An anthropological perspective: another dimension to modern dental wear concepts

Early evidence of extra-masticatory dental wear in a Neolithic community at Bestansur, Iraqi Kurdistan

This paper presents the first evidence of extra-masticatory dental wear from Neolithic Bestansur, Iraqi Kurdistan (7700-7200 BC). Bestansur is a rare, recently excavated burial site of this period in the Zagros region, of Iraqi Kurdistan. A total of 585 teeth from 38 individuals were analyzed for features indicative of activities including oblique wear planes, notches, grooves, and chipping. Indications of extra-masticatory wear were found in 27 of 38 individuals, and 277 of 585 teeth (47%) available for study. The most frequent features were chipping and notches suggesting activities such as processing fibers by using the teeth as a "third hand." Evidence for these wear features was present in both males, females, and in children aged five and older. These aspects of childhood life-course and dentition are rarely investigated. The presence of dental wear features in the deciduous dentition can indicate an age range at which activities began in different groups and highlights the importance of including juvenile remains in such studies. The variety of forms of dental wear may relate to the mixed diet and activities of these people. This study adds to our understanding of human behaviors and socio-cultural aspects of life during this transitional period.

Dimorphism in dental tissues: Sex differences in archaeological individuals for multiple tooth types

OBJECTIVES

Dimorphism in the dentition has been observed in human populations worldwide. However, research has largely focused on traditional linear crown measurements. As imaging systems, such as micro-computed tomography (micro-CT), become increasingly more accessible, new dental measurements such as dental tissue size and proportions can be obtained. This research investigates the variation of dental tissues and proportions by sex in archaeological samples.

MATERIALS AND METHODS

Upper and lower first incisor to second premolar tooth rows were obtained from 30 individuals (n = 300), from 3 archaeological samples. The teeth were micro-CT scanned and surface area and volumetric measurements were obtained from the surface meshes extracted. Dental wear was also recorded and differences between sexes determined.

RESULTS

Enamel and crown measurements were found to be larger in females. Conversely, dentine and root measurements were larger in males.

DISCUSSION

The findings support the potential use of dental tissues to estimate sex of individuals from archaeological samples, while also indicating that individuals aged using current dental aging methods may be underaged or overaged due to sex differences in enamel thickness.

Dental health status of skeletal remains excavated from an abandoned well at Ajnala, India: a bioarchaeological study

Present study was conducted to assess dental health status of the mid-19th century skeletal remains excavated from an abandoned ancient well and to scrutinize the demographic affiliations of the remains. Thousands of bones, teeth and contextual items were excavated non-scientifically from an abandoned well situated underneath a religious structure at Ajnala (Amritsar, India). Four thousands four hundred and seventy five teeth of each type were examined for presence of dental pathologies of caries, wear and linear enamel hypoplasia (LEH). The frequency distribution of each pathological state was calculated for each tooth type using international dental standards available in the literature. The overall dental status was characteristic of young individuals having low prevalence of dental caries and enamel hypoplasiac lesions. Very few teeth had seriously exposed dentine and pulp cavity; indicating consumption of some cariogenic food items. The maxillary and posterior teeth were more affected with dental caries than the mandibular and anterior teeth. LEH defects were found more commonly distributed in the lower canines (44.9%) and upper incisors (34.8%) than their corresponding counterparts and statistically significant differences were noticed in LEH prevalence between anterior and, posterior dentition. The overall percentage of LEH has been found as 15.8%; with 15.4% maxillary and 16.2% mandibular teeth being affected with LEH. The paleodontogical examinations, contextual items and the preliminary molecular findings supported the written versions that victims of Ajnala skeletal remains had sound dental health status and probably belonged to adult males who were killed in 1857 as per written versions.

Root grooves on two adjacent anterior teeth of Australopithecus africanus

Tooth root grooves and other ante-mortem dental tissue loss, not associated with caries found on or near the cementoenamel junction (CEJ), are commonly termed non-carious cervical lesions. Three main processes are implicated in forming these lesions: abrasion, dental erosion, and abfraction. As yet, these lesions have not been described in non-Homo hominins. In this study, South African fossil hominin collections were examined for evidence of any type of non-carious cervical lesion. Only one individual shows ante-mortem root grooves consistent with non-carious cervical lesions. Two teeth, a mandibular right permanent lateral incisor (STW 270) and canine (STW 213), belonging to the same Australopithecus africanus individual, show clear ante-mortem grooves on the labial root surface. These lesions start below the CEJ, extend over a third of the way toward the apex, and taper to a point towards the lingual side. The characteristics of these grooves suggest the predominant aetiology was erosive wear. In addition, they are extremely similar to clinical examples of dental erosion. These are the oldest hominin examples of non-carious cervical lesions and the first described in a genus other than Homo. Further, the lesions suggest that this individual regularly processed and consumed acidic food items.

The 'sialo-microbial-dental complex' in oral health and disease

Biofilms are naturally found in all wet environments including the oral structures of nearly all species. Human oral biofilms have existed since our earliest ancestors and have evolved symbiotically with the dentition over many millennia within a Palaeolithic, hunter-gatherer setting. Irrespective of the plant-animal ratio, it can be argued that the Palaeolithic diet was essentially acidic, and acted as a selective force for much of the evolution of the stomatognathic system. The relationship between saliva, biofilm and teeth, the 'sialo-microbial-dental complex', provides oral health benefits and offers a different perspective to the old dental paradigm that only associated oral biofilms (plaque) with disease (caries). This new paradigm emphasises that oral biofilms are essential for the 'mineral maintenance' of teeth. Oral biofilms provide physical protection from dietary acid and together with bacterial metabolic acids cause the resting pH of the biofilm to fall below neutral. This is then followed by the re-establishment of a neutral environment by chemical interactions mediated by the saliva within the biofilm. Such pH fluctuations are often responsible for the cyclic demineralisation, then remineralisation of teeth, a process necessary for tooth maturation. However, since the advent of farming and especially since the industrial revolution, the increase in consumption of carbohydrates, refined sugars and acidic drinks has changed the ecology of biofilms. Biofilm biodiversity is significantly reduced together with a proliferation of acidogenic and aciduric organisms, tipping the balance of the 'demin-remin' cycle towards net mineral loss and hence caries. In addition, the consumption of acidic drinks in today's societies has removed the protective nature of the biofilm, leading to erosion. Erosion and caries are 'modern-day' diseases and reflect an imbalance within the oral biofilm resulting in the demineralisation of teeth.

Functional dental occlusion: an anthropological perspective and implications for practice

Physiologic changes occur in dental occlusion throughout life, resulting from the interplay between functional demands and reciprocating adaptive responses. These changes have been reported in the anthropological literature and they reflect evolutionary changes in the human stomatognathic system during the Paleolithic, hunter-gatherer period. Specific occlusal changes occur in response to different environments, leading to extensive variation within and between extinct and extant human populations. For example, functional demands can cause occlusal and interproximal tooth wear, resulting in shortening of the dental arch, continual tooth eruption and changes in masticatory patterns. Since the advent of farming through to our current industrialized culture, functional demands on the human masticatory system, and its adaptive responses to these demands, have been reduced considerably. Indeed, it is only occasionally that functional demands are severe enough to lead to obvious pathology in the modern human dentition. In contrast to normal masticatory activity, 'modern-day conditions' such as dental caries, periodontal disease and erosion, can lead to significant changes in dental occlusion that are pathological and need to be treated. The masticatory system is a dynamic, functional unit that displays considerable change over a lifetime. In this concept paper, it is proposed that modern human populations living in industrialized environments display dental occlusions that can be considered to be 'neotenous'; that is, our dentitions tend to reflect an unworn stage of our ancestors that was only seen in infants, juveniles and young adults. Clinicians can draw on both phylogenetic and ontogenetic perspectives of 'functional dental occlusion' to differentiate continual physiological changes occurring over time that require ongoing review, from pathological responses that require intervention.