DENTAL TECHNIQUE

aAssociate Prpractice, VenbFaculty, Dep

THE JOURNA

A technique for immediately restoring single dental implantswith a CAD-CAM implant-supported crown milled from

a poly(methyl methacrylate) block

Periklis Proussaefs, DDS, MSa and Abdulaziz AlHelal, BDS, MSb

ABSTRACTThis technique is used when a single dental implant is placed. A stent made of autopolymerizedacrylic resin was used to transfer the implant position to the laboratory. Once the implant positionwas transferred, the stone cast was scanned, and a computer-aided design and computer-aidedmanufacturing (CAD-CAM) interim implant-supported crown was milled from a poly(methylmethacrylate) (PMMA) block. A titanium insert, in contact with the implant platform and not thePMMA material, was used to support the crown. The interim prosthesis was then placed intraorally.The soft tissues were sutured, and the interim prosthesis was left for a period of at least 3 months toconfirm osseointegration and allow the soft tissue to heal. A CAD-CAM titanium impression copingwas made and used for the definitive impression. The contours of the impression coping wereidentical to the contours of the interim restoration. The data of the digital design of the interimprosthesis were saved, and the definitive prosthesis was fabricated with contours identical to thoseof the interim prosthesis. (J Prosthet Dent 2018;119:339-44)

An interim implant-supportedprosthesis is beneficial in con-firming esthetics, contours,1-3

and peri-implant tissue architec-ture.4-8 Proussaefs7 suggestedthe term “guided tissue heal-ing,”where an interim implant-supported prosthesis was usedto guide the soft tissue archi-tecture. Interim restorations forsingle dental implants can beeffectively provided on the dayof surgery.8-12

Various methods have been suggested for transferringthe soft tissue contours to the laboratory, including theuse of the interim prosthesis as a custom impres-sion coping,8,13 intraoral fabrication of a custom impressioncoping,12,14,15 implementation of digital scanning technol-ogy,16 and fabrication of milled impression copings.6,7

Joda17 reported that soft tissue tends to collapse after theinterim prosthesis is removed. Therefore, accurate dupli-cation of the peri-implant soft tissue could be difficult withconventional prefabricated impression copings.

The purpose of this article was to describe a techniquewhere an interim screw-retained implant-supportedcrown could be fabricated from a milled poly(methylmethacrylate) (PMMA) block the same day of implantsurgery with the use of a transfer stent (TS).18 In addition,a customized impression coping could be milled from a

ofessor, Advanced Education Program in Implant Dentistry, Department otura, Calif.artment of Prosthetic Dental Sciences, College of Dentistry, King Saud Un

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titanium blank, a process associated with superior accu-racy.19 The contours of the custom impression copingcould be designed to be identical to those of the interimprosthesis.

TECHNIQUE

1. Evaluate the soft tissue around the edentulous areafor signs or symptoms of pathosis (Fig. 1). Makecomplete-arch preliminary impressions preopera-tively of the patient’s maxillary and mandibulararches with polyvinyl siloxane (PVS) impressionmaterial (Genie VPS; Sultan Healthcare). Make aninterocclusal record with PVS occlusal registrationmaterial (Exabite II NSD; GC America, Inc) at themaximum intercuspation position.

f Restorative Dentistry, Loma Linda University, Loma Linda, Calif; and Private

iversity, Riyadh, Saudi Arabia.

339

Figure 1. Preoperative intraoral view. Figure 2. Diagnostic preoperative stone cast. Transfer stent made oflight-polymerized acrylic resin. Hole made through stent at area ofmissing tooth. Oversized surgical drill used to prepare simulatedosteotomy of stone cast.

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2. Use the preliminary impressions to fabricatediagnostic stone casts. Use the diagnostic casts tofabricate a TS made of light-polymerizing acrylicresin (Triad; Dentsply Sirona). Make a hole on theTS at the edentulous area.18

3. Use an oversized osteotomy drill to simulate theosteotomy of implant placement on the stone cast(Fig. 2). Evaluate the simulated oversized osteot-omy (SOO) on the diagnostic stone cast. A vac-uum shell based on the diagnostic wax patterncan be used as a guide but is not necessary at thisstage because the goal is to create a SOO thatwould accommodate the implant analog on theday of surgery; high precision, therefore, is notneeded.

4. Reflect full-thickness labial and lingual flaps and,with the patient under local anesthesia, place thedental implant with the aid of a surgical stent andcopious saline irrigation (Fig. 3A). Place an opentray impression coping on the implant and positionthe TS intraorally. The impression coping shouldbe located in the hole prepared in the laboratory.Ensure there is no contact between the impressioncoping and the TS.

5. Place autopolymerizing acrylic resin around theimpression coping and the TS (Fig. 3B). Removeany excess autopolymerizing acrylic resin mate-rial that would interfere with the occlusal screwaccess of the impression coping. Allow propertime for the polymerization to occur; remove theTS with the attached impression coping andattach an implant analog to the impressioncoping.

6. Mix autopolymerizing acrylic resin and place it inthe SOO (Fig. 4A). Create a small vent hole aroundthe vestibular area of the SOO to allow the venting

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of any excess acrylic resin material. Place the TS onthe diagnostic stone cast and allow the acrylic resinto adequately polymerize (Fig. 4B). After poly-merization, remove the TS; implant positioninghas been replicated on the diagnostic stone cast.Then attach a scanning abutment and scan thestone cast (D700; 3Shape).

7. Design the contours, esthetics, and emergenceprofile of the interim screw-retained restoration(ISRR) by using the software that accompanies thespecific scanner (Fig. 5A). The software providesinternal space in the interim prosthesis in whichthe titanium prefabricated insert can be attached.Confirm the design, and mill the ISRR from ablank of prepolymerized PMMA, using a millingmachine (TS150 Milling Solution; IOS Technolo-gies).20 Attach a titanium insert to the interimprosthesis with resin cement (Panavia F2.0; Kur-aray America, Inc) (Fig. 5B). Evaluate the contours,emergence profile, and interproximal contacts onthe stone cast.

8. Insert the ISRR, and suture the flaps (Fig. 5C).Ensure that the interim crown is slightly ininfraocclusion. Confirm occlusal clearance atapproximately 40 mm with 4 layers of 10-mm shimstock (Occlusal registration strips; Patterson DentalSupply, Inc). Evaluate the proximal contacts with asingle layer of shim stock before sealing theocclusal access hole. Allow proper time forosseointegration to occur.

9. While the implant is allowed to osseointegrate,design a customized impression coping by usingthe same software and follow the gingival contours

Proussaefs and AlHelal

Figure 3. A, Surgical placement of dental implant completed. B, Transfer stent placed intraorally, and open tray impression copingfixed on implant. Autopolymerizing acrylic resin used to connect impression coping to transfer stent.

Figure 4. A, Autopolymerizing acrylic resin inserted into oversized hole created on diagnostic stone cast. Small hole created on facial aspect toallow extrusion of excess acrylic resin material. B, Transfer stent and impression coping fixed on diagnostic stone cast.

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of the ISRR (Fig. 6). Mill the custom titaniumimpression coping (CTIC) from a titanium blank byusing a milling machine.

9. After osseointegration has been conformed,remove the ISRR and evaluate the tissue profile(Fig. 7A). Insert the CTIC and make the definitiveimpression with PVS impression material (Fig. 7B).

10. Design the definitive prosthesis to have identicalgingival contours as the ISRR (Fig. 8A). A screw-retained CAD-CAM milled zirconia crown with ametal insert was fabricated in the described clinicalsituation.21,22

11. Insert the definitive prosthesis (Fig. 8B). Confirmesthetics, occlusion, and interproximal contacts.The gingival contours of the definitive prosthesisshould be identical with the gingival contours ofthe ISRR and CTIC. Place a cotton pellet and

oussaefs and AlHelal

composite resin (Filtek Supreme Ultra; 3M ESPE)to seal the occlusal access hole.

DISCUSSION

The objective of the proposed technique is to offer animmediate interim restoration and obtain peri-implantsoft tissue contours similar to those of the definitiveprosthesis. The gingival contours of the ISRR can be usedas a reference by the corresponding software to produce aCTIC and definitive prosthesis with identical gingivalcontours.

The use of a TS during implant surgery has beendescribed18 as a method of transferring implant positionin the laboratory and fabricating an ISRR indirectly.With the described technique, the ISRR is milled from aPMMA blank, which has better mechanical properties

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Figure 5. A, Screw retained interim prosthesis digitally designed,occlusal view. B, Interim prosthesis milled from polymethylmethacrylateblock and titanium insert fixed. C, Intraoral view, interimprosthesis.

Figure 6. Milled titanium impression coping digitally designedwith gingival contours identical those of interim prosthesis.

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than autopolymerized acrylic resin because of poly-merization shrinkage before the milling process, isinitiated.20

The conventional protocol for fabricating an ISRRafter implant surgery involves the use a prefabricatedinterim abutment and a clear vacuum shell fabricated

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based on a diagnostic waxing.11,12 However, the auto-polymerizing acrylic resin may lack the mechanicalproperties to withstand pressure applied from the sur-rounding tissue that tends to relapse. In addition, effec-tively isolating blood and saliva from the operating areamay be challenging. Therefore, the metal acrylic interfacemay be easily contaminated. With the described tech-nique, the fabrication of the ISRR is made extraorally,avoiding saliva or blood contamination or surroundingtissue collapse.

In the described technique, a CTIC was used totransfer soft tissue anatomy. The described CTIC wasdesigned with contours identical with those of the ISRRand the definitive prosthesis. Custom impressioncoping milled from a PMMA block has beendescribed6,7; however, a customized impression copingmilled from titanium may be preferable because of thematerial’s rigidity and stability as compared withPMMA.

Alternatively, a digital scan can be made to replicatethe soft tissue profile after healing has been completed.16

However, Joda17 reported 21.7% shrinkage of the peri-implant soft tissue within 10 minutes of removing theinterim restoration. The degree of soft tissue shrinkagebefore digital intraoral impression can be completed isunknown.

The main disadvantage of the proposed technique isthe additional cost involved with designing and fabri-cating the ISRR. The proposed technique assumes thatthe clinician has access to a milling machine the day ofimplant surgery. Alternatively, the ISRR can be placedthe next day after implant surgery. The reduced chairtime and the feasibility of obtaining and replicating softtissue contours similar those of the definitive prosthesismay justify the additional cost.

Proussaefs and AlHelal

Figure 7. A, Tissue contours 4 months after surgery and placement of immediate restoration. B, Milled titanium impression coping, intraoral view.

Figure 8. A, Definitive restoration, zirconia screw-retentive crown with titanium insert designed with contours identical those of interim prosthesisand milled custom titanium impression coping. B, Intraoral view, definitive prosthesis 6 months after insertion.

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SUMMARY

The described technique offers an alternative method ofobtaining soft tissue contours similar to those of thedefinitive prosthesis by using a milled titanium healingabutment. The obtained contours are transferred to thelaboratory with a custom milled titanium impressioncoping. A clinical study is needed to validate the use ofthe described technique.

REFERENCES

1. Moscovitch MS, Saba S. The use of a provisional restoration in implantdentistry: A clinical report. Int J Oral Maxillofac Implants 1996;11:395-9.

2. Daftary F, Bahat O. Prosthetically formulated natural esthetics in implantprostheses. Pract Periodontics Aesthet Dent 1994;6:75-83.

3. Lewis S. Anterior single-tooth implant restorations. Int J PeriodonticsRestorative Dent 1995;15:31-41.

4. Neale D, Chee WW. Development of implant soft tissue emergence profile: atechnique. J Prosthet Dent 1994;71:364-8.

5. Biggs WF. Placement of a custom implant provisional restoration at thesecond-stage surgery for improved gingival management: a clinical report.J Prosthet Dent 1996;75:231-3.

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6. Proussaefs P. A Novel technique for immediate loading single root formimplants with an interim CAD/CAM milled screw-retained crown. J OralImplantol 2016;42:327-32.

7. Proussaefs P. Immediate provisionalization with a CAD/CAM interim abut-ment and crown: a guided soft tissue healing technique. J Prosthet Dent2015;113:91-5.

8. Proussaefs P, Lozada J. Immediate loading of hydroxyapatite-coated implantsin the maxillary premolar area: three-year results of a pilot study. J ProsthetDent 2004;91:228-33.

9. Atieh MA, Atieh AH, Payne AG, Duncan WJ. Immediate loading with singleimplant crowns: a systematic review and meta-analysis. Int J Prosthodont2009;22:378-87.

10. Yan Q, Xiao LQ, Su MY, Mei Y, Shi B. Soft and hard tissue changes followingimmediate placement or immediate restoration of single-tooth implants inthe esthetic zone: a systematic review and meta-analysis. Int J Oral MaxillofacImplants 2016;31:1327-40.

11. Oyama K, Kan JY, Rungcharassaeng K, Lozada J. Immediate provisionali-zation of a 3.0-mm-diameter implants replacing single missing maxillary andmandibular incisors: 1-year prospective study. Int J Oral Maxillofac Implants2012;27:173-80.

12. Kan JY, Rungcharassaeng K, Lozada J. Immediate placement and provi-sionalization of maxillary anterior single implants: 1-year prospective study.Int J Oral Maxillofac Implants 2003;18:31-9.

13. Lin WS, Harris BT, Morton D. Use of implant-supported interim restorationsto transfer periimplant soft tissue profiles to a milled polyurethane definitivecast. J Prosthet Dent 2013;109:333-7.

14. Noh K, Kwon KR, Kim HS, Kim DS, Pae A. Accurate transfer of soft tissuemorphology with interim prosthesis to definitive cast. J Prosthet Dent2014;111:159-62.

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15. Man Y, Qu Y, Dam HG, Gong P. An alternative technique for the accuratetransfer of periimplant soft tissue contour. J Prosthet Dent 2013;109:135-7.

16. Monaco C, Evangelisti E, Scotti R, Mignani G, Zucchelli G. A fully digitalapproach to replicate peri-implant soft tissue contours and emergence profilein the esthetic zone. Clin Oral Implants Res 2016;27:1511-4.

17. Joda T. Time-dependent supraimplant mucosa changes: short communica-tion. Int J Oral Maxillofac Implants 2015;30:619-21.

18. Proussaefs P, Lozada J. Immediate loading of single root form implants withthe use of a custom acrylic stent. J Prosthet Dent 2001;85:382-5.

19. Priest G. Virtual-designed and computer-milled implant abutments. J OralMaxillofac Surg 2005;63:22-32.

20. AlHelal A, AlRumaih HS, Kattadiyil MT, Baba NZ, Goodacre CJ. Comparisonof retention between maxillary milled and conventional denture bases: aclinical study. J Prosthet Dent 2017;117:233-8.

21. GehrkeP,Alius J, FischerC,ErdeltKJ,BeuerF.Retentivestrengthof two-pieceCAD/CAM zirconia implant abutments. Clin Implant Dent Relat Res 2014;16:920-5.

Noteworthy Abstracts of

A comparative analysis on two types of oralwith different cantilever lengths of fixed pros

Mosavar A, Nili M, Hashemi SR, Kadkhodaei MJ Prosthodont 2017;26:289-295

Purpose. Depending on esthetic, anatomical, and functionaledentulous jaw, the selection of implant type is highly impotheir stress distribution in bone have not yet been comparatused to study the influence of cantilever length in a fixed praround these two types of oral implants.

Material and Methods. A 3D edentulous mandible was mocantilever lengths and two types of implants, bone-level andapplied to the distal regions of the cantilevers, and the von-independent t-test and the Pearson correlation coefficient an

Results. Stresses in the cortical bone around the bone-levelimplants with the same cantilever length. In addition, by extimplant bone increased. Therefore, when the cantilever was abone and around the bone-level distal implants.

Conclusions. The results of the present study indicate thatadvantageous than with bone-level implants for implant-sup

Reprinted with permission of The American College of Pros

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22. Chun HJ, Yeo IS, Lee JH, Kim SK, Heo SJ, Koak JY, Han JS, Lee SJ.Fracture strength study of internally connected zirconia abutments rein-forced with titanium inserts. Int J Oral Maxillofac Implants 2015;30:346-50.

Corresponding author:Dr Periklis ProussaefsAdvanced Education Program in Implant DentistryDepartment of Restorative DentistryLoma Linda University3585 Telegraph Rd, Suite CVentura, CA 93003Email: DrProussaefs@gmail.com

Copyright © 2017 by the Editorial Council for The Journal of Prosthetic Dentistry.

the Current Literature

implants, bone-level and tissue-level,thesis

aspects, in implant-prosthetic restoration of a completelyrtant; however, bone- and tissue-level implants andively investigated. Hence, finite element analysis wasosthesis on stress distribution in peri-implant bone

deled. In simulations, a framework with four posteriortissue-level, was considered. A compressive load was

Mises stress of peri-implant bone was investigated. Thealyzed the results (a=0.05).

implants were greater than those in the tissue-levelending the cantilever length, the stress values in peri-t its maximum length, the maximum stress was in cortical

treatment with tissue-level implants is potentially moreported fixed prostheses.

thodontists.

Proussaefs and AlHelal