Amelogenesis imperfecta in the dentition of a wild chimpanzee

Towle, Ian; Irish, Joel D.; Groote, Isabelle De

doi:10.1111/jmp.12323

Cited by 5 publications

(2 citation statements)

References 24 publications

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“…Defects are often characterized into one of four categories: linear-form (LEH), pit-form (PEH), plane-form (PFEH), and localized enamel hypoplasia [1,[4][5][6][7]. Te classifcation of defects into these categories can sometimes be difcult, e.g., [7][8][9][10]. Enamel hypoplasia has been commonly recorded and described in archaeological and paleontological studies, with the "health" or "stress" status of populations or taxa often assessed using hypoplasia as a proxy, e.g., [2,[11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…In humans, severe tooth defects in which large areas of enamel do not form correctly often relate to diseases and environmental factors such as localized trauma, congenital syphilis, medical treatments associated with the use of mercury, and specifc genetic conditions such as amelogenesis imperfecta [8,9,[17][18][19]. Such severe dental defects, like PFEH, are rarely observed in wild primates [10].…”

Section: Introductionmentioning

confidence: 99%

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Severe Enamel Defects in Wild Japanese Macaques

Towle,

Loch,

Martínez de Pinillos

et al. 2024

International Journal of Zoology

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Plane-form enamel hypoplasia (PFEH) is a severe dental defect in which large areas of the crown are devoid of enamel. This condition is rare in humans and even rarer in wild primates. The etiology of PFEH has been linked to exposure to severe disease, malnutrition, and environmental toxins and associated with systemic conditions. In this study, we examined the prevalence of enamel hypoplasia in several populations of wild Japanese macaques (Macaca fuscata) with the aim of providing context for severe defects observed in macaques from Yakushima Island. We found that 10 of 21 individuals (48%) from Yakushima Island displayed uniform and significant PFEH; all 10 specimens were from two adjacent locations in the south of the island. In contrast, macaques from other islands and from mainland Japan have a low prevalence of the more common types of enamel hypoplasia and none exhibit PFEH. In Yakushima macaques, every tooth type was affected to varying degrees except for first molars and primary teeth, and the mineral content of the remaining enamel in teeth with PFEH was normal (i.e., no hypo- or hypermineralization). The aetiology of PFEH might be linked to extreme weather events or high rates of environmental fluoride-causing enamel breakdown. However, given that the affected individuals underwent dental development during a period of substantial human-related habitat change, an anthropogenic-related etiology seems most likely. Further research on living primate populations is needed to better understand the causes of PFEH in wild primates.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Severe Enamel Defects in Wild Japanese Macaques

Towle,

Loch,

Martínez de Pinillos

et al. 2024

International Journal of Zoology

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Recording and interpreting enamel hypoplasia in samples from archaeological and palaeoanthropological contexts

Towle

Irish

2020

Journal of Archaeological Science

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Enamel hypoplasia is often split into several macroscopic categories, including pit, localised, linear and plane-form defects. All types have been considered a sign of 'non-specific stress' during dental development in archaeological, as well as palaeoanthropological and other samples. There is growing evidence suggesting many defects may not be caused by illness or malnutrition during childhood, instead relating to trauma to the developing tooth, genetic conditions or specific environmental factors, i.e., may not be associated with 'stress' to the individual. In this study all types of macroscopic enamel hypoplasia were recorded, including pitting, linear, plane and localised type defects, in three extant primate species and three fossil hominin species. The aim is to compare the characteristics and prevalence of different types of enamel hypoplasia among species and discuss potential differences in aetiology. The results show that samples have diverse prevalences of different kinds of defects, and pitting, linear and localised defects likely have different aetiologies. Additionally, dental characteristics (e.g., tooth morphology, developmental timing/speed and enamel structure) heavily influence the likelihood of specific types of enamel hypoplasia forming. In sum, studies that include only one type of enamel hypoplasia, or focus on one tooth type, to generate a 'stress' rating for a sample may miss relevant information when comparing groups. Instead, it may be beneficial to record different types of defects separately, for all teeth, and then consider how genetic, environmental and tooth property factors may influence population differences.

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A probable genetic origin for pitting enamel hypoplasia on the molars of Paranthropus robustus

Towle

2019

Journal of Human Evolution

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We report the frequencies of linear enamel hypoplasia (LEH) and, specifically, pitting enamel hypoplasia (PEH) defects in the teeth of Paranthropus robustus, for comparison with four other South African hominin species and three extant nonhuman primate species. Unlike LEH, the lesser known PEH is characterized by multiple circular depression defects across a tooth crown and is often difficult to interpret in terms of developmental timing and etiology. Teeth in all samples were examined macroscopically with type, position and number of defects recorded. Frequencies of teeth with LEH vary among hominin species, but the differences in PEH are considerable. That is, P. robustus has much higher rates of pitting defects, with 47% of deciduous teeth and 14% of permanent teeth affected, relative to 6.7% and 4.3%, respectively, for all other hominin teeth combined; none of the extant primate samples evidence comparable rates. The defects on P. robustus molars are unlike those in other species, with entire crowns often covered in small circular depressions. The PEH is most consistent with modern human examples of amelogenesis imperfecta. Additionally, the defects are: 1) not found on anterior teeth, 2) uniform in shape and size, and 3) similar in appearance/severity on all molars. A possible reason for this form of PEH is as a side effect of selection on another phenotype that shares the same coding gene(s), i.e., a genetic origin. Recent research on the ENAM gene provides one such possibility. Paranthropus likely underwent rapid evolution in the ENAM loci, with changes in this gene contributing to larger posterior teeth and thicker enamel. This same gene is associated with amelogenesis imperfecta; therefore, pleiotropy effects, relating to high selection on this gene during Paranthropus evolution, could have yielded this unique condition.

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Amelogenesis imperfecta in the dentition of a wild chimpanzee

Cited by 5 publications

References 24 publications

Severe Enamel Defects in Wild Japanese Macaques

Severe Enamel Defects in Wild Japanese Macaques

Recording and interpreting enamel hypoplasia in samples from archaeological and palaeoanthropological contexts

A probable genetic origin for pitting enamel hypoplasia on the molars of Paranthropus robustus

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