Restorative treatment thresholds and agreement in treatment decision-making
Elizabeth Jane Kay\ Nigel Michael Nuttali^ and Robin Knili-Jones^ 'Department of Dental Health and 'Dental Health Services Research Llnit, University of Dundee. Dundee and 'Department of Public Health, tjniversity of Glasgow, Glasgow. Scotland
Kay E.I, Nuttail NM, Knill-Jones R: Restotative treatment thresholds and agreement in treattnent tleeision-making. Commtinity Detit Oral Epidemiol 1992; 20: 265-8. Abstract - It has been recognised for many years that treattnent deeision-making among dentists often shows wide variatioti. This study sought to examitie the effect of dentists' stated treatment thresholds as a source of variation between them. Twctity dentists made .^60 treatment decisions about the approxitnal stirfaces of extracted teeth seen in simulated bitewing radiographs. They also stated their personal treatment thresholds, i.e. the depth of lesion which they ititended to restore. One luindred and ninety pairwise comparisons of treatment decisions showed that only lOi'Vu ofthe dentist pairs showed substantial agreement. Dentist pairs who reported that they held the same iiiterveiitive threshold aehieved exactly the same metiti level ol agieenient in treatinent decisioii-tnakiiig as detitist pairs who disagreed about the appropriate threshold lor restorative intervention. The study suggests that restorative thresholds which are reported to be used by dentists may be poorly correlated with the ntiniber of positive treatment ileeisions actually made.
Many investigations have reported that there are elinically important differenees between dentists' interpretations ol diagnostic tests and the treatment deeisions which they subseqtiently make. Variations (I 12) in tieatment planning appear to be due to the cliniciatis' views as to the ability of a lesion to survive a given time period, or to their expectation of progression to pain and/or extraction of the tooth in question {5). Iherelore the thre.shold at which restoration becomes the optimal tteattiieiit decision ought to be related to the clinicians' knowledge of the rate and frequency of progression or regression of lesions (13) or to their view as to the radiographie appearance which represents the presenee of eavitation (14) as it is at this stage that lesion can no longer "regress" (15). It is thus understandable that the treattnetit thtesholds set by itidividual practitioners are not consistent with each other. However, studies which examitie observer variatioti (1-12), particularly those in which the treatment threshold is unequivocally laid down (16-18), suggest that there are further souiees of variation. Two ptocesses niay lead to these variations between clitiicians (10). E'irst, some may hold diffeiing opinions about what coti-
stitutes the optimum point for intervention (19). Secondly elinicians may perceive differetit costs and benelUs to be contingent upon their deeision (.5, 20, 21). NtniALL (10) diffetentiated between these two potential sources of dentists' discrepancies in treatment planning, as judgemental and perceptual variation. These differ in tiatuie from each other, .ludgemeiital variation is likely to stem from a consistent process - two dentists who have differing views about the stage ill the carious process at which a filling is requited (restorative treattnent threshold) will differ in a systetnatie way. A detitist who advocates earlier intervention than a colleague should only disagree about the treatmetit of lesions which he believes have reaehed a stage at whieh a filling is required but whieh his eolleague thinks ate not sufficiently advaticcd to tieed treatment. They will agree on the need to fill lesions which have progressed up to or beyond both their restorative treatment thresholds. Perceptual variation on the other hand was viewed by NtrriAt.t, (10) as stetntning from differing pereeptions of what dental eondition is aetually present. There might be a systematie eletnent in differing perceptions, for example where
Key words: agreement; decision-making; kappa; treatment thresholds E. J, Kay. Dept, of Dental Health, University of Dundee, Dundee. Scotland Accepted for publication 21 November 1991
one dentist always "sees" a cavity as larger than a colleague. However, there is also likely to be a larger non-systematic or randotn element involved, stemming in part from the weighting attached to eorreet and incorreet decisions (21). Several studies have shown that dentists report using differing restorative treatment thresholds {5. 19, 22-24). However, the extent to which these thresholds influenee testorative dental treatment deeisions has not been explored in detail. This study attempted to do so by comparing the restorative tieatment plans made by dentists on the basis of radiographic exatnination. with their views on when is the most appropriate point to intetvene. Materials and methods
Twenty randomly selected general dental practitioners in the City of Glasgow were provided with a list of descriptions of lesions affecting an approximal surfaee in a 16-yr-old who was described as having moderate earies experience and likely to attend the dentist again within a year. Each dentist was asked to indieate the point at which a filling would be required (restorative treatment threshold). The
266
KAY ET AL.
Eig. I. All example of the hitewiiig radiographs u.sed in Uie study.
descriptions used were: 1) The lesion has penetrated up to half of the enamel. 2) The lesion has penetrated into the deeper half of the enamel but has not reached the amelo-dentimal junction. 3) The lesion has reached the amelo-dentimal junction but has not penetrated dentine. 4) The lesion extends into dentine. 5) The lesion extends well into dentine. No dentist used category 1. Three categories were used in the analysis, these being: treatment thresholds Before ADJ (threshold 2 above). At ADJ (threshold 3 above) and Into Dentine (thresholds 4 and 5 above). The dentists were then asked to make restorative treatment decisions on the basis of 30 bitewing radiographs presented in pairs which had been taken of extracted teeth mounted to simulate a real mouth (Fig. I). Every dentist examined the same sets of radiographs to obviate problems of variable density and contrast. Each dentist made treatment deeisions concerning 360 tooth surfaces (12 surfaces per radiograph x 30 radiographs). The dentists were asked to view
the radiographs in the manner which they used in their day to day practice of dentistry. Subsequently the teelh used in the simulated radiographs were serially sectioned and the maximum depth of any approximal lesions rccotded. The criteria used are shown in Table 1. Results
Of the 20 dentists in the study, three stated that they intended to restore all carious lesions which extended beyond hall the thickness ofthe enamel ("Bcjorc ADJ"), eight dentists indicated that any lesions which had reached the amelodentinal junction should be restored ("At ADJ") and nine felt that a lesion should only be treated restoratively when it had penetrated into dentine ("Into Dentine"). Microscopic examination of the teeth which had been tised to simulate the radiographs after sectioning showed that 43 (12%) had dentinal caries and 52
(14'y(i) had lesions restricted to enaniel Further details of the detitists' decisions in relation to lesion depths in this study have been reported elsewhere (21, 24). Fig. 2 shows the number of fillings planned, grouped accotding to the den... tists' reported restoiative treatment thresholds. Paradoxically, one ofthe dentists (nutnber 11) who claimed to intervene at an early stage in the development of caries (i.e. before the AD.I) iilanneci fewest ftllings. The meati number of surfaees which would have been restored Viy those who would fill a lesion prior to its penetiatinglo the ADJ was 21. The mean number of surlaces lestored by those who said they would not fill a lesion until it had penetrated to the AD.I, was 36 and those who said they would wait until a lesion had cntctcd dentine, planned to restore a mean of 25 surlaces. Usitig yi analysis there were no dilferences in the mean nutnber of surfaces filled by the three grottps (P> 0.5). Iti total there were 574 decisiotis to restote tooth surfaces and 6626 that a filling wa.s tiot required If all decisiotis made by a dentist for each individual toolh stirfacc are conipated to all deeisions tnade by other dentists for that surface there are a total of 68400 paited eotnparisons. Overall 62974 (92'!4i) were in agreemetit. The probability that a dentist would agree with a decisioti to fill made by atiother dentist was 0.50. The probability that a dentist would agree with atiother dentist's decision not to fill was 0.96. iMg. 3 detnonstrates that b"/n (11) Q(tlie pairs of dentists obtained only "slight agreetnetit" with each other usintj
70-, 60
Tabel 1. Microscopic critcriji used lo validate dentists" decisions Score
Description
0 1
Sound Lesion confined to outer half of enamel Lesion penetrating the inner hall ol the enamel but not penetrating dentine Lesion into dentine but less than halfway to pulp Lesion into dentine and more than hallway to pulp Restored surface without faults Restored surface with faults Restored surfaee with caries (with or without faults) Missing data
2
4 5 6 7 9
Before ADJ
N
^°^
of
40 ^
Fillings Planned
At ADJ
50
Into Dentine
47
34
34 34 35
22 20 7 100-
a 11 9
1—t 6
\ 7
\ I \ r 1 19 3 8 4 20 17
I 13 18 2
I I I l^l*™! 5 16 15 12 14 10
Dentist Number h'ig. 2. The number of approximal surfaces viewed radiographieally that were considered to require filling by 20 dentists. The dentists have been grouped according to their reported restorative treatment thteshold (i.e. "Before ADJ", "At ADJ " or "ttito dentine").
Trctitmctit tlircstiohts atid agreemetit in trcattnenl
267
LANDIS & Korit's (25) interpretation of
Kappa scores (K =0.00 0.21), 79"/,, (150) of the 190 dentist pairings showed "lair o r tnoderate agtectnenl" in their decision-making (Kappa =0.21 0.6). No dentist pairing getierated a Kappa score greater than 0.81, "ahnost perfect agreement". Fig. 4 shows the agreement betweeti the 190 possible pairitig ofthe 20 dentists as measured by the Kappa statistic. The fignre has been shaded to highlight pairings who lepotted that they used the same restorative treatment thresholds. The tnean Kappa score of all the pairings was 0.46 atul ranged frotn 0.10 to 0.73: the highest level of agreetnctil was achieved between two dentists who claitned to intervene al different stages in the carious process, the lowest was betweeti a pair who claitned to itilct vetie at the same stage as eaeh other. The tneati Kappa score for pairs of dentists who claimed to think that a filling ought to be provided before a lesion h a d petietrated the AD.I was 0.41. Among pairs of dentists who thought a filling would not be requited utitil the AD.I had been reached, a mean Kappa of 0.50 was achieved and atnong those w h o said they would tiot fill until a lesioti h a d petietraled dentine, there was a mean level of agteetnent of 0.42. Ovetall thete was a tneati Kappa score of 0.44 betweeti dentists who claimed to interxene at a similar stage in lesion developtnent (pairs in all thtee shaded sectiotis of Fig. 3) and 0.44 betweeti detitists who claimed to u.se differing thteshokls (paits in the unshaded seetion of Fig. 3).
0.58 0.23 0.54 0.52 0.57 0.45 0.60 0.45 0.37 0.52 0.65 0.52 0.56 0.39 0.64 0.64 0.60 0.51 0.42 0.40 0.51 0.44 0.60 0.45 0.58 0.58 0.27 0.25 0.54 0.50 0.58 0.61 0.66 0.59 0.38 0.48
I 0.27 0.24 0.16 0.48 0.46 0.47 0.22 0.52 0.12 0.31 0.30 0.64 0.15 0,48 0.17 0.40 0.25 0.58 0.22 0.64 0.18 0.61 0.45 0.33 0.23 0.50 0.25 0.45 0.20 0.42 0.49 0.42
I Before ADJ At ADJ
0.51 0.29 0.51 0.66 0.50 0.50 0.59 0.59 0.51 0.61 0.21 0.35 0.42 0.52 0.69 0.67 0.63 0.63 0.23 0.20 0.53 0.54 0.60 0.54 0.44 0.52 0.31 0.29
Into Dentine _
•liiiYiii- m i l
0.3if 0.25 0.451 0.52 0.54 0.33 0.63 0.58 0,59) 0.44 0.31 0.23 0.41
0.55 0.36 0.42 0.54 0.42 0.35 0.41 0.30
0.38 0.73 0.56 0.26 0.49 0.62 0.63 0.41
0.35 0.70 0.43 0.62 0.44 0.56 0.14 0.34 0.42 0.56 0.39 0.52 0.45 0.57 0.15 0.37
0 44 0 62 0.3B 0 62 0.42 018 0.16 0 46 0.37 0 49 0.40 0 5."; 0,46 0.24^40
O.$5 0,03] 037 0.26 0 51 0.66 0.40 0.60 0.C8 0^4 0.48 0.54 0.62 0.25 0.45 0.28 0.37 0.23 0.36 0.38 0,41;
/•Vi,'. 4. Agreement on treatment of approxlnul suilaces \iewcd iadiogT,ipliic,ill> between each possible pairing ofthe 20 dentists assessed by the Kappa statistic ( ). The three shaded sections contain the Kappa seores between pairs of dentists who claimed to use the same restorative treatment threshold.
to be provided before ati approxitnal lesion had penetrated dentine in a Id-ytold patient. This appears to be sitnilar to previotts findings amotig Nortlierti Furopean detitists. HsriitJt) ct at. (22) teported that 65% ol'a sample of Norwegian dentists felt a filling would be required for a lesion which appeared radiographieally to have penettated "to the detitinoetiamel iunction". Mtt.t;MAN (5) reported thai jusi over 50" n of a satnple of Duteh dentists would plan a filling at the satne stage in a 15-yr-old. For patients aged 12 in Scotland, NUTTALL & PtTTS (19)
teported that 70% of dentists felt a filling would be required for a radiolucency which had reached tip to btit tiot beyond the AD,1.
Discussion
.igrccmcnt between restorative IrcatTlicte is a wealth of literatttte teportitig the degree of variatioti j o r i t y (55%) of the 20 dentists w h o took that can occur between treatment plans p a r t in this stttdy felt that a fillitig ottght fortnulated by different dentists on the basis of radiographic (1-6) atid elinical e\atnitiations(7 12). This study confirms Kappa scores the presence ofthis variation but suggests that tlie source of the variation is not wholly systetnatic. 27% 0.21-0.40 tnjlucnce of rcsloralivc treatment thrcsludds on restorative trcattnctit 0.41-0.60 planned This study suggests that testorative tteatment thresholds reported to be used by dentists tnay have little or no telationship to what they actually plan 52% to do on the basis of a radiographic exFig. 3. Distribution I'f Kappa Scores for UH) atnitiation. The titttiiber of fillitigs denti.st pairs.
Re.sroralivc treatment thresholds A tna- tnctit planned
planned was not significantly different between groups of dentists who said they intervetied at different stages in the carious process. Seven ofthe 11 dentists who said they would fill before a lesion had penetrated dentine, who would be expected to plan tnore fillings than dentists who intet vene at a later stage, had restorative plans which were well within the range of that planned by those who said they would wait until dentine had been petietrated. Furthertnote, it would be expected that the dilTetences in opinion as to the tnost appropriate stage of lesion developtnent at which a filling ought to be placed should lead to systematie variations between dentists. However, the tnean Kappa score between dentists who claitned to ttse the satne restorative treattnetit thteshold was exactly the satne as the tnean between dentists who disagreed about the tnost approptiate stage to fill. There may be several reasons for this. The first might be the extctit to which dentists agree on what is represented on a tadiograpli. The restorative treatment threshold deseriptions used in this study were based on actual penetration of the lesion as opposed to apparent penetration of the radiolucency. MtuiMAN (5) has suggested that dentists who advocate cotnparatively early intervention in the developtnent of caries may perceptually competisate for this to some extent by being rather tnore strict in their interpretation of radiographic e\'idence, in other
268
K A Y I-T A L .
words they might need rather more radiographie evidence before they think that an early lesion is visible on a radiograph than a colleague who claims not to fill until a tnore advanced level of caries. A seeond faetor is that dentists may find it difficult to interpret their "internal" representation of what constitutes a lesion in need of tteatment, in terms of a simple written description. There may in faet be a eotnplex web of cues and signs assoeiated with a lesion judged to need a filling, which the dentist may be unaware of. These may not readily translate to the descriptions used to determine a practitioner's restorative treatment threshold. A third element may be the value that dentists put on partieular types of errot\ A dentist tnay report a sitnilar treattnent threshold, and may interpret the radiographie depth of a lesion in a similar way to his colleague, and yet tnay adopt a more "interventionist" attitude, due to his belief that restorations offer a rapid and certain method of returning a tooth to health. Thus the implicit valuations plaeed by dentists on the outcomes of their deeisions may override the treatment thresholds which the dentists hold. The high agreetnents between sotne dentist pairs with unlike treatment thresholds and low agreetnent between some dentists with sitnilar thesholds suggest that stated treattnent thresholds have little intluence on restorative treament plans. If a dentist intends to treat all lesions which have penetrated to the inner half of the enamel, and believes that radiographs underestimate lesion depth, he would be expeeted to fill many teeth. However, these "knowledge" faetors could be compensated for by a eircumspect attitude to treatment and a wish to be highly specific rather than sensitive in his decisions. The dentist would therefore fill a similar nutnber of teeth to a dentist who intended to restore only dentine lesions and believed that radiographs over-estitnated lesion depth, yet wished to be highly sensitive in his deeision making. However, patients are individuals, so it is therefore possible that the value judgements itnplicit in dentists' decision-making stem frotn the values held by a dentist's patients. Such an argument tnight explain why different individuals with similar disease levels are frequently offered different treatments. If the hypothesis is correct, it also explains
why dilTerent dentists tnake dissitnilar plans for an individual patient, as the value judgetnents implicit in the dentist's decisions will be affected by the interpersonal eotnmunication between the dentist and patient. The source of the values itnplieit in a dentist's decision-making process is therefote highly itnportant to standardization in praetice. If, as sugge.sted by this study, the inherent attitudes of dentists have a stronger influence on treattnent planning than their ability to correctly detect pathology, theti the sourees of these attitudes must be sought befote dentists can be trained to make decisions in a standardized tnatitier.
9. MI;RRI:I 1 MCW. EI.I)I:RTON R.I. An i,i
12.
13.
14.
15. 16
17.
References 1. St!WtiRtN I, Sioi.TZi; K. Variabiliteten ved radiologisk cariesdiagnostik blandt X45 danske tandlaeger. Tinidhtegehhidet 1979; .V.i- .143 .SI. 2. Mlt.lMAN
PA,
PuRDtil.t.-LliWlS
3.
18
DJ,
Wt-t't.t': LT VAN UI;R. Variation in radiographic caries diagnosis and tieatment deeisions among university teachers. Communitv Dettl Oral Epidemiot 1982; 10: 329 .14. MlLliMAN P A , PUKOtit.t.-LtiWlS D.I. Wl'lil,l{
LT VAN DKR. Effect of variation in caries diagnosis and degree of caries on treatment deeisions by dental teachers using bitewing radiographs. Community t)eiit Orot Epidetniol 1983; //.• .V56- 62. 4. 1VIII.I;MAN PA, PtjRDt-MX-Ltiwts D.I, DtiMM!;R P. WI;I:I.I; LT VAN t)i;R. Diagnosis and treatment decisions when using bitewing radiographs - a comparison between two dental schools. ./ Dent 1985; /.?.• 140 51. 5. MtiJiMAN PA. Rddiograpliic cctries diagnosis and restorative treatment decisioii-niakitig. Thesis, Groningen: LIniversity of Groningen, 1985; 109-61. 6. lisi'HLtD I. Radiographic diagnoses and treatment decisions on approximal caries. Cotiimuititv Dciit Oral t^.ptdctiiiol 1986; 14: 265 70. 7. RYI'OMAA I, JARVINI:N V, JARVINI:N .1. Vari-
ation in caries recording and restorative treatment plan among university teachers. Communitv Dent Oral Epidemiol: 1979; 7: 335 9. 8. r,t,t)t:RtoN R.I, NUTTAi.i. NM. Variation among dentists in planning treattnent. Br Dent J 1983; 154: 201 6.
•
1 I. KAY liJ, WAI IS A, PAn;RsoN RC, BLINJ;^
Acknowledgetitents- Thanks to all the General Dental Practitioners who generou.sly gave their time. The stttdy was conducted at the Department of Public Health at Glasgow University. Dr Nt(:t:t. NtrrtALt, acknowledges funding from the Scottish Office's Home and Health Department who do not necessarily share the views expressed in this paper. Thanks also to Mr B.IORN AAt
Elizabeth Jane Kay\ Nigel Michael Nuttali^ and Robin Knili-Jones^ 'Department of Dental Health and 'Dental Health Services Research Llnit, University of Dundee. Dundee and 'Department of Public Health, tjniversity of Glasgow, Glasgow. Scotland
Kay E.I, Nuttail NM, Knill-Jones R: Restotative treatment thresholds and agreement in treattnent tleeision-making. Commtinity Detit Oral Epidemiol 1992; 20: 265-8. Abstract - It has been recognised for many years that treattnent deeision-making among dentists often shows wide variatioti. This study sought to examitie the effect of dentists' stated treatment thresholds as a source of variation between them. Twctity dentists made .^60 treatment decisions about the approxitnal stirfaces of extracted teeth seen in simulated bitewing radiographs. They also stated their personal treatment thresholds, i.e. the depth of lesion which they ititended to restore. One luindred and ninety pairwise comparisons of treatment decisions showed that only lOi'Vu ofthe dentist pairs showed substantial agreement. Dentist pairs who reported that they held the same iiiterveiitive threshold aehieved exactly the same metiti level ol agieenient in treatinent decisioii-tnakiiig as detitist pairs who disagreed about the appropriate threshold lor restorative intervention. The study suggests that restorative thresholds which are reported to be used by dentists may be poorly correlated with the ntiniber of positive treatment ileeisions actually made.
Many investigations have reported that there are elinically important differenees between dentists' interpretations ol diagnostic tests and the treatment deeisions which they subseqtiently make. Variations (I 12) in tieatment planning appear to be due to the cliniciatis' views as to the ability of a lesion to survive a given time period, or to their expectation of progression to pain and/or extraction of the tooth in question {5). Iherelore the thre.shold at which restoration becomes the optimal tteattiieiit decision ought to be related to the clinicians' knowledge of the rate and frequency of progression or regression of lesions (13) or to their view as to the radiographie appearance which represents the presenee of eavitation (14) as it is at this stage that lesion can no longer "regress" (15). It is thus understandable that the treattnetit thtesholds set by itidividual practitioners are not consistent with each other. However, studies which examitie observer variatioti (1-12), particularly those in which the treatment threshold is unequivocally laid down (16-18), suggest that there are further souiees of variation. Two ptocesses niay lead to these variations between clitiicians (10). E'irst, some may hold diffeiing opinions about what coti-
stitutes the optimum point for intervention (19). Secondly elinicians may perceive differetit costs and benelUs to be contingent upon their deeision (.5, 20, 21). NtniALL (10) diffetentiated between these two potential sources of dentists' discrepancies in treatment planning, as judgemental and perceptual variation. These differ in tiatuie from each other, .ludgemeiital variation is likely to stem from a consistent process - two dentists who have differing views about the stage ill the carious process at which a filling is requited (restorative treattnent threshold) will differ in a systetnatie way. A detitist who advocates earlier intervention than a colleague should only disagree about the treatmetit of lesions which he believes have reaehed a stage at whieh a filling is required but whieh his eolleague thinks ate not sufficiently advaticcd to tieed treatment. They will agree on the need to fill lesions which have progressed up to or beyond both their restorative treatment thresholds. Perceptual variation on the other hand was viewed by NtrriAt.t, (10) as stetntning from differing pereeptions of what dental eondition is aetually present. There might be a systematie eletnent in differing perceptions, for example where
Key words: agreement; decision-making; kappa; treatment thresholds E. J, Kay. Dept, of Dental Health, University of Dundee, Dundee. Scotland Accepted for publication 21 November 1991
one dentist always "sees" a cavity as larger than a colleague. However, there is also likely to be a larger non-systematic or randotn element involved, stemming in part from the weighting attached to eorreet and incorreet decisions (21). Several studies have shown that dentists report using differing restorative treatment thresholds {5. 19, 22-24). However, the extent to which these thresholds influenee testorative dental treatment deeisions has not been explored in detail. This study attempted to do so by comparing the restorative tieatment plans made by dentists on the basis of radiographic exatnination. with their views on when is the most appropriate point to intetvene. Materials and methods
Twenty randomly selected general dental practitioners in the City of Glasgow were provided with a list of descriptions of lesions affecting an approximal surfaee in a 16-yr-old who was described as having moderate earies experience and likely to attend the dentist again within a year. Each dentist was asked to indieate the point at which a filling would be required (restorative treatment threshold). The
266
KAY ET AL.
Eig. I. All example of the hitewiiig radiographs u.sed in Uie study.
descriptions used were: 1) The lesion has penetrated up to half of the enamel. 2) The lesion has penetrated into the deeper half of the enamel but has not reached the amelo-dentimal junction. 3) The lesion has reached the amelo-dentimal junction but has not penetrated dentine. 4) The lesion extends into dentine. 5) The lesion extends well into dentine. No dentist used category 1. Three categories were used in the analysis, these being: treatment thresholds Before ADJ (threshold 2 above). At ADJ (threshold 3 above) and Into Dentine (thresholds 4 and 5 above). The dentists were then asked to make restorative treatment decisions on the basis of 30 bitewing radiographs presented in pairs which had been taken of extracted teeth mounted to simulate a real mouth (Fig. I). Every dentist examined the same sets of radiographs to obviate problems of variable density and contrast. Each dentist made treatment deeisions concerning 360 tooth surfaces (12 surfaces per radiograph x 30 radiographs). The dentists were asked to view
the radiographs in the manner which they used in their day to day practice of dentistry. Subsequently the teelh used in the simulated radiographs were serially sectioned and the maximum depth of any approximal lesions rccotded. The criteria used are shown in Table 1. Results
Of the 20 dentists in the study, three stated that they intended to restore all carious lesions which extended beyond hall the thickness ofthe enamel ("Bcjorc ADJ"), eight dentists indicated that any lesions which had reached the amelodentinal junction should be restored ("At ADJ") and nine felt that a lesion should only be treated restoratively when it had penetrated into dentine ("Into Dentine"). Microscopic examination of the teeth which had been tised to simulate the radiographs after sectioning showed that 43 (12%) had dentinal caries and 52
(14'y(i) had lesions restricted to enaniel Further details of the detitists' decisions in relation to lesion depths in this study have been reported elsewhere (21, 24). Fig. 2 shows the number of fillings planned, grouped accotding to the den... tists' reported restoiative treatment thresholds. Paradoxically, one ofthe dentists (nutnber 11) who claimed to intervene at an early stage in the development of caries (i.e. before the AD.I) iilanneci fewest ftllings. The meati number of surfaees which would have been restored Viy those who would fill a lesion prior to its penetiatinglo the ADJ was 21. The mean number of surlaces lestored by those who said they would not fill a lesion until it had penetrated to the AD.I, was 36 and those who said they would wait until a lesion had cntctcd dentine, planned to restore a mean of 25 surlaces. Usitig yi analysis there were no dilferences in the mean nutnber of surfaces filled by the three grottps (P> 0.5). Iti total there were 574 decisiotis to restote tooth surfaces and 6626 that a filling wa.s tiot required If all decisiotis made by a dentist for each individual toolh stirfacc are conipated to all deeisions tnade by other dentists for that surface there are a total of 68400 paited eotnparisons. Overall 62974 (92'!4i) were in agreemetit. The probability that a dentist would agree with a decisioti to fill made by atiother dentist was 0.50. The probability that a dentist would agree with atiother dentist's decision not to fill was 0.96. iMg. 3 detnonstrates that b"/n (11) Q(tlie pairs of dentists obtained only "slight agreetnetit" with each other usintj
70-, 60
Tabel 1. Microscopic critcriji used lo validate dentists" decisions Score
Description
0 1
Sound Lesion confined to outer half of enamel Lesion penetrating the inner hall ol the enamel but not penetrating dentine Lesion into dentine but less than halfway to pulp Lesion into dentine and more than hallway to pulp Restored surface without faults Restored surface with faults Restored surfaee with caries (with or without faults) Missing data
2
4 5 6 7 9
Before ADJ
N
^°^
of
40 ^
Fillings Planned
At ADJ
50
Into Dentine
47
34
34 34 35
22 20 7 100-
a 11 9
1—t 6
\ 7
\ I \ r 1 19 3 8 4 20 17
I 13 18 2
I I I l^l*™! 5 16 15 12 14 10
Dentist Number h'ig. 2. The number of approximal surfaces viewed radiographieally that were considered to require filling by 20 dentists. The dentists have been grouped according to their reported restorative treatment thteshold (i.e. "Before ADJ", "At ADJ " or "ttito dentine").
Trctitmctit tlircstiohts atid agreemetit in trcattnenl
267
LANDIS & Korit's (25) interpretation of
Kappa scores (K =0.00 0.21), 79"/,, (150) of the 190 dentist pairings showed "lair o r tnoderate agtectnenl" in their decision-making (Kappa =0.21 0.6). No dentist pairing getierated a Kappa score greater than 0.81, "ahnost perfect agreement". Fig. 4 shows the agreement betweeti the 190 possible pairitig ofthe 20 dentists as measured by the Kappa statistic. The fignre has been shaded to highlight pairings who lepotted that they used the same restorative treatment thresholds. The tnean Kappa score of all the pairings was 0.46 atul ranged frotn 0.10 to 0.73: the highest level of agreetnctil was achieved between two dentists who claitned to intervene al different stages in the carious process, the lowest was betweeti a pair who claitned to itilct vetie at the same stage as eaeh other. The tneati Kappa score for pairs of dentists who claimed to think that a filling ought to be provided before a lesion h a d petietrated the AD.I was 0.41. Among pairs of dentists who thought a filling would not be requited utitil the AD.I had been reached, a mean Kappa of 0.50 was achieved and atnong those w h o said they would tiot fill until a lesioti h a d petietraled dentine, there was a mean level of agteetnent of 0.42. Ovetall thete was a tneati Kappa score of 0.44 betweeti dentists who claimed to interxene at a similar stage in lesion developtnent (pairs in all thtee shaded sectiotis of Fig. 3) and 0.44 betweeti detitists who claimed to u.se differing thteshokls (paits in the unshaded seetion of Fig. 3).
0.58 0.23 0.54 0.52 0.57 0.45 0.60 0.45 0.37 0.52 0.65 0.52 0.56 0.39 0.64 0.64 0.60 0.51 0.42 0.40 0.51 0.44 0.60 0.45 0.58 0.58 0.27 0.25 0.54 0.50 0.58 0.61 0.66 0.59 0.38 0.48
I 0.27 0.24 0.16 0.48 0.46 0.47 0.22 0.52 0.12 0.31 0.30 0.64 0.15 0,48 0.17 0.40 0.25 0.58 0.22 0.64 0.18 0.61 0.45 0.33 0.23 0.50 0.25 0.45 0.20 0.42 0.49 0.42
I Before ADJ At ADJ
0.51 0.29 0.51 0.66 0.50 0.50 0.59 0.59 0.51 0.61 0.21 0.35 0.42 0.52 0.69 0.67 0.63 0.63 0.23 0.20 0.53 0.54 0.60 0.54 0.44 0.52 0.31 0.29
Into Dentine _
•liiiYiii- m i l
0.3if 0.25 0.451 0.52 0.54 0.33 0.63 0.58 0,59) 0.44 0.31 0.23 0.41
0.55 0.36 0.42 0.54 0.42 0.35 0.41 0.30
0.38 0.73 0.56 0.26 0.49 0.62 0.63 0.41
0.35 0.70 0.43 0.62 0.44 0.56 0.14 0.34 0.42 0.56 0.39 0.52 0.45 0.57 0.15 0.37
0 44 0 62 0.3B 0 62 0.42 018 0.16 0 46 0.37 0 49 0.40 0 5."; 0,46 0.24^40
O.$5 0,03] 037 0.26 0 51 0.66 0.40 0.60 0.C8 0^4 0.48 0.54 0.62 0.25 0.45 0.28 0.37 0.23 0.36 0.38 0,41;
/•Vi,'. 4. Agreement on treatment of approxlnul suilaces \iewcd iadiogT,ipliic,ill> between each possible pairing ofthe 20 dentists assessed by the Kappa statistic ( ). The three shaded sections contain the Kappa seores between pairs of dentists who claimed to use the same restorative treatment threshold.
to be provided before ati approxitnal lesion had penetrated dentine in a Id-ytold patient. This appears to be sitnilar to previotts findings amotig Nortlierti Furopean detitists. HsriitJt) ct at. (22) teported that 65% ol'a sample of Norwegian dentists felt a filling would be required for a lesion which appeared radiographieally to have penettated "to the detitinoetiamel iunction". Mtt.t;MAN (5) reported thai jusi over 50" n of a satnple of Duteh dentists would plan a filling at the satne stage in a 15-yr-old. For patients aged 12 in Scotland, NUTTALL & PtTTS (19)
teported that 70% of dentists felt a filling would be required for a radiolucency which had reached tip to btit tiot beyond the AD,1.
Discussion
.igrccmcnt between restorative IrcatTlicte is a wealth of literatttte teportitig the degree of variatioti j o r i t y (55%) of the 20 dentists w h o took that can occur between treatment plans p a r t in this stttdy felt that a fillitig ottght fortnulated by different dentists on the basis of radiographic (1-6) atid elinical e\atnitiations(7 12). This study confirms Kappa scores the presence ofthis variation but suggests that tlie source of the variation is not wholly systetnatic. 27% 0.21-0.40 tnjlucnce of rcsloralivc treatment thrcsludds on restorative trcattnctit 0.41-0.60 planned This study suggests that testorative tteatment thresholds reported to be used by dentists tnay have little or no telationship to what they actually plan 52% to do on the basis of a radiographic exFig. 3. Distribution I'f Kappa Scores for UH) atnitiation. The titttiiber of fillitigs denti.st pairs.
Re.sroralivc treatment thresholds A tna- tnctit planned
planned was not significantly different between groups of dentists who said they intervetied at different stages in the carious process. Seven ofthe 11 dentists who said they would fill before a lesion had penetrated dentine, who would be expected to plan tnore fillings than dentists who intet vene at a later stage, had restorative plans which were well within the range of that planned by those who said they would wait until dentine had been petietrated. Furthertnote, it would be expected that the dilTetences in opinion as to the tnost appropriate stage of lesion developtnent at which a filling ought to be placed should lead to systematie variations between dentists. However, the tnean Kappa score between dentists who claitned to ttse the satne restorative treattnetit thteshold was exactly the satne as the tnean between dentists who disagreed about the tnost approptiate stage to fill. There may be several reasons for this. The first might be the extctit to which dentists agree on what is represented on a tadiograpli. The restorative treatment threshold deseriptions used in this study were based on actual penetration of the lesion as opposed to apparent penetration of the radiolucency. MtuiMAN (5) has suggested that dentists who advocate cotnparatively early intervention in the developtnent of caries may perceptually competisate for this to some extent by being rather tnore strict in their interpretation of radiographic e\'idence, in other
268
K A Y I-T A L .
words they might need rather more radiographie evidence before they think that an early lesion is visible on a radiograph than a colleague who claims not to fill until a tnore advanced level of caries. A seeond faetor is that dentists may find it difficult to interpret their "internal" representation of what constitutes a lesion in need of tteatment, in terms of a simple written description. There may in faet be a eotnplex web of cues and signs assoeiated with a lesion judged to need a filling, which the dentist may be unaware of. These may not readily translate to the descriptions used to determine a practitioner's restorative treatment threshold. A third element may be the value that dentists put on partieular types of errot\ A dentist tnay report a sitnilar treattnent threshold, and may interpret the radiographie depth of a lesion in a similar way to his colleague, and yet tnay adopt a more "interventionist" attitude, due to his belief that restorations offer a rapid and certain method of returning a tooth to health. Thus the implicit valuations plaeed by dentists on the outcomes of their deeisions may override the treatment thresholds which the dentists hold. The high agreetnents between sotne dentist pairs with unlike treatment thresholds and low agreetnent between some dentists with sitnilar thesholds suggest that stated treattnent thresholds have little intluence on restorative treament plans. If a dentist intends to treat all lesions which have penetrated to the inner half of the enamel, and believes that radiographs underestimate lesion depth, he would be expeeted to fill many teeth. However, these "knowledge" faetors could be compensated for by a eircumspect attitude to treatment and a wish to be highly specific rather than sensitive in his decisions. The dentist would therefore fill a similar nutnber of teeth to a dentist who intended to restore only dentine lesions and believed that radiographs over-estitnated lesion depth, yet wished to be highly sensitive in his deeision making. However, patients are individuals, so it is therefore possible that the value judgements itnplicit in dentists' decision-making stem frotn the values held by a dentist's patients. Such an argument tnight explain why different individuals with similar disease levels are frequently offered different treatments. If the hypothesis is correct, it also explains
why dilTerent dentists tnake dissitnilar plans for an individual patient, as the value judgetnents implicit in the dentist's decisions will be affected by the interpersonal eotnmunication between the dentist and patient. The source of the values itnplieit in a dentist's decision-making process is therefote highly itnportant to standardization in praetice. If, as sugge.sted by this study, the inherent attitudes of dentists have a stronger influence on treattnent planning than their ability to correctly detect pathology, theti the sourees of these attitudes must be sought befote dentists can be trained to make decisions in a standardized tnatitier.
9. MI;RRI:I 1 MCW. EI.I)I:RTON R.I. An i,i
12.
13.
14.
15. 16
17.
References 1. St!WtiRtN I, Sioi.TZi; K. Variabiliteten ved radiologisk cariesdiagnostik blandt X45 danske tandlaeger. Tinidhtegehhidet 1979; .V.i- .143 .SI. 2. Mlt.lMAN
PA,
PuRDtil.t.-LliWlS
3.
18
DJ,
Wt-t't.t': LT VAN UI;R. Variation in radiographic caries diagnosis and tieatment deeisions among university teachers. Communitv Dettl Oral Epidemiot 1982; 10: 329 .14. MlLliMAN P A , PUKOtit.t.-LtiWlS D.I. Wl'lil,l{
LT VAN DKR. Effect of variation in caries diagnosis and degree of caries on treatment deeisions by dental teachers using bitewing radiographs. Community t)eiit Orot Epidetniol 1983; //.• .V56- 62. 4. 1VIII.I;MAN PA, PtjRDt-MX-Ltiwts D.I, DtiMM!;R P. WI;I:I.I; LT VAN t)i;R. Diagnosis and treatment decisions when using bitewing radiographs - a comparison between two dental schools. ./ Dent 1985; /.?.• 140 51. 5. MtiJiMAN PA. Rddiograpliic cctries diagnosis and restorative treatment decisioii-niakitig. Thesis, Groningen: LIniversity of Groningen, 1985; 109-61. 6. lisi'HLtD I. Radiographic diagnoses and treatment decisions on approximal caries. Cotiimuititv Dciit Oral t^.ptdctiiiol 1986; 14: 265 70. 7. RYI'OMAA I, JARVINI:N V, JARVINI:N .1. Vari-
ation in caries recording and restorative treatment plan among university teachers. Communitv Dent Oral Epidemiol: 1979; 7: 335 9. 8. r,t,t)t:RtoN R.I, NUTTAi.i. NM. Variation among dentists in planning treattnent. Br Dent J 1983; 154: 201 6.
•
1 I. KAY liJ, WAI IS A, PAn;RsoN RC, BLINJ;^
Acknowledgetitents- Thanks to all the General Dental Practitioners who generou.sly gave their time. The stttdy was conducted at the Department of Public Health at Glasgow University. Dr Nt(:t:t. NtrrtALt, acknowledges funding from the Scottish Office's Home and Health Department who do not necessarily share the views expressed in this paper. Thanks also to Mr B.IORN AAt
