Community Dent Oral Epidemiol 1997: 25: 160-4Printed in Denmark . All rights reserved

Copyright © Munksgaard 1997

Communify Dentistryand Oral Epidemiology

ISSN 0301-5661

Validation of the Dentai Fear Scaieand tine Dentai Beiief Survey in aNorwegian sampie

Gerd Kvaie\ Einar Berg^,Casper Meyer Nilsen\Magne Raadai^,Geir Hostmark Nielsen'',Tom Backer Johnsen'' andBj0rn Wormnes^'Department of Clinical Psychology, ^Departmentof Prosthodontics, ^Department of Pedodontics,and "Psychometrics Unit, tJniversity of Bergen,Norway

Kvale G, Berg E, Nilsen CM, Raadal M, Nielsen GH, .lohnsen TB, Wormnes B:Validation of the Dental Fear Scale and the Dental Belief Survey in a Norwegiansample. Community Dent Oral Epidemiol 1997; 25; 160-4. © Munksgaard, 1997

Abstract - The aim of this study was to validate the Kleinknecht's Dental FearScale and the Getz's Dental Belief Survey in a Norwegian sample by 1) testingtheir ability to discriminate between fearful («=151) and regular (rt=160) pa-tients, and 2) correlating them. Both instruments were highly reliable (Cron-bach's alpha >0.90). Between 8\% and 95% of the fearful and regular patientswere correctly assigned to their appropriate groups with both instruments. Itmay thus be concluded that both instruments arc valid. Also, the correlationbetween the instruments was 0.68, indicating that they to a large extent seem tomeasure the same concept. The most important predictor items for both instru-ments were related to avoidance of dental treatment.

Key words: DBS; dental fear; DFS: validation

Gerd Kvale, University of Bergen, Departmentof Clinicai Psychology, Christiesgt, 12,N-50t5 Bergen, NorwayTel: +47-55 58 88 85Fax: +47-55 58 98 77E-mail: gerd.kvalefri'psych,uib.no

Accepted for publication 1 August 1996

Dental fear typically leads to delay inthe seeking of dental treatment or theavoidance of necessary dental care al-together. In addition to being an oralhealth care problem, dental fear oftenleads to psychosocial problems and re-duced quality of life (1, 2). The preva-lence of extreme dental fear or odonto-phobia is comtnonly estimated to be 5"Ato 10%. of the adult population (3, 4).

Kleinknecht's Dental Fear Scale(DFS) (5) and Getz's Dental Belief Sur-vey (DBS) (6) are two instruments devel-oped in the United States to assess den-tal, fear. The DFS records behavioral,physiological and cognitive self-reportson specific procedures of dental treat-ment (e.g., making an appointment, see-ing the needle, drilling, rapid heart rate),while the DBS questionnaire mainly as-sesses patients' attitudes to the way den-tists deliver dental care (e.g., the extentto which they feel that dentists are rush-ing, are not really listening to the patient.

are putting the patients down). The DFShas been widely used to measure aspectsof dental fear, and a number of studieshave documented acceptable reliabilityand validity of the instrument (7). De-spite the DBS being a more recent con-struction, the reliability and validity ofthis instrument have also been reportedto be satisfactory (8).

The validity of a given psychometricinstrument may be assessed in variousways. One common strategy is to test agiven instrument's power to assign ref-erence and control individuals to thecorrect group (9). A second strategy isto compare two tests aimed at measur-ing basically the same concept. The va-lidity in the latter case is indicated bythe correlation between the instruments(7). In the current study, both these pro-cedures were employed. Although notpresently used, validity may also be as-sessed by intervention studies, whereone expects the scores of self-referred

fearful subjects to decrease as a resultof the intervention (7).

Employing a self-referred sample ofdentally fearful individuals tends to ex-clude the most fearful ones (e.g., per-sons not seeking treatment for theirdental fear). Tests of validity based onsuch a sample will therefore tend to beconservative. In consequence, our strat-egy may be regarded as a first step tovalidating the instruments.

The original versions of both instru-ments were formulated in English andvalidated in a North American sample.Cultural, linguistic or other variablesmay possibly have an effect on the reli-ability and validity of such scales. Ac-cordingly, they should be revalidated todocument their usefulness in a new con-text.

The DFS and the DBS have beenused in Scandinavia for several years(10-13). In terms of validation theyhave been used in intervention studies

Detttal fear and denial belief sttrvey 161

(11, 14, 15). However, to our knowl-edge, neither their power to discrimi-nate between fearful patients and regu-lar seekers of dental care, nor the corre-lation between them has been analyzedin a Scandinavian population.

The general aim of this study was tovalidate the DFS and the DBS in aNorwegian sample. Specifically, the cur-rent study addressed the following top-ics; 1) the efficacy of the DFS and theDBS in terms of discriminating betweenpatients who regard themselves as den-tally fearful and patients who regularlyseek dental treatment; and 2) the extentto which the two scales measure basical-ly the same concept, i.e., correlate witheach other.

MethodsThe fear group

The fear group consisted of a total of151 patients, 62 males and 89 females.This included all the patients who ap-plied for treatment at a university clinicspecializing in dental fear (Centre forOdontophobia, University of Bergen,Norway) and who also attended theirfirst regular appointment during the

period November 1992 through June1994. All the data were collected priorto any dental treatment.

The reference group

The reference group consisted of 160 in-dividuals, 41 males and 98 females.These were selected among the patientsof general dental practitioners. The in-clusion criteria were; 1) that they hadregular dental treatment; and 2) thatthey volunteered to participate in thestudy.

Instruments

The DFS (5) and the DBS (6) wereused. The DFS contains 20 items withscore levels from 5 (highest fear) to 1(lowest fear). The instrument's items re-late to behavioral reports (patterns ofappointment making and keeping),physiologic reports (heart rate, breath-ing, sweating, etc.) and cognitive reportsof anxiety during a series of consecu-tive, typical events that occur at thedentist, such as waiting in the waitingroom, being seated in the dental chair,seeing and feeling the needle, and hear-ing and feeling the drill (16, 17).

The DBS contains 15 items, withscores from 1 (highly positive beliefs) to5 (highly negative beliefs) for each ques-tion.

All measuring instruments were di-rect translations into Norwegian fromthe original ones.

Procedures

Both groups completed the DFS andthe DBS immediately on arrival at theclinic. The reference group had theirdental treatment immediately thereaf-ter, while the fear group had been in-formed that they were merely scheduledto meet the dentist for a diagnostic in-terview.

Subjects in the reference group wereasked to complete the questionnairesand return them in the stamped enve-lopes which were provided. In additionto completing the questionnaires, thepatients were asked to provide informa-tion about age and gender.

Statistical methods

Age distributions were analyzed forgroup differenees by means of two-

Table 1. Mean DFS item scores for the fear group and the referenee group

Items Mean

4.283.31

4.272.953.613.063.79

3.443.804.134.373.763.833.783.664.054.204.073.464.44

Fear group(;i=151)

SD

1.001.39

0.801.211.041.220.95

1.050.840.850.771.060.951.231.301.020.991.031.170.77

Rank

318

420151911

171062

139

1214857

16

1

Mean

2.041.39

3.111.712.131.542.51

1.772.072.352.612.121.982.452.442.572.672.752.212.54

Reference group(/;=160)

SD

1.400.91

1.120.981.211.001.29

.14

.24

.32

.28

.28

.24

.341.211.351.371.301.221.32

Rank

1520

11812197

1714104

131689532

166

1. Appointments put off due to dental fear2. Appointments eanceled due to dental fear

When having dental work done:3. Muscles tense4. Breathing rate increases5. Perspiration6. Nausea7. Heart beat increases

Rating of fear when:8. Making appointment9. Approaching dentist's office

10. Sitting in waiting room11. Seated in dental ehair12. Smelling dentist's office13. Seeing dentist14. Seeing anaesthetic needle15. Feeling needle injeeted16. Seeing drill17. Hearing drill18. Feeling vihrations of drill19. Having teeth cleaned20. Overall rating, fear of dental treatment

* Abbreviated item texts. For eomplele texts, see KuiiNKNECirr & BURNSTIIIN (5).

162 KVALE ET AL.

Table 2. Mean DBS item scores for the fear group and the reference group

Items*

Fear group Reference group(/(=160)

Mean

3.043,55

3,013,093,033,352.461,793.302.072,712,893.283.023.96

SD

.171.34

.42

.43

.48

.49

.45

.26

.48

.41

.53

.50

.62

.62

.49

Rank

72

10683

13154

141211591

Mean

1.961.85

1.661.391.572.041.541.151.611.171.621.532.461.831.73

SD

1.201.20

1.110.891.051.421.030.571.060.531.081.031.581.361.27

Rank

34

713102

11159

148

12156

1. Dentists don't like requests2. Dentists don't have enough time

When having dental work done;3. No clear explanations4. Dentists don't really listen5. Do what they want, no matter what6. Make tne feel guilty7. Not sure fo believe what dentist says8. Say things to try and fool me9. Don't take my worries seriously

10. Dentists make light of my fears11. Worry if dentists arc technically competent12. Don't think the dentist will stop if if hurfs13. Don't feel 1 can stop for a rest14. Don't feel comforfahle asking questions15. Thought of hearing news keeps me avoiding treatment

Abbreviated item texts. For cotnplcfe texts, see MtLGROM et at. (6).

tailed t-tests for independent satnples.Sex distribution differences were eval-uated by means of chi-sciuare tests.

Reliability assessments for the instru-ments were based on the average inter-eorrelation of the items within eaehscale (Cronbach's alpha).

The validity of the instruments wascomputed by point biserial correlationsbetween group membership atid totalscore on a given scale. In addition,significant group differences for demo-graphic variables were included as cova-riates in the correlational analyses.Also, discriminant analyses were con-ducted separately for each instrutnentto predict group membership on the ba-sis of the total seores.

To identify whieh itetns on eachscale discriminated most clearly be-tween the fear group and the referencegroup, stepwise multiple regressionanalyses were conducted separately foreaeh instrument. F-to enter was 3.84,and F-to remove was 2.71 (default val-ues of the statistical program SPSS)(18). Also, in order to identify whichitems contributed least to the diserimi-nation of the groups, multiple regres-sion analyses were conducted. Itemswith a beta value below 0.05 were in-cluded in the presentation. This cut-offwas set arbitrarily.

Correlations between the instru-ments were investigated by computingthe Pearson product-moment correla-

tion. All signifieanee levels were set at0.05.

ResultsDental avoidance behavior in the feargroup

The fear group had on average avoideddental treatment for a mean of 8 years,ranging from less than 1 year to 58years. Twelve subjeets in the fear grouphad never completed dental treatment.

Age and sex differences between thegroups

Information on sex and age was missingfor 21 and 27 subjeets respeetively inthe reference group. There were signifi-eantly more men in the reference groupcompared with the fear group, %- (I, « =290)=4.23, P<0.05.

Mean age for the referenee group was40.9 years (SD=13.11), and for the feargroup 34.0 years (SD= 11.05). Thisgroup difference was highly signifieant,(t (282)=4.86,

Reliability of the instrunnents

Fstitnatcs of the reliability, based onCronbach's alpha, showed that both in-struments were highly reliable; DFS(« = 300), a=0,97, and DBS («=305),a=0.91.

Validity of the instruments

DESThe mean DFS score for the fear group(«=156) was 76.3 (SD=11.2 ), and forthe reference group (/7=154) the meanscore was 44.6 (SD=19.6). The groupdifferenee was highly significant; rph(298)=0.70, P<0,001. Entering age as acovariate, the difference remainedhighly significant; /'pb (268) = 0.66,/'<0.001. Also, when entering sex as acovariate, the difference remained signi-fieant, r-pb (275)=0.64, P<0.001. MeanDFS item scores for the two groups areshown in Table 1.

The diseriminant analyses of theDFS items showed that 85.7% («=154)of the reference group were assigned tothe correct group. In the fear group,93.8"/;i («=146) of the subjects were cor-rectly assigned.

DBSThe fear group (/i=148) had a meanDBS score of 44.6 (SD=12.6). Thecorresponding mean seore for the refer-ence group (n= 157) was 25.2 (SD = 9.7).This group difference was highly signi-ficant; /'pb (303)=0.66, 7'<0.001, and itremained highly signifieant after agehad been entered as a covariate rpb(273)=0,62, P<0.001. It also remainedhighly significant after sex had been en-tered as a covariate, rpb (274)=0.71,P<0.001. Mean itetn seores on the DBS

Dental fear and dental belief survey 163

Table 3. Stepwise regression analysis showing best single items differentiating between groupson the DFS

Enteredin step # Item # Item text* Statistic

1 Appointments put off due to dental fear13 Seeing dentist2 Appointtnent canceled due to dental fear

20 Overall rating, fear of dental treattnent18 Feeling vibrations of drill

R^ (l,298) = 0.47**R- (2,297)=0.53**R- (3,296) = 0.56**R- (4,295)=0.57**R- (5,294) = 0.58**

* Abbreviated item texts. For complete texts, see KLHINKNECHT & BuRNSTEtN (5).** P<0.00\.

Table 4. Stepwise regression analysis showing best single items differentiating between groupson the DBS

Enteredin step # Item # Item text* Statistic

1 15 Thought of hearing news keeps me avoiding /^-(1,303)=0.39**treatment

2 4 Dentists don't really listen R- (2.303)=0.52**3 2 Dentists don't have enough time R^ {3,30\)=O.5O***4 9 Don't take my worries seriously R^ •" ^tst^\^<^ ^i ***

* Abbreviated item texts. For complete texts, see MILGROM et at. (6).

*** P<0.01.

for the two groups are shown in Table2

The discriminant analyses of theDBS items showed that 87.4% (;(=157)of the reference patients were assignedto the correct group, on the basis of all15 items. In the fear group, 81.1% (n =148) of the subjects were correctly as-signed.

Single items differentiating betweengroups

DFSUsing "group" as the dependent vari-able, the multiple regression analysesindicated that the total of 20 items ex-plained 60% of the variance; R2 (20,279)=0.60. The stepwise regressionanalyses for DFS identified five items asthe best predictors (Table 3).

The multiple regression analyses in-dicated that five items did not reach abeta value of 0.05 or more. In beta-ranked order these were items #4, 9, 19,16 and 12 (for item texts, see Table 1).

DBSUsing "group" as the dependent vari-able, the multiple regression analysesshowed that the total of 15 items ex-plained more than 50% of the variance;

R2 (15, 289) = 0.52, P<Q.OO\. The step-wise regression analyses for the DBSentered four items (Table 4).

The multiple regression analyses in-dicated that 9 out of 15 items did notreach beta values of 0.05 or more. Theseare presented in beta-ranked order;items #8, 3, 6, 7, 10, 11,1,5 and 12 (foritem texts, see Table 2).

Correlations between the instruments

The DFS and the DBS were signifi-cantly positively correlated; r (295) =0.68, P<0.001.

DiscussionDFS

With regard to the DFS, nearly 95"A< ofthe fear patients were assigned to thecorrect group, on the basis of the totali-ty of single item scores. In the referencegroup the analogous assignment wasnearly 86%). As an indication of validitythis result may be considered highly sat-isfactory. Only future studies recordingtreatment compliance of the referencegroup may determine to what extentthe nearly 15% of the subjects in the ref-erence group who were incorrectly as-signed to the fear group consist of pa-

tients who only partially comply withdental treatment, or are "haters butgoers" (6).

Mean DFS score for the dentallyfearful was 76.3. Cotnparable meanscore on the DFS for odontophobics ina Danish sample was 75.8 before treat-ment and 31.3 after treatment (15). Thelatter figure may appear somewhatlower than the corresponding score forthe reference group in the current study(44.6). Normative Scandinavian scoreson the DFS are not available.

The stepwise regression analyses in-dicated that the single items focusing onthe avoidance behaviour (items #1 and2, Table 3) seem to be highly relevant interms of discriminating betweengroups; the former explaining nearly50% of the variance. Also, a more glob-al assessment of dental fear (item #20)was significant.

Only two of the items related to feel-ings and cognitions in the dental situa-tion were important in this context(itetiis #13 and 18, Table 3). The con-tents of these items are the degree offear, anxiety or unpleasantness when"seeing the dentist walk in" and "feel-ing the vibrations of the drill", respec-tively. This may indicate that situationsthat are considered slightly fear or anxi-ety provoking for subjects who regular-ly seek dental treatment are often re-garded to be of great importance by thefearful subjects.

DBS

More than 80"/> of the members of eachgroup were correctly assigned with re-spect to group membership on the basisof the totality of single item scores. Asa validity indicator this overall resultmay be considered satisfactory. Never-theless, nearly 20'̂ ) of the fearful groupand 15'/o of the reference group were as-signed to incorrect groups.

Mean DBS score for the fearful pa-tients was 44.6. This appears to be inagreement with American and Scandi-navian scores which range between 42and 50 (8, 13-15), and decrease to be-tween 24 and 17 after treatment fordental fear (8, 14, 15). Normative Scan-dinavian mean scores for regular seek-ers of dental care are not available.However, a Swedish study reports amean DBS score of approximately 30for patients attending an emergency

164 KVALE ET AL.

clinic (13). This result appears to besotnewhat higher than the current meanscore of 25.2 for the referenee patients,most likely related to differences in theselection of the groups. The present re-sult is also equivalent to the corre-sponding Ameriean figure (24) for fear-ful patients after treattnent for dentalfear (8).

The stepwise multiple regressionanalyses indieated that the single itetnwith the greatest power to discriminatebetween tbe groups was the question re-lated to the subjects' fear of "bad news"(item #15, Table 4), which accountedfor nearly 40% of the explained vari-ance. This item may be regarded as dif-ferent from the others, in the setise thatit is tnore directly related to one of themain consequences of dental avoidance,namely poor dental health. In a previ-ous study (13) it was also shown thatthis item distinguished clearly betweena group of self-referred patients and pa-tients seeking treatment in an emer-gency elinie. Also, item #15 was rankedas nutnber one in a sample of 80 pa-tients diagnosed as odontophobic ae-cording to DSM III-R criteria (14). Fordiagnostic purposes it thus seems itn-portant to include item #15 in the DBS,rather than employing the 14-item ver-sion (19). The other three items of someimportance in this context were relatedto the feeling that dentists do not listen,that dentists hurry, and that dentists donot take the patients' worries and fearsseriously (items #4, 2 and 9, Table 4).

The fact that 9 items out of 15 didnot reach beta-values of 0.05 or above(stepwise regression) indicates that den-tally fearful patients do not neeessarilyexpress signifieantly more negative atti-tudes to dentists than those regularlyseeking dental treatment. This findingmight appear to be somewhat in con-flict with previous Seandinavian results(13). However, previous Scandinavianstudies on the DBS have neither em-ployed regular seekers of dental treat-ment as a reference group, nor madestatistical evaluations on the indepen-dent contribution to the explained vari-ance of single items.

In a future study it would be inter-esting to explore whether dental fearpatients with a low DBS score to a lessextent tend to attribute their dental fearto specific negative experiences withdental treatment, and to a greater ex-

tent make internal attribution of theirdental fear, compared to those with ahigh DBS seore. It should, however, benoted that patients included in the pres-ent study were self-referred, and that noformal differential diagnosis regardingtheir dental fear was made. It has beensuggested that dental fear patients withspecific phobia tend to have lower DBSscores, while patients characterized bysocial phobia tend to have higher DBSscores (20), Other recent studies havealso indicated that more attentionshould be given to the differential diag-nostic aspects of dental fear (14, 21).

Correlation between the DBS and the DFS

The significant positive eorrelation ofnearly 0.7 between the instruments re-fieets that both the DFS and the DBSto a certain extent measure denial fear,which is also clearly demonstrated intheir power to discriminate between thetwo groups. It might be argued, how-ever, that the positive correlation alsorefiects that attitudes towards dentaltreatment and dentists on the one hand,and subjective behaviors, feelings andcognitions related to the dental situa-tion on the other hand, to some extentare not entirely overlapping concepts.

In conclusion, the present study hasconfirmed the validity of using DFSand DBS in a Norwegian sample. Bothare able to discriminate between thegroups and they are highly correlated.Furthermore, it appears that the abilityof both instruments to discriminate be-tween the groups is mainly related toitems concerned with avoidance be-havior.

References

1. BERGGREN U. Dental fear and avoid-ance; a study of etiology, consequencesand treatment [dissertation]. Gothen-burg, Sweden; University of Gothen-burg, 1984.

2. BERGGREN U. Psychosocial effects asso-ciated with denfai fear in adult dentalpatients with avoidance behaviours.Psyctiot Heatth 1993; 5.- 185-96.

3. MOORE R , BIRN H , KIRKEGAARD E,BR0DSGAARD I, ScHEUTZ F. Prevalenceand characteristics of dental anxiety inDanish adults. Community Dent OratEpidemiot 1993; 21: 292-6.

4. FtSET L, MILGROM P, WEINSTEIN P, MEL-NICK S. Common fears and their rela-tionship to dental fear and utilization ofthe dentist. Anestli Proi; 1989; 36: 258-64.

5. KLEtNKNHCIIT RA, Bl-RNSTEIN DA. Theassessment of dental fear. Behav Ther1978; 9: 626-34.

6. MILGROM P, WHINSTEIN P, KLEINKNECHTR, GETZ T. Treating fearful patients: actinicat handbook. Reston; Reston Pub-lishing Company, 1985.

7. SHUURS AHB, HOOGSTRATEN J. Apprais-al of denfai anxiety and fear question-naires; a review. Communitv Dent OralEpidemiot 1993; 21: 329-39."

8. SMriH T, GETZ T, MILGROM P, WEINSTEINP. Evaluation of treatment at a dentalfears research clinic. Spec Care Dentist1987; 7: 130-4.

9. STOUTt̂ ARD ME, MELLENDERGH GJ,HOOGSTRATEN J. Assessment of dentalanxiety; a facet approach. Anxiety StressCoping 1993; 6: 89-105.

10. MOORE R. Dental fear treatment; com-parison of a video trainitig procedureand clinical rehearsals. Scand J Dent Res1991; 99: 229-35.

11. MOORE R, BERGGREN U, CARLSSON S,BRBDSGAARD I. Generalization of effectsof dental fear treatment in a self-referredpopulation of odontophobics. J BehavTher Fxper Psychiatry 1991; 4: 243-53.

12. JOHANSSON P, BERGGREN U. Assessmentof dental fear. A comparison of two psy-chometric instruments. Acta OdontolScuiid 1992; 50: 43-9.

13. JOHANSSON P, BERGGREN U, HAKt;ni-RGM, HtRSCH JM. Measures of dental be-liefs and attitudes; their relationshipswith measures of fear. Communitv DentHeatth 1992; 10: 31-9.

14. MOORE R , BRODSGAARD I, BtRN H.Manifestations, acquisition and diagnos-tie categories of dental fear in a self-re-ferred population. Behav Res Ttier 1991;29: 51-9.

15. MOORE R, BERGGREN U, CARLSSON S G .Reliability and clinieal usefulness of psy-chometric measures in a self-referredpopulation of odontophobics. Com-munitv Dent Orat Epidemiot 1991; 19-347-51.

16. KLEINKNECHT RA, MCGLYNN F D ,TMORNDIKE RM, HARKAVY J. Factoranalysis of fhe dental fear survey withcross-validation. J Am Dent Assoc 1984;108: 59-61.

17. MCGLYNN FD, McNetL DW, GALLAGH-ER SL, VRANA S. Factor structure, sta-bility, and internal consistency of thedental fear survey Behav Assess 1987; 9:51-66.

18. SPSS [cotnputer software] Chicago, II,SPSS Inc. 1993.

19. KUNZELMAN KH, DuNNtNGER P. Dentalfear and pain; effect on patient's percep-tion of the dentist. Communitv Dent OratEpidemiot 1990; 18: 264-6.

20. MooRii R, BR0DSGAAt<D I. Differentialdiagnosis of odontophobic patientsusing the DSM-IV. Eur ,1 Oral Sci 1995;103: 121-6.

21. HAKEBERG M , GUSTAESSON JE, BERG-GREN U, CARLSSON SG. Multivariateanalysis of fears in dental phobic pa-tients according fo a reduced FSS-IIscale. Eur J Oral Sci 1995; 103: 339-44.