General cientai practitioners' evaluation ot the need tor extraction of asymptomatic mandibular third molars

Kerstin Knutsson', Berndt Brehmer^, Lett Lysell^ and Madeleine Rohlin^ 'Department of Oral Radiotogy. Centre for Orat Health Sciences. tVlalmo. Lund tJniversity; 'Department of Psychology. Universily of Uppsala; -^Department of Oral Surgery, Central Hospital. Kristianstad. Sweden

Knutssoti K. Utehtiict- B. Eysell E, Rohlin M; Getietal dctital ptactitioticrs' evaluat i o n of lhe need for exlraclion of asymptotiialic niatidibulat- ihird tiiolats. C'omniunily D c n t Ot-al Epidctniol 1992; 20; .347-50. Ab.sttact Thirty gctieral detital ptactilioners were asked lo evalualc Ihe need for e.xtracti(-iti of asyinptotiiatic tiiatidibular third molars. Tliirly-six niatidibulat- ihitd m o l a t s with equal disltibulioti of atigulat- posilions. itnpaclion slalus. tnales atul females and age groups vveic .seleeled. l o eslimale lhe eonsislency of llie evaluation. t h e 36 cases wet-e duplicated so that, in all. 72 teetii wet-e evaluated. The tiutnber o f molars propo.sed to be extraeted by the ob.servers varied IVom 0 to 26. There was n o thitd tnolar which all obscrvet-s agt-eed should be extracted. The two molat-s w h i c h mosl observers. 25 atui 2,3 of altogelher 30 ob.servers. propt-ised lo be exit-acted w e r e parlially covct-cd by soft tissue. The decision tiot to extract two niolat-s was unaiiinioits. Both ofthese wet-e eonipletely coveted by botie tissue atul positiotied vet-tically. The tnean (-iverall intt-a-observer agreement for the therapeutical decision wa.s 92";,, with a tatige of 69 lOO'Xi. The length of professional expet-ienee of the oh.scrver did not inllueticc the evaltiation whether or not to extraet. We conclude thiit there is a gt-eat variatioti an-iotig gctieral detilal pi-actilionei-s t-cgatding their evalualion on the need for t-emoval of asytnpiomalic tiiatidibular third molars.

T h e tnost cotntnon ititetvctitioti in oral s u r g e r y is the removal of impacted teeth ( 1 . 2). These operatiotis, lhe niajorily of w h i c h involve third molars, aeeount for a b o i i l 1/3-2/.3 of all sttt-gieal itilet-vent i o n s , thai is, about 25 000 antutally iti S w e d e n atui 2.25 tnillion in the US (2). T h e figures quoted for Swedeti and the U S do not iticlude the teeth that wete r e m o v e d by getieral practitionets. Iti the U S the estinialcd cosl of t-etnoval (-if impticted leeth between 150 atul 400 n-iillion dollars per yeat- (3). A s detiiographic atul disease pallcrtis c h i i n g c over litne. we cati expect ati itic r e a s c iti thitd molar itnpactioti and as a conscquenee a rise in third molar sutgical r e m o v a l s (4. 5). This calls for a deeper s t u d y itito llic validity of curtetil indic a t i o n s lot- ihis kind (-if siitgcty. especially s i n c e the pt-opliylactic ituhcali(-iti fot- t-cm o v ; i l of the tlittd tnolar was tnost It-cq u e n t (6). Befote actually opetatitig oti an asyn-iptotiiatic tliit-d niolat-, tlict-c arc u s u a l l y tht-ee levels of deeision-making.

Eirst. the general detiial pt-aclilionct- has to diagtiosc lhe itnpaction atui decide if it is t-elevatit to t-cfer the patient to a specialist iti oral surgery. The second level in the decision-tnaking process is Ihc (-ital surgeon's opinion (-in the t-elevatice of the prophylactic indicatioti and his cvalualioti of the paticnl concerned. The final, and not least itiiportatit. factor is the palietit's owti cslimalioti (-if the innitcncc of this proccdiit-c oti his (-ir her oral and getietal health. The aitn (-if this sUid\- was to desctibc how gctiet-al practitionct-s evaluate the ticcd fot-exltaclion atid how the posilioti atui impaclion status of asynipu-iinalic tiiatidibular thitd tiiolars itiniictice the evaluatioti. Material and methods Cases Asymptomatie mandibular third nu-ilars were selected so as to rept-csetii an equal distribution of males atid fetnales, age gt-oups, atigiilar positiotis atid impaclion status. Elms, half of the sub-

Key words: impacted tootti; oral surgery; third molar Kerstin Knutsson. Dept. of Oral Radiology, Centre for Oral Health Sciences. Carl Gustafs vag 34, S-214 21 Malmo. Sweden Accepted for publication 21 December 1991

jects wctc fctiialc palienls. Three age groups wete seleeted; 19 25 yt-. 26 40 yr atui 41 60 yt-. The atigular posilion w-as classified as vertical, tiiesioatigulat-. disloangitlar or liorizi-uital according lo ihc ctiteria pt-csented b\ Wixti u (7). The iinpaclion slalus was dixided into ihtee caleg(-)rics; 1) parlially coxered by sofl tissue. 2) completely coxered by soft tissue atid 3) coniplclel\- co\-et-ed by b(-itie tissue. Thus, iti otder to obtain (-)ne tnolar to tcprcscnt each age-group, each angulat- positioti and each itnpaction stalus, 36 third tiiolat-s were selcclcd. In ot-der 10 assess lhe eonsisteney of the evaluation, the 36 cases wete duplicated. Howevet-, when ptesetited to the observer the duplieate case was turned to the opposite side eompared lo Ihe original ease. Case presentation Eaeh c-if the 72 was pt-esenled as a t-adiograph (see Eigs. 1 and 2) wilh short text informing llic obser\er about the sex and age of Ihe palieni atul the itnpaetion status of the tnolar atul thai thete wet-e tio symptoms. The observers wet-e asked to evaluate


KNUtssoN tn At..

/-';'.?. /. Asytnplomatic mandibular third molars which all 30 oh.servers agreed should not he extracted. Both were completely covered by bone tissue and positioned vertically, a) Age of patient 35 yr. b) Age ol patient 60 yr.

whether (-ir not to cxtt-act the illuslraled third niolat-. Oh.wrvcrs The 72 cases were sent Ut 30 general dental pt-actitioners (GDP). half of whom were working in the Public Dental Health Service and half wete private praetitioners. The GPDs of the Public Dental Health Service were seleeled by a cotnmitlee of tht-ee persons (two consultants in oral surgery and periodontol(-)gy, respectively, atid the chait-i-nan of the County Dental Assoeiation) as tepresenting CJDPs of high professional standard. Those representing private praetiec wci-e also cotisidet-ed by c(-)nsultants of the National Health Insitraticc Board to teptesetit CiPDs of high standatd. I'liere were 9 female and 21 male dentists. The length of professional experience varied between I and 30 yr, with a tneati of 12 yr (Table 1).

nutnber of tn(-ilars which were suggested by Ihe ob.servers to be exlracled varied

from 0 to 26 out of the Mt leeth (Table I ). When the observer ptoposcd the minitnutn and maximum tuimber of (hird m o lars io be exlracled the tnean tiutnber was 12 and 13 tiiolars. t-espectivcly. The observers' decision to extract in t-clalion to the impaction status atul Ihc posilion o l ' l h e Ihit-d molar as well as the age of the patient is ptesetited iti fable 2. T h e t e was tio tliirtl molar which all 30 observers agreed should be exiraeletl. They were, however, u n a n i m o u s (-)ti the decision tiot lo extract two molars. Eig. 1 (a and b) prcsetils these Iwo molars, which wet-e cotnplelcly covet-ed by bone tissue and pt-isitioned vettically. As showti in fable 2. the tnipaclion status itillucnccd lhe decision lo exlracl a Ihird molat-. M o r e thati twice as many obset-vers proposed extt-action of in(-)lars that wete partially covet-ed by soft tissue e o m p a t e d to tnolats with other itnpacti(-)n status. Eig. 2 (a and b) presents lhe Iwo molars proposed for extraeti(-in by most ob.servers. T h e ob.set-vet-s wei-c ni(-)t-e iticlined to propose exlraclion of tiiolars

in a distoatigular posilion lliati in atiy other position. M(->re(-(ver, lhe (-ibscrvers pr(-)po.sed fewer exlraelions in patients over 40 yr thati iti patietits y(-)utiger tban 40 yt-. Intra-ohscrvcr performance Table 1 pt-esenls lhe intra-observcr agt-eemeiu on whether or nol lo cxltact for all 3 observets. 1 he tneati ovetall ttitra-obset-vcr agt-eetiietil was 92"n, wilh a range of 69 100'^ (25 to 36 molats of allogclhor 36 molars). The eottcspotuiing Kappa values wct-e 0.39 atul 1.0. Scveti observers ptesetited ati (-iverall agteetnetit of KM)",,. Ovetall, these seven observers sh(-)wed no prefetetiee for eilhet- tlierapeulic dcciI'ro/essiotial experiettce oJ the ob.setycr Thct-e was no cotinecli(-)ti between tbe observer's age, sex (-ir ptofessiotial experience and the decisioti to exlracl. Tbe mean tuimber of molars proposed lo be extracted was 12 by 15 observet-s witb I 1 yr professional experietiee ot- tiu-ire and II by 15 obsetvers with 10 yt- ot- less professiotial expeticncc.


These GPDs selected as (-ibsetvcts iti i|-iis slittly do nol neeessatily tept-esenl CiPDs in getietal. Oti llic olher hand, lhe aim of our sludy was tiol lo measutc Ihe general (-ipinion of GPDs on lhe third niolar probletn. Our melhod has mot-e in common wilh the first part ofa Delphi Exereise (8) where a "good respondent group" of ptofessionals with a good teputation ate asked to evaluate a |-irobletii. Tbe Results technique involves itulividual questionThet-e were wide individual differenees ing of the professiotials by questiotinaire in the evaluation whether to extt-act Ihc or interviews atui avoids iti Ihe firsl phase matidibular ihitd tnolats or not. T h e ditccl confrontati(-)n of the professionals with eaeh othet-. In (-)t-tler to sltiicUtte atul sitnplify ihc task, the tuttnbet- of clinical vat-iables was kepi low. The infortnati(-)n on lhe symptc-)ms was unequivocal itisofar as lhe obset-vers were lold that all cases were asymptomatie. All the patients weie at tbe age when the root formation of the molars is expected [o be completed (9). Besides, the tt-eatincnt choice was only dicholotnous. which tuosl tnedical acliotis are, tianiely to cxlt-acl or nol lo cxttacl ihc third molat-. Nevertheless, the variation Ei.i;. 2. Asymptomatic n-iandibular thit-d molars which wet-e parlially coveted by sofl tissue, a) atnong Ihe ob.servers was widec(-)ncertiitig Horizontal position. Age of patient 19 yr. 25 of 30 observers proposed thai this tnolar be lhe numbet- of tnolats proposed U-i be exextracted, b) Mesioangiilar position. Age of patient 31 yr. 23 of ,30 observers proposed that this Itaclcd. Iti tio case was the proposal lo exmolar be extraeted.

E.xtractioti of iitattdibtdar third molars T i i h l c 1. Number of asymptomatic mandibular third molars pi-(-iposed to be extracted in the 1st a n d 2nd observations and the ititra-observer agteetiient for lhe Judgtnents (/( = 36 thitd molars)

No. of third molars


.liidgment to extract No. 1 2 3

4 5 6


Professional experience (yr) 16

18 10 8 10 8 6 1

1st obs.

2nd obs.

t) 1 3 6 6 7 7


'l'(-i extract 0 t)

1 3

36 34 36

3 3 5 7

5 7 7

31 33 36 2S 33 33


9 9

8 9 8 9 9

4 5

It) 10 lt)

1 1






13 14

17 18

1 1 11



8 9 10

l o extract and not to extract

11 12 11 11 1 1


32 32 32 35














17 18








II 24

14 14

14 16 IS 13

14 13 14 12 13 9 14 14 20 20

36 32 32 32 33 25 30 28 35 35 36 36 35

20 21 ->2

23 24 25 26 27 28 29


30 10 5 8 11 6 24

15 10 16

14 I.s 15 19 17

21 21 21 21 -1-1


t r a c t a tnandibular ihitd tnolat- shated by a l l obset-vet-s. Eat-gc inlet-observer vatiat i o n s iti alliludes lo itealtnetil have ptev i o u s l y beeti t-ep(-)t-led for asytnpiomalic p e r i a p i c a l lesions also (10). O n e of lhe teasotis for lhe wide itilero b s e r v e r varialion in (-)ur study might be t h a t the clitiical cxpcricticc (-if llic ob-

14 10 17 15 2t) 20




22 21


servet-s differs and is highly inlluenccd by ptcvious cases whet-e palholog\- ultimalely developed. The dental professi(-in depetuls tiiaitily oti clitiical itnptessiotis atul general detilal ptaclitioners are nol Iraiticd iti epidemiology. "They have difficully distiiiguisliing between di.sease iticideticc and disease ptcxalcticc" (11) atui

T a b l e 2. Number of observers in agreement with themselves at the repeated observations ot thc d u p l i c a t c s l(-i extract asytiiptotiiatic mandibular third molars of diri'eient impaction status and p o s i t i o n tor patients of three different age groups ( = 3tl observers) Age group (yr) I n i p a c l i o u status


Par-li;ill> covered by soft tissue

Vertical Mcsioangular nistoangular llori/(-iiital

19 25

26 40

41 60

11 IS 17 15

13 23 13 22

13 9 10


Con-ipletelv covered by soft tissue

Vertical Mesioangiilar nistoangular 1 loi-i/(intal

3 8 5 9

8 2 10 7

7 6 16

Con-ipletely covered by bone li.s.siic

Vertical Mesioangular Distoangular llori/ontal

15 8 3 9

0 3 21

tl 6 1


ate itiHuenced by those teeth that cause problctns. Atiolher reasc-in f(-ir lhe wide variation atiu-itig Ihc observers tuighi be the uncertainty in predicting the clinical outcome of asymptomatic Ihird molars. The National Institute of Health held a consensus conference (-ui the tetnoval of third molars (12). Although the conleretiee agt-ced (-in well-defitied criteria for Ireatment once patholog> had developed, the conclusion was that ihcte was n(-i tcliable way to predict significant health pr(-iblcms due lo as\-mplomalic third molat-s. Iti llie 197()s theories atid practice of ptevetilive atid itUet-ccpli\e tiiedieine and denlistt-y designed lo avoid lulute pathol(-)gieal conditi(-ins wete established. Inllucticcd b\ lliesc it-cnds in pt-c\ciili\e detilislt-y. the oral surgeotis' tnain coiuribution to prevention of oral disease was lo t-einove asympt(-)inatic third molars. Such a general preventive indieation for tnolar tetnoval was f(-irtnulated by EASKiN (1,'^) and SiiiRA (14). They proposed ihat all thitd tiu-ilats which at lhe lime of tiot-mal eruption had not reached their functional posilioti should be prophylaetically removed. It is evident that this viewpoint on tt-eatment is n(->l shared b\ any of the (-ibservers in our study. Instead, the obset-vers seetii to be inlluenced by ccriaiti cues. e.g. the impacti(-in slatus. Molars partially C(-ivct-ed by soft tissue wete proposed lo be exiraeled by twiee as many (-ibservers compat-ed to nu-ilat-s totalK coveted b\' either S(-ift tissue or bone tissue. The tehtiivc weight of the diffct-etil eues will be further atialyzcd to eharaeterize the distt-ibuti(-in of the different (-ibserxers' strategies. Otie-fourtli of the observers presetited ;tti cxccptiotially high intraobsct-\-cr agt-cctnctit. As the obsct-vers were fully awat-c of the expcritnctital sititatioti. they tnay have suspeclcd ihat the satne cases wete examitied atul a few of them pt-(-ibably t-ecognised lhe duplicale eases. This cantiot be ruled (-iut since two observers conuiietucd on this tnattet-. This could imply that gtealer diffctctices tnighl occur under non-cxpcrimetilal condilions and wilh another dcstgti of the stud\. The (-ibsct-\crs should li;t\c c\aluatcd the origitial atul the duplicale cases on two diffetetil occasions wilh sotne titne iti belween. Howevet-. al the slarl (-if our study we considct-cd such a design very limcc(->nsutiiing. posing a risk of drop-out of observers.


KNU-rs.soN HT AL.

The results of this study are eomparable to those of studies on human judgment in a variety of areas (15). Aeeording to WicrroN (16), it seems likely that such studies on medical judgments have uncovered real differences in the way medieal personnel use information and tevealed that these differences result in variations in patient care and use of tnedieal resource. Eittle is known about how eues are seleeted and best presented to the observers. In medieine, three different types of cases have been used, e.g. simulated paper cases, paper cases from actual patients and actual live patients (16). Our cases are all frotn actual patients i-cferred for surgieal removal of their mandibular thitd tuolar to a specialist in oral surgery. We believe that the information yielded by the radiographs together with the written information about the elinieal eruption status is sufficient Ibr a GPD to reach a professional decision whether or not to reeommend extraetion. In a elinical setting, however, there at-e two further deeision levels before the operation is actually earried out; the deeisions of the oral surgeon and the patient. The oral surgeon's evaluation on the need for extraction of asymptomatic mandibular third molars is deseribed and

eotnpat-ed with the GDPs' evaluation in a sepat-ate paper (17).

References 1. LYSta.t, L. RotitJN M. Visdomstandcn i underkiikcn tetna for odontologisk konsensuskonferetLS? Tattdlaekitrtidniiigett 1984; 76: 402-5. 2. 'fiJt.t.ocH JEC, AN-rc-ZAK-Botj(-KOMS A. Decision analysis in the evaluation (-if clinical slrategies I'or the management of mandibular thitd tnolars. ./ Dettt Edttc 1987; 51: 652 60.

tiotts. Reading. MA: Addison-Wesley 1975; 3. 9. RANIANI:N AV. t'he age of eruption of i h e




3. Ttlt.t.O( It .lEC, ANt(-/.AK A A . Wtt,Kt;S .IW.

The application (->f decision analysis to evaluate the need for extraetion ol'asympU-imatic Ihird molars. ./ Oral Maxiilofac Surg 1987; 5: 855 63. 4. Goi.tMii'Kci MH, NtiMAt

General dental practitioners' evaluation of the need for extraction of asymptomatic mandibular third molars.

Thirty general dental practitioners were asked to evaluate the need for extraction of asymptomatic mandibular third molars. Thirty-six mandibular thir...
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