Met

man

atta

Edgar Grageda,

aAssociate Professor, Department ofand Private practice, Mexico City, MbOwner, Dental Technik Laboratory.

The Journal of Prosthetic

al-reinforced single implant

dibular overdenture retained by an

chment: A clinical report

DDS, MSa and Bastian Rieck, DTb

National Autonomous University of Mexico UNAM; Medica SurHospital, Mexico City, Mexico

Results of studies have shown that a single implant mandibular overdenture significantly increases the satisfaction and qualityof life of patients with edentulism. The single implant-retained overdenture has the additional advantage of being lessexpensive and invasive than a 2-implant supported overdenture but has a high incidence of fracture of the acrylic resin base atthe point of the implant. The treatment, design, and fabrication of a metal-reinforced single-implant mandibular overdenturewith the Locator attachment as a retention device is described. (J Prosthet Dent 2014;111:16-19)

1 Frontal view of existing denture and remaining mandibularteeth.

Edentulism correlates highly withlow-income, poor health, and reducededucation.1-4 For more than a century,complete dentures were the standard ofcare for the patient with edentulism.Implant-retained or implant-supportedprostheses have been shown to bemore efficient than a complete denture,based on measures of quality of life,satisfaction, the ability to masticate,the ability to speak, and the nutritionalstate of the patient.5-9 The use of either2 or 4 implants for mandibular den-ture anchorage, either free standing orconnected by a bar, is the treatmentabout which most is known.10-19 Re-cently, the use of a symphyseal singleimplant for mandibular overdentureanchorage has been used as a treat-ment alternative and has been shownto be equally effective and less expen-sive than the 2-implant mandibularoverdenture.20-24 The standard ball at-tachment and the Locator attachment(Zest Anchors) are the 2 retentive de-vices that have been studied with the1-implant mandibular overdenture, andboth have positive outcomes.25 A dis-advantage of the 1-implant mandibularoverdenture is the incidence of fracture,which is reported to be high for over-dentures retained by either 1 or 2 im-plants.26 If a fracture occurs, then it

Prosthodexico.

Dentis

tends to be in areas where the acryl-ic resin is the thinnest, that is, adja-cent to the implant. This disadvantage

2 Panoramic radiograph.

ontics, National Autonomous University of Me

try

can be addressed by adding a metal-reinforcing framework inside the acrylicresin base.

xico UNAM and Medica Sur Hospital;

Grageda and Rieck

3 Symphyseal implant tightened to 35 Ncm.

4 Panoramic radiograph 6 weeks after surgery, showingmandibular implant in place.

5 Locator attachment tightened to 35 Ncm.

January 2014 17

CLINICAL REPORT

A 76-year-old woman presented tothe Medica Sur Hospital, EG dentalclinic with a poorly fitting maxillarydenture and mobility of the remainingmandibular teeth (Fig. 1). Her medicalhistory was not relevant to the proposeddental treatment. A clinical examinationrevealed a maxilla with ischemic tissueon the palatal site and erythematoustissue on the border of the ridge dueto continuous wearing of the dentalprosthesis. The mandible presented ad-equate posterior alveolar ridges withattached mucosa. Severe periodontitisof the remaining mandibular teeth wasnoted, and the radiographic examina-tion revealed thin, finely trabeculatedbone that separated the oral cavity fromthe nasal cavity, with extensively pneu-matized sinuses. No evidence of intrinsicpathology was noted, with the excep-tion of the severe periodontitis of theremaining mandibular teeth (Fig. 2).Among the treatment alternatives thatwere explained to the patient were con-ventional complete dentures, implantoverdentures, and implant-fixed com-plete dentures with varying numbers ofimplants. Based on the patient’s ex-pectation, cost consideration, and di-agnostic information, the treatmentchosen was multiple extractions of themandibular teeth with simultaneousimplant placement and fabricationof a metal-reinforced single-implantmandibular overdenture retained by aLocator attachment.

At the surgical appointment, thepatient was asked to complete a 30-second preoperative oral chlorhexidine0.12% rinse (Perioxidin; Ladec). Bilat-eral mandibular block local anesthesiawas administered (4 mL Articaine withepinephrine 1/100 000 Medicaine Sep-todont), and the remaining mandibularteeth were atraumatically removed. Af-ter the extractions, a crestal gingivalincision was made, which extended 10mm distally onto the remaining alveolarprocess, and a full-thickness muco-periosteal flap was reflected, which ex-posed uneven mandible bone excess.The mandibular midline was exposed,

Grageda and Rieck

and the alveolar ridge was leveled byusing a round bur to create a flat bonebase with sufficient restorative space.One root form implant (NT Osseotite4�13 mm; Biomet 3i) was inserted intothe mandibular symphysis and orientedperpendicular to the occlusal plane(Fig. 3). The implant was placed with

an insertion torque of 35 Ncm. A heal-ing abutment was connected, and themucosa was sutured with 3-0 contin-uous silk suture (Ethicon; Johnson &Johnson). Postoperative care instruc-tions and medications were prescribed(amoxicillin and clavulinic acid 500mg per 12 hours for 7 days and

6 Wax pattern of metal-reinforced framework.

7 Overdenture base with metal-reinforced framework.

8 Definitive prosthesis in place.

18 Volume 111 Issue 1

ketarolac 30 mg per 12 hours for 3days). The surgical site was evaluated,and the sutures were removed after 2weeks of healing.

The implant was allowed to heal forapproximately 6 weeks, at which timea radiograph was made (Fig. 4). TheLocator abutment was then connectedto the patient implant at 35 Ncm(Fig. 5) and preliminary impressionswere made with irreversible hydrocolloid(xantAlgin; Heraeus Kulzer). Customimpression trays were fabricated (Pala-tray XL; Heraeus Kulzer).

At the definitive impression ap-pointment, the custom impression trayswere border molded with modelingplastic impression compound (Impres-sion compound type I; Kerr Corp). Theimpression was made with polysulfideimpression material (Permlastic Regu-lar; Kerr Corp). The Locator impressioncap was used as a direct impressioncoping, and the implant Locator analogwas placed in the definitive impression.The impression was immediately boxedand poured in Type III dental stone(Micro Stone; Whip Mix Corp) Resinrecord bases and wax occlusal rimswere fabricated to average dimensions.An arbitrary facebow and vertical andcentric relation interocclusal recordswere made. The definitive casts werearticulated on a semiadjustable articu-lator (8500 series; Whip Mix Corp). Thetooth arrangement incorporated bothan anterior-posterior and mediolateralcompensating curve to achieve bilateralbalance occlusion.

The trial dentures were clinicallyassessed, and the accuracy of the artic-ulated casts and condylar inclinationsettings were verified. The patient ac-cepted the esthetics. The position ofthe mandibular teeth was recorded bymaking a facial polyvinyl siloxane matrix(Speedex Putty; Coltène/Whaledent).The mandibular trial denture was re-moved from the master cast, and themetal housing portion of the Locatorabutment was connected. The designof the metal reinforced framework wasdrawn on the definitive cast. A waxblock out was performed on the alveolarridge and around the Locator

The Journal of Prosthetic Dentis

attachment area for the production of arefractory cast. Preformed plastic pat-terns for partial removable dental pros-theses were placed onto the investmentcast to create the desired contoursfor a custom-made metal reinforcing

try

framework (Fig. 6). The wax pattern wassprued, invested, and cast with a basealloy with traditional methods (Vital-lium Alloy Co60 Cr31 Mo6; Dentsply).The metal framework was finished andplaced onto the definitive cast. A facial

Grageda and Rieck

January 2014 19

silicone matrix was used to facilitateaccurate repositioning of the mandib-ular denture teeth.

After refining the denture contours,the wax pattern was invested, packed,and processed in heat polymerized poly(methyl methacrylate) (Meliodent HeatCure; Heraeus Kulzer) denture baseresin with conventional techniques. Theprocessed dentures were returned tothe articulator for occlusal equilibra-tion. The dentures were removed fromthe casts, finished, and polished. Theblack plastic nylon processing insert ofthe locator attachment was removedand the pink plastic nylon insert wasinserted into the matrix housing withthe appropiate tool (Fig. 7). After aclinical remount and occlusal equili-bration (Fig. 8), clinical fit assessmentand adjustment were accomplishedwith pressure-indicating paste (MizzyInc). Immediate posttreatment therapyincluded 24-hour, 1-week, and 3-weekevaluations, each involving the evalua-tion of occlusion, oral hygiene, andpatient satisfaction and comfort. Noclinical complication was seen, and thepatient has been followed-up every 6months for 2 years.

SUMMARY

The single implant mandibular over-denture can be an economical, func-tional, and esthetic treatment option.The use of a metal-reinforced frame-work inside the acrylic resin base pro-vides better rigidity to prevent denturefracture; furthermore, the use of a Lo-cator attachment seems to be a suitableattachment system.

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Corresponding author:Dr Edgar GragedaMedica Sur HospitalPuente de Piedra 150Torre I Int 905-913, Mexico CityMEXICOE-mail: edgargrageda@hotmail.com

Copyright ª 2014 by the Editorial Council forThe Journal of Prosthetic Dentistry.