Hypodontia and retention of third molars in Norwegian medieval skeletons: dental radiography in osteoarchaeology.

OBJECTIVES: The objective of the present study is to compare the prevalence of third molar hypodontia in matched medieval and modern Norwegian sample with the aim to examine whether there are secular changes in dental anomalies. A second objective is to determine the level of primary retention of third molar in the medieval sample. MATERIAL AND METHODS: The medieval material consisted of 130 adult skulls, hypodontia of third molars was determined using radiography and compared to findings with panoramic film images of 400 15-year-old individuals from a contemporary Norwegian epidemiological study. RESULTS: Among 130 medieval skulls, hypodontia of third molar was found in 36 skulls (27.7%), and in the contemporary sample, hypodontia of third molar was found in 69 individuals (17.2%). Female predominance, although not statistically significant, was observed both in the medieval and in the contemporary group. The third molars showed absence in the mandible (21.5%) more often than the maxilla in the medieval sample, and in both jaws (11.2%) in the contemporary material. In the medieval sample, only 7.7% of the individuals had at least one retained third molar. CONCLUSION: No increase in the frequency of third molar hypodontia was found from the medieval period until today. The frequency of retained third molars seems to have increased from the medieval period to modern times. The use of radiographic examination in addition to macroscopic inspection can give us a better understanding of the aetiology on a number of conditions in human skeletal remains.

Extending Genome-Wide Association Study Results to Test Classic Anthropological Hypotheses: Human Third Molar Agenesis and the "Probable Mutation Effect".

A genome-wide association study (GWAS) identifies regions of the genome that likely affect the variable state of a phenotype of interest. These regions can then be studied with population genetic methods to make inferences about the evolutionary history of the trait. There are increasing opportunities to use GWAS results-even from clinically motivated studies-for tests of classic anthropological hypotheses. One such example, presented here as a case study for this approach, involves tooth development variation related to dental crowding. Specifically, more than 10% of humans fail to develop one or more permanent third molars (M3 agenesis). M3 presence/absence variation within human populations has a significant genetic component (heritability estimate h 2 = 0.47). The evolutionary significance of M3 agenesis has a long history of anthropological speculation. First, the modern frequency of M3 agenesis could reflect a relaxation of selection pressure to retain larger and more teeth following the origins of cooking and other food-softening behaviors (i.e., the genetic drift hypothesis or, classically, the "probable mutation effect"). Alternatively, commensurate with increasing hominin brain size and facial shortening, M3 agenesis may have conferred an adaptive fitness advantage if it reduced the risk of M3 impaction and potential health complications (i.e., the positive selection hypothesis). A recent GWAS identified 70 genetic loci that may play a role in human M3 presence/absence variation. To begin evaluating the contrasting evolutionary scenarios for M3 agenesis, we used the integrated haplotype score (iHS) statistic to test whether those 70 genetic regions are enriched for genomic signatures of recent positive selection. None of our findings are inconsistent with the null hypothesis of genetic drift to explain the high prevalence of human M3 agenesis. This result might suggest that M3 impaction rates for modern humans do not accurately retrodict those of the preagricultural past. Alternatively, the absence of support for the positive selection hypothesis could reflect a lack of power; this analysis should be repeated following the completion of more comprehensive GWAS analyses for human M3 agenesis.

Foot polydactyly and bipartite medial cuneiform: A case of co-occurrence in a Celtic skeleton from Verona (Italy).

We report a case of bilateral foot polydactyly and bipartite medial cuneiform in a male individual buried in a Celtic/Roman necropolis (3rd to 1st century BCE) in the city of Verona (Italy). During the construction of an underground garage in the main courtyard of the Bishop's Seminary at Verona between 2005 and 2010, archaeologists uncovered the remains of 174 individuals (108 non-adults and 66 adults). It is thought that these graves could belong to some of the first inhabitants of the urban area of Verona. The individual presented here (US 2807) is a middle-aged male (40-50 years) in a good state of preservation. His estimated stature is 1756 mm (± 32.1 mm). This male presents congenital anomalies in the feet and dental agenesis. We believe this to be the only known archaeological case of bilateral postaxial polydactyly with forked (Y) shape, in which both fifth metatarsals are associated with complete bipartition of the left medial cuneiform and partial bipartition of the right one. Polydactyly is fairly common in modern clinical cases but bipartite medial cuneiform is relatively rare; neither of these congenital conditions is well documented archaeologically.

Orthodontic anomalies and malocclusions in Late Antique and Early Mediaeval period in Croatia.

OBJECTIVE: Malocclusions are relative infrequently analysed in bioarchaeological investigations and if investigated the samples are very small. This research provides analysis of orthodontic anomalies of even 1118 individuals from the Late Antique (LA) and Early Mediaeval (EM) period. Aims were to describe the prevalence of orthodontic anomalies in this historical period and to analyse which orthodontic anomalies are best suitable for bioarchaeological investigations. METHODS: 1118 skulls were examined for anomalies of tooth number, tooth displacement (rotation, malposition, diastema and crowding) as well as for malocclusions. RESULTS: The prevalence of hypodontia in the LA was 41.02% and 30.61% in the EM sample. Tooth displacement was noticed in 15.63% individuals from the LA and in 12.42% individuals from EM. About 26% of the LA sample and 7.19% of the EM sample were affected with tooth crowding and the difference was statistically significant. CONCLUSION: Orthodontic anomalies affecting only one tooth or group of teeth are more suitable for examination in bioarchaeological investigations than orthodontic features requiring presence of both jaws and all or almost all teeth. Clinical investigation protocols and methodology should be adopted for bioarchaeological researches and international standards and recommendations should be established for this kind of investigation on skeletal remains.

Erupción y retención del tercer molar en jóvenes entre 17 y 20 años: Antofagasta, Chile / Eruption and retention of third molars in young people between 17 and 20 years of age: Antofagasta, Chile

La retención intraósea y la erupción en malposición de 3Ms han sido muy estudiadas. Son causadas, probablemente, por disminución del tamaño de maxilares por cambios de hábitos alimentarios, reduciendo el espacio retromolar, lo que dificulta la erupción normal entre 15 y 25 años de edad, y produce patologías o molestias por comprometer estructuras orofaciales próximas. Lo anterior, ha promovido la exodoncia profiláctica u ortodóncica, incluso del germen dentario, con altos costos clínicos, hospitalarios, laborales, comprometiendo parte de los recursos destinados a financiar otros procedimientos quirúrgicos orales, además de riesgos durante cirugía, postoperatorio y lesiones iatrogénicas temporales o permanentes. La muestra consistió en 100 jóvenes de 17 a 20 años de edad (50 mujeres y 50 hombres) de la ciudad de Antofagasta, sanos, sin malformaciones general y maxilofacial, sin haber presentado enfermedades infecciosas que alteraran odontogénesis y períodos eruptivos, sin exodoncias de 3M ni tratamientos ortodóncicos previos al examen de la radiografía panorámica y clasificando erupción de 3Ms según tablas de Pell-Gregory y Winter. Se determina 49,1 por ciento de 3Ms retenidos con p<0,05 significativo respecto dientes erupcionados, predominando retención maxilar, especialmente en mujeres. En todos los casos y en mandíbula predominan 3Ms con impactación mesioangulada (p<0,05 significativa) y en maxilares la retención vertical (p<0,05 de significancia). Prevalecen 3Ms distoangulados en maxilares, posición que predispone a complicaciones operatorias y postoperatorias en exodoncias. La retención horizontal se aprecia en mandibula, siendo el segundo tipo de retención (21,5 por ciento en toda la muestra y 30 por ciento en hombres). Sin una decisión clínica que indique la cirugía, se sugiere postegar la exodoncia profiláctica de 3Ms, esperando posible erupción tardía (Hattab, 1997; Ventã et al. 1999, 2004 y Kruger et al.). Meta-análisis demuestra: mínima morbilidad...

Intraoseous retention and anomalous eruption position of 3Ms had been widely studied. They are probably produced by reducing the size of jaws by changes in eating habits, reducing the retro molar space, making it difficult normal eruption between 15 and 25 years old, producing pathologies or discomfort by compromising nearly orofacial structures. The above, has promoted the extraction or prophylactic orthodontic, even from the dental germ, with expensives clinical cost, hospital surgery, compromising part of the resources to finance other surgical oral procedures, in addition to risks during surgery, postoperative and iatrogenic injuries temporary or permanent. The sample consisted in 100 young people aged 17 to 20 years of age (50 women and 50 men) of the city of Antofagasta, healthy, without general and maxillofacial malformation, without having submitted infectious diseases that distort odontogenesis and periods of eruption, without extractions of 3M nor orthodontic treatments prior to the examination of the x-ray overview and classifying eruption of 3Ms as tables of Pell-Gregory and Winter. It was determined that 49.1 percent of 3Ms were retained, with p<0.05 significant with regard to erupted teeth, predominate maxillary retention, especially in women. In all cases and in maxilla predominate 3Ms with mesiangular position (p<0.05 of significance) and in maxillary vertical retention (p<0.05 of significance). Prevailing 3Ms maxilla with distoangular position, a position that predisposes surgical complications and postoperative extractions. The horizontal retention is apparent only in mandible, being the second type of retention (21.5 percent in all cases and 30 percent in men). Without a clinic decision to indicate surgery, we suggest to postpone the prophylactic extraction of 3Ms, awaiting possible late eruption (Hattab, 1997; Ventã et al., 1999, 2004; Kruger et al., 2001). Meta-analyzes show minimum morbidity in 3Ms extractions in...

A case of canine hypodontia in an early Croatian cemetery Strance-Gorica.

In the old Croatian cemetery Strance-Gorica in the Vinodol region, dating from the 9th to 11th century, osteological parts of the upper and the lower jaws with teeth were found, besides some other archeological finds. Data processing in dentistry regarding a possible presence of hypodontia was carried out on archeological finds (skeletal remains) on 27 persons available for the research. Only one case of canine hypodontia was found and described. In the remaining 26 persons no case of hypodontia was found on the relicts of the upper and lower jaws nor in other teeth groups. The frequency of hypodontia in the old Croatian cemetery Strance-Gorica was 3.7, which corresponds to the frequency of this anomaly in the 20th century population of Croatia.

Missing lateral incisors in Iron Age South-East Asians as possible indicators of dental agenesis.

The absence of lateral incisors is generally a reflection of agenesis or hypodontia, with a significant genetic basis and possibly environmental influence on the phenotypic expression. A human skeletal sample from the Iron Age cemetery of Noen U-Loke in Thailand has a very high prevalence at 79% of adults (30/38) with at least one incisor missing in either maxilla or mandible. If the cause of this high rate is genetic, it may be indicative of homogeneity, and, therefore, endogamy and probably isolation, of the population represented. Supporting agenesis as the explanation for this is the lack of space between the central incisors and canines in more than half the cases. An alternative explanation is that the teeth may have been lost during life through pathology or deliberate removal (ablation). There is no evidence in the form of remodelled lesions for pathological loss of the teeth. Although there were no significant differences between males and females in the numbers of teeth missing, there were significant differences in the patterns of loss, with males having more missing teeth on the right and females more on the left. No evidence was found in the clinical literature of agenesis involving side preference by sex, so this may indicate deliberate removal of the teeth. Males were also more likely than females to have no space for the missing teeth. Ablation of teeth has been recorded in other prehistoric South-East Asian populations but in these cases the evidence was much clearer. Agenesis seems to offer the most likely explanation for the missing teeth at Noen U-Loke and if so, indicates that a small, isolated population may develop a very high rate of hypodontia, with a side preference dependent on sex.

The effects of dental wear on third molar eruption and on the curve of Spee in human archaeological dentitions.

The abrasiveness of food is a key determinant in the rate of physiological attrition (dental wear) in humans. With increasing food processing through time, the rate of physiological dental wear in human teeth has decreased markedly. Many consider such wear to be beneficial to oral health and that insufficient wear may result in impaction of the third molars. If enhanced extraoral food processing provides an evolutionary advantage, then it is possible that agenesis of the redundant third molar may follow. One of the aims here was to examine impaction and agenesis of the third molars in four populations of varying antiquity and hence varying dental-wear rates. Paradoxically, whilst there is a decrease in the rate of dental wear with modernity, there is also an increasing prevalence of advanced dental wear due to prolongation of the lifespan of the human dentition. As the effect of dental wear on the curve of Spee was unknown, a second aim was to examine it in an archaeological population with a high rate of dental wear. The results showed an increase in non-eruption and impaction of the third molars with modernity, but did not demonstrate a significant increase in the rate of agenesis. The time period over which impaction and agenesis could be discerned was of the order of 600 years and this may not be sufficient to observe adaptive changes at the genetic level in humans. In molar teeth there was no clear indication of maintenance of the curve of Spee with dental wear. This has potential implications on the design of prostheses for the worn dentition.

Congenital absence of permanent second molars.

During the last eight years, Canterbury Archaeological Trust has excavated over 1,600 articulated human skeletons from sites under threat of redevelopment in Kent. The recovered material, ranging in date from prehistoric to Victorian, provides a unique corpus for the study of disease and abnormalities in earlier societies.

Agenesis of permanent incisors in a mediaeval maxilla and mandible: aetiological aspects.

A paleopathological maxilla and mandible with tooth agenesis were analyzed, focussing on the aetiology of the condition. The jaw material, derived from an adult mediaeval male, was examined by standard anthropological analyses, including radiography. In the maxilla there was agenesis of three permanent incisors and one premolar, and in the mandible of one permanent incisor and two permanent molars. Absence or marked reduction of the incisive foramen and the nasopalatine canal was found. The premaxillary area was reduced without general alveolar bone resorption. The pattern of tooth agenesis was similar to the pattern observed in contemporary individuals, except for the agenesis of one permanent maxillary central incisor. It is suggested that the pronounced lack of teeth in the maxillary anterior region is connected with deficient development of the premaxillary area of the nasopalatine canals and the incisive foramen. As the condition can be ascribed to deviations in the prenatal development, this investigation shows that embryological developmental patterns, which form the basis for the pattern of tooth agenesis, should be taken into account when evaluating dry bone pathology.

The human incisal suture and premaxillary area studied on archaeologic material.

The purpose of this study was to investigate the extent of the incisal suture, the size of the premaxillary area, and the developmental status of the dentition. Sixty-three medieval crania were examined: 30 from children and 33 from adults, including 5 cases with tooth deviations. All crania were photographed at a 1:1 scale. From the photographs the size of the premaxilla and the length of the incisal suture were measured. In addition, the spatial conditions in the anterior region were recorded. The study showed that the main closure of the suture takes place shortly after the crowns of the permanent incisors have attained their final width size. The mean size of the premaxillary area was larger in individuals with interincisal spacing and smaller in individuals with crowding when comparing with normal spatial conditions. In the cases of tooth agenesis the premaxillary areas were markedly reduced.

Impaction of maxillary canines and congenitally missing third molars. Description of an ancient skull (7250-6700 BC).

This report describes an ancient skull, in which both maxillary canines were impacted and mandibular third molars were missing. During the excavations at the early village site of Cayönü (Turkey), the subject of this report was found inside a skull building (charnel house) together with the fragments of 75 skulls, and was the least damaged skull of the Cayönü series (Ozbek, 1988). The skull showed skeletal and dental Class I relationship, with an orthognathic profile and a reduced bimaxillary alveolar prognathism. Assessment on the skull confirms the findings of the previous studies and reports that irregularities in the position of the teeth are already found in prehistoric man, and therefore, do not seem to be the result of modified conditions of modern civilization only.

[The absence of a central lower incisor in a medieval subject from the Norman cemetery of San Lorenzo di Aversa (Caserta)]. / Assenza dell'incisivo centrale inferiore in un soggetto medievale proveniente dal cimitero normanno di San Lorenzo di Aversa (Caserta).

The authors describes a case of hypodontia in a male subject aged about 45 years and coming from the medieval necropolis of San Lorenzo of Aversa (Caserta, South Italy), dated to 890-1290 A.D. Hypodontia consists of the absence of a central inferior incisor (probably the left). Radiographic examination excluded the presence of a healed traumatic lesion. For this reason, the authors suggests that the described hypodontia was related to a primary agenesia of the central inferior incisor.

[The congenital absence of the permanent upper lateral incisors with the persistence of the deciduous canines in a subject of the Iron Age from the Sulmona (AQ) necropolis]. / Assenza congenita degli incisivi laterali superiori permanenti con persistenza dei canini decidui in un soggetto dell'età del Ferro della necropoli di Sulmona (AQ).

The paper reports a case of bilateral agenesia of the permanent upper lateral incisors associated with the persistence of the deciduous eye teeth placed between the first premolars and the permanent canine teeth which, in turn, had emerged in place of the agenetic lateral incisors (situs dentis inversus) in a adult male from the Iron Age whose skeletal remains were exhumed from tomb no. 58 of the Sulmona necropolis (AQ). The authors place the case in the context of agenesia as found both in today's population and in ancient times.

Anomalous morphologic formation of deciduous and permanent teeth in a 5-year-old 15th century child: a variant of the Ekman-Westborg-Julin syndrome.

A gross morphologic anomaly affecting both the primary and secondary teeth of unknown cause is presented. A 5-year-old American Indian child exhibited macrodontia, extreme shovel-shaping, agenesis, three-rooted deciduous molars, dens invaginatus, and other less striking dental features. This case represents the earliest example of a variant of the Ekman-Westborg-Julin syndrome reported in the New World.