Complete Oral Rehabilitation With ImplantsUsing CAD/CAM Technology,

Stereolithography, and Conoscopic HolographyRobert M. Bentz, DMD,* and Stephen F. Balshi, MBE†

Technology is changing the waypractitioners are able to plantreatment for their patients and

is allowing them to offer solutions totheir patients that were not availablebefore. Specifically in the area of im-plant dentistry, dentists and techni-cians alike are able to use medicalimaging to help idealize implant loca-tions as they relate to the bone andmucosa. Ultimately, preplanning of pa-tient treatment using medical imagingleads to more predictable esthetic andfunctional prosthetic rehabilitations.

The patient treatment described inthis report uses various modalities atvarious stages to deliver the patient’sdesired final result. Computed tomog-raphy (CT) is a medical imaging tech-nique in which images are digitallyacquired in slices, which are reformat-ted into virtually any 2-dimensional or3-dimensional (3D) perspective.1 Ste-reolithography (STL),2– 4 sometimesreferred to as 3D printing, is a rapidprototyping technique that takes a geo-metric definition from a medical im-age volume, like a CT scan, and thenuses a 3D biomedical visualizationsoftware package to convert it into a

suitable 3D format that can be pro-duced. Conoscopic holography5 is anoptical scanning technique based onoptical propagation through birefrin-gent crystals where the projectedand reflected beams travel the samelinear pathway to and from thescanned object. All of these modali-ties in concert with one another al-lowed for the delivery of maxillaryand mandibular implant-supportedfixed prostheses in the following pa-tient report.

CASE REPORTSPatient

A 64-year-old white female pre-sented to a private practice specializ-ing in prosthodontics. At her initialpresentation, she was completelyedentulous with a high smile line (Fig.1). Her current removable completedentures were ill-fitting, and her chiefcomplaint was that she “no longer feltcomfortable in public.” The patientclaims she had been wearing denturesfor 40 years. Her medical history isnoncontributory, only suffering fromsmall bouts of arthritis and low bloodpressure.

A cone beam computed tomogra-phy scan (i-CAT; Imaging SciencesInternational, Hatfield, PA) revealedatrophic ridges and the poor prognosisfor removable prosthetics (Fig. 2). Thepatient also had a Class III occlusalscheme that was determined via diag-nostic models and a lateral cephalo-metric radiograph.

A comprehensive treatment plan wasdeveloped between the prosthodontistand the laboratory technician whichincluded maxillary- and mandibular-guided implant placement. The patientaccepted the treatment plan offeredwhich culminated with maxillary andmandibular implant-supported screw-retained final restorations built withmilled titanium frameworks.

Presurgical Procedures

Treatment began with the fabrica-tion of new removable prostheses. It isthe authors’ opinion that all dental im-plant treatment must be prostheticallydriven. These new removable pros-theses act as a template for the de-sign of the final prostheses in thisparticular guided surgical protocol(NobelClinician; Nobel Biocare,Yorba Linda, CA).6 – 8

*Prosthodontist, Founder and CEO of Bentz Dental Implantand Prosthodontic Center, East Norriton, PA.†Biomedical Engineer, President, CM Prosthetics Inc., FortWashington, PA; Director of Research, PI Dental Center,Institute for Facial Esthetics, Fort Washington, PA.

Reprint requests and correspondence to: Stephen F.Balshi, MBE, CM Prosthetics, Inc., 467 PennsylvaniaAve., Suite 100, Fort Washington, PA 19034, Phone:(215) 646-7362, Fax: (215) 461-1822, E-mail:balshi2@aol.com

ISSN 1056-6163/12/02101-008Implant DentistryVolume 21 • Number 1Copyright © 2012 by Lippincott Williams & Wilkins

DOI: 10.1097/ID.0b013e318243a1aa

A 64-year-old totally edentulousfemale initially presented with ill-fitting removable prostheses. A com-prehensive treatment plan with dentalimplants was accepted by the patient.Clinical and laboratory procedureswere executed using various computertechnologies including computed to-mography, rapid prototyping, and

optical scanning using conoscopicholography. A review of the pa-tient’s treatment and various modal-ities used are the focus of this patientreport. (Implant Dent 2012;21:8–12)Key Words: dental implants, os-seointegration, surgical template

8 COMPLETE ORAL REHABILITATION WITH IMPLANTS • BENTZ AND BALSHI

Radiopaque markers (gutta-percha;Coltene Whaledent, Cuyahoga Falls,OH) were embedded into the remov-able prostheses with each site about1.5 mm in circumference. A polyvinylsiloxane (Regisil 2x; Dentsply, Mil-ford, DE) centric occlusal index wastaken to stabilize the removable pros-theses during the forthcoming CTscanning procedures.

The dual CT scan technique asso-ciated with this guided surgery proto-col was accomplished, and the digitalimaging and communications in med-icine (DICOM) files were exported tothe diagnostic and virtual treatmentplanning software (NobelClinician;Nobel Biocare, Yorba Linda, CA).The maxillary and mandibular virtualsurgeries were designed and approvedby both the prosthodontist and the lab-oratory with the final prostheses inmind. The maxillary virtual implantplanning was designed with 8 externalconnection implants (NobelSpeedyGroovy; Nobel Biocare, Yorba Linda,CA) and 4 anchor pins. Six of theseimplants were planned in the anteriormaxilla, and 2 of these implants wereplanned in the pterygomaxillary re-gion.9,10 In the mandible, 6 external

connection implants (Brånemark Sys-tem MKIII; Nobel Biocare, YorbaLinda, CA) and 5 anchor pins werepositioned (Fig. 3).

The computer-assisted designfiles of the maxillary and mandibularvirtual plannings were transmittedthrough the internet to the productionfacility (NobelProcera, Mahwah, NJ)where those files dictated the stereo-lithic construction of the surgicaltemplates. Also fabricated at the pro-duction facility were stereolithic du-plicates of the patient’s removableprostheses that were part of the dualCT scan protocol. The 2 templates andduplicate dentures were sent to thelaboratory for construction of maxil-lary and mandibular all-acrylic resinprovisional prostheses.

The laboratory used the surgicaltemplates to retroengineer an implant-level maxillary and mandibular mastercast with a soft tissue replication. Thestereolithic duplicate dentures wereused in conjunction with the polyvinylsiloxane occlusal index (from the dayof the CT scan) to position the mastercasts in an articulator. This techniqueallows for precise replication of whatexists clinically with the existing re-

movable prostheses. The laboratorytechnician then chose appropriate col-lar heights for transmucosal abutments(Multi-Unit; Nobel Biocare, YorbaLinda, CA), which were positioned foreach of the 14 implants. The prostheticcylinders (Temporary Titanium Cop-ing Multi-Unit; Nobel Biocare, YorbaLinda, CA) were adjusted as necessaryfor the all-acrylic resin provisionalprostheses, and teeth were positionedin relationship to the master casts ex-actly how the teeth were positioned inthe stereolithic duplicate dentures. Be-fore sending the completed laboratorywork back to the prosthodontist, in-dexes were fabricated on the articula-tor between each surgical template andthe opposing duplicate denture.

Implant Placement and ProvisionalProsthesis Delivery

The patient was anesthetized with8 carpules of 1.8 mL Bupivacaine1:200,000 (Arestream Health; Cam-bridge, ON). The mandibular surgicaltemplate was carefully positioned withthe laboratory-fabricated index againstthe maxillary removable denture. Af-ter the anchor pins were placed, the 6external connection implants wereinstalled with the depth-controlleddrilling system through the surgicaltemplate (Fig. 4). The surgical tem-plate was then removed, and themandibular removable denture wasreplaced to create the reference fordelivery of the maxillary surgical tem-plate. Anchor pins were installed tosecure the maxillary surgical templateand allow for the placement of 8 ex-ternal connection implants.

The transmucosal abutments thatwere used on the master cast to fabri-cate the provisional prostheses weresterilized and then transferred to thepatient. These abutments will remainin place as long as the implants areclinically successful. Keeping theimplant-abutment interface intactfrom baseline reduces the effect of themicrogap that occurs with removaland replacement of abutments in con-ventional 2-piece implant systems.11,12

The all-acrylic resin provisional pros-theses that were prefabricated in thelaboratory were delivered with retain-ing screws (Prosthetic Screw Multi-

Fig. 1. Frontal view of patient at initial presentation illustrating worn and ill-fitting removabledentures.Fig. 2. Panoramic radiograph from the pretreatment cone beam computed tomography scanreveals atrophied edentulous arches.Fig. 3. Screen capture from the NobelClincian software of finalized mandibular virtual implantplanning with 6 implants and 5 anchor pins.Fig. 4. Osteotomy preparation for a Brånemark System MKIII RP implant in the mandibularanterior.

IMPLANT DENTISTRY / VOLUME 21, NUMBER 1 2012 9

Unit; Nobel Biocare, Yorba Linda,CA), thereby immediately loading themaxillary and mandibular implants(Fig. 5A and B).

Final Prosthesis Construction

Three months after implant place-ment, the patient presented for finalimpressions. As observed in the pan-oramic radiograph 48 hours after im-plant placement (Fig. 5B), not all thetemporary cylinders were seated fullyonto the abutments and therefore theprovisional prosthesis could not beused as the impression splint to createan accurate master cast. It was notedthat one of the maxillary implants wasnot integrated, and it was removed.The appropriate temporary cylinderin the all-acrylic resin provisionalprosthesis was removed, and the pros-thesis was refined and polished. Noprovisions for replacement of the im-plant were made as it was determinedthat the final restoration would be ad-

equately supported by the remaining 7implants.

Direct transfer copings (OpenTray Impression Coping Multi-Unit;Nobel Biocare, Yorba Linda, CA)were installed and connected withdental floss and pattern resin (GCResin; GC America, Alsip, IL) to sta-bilize the impression. The newly fab-ricated impression splint was capturedin the impression. Abutment analogs(Multi-Unit Abutment Replica; NobelBiocare, Yorba Linda, CA) were in-stalled into the direct transfer copings.A soft tissue replication material (Gin-gifast Rigid; Zhermack, Eatontown,NJ) was used followed by minimalexpansion die stone (Die-Keen;Heraeus Kulzer, South Bend, IN) tofabricate the master casts. These castswere articulated using the patient’sprovisional restorations as the jaw re-lationship was to be replicated in thefinal restorations. Esthetic modifica-

tions from the provisional prostheseswere noted for the laboratory.

The final prosthesis design forboth the maxilla and the mandible wasa computer numeric controlled(CNC)-milled titanium framework(NobelProcera Implant Bridge; NobelBiocare, Mahwah, NJ) veneered withthermocure acrylic resin (Classico;Artigos Odontologicos Classico, SaoPaulo, Brazil) and acrylic dentureteeth (Blueline; Ivoclar, Amherst,NY). It has been well documentedin the literature that CNC-milledframeworks for edentulous archeshave higher accuracy of fit to themaster cast than traditional castingtechniques.13–16

Facial and occlusal matrices(Zetalabor; Zhermack, Eatontown,NJ) were made to record tooth posi-tion to fabricate an acrylic-resin pat-tern of the framework. The same typeof temporary cylinders used in the pro-visional prostheses was used to buildthe pattern and secure it to the mastercast. The temporary cylinders wereconnected with autopolymerizingmethylmethacrylate resin (UnifastTrad; GC America, Alsip, IL). Theresin patterns were designed to con-sider strength of the milled titaniumframework and space for veneeringmaterials.

The maxillary pattern was con-nected to the specific holder for theoptical scanner (NobelProcera Scan-ner; Nobel Biocare, Yorba Linda, CA)with old lab burs and pattern resin.Specific abutment replica position lo-cators were installed onto the mastercast, which was then secured to thescanner. These locators were scannedto determine the precise position of thereplicas in the master cast. A similarposition locator that mates with thetemporary cylinder in the resin patternwas connected. These positions wereacquired by the optical scanner aswell. Finally, the resin pattern itself isscanned to acquire its 3D shape as itrelates to the cylinder positions. Thisis done in 2 stages: the tissue side isscanned first, followed by the toothside. The scanner holder has 3 refer-ence “dimples” that allow these 2stages of scanning to be merged to-

Fig. 5. A, Frontal view of maxillary and mandibular all-acrylic resin screw-retained provisionalprostheses. B, Panoramic radiograph 48 hours after implant placement. One temporarycylinder in each arch is not completely seated onto the abutment despite all screws tightenedto the recommended 15 N/cm torque.

10 COMPLETE ORAL REHABILITATION WITH IMPLANTS • BENTZ AND BALSHI

gether to create the STL file (Fig. 6Aand B) that is ultimately sent to theproduction facility for copymilling.

The STL file can be modified in thesoftware to trim any excess materialthat was picked up from the connec-

tion of the resin pattern to the scannerholder. The same scanning processwas completed for the mandibularpattern.

A solid block of titanium grade 2is milled according to the STL file thatis transmitted to the production facility(NobelProcera, Mahwah, NJ). Figure7, A and B, shows the CNC-milledimplant bridges placed onto the mastercasts to confirm seat. The frameworkswere roughened with old or dull bursto increase the mechanical retention ofa pink opaquer (Gradia; GC America,Alsip, IL). The denture teeth were setinto position in wax which was thentried clinically to obtain patient accep-tance. After final approval, the prosthe-ses were processed with the thermocureacrylic resin. The prostheses were thendelivered, and the fit was checkedclinically and radiographically. Pros-thetics screws were torqued to the rec-ommended 15 N/cm. The patient hasbeen followed for routine hygienemaintenance for the past 2 years (Fig.8A and B).

CONCLUSION

The patient treated in this reportexperienced a life-changing experi-ence with dental implant therapy in aminimally invasive treatment ap-proach. The combination of medicalimaging, CAD software, and stereo-lithography allowed for the design of asurgical template that resulted in flap-less dental implant placement. Defin-itive prostheses were made using thelatest optical scanning technologyavailable, resulting in passive-fittingframeworks. Blending of these tech-nologies resulted in a stable andpredictable reconstruction for thisedentulous patient.

DISCLOSURE

The authors claim to have consult-ing fees and/or honoraria and/or sup-port for travel “not for this study butfor lectures on various Nobel Biocareproducts at study clubs or annual ses-sions,” an ongoing relationship withNobel Biocare.

Fig. 6. A, Screen capture from the NobelProcera software scanning module illustrating thetissue surface of the resin pattern. Part of the pattern resin connection to the holder on thepatient’s right side was picked up during the scanning procedures. B, Screen capture fromthe NobelProcera software scanning module illustrating the tooth surface of the resin pattern.Part of the pattern resin connection to the holder on the patient’s right side was picked upduring the scanning procedures.

Fig. 7. A, Right lateral view of articulated master casts with CNC-milled titanium frameworksin place. B, Left lateral view of articulated master casts with CNC-milled titanium frameworksin place.Fig. 8. A, Panoramic radiograph 2 years after implant placement. B, Frontal view of patient at2 years after implant placement with definitive CNC-milled titanium frameworks.

IMPLANT DENTISTRY / VOLUME 21, NUMBER 1 2012 11

ACKNOWLEDGMENTS

The authors thank the staff of BentzDental Implants and ProsthodonticCenter for the care of this patientand the dental technicians at CMProsthetics, Inc., for the fabricationof the definitive implant-prosthodonticreconstructions.

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