cervical dimensions for in situ and loose teeth: a critique of the hillson et al. (2005) method

Technical Note: Cervical Dimensions for In Situ and LooseTeeth: A Critique of the Hillson et al. (2005) Method

Bryan Scott Aubry*

Department of Anthropology, The Ohio State University, Newark, OH 43055

KEY WORDS cervicometrics; morphometrics; dental anthropology

ABSTRACT In 2005, Hillson and colleagues devel-oped a method for obtaining cervicometrics on a collec-tion of loose teeth. However, I identified problems withthe method when trying to apply it to material fromarchaeological collections with a mixture of in situ andloose teeth. The correct placement of the caliper tips atthe suggested mesiodistal landmarks proved impossiblefor many in situ teeth. Their recommendation to rotate

teeth to access the suggested landmarks resulted inlarge errors because not all teeth could be rotated. Otherproblems were identified with the suggested buccolin-gual dimensions of molars, which produced measure-ments that are not homologous across tooth classbecause of differential reduction in the distal cusps. AmJ Phys Anthropol 154:159–164, 2014. VC 2014 Wiley Periodi-

cals, Inc.

This article proposes changes to the current cervico-metric method. To demonstrate why these changes arenecessary, I examine why the results of Stojanowski(2007) differed so significantly from Hillson et al. (2005),despite using the same method. The revised method out-lined in this article allows researchers to consistentlytake the same measurements regardless of whether theteeth are in situ. An intraobserver analysis was con-ducted to test the repeatability of the dimensions out-lined here, and correlation coefficients were estimatedfor crown-cervical dimensions. The results are similar tothe Hillson et al. results in terms of error and in termsof correlation coefficients for crown-cervical dimensions,but the revised method has the benefit of being able tobe applied consistently to all types of skeletal samples.

In 2005, Hillson et al. (2005) brought renewed interestto cervical dimensions of teeth (FitzGerald and Hillson,2005, 2008) by proposing a new method for the collectionof such measurements and by designing special calipersto obtain them. One advantage of cervical dimensions isthat the cervix is than the crown less affected by bothinterproximal and occlusal attrition (Falk and Corruc-cini, 1982; van Reenan, 1982; Corruccini, 1987; Kieser,1990; Hillson, 1996; FitzGerald and Hillson, 2005). Wearaffects the reliability of using crown dimensions as aproxy for the underlying genotype for tooth size, even inmoderately worn teeth (van Reenan, 1982; FitzGeraldand Hillson, 2005; Hillson et al., 2005). Ideally, all teeththat exhibit significant wear should be excluded, but, asStojanowski (2007) notes, it is often difficult to removeall problematic teeth. Currently, it remains unresolvedwhat degree of wear necessitates exclusion from thesample, and the specific threshold is often unspecified inpublished research.

Hillson and colleagues appeared to have solved thisproblem by focusing on the cervix. According to the Hill-son et al. (2005) method, the mesiodistal (MD) dimen-sions for anterior teeth and premolars are recorded atthe most occlusal point on the curve at the cervical mar-gin on the mesial and the distal surfaces of the teeth(see Hillson et al., 2005:414, Fig. 1). For molars, a pointwas chosen midway along the cementoenamel junction

(CEJ) on the mesial and distal surfaces of the teeth (seeHillson et al., 2005:415, Fig. 2). Because the preciselandmarks are often difficult to reach from the labialposition, Hillson and colleagues recommend rotatingloose teeth to obtain an accurate measurement. Therotation of teeth was always possible in their studybecause they analyzed a sample of loose teeth. The buc-colingual (BL) dimensions for anterior teeth and premo-lars are recorded at the most apical point of the curveon the lingual and buccal surfaces (see Hillson et al.2005:414, Fig. 1). The BL dimensions are recorded usingthe caliper tips that meet end to end (located where theinside jaws would be on vernier calipers). For molars,the dimension is defined as midway along the buccaland lingual sides of the teeth, where there is usually aslightly depressed area between the roots (see Hillsonet al., 2005:415, Fig. 2).

THE PROBLEM

Hillson et al. (2005) demonstrated that all the dimen-sions of the CEJ and crown are positively correlated,and concluded that both yield the same biological infor-mation. They found slightly higher correlation coeffi-cients for BL comparisons. However, Stojanowski (2007)

Additional Supporting Information may be found in the online ver-sion of this article

Grant sponsor: National Science Foundation DissertationImprovement Grant: Grant sponsor: Award Number 0550902; Grantsponsor: Alumni Grant for Graduate Research (OSU); Grant spon-sor: Tinker Field Research Grant (Center for Latin American Stud-ies, OSU).

*Correspondence to: Bryan Scott Aubry, The Ohio State Univer-sity, 1179 University Drive, Lefevre 150, Newark, OH 43505.E-mail: [email protected]

Received 19 February 2013; accepted 11 January 2014

DOI: 10.1002/ajpa.22475Published online 23 January 2014 in Wiley Online Library

(wileyonlinelibrary.com).

� 2014 WILEY PERIODICALS, INC.

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 154:159–164 (2014)

applied the method to an archaeological sample, andnoted a different pattern. None of Stojanowski’s MDcomparisons for mandibular teeth were significant, whilecorrelation coefficients for some anterior teeth were neg-ative (Stojanowski, 2007). Interestingly, Stojanowski alsofound low correlations between antimeres for the ante-rior teeth. The BL dimensions were all significantly cor-related, with higher correlations for anterior teeth,similar to the Hillson study.

Why would two studies using the same methodologyyield such different results? It is proposed here that thiscan be explained by problems with the current methoditself, and that these problems likely derive from the

fact that the method was developed on a sample of looseteeth, which is very different from a typical osteologicalsample. One problem is that placing the caliper tips atthe MD landmarks described by Hillson et al. (2005) isimpossible for many teeth when measured in the jawbecause of the shape of the tooth at the cervical marginin cross-section (Supplementary information, Figs. S1and S2). For example, the current landmarks on upperpremolars are located at what is often the minimummeasurement (e.g., Fig. 1). There is a tendency to mea-sure loose teeth from the lingual side, as Hillson and col-leagues suggest. However, depending on the nature ofthe sample, some teeth can only be measured from thelabial/buccal aspect, whereas others, when jaws are frag-mented or teeth are loose, can be measured from the lin-gual aspect or with the back side of the calipers wherethe tips meet end-to-end. The problem is that the meas-urements can differ greatly depending on which positionis used (Table 1). The individuals in Stojanowski’s studywere of varying degrees of completeness (personal com-munication), so some teeth could be rotated but otherscould not, and such variability is typical of osteologicalcollections. As Table 1 illustrates, this variation greatlyaffects the resultant measurement.

Even if teeth are not rotated, Hillson and colleaguesdo not specify the angle the calipers ought to be placedwith respect to the cervical margin, and the angle of thecalipers introduces error. Because the labial/buccal por-tion becomes broader toward the neck of the tooth, thereis a tendency to tilt the calipers from a more apical posi-tion to access the defined landmarks. However, thisadjusted angle is only possible with older individualsbecause of alveolar resorption, and is usually not possi-ble for juveniles where the cervix of the tooth is oftenflush with the adjacent alveolar margin.

As described by Hillson and colleagues, the BL dimen-sions of molars fall at the approximate location wherethe mesial and distal portions of the crown meet.Unfortunately, this is also a common location for enamelextensions. In such cases, they suggest moving the cali-per tips to one side of the enamel extension or the other,“whichever produces the maximum BL measurement”(Hillson et al., 2005:203). As such, there seems to be anassumption that the maximum values (whether mesialor distal to the enamel extension) are actually homolo-gous, and that this measurement is homologous to BLmeasurements of molars lacking enamel extensions.

The BL dimensions of Hillson et al. (2005) are alsoaffected by a reduction in the distal component (e.g.,

Fig. 1. Apical view of an upper mesial premolar with an out-line showing the approximate location of the caliper tips for MDthe measurement outlined in this article (buccal is up). Hillson’slandmarks mark the minimum MD dimension for this tooth.

TABLE 1. Comparison of the mean mesiodistal tooth dimensions of loose teeth using the Hillson et al. (2005) landmarks fromlingual and labial/buccal position

Tooth N

Average measure-ment from lingual

position

Averagemeasurement

from labialposition

Difference inaverage

measurements

Number of teeththat deviate inmeasurement

Maximumdifference

Upper I-1 16 6.01 6.17 10.16 6 0.70Upper I-2 17 5.07 5.29 10.22 12 0.91Upper C 14 5.31 5.67 10.36 9 0.82Upper P3 11 4.29 4.83 10.54 10 1.04Upper P4 10 4.44 4.72 10.28 7 0.68Lower I-1 17 3.20 3.32 10.12 12 0.39Lower I-2 17 3.84 3.99 10.15 6 0.59Lower C 15 4.96 5.36 10.40 10 0.9Lower P3 15 4.61 4.75 10.14 7 0.37Lower P4 13 5.00 5.10 10.11 1 0.35

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American Journal of Physical Anthropology

metacone-hypocone). When measuring molars with alarge distal component, correct placement of the caliperstips is relatively simple. However, reduction of the distalcusps creates ambiguity and makes correct placement ofthe needle points more difficult (see Supplementary Infor-mation, Fig. S3). For example, if the hypocone is absent inupper molars, the measurement is essentially the breadthof the metacone. Therefore, as the distal portion of thetooth reduces in size, so does the dimension regardless ofthe size of the mesial portion. Taken to an extreme, whenupper molars completely lack the hypocone and the

metacone, the measurement landmarks no longer exist,and the BL dimension would be zero. Consequently, thisdimension, as defined by Hillson and colleagues is nothomologous between individuals with differential reduc-tion of the distal portion of the tooth.

THE SOLUTION

What is needed is a method that can both accommo-date the reality of samples that include loose teeth aswell as teeth embedded in situ within jaws. The methodmust also measure the same dimension of individualteeth consistently and repeatedly. The method proposedhere includes three revisions to the method described byHillson and colleagues. All measurements should betaken on the enamel surface at the cervix.

First, all MD measurements should be taken from thelabial/buccal side for all teeth, regardless of whether or

Fig. 2. Upper canine with caliper needle points indicatingthe appropriate angle that measurements should be taken (inline with the cervical margin).

Fig. 4. Occlusal view of upper left distal molar demonstrat-ing the approximate location of the BL landmarks as defined byHillson et al. (2005).

TABLE 2. Pearson product-moment correlations for maxillaryand mandibular crown-cervical comparisons

Tooth

Mesiodistalcrown-cervicalcomparisons

Buccolingualcrown-cervicalcomparisons

UI1 0.695 (165) 0.811 (164)UI2 0.734 (159) 0.898 (158)UC 0.701 (181) 0.811 (180)UP3 0.767 (197) 0.593 (197)UP4 0.719 (192) 0.759 (192)UM1 0.567 (181) 0.794 (180)UM2 0.611 (168) 0.597 (168)UM3 0.892 (108) 0.579 (108)LI1 0.629 (169) 0.660 (169)LI2 0.596 (165) 0.835 (165)LC 0.753 (193) 0.852 (193)LP3 0.716 (199) 0.779 (199)LP4 0.755 (199) 0.717 (199)LM1 0.634 (155) 0.689 (154)LM2 0.742 (165) 0.753 (165)LM3 0.848 (102) 0.585 (105)

Fig. 3. Upper mesial premolar with caliper needle pointsindicating the appropriate angle that measurements should betaken (note that the caliper tips are in line with the cervicalmargin).

CERVICAL DIMENSIONS OF TEETH: A CRITIQUE 161


TABLE 3. Intraobserver error analysis mesiodistal and buccolingual dimensions for each tooth

Tooth NStandarddeviation

Meanabsolute

errorPearson product-moment

correlation t-test

UI1MD Initial 28 0.44 0.082 0.975 0.654Repeat 0.42

UI1BL Initial 29 0.32 0.059 0.970 20.310Repeat 0.31

UI2MD Initial 26 0.41 0.084 0.965 1.345Repeat 0.44

UI2BL Initial 26 0.4 0.077 0.980 0.359Repeat 0.39

UCMD Initial 26 0.36 0.070 0.951 1.362Repeat 0.35

UCBL Initial 26 0.5 0.098 0.984 1.004Repeat 0.49

UP3MD Initial 23 0.33 0.073 0.960 0.802Repeat 0.36

UP3BL Initial 23 0.49 0.099 0.984 0.968Repeat 0.47

UP4MD Initial 24 0.45 0.087 0.959 20.728Repeat 0.4

UP4BL Initial 22 0.48 0.102 0.976 20.580Repeat 0.48

UM1MD Initial 24 0.38 0.072 0.930 20.364Repeat 0.33

UM1BL Initial 22 0.45 0.103 0.987 20.580Repeat 0.51





LI1MD Initial 27 0.21 0.038 0.901 1.228Repeat 0.18

LI1BL Initial 25 0.3 0.053 0.973 0.749Repeat 0.29

LI2MD Initial 28 0.3 0.057 0.948 1.499Repeat 0.31

LI2BL Initial 27 0.27 0.053 0.969 0.751Repeat 0.28

LCMD Initial 27 0.37 0.071 0.977 20.865Repeat 0.36

LCBL Initial 27 0.5 0.100 0.989 1.702Repeat 0.54

LP3MD Initial 25 0.28 0.057 0.936 21.222Repeat 0.29

LP3BL Initial 25 0.33 0.067 0.962 0.938Repeat 0.33

LP4MD Initial 27 0.45 0.084 0.968 20.153Repeat 0.42

LP4BL Initial 27 0.4 0.074 0.969 20.679Repeat 0.37

LM1MD Initial 21 0.43 0.117 0.721 0.612Repeat 0.64

LM1BL Initial 17 0.45 0.101 0.973 0.960Repeat 0.39





None of the t-tests are significant (P > 0.05).

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not the teeth are in situ, and the measurement must betaken in line with the cervical margin (Figs. 2 and 3,Supplementary Information, Figs. S4 and S5). The tend-ency to measure loose teeth from the lingual side, or toangle the calipers from a more apical direction should beavoided. For anterior teeth, the new measurement loca-tion should be moved to the maximum MD dimensionsup to the apical curve. Consequently, for anterior teeth,the revised dimension will often be labial to the land-marks identified by Hillson and colleagues (Fig. 1). Thismeasurement is fairly straightforward, and correctplacement is possible for all anterior teeth.

Second, for posterior teeth, the new MD measurementlandmark is in line with the buccal cusps (single buccalcusp for premolars; Supplementary Information, Fig.S6). The revised measurement for premolars and molarsis now the dimension of the buccal portion of the tooth,across the paracone/metacone for upper molars and theprotoconid/hypoconid for lower molars.

Third, for upper and lower molars the BL measurementshould be taken at the maximum breadth of the mesialportion of the tooth in line with the protocone/paraconeand the protoconid/entoconid for upper and lower molars,respectively (Fig. 4). This measurement location allowsfor the same measurement on all molars, regardless ofwhether the distal cusps are reduced in size. This mea-surement location also avoids enamel extensions.

A sample of 259 individuals possessing dentitions withlittle to no wear [Smith’s (1984) wear grade 1 or less]was used to estimate correlation coefficients betweencrown and cervical dimensions. The maximum crowndimensions were recorded at locations just occlusal tothe cervical landmarks, not the traditional maximumdimensions of the crown (e.g., Mayhall, 2000). Pearsonproduct-moment correlation coefficients were calculatedby dividing the covariance of the two variables by theproduct of their standard deviations. The correlation isdefined only if both of the standard deviations are finiteand nonzero. Large positive correlations (max value 5 1)indicate a positive linear relationship, and large nega-tive correlations (min value 5 21) indicate a negativelinear relationship. Correlation coefficients of 0 indicatethat the two variables are completely independent. Asubsample of 34 dentitions were selected and measuredon two different occasions to test the repeatability of therevised cervicometric method proposed here.

Excluding third molars, an average of 184 and 177crown/cervical comparisons were available for maxillaryand mandibular teeth, respectively (Table 2). Estimatesof correlation coefficients for crown/cervical BL dimen-sions (rBL 5 0.73) were close to those obtained for MDdimensions (rMD 5 0.71). The pattern of correlation coef-ficients is similar to the pattern seen in the Hillsonet al. (2005) study, with all crown/cervical dimensionsbeing significantly correlated at P < 0.001. The resultsobtained in the current study differ markedly from thoseobtained in Stojanowski’s (2007) study, and, unlike Stoja-nowski’s study, MD measurements of the cervix for ante-rior teeth were strongly correlated with the homologouscrown measurements (avg.MD 5 0.69).

The results from the intraobserver error analysis(Table 3) indicate very close agreement between mea-surement bouts, similar to Hillson et al. (2005) with lowmean absolute error estimates. As with that study, noneof the results were significant at P < 0.05. A Bland–Alt-man test indicates only a slight bias between the initialand repeated measurements (20.021).

IMPLICATIONS

This study proposes a cervicometric method, whichcan be used on any skeletal sample. The purpose of thisstudy was twofold. First, this study tests an alternatecervicometric method to determine repeatability of meas-urements regardless of the nature of the sample. Second,this study demonstrates the degree to which crown andcervical dimensions are correlated, while explaining whydifferent studies, using the same methodology, would getdiffering results. The changes to the current methodinclude:

1. Measuring the MD dimension of all teeth from thelabial side with the calipers following the line of thecervical margin.

2. Including only the buccal portion of the tooth in theMD dimension of posterior teeth.

3. Including only the mesial portion of molars in BLdimension.

The method outlined here is similar to Hillson et al.(2005) in terms of error and in terms of how well thecrown and cervical dimensions correlate. It is not sur-prising that the results of the Stojanowski and the Hill-son et al. studies differ. Hillson’s study produced highcorrelation coefficients since they had an “ideal” sample,where all teeth could be rotated. As described in thisarticle, the discrepancy between measurements takenfrom the lingual and labial position is greatest for ante-rior teeth, and this is also where we see low and evennegative correlations in the Stojanowski study. Stoja-nowski’s BL measurements had higher correlations,likely because the same dimension can be measured onboth in situ and loose teeth. These problems areaddressed with the method proposed in this article. Therevised method is repeatable and the dimensions arehighly correlated with the crown dimensions, and itallows for consistent measurements of teeth regardlessof the nature of the sample.

ACKNOWLEDGMENTS

I thank the many researchers and institutions in theU.S., Mexico, and Guatemala that offered me access to thevarious collections included here, including the PeabodyMuseum (Harvard University), the Instituto Nacional deAntropolog�ıa e Historia (INAH-Mexico City, Yucat�an,Campeche), the Universidad Aut�onoma de Yucat�an(UADY-M�erida); the Universidad Aut�onoma de Campeche(UAC-Campeche); Museo Nacional de Antropolog�ıa (Mex-ico City); Museo Nacional de Antropolog�ıa e Etnolog�ıa(Guatemala City); Salon 3 (Guatemala City); ParqueNacional de Tikal (Guatemala); and Parque Nacional deTeotihuac�an. I thank Bob Genheimer at the CincinnatiMuseum of Natural History for access to Fort Ancientskeletal material for the intraobserver error analysis.Christopher Ruff, Brian Hemphill, and two anonymousreviewers provided helpful comments, improving theclarity of the paper.

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cervical dimensions for in situ and loose teeth: a critique of the hillson et al. (2005) method

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