The Use of Dental Implants in Combination withRemovable Partial Dentures. A Case Report

VASSILIOS CHRONOPOULOS, DDS, Msc, PhD*

ASPASIA SARAFIANOU, DDS, Dr.Odont†

STEFANOS KOURTIS, DDS, Dr.Odont‡

ABSTRACTImplant treatment protocols for fully edentulous patients include implant-supported fixed resto-rations with a minimum of five to six implants or overdentures on two to four implants.However, implant placement in the posterior areas is sometimes not permitted by anatomicand/or financial restraints, or patients’ unwillingness to have extensive surgical procedures.

The purpose of this case report is to present a treatment option where bilateral distal extensionremovable partial dentures (RPDs) are used in combination with anterior fixed implantprostheses with semi-precision attachments.

The initial treatment plan of a 65-year-old female with failing dentition involved the fabricationof overdentures supported by four implants placed in the interforaminal area in both arches.Because of inadequate space for the retentive elements of the overdenture and the patient’sobjection to surgical procedures for the placement of additional implants to support a fixedrestoration, the treatment plan was modified. Fixed ceramometal cement-retained implant res-torations with semi-precision attachments adjacent to the distal abutments were fabricated inthe maxilla and the mandible. Bilateral distal extension RPDs were placed in both arches. Thepatient’s benefits were increased comfort, good esthetics in the anterior area, improved phonet-ics, and masticatory function. Retentive element maintenance requirements were similar to con-ventional RPDs. More extended controlled clinical studies are needed to establish the long-termsuccess of this treatment option.

CLINICAL SIGNIFICANCERemovable partial dentures may offer an attractive treatment option for an edentulous patient,as they may combine an FPD in the anterior segment with a removable appliance in the poste-rior areas. A satisfying restoration can be achieved with fewer implants.

(J Esthet Restor Dent 20: 355–365, 2008)

*Lecturer, Department of Prosthodontics, Dental School,National and Kapodestrian University of Athens, Athens, Greece

†Clinical Instructor, Department of Prosthodontics, Dental School,National and Kapodestrian University of Athens, Athens, Greece

‡Assistant Professor, Department of Prosthodontics, Dental School,National and Kapodestrian University of Athens, Athens, Greece

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I N T R O D U C T I O N

The restoration of completelyedentulous patients with

implants represents a major chal-lenge for the clinician. The stan-dard clinical protocols includefixed restorations with a minimumof five to six implants or remov-able overdentures with two tofour implants.1,2

In some cases, however, the treat-ment plan has to be adapted to thepatient’s demands.

Certain patients demand a fixedrestoration in the anterior area,although willing to accept aremovable prosthesis for the poste-rior region. The insertion ofimplants in the posterior areasoften requires extensive surgicalprocedures because of excessivebone loss.3–5 In addition, the needfor more implants increases thetotal treatment cost.

Patients who have been using aremovable partial denture (RPD)are accustomed to removableappliances but may be unwilling toconvert to an implant supportedoverdenture if anterior teeth arelost. Their major demand is arestoration resembling thepreexisting one.

The use of RPDs in conjunctionwith implants has been previouslyreported.6–8 However, there are

very few studies on the use ofRPDs connected to fixed implant-supported restorations.7,8

P U R P O S E

The purpose of the this case reportis to present a case where bilateraldistal extension RPDs were used incombination with anterior fixedimplant prostheses withsemi-precision attachments.

C A S E P R E S E N TAT I O N

A 65-year-old Caucasian femalepatient presented for treatment.The initial clinical and radiologi-cal examination revealed that thepatient suffered from severeperiodontitis. All maxillary andmandibular teeth showed poorprognosis and were consideredhopeless (Figure 1). The treatmentplans presented to the patientincluded fixed implant supportedrestorations for both arches,implant supported overdentures,and conventional complete den-tures. The patient preferred afixed restoration but could notafford a great number ofimplants. Additionally, she didnot consent to extensive surgicalprocedures for implant placementin the posterior areas (i.e., boneaugmentation, sinus lift). Thetreatment plan that was decidedupon included implant-retained,bar-supported overdentureson four implants ineach arch.

Four maxillary (16, 13, 23, 26)and three mandibular (38, 33, 43)teeth were maintained until thesecond stage surgery to supportprovisional fixed restorations(Figures 2 and 3). The remainingteeth were selected according totheir distribution in the dental archand their position in relation toprospective implant placementsites. The patient followed a peri-odontal recall program to ensureinflammation control during thehealing period (5 months).

Four implants (Osseotite ExternalHex; 3i Biomet Co., Palm Beach,FL, USA) were placed in themaxilla in the areas of the lateralincisors and first premolars (#14,12, 22, 24). In the mandible, foursimilar implants were inserted inthe equivalent areas (#34, 32, 44,42). The implant in the area of theleft lateral mandibular incisor(#32) failed during osseointegra-tion, but the patient refused a newsurgery to replace it.

After second stage surgery a set ofimmediate complete dentures werefabricated to serve as interimrestorations and as a guide forthe final restorations. Additionalsupport and retention wereachieved using healing screws (EPHealing Screws; 3i Biomet Co.)with increased height over theimplants. Vertical dimension, softtissue support, esthetics, and pho-netics were evaluated and adjusted

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during the fabrication of theinterim dentures.

The final impressions were madeusing the open-tray technique(Figures 4 and 5). The finalworking casts were fabricatedusing ISO Type-4 dental stone(Silky-Rock; WhipMix Co., Louis-ville, KY, USA) with a soft tissuereplica (Gingiva Mask; GC Co.,Tokyo, Japan). Screw-retained

baseplates were used for the regis-tration of centric relation. Theset-up from denture teeth wascompleted using the interim resto-rations as a guide (Figures 6 and7). The set-up was tried clinicallyfor verification of esthetics, occlu-sion, and phonetics (Figure 8). Thecasts were mounted to a semi-adjustable articulator (Hanau WideView; Teledyne Hanau, Buffalo,NY, USA) (Figure 9).

Silicon indexes were obtained fromeach set-up to allow space evalua-tion for the supporting bar andmetal framework (Figures 10 and11). Because of the labial inclina-tion of the implants, the spaceavailable in both arches wasminimal. This could lead to seriousmaintenance problems, such asfrequent replacement of retentiveelements or acrylic teeth and/orbase fractures, causing patient

Figure 1. Initial panoramic X-ray. Figure 2. Panoramic X-ray after preparation of theabutment teeth for the provisional restorations and priorto implantation.

Figure 3. The provisional restorations. Figure 4. Impression copings for open-tray technique onfour maxillary implants.

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complaints and increased cost.Moreover, the patient was stronglyconcerned with the appearance ofthe metal bar when removing theoverdentures for oral hygiene pur-poses. Because of these problems,an alternative treatment plan wasproposed, including the fabricationof a fixed implant-supported fixedpartial denture (FPD) in botharches, with semi-precision attach-ments retaining a bilateral distal

extension RPD. The patient con-sented to the increase in the overallcost because of the anteriorfixed restorations.

For the fabrication of the cement-retained restorations, two prefabri-cated titanium (Prep Tite Post; 3iBiomet Co.) and two custom-madeabutments were used in the maxilla(Figure 12). In the mandible, twoprefabricated titanium and one

custom-made abutment were used(Figure 13). The custom-madeabutments were fabricated by over-casting UCLA abutment cylinders(Gold Standard ZR hexed; 3iBiomet Co.) using a high goldalloy (V-Delta Metalor Co.,Neuchatel, Switzerland). Both pre-fabricated and cast abutments wereindividualized using the siliconindex from the set-up. Fixedceramometal cemented implant

Figure 5. Impression copings for open-tray technique onthree mandibular implants.

Figure 6. Diagnostic set-up for maxillary intermediatecomplete dentures on screw-retained base plates.

Figure 7. Diagnostic set-up for mandibular intermediatecomplete dentures on screw-retained base plates.

Figure 8. Try-in of the teeth set-up.

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restorations with semi-precisionattachments (ERA; Sterngold Co.,MA, Attleboro, USA) adjacentto the distal abutments werefabricated (Figures 14 and 15).

The metal frameworks were triedclinically to verify passive fit(Figure 16). Veneering of theimplant-supported FPDs wascarried out in the conventional

way (Figures 17 and 18). Gingiva-colored porcelain was added at thecervical areas to compensate forthe preexisting bone resorption.

The framework design for theRPDs followed the classical prin-ciples. Indirect retention for theframework was achieved throughlingual cingulum rests. The sub-stantial bone loss caused by the

removal of the teeth, resulted inlimited space available for a lingualbar-type major connector. A modi-fied lingual bar was designed atthe height of the cingulum rests(Figures 19 and 20).

The patient was satisfied with thefinal result and the clinical condi-tion remained stable at the 1-yearrecall (Figures 21 and 22).

Figure 9. Unfavorable maxillary and mandibular implantinclination.

Figure 10. Evaluation of the available space in the maxillausing silicone index from the set-up.

Figure 11. Evaluation of the available space in themandible using silicone index from the set-up.

Figure 12. Individualized prefabricated and custom-madeabutments before overcasting in the maxillary cast.

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D I S C U S S I O N

The use of dental implants withoverdentures has been extensivelydocumented in the literature.9–11

Dental implants as retentive and/orsupportive elements of RPDshave been reported.6–8 Extensiveclinical studies concerning theirclinical use have been

sporadically published. Accordingto a literature review6 thereare a few case reports and oneshort-term and one longitudinalclinical study.

Mitrani and colleagues published aretrospective study of 10 partiallyedentulous patients unsatisfied

with their RPDs (Kennedy Class Iand II). Posterior osseointegratedimplants were placed, providingstability and/or retention of theremovable prostheses and eliminat-ing the need for clasps when pos-sible. The authors reported patientsatisfaction, minimal componentwear, stable tissue condition, and

Figure 13. Individualized prefabricated and custom-madeabutments before overcasting in the mandibular cast.

Figure 14. Metal framework for fixed, implant-supported,cement-retained restorations with ERA attachments in themaxilla.

Figure 15. Metal framework for fixed, implant-supported,cement-retained restorations with ERAattachments in the mandible.

Figure 16. Metal framework try-in.

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Figure 17. Maxillary anterior restorations after veneering. Figure 18. Mandibular anterior restorations afterveneering.

Figure 19. Maxillary restorations. Figure 20. Mandibular restorations. Note the majorconnector modification.

Figure 21. Final clinical result. Figure 22. Panoramic X-ray of final fixed implant-supported restorations at 1-year recall.

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no radiographic evidence of boneloss with a follow-up of 1 to4 years.12

Mijiritsky and colleagues publisheda longitudinal study investigatingthe use of implants in conjunctionwith teeth-supported RPDs. Fifteenpatients were treated with afollow-up of 2 to 7 years. Thisclinical approach was considereda viable and cost-effective treatmentmodality, leading to improvedchewing efficiency with onlyminor prosthetic complications.13

In numerous case reports14–19 oneor two implants were placed in themolar areas to contribute to thesupport and/or retention of distalextension RPDs. Jang and col-leagues20 reported the use of animplant metal-ceramic crownas an RPD abutment. Multipleimplants have been usedby various authors forRPD retention.21–23

Implants connected to natural teethhave been used as RPD abutmentsin some clinical reports.24–28 In themajority of the studies mentionedearlier, the complexity of designand the connection of implants tonatural teeth increased the overalldifficulty of the treatment.Additionally, treatment time andcost were significantly increased.Anterior fixed implant-supportedrestorations connected to posteriordistal extension RPDs have been

reported by Starr7 and Pellechiaand colleagues.8

In the treatment option proposedin the present article, the classicprinciples of fixed–removable pros-theses were followed, leading to asimplified clinical and laboratoryprocedure. The patient’s benefitswere increased comfort, superioresthetics in the anterior area,improved phonetics, and mastica-tory function. Patient satisfactionwas further enhanced by the factthat the anterior teeth did not needto be removed either for oralhygiene or during sleep. Normalemergence profiles, phonetics, lipsupport, and anterior guidancewere established with the implant-supported FPD. Vertical dimensionwas successfully restored with theincorporation of first premolarsin the FPDs.

The patient was completely satis-fied with the treatment result. Theneed for the replacement of theretaining components of the preci-sion attachments was similar toconventional RPDs. Patient self-confidence was increased bythe use of an anterior fixedrestoration instead of anunesthetic bar.

The non-axial loading of thedistal implants by the precisionattachments may be considereda mechanical risk factor.28 Thiswas minimized by the proper

design of the RPD, according tothe classic prosthodontic prin-ciples. Pellechia and colleagues8

observed normal bone levelsaround implants supporting RPDsafter a period of 3 years and con-cluded that stress-breakers prob-ably reduced the masticatory loadon the supporting implants. Addi-tionally, the use of cantilevers inimplant restorations is a commonand documented clinical proce-dure, with satisfactory long-termresults.28 The role of implantlength and diameter associatedwith distal extension RPDs canstill be considered under investiga-tion.29 Bars supporting overden-tures provide splinting of theimplants, but vertical andhorizontal space required fortheir use is not alwaysavailable, as shown in thepresented case.

Alternative treatment plans in thepresented case would be implant-supported overdentures and fixedrestorations with cantilevers.Implant overdentures are notalways well accepted by patients,whereas prosthetic complications(i.e., acrylic teeth and/or base frac-tures) and maintenance require-ments (i.e., replacement ofretentive elements, rebasing, orrelining) may increase chair-timeand cost.30,31 Additionally,the patients have to accept thepresence of a metal bar or ballattachment when the overdenture

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is removed. This option is rejectedby a number of patients. Therestoration of the patient presentedin this case with cantilever prosthe-sis would limit the distal extensionto the second premolar. This wouldlead to a shortened dental archwith reduced chewing perfor-mance32 and possibly estheticproblems caused by the lack ofposterior buccal support. In everycase the patient’s demands haveto be carefully evaluated duringtreatment planning.

From the surgical and prostheticstandpoint, an ideal treatment planwould include bone augmentationin both arches and placement ofsix to eight implants in the maxillaand six implants in the mandibleto support a fixed implant restora-tion. The final decision wasreached after evaluation of thetime and cost involved, thedemands of the patient,and her objection to multiplesurgical procedures.

Within the limitations of thepresent case report (lack of long-term clinical results), the useof implant-supported fixedrestorations in combination withRPDs may be proposed as aneffective and viable clinical solu-tion in selected cases. Extensiveclinical longitudinal studies areneeded to establish thelong-term success of thistreatment modality.

D I S C L O S U R E A N D

A C K N O W L E D G M E N T S

The authors do not have anyfinancial interest in the companiesmanufacturing the materialsincluded in this article.

The authors wish to thank Mr.Demetrios Carvelas, CDT forthe technical construction of thepresented restoration.

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Reprint requests: Stefanos Kourtis, DDS,Dr. Odont, Plaza Chrys. Smyrnis 14, 17121Athens, Greece; Tel.: 30-697-2838900; Fax:30-210-9357306; email: stefkour@dent.uoa.gr

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