Rpd Prosth

7/29/2019 Rpd Prosth

1/4

BRITISH DENTAL JOURNAL, VOLUME 186, NO. 6, MARCH 27 1999 273

PRACTICEtooth surface loss

RemovableprosthesesM. Faigenblum1

4

1Honorary Clinical Senior Lecturer,Department of Prosthetic Dentistry,Eastman Dental Institute for OralHealthcare Sciences, University ofLondon, 256 Grays Inn Road, LondonWC1X 8LD and Specialist in

Prosthodontics, 25 Devonshire Place,London W1N 1PDREFEREED PAPER

British Dental Journal1999; 186: 273276

The previous article discussed changes in theocclusion that take place when teeth wear.Severe wear, particularly when coupled withtooth loss, can produce marked changes in theocclusal relationships and significant aestheticdeficit. A removable prosthesis may be theappropriate restorative approach particularlywhen wear is advanced. Determination of thecorrect vertical dimension for the occlusionand an appropriate jaw relationship form the

basis of treatment whether this employs fixedor removable prostheses. Later articles willexamine both adhesive and more traditionalfixed approaches to restoration. However, thispaper describes the use of removable appliancesfor restoring dentitions affected by tooth sur-face loss and how the aesthetic and technicaldifficulties created by the lack of space may beovercome.

The maintenance of anterior facialheight by compensatory growthThe craniofacial complex is not a static entity

in the adult;1 there is evidence that growth,though slower than takes place during adoles-cence, continues into late middle age.2 Anaspect of such growth ie the increase in ante-rior facial height has been reported.24 One ofthe mechanisms for this increase (in theabsence of excessive tooth wear) is thought tobe from the eruption of teeth because of anincrease in alveolar height.5,6

Tallgren noted that with the complete denti-tion, anterior facial height tends to increase withage and that this increase is paralleled by the restof the face height;3 in other words, the free-way

space (FWS) remains constant. This relation-ship appears to hold as long as there is no appre-ciable destructive change in the dentition.

Where uniform wear of the occlusal surfacesand incisal edges does take place, Sicher sug-gests that this is compensated by continuousvertical eruption and thus attrition does notaffect the proportions of the face.7 Niswonger(cited by Tallgren3) among others6,8 supportedthis view. He found that 80% of severe wearcases had a normal FWS ie 3 mm.

However, there is a contrary view (Thomp-son,4 Mershon,9 and Kazis,10) which affirms

that the FWS is affected by wear and its mag-nitude is proportionate to the degree of attri-tion. Stern and Brayer11 state that:Pathological changes of the occlusion may

occur when posterior tooth support isreduced or lost. In these cases, the mandiblerequires a new support which is usually found inthe anterior region of the mouth. Consequently,an excessive occlusal load affects the anteriorteeth. Such an event is known as occlusalcollapse. Russell,12 supports this concept. Heconsiders that an FWS in excess of 56 mm isabnormal and that the occlusal wear which hasproduced it, has occurred at a rate faster than

the physiological mechanisms designed to com-pensate for it. This presumption is disputed in arecent paper by Smith and Robb.13

These apparently contrasting opinions arereflected in the following clinical observations.Dawson is adamant that as wear does notdecrease the occlusal vertical dimension(OVD), there is no case for its increase duringtreatment.14 Nonetheless, he subsequentlystates that: If the contacting surface enamel isworn severely on both the upper and loweranterior teeth, there is sometimes no room torestore the surfaces... without either invading

the pulp or increasing the vertical dimension.This type of problem is usually treated by open-ing the vertical. Watson and Tulloch too, find aseeming paradox in relation to OVD. Theycomment, that: Clinically one frequently findsthat despite considerable TSL there is very littleinterocclusal clearance...on the other hand...theextent of the freeway space is sometimes com-mensurate with a natural FWS together withthe TSL.

This apparent conflict can be resolved bymodifying Pindborgs original classification ofTSL.16 The latter makes a distinction between

generalised and localised tooth wear.12,16 Compensated TSL: Tooth surface loss with-

out loss of OVD. It generally involves a com-plete or nearly complete dentition and thefree-way space remains within the normalrange.

Non-compensated TSL: Tooth surface lossleading to the loss of OVD. This is often con-fined to the anterior segments and associatedwith a lack of posterior occlusion. The rate ofwear, confined to a smaller number of teeth,results in an apparent lack of compensatoryeruption and the free-way space is greater

than normal.With compensated TSL, the occlusal plane is

generally not in doubt. During treatment, theincrease in vertical dimension is usually

Reconstruction of the

dentition extensively

damaged through

tooth surface loss may

require the use of

removable prostheses.

This can be the most

appropriate type of

treatment when eitherthe teeth are very

severely worn or the

patient wishes a

simpler and more

economical approach

than a fixed

reconstruction.

The Series Editors are Richard Ibbetson

and Andrew Eder of the Eastman DentalInstitute for Oral Healthcare Sciencesand the Eastman Dental Hospital


2/4

274 BRITISH DENTAL JOURNAL, VOLUME 186, NO. 6, MARCH 27 1999


dependent on the space required to restore theteeth. Repositioning of the mandible will re-establish a normal FWS but the anterior lowerfacial height (ALFH) will be increased.

With non-compensated TSL, the collapse ofALFH necessitates an increase in the verticaldimension to restore the subjects to their pre-

sumed, original OVD before TSL took place.As patients with compensated TSL rarely pre-sent for removable partial denture (RPD) treat-ment, the following discussion will, in themain, be directed to non-compensated TSL.

Assessment of non-compensated TSLThe patient affected by non-compensatedTSL with loss of facial height poses the sameproblem as in complete denture prosthodon-tics; how to establish a functional OVD. Theabsence of an acceptable occlusal plane alsocomplicates the determination of an appro-

priate intercuspal position (ICP).Two characteristics may be of value in guid-ing the operator toward the optimal retrudedaxis position (RAP) and hence a convenientocclusal vertical dimension (OVD).17

Firstly, when teeth are found distal to theworn anterior surfaces, a facet may be presentwhich often appears to be coincident with theretruded contact position (RCP). (It will beobvious if this first contact is a result of over-eruption.) Secondly, this contact will fre-quently produce an acceptable OVD. This canbe confirmed by reference to the patients

appearance and in particular to an unstrainedrelationship of the lips in apposition.

Figures 1 to 5 illustrate this suggestion. Theunstable contacts seen in figures 3a and b maybe responsible for deflecting the mandible for-ward into ICP, a position to which the func-tional movements of mastication andswallowing are normally directed.18 The poste-rior contacts no longer being used, the anteriorteeth suffer progressive wear which is probablya combination of attrition and erosion.19 Whenthe mandible is held at the retruded contactposition, the original occlusal plane, common

to both arches, can be envisaged and there is nolonger any evidence of significant over-erup-tion. The outline of anterior tooth form can beextrapolated from the proportions of theremaining tooth structure and the availableinterarch space (fig. 4); a diagnostic wax-upwill show this more accurately.

Thus, an examination of the casts mountedin RCP, will often allow the operator to visualisethe degree of tooth loss and the extent ofrestoration required. This can be the startingpoint for the proposed restoration.

Treatment of non-compensated TSLThe following is a schematic outline for thetreatment of TSL with a removable prostheses.Management can be divided into three stages:1. Preliminary investigations2. Restorative phase3. Maintenance.

Preliminary investigations:

1. Routine examination2. Note the presence and position of facets and

their relationship on opposing teeth (this ismost easily seen on the casts)

3. Assess the amount of free-way space (FWS)4. Manipulate the mandible into RCP and

observe the effect on the facial appearance5. Make impressions of the complete arches

Fig. 1 Anterior view of a patients intercuspal position(ICP) showing exceptionally heavy wear of the upperincisors. Note the shiny surface of the apparently non-functional amalgam surface on the |5

Fig. 2a and 2b Lateral views of the casts in ICP. Theposterior segments are collapsed and there appears tobe gross over-eruption. Note the relationship of theapparently over-erupted upper second premolar teeth tothe lower first premolar. The arrows indicate the presenceof wear facets


3/4

BRITISH DENTAL JOURNAL, VOLUME 186, NO. 6, MARCH 27 1999 275


and verify the accuracy the resultant casts20

6. Make duplicates of these casts after blockingout undercuts

7. Using a measuring device (eg Willis BiteGauge) record the rest vertical dimension(RVD)

8. Take an interocclusal record at a jaw separa-

tion approximating the RVD recorded9. Note the occlusal vertical height (OVD)when the teeth are in ICP

10. Deduct the OVD from the RVD to obtainthe FWS

11. With the casts mounted and the interoc-clusal record in situ, note the reading on thescale of the incisal pin (ie this is equivalentto the RVD, see 8 above)

12. Close the articulator until first tooth con-tact and again take note of the reading onthe incisal pin. (If there is no posteriorcontact close the articulator until the

upper and lower occlusal planes appear tocoincide)

13. Close the articulator into ICP and note thereading at the incisal pin

14. Compare these results with those found invivo. If the first contact (or coincidence ofthe occlusal plane) produces an acceptableFWS and facial appearance, use this as aguide for restoration

15. An occlusal splint is constructed, asdescribed in Part 3 of this series. It is usuallymost convenient to construct a maxillaryappliance. Little, if any, alterations should

be made to the teeth at this stage. This is toallow abandonment of treatment with aminimum of recrimination. Teeth can beadded to the splint, making it, in effect, anoverlay denture. When adjustments andhabituation have produced a satisfactoryfunctional and aesthetic result, the nextstage can be embarked upon.

2. Restorative phase

The OVD and ICP having been established bythe upper occlusal splint, it is possible to envis-age two situations:

1. Where the lower dentition produces a satis-factory occlusal plane, there is no need for alower denture to complement the uppersplint/denture unless there are specific rea-sons eg aesthetics

2. Where the loss of teeth and tooth substancein the lower arch have created a need for alower denture to establish a harmoniousocclusal plane. The occlusal splint having fol-lowed the irregular lower occlusal plane, ititself is unaesthetic as it overlays the teeth.Two methods can be used:

The casts are articulated as described above

and the lower denture is waxed up to meetthe upper contacts, care being taken to pre-sent an harmonious occlusal plane to whichthe definitive upper denture can eventually

be made to occlude

The lower cast is articulated against a cast ofthe occlusal splint. An idealised occlusalplane is set up, stone from the opposingcast being removed to allow this. Thedefinitive lower denture is fitted andappropriate adjustments are made to thesplint.

Choice of the denture base materialThis will depend on various factors includingthe opposing materials and whether coverage ismainly on hard or soft tissue:

Fig. 3a and 3b Lateral views of the casts after themandible has been guided into RCP. Note that thefacets are now in contact and the apparentovereruption of the 753|578 has resolved into anacceptable occlusal plane

Fig. 4 Anterior view of the teeth in RCP. Note that thefacet on the upper left premolar is on the amalgamrestoration and its lustre indicates wear during function(figures 1 and 5). This is belied by its situation in ICP, asseen in figure 2b


4/4

276 BRITISH DENTAL JOURNAL, VOLUME 186, NO. 6, MARCH 27 1999


Because a well-supported denture is of pri-

mary importance; the best design for thedefinitive lower denture is based on a metalframework

The definitive upper denture will benefitfrom a metal construction if the splint hasshown signs of excessive wear resulting inbreakage

The final prosthesis can be veneered over itsentire occlusal surface with cobalt chromiumwhich will strengthen the appliance andavoid the need to attempt the reproductionof the appearance and functional occlusionde novo. When using cobalt chromium

attention must be paid to the likelihoodthat the opposing arch may suffer acceler-ated wear.

Management of the appearanceTwo options are available for restoring the wornteeth:1. Complete facings with or without a flange2. Butt joint.

The materials can be purpose-made acrylicfacings, hollowed-out denture teeth or custommade in the mouth with autopolymerisingresin, composite, or light curing resin. An opa-

quer may be necessary to mask the colour of ametal base. In the latter case, special provisionswill also need to be made for retention eithermechanically or chemically.

The choice of restoration will dependupon: Path of insertion of the denture The ability of the lip to tolerate labial cover-

age of the teeth The height of the lip during function ie if the

butt joint is visible The occlusion The ability to match the colour of the over-

laid tooth with the restorative material.

Maintenance

One objective of treatment is to produce anappliance which is resistant to degradation butnonetheless is capable of simple servicing atroutine checkups. Overlay dentures will nor-mally be worn at night to prevent parafunc-tional attrition of the teeth. If it is thought thatthis will place the denture at too much risk anocclusal splint may be substituted.

ConclusionThe article has discussed the effects of tooth sur-face loss on anterior facial height and how thiscan be related to the distribution of wear within

the mouth. Identification of the changes thathave taken place is important in making a com-plete assessment of the patient and forming arestorative plan. Removable appliances may bethe treatment of choice for some individuals,particularly when the time and cost of fixedrestorations are considered. The complexities oftreatment of the severely worn dentition serve tore-emphasise the importance of effective pre-vention as discussed in the first three parts ofthis series. There may also be a case for earlyrestoration to prevent the extensive damage tothe teeth which necessitates extensive recon-

struction. Parts 1 and 2 mentioned a possiblerole for early restorative intervention to min-imise further wear: this is sometimes consideredcontroversial as concerns have been expressedover wear continuing around the margins ofrestorations. However, there is merit in such anapproach, particularly if the restorative tech-niques are relatively non-invasive and it is cou-pled with an overall preventive approach. Part 5examines the role of adhesive dentistry in themanagement of the worn dentition.

This article is based on a presentation at The Medical Society ofLondon on 15 December 1994 as part of the Alpha Omega lecture

programme.

Fig. 5 The patients profile is seen in his rest position (fig. 5b)and at the RCP (fig. 5c). In ICP the patients lower anteriorfacial height is very much reduced. However, at RCP the facetakes on a more normal appearance. In particular note thatthe lips appear to be in unstrained contact

1 Crothers A, Sandham A. Verticalheight differences in subjects withsevere dental wear. Eur J Orthod1993;15: 519-525.

2 Behrent R G.Growth in the agingcraniofacial skeleton. CraniofacialGrowth series. Monograph No.17Center for Human Growth andDevelopment. Michigan: University

of Michigan, Ann Arbor, 1985.3 Tallgren A. Changes in adult faceheight due to ageing, wear and loss ofteeth and prosthetic treatment.ActaOdont Scand1957; 15: Suppl.24, 73.

4 Thompson J L, Kendrick G S.Changes in the vertical dimension ofthe human male skull during thethird and fourth decades of life.AnatRec1964; 27: 209.

5 Manson J D. Passive eruption. DentPract1963; 14: 2-8.

6 Murphy T. Compensatorymechanisms in facial heightadjustment to functional toothattrition.Aust Dent J1959; 4: 312-323.

7 Sicher H. Oral biology. St Louis, CVMosby Co. 1949 (in Tallgren 1957.)

8 Berry D C, Poole D F G. Attrition:possible mechanisms ofcompensation.J Oral Rehabil1976; 3:201-206.

9 Mershon J V. Possibilities andlimitations in the treatment ofclosed-bites.Int J Orthodont1937; 23:581-589 (in Tallgren A. 1957).

10 Kazis H. Complete mouthrehabilitation through restoration oflost vertical dimension.J Am DentAss 1948; 37: 19-39 (in Tallgren A.1957).

11 Stern N, Brayer L. Collapse of the

occlusion aetiology,symptomatology and treatment.JOral Rehabil1975;2: 1-19.

12 Russell M D. The distinction betweenphysiological and pathologicalattrition: a review. Ir Dent Assoc1987;33: 23.

13 Smith B G N, Robb N D. Theprevalence of toothwear in 1007dental patients.J Oral Rehabil1996;23: 232-239.

14 Dawson P. Evaluation, diagnosis andtreatment of occlusal problems. 2nded. Mosby-Toronto, 1989.

15 Watson I B, Tulloch E N. Clinicalassessment of cases of tooth surfaceloss. Br Dent J1985; 159:144-148.

16 Pindborg J J. Pathology of dental hardtissues. pp300-309. Copenhagen:Munksgaard, 1970.

17 Hemmings KW, Howlett JA,Woodley N J, et al. Partial denturesfor patients with advanced toothwear. Dent Update 1995; 22: 52-59.

18 Ramfjord S P. Bruxism, a clinical andelectromyographic study.JADA 1961;62: 21-44.

19 Lewis K J, Smith B G N. Therelationship of erosion and attritionin extensive tooth tissue loss. Br DentJ1973; 135: 400-404.

20 Faigenblum M J. Advice onproducing an accurate impression

and working cast for construction ofpartial dentures. Br Dent J1985; 159:45-46.

a b c

Rpd Prosth

Documents

Transcript of Rpd Prosth