Clinical Evaluation of Restored Maxillary Incisors_ Veneers Vs

10.14219/jada.archive.1995.00811995;126(11):1523-1529JADA

DJ Pippin, JM Mixson and AP Soldan-Elsincisors: veneers vs. PFM crownsClinical evaluation of restored maxillary

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ARTICLE 1

CLINICAL EVALVAJION OF RESIORED MAXILLADY INCISORS:VENEERS VS. PFM CROWNSDAVID J. PIPPIN, D.D.S., M.S.; JAMES M. MIXSON, D.D.S., M.S.;ANTON P. SOLDAN-ELS, D.D.S.

This cross-sectional study com-

pared the periodontal health and

clinical acceptability of maxillaryincisors restored with porcelainveneers vs. porcelain-fused-to-metal crowns. The authors eval-

uated 60 patients, a total of 120

restorations, in groups accord-

ing to the age of the restorations

(zero to 60 months). Margins ofveneers were generally more

supragingival with less gingivalinflammation. All veneers were

clinically acceptable, while 5percent of PFMs failed because

of secondary caries.

Gentists historically have used porcelain-fused-to-metal crownsfor the esthetic restoration of maxillary incisors. Although this typeof restoration has served us well, PFM preparations do have somedrawbacks. For example, preparation for PFM crowns is not conser-vative of tooth structure. Also, the margins of these restorationsoften are placed below the gingival margin. Dentists have knownfor some time that such placement of restoration margins is detri-mental to gingival health.`4 This is true regardless of the materialused, although differences exist for various materials.4

Supragingival margin placement, by contrast, offers greater ac-cess for plaque control and maintenance procedures and thus, re-sults in fewer deleterious effects on gingival health.15 Despite theclinical benefits of supragingival placement, however, patients maybalk at visible margins on anterior teeth and may prefer subgingi-val placement.67

Porcelain laminate veneer restorations address some of the limi-tations ofPFM full coverage. For example, veneer restorations re-quire only conservative tooth preparation. Veneer margins can bebonded to enamel to increase retention and decrease microleakage.6Supragingival or equigingival placement8 of the veneer margin mayallow a translucent blending of the tooth and the restoration at themargin of the veneer.6 Despite this final benefit, however, Karlssonand colleagues report that dentists continue to place a significantproportion of veneer margins subgingivally for a variety of reasons.7Anecdotal reports suggest that the potential for less intrusive mar-gin placement when porcelain laminate veneers are used may leadto advantages for the periodontal tissues.69 Acceptance of porcelainlaminate veneers among practitioners is high, with 91 percent in arecent survey rating veneers as an ethical choice for estheticrestorations.10

This clinical study compares, for the first time, parameters ofperiodontal health, restoration integrity and esthetics betweenPFM crowns and porcelain veneer restorations.MATERIALS AND METHODS

This retrospective study is a cross-sectional survey of randomly se-

JADA, Vol. 126, November 1995 1523

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-CINICAL POACTIICE

TABLE I

lected volunteers from the poolof active patients at the

University of Missouri-Kansas

City dental school. The accep-tance rate among those asked to

participate exceeded 90 percent.All participants signed an in-formed consent form approvedby the appropriate InstitutionalReview Board.

To qualify for the study, par-ticipants had to have had thesame type of restoration-ye-

neers or PFM crowns-previ-ously placed on each of twomaxillary incisors during a sin-

gle appointment at the dentalschool. Although we preferredto evaluate restorations on cen-

tral incisors, we did occasionallysubstitute restorations on lat-

eral incisors in the sample.Restorations were placed bypredoctoral dental studentsunder the direct supervision ofdental faculty. All PFM mar-

gins were beveled shoulders.

LABIAL LIN,

PFM crowns were fabricated at

the school and veneers were

fabricated by a local dental lab-

oratory.

We selected 60 patients witha total of 120 restorations to

participate in the study. Halfthe sample had two porcelainlaminate veneer restorations

(Group I) and the others hadtwo PFM crowns (Group II).Group I consisted of 13 men and

17 women ranging in age from18 to 77 years, with an average

age of 36. Group II was com-

posed of 15 men and 15 women,ages 25 to 76 years, with an av-

erage age of 56.

These two groups were then

further divided according to the

age of the restorations:

zero to six months;seven to 24 months;25 to 60 months.

Each subgroup had 10 pa-tients (20 restorations) assignedto it.

We col-

lected a medi-cal history foreach partici-

GQUAL. pant and ex-~~cluded anyone

TOOTRIwho had con-ditions or

habits that

9.53* would ad-

34.05 versely affect

gingival

1.42 health (suchas use of med-

_7__ ications likecyclosporine,

0.17* calcium chan-

0.60 nel blockers,birth control

pi'lls, estrogenor phenytoin;immune sys-

tem dysfunc-tion; recentanti-inflam-

matory thera-

py; chronic illness or infection;diabetes; or tobacco use).

To assess the periodontalhealth and clinical adequacy ofthe restorations, three clini-cians measured various clinical

parameters. Examiners col-

lected clinical measurements at

six sites per tooth (distolabial,labial, mesiolabial, distolingual,lingual, mesiolingual). The clin-icians were calibrated, and theyexamined approximately thesame number of patients ineach subgroup. Interrater

agreement exceeded 85 percent.

Periodontal measurements

included gingival crevicularfluid flow, pocket depth mea-

surement, gingival bleedingindex1' and the Quigley, Hemnand Turesky plaque index.'12 Theexaminers measured gingivalcrevicular fluid flow by placinga filter paper strip 1 millimeterinto the gingival sulcus for 10seconds and discarding it, then

1524 JADA. Vol. 126. November 1995

INTER-MID- INTER-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Gingival c--re-viculanrfluxid

Vexieer 17.25* 1 07'16.40*PFMA 35.91 22.48 45.62

Veneer- 2.28 1.50 2.12PFM 2.52 1.67 2.48

Venaeer 0.4l* 0.22 0Q39*PFM 0.63 0.25 0.77

Veneer ~~~0.93 0.82 1L.89*PFM ~~~~~0.89 0.75 0.48

*Difference between pairs is statistically significant, P

CLINICAL PRACTICEm

Figure 1. Mean gingival crevicular fluid flow scores on the labial as-pects of maxillary incisors restored with veneer or PFM crowns. MOmarginP2 mm above the gingiva; M1, margin-c2 mm above the gingiva;M2, margin even with the gingiva; M3, margin extends beneath thegingiva.

TABLE 2

0123

0.020.655.623.8

0.010.027.862.2

inserting a second, fresh stripfor 30 seconds and immediatelymeasuring the gingival crevicu-lar fluid in a Periotron 2000(Pro-Flow, Inc.). GCF scoresfrom zero to 20 indicate relativehealth, those 20 to 40 indicatemoderate gingivitis and scoresgreater than 40 indicate overtgingivitis.

Clinicians used a UNC (Hu-Friedy) periodontal probe

91.11.76.11.1

1.718.331.148.9

graded in 1-mm increments tomeasure pocket depths.

The examiners scored thegingival bleeding index afterprobing using 0 to indicate nobleeding; 1 to indicate bleedingat a single point; 2 to indicate aline of bleeding; and 3 to indi-cate profuse bleeding.

After staining the teeth, theclinicians rated the presence ofplaque on a scale of zero

through five (0, no plaque and5, abundant plaque coveringtwo-thirds of the area or site).Facial and lingual aspects wereconsidered separately since thelingual aspect of the veneergroup consisted of virtually un-restored tooth surfaces, particu-larly at the gingival margin.

Restorative assessment in-cluded the margin index ofSilness, which scores the mar-gin position relative to the gin-giva on a scale of zero throughthree. Examiners scored cariesas present or absent. They as-sessed margin integrity and therestoration's surface, color andanatomic form according to themodified Ryge criteria for clini-cal assessment.'3 Only the labialsurfaces of each group werecompared for these threerestorative indexes. Each pa-tient also completed a surveynoting satisfaction with esthet-ics and comfort of the restora-tion.We compared the parametric

data between the groups usingindependent t-tests and com-pared the ordinal data betweengroups using Kruskal-Wallistests. To evaluate the changesacross time within the twogroups by subgroup, we usedanalysis of variance.RESULTS

We evaluated a total of 120restorations, 60 veneers and 60PFMs. For the veneers, themean time in service for eachsubgroup was- zero to six months, 2.6months;- seven to 24 months, 13.9months;-25 to 60 months, 41.8 months.

For PFMs, the mean time inservice for each subgroup was- zero to six months, 2.5months;


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Figure z. Mean gingival bleeodng Inaex scores on tne labial aspects oTmaxillary incisors restored with veneer or PFM crowns. MO, marginx2mm above the gingiva; M1, marginc2 mm above the gingiva; M2, mar-gin even with the gingiva; M3, margin extends beneath the gingiva.

- seven to 24 months, 15.9months;-25 to 60 months, 43.2months.GCF increased as margins

were placed closer to and belowthe gingiva (Figure 1). Therewas a significant difference be-tween the GCF scores of pa-tients with veneers and thosewith PFMs (P

CLINICAL PRACTICEI

Figure 3. Percentage of participants who rated the appearance of theirrestorations as "excellent."

There was no difference withineach group with the passage oftime.

There were no differences inscores for anatomic form be-tween groups for each time peri-od or within each group acrosstime. Examiners did not detectany fractures in the veneer orPFM group for any time period.

Margin integrity was not sta-tistically dif-ferent betweenveneers andPFMs. One

Dr. Pippin Is an as-sociate professor,Department ofPeriodontics, Schoolof Dentistry, Uni-versity of Missouri-Kansas City, 650 E.25th St., KansasCity, Mo. 64108.Addres reprint re-quests to Dr. Pippin.

ftt_

Dr. Mixson Is an as-sociate professor,Diagnostic Sciences,School of Dentistry,University of Mis-souri-Kansss City.

PFM, rated not acceptable, hadzinc phosphate cement at themargins that required removal.An additional three of the 60PFMs examined had secondarycaries, equal to 5 percent of thetotal. Examiners did not detectany caries on any of the restora-tions in the veneer group.

Patients generally expressedhigh satisfaction with the ap-pearance and comfort of theirrestorations, both veneers andPFMs. No significant differ-

ences were re-ported in the

V comfort of therestorations;

1_0most patientsrated the com-fort level of

Dr. Soidan-Els Is an their restora-associate professor. tions as goodRestorative Den-tistry, School of or excellent.Dentistry, University Although thereof Mlssouri-KansasCity. was no statisti-

cally significant difference inpatient self-ratings concerningthe restorations' appearance,there was a trend for patientswith veneers to be more highlysatisfied than those with PFMsover time (Figure 3). For exam-ple, at 25 to 60 months, 80 per-cent of veneer patients ratedtheir appearance as excellentcompared with 40 percent ofpatients with PFMs.DISCUSSION

Studies show that subgingivalplacement of restoration mar-gins adversely affects gingivalhealth.'4 Examiners oftennoted clinical signs of gingivitisduring this study, especiallywhen margins were subgingi-val. Although they reportedvariation among participants,indexes of inflammation, gingi-val crevicular fluid flow andgingival bleeding index scoressubstantiated this clinical ob-servation. Because neither theGCF nor the gingival bleedingindex scores increased overtime for any given marginindex score, we assume thatthe gingival inflammation ap-peared to establish itself early.Higher scores were seen for theindexes of inflammation as themargin index scores increased,that is, as margin placementmoved closer to and below thegingiva, there was more gin-givitis.

Scores for the clinical indexeswere higher at each marginindex value for PFMs than forveneers. Perhaps the PFM mar-gin was more plaque retentivedue to margin adaptation, ce-ment margin or gap size, or per-haps the PFM margin harboredorganisms that were more viru-lent.14 No correlation betweenany of the indexes and theTuresky plaque index was


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found, in part because thisindex appears to have scored forplaque in the wrong area. Theporcelain surfaces were rela-tively free of plaque andsupragingival plaque scoreswere correspondingly low. Amethod of sampling or scoringthe margin area and its subja-cent tooth surface may havebeen more useful.

There was a notable discrep-ancy in the participants' agesbetween the veneer group (aver-age age of 36 years) and thePFM group (average age of 56years) in this study. The exam-iners adhered to rigorous exclu-sion criteria for any confound-ing variables that could haveadversely affected gingivalhealth. However, disparity inage between groups is a limita-tion of this study. At our school,the younger individuals tendedto have veneer coverage, whileolder individuals may have hadgreater need for full coveragebecause of multiple restora-tions, existing caries or previousendodontic treatment.

There was no evidence of gin-gival recession for veneers orPFMs either clinically or whenthe data were analyzed by sub-group. When compared acrosstime, the margin index scoresshowed no increase for eitherrestoration.

Pocket depths generally wereshallow with a trend for slightlyhigher depths around PFMs.Our data did not indicate thatgingivitis necessarily led to per-iodontal disease. Only a verysmall percentage of either typeof restoration exhibited pocketdepths greater than 3 mm andno readings deeper than 4 mmwere recorded at any site. Itmay be that periodontal diseasetakes longer to establish itselfthan the 60-month limit of our

study or that our sample sizewas not adequate to pick up thesmall percentage of cases thatprogress from gingivitis to peri-odontal disease.

Examiners rated veneers sig-nificantly higher than PFMs inevaluating the quality of sur-face and color. The higherscores may be attributed to sev-eral factors. Since veneers oftenwere placed for esthetic rea-sons, patients with veneers fre-quently had multiple veneers

Subgingival placement ofthe margins ofrestora-tions adversely affectsgingival health, and ve-neers have the potentialfor less intrusive place-ment.

placed on their anterior teeth,influencing a harmonious colormatch. However, the presenta-tion was not always simple. Forthe veneer group, 12 out of 30subjects had four or six anteriorteeth restored with veneers,eight out of 30 subjects hadonly teeth nos. 8 and 9 ve-neered and 10 out of 30 had amix of veneers and PFMs. Forthe PFM group, six out of 30subjects had four or six anteriorteeth restored with PFMs, sixout of 30 had at least one otherPFM placed and 18 out of 30had only teeth nos. 8 and 9 re-stored. When PFMs or veneerspresented as two single restora-tions in the anterior region,there appeared to be more diffi-culty in matching the color ofthe porcelain to the adjacentteeth. In addition, veneers andPFMs were fabricated at sepa-rate laboratories, which mayhave influenced any differences

in porcelain quality. Surfaceroughness of porcelain ap-peared to be caused by inade-quate polishing following chair-side adjustments.

While there was no statisti-cal difference in margin integ-rity between PFMs and veneers,PFM margins appeared to bemore susceptible to secondarydecay (5 percent of the total ex-amined). No carious lesionswere recorded on teeth restoredwith veneers.

Gender was evidently not afactor in this study. No differ-ences could be attributed togender for any index, and nodifferences existed over time asrelated to gender.CONCLUSION

The trend from this study isclear. Subgingival placement ofthe margins of restorations ad-versely affects gingival health,and veneers have the potentialfor less intrusive placement.Additionally, PFMs appear tohave increased deleterious ef-fects on the gingiva with higherscores at each margin indexvalue compared with veneerscores at the same margin indexvalue. PFMs may be more sus-ceptible to secondary caries aswell. While there are clinicalsituations that demand full-cov-erage porcelain restorations,this study suggests that whenteeth are restored for estheticreasons, porcelain veneers arethe restoration of choice.Indeed, participants who hadveneer restorations in thisstudy tended to become morepleased with their appearanceas time passed, while PFM sub-jects became less pleased.Porcelain veneers appear to beclinically acceptable, durablerestorations for maxillary ante-rior teeth. .

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This study was supported by ChameleonDental Products. Instruments were donatedby Hu-Friedy.

1. Silness J. Periodontal conditions in pa-tients treated with dental bridges. II. The in-fluence of full and partial crowns on plaqueaccumulation, development of gingivitis andpocket formation. J Periodont Res 1970;5:219-24.

2. Silness J. Periodontal conditions in pa-tients treated with dental bridges. III. The re-lationship between the location of the crownmargin and the periodontal condition. JPeriodont Res 1970;5:225-9.

3. Valderhaug J, Birkeland JM. Periodontalconditions in patients 5 years following inser-tion of fixed prostheses. J Oral Rehabil1976;3:237-43.

4. Larato DC. Effect of cervical margins ongingiva. J Calif Dent Assoc 1969;45:19-22.

5. Raetzke P. [Reaction of the marginal gin-giva to contact with crown or veneering mate-rials in subjects with excellent oral hygiene.]Dtsch Zahnarztl Z 1985;40:1206-8 (Eng.Abstract).

6. Friedman MJ. The enamel ceramic alter-native: porcelain veneers vs. metal ceramiccrowns. J Calif Dent Assoc 1992;20(8):27-33.

7. Karlsson S, Landahl I, Stegersjo G,Milleding P. A clinical evaluation of ceramiclaminate veneers. Int J Prosthodont1992;5:447-51.

8. de Rouffignac M, de Cooman J. Aestheticall-porcelain anterior restorations. PractPeriodontics Aesthet Dent 1992;4(8):9-13.

9. Cutbirth ST. Restoration of maxillary an-terior teeth using porcelain jacket crowns andporcelain veneers. J Esthet Dent 1992;4(1):1-5.

10. Christensen GJ. How ethical are es-thetic dental procedures? JADA 1994;125(11):1498-502.

11. Muhlemann HR. Psychological andchemical mediators of gingival health. J PrevDent 1977;4(4):6-17.

12. Turesky S, Gilmore ND, Glickman I.Reduced plaque formation by thechloromethyl analogue of victamine C. JPeriodontol 1970;41:41-3.

13. California Dental Association. Qualityevaluation for dental care. Guidelines for theassessment of clinical quality and profes-sional performance. Los Angeles: CaliforniaDental Association; 1977.

14. Lang NP, Kiel RA, Anderhalden K.Clinical and microbiological effects of subgin-gival restorations with overhanging or clini-cally perfect margins. J Clin Periodontol1983;10:563-78.

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Clinical Evaluation of Restored Maxillary Incisors_ Veneers Vs