258 BRITISH DENTAL JOURNAL VOLUME 200 NO. 5 MAR 11 2006

Management of the flabby ridge: usingcontemporary materials to solve an old problemC. D. Lynch1 and P. F. Allen2

The presence of displaceable denture-bearing tissues often presents a difficulty when making complete dentures. Unlessmanaged appropriately, such ‘flabby ridges’ adversely affect the support, retention and stability of complete dentures. Manyimpression techniques have been proposed to help overcome this difficulty. While these vary in approach, they are similar intheir complexity, are often quite time-consuming to perform, and rely on materials not commonly in use in contemporarygeneral dental practice. The purpose of this paper is to describe an impression technique for flabby ridges that makes use ofpolyvinylsiloxane impression dental materials routinely available in general dental practice.

1*Registrar in Restorative Dentistry, Department ofRestorative Dentistry, National University of Ireland, Cork,Ireland; 2Senior Lecturer/Consultant, Department ofRestorative Dentistry, National University of Ireland, Cork,Ireland*Correspondence to: Dr Christopher D. LynchEmail: c.lynch@ucc.ie

Refereed PaperAccepted 10 October 2005doi: 10.1038/sj.bdj.4813306© British Dental Journal 2006; 200: 258–261

INTRODUCTIONThe performance of a complete denture isoften a reflection of its support and reten-tion.1 A master impression for a completedenture should ‘record the entire functionaldenture-bearing area to ensure maximumsupport, retention and stability for the den-ture during use’.2 However difficulties arisewhen the quality of the denture bearingareas are not suitable for this purpose. Dis-placeable, or ‘flabby ridges’, present a par-ticular difficulty and may give rise to com-plaints of pain or looseness relating to acomplete denture that rests on them.3 Pub-lished studies indicate that the prevalenceof flabby ridges can vary, occurring in upto 24% of edentate maxillae and in 5% ofedentate mandibles.4,5 Historically, flabbyridges found in the anterior maxilla were afeature of the ‘combination syndrome’.6,7 In

this ‘condition’, the flabby ridge wasthought to occur as a result of a maxillarycomplete denture opposing mandibularanterior natural teeth, without proper pos-terior occlusal support. Such flabby tissuescould also arise as a result of unplanned oruncontrolled dental extractions.8

A variety of techniques have been sug-gested to circumvent the difficulty of mak-ing a denture to rest on a flabby ridge. Ithas been stated that while the flabby ridgemay provide poor retention for a denture,it is better than no ridge — as could occurfollowing surgical excision of the flabbytissues.4 A multitude of impression tech-niques have been suggested in the past tohelp record a suitable impression of a flabbydenture-bearing area. When consideringthese, it is important to realise that allimpressions for complete dentures couldbe categorised in three ways:1. The mucostatic technique (non-

displacive),9

2. The mucocompressive technique (displacive),10,11

3. The selective pressure impression tech-nique — where some denture bearing tissues are displaced, and others are not.12

A mucostatic impression technique9

records the un-displaced denture bearing

areas at rest. As the resultant denture ismore closely adapted to the underlying tis-sues at rest, it is theoretically more reten-tive. However, occlusal forces will not beevenly distributed across the underlyingdenture bearing area. In contrast, a muco-compressive impression technique10,11

compresses the underlying tissues in amanner similar to the way in which theresultant denture will compress the under-lying tissues. In this fashion, the resultantocclusal forces will be more evenly distrib-uted across the denture bearing tissues.While there is much speculation in thedental literature regarding the most suit-able impression technique for a completedenture, there is no evidence to indicatethat one technique produces better long-term results than the other.12 In practice,most impression techniques for conven-tional dentures could effectively be con-sidered ‘selective pressure’ techniques.12 Ifclose-fitting custom trays and high viscosityimpression materials are used, the soft tis-sues at the vibrating line on the palate arecompressed, while the tightly boundmucosa on the hard palate is not.13

A particular problem is encountered if aflabby ridge is present within an otherwise‘normal’ denture bearing area. If the flabbytissue is compressed during conventional

Having read this article, the reader will: Appreciate the challenges presented by a flabby ridge when constructing complete dentures. Understand the various techniques and materials available when making suitable impressions

of edentulous ridges containing flabby tissues. Be able to make a suitable impression of a flabby ridge using contemporary materials.

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impression making, it will later tend torecoil and dislodge the resulting overlyingdenture.3 Clearly, an impression techniqueis required which will compress the non-flabby tissues to obtain optimal support,and, at the same time, will not displace theflabby tissues.

A multitude of impression techniqueshave been described for overcoming theproblem of the flabby ridge. Liddlelow14

described a technique whereby two sepa-rate impression materials are used in a cus-tom tray (using ‘plaster of Paris’ over theflabby tissues, and zinc oxide and eugenolover the ‘normal’ tissues). Osborne15

described a technique whereby two sepa-rate impression trays and materials are usedto separately record the ‘flabby’ and ‘nor-mal’ tissues, and then related intra-orally.Watson16 described the ‘window’ impres-sion technique where a custom tray is madewith a window or opening over the (usuallyanterior) flabby tissues. A mucocompres-sive impression is first made of the normaltissues using the custom tray and zincoxide and eugenol. Once set, it is removed,trimmed, and re-seated in the mouth. A lowviscosity mix of ‘plaster of Paris’ is thenpainted onto the flabby tissues through thewindow. Once set, the entire impression isremoved. Each of these techniques mightbe considered cumbersome, and the diffi-culties associated with their manipulationcould lead to inaccuracies. Watt andMcGregor17 — recently revisited by Lynchand Allen18 — described a technique whereimpression compound is applied to a modi-fied custom tray. The thermoplastic proper-ties of this material are then manipulated tosimultaneously compress the ‘normal tis-sues’, while avoiding displacement of the‘flabby tissues’ using the same material andimpression tray. Over this manipulatedimpression compound, a wash impressionwith zinc-oxide and eugenol is made.While this final impression technique isclearly less complex that the previous threedescribed, the problem with all four tech-niques is that they rely on materials such as‘plaster of Paris’, impression compound,and zinc-oxide and eugenol. Many generaldental practitioners now rely on ‘newer’,more ‘easy-to-use’ materials, such aspolyvinylsiloxanes (silicones), particularlyfor fixed prosthodontics.19,20

The purpose of this paper is to describean impression technique for makingimpressions of denture bearing areas con-taining flabby ridges, which uses a simpli-fied technique and more widely usedimpression materials.

CLINICAL REPORTA 62-year-old female was referred by hergeneral dental practitioner to the Depart-ment of Restorative Dentistry of the Cork

University Dental School and Hospital,(Cork, Ireland) for specialist treatmentregarding her prosthodontic rehabilitation.The patient reported that she had recentlybeen provided with a maxillary completedenture, which she described as ‘loose’. Thiswas her second complete maxillary denturesince being rendered edentulous five yearspreviously and she had found both unsatis-factory. On examination, the patient waspartially dentate, with no teeth present inher maxilla, and 12 teeth present in hermandible (Fig. 1). It was noted that therewas an extensive area of flabby tissue pres-ent on the anterior region of her maxillarydenture bearing area.

Following discussion with the patient

regarding the available treatment options,it was clear that she was anxious to avoidsurgical procedures such as implants. Itwas decided to provide her with a newmaxillary complete denture, paying atten-tion to the impression technique, and toappropriately design the occlusal scheme.

A primary impression of the maxillarydenture bearing area was made with a lowviscosity irreversible hydrocolloid material(‘Alginate’; Dentsply Ltd-UK, Weybridge,Surrey, UK), to ensure minimal distortionof the displaceable (‘flabby’) tissues. Theimpression was poured in dental stone. Thedisplaceable areas were identified on thecast (Fig. 2). Three uniform thicknesses ofdental wax (‘Doric Toughened Wax’; DavisSchottlander and Davis Ltd, Herts, UK)were placed as a ‘spacer’ over the displace-able areas identified on the cast and onethickness over the remaining non-dis-placeable areas. The custom tray was fabri-cated in the usual manner. Following fab-rication, the custom tray was perforatedover the areas of the primary cast repre-senting the flabby tissues (Fig. 3).

At the chair-side, the custom tray wasinserted into the mouth and any over-extended areas of the periphery werereduced. The master impression was thenmade as follows:

After application of a suitable adhesive,heavy bodied addition-curing polyvinyl-siloxane (Extrude® polyvinylsiloxane

impression material; Kerr, Romulus, MI,USA) was applied to the area of the customtray associated with the ‘normal’ tissues.Once set, it was removed from the mouth.

Using a scalpel, any material that hadflowed into the area of the tray associatedwith ‘flabby’ tissues was removed. Heavybodied impression material was then appliedto the periphery of the custom tray. This wasplaced in the mouth, and the heavy bodiedpolyvinyl siloxane was border-moulded inthe usual manner. Once this had set, the traywas removed from the mouth (Fig. 4).

The area of the custom tray associatedwith the ‘flabby’ tissues was then filled

Fig. 1 Dental panoramic tomograph of patientdescribed in clinical report (caries in 45 (LR5)and 46 (LR6) were treated in the conventionalmanner)

Fig. 2 Displaceable areas identified on primarycast

Fig. 3 The perforated custom tray

Fig. 4 The custom tray with the periphery border-moulded and the fitting surface over thecompressible tissues recorded using heavy-bodiedpolyvinylsiloxane

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with light bodied polyvinylsiloxaneimpression material. A wash of light-bod-ied polyvinylsiloxane impression materialwas also placed over the heavy bodiedmaterial that had compressed the ‘normal’tissues. This tray was placed in the mouthand allowed to set.

Once set, the impression was removedfrom the mouth and inspected (Fig. 5). Anyexcess material was removed. The impres-sion was re-inserted to ensure that it wasretentive and did not rock when pressurewas applied over the displaceable areas.Caution is advised with the use of polyvinyl-siloxane impression materials, as inaccuratemanipulation can lead to over-extension ofthe impression.

The impression was cast in dental stone,paying careful attention to preserving the

bordered moulded sulcus area. A heat-curedacrylic transparent baseplate was fabricatedto assess the accuracy of fit. Denture fabri-cation then continued in the usual manner.Following face-bow transfer, the technicianwas instructed to arrange the teeth on asemi-adjustable articulator (Denar AnamarkFossae; Teledyne Water Pik), achieving bal-anced articulation, and paying attention toeven tooth contact in excursive movements.The dentures were delivered, and at subse-quent review appointments the patientreported satisfaction with stability, aesthet-ics and function (Fig. 6).

DISCUSSIONThe profile of patients who present for com-plete dentures, or replacement completedentures, is now more aged than it was 30

years ago.21,22 As a result of advances indental techniques and dental treatmentphilosophies, more patients retain some, orall, of their natural teeth until later inlife.23 Sometimes, unusual arrangementsof remaining natural teeth can lead tounfavourable distribution of occlusalforces on residual alveolar ridges, result-ing in bone resorption and development offlabby tissues. As a result of accompany-ing medical conditions or medical treat-ments such elderly patients may be unsuit-ed for surgical procedures such as removalof flabby ridges, bone grafting, or place-ment of dental implants. The description ofthis new impression technique is thereforetimely. It describes how the managementof poor denture-bearing areas can beaccomplished by expanding on the basicprinciples of complete denture construc-tion without recourse to surgically inva-sive procedures.

A presenting complaint of a completedenture that has been made for a flabbyridge, without proper care being taken toavoid compressing the flabby tissues, isthat the denture ‘is loose’. A commonapproach to solving a ‘loose’ completedenture is to apply some chairside relinematerial.3 It will be appreciated that thisapproach is inappropriate and will notsolve the problem — the complete denturewill act as a custom tray, and with the vis-cous chairside reline material will furtherdisplace the flabby tissue. The tissues willonce again tend to recoil and the denturewill still be ‘loose’.

The technique described does notinvolve extra clinical stages in the con-struction of a complete denture, therebykeeping clinical time to a minimum. Theimpression technique can be accomplishedrelatively quickly, and uses materials withwhich the general dental practitioner isalready familiar. There is no need for thepractitioner to apprehensively use materi-als that they may have little experience ofusing. Polyvinylsiloxanes are dimension-ally stable and do not need to be pouredimmediately. They are also less brittle than‘plaster of Paris’ and do not need to behandled as carefully.3

Other treatment modalities for the sce-nario described in this article include sur-gical ‘debulking’ or excision of the flabbytissues, and the use of dental implants.Surgical ‘debulking’ of flabby tissues ismainly a historical concept nowadays. Therationale behind its use was that removalof flabby tissues would result in a ‘normal’compressible denture bearing area onwhich a mucocompressive impressiontechnique could be used. Some of the diffi-culties caused by this approach include thefact that many complete denture patientsare elderly or have complex medical histo-

ries, for which any form of surgery is con-traindicated. Furthermore, the excision offlabby tissues and resultant ‘shallow’ ridgemay provide little retention or resistanceto lateral forces on the resultant denture.One is reminded of the concept thatprosthodontic therapy should be con-cerned with the ‘conservation of whatremains, rather than the meticulousreplacement of what has been lost’.24 Theuse of dental implants in this scenario isalso not without difficulty. It is clear that ifthere has been excessive bone resorptionand replacement by flabby tissues, thenthere will be little bone remaining intowhich dental implants can be placed.While it would be technically possible toaugment the remaining ridge with bonegrafts, the prognosis of such treatmentwould be questionable. Furthermore, thereare a group of patients who for a variety ofclinical or medical reasons are unsuited fordental implant treatment. There are alsosome patients who do not wish to havesurgically invasive procedures such asplacement of dental implants.

It is worth noting two further itemsfrom the technique described. Firstly, aftercompletion of the master impression, it iscrucial to ensure that the occlusal plane isproperly orientated, and that a suitableocclusal scheme with proper balancingcontacts in excursive movements isachieved. The use of a face-bow transferand arrangement of the teeth on a semi-adjustable articulator can facilitate this. Itis important to realise that an incorrectlyoriented occlusal plane, or incorporationof displacing occlusal contacts, will fur-ther destabilise a denture that is relying onpoor quality denture-bearing tissues.25 Theefforts to secure an adequate impressionwill have been wasted. Secondly, the use ofa transparent acrylic heat-cured base per-mits rapid assessment of the accuracy ofthe impression technique. Using a trans-parent base allows rapid visualisation ofthe adaptation of the base to the underly-ing denture bearing areas. Ingress of aircan be rapidly noticed, and movement ofthe base can be observed in associationwith specific movements.

CONCLUSIONThis paper has described an impressiontechnique for management of a denturebearing area that contains flabby tissues.The materials used are readily availableand used in contemporary general dentalpractice. The technique does not requireadditional clinical visits compared tofabrication of a conventional completedenture. The time required for the spe-cialised impression technique is notexcessive. This technique can be readilycompleted by the general dental practi-

Fig. 5 The completed master impression

Fig. 6 The completed denture

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tioner, allowing flabby ridge completedenture cases to be managed in a primarydental care setting.

1. Fenlon M R, Sherriff M, Walter J D. Comparison ofpatients’ appreciation of 500 complete dentures andclinical assessment of quality. Eur J Prosthodont RestDent 1999; 7: 11-14.

2. The British Society for the Study of ProstheticDentistry. Guidelines in prosthetic and implantdentistry. London: Quintessence, 1996.

3. Basker R M, Davenport J C. Prosthetic treatment of theedentulous patient. 4th edn. Oxford: Blackwell, 2002.

4. Carlsson G E. Clinical morbidity and sequelae oftreatment with complete dentures. J Prosthet Dent1998; 79: 17-23.

5. Xie Q, Nähri T O, Nevalainen J M et al. Oral status andprosthetic factors related to residual ridge resorptionin elderly subjects. Int J Prosthodont 1997; 55: 306-313.

6. Kelly E. Changes caused by a mandibular removablepartial denture opposing a maxillary completedenture. J Prosthet Dent 1972; 27: 210-215.

7. Lynch C D, Allen P F. The ‘combination syndrome’revisited. Dent Update 2004; 31: 410-420.

8. Allen P F, McCarthy S. Complete dentures fromplanning to problem solving. London: QuintessencePublishing, 2003.

9. Addison P I. Mucostatic impressions. J Amer DentAssoc 1944; 31: 941.

10. Fournet S C, Tuller C S. A revolutionary mechanicalprinciple utilised to produce full lower denturessurpassing in stability the best modern upperdentures. J Amer Dent Assoc 1936; 23: 1028.

11. Applebaum E M, Rivette H C. Wax base developmentfor complete denture impressions. J Prosthet Dent1985; 53: 663.

12. McCord J F, Grant A A. Impression making. Br Dent J2000; 188: 484-492.

13. Jacob R F. The traditional therapeutic paradigm:Complete denture therapy. J Prosthet Dent 1998; 79:6-13.

14. Liddelow K P. The prosthetic treatment of the elderly.Br Dent J 1964; 117: 307-315.

15. Osborne J. Two impression methods for mobilefibrous ridges. Br Dent J 1964; 117: 392-394.

16. Watson R M. Impression technique for maxillaryfibrous ridge. Br Dent J 1970; 128: 552.

17. Watt D M, MacGregor A R. Designing completedentures. 2nd edn. Bristol: IOP Publishing Ltd, 1986.

18. Lynch C D, Allen P F. Management of the flabby ridge:

re-visiting the principles of complete dentureconstruction. Eur J Prosthet Rest Dent 2003; 11: 145-148.

19. Lynch C D, Allen P F. Quality of written prescriptionsand master impression for fixed and removableprosthodontics: a comparative study. Br Dent J 2005;198: 17-20.

20. Lynch C D, Allen P F. Quality of communicationbetween dental practitioners and dental techniciansfor fixed prosthodontics in Ireland. J Oral Rehab2005; 32: 901-905.

21. O’Mullane D, Whelton H. Oral health of Irish adults.Dublin: The Stationary Office, 1992.

22. Kelly M, Steele J, Nuttall N, et al. Adult Dental HealthSurvey — Oral Health in the United Kingdom 1998.London: The Stationary Office, 2000.

23. Woolfardt J F, Han-Kuang T, Basker R M. Removablepartial denture design in Alberta dental practices. JCanad Dent Assoc 1996; 62: 637-644.

24. DeVan M M. The nature of the partial denturefoundation: Suggestions for its preservation. JProsthet Dent 1952; 2: 210-218.

25. Carr A B. Single complete dentures opposing naturalor restored teeth. In Zarb G A, Bolender C L, CarlssonG E (Eds). Boucher’s prosthodontic treatment foredentulous patients. 11th edn. St Louis: Mosby, 1997.

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