Fabrication of a maxillary prosthesis using dental implants and an “overdenture” attachment. A clinical report Paul J. Mentag, D.D.S.,* Lawrence L. Sowinski***

Timothy

F. Kosinski,

M.S., D.D.S.,**

and

University of Detroit, School of Dentistry, Detroit, Mich.

A

.%-year-old woman with controlled hypothyroidism and mild arthritis began treatment in 1971. The patient’s maxillary teeth and several mandibular teeth were lost asa result of periodontitis. A blade implant was placed in the mandibular right quadrant at that time. The region is still healthy and providing excellent support. The patient’s major concern was an inability to function properly with her conventional maxillary complete denture becauseof a chronic gaggingreflex. She retained the denture with adhesive for many years. Intramucosal inserts were placed to eliminate the useof denture adhesivesand minimize the patient’s severe gag reflex by improving maxillary denture stabilizati0n.l The inserts allowed fo:r removal of someof the acrylic resin on the palate, which reduced the gagreflex. The denture was well retained for 3 years, after which the underlying mucosaltissuesbecamehypertrophied, inflamed, and irritated, resulting in the removal of the intramucosal inserts. The tissueswere conditioned by useof a seriesof soft lining materials after minimal surgical revision. With the advent of the intramobile cylinder implants (IMZ), (Interpore International, Irvine, Calif.), osteointegrated dental implant system, a new maxillary prosthesis using dental implants was planned. Preoperative panoramic and intraoral radiographs indicated sufficient vertical bone height and proper bone pattern to accept endosseousimplants (Fig. 1). To achieve stablility of the maxillary prosthesisover the IMZ dental implants, many different concepts were considered, including magnets,O-ring attachments, Ceka attachments, and the Stern ERA (APM Sterngold, Atteboro, Mass.) attachment. The ERA “overdenture” attachment was selectedbecauseof its resilient properties.

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The ERA concept is a retention systemthat offers two designvariations, (1) the extracoronal (or partial denture)

*Clinical Professor, Department of Prosthodontics. **Clinical Assistant Professor, Department of Stomatology, Oral Medicine Section. ***Certified Dental Technician, Somer Dental Ceramics, Zionsville, Ind.

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attachment for placement on the distal or mesialaspect of natural abutments or implants and (2) the axial (or overdenture) attachment, typically for placement on occlusal surfacesof nonvital roots or implants. The ERA overdenture attachment allowsfor placementof additional support within the bar framework, thus providing increasedretention. Each ERA retention system is available in a variety of resistancesidentified by color coding. The nylon attachment portion virtually eliminates wear of the receptacle. Each attachment includes four color-coded synthetic attachmentsthat provide different degreesof retention from light to heavy and are correspondingly color-coded white, orange, blue, and gray.2 A black fabricating attachment that automatically provides for an accurate placement of the final attachments with a slight vertical resiliency and hinge action is alsoprovided. The prosthesis uses two support mechanisms, the dental implants and the underlying bony ridge. The entire prosthesis is designed to distribute stress placed on both mechanismsby splinting the implant supports with a bar correctly placed for strength, function, and hygiene.

TREATMENT The IMZ dental implant systemconsistsof a two-phase implantation procedure that allows for a stress-freehealing phaseduring which the implants are totally immobilized. The period of immobilization is a prerequisite for predictable osteointegration of the bone and implants. Phase one includes the insertion of the implant and healing screw and the stress-freehealing period of 3 to 4 months.3*4 Phasetwo includes exposureof the submergedimplants after osteointegration is complete. The fabrication of the prosthesisis begun after impressionsand skeletal and occlusal relations are made. The placement of the healing post with the highly polished titanium transmucosalimplant extensions (TIE) allows the surrounding gingiva to adapt to the implant. During the secondphaseof implantation the implant cylinder height is increasedby meansof the TIE to ensurethat the stress-absorbingelementwill be in a supragingival position and available for cleaning and replacement.5 Fig. 2 illustrates the position of the three IMZ dental 331

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Fig. 1. Preoperative radiograph illustrates edentulous maxillae with severe bone loss in posterior regions. Fig. 2. Three IMZ dental implants. Healthy sulcular tissue is apparent. Fig. 3. Intramobile elements provide micromovement of prosthesis connectors. Fig. 4. Two distal-extension and one “overdenture” ERA attachments incorporated into connecting bar. Fig. 6. Labial view of positioning of attachments.

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Fig. 6. Nylon ERA distal extension attachment. Fig. 7. ERA overdenture attachment processedin acrylic resin.

implants with the TIE removed and the formation of a healthy keratinized s&us around the implants that is formed by the polished titanium TIE. The stress-absorbing intramobile element (IME), which imitates the mobility of the natural dentition, is placed supragingivally to provide easyaccessfor oral hygiene (Fig. 3). Physical integration of bone and implants, which occurs during phase one, is maintained throughout the stress-bearingfunctional life of the implants6 With the inflammation of the crestal and palatal mucoperiostealtissuescontrolled, an incision wasmadelabial to the crest of the miaxillary ridge from the right first molar to left first molar areas.The entire ridge was exposedto determine the width of the underlying bone. The area allowed for placement of two 4 mm width, 13 mm length implants in areasof the right and left maxillary caninesand a 4 mm width, 3 mlrnlength implant in the area of the right central incisor. The underlying anatomic structures would not allow for placement of additional implants. The tissues were allowed to heal for approximately 5 months, during which time the patient continued to wear her soft-relined maxillary denture. A maxillary preliminary impressionwas made by using irreversible hydrocolloid impressionmaterials in a custom tray madeover the preliminary cast. Careful consideration wasgiven to the baordersfrom tuberosity to tuberosity, including the pterygomaxillary notchesand posterior palatal region. A single thickness of baseplatewax was adapted over the cast to provide spacefor the final impressionmaterials. The tray was border molded and a final maxillary impressionof the implants and soft tissueswasmade.7*8 The position of the connecting bar wasdetermined once the wax trial denture wasfitted. The bar wasplaced over the crest of the ridge, or slightly lingual to it, and wasclose to but not in contact with the tissues to provide an

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environment conducive to patient oral hygiene. Jensen’s Spirit Series alloy (Jensen Industries Inc., New Haven, Conn.), a lightweight, strong, clean palladium-rich metal, was used becauseof its excellent wear resistance.g Figs. 4 and 5 illustrate the position of the splinting bar and the placementof the receptacle portion of the ERA attachments.Two “partial denture” attachmentswereplaced distal to the implants in the canine regionsto provide support asfar posterior aspossibleandthe third “overdenture” attachment wasplaced mesialto the implant in the incisor region to provide increasedanterior retention. The ERA attachments are the primary system of retention and stability. The white ERA attachment (Fig. 6) and the white overdenture attachment (Fig. 7), which have the lightest amount of retention, are more than adequate to retain the denture in all movements. The positioning of theseattachments followsthe arc of the alveolar ridge (Fig. 8). Becauseof the excellent retention and patient acceptance of the prosthesis,it was possibleto remove a large portion of the palatal acrylic resin from the maxillary denture (Fig. 9). On its insertion, the patient did not experience the gagreflex (Fig. 10). Postoperative placementof the bar is shownin Fig. 11. The total retentive system eliminated rotation and stabilized the prosthesis(Fig. 12).

DISCUSSION The edentulous state is often accompaniedby adverse functional and cosmetic consequencesthat are varyingly perceived by the patient. lo The denture-bearing tissues becomesmaller as the residual ridges resorb and the mucosahaslittle tolerance or adaptability to denture wearing. When the condition is accompaniedby a severe chronic physical or psychologicalgagreflex, the patient is left with a most difficult situation to treat. Proper denture fabrication requiresan understanding of

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Fig. Fig. Fig. Fig. Fig.

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8. Three ERA attachments processed in arc in maxillary overdenture. 9. Maxillary overdenture prepared with palate removed. 10. Final prosthesis in place illustrating open palate. 11. Final radiograph with connecting bar in place over IMZ implants. 12. Esthetic appearance of maxillary overdenture.

the anatomic and physiologic components of the edentulous regions. Ideally, maximal extensions can be designed to allow for contact of the mucous membrane and the denture base. However, neurologic influences may affect sali-

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vary secretions that may result in a decrease in retention. Many patients acquire an ability to retain their dentures by means of the oral musculature. However, an increase in muscle fixation may reduce the forces the patient uses in

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mastication and function, which may also reduce the patient’s ability to satisfy nutritional requirements. The dental implants placed in this situation will stabilize the maxillary prosthesis to an acceptable level. Only three implants could be used with the bone levels in the patient presented. The maxillary left incisor bone was too thin in the labial-palatal axis to allow for any type of implant design. One of the advantages of using the IMZ implant system is that it can minimize the stresses placed at the bone/metal interface with the use of the stress-absorbing intramobile elements. The bar system can be removed by simply unthreading the seating screws to allow for easy management and hygiene. The transmucosal implant extension permits a tight ada.ptation of the mucosal tissue to the polished TIE, which (contributes to the long-term success of the treatment. The ERA is a simple and effective retentive device because it has a variety of color-coded retention attachments. The synthetic attachments are easily and quickly removed and replaced when indicated. The attachments are durable, securely retaining the prosthesis for years before replacement is necessary. In some instances heavy calculus formation will change the surface of the nylon, thereby requiring replacement. Hence, denture maintenance is essential. ‘Because they are not rigid, they provide a comfort zone for the osteointegrated dental implant.

CONCLUSION Fabrication of a stable and retentive maxillary overdenture using dental j.mplants provides an excellent alternative to conventional prosthetic design, especially in the compromised patient. The IMZ dental implant system provides excellent retrievability and functional support and minimizes stresses on the bone with its stress-absorbing elements.

The design used with the ERA retention system including the new overdenture attachment permitted micromovement between the nylon attachment and metal receptacle portions. The appearance of the completed prosthesis was excellent because of the easy placement of the retainers. Patient acceptance was excellent, with no complaints regarding hygiene or loss of retention. The attachments also provided versatility to correct or improve retention, which may not be possible with other systems. REFERENCES 1. Cranin N. Oral implantology. Springfield, 111: Charles C Thomas, 1970:241-61. 2.. Mentag PJ, Kosinski TF, Sowinski LL. IMZ overdenture construction using the Stern ERA attachment. Gen Dent 1988$ept-O&399-2. 3. Kirsch A. The two-phase implantation method using IMZ intramobile cylinder implants. J Oral Implant. 1983;11:197-210. 4. Kirsch A, Mentag PJ. The IMZ endosseous two-phase implant system: a complete oral rehabilitation treatment and concept. J Oral Implant 1986;12:578-89. 5. Mentag PJ, Kosinski TF. Increased retention of a maxillary obturator prosthesis using osteointegrated intramobile cylinder dental implants: a clinical report. J P~UJSTHET DENT 1988;80:411-5. 6. Meroueth KA, Watanabi F, Mentag PJ. Finite element analysis of a partially edentulous mandible rehabilitated with osteointegrated cylindrical implant. J Oral Implant 1987;13:215-38. 7. Shifman A, Kusner W. A prosthesis fabrication technique for the edentulous maxillary resection patient. J PROSTHBT DENT 1986,56:586-92. 8. Mentag PJ, Kosinski TF. Increased retention of a maxillary obturator prosthesis using osteointegrated intramobile cylinder dental implants: a clinical report. J PROSTI-IW DENT 1988,60:411-415. 9. Lorenxana RE. Strength properties of soldered joints for a gold-palladium alloy and a palladium alloy. J PROS= DENT 1987;57:459-3. 10. Hickey JC, Zarb GA. Boucher’s prosthodontic treatment for edentulous patients. 9th ed. St Louis: CV Mosby, 1985:3-43. Reprint

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DR. PAUL J. MENTAG 15901 W. NINE MILE RD., STE. 206 SOUTHFIELD, MI 48075

Use of a multifunctional precision attachment in a fixed partial denture with limited periodontal support. A clinical report Lambert J. Stumpel, Breda, The Netherlands

D.D.S.,*

I

and Ruud W. Sips**

t is often difficult to determine the minimal amount of periodontal support necessary for prosthetic treatment *Private practice. **Certified Dental Technician. 10/l/22134

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of a particular patient. Occlusion, quality and position of existing abutment teeth, amount of remaining bone, and patient hygiene areonly afew of the many factors that must be evaluated in planning treatment for the periodontally compromisedpatient. For many years “Ante’s 1aw”l served as a reference for

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