The inclination between the posterior wall of the articular eminence and the referential
plane (Frankfurt line) was measured on 137 dry skull specimens (78 with complete
dental arches and 59 edentulous). Both left and right joints were measured using direct
craniometric method. The results were compared with respect to the loss of teeth, side
and sex. A large range of measured values of the eminence inclination shows great individual
differences, so that the mean values can have only orientational significance. The
mean value of eminence inclination for all measured specimens was 61.9 angular degree.
The difference between the two groups established upon dental status is very small
and without any statistical significance (P > 0.05). The right joint shows a slightly
steeper eminence inclination compared to the left one, but without any statistical significance
(P > 0.05). Asymmetry between the right and left joint appears almost as a rule,
while maximum measured differences reach up to 33°, with mean absolute difference of
6.9°. The group of edentulous specimens shows a greater symmetry and less differences
between the left and right joint, which indicates that different bimechanical conditions
in the joint, due to tooth loss might lead to remodellation of the articular eminence.The
eminence inclination was significantly steeper in male specimens in all subgroups (P <
0.001), which confirms sexual dimorphism

D. Buković Jr.

D. Vojvodić

D. Žabarović

K. Žabarović

V. Carek

V. Jerolimov

English

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Coll. Antropol. 24 Suppl. (2000) 1: 37–42UDC 572.544:616.314-089.23Original scientific paperThe Effect of Tooth Loss on theTM-joint Articular EminenceInclinationD. @abarovi}1, V. Jerolimov2, V. Carek1,2, D. Vojvodi}1,3, K. @abarovi}4and D. Bukovi}, Jr.21 Clinical Department of Prosthodontics, Clinical Hospital Dubrava, Zagreb, Croatia2 Department of Removable Prosthodontics, School of Dental Medicine, Zagreb, Croatia3 Department of Fixed Prosthodontics, School of Dental Medicine, Zagreb, Croatia4 Private practice, Zagreb, CroatiaA B S T R A C TThe inclination between the posterior wall of the articular eminence and the referen-tial plane (Frankfurt line) was measured on 137 dry skull specimens (78 with completedental arches and 59 edentulous). Both left and right joints were measured using directcraniometric method. The results were compared with respect to the loss of teeth, sideand sex. A large range of measured values of the eminence inclination shows great indi-vidual differences, so that the mean values can have only orientational significance. Themean value of eminence inclination for all measured specimens was 61.9 angular de-gree. The difference between the two groups established upon dental status is very smalland without any statistical significance (P > 0.05). The right joint shows a slightlysteeper eminence inclination compared to the left one, but without any statistical signifi-cance (P > 0.05). Asymmetry between the right and left joint appears almost as a rule,while maximum measured differences reach up to 33°, with mean absolute difference of6.9°. The group of edentulous specimens shows a greater symmetry and less differencesbetween the left and right joint, which indicates that different bimechanical conditionsin the joint, due to tooth loss might lead to remodellation of the articular eminence.Theeminence inclination was significantly steeper in male specimens in all subgroups (P <0.001), which confirms sexual dimorphism.IntroductionThe osseus parts of TM-joint, in addi-tion to other factors, exert important in-fluence upon the magnitude of the lowerjaw movement. Particularly, the slope of37Received for publication October 11, 1999.the posterior wall of the articular emi-nence and its inclination determine thecondile path which leads mandibulae inits movements. At birth, the articulareminence is completely flat,and its fullsize and shape are reached at the age oftwelve1. Its development depends uponthe intensity of mechanical forces pro-duced by the condile2. The investigationof skull specimens indicates that withyears the articular eminence inclinationbecomes steeper, and reaches its finalshape at the early adulthood3. Averageinclination values are ofen used in every-day practice, particularly in work witharticulators, despite the fact that the ar-ticular eminence inclination varies in-terindividually, that there is a differencebetween the left and right joint, and de-spite sexual dimorphism manifested bysteeper inclination in males4–6. On onehand some authors have found a connec-tion between the loss of teeth and the ar-ticular eminence inclination7,8, while onthe other such a relationship has notbeen statistically proven in other investi-gations3–6,9,10. A number of recent studieshave also approached the problem usingdifferent methods or different anatomicparameters11–15.The aim of the study is to investigatethe relationship between the articulareminence inclination and the loss of teethbased on direct measurements of the lar-gest available number of specimens fromthe existing osteologic collection.Material and MethodsA total of 137 dry skull specimensfrom the osteologic collection of the Insti-tute of Anatomy, School of Medicine, Uni-versity of Zagreb were included in thestudy. All selected specimens were with-out damage in the measured area (tube-rculum articulare, meatus acusticus ex-ternus and orbitae), and they all hadcomplete data on age and sex.All speci-mens were selected on the basis of dentalstatus and divided into two groups: 78specimens with complete dental arches,including some with a few teeth missing,but with preserved occusal contacts inmolar and premolar region (dentulous),and 59 specimens without teeth (eden-tulous).Table 1 shows that in the den-tulous group the average age of speci-mens was 33.4 years, and in the group ofthe edentulous the average age was 68.7years. There were more male specimens(93 or 67.9%), in relation to the femaleones (44 or 32.1%). As a conseqence of theintention to include in the study the larg-est possible number of specimens fromthe collection, there is a certain asymme-try in the number of specimens regardingtheir dental status and sex.The articularemience inclination (Figure 1) is the an-gle between the posterior wall of the ar-ticular eminence and the line which con-nects cephalometric points Porion-Orbi-tale (Frankfurt line). The measurementswere performed by direct craniomethricmethod, using triangle with goniometerand thin metal rod. The triangle was po-sitioned in such a way that the point 0°on the goniometer was leaned against themost prominent point of the articular em-inence and the longest side of the trianglewas set along the Frankfurt line. Thethin metal rod was set against the poste-rior wall of the articular eminence, andits projection on the goniometer was theexpected inclination expressed in angulardegrees (Figure 2). The results were sta-tistically analysed by SPSS program forWindows Release 6.1. at the level of de-scriptive statistics (mean – X, standarddeviations – SD and coefficient of varia-tions – CV), while the differences be-tween arithmetic means were tested forsignificance by the T-test. The percentageof equality and the mean absolute differ-ence were made in order to show asym-metry of the measured inclination of theright and left joint on the same skull.38D. @abarovi} et al.: The Effect of Tooth Loss, Coll. Antropol. 24 Suppl. (2000) 1: 37–42ResultsThe mean measured value for the emi-nence inclination in all measured speci-mens was 61.9° with the range of valuesfrom 30° to 94°. The right inclination wasslightly steeper than the left one, but thisdifference was not statistically signifi-cant (P > 0.05). The mean value obtainedin the edentulous group was slightly hi-gher than the one obtained in the den-tulous group (62.5°–61.5°), and withoutstatistical significance (P > 0.05). The em-inence inclination in males in all mea-sured specimens was significantly (P <0.001) steeper than in females, at the av-erage for 6.5°. This result was repeated inselected groups,only with different levelof significance (P < 0.05). Examining thesymmetry between the right and left jointof each particular skull (Table 3), showedthe equal values in only 5.1% of the totalstudied specimens. In the edentulousgroup this value was higher (8.9%) ascompared to the dentulous group (1.3%),while the range of differences was verywide(–28° to +33°). When comparing theabsolute mean differences (difference ob-tained by substraction of the value for theleft joint from the value for the rightjoint, regardless of sign »+« or »–«) theedentulous group shows a lower differ-ence (5.1°), while in the dentulous groupthat value is higher (7.7°). A higher per-centage of equality and lower value forthe mean absolute difference, proves thatmore symmetry and less difference of theleft and right joint is present in Eden-tulous skulls.39D. @abarovi} et al.: The Effect of Tooth Loss, Coll. Antropol. 24 Suppl. (2000) 1: 37–42Fig. 1. The inclination between the posteriorwall of articular eminence (a) and frankfurtline: porion-orbitale (b).Fig. 2. Method of measuring the degree of thearticular eminence inclination by trianglewith goniometer(a) and metal rod (b).TABLE 1SPECIMENTS IN GROUPS WITH AVERAGE AGE AND SEXNo. Males Females Average Age Age-rangeDentulous 78 54 24 33.4 18–56Edentulous 59 39 20 68.7 55–88Total 137 93 44 45.7 18–88DiscussionThe wide range of inclination valuesobtained interindividually in the studyindicates that the average values can beused just as an orientational informationand that it is not advisable to use them ineveryday practice. The same results werefound in several other investigations, inwhich similar or different methods wereused3–6, 10,16–19. The mean value of inclina-tion (61.9°) is much higher than the value(40°) found by Angel in 19483. Somewhatlower values (55°–61.7°) have been ob-tained by recent studies6,20,21. With al-most the same mean inclination values inboth selected groups in terms of the den-tal status, it might be concluded that theloss of teeth has no effect upon the articu-lar eminence inclination. Some previousinvestigations show the same relation-ship4–6,9,10, while the other claim just theopposite7,8. This study shows that theright joint has slightly steeper inclina-tion, considering the average values,while some other authors find the incli-nation of the left joint steeper6,16–18. Theprevious theory of the asymmetry of thearticular eminence inclination of the leftand right joint, has been confirmed by thepresent study. The symmetry is found inonly 5.1% of all specimens, while someother authors, in similar invastigations,found a higher percentage of equality(about 12%)6,18. The difference betweenthe left and the right joint is probablycaused by the predominant usage of oneside of the dental arches during chewing,and conseqently the distribution of thebiomechanical forces is not similar inboth joints. In the edentulous specimensmore symmetry and less difference in in-clination of both joints is found, as con-firmed elsewhere6,18. Thus, different bio-40D. @abarovi} et al.: The Effect of Tooth Loss, Coll. Antropol. 24 Suppl. (2000) 1: 37–42TABLE 2DESCRIPTIVE STATISTICAL PARAMETERS OF THE ARTICULAR EMINENCE INCLINATIONIN ANGULAR DEGREES (M = male, F = female, L = left, R = right)Dentulous EdentulousX Min-max SD CV X Min-max SD CVML 63.57 40–94 10.50 16.52% 65.48 35–94 10.51 16.05%R 63.35 31–88 12.60 19.98% 64.41 33–86 11.64 18.07%Total 63.46 31–94 11.55 18.20% 64.95 33–94 11.24 17.30%FL 54.83 38–80 12.72 23.19% 58.05 30–77 13.95 24.03%R 59.75 43–88 11.19 18.72% 57.95 34–77 13.44 23.31%Total 57.29 38–88 12.11 21.13% 57.85 30–77 13.52 23.37%TABLE 3INDIVIDUAL SKULL VALUES OF THE DIIFFERENCES BETWEEN RIGHT AND LEFT INCLINATION,DONE BY FORMULA: RIGHT INCLINATION MINUS LEFT INCLINATION (negative value meanssteeper left inclination, and positive value means steeper right inclination)InclinationsubstractedDentalstatusMeandifferenceMean absolutedifference% ofequalityRight-Left Dentulous 1.36 7.69 1.3%Edentulous –0.85 5.11 8.9%Total 0.4 6.88 5.1%mechanical conditions caused by ageingand influenced by the loss of teeth, mighthave some effect upon remodellation andreshaping of the articular eminence. Thesteeper inclination in males in relation tofemales, confirms the sexual dimorphismfound by other investigations4–6, which,however, was not statistically signifi-cant16,17.Conclusions1. The range of the values for the artic-ular eminence inclination is wide and itdiffers interindividually, regardless of theloss of teeth, side or sex.2. The average inclination values haveonly orientational significance.3. The loss of teeth shows no statisti-cally significant correlation with the emi-nence inclination.4. The right joint has steeper, but notstatistically significant eminence inclina-tion.5. The asymmetry between the leftand right joint is almost a rule, and thedifference reaches up to 30°.6. With the loss of teeth, the articulareminence inclination between the leftand right joint shows more symmetry andless differences.7. Sexual dimorphism is confirmed bystatistically significant steeper eminenceinclination in males, regardless of theside or loss of teeth.R E F E R E N C E S1. HUMPHREYS, H., Intern. J. Orthodont. Surg.Radiol., 18 (1932) 809. — 2. KAZANJIAH, V. H., Am.J. Ortodont., 24 (1988) 1181. — 3. ANGEL, J. L., Am.J. Anatom., 83 (1948) 223. — 4. JEROLIMOV, V., An-thropometric investigations of mandibular fossa ofthe temporomandibular joint in humans. In Croat. M.S. Thesis. (University of Zagreb, Zagreb, 1974). — 5.JEROLIMOV, V., V. BERGMAN, J. PERINI], Coll.Antropol., 18 (1994) 107. — 6. BERGMAN, V., Com-parative craniometric and cephalometric analyses ofthe posterior wall of the TMJ articular eminence in-clination in humans. In Croat. M. S. Thesis. (Univer-sity of Zagreb, Zagreb, 1991). — 7. CARLSSON, G. E.,Odont. Rev., 19 (1968) 171. — 8. FITZIG, S., M. GA-ZIT, Y. LIBERMAN, Abstracts of the EPA13thAnnualMeeting (1989). — 9. KLEINROK, M., Stomato.DDR., 29 (1979) 208. — 10. MONGINI, F., J. Pros-thet. Dent., 38 (1977) 439. — 11. VINTER, I., J. KRM-POTI]-NEMANI], D. IVANKOVI], D. JAL[OVEC,Coll. Antropol., 20 (1996) 555. — 12. CAREK, V., V.JEROLIMOV, D. BUKOVI], Jr., I. BAU^I], D. RA-DIONOV, Coll. Antropol., 21 (1997) 549. — 13. JE-ROLIMOV, V., P. KOBLER, J. KEROS, T. STANI^I],I. BAGI], Coll. Antropol., 22 (1998) 169. — 14. CA-REK,V., V. JEROLIMOV, A. ]ATOVI], D. BUKO-VI], Jr., Coll. Antrpol., 21 (1997) 211. — 15. BUKO-VI], D., Jr., D. RADIONOV, @. VERZAK, O. LULI]-DUKI], Z. AZINOVI], I. BAGI], Coll. Antropol., 21(1997) 217. — 16. CAREK, V., Relationship of TMJarticular eminence inclination with respect to thescull horizontal and medial planes. In Croat. M. S.Thesis. (University of Zagreb, Zagreb, 1974). — 17.CAREK, V., V. JEROLIMOV, A. ]ATOVI], Coll. An-tropol., 20 (1996) 63. — 18. KULIKOWSKA, J., Pros-thet. Stomatol., 26 (1976) 158. — 19. RICKETTS, R.M., J. Am. Dent. Assoc., 46 (1953) 620. — 20. REN, Y.F., A. ISBERG, P. L. WESTESSON, Oral. Surg. Oral.Med. Oral. Path. Oral. Radiol. Endod., 80 (1995) 258.— 21. SALVASTANO, C., R. CRACA, Minerva. Sto-matol., 40 (1991) 769. — 22. LEPERA, F., J. Prosthet.Dent., 24 (1970) 203. — 23. JEROLIMOV, V., V.BERGMAN, V. CAREK, EPA Conference, AbstractBook, (1992) 35. — 24. STIPETI], J., A. ^ELEBI],Coll. Antropol., 20 (1996) 97. — 25. CRADDOCK, F.W., J. Dent. Res., 32 (1953) 302. — 26. MACK, P. J., J.Dent., 3 (1984) 225. — 27. MATSUMOTO, M. A.,Braz. Dent. J., 5 (1994) 115.D. @abarovi}Clinical Department of Prosthodontics, Clinical Hospital Dubrava, Av. Gojka [u{ka 6,10000 Zagreb, Croatia41D. @abarovi} et al.: The Effect of Tooth Loss, Coll. Antropol. 24 Suppl. (2000) 1: 37–42UTJECAJ GUBITKA ZUBI NA NAGIB KONDILNE STAZE TM-ZGLOBAS A @ E T A KNa 137 preparata lubanja,78 sa sa~uvanim zubnim lukovima i 59 bez zubi, izmjerenje kut izme|u stra`nje stijenke zglobne kvr`ice i referentnog pravca – Frankfurtske ho-rizontale. Na istom preparatu mjeren je lijevi i desni zglob, a mjerenje je izvr{eno di-rektnim kraniometrijskim postupkom. Rezultati mjerenja su uspore|ivani u odnosuna zubni status, stranu i spol. Veliki raspon izmjerenih vrijednosti pokazuje da je nagibkondilne staze individualno vrlo razli~it, tako da srednje vrijednosti imaju samo ori-jentacijski zna~aj. Srednja vrijednost za nagib kondilne staze u ukupnom uzorku je61.9°. Uspore|uju}i odabrane skupine po vrsti ozubljenosti, razlika je vrlo mala i nijestatisti~ki zna~ajna (P > 0.05). Za desni zglob izmjeren je ne{to strmiji nagib kondilnestaze, ali ta razlika u odnosu na lijevi nije statisti~ki zna~ajna(P > 0.05). Asimetrijalijevog i desnog zgloba je gotovo pravilo i srednja razlika iznosi 6.9°, a najve}a izmje-rena razlika je ~ak 33°. U skupini preparata bez zubi uo~ena je ve}a simetrija i manjerazlike izme|u lijevog i desnog zgloba, {to upu}uje da druga~iji biomehani~ki uvijeti uzglobu, nastali gubitkom zubi, mogu utjecati na remodelaciju zglobne kvr`ice. Statis-ti~ki zna~ajno je strmija kondilna staza kod mu{kih preparata, kako u ukupnom uzor-ku, tako i po skupinama (P < 0.001), {to govori u prilog spolnog dimorfizma.42D. @abarovi} et al.: The Effect of Tooth Loss, Coll. Antropol. 24 Suppl. (2000) 1: 37–42

The Effect of Tooth Loss on the TM-joint Articular Eminence Inclination

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The Effect of Tooth Loss on the TM-joint Articular Eminence Inclination

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