Lease 2013.6 45 There have been very few studies focusing sole- ly upon the morphology of the deciduous denti- tion. Analyses of the deciduous dentition are usu- ally included as part of a larger study of the per- manent dentition, (e.g. Aguirre et al. 2006) or as an archaeological study (e.g. Sciulli 1998). A few ex- amples of population studies on the deciduous dentition include Jørgensen (1956), Hanihara (1968), Sciulli (1977, 1990, 1998), Harris (2001), Grine (1986) and Lease (2003). Rarely has African American dentitions been described independent- ly. The present study examines 25 morphological traits of the deciduous dentition in three samples: two African American samples from Memphis, TN and Dallas, TX (N= 218) and a European American sample (N=100) from Cleveland, OH. These traits represent the most commonly used traits in population microevolution studies, de- scribing various ancestral groups. The goal of the study is to provide a description of deciduous trait presence and trait variation within the African American samples. MATERIALS Morphological data were collected from a total of 318 individuals from three samples represent- ing two ancestral groups: African and European. The African American children are represented by 117 individuals from Memphis, Tennessee and 101 individuals from Dallas, Texas. The European American children are represented by 100 individ- uals from Cleveland, Ohio. Data were collected from two sources: dental stone casts and photographs. Dental casts were the primary resources for the Memphis, TN and the Cleveland, OH samples. The Dallas, TX sam- ple comprises of 5”x7”photographs taken in a pro- fessional laboratory (Condon et al. 1998). Casts were included in the study if they met the following criteria: morphological features were A descriptive study of African American deciduous dentition Loren R. Lease Department of Sociology, Anthropology, and Gerontology, Youngstown State University, Youngstown, Ohio 44555 Keywords: Dental Morphology, Biological Ancestry, ASUDAS ABSTRACT Descriptive studies of the deciduous dentition morphology have been presented as an inclusion in permanent dentition studies, the focus of archaeological populations or on specific traits within modern populations. The present study describes 25 morphological traits of deciduous dentition in two African Amer- ican samples from Memphis, TN and Dallas, TX (N= 218), and a European American sample (N=100) from Cleveland, OH. These traits repre- sent the most commonly used traits in population microevolution studies, describing various ances- tral groups. Results indicate trait frequency variation be- tween the two African American samples, as well as in comparison to European American samples. Traits varying in frequency between the two sam- ple populations include maxillary lateral incisor shovel shape trait (69% vs. 46%), canine tubercu- lum dentale (40% vs. 22%), canine mesial ridge (3% vs. 7%), and maxillary posterior molar hy- pocone development (76% vs. 92%). Trait frequen- cies higher than found in previous studies include maxillary central incisor shovel shape trait (38%) and maxillary lateral incisor shovel shape trait (68%), canine tuberculum dentale (40%), maxillary molar complexity (20%), cusp six (33%) and seven (68%), and the Y-groove on the mandibular poste- rior molar (69%). Trait frequencies seen lower in previous studies include tuberculum dentale trait on both maxillary incisors (8% and 3%) and the hypocone development of the maxillary posterior molar (76%). The level of trait expression is in- formative when comparing populations, especially the molar traits. For example, Carabelli’s pit/ fissure is the most common trait expression in Af- rican American samples, unlike European Ameri- can samples. Correspondence to: Loren R. Lease Department of Sociology, Anthropology, and Gerontolo- gy, Youngstown State University, Youngstown, Ohio, 44555 lrlease@ysu.edu 46 clearly visible, there were clear separations be- tween teeth, there was no stretching of the cast or chipping of the cast and at least one member of the antimere was present (Lease 2003). Photographs were included in the study if the morphology was clearly visible and no caries were present. Edgar (2002) tested the viability of using two different materials and found fewer morphological traits were visible for photographs; intra-observer error is no different than twice observing the same den- tition in the same format. The children (57 females and 60 males) who comprise the Memphis sample were routine den- tal patients seen during the 1990s at the Pediatric Dental Department of the University of Tennessee, Memphis (Lease and Harris 2001). The majority of the children resided in the “greater metropolitan area of Memphis” which includes suburban and urban areas around Memphis. The socio- economic status was described as middle class and they had access to health care at the University of Tennessee Medical Center (EF Harris, personal communication, 2003). Ancestry identification was determined by parents. The Dallas, TX sample consisted of 101 children buried in the Freedman’s Cemetery, the sex of whom was unknown. Individuals buried at the Freedman’s Cemetery were residents of urban Dallas. The cemetery was active from 1867 to 1907, with the majority of excavated burials dating from 1900 to 1907 (Condon et al. 1998). Juveniles in the study lived post-slavery (HJH Edgar, personal communication, 2003). All socio- economic status- es available to African Americans at the time are represented. The European American sample was collected at the School of Dentistry, Case Western Reserve University from the Bolton-Brush Longitudinal Growth Study. Ancestry came from parental de- termination. Data was collected on 50 males and 50 females born between 1920 and 1945 (Bailey 1992). The children resided in the urban areas of Cleveland, OH and were described as having ac- cess to good health care, education and nutrition (Bailey 1992). METHODS Morphological data consists of the scores of 25 deciduous traits. These 25 traits represent the most commonly used traits in micro-evolutionary studies and are the basis for creating Dental Mor- phological Complexes describing various ancestral groups (Jørgensen1956, Hanihara 1963, Hanihara 1966, Hanihara 1967, Grine 1986, Sciulli 1998). A complete description of expressions and traits can be found in Lease (2003). Morphological data were collected following Sciulli (1998). When present, both the right and left teeth of each individual were scored. If the expression of the antimeres was the same, that score was used as the expression of the tooth. If the score of a trait was different between the anti- meres, the more complex expression was used to represent the tooth. If only one tooth was present, that expression was used to represent the tooth. No root traits were collected due to the principle sources (casts and photographs). In the analysis and discussion of the morpho- logical traits, the use of the term “deciduous mo- lar” reflects the historic or traditional usage in dental anthropology and the scoring procedures (Lease 2003). Ontologically these teeth are premo- lars (Sciulli 1998). ANALYSIS Statistical analyses were performed in SAS ver- sion 8.02. The range of variation for each trait was calculated by expression frequencies for each sam- ple. The weighted average expression (W) was calculated for each feature: W = (Scixi/Sxi). Ci is the expression value and xi is the number of indi- viduals with that expression. The weighted aver- age is one method that captures where the range of variation within the sample lies. For example, the morphological trait of shovel shape for the maxillary central incisor has four expressions: 0, 1, 2, 3. The weighted average for this trait in the Cleveland sample is 1.15. ixi i)= ((0*28)+(1*40)+(2*21)+(3*11))/100 =1.15. Therefore, dichotomization into absence/ presence frequencies is between the expression class 1 and expression class 2 for the maxillary central incisor. The second analysis was performed to calculate the dichotomization of frequencies of the morpho- logical traits. Dichotomization (presence/absence) frequencies should reflect the weighted averages for each trait. 47 TABLE 1. Frequency counts and weighted averages The presence/absence frequency of a trait was calculated as in the following example using the shovel shape of the deciduous maxillary central incisor: Shovel shape : ui1 0 Absent: lingual surface smooth 1 Semi-shovel: slight 2 Shovel: marginal ridges present 3 Strong shovel: marginal ridges broad and wide Expressions 0 and 1 were designated as the ab- sence of the shovel shape trait and expressions 2 and 3 were designated as the presence of the trait in the individuals. The frequency of the trait (presence) in the population can then be expressed at p = 2-3 / 0-3, with 2-3 as the number of individ- uals having the expression 2 or 3 and 0 to 3 being the total number of individuals scored (Sciulli 1998). The presence frequencies for the anterior denti- tion traits among the three samples were tested for significance using Student’s T test (Tables 3-5). Expression frequencies for the posterior dentition were tested for significance (Tables 6-8). RESULTS Of the original 25 traits, nine traits had minimal variation within the samples (Table 1). These traits were: double shoveling, interruption grooves (for both the maxillary and mandibular central and lateral incisors) and posterior mandib- ular molar number. These traits were eliminated from further analyses.The remaining 16 traits were dichotomized for each sample either by absence/ presence (i.e. shovel shape) or by the feature ex- pressed (i.e. Carabelli’s cusp vs. pit) (Table 2). Five of the 12 anterior traits (Table 3) are signif- icantly different for the Cleveland and Memphis samples. The Memphis sample has greater per- centage for the maxillary lateral incisor and man- dibular canine shovel shape trait. The Cleveland sample has greater frequency for the maxillary incisors tuberculum dentale and maxillary canine distal ridge. The analyses of the posterior traits are found in Table 6. The majority of the traits examined for Cleveland and Memphis indicate that the Mem- phis sample exhibits higher frequencies for the more complex expressions. Regarding hypocone Trait Expression Cleveland Memphis Dallas N= 100 N= 117 N=101 i 1 ss 0 1 2 3 W 28 40 21 11 1.15 30 35 25 9 1.13 42 21 26 12 1.46 i 2 ss 0 1 2 3 W 10 39 28 22 1.63 31 35 39 11 1.26 31 23 31 15 1.30 ucss 0 1 2 3 W 14 38 34 14 1.48 35 30 36 16 1.28 38 26 25 13 1.13 i1ss 0 1 2 3 W 91 5 4 0 0.13 69 4 1 2 0.16 81 7 4 5 0.26 i2ss 0 1 2 3 W 67 26 6 1 0.58 80 17 4 2 0.30 69 11 11 10 0.62 lcss 0 1 2 3 W 34 44 19 3 0.91 48 36 17 12 0.94 45 18 22 16 1.09 i 1 ds 0 W 99 0.00 100 0.00 98 0.00 I 2 ds 0 W 98 0.00 114 0.00 97 0.00 ucds 0 1 2 W 94 2 3 0.08 114 1 0 0.01 98 1 1 0.03 i 1 interruption groove 0 2 W 100 0 0.00 100 1 0.01 98 0 0.00 48 TABLE 1., cont’d . development, Cleveland has higher frequencies for only having the eocone and protocone present (corresponding to Hanihara’s (1963) maxillary first molar morphology of 2), Memphis has higher frequencies of 4 and 5 (Hanihara’s (1963) 3H and 4 -/4) for the maxillary anterior molar. Similar re- sults are seen for the maxillary posterior molar. The Memphis sample has higher frequencies of the accessory cusps 6 and 7, as well as more cusps on the mandibular anterior molar. In addition, the individuals within the sample have higher fre- quencies of deflecting wrinkle and a pit/groove for the proto-stylid and the Y-5 molar pattern. For Carabelli’s trait, in the Cleveland sample the trait is more likely to be absent or a cusp, and in the Memphis sample,a pit. With regards to the mandibular posterior groove patterns, the Cleve- land sample more often exhibited the + pattern and Memphis the Y pattern. Comparing Cleveland and Dallas samples Frequencies of 11 of the 12 anterior traits (Table 4) are significantly different between the Cleve- land and Dallas samples. Dallas has higher per- centages for maxillary and mandibular central in- cisor shovel shape trait, mandibular lateral incisor and canine shovel shape trait and maxillary canine mesial ridge. Cleveland has higher presence rates for the maxillary lateral incisor shovel shape, the maxillary incisor and canine tuberculum dentale and the maxillary canine distal ridge. Similar results are found for the analyses of the posterior traits for the Cleveland and Dallas sam- ples (Table 7) with a few exceptions. Unlike the Cleveland/Memphis analysis of Carabelli’s trait, there is no statistical significance between the cusp frequencies for Cleveland and Dallas samples. Comparing Memphis and Dallas samples When comparing the two African American samples, four of the 12 traits are significantly dif- ferent (Table 5). The Memphis sample shows the shovel shape trait more often for the maxillary lateral incisor and canine, while the Dallas sam- ples has higher frequencies of that trait in the man- dibular central and lateral incisors. When comparing the posterior dentition traits (Table 8) for the two African American sam- ples,there are small differences in frequency ex- pressions. The Memphis sample has higher fre- quencies for the less complex expression for hy- pocone development for both maxillary molars, while Dallas is statistically significant for the more complex development expressions. Memphis Trait Expression Cleveland Memphis Dallas N= 100 N= 117 N=101 I 2 interruption groove 0 W 99 0.00 115 0.00 97 0.00 i 1 td 0 1 2 3 W 78 17 3 0 0.23 94 3 3 0 0.09 92 6 1 1 0.11 i 2 td 0 1 2 W 83 15 1 0.17 110 3 1 0.04 96 2 1 0.04 uctd 0 1 2 3 W 44 29 25 2 0.85 69 13 33 0 0.69 79 6 13 4 0.35 ucmr 0 1 2 3 W 98 1 0 1 0.01 114 2 1 0 0.03 96 4 2 1 0.11 ucdr 0 1 2 3 4 W 88 9 1 1 1 0.18 109 7 0 0 0 0.06 100 1 1 0 0 0.03 lcdr 0 1 2 3 4 W 99 0 1 0 0 0.02 112 1 3 1 0 0.09 101 0 1 0 0 0.02 49 Trait Expression Cleveland Memphis Dallas N= 100 N= 117 N=101 m 1 hypocone 2 3 (3M1 & 3M2) 4 (3H1 & 3H2) 5 (4- &4) W 61 22 12 5 2.61 16 22 57 20 3.70 3 19 60 20 3.95 m 2 hypocone 3 (3A) 4 (3B) 5 (4-) 6 (4) W 23 34 22 11 3.47 15 12 16 70 5.76 1 7 17 78 5.67 m 2 cusp 5 0 1 W 79 11 0.12 110 4 0.04 100 1 0.01 m 2 Carabelli’s trait 0 1 2 3 4 5 6 W 21 22 15 2 5 5 29 2.80 14 24 30 12 2 2 31 2.82 13 44 6 2 8 6 22 2.53 m1cusp number 3 4 5 6 7 W 0 38 51 9 1 4.73 3 40 59 8 3 4.72 5 27 54 15 1 4.80 m2 groove pattern 1 (+) 2 (x) 3 (y) W 64 2 31 1.66 42 5 60 2.17 23 7 68 2.46 m2 cusp number 1 2 3 W 1 95 3 2.02 0 87 26 2.23 1 68 26 2.26 m2 deflecting wrinkle 0 1 2 3 W 47 26 19 5 1.46 52 16 31 8 0.95 52 4 25 18 1.09 TABLE 1., cont’d 50 Trait Expression Cleveland Memphis Dallas N= 100 N= 117 N=101 m2 protostylid 0 1 2 3 6 W 90 0 5 4 1 0.28 90 20 2 2 0 0.26 59 35 3 3 0 0.50 m2 cusp 6 entoconulid 0 1 2 3 4 W 89 6 1 0 0 0.08 85 13 9 4 1 0.42 67 21 5 6 1 0.65 m2 cusp 7 metaconulid 0 1 2 3 4 5 W 39 15 30 15 1 0 1.24 36 7 45 19 4 1 1.56 51 4 20 17 7 1 1.28 m2 mesial trigonid crest 0 1 W 87 10 0.10 88 16 0.25 83 14 0.14 TABLE 1., cont’d shows a slightly higher frequency for the pit ex- pression while Dallas has a higher cusp expression for Carabelli’s trait. Memphis also expresses the + groove pattern more often than Dallas. Dallas has a higher frequency of the Y pattern. Memphis shows a higher frequency for cusp 6 in compari- son to Dallas. Dallas has a higher frequency for the mesial trigonid crest. CONCLUSIONS The analyses of the three samples indicate that African American deciduous dentition usually has the more complex expression of a posterior trait or has a higher frequency of an anterior trait. In com- parison to the European American sample, the African American samples have higher frequen- cies of: Shovel shape trait Mesial canine ridge Hypocone development on maxillary molars Carabelli’s pit or groove trait Y posterior mandibular molar groove pattern Deflecting wrinkle Pit/groove trait for protostylid Presence of cusps 6 and/or 7 However, the samples from Memphis and Dallas also have lower frequencies of tuberculum dentale and distal canine ridge traits, as well as the X and + posterior mandibular molar groove patterns in comparison to the Cleveland sample. ACKNOWLEDGEMENTS Dr. B. Holly Broadbent at The Bolton Brush Growth Study, Case Western Reserve University, Cleveland, OH; Dr. Edward R. Harris, The Univer- sity of Tennessee Health Sciences Center, Mem- phis, TN; Dr. Keith Condon, Freedman’s Cemetery of Dallas, TX; Dr. Qi Jiang, Youngstown State Uni- versity, Youngstown, OH. Research was support- ed by The Ohio State University Graduate Student Alumni Research Award. 51 TABLE 2. Dichotomization based on weighted averages Trait Absence Presence shovel shape 0, 1 2, 3 tuberculumdentale incisor 0 pits/grooves (1) canine ridge (2) maxillary canine mesial ridge 0 1+ maxillary canine distal ridge 0 1+ mandibularcanine distal ridge 0 1+ maxillary anterior molar hypocone 2 = 2, 3M1&3M2 = 3, 3H1&3H2 = 4, 4-and 4 = 5 maxillary posterior molar hypocone 3A = 3, 3B = 4, 4- = 5, 4 = 6 maxillary posterior molar cusp 5 0 1+ Carabelli’s trait absence (0), pit (1-3), cusp (4-6) cusp number of mandibular anterior molar 3 or 4 cusps = 1 5+ =2 groove pattern on the mandibular posterior molar + (1), X(2), Y (3) deflecting wrinkle 0, 1 2, 3 protostylid absence (0), pit/groove (1-2), cusp (3-4) cusp 6 0 1+ cusp 7 0-2 3-5 mesial trigonid crest 0 1 52 Cleveland Memphis % % p<0.05 i 1 ss 32 34.4 i 2 ss 51 68.7 0.000 ucss 48 45 i1ss 4 4 i2ss 7 6 lcss 22 38 0.000 i 1 td 17 3 0.000 i 2 td 15 2.6 0.000 uctd 25 28.7 ucmr 1 2.6 ucdr 11 6 0.025 lcdr 1 4.3 TABLE 3. Results: Cleveland and Memphis samples — anterior dentition Cleveland Dallas % % p<0.05 i 1 ss 32 38 0.014 i 2 ss 51 46 0.025 ucss 48 37.3 0.001 i1ss 4 9.3 0.025 i2ss 7 21 0.000 lcss 22 37.6 0.000 i 1 td 17 6 0.001 i 2 td 15 2 0.000 uctd 25 12.7 0.000 ucmr 1 6.8 0.014 ucdr 11 1.9 0.002 lcdr 1 0 TABLE 4. Results: Cleveland and Dallas samples — anterior dentition Cleveland Dallas % % p<0.05 i 1 ss 32 38 0.014 i 2 ss 51 46 0.025 ucss 48 37.3 0.001 i1ss 4 9.3 0.025 i2ss 7 21 0.000 lcss 22 37.6 0.000 i 1 td 17 6 0.001 i 2 td 15 2 0.000 uctd 25 12.7 0.000 ucmr 1 6.8 0.014 ucdr 11 1.9 0.002 lcdr 1 0 TABLE 5. Results: Memphis and Dallas samples — anterior dentition 53 Cleveland Memphis % % p<0.0.5 um1 hypocone 2 61 13.9 0.000 3 22 19 4 12 49.6 0.000 5 5 17.3 0.000 um2 hypocone 3 25.5 13 0.000 4 37.7 10.6 0.000 5 24.4 13.8 0.001 6 12 60.9 0.000 Cusp 5 12 3.5 0.004 Carabelli’s Trait absent 21 12 0.002 pit 39.4 57.9 0.000 cusp 39.4 30.7 0.004 cusp number of the mandibular anterior molar 1 38 38 2 61.6 68 0.014 groove pattern + 66 39 0.000 X 2 4.7 Y 32 56 0.000 deflecting wrinkle 24.7 38.2 0.000 protostylid Pit/ groove 5 19.2 0.000 cusp 5 1.7 cusp 6 1 24 0.000 cusp 7 16 21 0.025 mesial trigonid crest 10 5.4 0.025 TABLE 6. Results: Cleveland and Memphis samples — posterior dentition Cleveland Dallas % % p<0.0.5 um1 hypocone 2 61 2.9 0.000 3 22 18.6 4 12 58.8 0.000 5 5 19.6 0.000 um2 hypocone 3 25.5 0 0.000 4 37.7 6.8 0.000 5 24.4 16.5 0.008 6 12 75.7 0.000 cusp 5 12 1 0.001 Carabelli’s Trait absent 21 12.9 0.004 pit 39.4 51.5 0.000 cusp 39.4 35.6 cusp number of the mandibular anterior molar 1 38 31.4 0.008 2 61.6 69 0.008 groove pattern + 66 23.5 0.000 X 2 7 0.025 Y 32 69.4 0.000 deflecting wrinkle 24.7 43.4 0.000 protostylid Pit/ groove 5 38 0.000 cusp 5 3 cusp 6 1 33 0.000 cusp 7 16 25 0.002 mesial trigonid crest 10 14 TABLE 7. Results: Cleveland and Dallas sample — posterior dentition 54 Memphis Dallas % % p<0.0.5 um1 hypocone 2 13.9 2.9 0.001 3 19 18.6 4 49.6 58.8 0.002 5 17.3 19.6 um2 hypocone 3 13 0 0.000 4 10.6 6.8 5 13.8 16.5 6 60.9 75.7 0.000 cusp 5 3.5 1 Carabelli’s Trait absent 12 12.9 pit 57.9 51.5 0.014 cusp 30.7 35.6 0.025 cusp number of the mandibular anterior molar 1 38 31.4 0.008 2 68 69 groove pattern + 39 23.5 0.000 X 4.7 7 Y 56 69.4 0.000 deflecting wrinkle 38.2 43.4 0.025 protostylid Pit/ groove 19.2 38 0.000 cusp 1.7 3 cusp 6 24 33 0.002 cusp 7 21 25 mesial trigonid crest 5.4 14 0.002 TABLE 8. Results: Memphis and Dallas sample — posterior dentition 55 LITERATURE CITED Aguirre L, Castillo D, Solarte D, Moreno F. 2006. Frequency and Variability of Five Non- Metric Dental Crown Traits in the Primary and Permanent Dentitions of a Racially Mixed Popu lation from Cali, Colombia. Dent Anthropol 19: 39-48. Bailey J. 1992. The long view of health. 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