A metrical comparison of maxillary first premolar form

Distances from the central pit to the perimeter of the crown of permanent upper molars were measured on standardized occlusal photographs of dental casts representing 210 male and 181 female Aboriginals from Yuendumu in the Northern Territory of Australia. In both males and females the first molar was the largest tooth but it showed least variability. Variabilities of the distances tended to be greater for radii constructed in the buccolingual direction than for the transverse mesiodistal radii. The most marked size reduction in the molar series from first to third related to the distolingual part of the crown, which was also the most variable region. Size differences between molars in the mesial contour radii were not marked. Sexual dimorphism was evident in most crown radii, being most marked for the second molar.

mentioning

confidence: 96%

Contours of maxillary molars studied in Australian Aboriginals

Yamada

Brown

1988

“…Other investigators devised systems in which anatomical landmarks of the occlusal surface are defined and analyzed either as coordinate data or by multiple linear measurements expressing details of crown components (Biggerstaff, 1969;Corruccini, 1977aCorruccini, ,b, 1978Corruccini and McHenry, 1980;Lavelle, 1978Lavelle, , 1984Hartman, 1988Hartman, ,1989). …”

mentioning

confidence: 99%

Further analysis of mandibular molar crown and cusp areas in Pliocene and early Pleistocene hominids

Suwa

Wood

White

1994

Crown and cusp areas of mandibular molars were measured and analyzed on a sample of 249 specimens attributed to Australopithecus afarensis, A. africanus, A. (Paranthropus) robustus, A. (P.) boisei, and early Homo. In addition to intertaxon comparisons, we compared data that had been collected independently by two of the authors using methods that differ slightly in technique of measurement. Interobserver differences were evaluated by the t-test of paired comparisons, method error statistic, percent differences, and principal component analysis. Results suggest that between-technique error of measurement of overall crown area is small. Error estimates for individual cusp area measurements were of larger relative magnitude. However, these were not sufficient to detract from the conclusions derived from comparative analyses. Our results are in general agreement with previous assessments of early hominid dental size. Crown areas of A. africanus, however, exhibit a mosaic pattern, with M1 similar in size to that of A. afarensis and early Homo, and M2 and M3 similar in size to that of A. robustus. Intertaxon comparisons of relative cusp area were undertaken by univariate statistics and principal component analysis. These analyses revealed that while A. (P.) robustus and A. (P.) boisei both possess mandibular molars with cusp proportions significantly different from the 'non-robust' taxa, these differences are substantially greater in A. (P.) boisei.

“…1967; Moss and Chase, 1966;Hanihara, 1967;Lavelle, 1984). Unfortunately, the history of each tooth was not available but probably would not be very important to the primary goals of this particular study.…”

Section: Discussionmentioning

confidence: 93%

“…Biggerstaff, 1969; Lavelle, 1984;Moss and Chase, 1966; Moss et al, 1967;Perzigian, 1981; ; . Some of these studies were concentrated on a particular tooth within a tooth type.…”

mentioning

confidence: 99%

“…The mandibular first premolar was selected because it is known to be more variable in gross morphology than the maxillary premolar (Kraus, and Furr, 1953;Lavelle, 1984) and is one of the most variable teeth in the human dentition (Kraus, et al, 1969). Seventeen commonly occurring character traits, each having two or more variables, have been identified by Kraus and Furr (1953) in their observations of hundreds of lower first premolars.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Individual variation in enamel structure of human mandibular first premolars

Stern

Skobe

1985

Nine human mandibular first premolars were examined to assess variation in external morphology and enamel structural organization within a tooth type. The relationship of enamel ultrastructure to gross dental morphology was also studied. The teeth were cut in the mesiodistal direction just lingual to the buccal cusp, and etched. Montages were constructed of the cut enamel surface photographed in the scanning electron microscope at 100 X magnification. Parameters were measured and correlation coefficients were calculated for the comparison of various odontometric features. The mesiodistal and buccolingual dimensions were highly correlated and the occlusal thickness of enamel was significantly correlated to crown height but not crown width. Hunter-Schreger bands were less pronounced in fossa areas than at lateral aspects, cusps, or ridges; these bands were directly related to the geometry of the tooth. It was concluded that within this tooth type, there is a large amount of individual variation not only in gross morphology but also in enamel ultrastructure. This result underscores the fact that interspecific comparisons must be made with care.