Three-dimensional analysis of maxillary denture displacement during reline impression procedure

PENHALL,

especially important, therefore, to consider alternative explanations for the nonexperimental findings. In particular, the potential for bias from the nonrandom allocation of patients to groups B and C needs to be considered. The reasons why patients in Group C did not receive surgery included the following: 1. A history of major surgery and a desire to avoid further surgery: Subcategory 1 (7 patients) 2. Medical histories that contraindicated surgery: Subcategory 2 (49 patients) 3. A history of having tolerated dentures successfully under adverse conditions combined with the desirability of avoiding unnecessary surgery: Subcategory 3 (29 patients) 4. Major bone loss with little remaining mandible to support dentures: Subcategory 4 (6 patients) It might have been expected that patients in subcategory 4 would have fared poorly. Two (33.3%) of these were found to require three or.. more visits. This is essentially the same proportion as the 32.1% (18 of 56) for those in subcategories 1 and 2, for whom a relatively favorable outcome would have been anticipated. Notably, these proportions are higher than the 7% for group B patients, who were treated surgically. Patients in subcategory 3 might have been expected to have an excellent prognosis, since they had a history of tolerating dentures successfully under adverse circumstances. Nevertheless, with 10.3% (3 of 29) requiring at least three postinsertion visits, they did not perform better than group B patients. While the results of this study point to a positive impact of surgery on postinsertion comfort, the potential for confounding effects cannot be excluded. It would be ideal, therefore, if these findings could be confirmed with data from a randomized trial. In addition, since muscle attachments tend to re-form in time, it would be desirable to investigate the outcome in the longer term.

Three-dimensional analysis displacement during reline Nikzad Hamdi

S. Javid, D.M.D., M.Sc., M.Ed.,* A. Mohammed, D.D.S., M.Sc.D.,

RODER,

AND

ESTERMAN

SUMMARY Of 521 patients referred to a specialist prosthodontic practice for complete dentures, 274 were considered as candidates for simple surgery to smooth prominent mylohyoid ridges before denture construction. Of these, 183 were thus treated. The remaining 91 did not receive surgery because of personal preference, underlying medical conditions, or other reasons. The percent who required three or more postinsertion visits to achieve comfort with their dentures was 7% for those who received surgery, 27% for those who required but did not receive surgery, and 17% for those not deemed to require surgery. This suggests that the surgical smoothing of prominent mylohyoid ridges may markedly improve patients’ tolerance of dentures in the short term. However, the potential for confounding from extraneous factors in these nonexperimental circumstances must be considered. REFERENCES I.

2. 3. 4. 5.

6. 7.

,\ustralian Bureau of Statistics. Prqjeuions of the population of South Australia. 1981-2021. Adelaide. 1983. ilustralian Bureau of Statistics. Fitzpatrick BN: Current concepts in the surgical management of the atrophic mandible. Brown LJ: Surgical Dm J 95:215, 1953. Downton 1954. Roberts improving 142:151, Armitage England, Engelman Statistical

Aust solution

1~: Mylnhyoid BJ: The sucwss 1977.

Dent J 23:344, 1978. to a lower denture ridge

eflicacy of the with the romp&

resection. mylohyoid lower

DenL ridge denture.

problem Ret

Br 74~212,

reseuion Br Dent

in J

P: Statistical Methods in Medical Research. Oxford, 1974, Blackwell Scientific Publicarions, pp 385-388. L: PLR. Srepwise logistic regression. In: BMDP Sofrware. 1981. Berkeley. 1981, University of Califor-

nia.

of maxillary denture impression procedure

Cecile G. Michael, B.Ch.D., H.D.D., M.S.,** Ph.D.,**+ and Frank A. Colaizzi, D.M.D.****

University of Florida, Collegeof Dentistry, Gainesville,FIa. *Professor, **Associate ESY Pt.

232

Department Professor,

of Removable Cairo University,

Prosthodonrics. Faculty of Dentistry,

Cairo,

***Prufessor, ****Awxiatr Prosthodontics.

Department Professor

of Dental BiomaterAs. and Chairman, Depx’ment

AUGUST

1985

VOLUME

of Removable

54

NUMBER

2

DISPLACEMENT

IN RELINE

IMPRESSIONS

Relining complete dentures is a service to patients that will reestablish adequate adaptation of the denture base to the bearing surfaces. However, prosthodontists regard relining as a complicated procedure that requires skillful clinical judgment. Ostrem’ reported that relining complete dentures is an obligation and a real service of dentists to patients. Chase* pointed out that although relining is not really satisfactory from any standpoint, it must be done in certain circumstances. Tucker’ noted that all dentists have memories of unpleasant experiences with complete denture relining. Various techniques have been suggested to overcome the pitfalls that can occur in the relining procedure.+’ One problem is to maintain the dentures in correct relationship with the underlying tissues while the impression is being made. This is important for esthetics, proper facial support, and proper alignment of the teeth to the residual ridges. This investigation was undertaken to determine changes in the three-dimensional position of the maxillary complete denture that results from the impression for relining. Four common impression materials were used with opened- and closed-mouth impression techniques. LITERATURE

REVIEW

Jaw relationship Several authors recommended making closed-mouth impressions for relining using the existing centric occlusion and intercuspation of the dentureshe’” Others prefer to make a new centric relation record with wax or modeling compound and then make the impression with the patient closing on the premade interocclusal record.‘, “-‘* Buchman’” described a method using a central bearing device and a needle-point tracing to establish the jaw relations when dentures are relined. Boucher2” advocated use of the dentures for making maxillary and mandibular impressions independently with an open-mouth technique. A new centric relation record would then be established and verified, and the occlusion adjusted accordingly.

Impression

materials

’

Various materials have been used for making impressions for relining. The choice depends on the preference and experience of the dentist, the quality of the bone of the residual ridges, and the soft tissues that cover them. Ostrem’ and Hardy 2’ devised a sectional impression technique using paraffin and low-fusing waxes. Several investigators recommend the use of a thin mix of rubber-base impression material after escape holes are cut in the labial flanges of the denture.2~‘5~‘6~22Others recommend the use of a thin film of free-flowing zinc oxide and eugenol impression paste for the relining procedures.‘4 ‘8-2oJordan” used a two-step impression procedure using zinc oxide and eugenol impression paste THE

JOURNAL

OF PROSTHETIC

DENTISTRY

Fig. 1. The contourmeter.

for recording the basal seat and fast-setting plaster to cover the wide open area on the palate. Several reports favor the use of tissue-conditioning material for making impressions for relining as well as for restoring the health of the tissues.3-5~22-26

MATERIAL

AND METHODS

Six patients with complete dentures were selected for this study. They wore slightly loose maxillary dentures with acceptable esthetics and occlusion. An interocclusal record was made with grey stick modeling compound and stored in cold water. A contourmeter2’ was used for measuring denture displacement in the three coordinates (Fig. 1). An occlusal index was prepared for the maxillary denture. The denture was then prepared to fit the ends of the three legs of the positioning tripod of the contourmeter. Three 1 mm deep reference depressions were made with a No. 8 rosebur in the basal seatsurface of the denture. One anterior reference point (R,) was placed on the left side of the incisive fossa in the canine resin and two posterior points (R2-R3)were placed one on each sidein the region of the maxillary tuberosities. The size of each reference point correspondedexactly to the end of each leg of the positioning tripod. The legsof the tripod were of equal length and the distancebetweenwas adjustable. The tripod cannot be rotated relative to the stylus holder of the contourmeter; therefore, the two posterior referencepoints were always horizontally aligned. The tripod legs were locked in position to fit the three reference points in the denture. The denture was seated on the occlusalindex, and the tripod was firmly attached to the reference points. They were carried together where the tripod was fastenedto the stylus holder and the occlusal index was fastened to the survey baseof the mounting stage, which was then kept in place for the duration of the procedure. Once the index was properly oriented in its permanent position, the tripod was removed and replaced by the stylus. The positions of the three reference points were 233

Fig. 2. Recording reference points in X and Y axis.

Fig. 4. Reference points were verified after making impression to determine accuracy of denture position

Table I. Average vertical (Z) displacements of maxillary complete denture in Z axis

Z-axis coordinate

Fig. 3. Recording reference points in Z axis was done with dial gauge.

oriented in three dimensions by recording their X, Y, and Z coordinates (Figs. 2 and 3). The denture was removed from its occlusal index and prepared for the impressions by grinding about 1.5 mm from the entire tissue surface except in the regions of the three reference points. All undercuts were removed from the labial and buccal flanges, the labial notch was broadened and deepened, and the borders were shortened by 1 mm to permit the impression material to form a new border. A 2 to 3 mm diameter hole was drilled through the median part of the rugae region of the denture to allow escape of the excess impression material. A fine mark was made with a No. 169L rose bur on the polished surface of the denture opposite each reference point. The three reference points were covered with small circular pieces of tinfoil before each impression was made. Four relining impressions were made for each denture with the closed-mouth technique using zinc oxide and eugenol impression paste (Qpotow Type I hard, Teledyne Dental Products, Elk Grove Village, Ill.), light-bodied polysulfide rubber (Permlastic Type III, Sybron/Kerr, 234

Closed-mouth technique -R L T E

C>pen-mouth technique R

E

L

Romulus, Mich.), regular-bodied polysuhide rubber (Polysulfide low viscosity, Sybron/Kerr), and a tissueconditioning material (Coe Comfort, Coe Laboratories, Chicago, Ill.). The three other impressions were made with openmouth technique2” using zinc oxide and eugenol paste (Opotow), light-bodied polysulhde rubber (Permlastic), and regular-bodied polysulfide rubber (Polysulfide). After making each impression, the three reference points were carefully exposed by cutting the impression material with a sharp knife opposite the points marked on the polished surface of the denture, and the tinfoil was removed to expose the three reference points. The impression material covering the border of the denture, not being part of the study, was reduced to prevent interference with the stylus of the measuring micrometer. The denture was reseated on its occlusal index, and the three-dimentional positions of R,, R?, and R, were again verified (Fig. 4). The X, Y, and Z, coordinates were then recorded for the following working points (Figs. 5 and 6): R:, which was 7 mm medial to R,; Rg, which was 7 mm anterior to R,; R:, which was 7 mm anterior to R,. Point I denoted the position of the incisive fossa, and point P denoted the AUGUST

1985

VOLUME

54

NUMBER

2

DISPLACEMENT

IN RELINE

IMPRESSIONS

Table II. Average lateral (X) displacement of maxillary complete denture in X axis

X-axis point

Closed-mouth _ E R

Ouen-mouth technique

technique L

T

E

R

L

I

0.48

0.33

0.39

0.29

0.66

0.54

1.19

P

0.79

0.84 0.62

0.55 0.42

0.85 0.76

0.81 0.68

0.37 0.78

0.32

0.18

0.13

0.19

0.58

Mean

0.64

0.79 0.56

SD

0 22

0.32

1 = Inckivr papilla, P = deepest atltlitional definition5.)

poinr

of palate.

(See Table

I for

Table III. Average forward (Y) displacement of maxillary complete denture in Y axis

Y-axis point I P

Mean SD

Closed-mouth

Fig. 5. Thickness

of impression or to R3, R,, and RZ.

E

R

L

T

E

R

L

1.40 078

1.73

0.95

0.81

1.09

0.47

0.31

1.18

1.70

0.93

0.89

0.76

1.09

1.41

0.71

0.44

0.45

0.34

0.56 0.35

1.04 0.21

0.40

1.23 0.66

0.67 0.27

RESULTS The average change of the three working points Ri , Ri, and R 4 in the 2 axis (Table I) indicated the vertical displacement of the maxillary denture. The light-bodied polysulfide elastomer showed the least vertical displacement for both the open- and closed-mouth techniques, 1.25 and 1.47 mm, respectively. No significant difference existed in the vertical displacement of the maxillary denture when each of three impression materials was used with the open- or the closed-mouth technique. The average changes in position of the incisive fossa (working point I) and the deepest point of the palate (working point P) in relation to the X axis denoted the lateral displacement of the maxillary denture. As shown JOURNAL

OF PROSTHETIC

7 mm anteri-

Open-mouth technique

technique

deepest point of the palate (corresponding to the median palatine raphe and torus palatinus) and its relation to R,. Thus the three coordinates of five working points were determined for each impression in addition to the three reference points. Denture displacement in the three dimensions was determined by comparing the three coordinates of each of the five working points to the three coordinates of each reference point. All calculations were made in millimeters, although the numbers do not represent the actual thickness of the impression materials. Measurements were made up to 0.01 mm as recorded by the contourmeter. The data collected were statistically analyzed.

THE

measured

DENTISTRY

Fig. 6. Deepest part of palate as working sponded with median palatine raphe torus.

point P correor maxillary

in Table II, the tissue-conditioningmaterial showedthe least displacement (0.42 mm) in the lateral direction. When the open- and closed-mouthtechniques are compared the closed-mouth technique showed slightly less lateral displacement than the open-mouth technique with the impression materials used. However, this difference was statistically insignificant (p < .05). The average change in position of points I and P in relation to the Y axis (Table III) indicated the forward displacement of the maxillary denture. The tissueconditioning material showed 0.56 mm forward displacement (least of all the impressionmaterials). Lightbodied polysulfide showed 0.67 and 0.71 mm with the open- and closed-mouth techniques, respectively, which was lessthan the forward displacement causedby the other two impressionmaterials (zinc oxide and eugenol and regular-bodied polysulfide). The total denture displacement in the three dimensions (Table IV) indicated that the tissue-conditioning material and light-bodied polysulfide, used with either 235

Fig. 7. Tissue-conditioning materials and light-bodied polysulfide showed minimum displacement.

Table IV. Maxillary in three dimensions

denture

displacement

Closed-mouth technique

Lateral displacement X axis Forward displacement Y axis Vertical displacement Z axis

Open-mouth technique -___ E R

E

R

L

T

L

0.54

0.56

0.62

0.42

0.76

0.68

0.77

1.09

1.41

0 71

0.56

1.04

1.23

0.67

1.92

1.84

1.47

1.59

I.75

I.?2

1.25

SUMMARY

technique, showed less denture displacement than the regular-bodied polysulfide and the zinc oxide and eugeno1 impression paste (Fig. 7). Statistical analysis of the results does not show any significant difference in the amounts of denture displacement in the three dimensions when the impressions were made with the open- or closed-mouth technique (p < .05). DISCUSSION The results obtained in this study showed less denture displacement in the three dimensions with tissue-conditioning material and light-bodied polysulfide impressions. This could be due to the high degree of flow that such materials possess.15, ‘6.24.25 The minimal lateral and forward displacement of a maxillary denture when an impression is made with 236

tissue-conditioning material supports the: use of :hi~ material as a functional impression material.‘-‘ Starckr et al.‘” found that the optimal working properties :I! tissue-conditioning materials develop within 1.5 ii, -: i: minutes, during which time the patient was asked 10 speak or read loudly. This functional time period might help orient the denture to the underlying supporting structures. In addition, the lesser displacement caused with the light-bodied polysulfide may he attributed !a) the physical properties of this material, which is
CONCLUSIONS

The contourmeter was used to determine quantitatively the denture displacements caused by various impression materials and techniques during the relining of a maxillary denture. This study indicated the following conclusions. 1. Tissue-conditioning material used with closedmouth impression technique or light-bodied polysulfide used with either open- or closed-mouth technique caused the least denture displacement in the three dimensions when compared with regular-bodied polysulfide or zinc oxide and eugenol impression materials. 2. Comparing the same impression materials used with either open- or closed-mouth technique showed no significant difference in maxillary denture displacements. 3. A relined complete denture should be remounted on the articulator and the occlusion refined to eliminate occlusal mismatches resulting from three-dimensional denture displacements during relining.

DISPLACEMENT

IN RELINE

IMPRESSIONS

REFERENCES I.

17.

Oslrem

C I‘: Relining

11:x4,

iO(ll.

complete

dentures.

J PROSTHET

DENT

IX.

(:haae WVi: ;1daplation of rubber base impression mawrials to rrmovable denture prosthesis. J PROWHET DEXT 10~1043, 1960. l‘uckrr K11 Rrlining complete dentures with the use of a fuwtionat Impression. J PROWHET DENT 16:1054, 1966. Bowman JF, Javid NS: Relining and rebasing techniques. Dent Clin North Am 21:369, 1977 Lt’inklcr S: EssenGals of Complete Denture Prosrhodontics, ed I. I’hiiadclphla, 1979. WB Saunders Co, p 403. I lxw=n NI;, R&sing and relining complete denrures: A terhnique. I)etlt Ctln North Am 8:693. 1961. Feldman LE. Morrow KM, Jameson WS: Relining complete denturfs with an oral cure silicone elastomer and a duplicaLe denture. J PROS.I~X DEN I 23~287, 1970. Sharry JJ: Complete Denture Prosthodontics, ed 3. New York, 1974, Mc(;raw-Hill Book Co, p 294. Gillis RR A relinmg technique for mandibular dentures. J PRfhTllt.l. kY’I’ 10:40i, 1960. Christensrn RT. Relining techniques for complew dentures. J

2.

3.

4. 5. 6. 7.

8. 0. IO.

PROSTIIW

1 I.

DENT

26:373,

Ii. 14.

PROSTIL~,T

IS.

11~~

1:244.

20. 21. 22.

23. 24. 25. 26

27.

197 1.

Jordan I~(;: Relining rhe complete maxillary denture. J PROSIMET 1)t.N’:’ 28:637, 1972. Nagle RJ, Sears VII: Denture Prosthetics, ed 2. St. Louis, 1962, The CX’ Rio&y Co, p 442. Shalter FW, Filler WII. Relining complete dentures with mlnimal owlusal errors. J PKOSTHET DENT 25:366, 1971. Terrell WHRelinrs. rehases or transfers and repairs. J

12.

I9

Bowher CO: Swrnson’s Complete 1)enruxs. wl 5. Sl. Louis, 1964, The (:V Mosby Co, p 210. Shannon JL. Use of the remount jig as an aid in relinin! upper dentures. J PROS~.HE.I‘ DENT 34~393. 1975. Bushman J: Relining full upper and tower dentures. J PKOSTII~.I DEW 2:703, 1952. Bowher CO, The relining of completr dmrures. J PKOS.I.HI:.I. DEXL. 30:521, 1973 IIardy I: Rrbasing rhe maxillary denture. Dent 1)igw 55:23. 1949. Srnlth DE. Lord JL. Bolender C:L: (:ompletc demure relinea with autopolymeri,Gng acrylic resin processed in waler under air pressure. J PROWEI. DENT 18:103, 1967. Lyrle RI!. ‘I’hr managemem of abuse 01 oral Gssurs in comple[c denture ins[ruction. J PROSTHF,T DEW 7:X7, 1957. Chase WFl’: Tissue conditioning utilizing dynamic adap~i\t SIWSS. .J PKowler I>Fxr 11:804, 1961 Wilson HJ, Romlin HR. Osborne J: Tissue wndi~ioners and fun( 11onA inlpres\ion mCilcri;d~. t$r I)enl ,J 121:9, 1966 Si,\rc,kc 1,: ,JI ( Xlarcrof~ KR, Fisher I<. ~wcrnry i1 ‘I‘ l’t1y~ic~;~l propel‘~ics 01 liwit. conditioning mCllcri.ll ‘1, ubrd for functional imprrssions.,J ~‘KOl~lItl~ I)m I’ 27: I I I ( IO??. Ryge G, Fairhuw CW: The c’on~ourmewr: An apparxus for comparison of mucosal surface c’onwur of imprrswns. models and denLure\. ,J PROYTFI~.T DENI. Y:O?6, 105’).

1951.

Griger IXK Restoring health and comfort of tissues under dentures. J PKOS~.III;I. DENY. 1l:Rf 6, 1961. Griger ECK: A relining wzhnique in activated acrylic resin for romplele drnluws. Dent Clin North ;2m 1964. p 705.

16.

Submucosal nodular denture wearers

chondrometaplasia

G. E. Lello, B.D.S., F.D.S.R.C.S., L.R.C.P., M.R.C.S., M.B.Ch.B.,* University

of Zurich,

Department

of Maxillo-facial

A

**Private THE

dozens

JOURNAL

Surgery

Pathology. OF PROSTHETIC

DENTISTRY

and M. Makek,

M.D.**

Surgery, and Institute for Pathology, Zurich, Switzerland

pproximately 25% of denture wearers incur denture-induced oral pathologic changes;lm3 one of the commonest is fibroma formation.‘-’ These fibromata occur predominantly in the region of the anterior maxillary residual alveolar ridge in the form of flabby ridges, or parallel to the edgesof poorly fitting dentures. Although much has beenwritten about the morphology of denture

*Senior Specialisl, Maxilto-facial

in

fibromata,‘,‘,‘, ’ little has been said about the unusual metaplastic changesthat may occur within them. For this reason, all specimensof anterior maxillary denture fibromata received by the Pathology Institute of the University of Zurich between 1971 and 1979 were investigated for signsof metaplastic alteration. MATERIAL

AND METHODS

All oral mucosal biopsies of the anterior maxillary region diagnosed as fibromata, prosthesis fibromata, fibromatous hyperplasia, or fibrosis by the Pathology 237