Dental Dimensions Research Articles

Mandibulofacial Adaptations in a Juvenile Animal Model of Temporomandibular Joint Arthritis

Juvenile rheumatoid arthritis (JRA) is a chronic systemic disease of childhood that affects synovial joints including the temporomandibular joint (TMJ). Individuals with JRA of the TMJ frequently show aberrations in mandibulofacial development. Since the basis for these developmental perturbations is poorly understood, they remain a perplexing clinical problem to manage. To begin dissecting the mechanisms for altered craniofacial development in JRA of the TMJ, we characterized the gross morphologic adaptations in the facial skeleton in a juvenile animal model of TMJ arthritis. Arthritis was induced in ten 87-day-old male rabbits by intra-articular challenge with ovalbumin. Eight sham-challenged and 4 unchallenged rabbits were used as controls. Serial lateral head cephalograms, taken at 73 (T1), 87 (T2), 108 (T3), 129 (T4), and 150 (T5) days of age, were evaluated by linear measures of maxillary, mandibular, and posterior dental height dimensions. Differences in the absolute dimensions and relative percent incremental changes were compared by ANOVA and Fisher's test. The body weights, as well as the absolute measures and incremental changes in maxillary and posterior dental height dimensions, were not significantly different between the antigen-challenged and control groups. In contrast, absolute measures of posterior mandibular height, condylar neck height, and total mandibular length were significantly smaller (P < 0.05) in antigen-challenged rabbits than in both control groups at T5. Furthermore, the antigen-challenged rabbits demonstrated significantly smaller (P < 0.05) relative increases in all measures of mandibular length, and in total posterior mandibular and condylar neck heights. Cephalometric superimpositions on the cranial base and tantalum implants confirmed these quantitative observations. This investigation demonstrates mandibulofacial developmental aberrations in experimental JRA-like disease of the TMJ that are similar to those observed in humans with this disease.

Constraints on masticatory system evolution in anthropoid primates.

It is well established that some observed patterns of force production in the primate masticatory system match those predicted by a simplified lever model. This model is also commonly invoked in adaptive explanations of craniodental diversity. However, systematic studies of the predictive power of this model are missing, leaving open the possibility that factors not traditionally included in the model alter the function and evolution of the masticatory system. One such factor was proposed for mammals generally by Greaves ([1978] J. Zool. (Lond.) 184:271-285), who argued that the temporomandibular joint (TMJ) was poorly suited to being pulled apart. In this constrained lever model, the avoidance of joint distraction leads to limitations on masticatory system form and function. The goal of the present study was to quantify masticatory system diversity in anthropoid primates for comparison with these predictions. Results indicate that all sampled taxa exhibit a form that is consistent with selection against regular distraction of the TMJ. Also apparent from observed patterns of scaling is a regular interaction among a limited set of cranial and dental dimensions, in accordance with the constrained model. However, the data indicate that specific positional relationships among the muscles, joints, and teeth differ from those predicted by Greaves (1978). The pattern of deviation suggests that selection has favored a conservative masticatory system configuration that safeguards the TMJ from distraction during the dynamic processing of irregular foods. The resulting buffered model leads to alternative hypotheses regarding the response of the masticatory system to dietary selection pressures. It may, therefore, improve our understanding of the adaptive significance of primate craniofacial form.

The association between dental arch dimensions and occurrence of Finnish dental consonant misarticulations in cleft lip/palate children

The aim of this study was to examine whether maxillary and mandibular dental arch width, length, and palatal height dimensions are associated with the occurrence of misarticulations (phonetic or phonologic errors) in the dental consonants /r/, /s/, and /l/ in different cleft types and sexes. The subjects were 263 (109 girls, 154 boys) 6-year-old Finnish-speaking non-syndromic children with isolated cleft palate (CP, n = 79), cleft lip/alveolus (CL(A), n = 77), unilateral (UCLP, n = 80), and bilateral (BCLP, n = 27) cleft lip and palate. Dental plaster casts were measured by two authors using the technique of Moorrees, and auditive speech was analyzed with high reliability by two speech pathologists. The results showed that the occurrence of misarticulations increased and dental arch dimensions decreased with the severity of the cleft. Narrower and shorter maxillary arches as well as shallower palates were related to problems with the studied dental consonants. Mandibular arch dimensions were not related to the misarticulations. However, statistical analysis did not reveal significant differences in dental arch dimensions between subjects with and without misarticulations when they were compared separately for different cleft types. The etiology of clefting per se-isolated cleft palate versus cleft lip with or without cleft palate-did not seem to explain the associations between dental arch dimensions and the studied misarticulations.

Dental size and shape in the Roman imperial age: two examples from the area of Rome.

Different socioeconomic strata of Roman imperial age are represented by two large dental samples recovered from archaeological excavations near Rome, Italy. Teeth are investigated for crown dimensions and morphological variants. One sample, comprising 1,465 permanent teeth, represents the rural town of Lucus Feroniae (LFR) and is mainly composed of slaves and war veterans. The other, comprising 734 teeth from the Isola Sacra necropolis at Portus Romae (NIS), represents the "middle class" segment of an urban population. Both series show small dental dimensions and fit at the lower end of the trend toward dental reduction in Europe from the Upper Paleolithic to the historical times. The urban sample is less variable metrically and less sexually dimorphic than the rural one. The analysis of discrete crown traits shows absence of rare phenotypic variants in both series. The urban sample is also less variable in this last respect, suggesting that the gene pool of this particular "stratum" of the NIS population was more homogeneous than that of LFR. The occurrence of enamel hypoplasia indicates that metabolic stress during growth and development was similar in LFR and NIS. The overall set of available data is evaluated in the light of the history of the two Roman sites and the composition of each population.

Comparative application of the coefficient of variation and range-based statistics for assessing the taxonomic composition of fossil samples

Abstract Dental variation has been used commonly to assess taxonomic composition in morphologically homogeneous fossil samples. While the coefficient of variation (CV) has been used traditionally, range-based measures of variation, such as the range as a percentage of the mean (R%) and the maximum/minimum index (Imax/min) have recently become popular alternatives. The current study compares the performance of these statistics when applied to single- and pooled-species dental samples of extant Cercopithecus species. A common methodology for such problems of species discrimination has been to simply compare the maximum value of a variation statistic observed in extant samples with that observed in the fossil sample. However, regardless of what statistic is used, this approach has an unknowable Type I error rate, and usually has low power to detect multiple species. A more appropriate method involves a formal hypothesis test. The null hypothesis is that the level of variation in the fossil sample does not exceed what might be expected in a sample drawn randomly from a reference population, taking into account sampling error and the size of the fossil sample. Previous research using this method with the CV has indicated that it offers considerable power at an acceptable Type I error rate. In the current study, the data of primary interest were posterior dental dimensions for single- and pooled species samples from extant Cercopithecus species. In addition, the study also investigated the relative performance of variation statistics when applied to highly dimorphic canine dimensions, since much recent work has employed sexually dimorphic dental dimensions for assessing single-species hypotheses. The results indicate that the CV consistently out-performed the range-based statistics when using posterior dental dimensions to test a single-species hypothesis. Regardless of which statistic was used, tests on sexually dimorphic dimensions offered minimal power. In consideration of these results and the problem of studywise Type I error rates, we recommend against the use of multiple measures of variation to test for multiple species composition, and advocate the CV as the statistic of choice when using the method of Cope & Lacy (1992). For similar reasons, we argue for careful selection of dental variables for inclusion in such analyses, and in particular recommend against including sexually dimorphic dimensions when testing for multiple species composition.

Rapid morphological change in Miocene marsupials and rodents associated with a volcanic catastrophe in Argentina

ABSTRACT Large fossil samples collected from a continuous series of stratigraphic levels are ideal for studying the tempo and mode of phyletic evolution. Study of two such coeval mammalian lineages (caenolestoid marsupials and octodontoid rodents) from Miocene rocks of southern Argentina revealed marked, simultaneous changes in molar dimensions in both lineages. The changes occur across a 1.65–1.80 m thick tuff unit that covers a widespread bonebed. Geologic and taphonomic data indicate that the tuff unit marks the rapid (geologically instantaneous) burial of an ancient land surface by pyroclastic products of a single major volcanic eruption. This suggests that the morphological changes observed in the fossil mammal samples were associated with catastrophic reduction in population size or the local or regional extermination of small mammal populations. Samples of both lineages showed changes in dental dimensions that are not simply the continuation of long-term morphological trends established before the ...

Human dento‐gnathic metric variation in mesolithic/neolithic Ukraine: Possible evidence of demic diffusion in the Dnieper Rapids region

Dental and gnathic metrics from a series of Mesolithic and Neolithic cemetery samples in the Dnieper River valley (Ukraine) are compared. Both male and female Neolithic samples have larger dental dimensions, wider dental arcades, and a more robust mandibular corpus than do the Mesolithic samples. In addition, the relative variances (RVs) of bucco-lingual dental breadths (as measured by modified Levene's Tests) show an intriguing pattern of change from the Mesolithic into and through the Neolithic. Female RVs show a clear tenency to increase through time, while male RVs show more mixed tendencies. Such a pattern indicates that the increases in Ukrainian Neolithic dento-gnathic dimensions are plausibly attributable to low intensity gene flow (demic diffusion). Seen in the light of new chronometric, paleodietary, and paleolinguistic information, as well as in the context of recent archaeological models for agro-pastoralist origins in the North Pontic, these data suggest that gene flow via population interactions originating in or transient through the circum-Caucasus may have played an important role in producing the Ukrainian Neolithic dental increase.

The Atapuerca dental remains. New evidence (1987-1991 excavations) and interpretations

Abstract The metrical features and some morphological traits of 133 permanent teeth from the site Sima de los Huesos (Sierra de Atapuerca, Burgos, Spain) are analysed and compared with those of other hominid samples. Since the sample sizes were greater for the lower than for the upper teeth, the main conclusions are fundamentally based on the analysis of the mandibular dentition. As an extreme case of the mosaic evolutionary pattern which characterizes hominid dental evolution, the Atapuerca lower dentition shows a strong imbalance between the size of the anterior (I1-P3) and posterior (P4-M3) teeth in relation to modern humans, and even with regard to other middle Pleistocene hominids and the Neandertals. On the average, the dimensions of the Atapuerca mandibular posterior teeth are similar to those of modern humans. Probably very much related to this, the hypoconulid was frequently absent in the lower molars. These observations imply that the selective pressures which operated to maintain a certain size of the posterior dentition during the middle Pleistocene were less restrictive than is assumed by previous evolutionary models. The dimensions of the Atapuerca lower and upper anterior teeth are also small in relation to the middle Pleistocene specimens and Krapina, but they are comparable to those of the late Pleistocene Neandertals, and there is certain expansion of the buccolingual dimensions of the upper lateral incisors with regard to early Homo . The anterior/posterior size pattern of variability observed in Atapuerca is discussed in terms of the different selective pressures which presumably operated over the anterior and posterior segments of the dentition. The multivariate tooth shape analysis indicates a relatively close relationship between Atapuerca and the Neandertals, though some significant differences between them were observed. The limited European middle Pleistocene dental fossil record does not permit a rigorous study of the relationships between Atapuerca and other European middle Pleistocene populations. However, the present evidence suggests that Atapuerca had an unique and probably derived pattern regarding dental dimensions. Furthermore, a great shape dissimilarity has been observed between Atapuerca and Zhoukoudian, which is mainly due to the anterior/posterior tooth size differences between both samples.

Human population differentiation in the peri-Baltic Mesolithic: the odontometrics of Oleneostrovskii mogilnik (Karelia)

Odontometric data are reported for Oleneostrovskii mogilnik, a Mesolithic cemetery in the Karelian USSR. Containing the skeletal remains of 148 individuals and dated to 7500b.p., it is the largest and oldest of the known peri-Baltic Mesolithic cemeteries. The dental data from this site are compared to those from Skateholm, where dental dimensions closely approximate the mean tooth sizes for all late Mesolithic European material. Olenii ostrov possesses a significantly smaller dentition, despite antedating the Skateholm sample by 1500 years. Geographic, archaeological, linguistic and ancillary dental data are discussed which argue strongly for the presence in Mesolithic northern Europe of at least two quasi-isolated human mating networks. One of these, documented by Olenii ostrov, may also represent the earliest evidence for the establishment in the taiga zone of populations whose descendants are the modern Saami (=”Lapps”).

A biomechanical analysis of the masticatory apparatus ofPtilodus(Multituberculata)

ABSTRACT This study investigates the biomechanics of dental function in Ptilodus (Multituberculata) through vector analysis of masticatory muscles and comparisons of mechanically relevant cranial and dental dimensions to extant functional analogues. To isolate function, feeding behavior is divided into incision, slicing-crushing, and grinding, and these activities are related to corresponding dental regions (incisors, premolars, and molars, respectively). Quantitative comparisons to living mammals are made with respect to inferred muscle vectors. The masticatory apparatus of Ptilodus appears to have been adapted for a variety of jaw movements, including powerful retraction during the grinding cycle (utilizing the posterior part of the temporalis muscle), and the generation of large bite forces at a variety of tooth positions. The lateral compression of p4 is one indication that resistant food objects were a dietary component. However, the size and orientation of the posterior surface of the mandibular con...

Some vertical lineaments of lip position

This study was performed to elucidate quantitatively upper lip-tooth-jaw relativity in the vertical dimension. Values for five linear dentolabial measurements were generated from male (n = 42) and female (n = 46) reference samples. In addition, three vertical skeletofacial dimensions and two vertical dental dimensions were recorded. A significant sexual dimorphism was found in the vertical lip-tooth-jaw relationship: the upper lip of the female subjects was positioned on average 1.5 mm more superiorly at maximum smile than the upper lip of the male subjects (p less than 0.01). High smile lines appeared to be a female lineament, and low smile lines appeared to be a male lineament. There was a significant sex difference in upper lip length: the male subjects exhibited a longer upper lip than the female subjects (p less than 0.001). The mean difference was 2.2 mm. A similarly significant male-female difference was seen in the skeletal maxillary height measurement: the male sample showed a 2.2 mm mean vertical maxillary increase over the female sample (p less than 0.001). Furthermore, a significant difference was found between the clinical crown height of the maxillary central incisors in the male and female subjects of comparable ages: the male group had longer central incisor crowns (p less than 0.01).

Tooth components of mandibular deciduous molars of Homo sapiens sapiens and Homo sapiens neanderthalensis: a radiographic study.

Tooth components of deciduous molars were measured from standardized radiographs of Homo sapiens sapiens and Homo sapiens neanderthalensis. Enamel height and width were greater in deciduous teeth of Homo sapiens sapiens than in Homo sapiens neanderthalensis and the differences were statistically significant (p less than 0.01). Dentin height showed no significant differences between the two groups, but enamel to floor of pulp chamber and pulp height and width dimensions were significantly greater in Homo sapiens neanderthalensis. Discriminant analysis carried out between groups, using deciduous tooth components, showed an accuracy of 98-100% for identification of Homo sapiens sapiens and 83-92% for identification of Homo sapiens neanderthalensis. The results obtained in this study on dental dimensions support the hypothesis of a distinct evolutionary line for Neanderthals.

FLUCTUATING ODONTOMETRIC ASYMMETRY, MORPHOLOGICAL VARIABILITY, AND GENETIC MONOMORPHISM IN THE CHEETAH ACINONYX JUBATUS.

The magnitudes of dimensional variability and fluctuating asymmetry in dental dimensions are reported for a sample of South African cheetah Acinonyx jubatus. To test the hypothesis that elevated levels of variability and asymmetry are associated with the increased developmental instability reported for this species, our results were contrasted to those for two other felids: Felis lybica and F. caracal. These findings suggest that dental dimensions in cheetahs are not significantly more variable or asymmetric. Hence, it is concluded that the cheetah may not be as developmentally unstable as was previously supposed.

Determinants of dental health behaviors in Nordic schoolchildren

As part of the comprehensive study "Health Behavior in Schoolchildren. A WHO Cross National Survey", this paper set out to identify determinants of four dental health behavioral dimensions in Finnish, Norwegian, and Swedish schoolchildren aged 11, 13, and 15. The data were collected by means of self-administered questionnaires, and the results are considered to be representative of each country. The total sample size approximated 3000 pupils in each country. The four dependent variables, fluoride, interdental cleaning, sugar, and brushing behavior, were all based upon sum-scores of several questions, and were subsequently regressed upon five predictors: school achievement, sex, time spent with friends, educational plans, and family meal pattern. This model provided a far better fit to the data on sugar and brushing behavior than to fluoride and interdental cleaning behavior. However, brushing seems to be different from sugar behavior, being influenced by different factors. While brushing is closely linked to the prevailing sex-role pattern, sugar behavior is stronger related to peer group norms. Thus, the symbolic function of sweet consumption of the youth culture should have implications for the design of intervention strategies. For example, the provision of alternative behaviors will only be successful if the behaviors serve the same function as sugar consumption.

Effects of Perinatal Alcohol Exposure and Dietary Calcium Supplements on Skeletal and Dental Growth in Rats

Osteoporosis, hypocalcemia and skeletal size reduction are all common correlates of perinatal alcohol exposure. The present study assesses the effects of dietary calcium supplements on reversing perinatal alcohol-induced osteopenia. One hundred and twenty-nine offspring from Fisher 344 rats received 14% v/v alcohol in tap water from conception to weaning or 3 months of age followed by dietary calcium supplements (230 mg/kg/day) to 6 months of age. Significant group effects (p less than 0.001) were noted for all 12 dental and skeletal dimensions measured. Results suggest that calcium therapy following perinatal alcohol exposure may ameliorate alcohol-induced osteopenia in exposed offspring.

Internal structure of prevention and dental health behaviors

Previous work investigating the internal structure of preventive health behavior (PHB) has not included a representative sample of dental health behaviors. Consequently, it has not been possible to evaluate whether dental dimensions of health behavior exist or whether dental behaviors are part of other health behavior dimensions. The results of a principal-components analysis of PHBs in which a larger sample of dental health behaviors is included shows that purely dental dimensions of health behavior emerge in a sample of 350 university students and faculty. Dental health behavior may need to be conceptualized as a dimension of health behavior separate from other PHBs.

A nonracial craniofacial perspective on human variation: A(ustralia) to Z(uni)

Dental and craniofacial measurements were collected for 57 samples from Asia, the Pacific, the aboriginal western hemisphere, and Europe. The craniofacial dimensions include many that are not obviously under the control of specific selective forces. Similar configurations for these in different samples should yield indications of recency of common ancestry according to the logic expressed by Darwin and evident in the relationships indicated by nuclear DNA comparisons. Dental dimensions, however, vary according to the length of time that different intensities in selective forces have been in operation. The craniofacial measurements were transformed into C scores and used to generate Euclidean distance dendrograms. When all the material was used to generate a single dendrogram, the European and Amerindian samples sorted into two regionally identifiable clusters, and the Asian and Pacific material sorted into the three clusters identified in separate previous studies: a Mainland Asian cluster, a Jomon-Pacific cluster and an Australo-Melanesian cluster. Since these clusters are based on variation in traits that are basically nonadaptive in nature, no hierarchical ranking is possible. The clusters simply reflect degree of relationship. This technique holds forth the promise of producing a nonracial assessment of the relationships of all the peoples of the world, past and present.

The taxonomy of savannah baboons: An odontomorphometric analysis.

The subgeneric relationships of savannah baboons have long been a point of contention among taxonomists. Recent documentation of morphological clines and evidence of interspecific hybridization have further complicated this problem. In this investigation, the dental dimensions of 443 savannah baboons, representing three of the generally recognized species, Papio anubis, P. cynocephalus, and P. ursinus, were analyzed using univariate and multivariate statistical procedures. A small number of possible P. ursinus/P. cynocephalus hybrids was included in the analysis. The results suggest that the three morphotypes are clearly distinct. Furthermore, the hybrid group possesses a dentition incorporating different elements of the two interbreeding species. However, these individuals are not simply intermediate but quite different. These findings, considered in conjunction with other morphological and distributional data, tend to warrant maintenance of the present specific distinctions.

Allometric scaling in palaeontology: A critical survey

Allometric scaling models, used to describe morphological and functional relationships between two sets of observations, are examined both in concept and in application. This paper focuses on the underlying assumptions and statistics of the methods most frequently used: linear regression, principal axis and standard major axis analysis. It is shown that the standard major axis (SMA) is the most appropriate bivariate linear model in palaeonotological research. Differences among the models discussed are illustrated by a morphometric analysis of dental dimensions in australopithecines.

Patterns of metric variability in the dentition of Papio ursinus.

The present investigation assesses a number of explanations for the patterns of variability in dental dimensions. Coefficients of variation were calculated for mesiodistal and buccolingual diameters in a sample of 105 Papio ursinus crania (52 male, 53 female). Variability profiles consisting of arrays of values of coefficients of variation were evaluated by means of Friedman's two-way analysis of variance and Kendall's coefficient of concordance. Although molar teeth were found to be the most dimensionally stable, our results failed to support either the morphogenetic field theory or the occlusal complexity hypothesis. The data presented here are generally supportive of Pengilly's phenotypic complexity theory. However, speciesspecific clustering patterns found in our regressions of dimensional variability on mean tooth size suggest that differences in variability levels might be related to differences in selective pressures.