Cranial Affinity Among Historical Populations in Sardinia, Italy: Biometric Insights for Orthodontic Purposes

doi:10.21203/rs.3.rs-2828516/v1

Download PDF

Article

Cranial Affinity Among Historical Populations in Sardinia, Italy: Biometric Insights for Orthodontic Purposes

https://doi.org/10.21203/rs.3.rs-2828516/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this latest preprint version

Since human skulls may be used as a benchmark of the evolutionary process, the aim of the present study to assess the cranial affinity of Sardinian populations from different historical periods with a standard index to evaluate its benefits for orthodontic purposes.

Craniometric variables from four throughout cephalograms (anterior and lateral) of 72 units from historical Sardinian populations, two prehistoric, one medieval, and one modern were compared to the Bolton standard. Anova-one way was performed for means comparison. Hierarchical cluster analysis and the bootstrap technique for the reliability of dendrogram were performed.

Length data pointed out statistically significant results (p < 0.01). Usually, the medieval showed higher mean values compared to the other groups; the prehistoric population presented the highest value of Euclidean distance when compared to the medieval; the modern showed no affinity to prehistoric populations nor to the Bolton standard. The length and the breadth of the neurocranium, maxillary-alveolar length, orbital height, maximum cranial breadth and palate breadth external contributed to the dissimilarity among populations.

Dissimilarities in the craniometric measurements of Sardinian populations are impressive. Therefore, the main outcome showed that the craniometric standards as the Bolton standard are not applicable across the Sardinian population.

Cranial bones measurements play a fundamental role in the analysis of skeletal variation¹. Several studies have assessed that skeletal measures are a combination of a continuous interaction between the genotype and the environment^2,3 with a coefficient of heritability around 0.50-0.70^4,5 in twins. In spite of this low level of heritability, the measurements of the skull are essential for physical anthropology having also several clinical applications, i.e. orthodontic diagnosis procedure⁶.

Morphologic differentiation is linked to genetics⁷, and genetic variation in different geographic groups of Homo sapiens is quite small, only 10% of the total^8,9.

The level of differentiation, regarding craniometric variables between the world geographic areas was assessed, underlying a substantial agreement between craniometric and genetic data^3,4,10−12.

A very evocative hypothesis suggests that some morphometric characteristics, like the width of the bizygomatic and the maxillary, might be the result of a particular behaviour and cultural attitudes, like the use of the "mouth-like third hand" in order to work skins and other instruments. These habits would have produced excessive masticatory stresses, inducing modifications in maxillo-facial anatomy¹³.

Geographic isolation might eventually have also contributed to maintaining such characteristics, as the morphologic model may be a consequence of climatic and biomechanical adaptations¹⁴. In Sardinia, several aspects of the morphological results were related to the geographic isolation, inbreeding, genetic drift, and probably the selection induced by specific environmental factors (e.g., endemic malaria) have contributed to the genetic diversification of Sardinians from mainland Italians and other populations¹⁵. One of the well-known genetic features of the Sardinian population is the high prevalence of β−thalassemia¹⁶, a hereditary disease of the erythropoietic system with specific maxillo-facial features (facies thalassemica), particularly widespread and deeply studied starting from the last decades^17,18.

European cranial samples were evaluated by several studies since the last decades of the 20th Century^3,19−21 with an overrepresentation of Central and Eastern Europe populations, while, Sardinia is underrepresented²².

The most comprehensive work about the somatic features of the ancient Sardinian populations considers eight human skulls from different periods, from the Neolithic (4700 − 4000 BC) until the Bronze Age (1300 − 1150 BC)²³. Evidence signals, thus, a Sardinian-specific pattern relative to the cranium morphology that may be determined from the Neolithic to the Bronze Age, where the genetic distances between the Sardinian population and other European populations were linked directly to the Neolithic and Bronze ages before the arrival of Romans and other invaders²⁴.

On this assumption, an observational study was designed to assess the cranial affinity of Sardinian populations from different historical periods with a standard index to evaluate its benefits for orthodontic purposes.

Length data pointed out statistically significant differences among groups (p < 0.01); the Medieval population, usually, showed higher mean values in comparison to other groups. Data referred to heights revealed statistical significance for Nasion-prosthion height (NPH) and Nasal height (NLH) variables, with lower mean values being observed in the Domus population. As regards the breadth measurements, statistically significant differences were observed for the variables Minimum cranial breadth (WCB), Biorbital breadth (EKB), Orbital breadth (OBB), and Nasal breadth (NLB). A progressive increment of WCB was detected through historical ages. The NLB had an unusual figure: Nuragici, Medieval and Modern groups showed similar values and only Domus significantly differed from the others (p < 0.01), showing the lowest values (Table 1).

Table 1

Comparison of craniometric variables with Howell’s Code²⁵ among the Sardinian population: mean and standard deviation (in brackets). Means differences assessed by Anova one-way analysis.
Craniometric Variable	Domus	Nuragici	Medieval	Modern	p-value
Basion-nasion length (BNL)	105.2 (5.2)	106.8 (4.2)	114.7 (6.5)	110.4 (6.1)	< 0.01
Basion-prosthion length (BPL)	99.2 (6.5)	102.2 (6.7)	109.3 (6.3)	107.3 (5.8)	< 0.01
Maxillary-alveolar length (MAL)	45.5 (4.7)	48.1 (4.5)	53.9 (4.6)	51.2 (4.0)	< 0.01
Nasion-prosthion height (NPH)	67.2 (3.5)	66.9 (1.9)	72.5 (4.5)	68.7 (5.1)	< 0.01
Orbital height (OBH)	31.8 (1.4)	31.2 (1.7)	32.7 (3.1)	33.4 (2.8)	0.30
Nasal height (NLH)	51.5 (2.8)	52.3 (1.0)	55.1 (3.6)	52.6 (3.4)	0.01
Maximum cranial breadth (XCB)	143.0 (7.0)	140.8 (4.4)	145.9 (7.9)	147.6 (5.9)	0.15
Minimum cranial breadth (WCB)	104.0 (3.3)	105.2 (1.1)	111,8 (5.7)	110.1 (5.9)	< 0.01
Maximum frontal breadth (XFB)	118.9 (5.4)	115.3 (2.3)	120.4 (6.8)	118.2 (7.0)	0.39
Biorbital breadth (EKB)	102.9 (3.6)	101.0 (2.1)	111.9 (5.5)	106.8 (10.0)	< 0.01
Bizygomatic breadth (ZYB)	136.0 (7.8)	130.9 (4.9)	138.2 (6.7)	139.6 (5.7)	0.06
Bimaxillary breadth (ZMB)	96.3 (3.1)	96.0 (1,2)	98.1 (5.3)	98.5 (3.4)	0.46
Orbital breadth (OBB)	40.2 (2.0)	40.6 (2.8)	43.3 (2.3)	41.5 (1.9)	< 0.01
Nasal breadth (NLB)	23.5 (1.9)	26.1 (0.7)	26.9 (2.3)	25.9 (2.3)	< 0.01
Palate breadth external (MAB)	64.7 (3.9)	63.7 (3.8)	65.7 (5.4)	67.0 (6.7)	0.58
Anterior-posterior nasal spine	48.4 (5.4)	47.1 (7.4)	53.9 (5.2)	57.2 (5.0)	< 0.01
Intraorbital breadth	27.6 (2.9)	26.2 (3.0)	29.4 (3.2)	28.4 (1.9)	0.08
Alveolar spinal height	17.5 (1.5)	17.0 (1.8)	18.5 (3.3)	19.6 (1.8)	0.07
Minimum alveolar height	42.4 (2.4)	42.2 (0.5)	43.6 (7.4)	44.0 (3.9)	0.85
Prosthion total angle	89.6 (1.8)	91.0 (5.0)	93.7 (5.8)	92.0 (4.3)	0.16
Prosthion nasal angle	91.5 (2.6)	93.0 (4.8)	91.6 (7.2)	93.4 (3.7)	0.57

The Domus sample showed high values of distance to the Medieval population (544.7) and to the Modern one (330.6). The Modern population showed no similarity to prehistoric populations nor to Bolton’s standard. Similar results were obtained using the bootstrap technique on the original data set, without Bolton’s standard, allowing us to build up the means and standard errors after 500 iterations for each variable (Table 2).

Table 2

Squared Euclidean Dissimilarity Coefficient Matrix obtained for the populations
	Medieval	Bolton¹	Modern	Nuragici
Bolton¹	603.8
Modern	117.2	293.4
Nuragici	545.0	253.8	379.9
Domus	544.7	279.8	330.6	87.3
¹ Bolton values were used as a reference

Similar results of UPGMA were obtained using the bootstrap technique on the original data set, without Bolton’s standard, allowing us to build up the means and standard errors after 500 iterations for each variable (Table 2,3).

Table 3

Squared Euclidean Dissimilarity Coefficient Matrix after 500 bootstrapped iterations below diagonal and relative standard errors, above diagonal, for the populations.
	Medieval	Modern	Nuragici	Domus
Medieval	-	.0003	.0011	.0005
Modern	115.9	-	.0009	.0004
Nuragici	544.9	379.9	-	.0005
Domus	544.7	330.6	87.3	-

The similarity among populations is immediately appreciable from the dendrogram (Fig. 1).

A heed emerging from the view tree is the clear differentiation in two clusters separated by Bolton’s standard; Nuragici and Domus at the top and Medieval and Modern at the bottom.

Figure 2 displays the D-plot of the first two principal coordinates derived from Principal Component Analysis (PCA). The first two eigenvalues collectively account for 80.9% of the total variance (59.1% and 21.8%, respectively).

Clearly, Domus and Nuragici populations tend to form separate clusters. The goodness of fit was high (≥0.75) for Bolton, Medieval and Nuragici, and medium-high (0.5–0.75) for the other groups.

The length and the breadth of the neurocranium, Basion-nasion length (BNL), and Basion-prosthion length (BPL), highly contribute to the first principal component. The variance along the second axis was principally generated by Maxillary-alveolar length (MAL), Orbital height (OBH), Maximum cranial breadth (XCB) and Palate breadth external (MAB) positive sense, Maximum frontal breadth (XFB), EKB and OBB, negative sense. BNL, BPL and XFB clearly separate between groups (Domus and Nuragici versus Modern and Medieval), the former with a large frontal, biorbital and orbital breadth, the latter with a longer and narrower skull pattern (BNL and BPL).

The first component places the Domus close to the Nuragici population (negative sense) and separates them from Modern basically due to BNL, MAL, OBH, XCB, WCB, EKB, ZMB, and MAB.

Craniometric data in biological anthropology have a long tradition and have been utilized in a variety of studies, particularly in the last decades of the 20th Century. The majority of the studies focus on the reconstruction of prehistoric human populations^21,26−28 or on the diversity of the human species in regard to the evolution of modern humans developing the idea that the patterns of variation seen in human cranial data can be generalized to patterns of genetic variation. In other words, cranial data are often utilized as a proxy to understand genetic similarity or dissimilarity between human groups, past and present.

The skulls of the different Sardinian populations exhibit several specific morphological phenotypes and the prehistoric skulls show peculiar morphological features such as a minimum cranial width and orbital width lower than the other Sardinian populations. The multivariate analysis allows to partition the amount of phenotypic variation acting on the four populations studied. Probably, the distinctive features of the Domus sample have been diluted by historical and population exchange. This differentiation can be described as the contribution of foreign genes and morphologies in the last two groups (Medieval and Modern). Both cluster view and PCA showed that Bolton's standard is exactly opposite to the Sardinian Fig. 2⁹.

The cluster of prehistoric populations (Domus and Nuragici), and the observed morphometric boundary between neighbouring populations also suggest a sharp genetic boundary between these two groups. The remaining populations are grouped separately from each other. In UPGMA analysis of the bootstrapped values, Modern and Medieval samples are far away. This may be the consequence of the cultural development and evolution of the two populations. The isolation of Sardinia even during the Roman, Visigoth, Arabian, Catalan and Italian conquests could have preserved morphological characteristics arising during the Neolithic and pre-Neolithic Ages. The results indicate that the differences observed in craniometric data and the dissimilarities are all part of the general range of variation among Mediterranean populations³⁰, although Sardinian samples should be included in the gracile Mediterranean type³.

The cranial evolution of Sardinians from Neolithic to modern times seems to show some kind of temporal continuity with the Neolithic groups³¹. Furthermore, our results evidence that Bolton’s indices are not a good standard for the Sardinian population and so are not helpful in clinical practice likewise orthodontic diagnosis. One possible explanation that Bolton’s standards don’t belong to Sardinian figures is the genetic variability within the Sardinian population itself when are studied the distributions of various markers in different historical/geographical areas²³.

In the literature seems that Bolton's standards apply to patients with ideal occlusion standards that could be similar for different populations, but various ethnic groups may be characterized by a different prevalence of Bolton discrepancy³².

Although skull morphology is affected to some extent by environmental factors and is under lower genetic control, it is accepted that craniometric traits are phylogenetically informative.

The results improve the ability to make inferences for the assessment of cranial variation in the Sardinian population, even if the analysis included a small cranial sample. Combining quantitative genetic methods with geometric morphometric tools³³, it is possible to construct a Sardinian version of Bolton's standards for the different craniofacial characteristics of the island population. These differences should be taken into account when developing an individualised orthodontic treatment plan.

Study planning

The study was planned in collaboration with the Soprintendenza Archeologia, Belle Arti e Paesaggio for the provinces of Sassari, Olbia-Tempio and Nuoro. The latter contributed to the location of the archaeological sites to be included and also provided the skulls object of the study. The present study did not require ethical approval for its observational design according to the Italian law (Gazzetta Ufficiale n. 76 dated 31 March 2008).

Study setting

The study was conducted in Sardinia, the second-largest island in the Mediterranean Sea. It is well known that Sardinia was probably the first Mediterranean island to be populated (with a pre-Neolithic date around 9100 years BC), and for developing a unique megalithic culture, the Nuragic culture, which lasted in the island from the Middle Bronze Age up to the Roman colonization (1500 − 400 BC)³⁴.

After the Phoenicians, Sardinia was partially conquered or visited by the Romans, the Vandals, the Byzantines, the Arabs, the Catalans, and the Italians. As evidence, there are several sites of archaeological interest scattered throughout the entire region³⁵.

Moreover, owing to its insularity, the region lends itself very well to observational investigations and represents an excellent test case in relation to the reported dynamics. In particular, the island has already been shown to be well suited to epidemiological studies, as it protects the region from interference caused by territorial contiguity. As such, it can serve as an excellent training ground for the reported genetics and epidemiological dynamics.

Selection of the sample

The population investigated covers different historical eras represented by historical and prehistoric periods (the best represented being the middle-age and modern times), accounting for about 4000 years of Sardinian history. Within this period there have been several invasions and movements of people from Africa and other parts of Europe. Only undamaged skulls from burials in cemeteries were considered. All the skulls belonged to adult humans. Typically, intraspecific variation related to sexual dimorphism is included in this area of research³⁶. As no report is available on variation between the populations studied, to avoid this source of variation between groups, the sexes of the populations studied were balanced wherever possible. Otherwise, it is likely that the natural adult gender ratio was close to one-to-one, so the observed variation in analysis can be attributable essentially to the group-related interspecific source. Seventy-two units were considered. In particular, 42 skulls cleaned up and classified using the methods suggested by Parzianello³⁷ were included.

Figure 3 reports the geography of cemeteries burials where skulls were excavated:

− 12 skulls of pre-historical populations: 8 crania founded in the Domus de Janas (III millennium BC) and 4 crania founded in Tomba dei Giganti of the nuragic culture (II millennium BC);

− 30 skulls of the late-Medieval population were founded in the cemetery of the village of Geridu (X-XI century).

Finally, craniometric measurements of the Modern Sardinian population were carried out on 30 subjects at the X-rays service of the Dental Institute of the University of Sassari.

Craniometric measurements

Two cephalograms (anterior and lateral) were obtained by each skull, following the technique described by Broadbent³⁸ using radiographic equipment (Orthophos SL 3D Orthophos 5/plus^®, Sirona, Germany machine code D3297). The measurements were carried out following the Munich international convention.

Fifteen craniometric variables were measured following the method of Howells²⁵; other six craniometric measures of specific orthodontic interest were also obtained (Table 1).

Bolton’s standard values were used as a reference³⁹. The selection of undamaged skulls allowed us to have no missing data.

A well-trained dentist performed all measurements. To quantify the bias of the method, two repeated measurements were made on eight variables over a 72-hour period, and the reliability of the mean values of three random craniometric measurements obtained from lateral radiographs was evaluated as percent agreement (Table 4).

Table 4

Percent agreement of the measurement.
Measurement	Howell's code	1st measurement	2nd measurement	Agreement (%)
Basion-nasion length	BNL	109.2	109.8	99.5
Basion-prosthion length	BPL	111.2	110.9	99.7
Maxillary-alveolar length	MAL	52.7	53.6	98.3
Nasion-prosthion height	NPH	68.6	68.7	99.9
Nasal height	NLH	31.0	29.7	95.8
Minimum alveolar height		44.4	43.7	98.4
Orbital height	OBH	31.0	29.6	95.5
Nasal breadth	NLB	19.3	19.1	99.0

Statistical analysis

Data were tabulated in a Microsoft Excel worksheet and the analysis of the data was performed using SPSS software version 28:0 for Mac. The results of the craniometric measurements are given as mean and standard deviation, Anova one-way analysis was used for means comparison among the four populations. The statistically significant level was set up at α = 0.01. Hierarchical cluster analysis was performed from the squared Euclidean distance matrix via Unweighted Pair Group Method using the arithmetic Average (UPGMA) using R version 4.1.3. The reliability of dendrograms was investigated using the bootstrap technique⁴⁰ via a re-sampling with a replacement procedure from an already-drawn sample. Another cluster analysis (UPGMA) using the mean values of the bootstrapped variables (500 iterations) was also computed. Principal Components Analysis (PCA) was also carried out.

Data Availability Statement

The datasets generated during and/or analysed during the current study are available from the corresponding author upon reasonable request.

Methods Statements

All methods were carried out in accordance with the Italian relevant guidelines and regulations (https://www.gazzettaufficiale.it/eli/gu/2008/03/31/76/sg/pdf).

The study proposal was submitted to the Ethical Committee, following the Italian legislation, the research group must submit the research proposal to the Ethical Committee; The experimental protocols may start after 60 days, even without a proper reply of the Ethical Committee as the study was designed as a cross-sectional evaluation.

Additional Information
The authors declare no competing interests.

Ulcay, T., Kamaşak, B. Evaluation of craniometric measurements in human skulls. J HealthSci Med.4(1), 38-44. doi: DOI: 10.32322/jhsm.804341 (2021).
Susanne, C. Genetic and environmental influences on morphological characteristics. Ann Hum Biol. 2, 279– 287. doi:10.1080/03014467500000851 (1975).
Lalueza Fox, C., Gonzalez, M.A., Vives, C.S. Cranial Variation in the Iberian Peninsula and the Balearic Islands: Inferences about the History of the Population. Am J Phys Anthr. 99, 413-428. doi:10.1002/(SICI)1096-8644(199603)99 (1996).
Relethford, J.H. Craniometric variation among modern human population. Am J Phys Anthr. 95, 53-62. doi:10.1002/ajpa.1330950105 (1994).
Konigsberg, L.W. Quantitative variation and genetics. In: An Evolutionary and Biocultural Perspective. New York: Wiley-Liss 135-162. (2000).
Zhe-Bin, Yan., Yi-Dan, Wan., Chu-Qiao, Xiao., et al. Craniofacial Morphology of Orthodontic Patients with and without Temporomandibular Disorders: A Cross-Sectional Study. Pain Res Manag.2022, 9344028. doi:10.1155/2022/9344028 (2022).
Martínez-Abadías, N., Esparza, M., Sjøvold, T., González-José, R., Santos, M., Hernández, M. Heritability of human cranial dimensions: comparing the evolvability of different cranial regions. J Anat.214(1), 19-35. doi:10.1111/j.1469-7580.2008.01015.x (2009).
Nei, M., Roychoudhury, A.K. Genetic relationship and evolution of human races. J Evol Biol.14, 1-59. Doi:10.1007/BF01908190 (1982).
Howells, W.W. Introduction. In: Multivariate statistical methods in physical anthropology. Dordrecht Holland. (1989).
Bertranpetit, J., Cavalli-Sforza, L.L. 1991 A genetic reconstruction of the history of the population of the Iberian Peninsula. Ann Hum Genet.55(1), 51-67. doi: 10.1111/j.1469-1809.1991.tb00398.x (1991).
Cavalli Sforza, L.L., Menozzi, P., Piazza, A. History and geographic of human genes. Princeton University Press. Princeton (1994).
Hernàndez, M.C., Lalueza Fox, C., Garcia Moro, C. Fuegian cranial morphology. The adaption cold harsh environment. Am J Phys Anthr. 103, 103-117. doi:10.1002/(SICI)1096-8644(199705)103:1 (1997).
Pacey, L. Mouth used as third hand by cavemen. Br Dent J.213, 336. doi.org/10.1038/sj.bdj.2012.902 (2012).
von Cramon-Taubadel, N. Evolutionary insights into global patterns of human cranial diversity: population history, climatic and dietary effects. J Anthropol Sci.92, 43-77. doi: 10.4436/jass.91010 (2014).
Chiang, C.W.K., Marcus, J.H., Sidore, C. et al. Genomic history of the Sardinian population. Nat Genet. 50, 1426–1434. doi.org/10.1038/s41588-018-0215-8 (2018).
Sardinia council. L'incidenza delle talassemie. Available online : https://www.sardegnasalute.it/index.php?xsl=313&s=36635&v=2&c=2942#:~:text=In%20Italia%20le%20regioni%20pi%C3%B9,ed%20in%20Sardegna%20circa%201.000 (Accessed on 15 April 2023).
Martini, M., Tornali, C., Bragazzi, N.L., Paluan, F., Vardeu, M.F. The History of Beta Thalassaemia in Sardinia: The Contribution of the Italian Schools of Pediatrics. Acta Med Hist Adriat.17(1), 65-90. doi: 10.31952/amha.17.1.4 (2019).
Rösing, F.W., Schwidetzky, I. Vergleichend-statistiche Untersuchungen zur Anthropologie des frühen Mittelalters (500-1000 n.d.Z.). Homo.28, 65-115. (1977).
Rösing, F.W., Schwidetzky, I. Vergleichend-statistiche Untersuchungen zur Anthropologie des frühen Mittelalters (500-1000 n.d.Z.). Homo. 132, 211-251. (1981).
Schwidetzky, I., Rösing, F.W. Vergleichend-statistiche Untersuchungen zur Anthropologie der Neuzeit (nach 1500). Homo.35, 1-49. (1984).
Sokal, R.R., Uytterschaut, H. Cranial variation in European populations: a spatial autocorrelation study at three time periods. Am J Phys Anthr. 74, 21-38. doi:10.1002/ajpa.1330740103 (1987).
D’Amore, G., Di Marco, S., Floris, G., Pacciani, E., Sanna, E. Craniofacial morphometric variation and the biological history of the peopling of Sardinia. Homo. 61(6), 385-412,. doi.org/10.1016/j.jchb.2010.09.002 (2010).
Vona, G. The peopling of Sardinia (Italy): history and effects. Int. J. Anthropol.12, 71–87. doi.org/10.1007/BF02447890 (1997).
Marcus, J.H., Posth, C., Ringbauer, H., et al.. Genetic history from the Middle Neolithic to present on the Mediterranean island of Sardinia. Nature Commun. 11, 1. doi:10.1038/s41467-020-14523-6 (2020).
Howells, W.W. Cranial variation in man: a study of multivariate analysis of patterns of difference among recent human populations. Peabody Museum Papers.67, 1-259. (1973).
Carlson, D.S. Temporal variation in prehistoric Nubian crania. Am J Phys Anthr. 45, 467-484. doi:10.1002/ajpa.1330450308 (1976).
Key, P., Jantz, R.L. A multivariate analysis of temporal change in Arikara craniometrics: a methodological approach. Am J Phys Anthr. 55, 247-259. doi:10.1002/ajpa.1330550213 (1981).
Jantz, R.L., Owsley, D.W. Variation among early North American crania. American Am J Phys Anthr. 114, 146-155. doi:10.1002/1096-8644(200102)114 (2001).
Farouk, A.H., Raafat, E.M., El-Awady A.A., et al. Digital evaluation of Bolton's tooth size discrepancies among different malocclusions categories of Egyptian adolescent orthodontic population: A retrospective study. Int Orthod.20(3), 100660. doi.org/10.1016/j.ortho.2022.100660 (2022).
Relethford, J.H. Global analysis of regional differences in craniometric diversity and population substructure. Human Biol. 73, 629-636. (2001).
Marcus, J.H., Posth, C., Ringbauer, H. et al. Genetic history from the Middle Neolithic to present on the Mediterranean island of Sardinia. Nat Commun. 11, 939. https://doi.org/10.1038/s41467-020-14523-6 (2020).
Kansal, A., Kittur, N., Kanhoba Mahabaleshwar, K. Analysis of Bolton's ratio among different malocclusion groups: A hospital based study. Ind J Dent.3, 139–144. 10.1016/j.ijd.2012.03.015 (2012).
Klingenberg, C., Leamy, L., Routman, E., Cheverud, J. Genetic architecture of mandible shape in mice: effects of quantitative trait loci analyzed by geometric morphometrics. Genetics157, 785–802. doi: 10.1093/genetics/157.2.785 (2001).
Unesco. Nuragic monuments of Sardinia. Available online: https://whc.unesco.org/en/tentativelists/6557/ (Accessed on 15 April 2023).
Geo Portale Nurnet. Available online: http://nurnet.crs4.it/nurnetgeo/ (Accessed on 15 April 2023).
Pan, R., Oxnard. C.E. Craniodental variation among Macaques (Macaca), nonhuman primates. BMC Evol Biol. 2: 1-12. doi.org/10.1186/1471-2148-2-10 (2002).
Parzianello, L.C, Machado Da Silveira, M.A., Furuie, S.S. Palhares, F.A.B. Automatic detection of the Craniometric Points for Craniofacial Identification. Anais do IX SIBGRAPI 189-196. (1996).
Broadbent, H.B. A new x-ray technique and its application to orthodontia. The Angle Orthodontist1, 45-66 (1931).
Broadbent, H.B., Broadbent, H.B., Golden, W.H. Bolton standards of dentofacial developmental growth. Saint Luis Missouri, The C.V. Mosby Company. (1975).
Efron, B. CBMS-NSF Regional Conference Series in Applied Mathematics. The Jackknife, the Bootstrap and Other Resampling Plans. SIAM Philadelphia. doi.org/10.1137/1.9781611970319 (1982).

No competing interests reported.

Download PDF

Version 1

posted

You are reading this latest preprint version

Cranial Affinity Among Historical Populations in Sardinia, Italy: Biometric Insights for Orthodontic Purposes

Status:

Version 1

Abstract

Figures

Introduction

Results

Discussion

Strengths and weaknesses of the study

Methods

Study planning

Study setting

Selection of the sample

Craniometric measurements

Statistical analysis

Declarations

References

Additional Declarations

Status:

Version 1