology for the fabrication of complete dentures mayreduce cost-intensive laboratory work. The present reportof a clinical treatment provides a step-by-step description

nich, Germany.ich, Germany.ich, Germany.ty, Munich, Germany.

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Figure 1. Preoperative condition. A, Maxilla. B, Mandible.

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of a CAD/CAM-supported method for fabricating com-plete dentures.

TECHNIQUE

1. In the dental operatory, examine the patient (Fig. 1)and make anatomic impressions (Alginoplast,

Figure 2. Occlusal record. A, Occlusion rims connected with registration paste (SCo) and marked reference lines. B, Casts and occlusion rims mounted in articul

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regular set; Heraeus Kulzer GmbH) of the edentu-lous maxillary and mandibular arches and sendthem to the dental laboratory for the fabrication ofcasts and custom trays.

2. Make definitive impressions (Impregum Penta; 3MESPE) of the maxilla and mandible and send themto the laboratory for the fabrication of definitivecasts, record bases for the maxillomandibularrelationship record, and a maxillary baseplate forfacebow transfer.

3. Make the facebow and jaw relationship recordsand determine the smile line, the positions of thecanines and the midline, and the position of theanterior teeth for appropriate lip support andoptimal esthetics (Fig. 2A). Send the records to thedental laboratory so that the casts can be mountedon an articulator (Fig. 2B) and for the virtual designof the complete dentures with the software(Ceramill Mind/D-Flow; Amann Girrbach).

4. In the dental laboratory, scan the definitive castsseparately with an optical scanner (CeramillMap400; Amann Girrbach) (Fig. 3A,B). Then, scanthe casts and the occlusion rim positioned in thetransfer stand (Ceramill Transferkit; Amann Girr-bach) (Fig. 3C).

5. Import the data into the software to design com-plete dentures (Ceramill Mind/D-Flow; AmannGirrbach). Mount the scanned maxillary andmandibular casts virtually according to the scannedocclusion rim. For this, superimpose the filesdigitally and combine them by means of best-fitmatching (Fig. 4).

6. Set the occlusal plane with the help of the occlu-sion rim (Fig. 5A) and analyze the casts with thehelp of the step-by-step instruction in the soft-ware. Mark the anatomic characteristics of the castsurfaces, the position of the first premolars, andthe center line with the margin lines (Fig. 5B).

uperbite: zinc oxide eugenol bite registration paste; Harry J. Bosworthator.

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Figure 3. Screenshots of scanned casts. A, Maxillary. B, Mandibular. C,Occlusion rim between casts.

Figure 4. Virtual mounting of casts by means of best-fit matching.

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Determine the boundary line for the anterior teethon the basis of the maxillary record base. With theentered information, the software calculates thecommon arrangement lines and suggests anapplicable set of artificial teeth (Fig. 5C). Thedeposited artificial teeth are conventionally man-ufactured teeth made of acrylic resin from differentmanufacturers and not produced by CAD/CAMtechnology.

7. Select the preferred artificial teeth and let thesoftware automatically arrange them in their cor-rect position (Fig. 5D).

8. Design the gingival parts of the dentures on thebasis of the suggestion of the software with the

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help of the different tools provided, for example, avirtual wax knife or paint brush (Fig. 5E).

9. Send a preview of the virtual arrangement to theclinician for evaluation.

10. Shorten the basal surfaces of the artificial teethvirtually according to the contour of the alveolarridges and the minimum denture thickness andprovide them with retention for later fixation in thedenture bases. Generate the data sets for thedenture bases and the tooth sockets.

11. Mill the denture bases with a 5-axis milling ma-chine from a gingiva-colored wax blank (CeramillD-Wax, Ceramill Motion 2; Amann Girrbach).

12. Modify the conventional denture teeth accordingto the individual clinical situation. For this, mountthem in a special blank/device and mill their basalsurfaces corresponding to the prior computation.(Ceramill Motion 2; Amann Girrbach).

13. Wax the adapted denture teeth into the sockets ofthe wax bases (Fig. 6) and evaluate the completedtrial denture in the conventional articulator (Fig. 7).Send the trial denture to the clinician.

14. In the dental office, evaluate the trial dentures inthe patient’s mouth. Make adjustments to thearrangement in the conventional way, if necessary.

15. Send the trial dentures to the dental laboratory fortheir completion by flasking.

16. Deliver the completed dentures (Figs. 8, 9).

DISCUSSION

It has been 20 years since the implementation of CAD/CAM technology in the fabrication of complete dentureswas reported. In the last few years, significant advance-ments have taken place in this field, and the first casereports have been published.12,13

The presented concept of Ceramill Full DentureWorkflow incorporates CAD/CAM technology into theworkflow of fabricating complete dentures. However,incorporation refers only to the tooth arrangement, the

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Figure 5. Digital workflow of designing complete dentures. A, Setting occlusal plane. B, Cast analysis. C, Proposal for tooth arrangement. D, Articulatorsettings. E, Proposal for gingival design. F, Milling data for maxillary complete denture including tooth sockets.

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milling of the wax trial bases, and the modification of thedenture teeth so that they can be inserted into the toothsockets of the bases with wax and without additionalgrinding.

Compared with the completely conventional tech-nique of fabricating dentures, this procedure has severaladvantages. Scanning the maxillary and mandibular castsand importing them into the software allows for betterdetection and visualization of the morphology of theedentulous maxillary and mandibular arches. Virtualsectional views facilitate the identification of anatomiccharacteristics, and, with the help of a software algo-rithm, the midlines of the alveolar ridges, for example,can be identified. A further advantage is that the virtual

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arrangement of the artificial teeth is a reproducible pro-cedure enabling predictable results. With the help of thevirtual articulator, static occlusion and the dynamicrelation of the dentures are considered during digitalarrangement. Also, the digitized maxillary record basecan be taken into account, particularly for anterior teetharrangement. With the correct incisal edge position of themaxillary teeth, ideal lip support can be realized. More-over, the maxillary record base will be used to establishthe plane of occlusion.

Posterior teeth can be arranged according to the occlusalconcept of the manufacturer. Thus, an ideal contact situa-tion can be achieved. The arrangement can be performed insignificantly less time in comparison with the manual

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Figure 6. Milled wax dentures. A, Maxillary upper surface with teeth inserted. B, Maxillary intaglio. C, Mandibular upper surface with teeth inserted. D,Mandibular intaglio.

Figure 7. Milled wax dentures in articulator.

Figure 8. Completed dentures.

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arrangement. Additionally, the time-consuming procedureofmanualwaxing is eliminated. Thepolished surfaces of thedenture bases can be easily designed with differentanatomic features, for example, stippling and rugae. Apreview of the virtual arrangement can be sent to theclinician for approval. If modifications of the tootharrangementare required, this ispossible.Also, for example,for adjustments for esthetic reasons, the arrangement canbe superimposed with the digitized record bases.

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At the trial placement, minor adjustments of thearrangement can be made in the conventional way. Incase of extensive modification, the wax denture base canbe milled once more according to the required arrange-ment, and a second evaluation appointment is possible.Indeed, in the presented patient case, increasing thevertical dimension of occlusion was necessary. The dentaltechnician unscrewed the anterior guide pin and

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Figure 9. A, B, Patient with complete dentures.

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remounted the mandibular cast in the articulator with theocclusion rim. As a facebow record had been made,increasing the vertical dimension did not entail errors inthe occlusion. The situation was transferred into thevirtual articulator, and a new mandibular tootharrangement was designed with the software.

The virtual design of complete dentures allows forconsistent thickness of the bases. The material thicknesscan be adjusted to the material and kept minimal,allowing for the function and durability of the dentures.Furthermore, a consistent material thickness minimizesdeviations in the contact relationships of the teeth, forexample, due to polymerization shrinkage, and enablesan improved fit to the mucosa, which is important fordenture retention.16-18

The dentures may be easily duplicated with the digitaldata and research in this field is facilitated.10 With thesystem used here (Ceramill Full Denture Workflow),complete dentures can be digitally completed by millingthem from prepolymerized acrylic resin blocks. However,the manufacturer does not currently enable this optionbecause of the risk of remake. The source of error is themanual maxillomandibular relationship record, which is

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difficult and fault-prone. Development should focus onthis field. Also, the problem concerning the durability ofthe bond between the base and the teeth has not beensolved.

Clinical and laboratory research is necessary to vali-date the new computer-aided treatment procedures forthe fabrication of complete dentures.10

SUMMARY

Incorporation of CAD/CAM technology into the designand fabrication of complete dentures helps to simplifylaboratory work and standardize complete denturefabrication. Ceramill Full Denture Workflow is a CAD/CAM-based system. With the help of proprietary soft-ware, the denture teeth can be arranged and basesdesigned. Dentures bases are milled from a wax blank,allowing for adjustments after clinical evaluation.

REFERENCES

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7. Goodacre CJ, Garbacea A, Naylor WP, Daher T, Marchack CB, Lowry J.CAD/CAM fabricated complete dentures: concepts and clinical methodsof obtaining required morphological data. J Prosthet Dent 2012;107:34-46.

8. Zhang YD, Jiang JG, Liang T, Hu WP. Kinematics modeling and experi-mentation of the multi-manipulator tooth-arrangement robot for full denturemanufacturing. Journal of medical systems 2011;35:1421-9.

9. Inokoshi M, Kanazawa M, Minakuchi S. Evaluation of a completedenture trial method applying rapid prototyping. Dent Mater J 2012;31:40-6.

10. Bidra AS, Taylor TD, Agar JR. Computer-aided technology for fabricatingcomplete dentures: systematic review of historical background, current status,and future perspectives. J Prosthet Dent 2013;109:361-6.

11. Lebon N, Tapie L, Vennat E, Mawussi B. Influence of CAD/CAM tool andmaterial on tool wear and roughness of dental prostheses after milling.J Prosthet Dent 2015;114:236-47.

12. Infante L, Yilmaz B, McGlumphy E, Finger I. Fabricating complete dentureswith CAD/CAM technology. J Prosthet Dent 2014;111:351-5.

13. Kattadiyil MT, Goodacre CJ, BabaNZ. CAD/CAM complete dentures: a reviewof two commercial fabrication systems. J Calif Dent Assoc 2013;41:407-16.

14. McLaughlin JB, Ramos V Jr. Complete denture fabrication with CAD/CAMrecord bases. J Prosthet Dent 2015;114:493-7.

15. Jacob RF. The traditional therapeutic paradigm: complete denture therapy.J Prosthet Dent 1998;79:6-13.

16. Artopoulos A, Juszczyk AS, Rodriguez JM, Clark RK, Radford DR. Three-dimensional processing deformation of three denture base materials.J Prosthet Dent 2013;110:481-7.

17. Darvell BW, Clark RK. The physical mechanisms of complete dentureretention. Br Dent J 2000;189:248-52.

18. Chen JC, Lacefield WR, Castleberry DJ. Effect of denture thickness and curingcycle on the dimensional stability of acrylic resin denture bases. Dent Mater1988;4:20-4.

Corresponding author:Dr Timea WimmerGoethestraße 70, 80336 MunichGERMANYEmail: timea.wimmer@med.uni-muenchen.de

Copyright © 2016 by the Editorial Council for The Journal of Prosthetic Dentistry.

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