Dental disease is an indicator of oral health and diet for modern and past populations (DeWitte and Stojanowski 2015). Multiple conditions fall under this purview: dental caries, periodontal disease, abscesses, calculus, and antemortem tooth loss. Recent clinical literature emphasizes the relationship between dental pathology and general health, as oral infections can increase risk for multiple systemic complications such as spread of infection to other systems, cardiovascular disease, renal disease, cancers, and poor childhood growth (Glodny et al. 2013; Johnston and Veiera 2014; Williams et al. 2008; Ylostalo et al. 2006). The presence of periodontal disease and caries may also be an indicator of underlying disease causes such as compromised immunity (e.g. frailty) (DeWitte and Stojanowski 2015; Michaud et al. 2008). Dental disease is associated with age as dental attrition over long periods can erode enamel (Appleby 2010).
2.3.3.1 Etiology: Dental Diseases
Dental caries are areas of eroded dental enamel through which infection enters a tooth and their etiology and formation is multifactorial (Featherstone 2004; Fejerskov 2004). Oral bacteria are encapsulated in organic biofilm (plaque) that adheres to the teeth. Bacilli metabolize carbohydrates in the oral cavity, causing fermentation and the production of acids that in turn demineralize tooth enamel. Caries can expose the underlying dentin and pulp cavity
to oral bacteria, leading to further complications such as abscesses and periodontal disease (Featherstone 2004; Fejerskov 2004). Caries are recognizable on the dentition as discolored pits on the enamel and can occur on any tooth surface (Buikstra and Ubelaker 1994; Hillson 2005) (Figure 5). Starchy foods such as cereals and maize are known to be cariogenic, as they increase levels of fermentable carbohydrate in the oral cavity (Lieverse 1999).
Dental abscesses infections of the tooth pulp cavity with associated destruction of the alveolar bone at the base of the tooth root (Dias and Tayles 1997) (Figure 6). Pus forms and travels through the tooth root and out through the bone into the surrounding oral soft tissues, including the nasal cavities. Abscesses result in tooth loss and considerable pain and swelling (Dias and Tayles 1997). These lesions are recognizable osteologically as fistulas in the alveolar bone at the base of the tooth root (Lukacs 1989).
Dental calculus is mineralized dental plaque, predominantly composed of calcium phosphate. It occurs both on the tooth crown and tooth root, and is highly associated with poor oral hygiene (Waldron 2008). Calculus is observable on the dentition in the form of hardened-plaque like film, which can range from flat to extensive formation (Dobney and Brothwell 1987). Calculus formation is associated with high protein diets, rather than starchy foods (Lieverse 1999).
Periodontal disease is an infection of the alveolar bone surrounding the tooth socket (Kinane 2000; Page 2002). The surrounding gingival tissue becomes irritated and bleeds from the presence of cariogenic oral plaque, introducing bacteria into the tooth socket. The interaction between the host and bacteria produces an inflammatory process resulting in the formation soft tissue pockets between the tooth and gums. This ultimately results in the loosening of the tooth and subsequent tooth loss, with recession and remodeling of the alveolar bone (Kinane 2000; Page 2002). This condition is observable osteologically via receding alveolar bone, with associated pitting and remodeling. When severe, the alveolar bone may be completely receded to the base of the tooth root (Lukacs 1989) (Figure 5).
Antemortem tooth loss results from all of the above processes as well as trauma and intentional extraction for health or body modification purposes (Roberts and Manchester 2007; Waldron 2008). This condition is recognizable when the tooth socket is completely resorbed (Dobney and Brothwell 1987). Risk for this condition is associated with age and can result in poor nutrition if the individual becomes completely edentulous (Waldron 2008) (Figure 6).
Figure 5: Dental caries (left and periodontal disease (right), FC#5081, child, Middle Monongahela – Bunola site
Figure 6: Dental abscess (right) and AMTL (left), FC#5072, middle aged male, Middle Monongahela – Bunola site 2.3.3.2 Discussion: Gender and Dental Disease
Lukacs (2008, 2011a) argued that the transition to agriculture had lasting and detrimental consequences on gendered health patterns with specific reference to oral pathologies. The transition to agriculture has traditionally been associated with a significant decline in oral health due to the cariogenic properties of agricultural cereals (Cohen and Armelagos 1984; Eshed et al. 2006; Larsen 1995, 2002). Lukacs (2008, 2011a) documented a marked difference in caries rates between males and females following this event and offered an explanation for this pattern: female caries rates increase following the agricultural transition due to an increased demand in fertility and the concomitant effects of increased reproductive demands on other physiological systems as at the time of agricultural transition, population sizes increased while birth intervals decreased (Lukacs 2008, 2011a). He argued that female resistance to cariogenic bacteria decreases during pregnancy, relating the relative risk of caries among females to
hormonal influences. The type of agricultural grain varies from region to region and these patterns are observable in multiple populations from varied environments. This demonstrates that hormonal levels are one of the primary risk factors in female oral pathology as female caries rates are high in multiple regions. Lukacs (2008, 2011a) offered a model based upon the complex etiology of caries, emphasizing that hormonal influences, dietary changes, and gendered behavior contributed to patterns of oral pathology in the past.
Modern anthropological studies utilizing clinical data can shed light on the effect of gendered cultural practice and health. Lukacs (2011b) used metadata to assess the interaction between dental disease, sex, and gendered cultural behavior in South Asia via evaluations of reported rates of periodontal disease, tooth loss, and filling treatments for caries in modern clinical samples from India, Nepal, Bangladesh and Sri Lanka. He demonstrated that male caries rates were higher than those of females during childhood, but the gender bias reversed at reproductive maturity through old age. Some samples diverged from this predominant pattern with rare male gender bias in adults and others samples showed no significant difference by sex (Lukacs 2011b). Lukacs (2011b) suggested this pattern of female bias was due to several biological factors: genetic factors and hormonal influence from childbearing. Aside from these biological influences, Lukacs (2011b) found that gendered social norms played a significant role in the differences between the sexes in expression of dental disease. A cultural preference for a son may have considerable effect on female oral health as boys are given preferential food access, with the result being that chronic undernourishment of females in early childhood decreases resistance to caries (Lukacs 2011b). Pearson (1996) described practices of religious fasting among Hindu women, who frequently fast for short-term (2- 3 days) and long-term (week to 10 days) periods, while males rarely or never participate in these activities. Women in South Asia also engage in restricted diets during pregnancy due to cultural beliefs about low birth weight and easy childbirth (Vallianatos 2006). Undernourishment and dietary restriction can alter saliva flow and biochemical composition that promote cariogenesis, so these cultural practices could have a marked impact on female oral health (Lukacs 2011b). Gendered dietary practices such fasting or preferential food access could have also affected oral health in prehistoric populations, and should be considered in bioarchaeological interpretations of dental disease.