Cultural diversity of traditions for the disposal of exfoliated teeth: Implications for researchers.

OBJECTIVES: For decades, researchers in anthropology and archaeology have used teeth, including exfoliated primary teeth, as fossil records of people's physical life experiences. Recently, researchers in psychiatry, epidemiology, environmental health and other fields have recognized the potential for teeth to serve as biomarkers of other early-life experiences, including trauma exposure and other types of psychosocial stress, which are potent determinants of later mental and physical health problems. Despite the emerging appreciation and value of teeth as biospecimens, little is understood about cultural beliefs and practices surrounding exfoliated teeth. If known, such insights could inform culturally appropriate practices for paediatric dental care and improve protocols for the ethical acquisition of teeth as biospecimens in research studies. To address this gap, a qualitative systematic review was performed to summarize the variety of traditions performed worldwide for disposing of primary exfoliated teeth. METHODS: PubMed, Google Scholar, AnthroSource, Anthropological Literature, EHRAF World Cultures and Anthropology Plus were searched with a systematic search strategy to identify articles published from inception through December 2, 2021. Citations of relevant papers were also forward and backward searched. RESULTS: There were 3289 articles that met the initial inclusion criteria, of which 37 were included after individual screening and applying exclusion criteria. Thematic analysis was used to identify 74 distinct traditions related to the disposal of exfoliated teeth, which were organized into seven general themes: (1) giving teeth to a tooth fairy, (2) giving teeth to mouse figures, (3) throwing teeth, (4) hiding/keeping teeth, (5) burying teeth, (6) giving teeth to animals and (7) eating the tooth. CONCLUSIONS: The results of this study elucidate the diversity within-yet universality of-exfoliated tooth disposal traditions and underscore the importance of tooth exfoliation as a major milestone during child development. Special attention must be paid to these traditions and related ethical concerns when designing research protocols related to their collection. With a greater understanding of beliefs and practices related to exfoliated teeth, researchers will be better equipped to engage children and families in studies that include analyses of exfoliated teeth, collect teeth as biospecimens, and broaden the use of teeth in research.

Thermoneutral housing does not rescue olanzapine-induced trabecular bone loss in C57BL/6J female mice.

Antipsychotic drugs are prescribed to a wide range of individuals to treat mental health conditions including schizophrenia. However, antipsychotic drugs cause bone loss and increase fracture risk. We previously found that the atypical antipsychotic (AA) drug risperidone causes bone loss through multiple pharmacological mechanisms, including activation of the sympathetic nervous system in mice treated with clinically relevant doses. However, bone loss was dependent upon housing temperature, which modulates sympathetic activity. Another AA drug, olanzapine, has substantial metabolic side effects, including weight gain and insulin resistance, but it is unknown whether bone and metabolic outcomes of olanzapine are also dependent upon housing temperature in mice. We therefore treated eight week-old female mice with vehicle or olanzapine for four weeks, housed at either room temperature (23 °C) or thermoneutrality (28-30 °C), which has previously been shown to be positive for bone. Olanzapine caused significant trabecular bone loss (-13% BV/TV), likely through increased RANKL-dependent osteoclast resorption, which was not suppressed by thermoneutral housing. Additionally, olanzapine inhibited cortical bone expansion at thermoneutrality, but did not alter cortical bone expansion at room temperature. Olanzapine also increased markers of thermogenesis within brown and inguinal adipose depots independent of housing temperature. Overall, olanzapine causes trabecular bone loss and inhibits the positive effect of thermoneutral housing on bone. Understanding how housing temperature modulates the impact of AA drugs on bone is important for future pre-clinical studies, as well as for the prescription of AA drugs, particularly to older adults and adolescents who are most vulnerable to the effects on bone.

Social isolation through single housing negatively affects trabecular and cortical bone in adult male, but not female, C57BL/6J mice.

Social isolation is a potent form of psychosocial stress and is a growing public health concern, particularly among older adults. Even prior to the onset of the COVID-19 pandemic, which has significantly increased the prevalence of isolation and loneliness, researchers have been concerned about a rising "epidemic" of loneliness. Isolation is associated with an increased risk for many physical and mental health disorders and increased overall mortality risk. In addition to social isolation, older adults are also at greater risk for osteoporosis and related fractures. While researchers have investigated the negative effects of other forms of psychosocial stress on bone, including depression and PTSD, the effects of social isolation on bone have not been thoroughly investigated. The aim of this study was to test the hypothesis that social isolation would lead to bone loss in male and female C57BL/6J mice. 16-week-old mice were randomized into social isolation (1 mouse/cage) or grouped housing (4 mice/cage) for four weeks. Social isolation significantly decreased trabecular (BV/TV, BMD, Tb. N., Tb. Th.) and cortical bone (Ct.Th., Ct.Ar., Ct.Ar./Tt.Ar., pMOI) parameters in male, but not female mice. Isolated male mice had signs of reduced bone remodeling represented by reduced osteoblast numbers, osteoblast-related gene expression and osteoclast-related gene expression. However, isolated females had increased bone resorption-related gene expression, without any change in bone mass. Overall, our data suggest that social isolation has negative effects on bone in male, but not female mice, although females showed suggestive effects on bone resorption. These results provide critical insight into the effects of isolation on bone and have key clinical implications as we grapple with the long-term health impacts of the rise in social isolation related to the COVID-19 pandemic.

Social Isolation Causes Cortical and Trabecular Bone Loss in Adult Male, but not Female, C57BL/6J Mice.

Social isolation is a potent form of psychosocial stress and is a growing public health concern, particularly among older adults. Even prior to the onset of the COVID-19 pandemic, which has significantly increased the prevalence of isolation and loneliness, researchers have been concerned about a rising "epidemic" of loneliness. Isolation is associated with an increased risk for many physical and mental health disorders and increased overall mortality risk. In addition to social isolation, older adults are also at greater risk for osteoporosis and related fractures. While researchers have investigated the negative effects of other forms of psychosocial stress on bone, including depression and PTSD, the effects of social isolation on bone have not been thoroughly investigated. The aim of this study was to test the hypothesis that social isolation would lead to bone loss in male and female C57BL/6J mice. 16-week-old mice were randomized into social isolation (1 mouse/cage) or grouped housing (4 mice/cage) for four weeks (N=16/group). Social isolation significantly decreased trabecular (BV/TV, BMD, Tb. N., Tb. Th.) and cortical bone (Ct.Th., Ct.Ar., Ct.Ar./Tt.Ar., pMOI, Ct.Por.) parameters in male, but not female mice. Isolated male mice had signs of reduced bone remodeling represented by reduced osteoblast numbers, osteoblast-related gene expression and osteoclast-related gene expression. However, isolated females had increased bone resorption-related gene expression, without any change in bone mass. Overall, our data suggest that social isolation has negative effects on bone in males, but not females, although females showed suggestive effects on bone resorption. These results provide critical insight into the effects of isolation on bone and have key clinical implications as we grapple with the long-term health impacts of the rise in social isolation related to the COVID-19 pandemic.

Association of Maternal Stress and Social Support During Pregnancy With Growth Marks in Children's Primary Tooth Enamel.

Importance: Exposure to maternal psychosocial stressors during the prenatal and perinatal periods can have major long-term mental health consequences for children. However, valid and inexpensive biomarkers are currently unavailable to identify children who have been exposed to psychosocial stress and the buffers of stress exposure. Objective: To assess whether a growth mark in tooth enamel, the neonatal line, is associated with exposure to prenatal and perinatal maternal psychosocial factors. Design, Setting, and Participants: This prospective cohort study used exfoliated primary canine teeth and epidemiological survey data from 70 children enrolled in the Avon Longitudinal Study of Parents and Children, a birth cohort based in Bristol, England. Exfoliated teeth were collected from children at 5 to 7 years of age. Data were collected from January 1, 1991, to December 31, 1998, and were analyzed from January 1, 2019, to August 10, 2021. Exposures: Four types of prenatal and perinatal maternal psychosocial factors were studied: stressful life events, psychopathological history, neighborhood disadvantage, and social support. Data were collected from mailed-in questionnaires completed during and shortly after pregnancy. Main Outcomes and Measures: Neonatal line width measured within 3 portions of the tooth crown (the cuspal, middle, and innermost third) in exfoliated primary canines. Results: A total of 70 children (34 of 70 [48.7%] male; 63 of 67 [94.0%] White) were studied. Most children were born full term (57 [83.8%]) and to mothers of typical child-bearing age (60 [88.2%]). Neonatal lines were wider in the canines of children born to mothers who self-reported severe lifetime depression (ß = 3.35; 95% CI, 1.48-5.23; P = .001), any lifetime psychiatric problems (ß = 2.66; 95% CI, 0.92-4.41; P = .003), or elevated anxiety or depressive symptoms at 32 weeks' gestation (ß = 2.29; 95% CI, 0.38-4.20; P = .02). By contrast, neonatal lines were narrower in children born to mothers who self-reported high social support shortly after birth (ß = -2.04; 95% CI, -3.70 to -0.38; P = .02). The magnitude of these associations was large, up to 1.2 SD unit differences, and persisted after adjusting for other risk factors. Conclusions and Relevance: In this cohort study, neonatal line width was associated with exposure to maternal perinatal psychosocial factors. Replication and validation of these findings can further evaluate teeth as possible new biomarkers.

Teeth as Potential New Tools to Measure Early-Life Adversity and Subsequent Mental Health Risk: An Interdisciplinary Review and Conceptual Model.

Early-life adversity affects nearly half of all youths in the United States and is a known risk factor for psychiatric disorders across the life course. One strategy to prevent mental illness may be to target interventions toward children who are exposed to adversity, particularly during sensitive periods when these adversities may have even more enduring effects. However, a major obstacle impeding progress in this area is the lack of tools to reliably and validly measure the existence and timing of early-life adversity. In this review, we summarize empirical work across dentistry, anthropology, and archaeology on human tooth development and discuss how teeth preserve a time-resolved record of our life experiences. Specifically, we articulate how teeth have been examined in these fields as biological fossils in which the history of an individual's early-life experiences is permanently imprinted; this area of research is related to, but distinct from, studies of oral health. We then integrate these insights with knowledge about the role of psychosocial adversity in shaping psychopathology risk to present a working conceptual model, which proposes that teeth may be an understudied yet suggestive new tool to identify individuals at risk for mental health problems following early-life psychosocial stress exposure. We end by presenting a research agenda and discussion of future directions for rigorously testing this possibility and with a call to action for interdisciplinary research to meet the urgent need for new biomarkers of adversity and psychiatric outcomes.