The higher prevalence of developmental defects of enamel in the dioxin-affected region than non-dioxin-affected region: result from a cross-sectional study in Vietnam

Effects of Polychlorinated Dibenzo-p-dioxins, Polychlorinated Dibenzofurans, and Dioxin-like PCBs on Teeth and Bones in Animals and Humans

Bone metabolism is regulated by endocrine systems, so people exposed to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) may suffer adverse effects on bones and teeth. We reviewed previous publications in which effects of PCDD/Fs and dioxin-like polychlorinated biphenyls on the teeth and bones of animals and humans were found. The aim was to identify future research directions, particularly for epidemiological studies of populations exposed to PCDD/Fs in the environment. Exposure of fetuses to PCDD/Fs may affect odontogenesis, particularly enamel formation, but the effects of PCDD/Fs on bone genesis are limited to palatine bone. Exposure to PCDD/Fs in milk may affect both teeth and bones, but the effects on bones may be reversible. Exposure to high PCDD/F concentrations even during adulthood may adversely affect teeth. Exposure to PCDD/Fs may induce osteogenesis and improve bone properties because the disrupting effects of PCDD/Fs cause bone remodeling and vitamin D activation. More studies involving humans are required to investigate previously found associations between the PCDD/F concentrations humans are exposed to and biological markers for teeth and bones, including metabolites of vitamin D.

Validity of partial protocols to evaluate the prevalence of developmental defects of enamel in permanent dentition: a birth cohort study in Southern Brazil

OBJECTIVES

To evaluate the validity of partial protocols (PP) to assess the prevalence of developmental defects of enamel (DDE) in permanent teeth and identify the strength of the association between DDE and some risk factors, using PP compared to the full-mouth (FM) exam.

MATERIALS AND METHODS

This study was conducted in a population-based birth cohort of children born in 2004 in Pelotas, Southern Brazil. Socioeconomic, demographic, pre-, per-, and post-birth variables were collected. A subsample of 994 children was clinically examined for DDE in 2017, using the modified DDE index, using the "full- mouth" (FM) protocol. After FM had been performed, a dataset was created. Two different partial protocols (PP) were simulated from FM data: "only buccal surfaces (BS)" and "incisive and molars only (IM)." Sensitivity, absolute and relative bias, and inflation factors were calculated.

RESULTS

For any DDE, FM had prevalence of 40.8%. The prevalence of DDE was 38.8% and 36.0%, for BS and IM protocols, respectively. When tested for any DDE, PP "BS" and "IM" showed high sensitivity. The underestimation of the true prevalence did not exceed 6.9% for PP "BS" and 16.1% for PP "IM." All protocols showed similar magnitude of association with the selected risk factors.

CONCLUSION

Both PP "BS" and "IM" can be used to estimate the prevalence of DDE in epidemiological studies.

CLINICAL RELEVANCE

Oral health surveys now have the option of using PP to collect DDE prevalence and investigate their association with risk factors, being less time-consuming, expensive, and labor intensive.

Factors and Mechanisms Involved in Acquired Developmental Defects of Enamel: A Scoping Review

BACKGROUND

Developmental Defects of Enamel (DDE) is a pathology of the teeth that can greatly alter the quality of life of patients (hypersensitivity, esthetic issues, loss of function, etc.). The acquired DDE may occur as a result of a wide range of acquired etiological factors and his prevalence of this pathology may reach up to 89.9%. The main objective of this research was to identify and analyze, in current literature, the factors related to acquired DDE, in order to propose a general theory about the mechanisms involved.

METHODS

The search of the primary literature was conducted until [December 31, 2021]. Our search strategy uses the Pubmed/MEDLINE database and was structured around 3 terms ["Development," "Defect," and "Enamel"]. To be included, references had to be primary studies, written in English. Exclusion criteria were reviews, in vitro, animal, genetic or archeology studies, and studies focused on clinical management of DDE. One hundred and twenty three articles were included in this scoping review: 4 Randomized clinical trials, 1 letter, 5 cases reports, 2 fundamentals studies, and 111 observational studies (33 Cross-sectional studies, 68 Cohort study and 10 Case-control study). The quality of evidence was assessed using the PEDro scale for clinical trials, the Newcastle-Ottawa scale for observational studies, and a published tool to assess the quality of case reports and case series.

RESULTS

A scoping review of the literature identified 114 factors potentially involved in acquired DDE. The most frequently encountered pathologies are those causing a disorder of calcium homeostasis or a perturbation of the ARNT pathway in mother or child. The link between the ARNT pathway and metabolism deficiency in uncertain and needs to be defined. Also, the implication of this mechanism in tissue impairment is still unclear and needs to be explored.

CONCLUSIONS

By identifying and grouping the risk factors cited in the literature, this taxonomy and the hypotheses related to the mechanism allow health practitioners to adopt behaviors that limit the risk of developing aDDE and to set up a prevention of dental pathology. In addition, by reviewing the current literature, this work provides guidance for basic research, clinical studies, and literature searches.

Relation between molar-incisor hypomineralization (MIH) occurrence and war pollutants in bombarded regions: Epidemiological pilot study in Lebanon

Background

Molar-incisor hypomineralization (MIH), a developmental enamel defect affecting one or more first permanent molars (FPMs) and sometimes incisors (PIs), is one of the most common pandemic health problems in the world. MIH etiology is still unclear and has been suggested to be related to exposure to environmental toxicants during enamel mineralization.

Aims

To assess the susceptibility to MIH occurrence in regards to war pollutants through the investigation of the prevalence and the clinical characteristics of MIH in a group of Lebanese children whose FPMs and PIs enamel mineralization coincides with the 2006 Lebanese war.

Patients and Methods

This cross-sectional study was performed in schools from different regions of Lebanon. Schoolchildren born in 2004, 2005, 2006, and 2007 were examined for MIH. Clinical status, lesion type, extension, and severity were recorded using the short form chart of the MIH index. Pearson's Chi-square or Fischer's exact test were used to determine if there is a significant relationship between categorical variables.

Results

An overall MIH prevalence of 22.93% has been reported. Forty-seven point seventy-five per cent had both molars and incisors affected. Demarcated opacities were the most frequently observed clinical status. Most of the MIH FPMs and PIs were mildly affected with lesions extended on less than the third of the tooth surface.

Conclusions

MIH prevalence among children born around 2006 Lebanese war is high. The hypothesis of a relation between MIH susceptibility and war pollutants in bombarded regions is legible but requires to be elucidated via additional in vitro and in vivo studies for accurate risk assessment.

Exposure to persistent organic pollutants during tooth formation: molecular mechanisms and clinical findings

Persistent organic pollutants (POPs) constitute a relevant part of environmental pollution. POPs are chemical compounds that persist for a long time in the environment, bio-accumulate in the human body and determine significant adverse consequences to human health. The characteristics of these substances are lipo-affinity, semi-volatility and resistance to the degradation processes. Results deriving from several different studies attest that exposure to the main classes of POPs results in multiple toxic effects on humans and experimental animal models. Among the various alterations caused by exposition to and bio-accumulation of POPs, there are abnormalities in tooth formation and related hard dental tissue structure, especially enamel. This review aimed to describe the close association between the exposure of these compounds during the development of the tooth germ and the occurrence of tooth structural anomalies. Indeed, structural defects of the enamel have as possible consequences higher susceptibility of the tooth to caries disease and higher fragility of the crown to the occlusal trauma.

Molar-incisor hypomineralisation in Lebanon: association with prenatal, natal and postnatal factors

BACKGROUND

Molar-incisor hypomineralisation is an enamel developmental defect highly prevalent in Lebanon. Literature suggests that perinatal conditions and childhood illnesses might be potential aetiological factors for this affection.

AIMS

This case-control study aimed to investigate the association of MIH with prenatal, natal and postnatal factors amongst 7-9 years Lebanese children and to end up with recommendations to overcome its occurrence.

METHODS

Self-administered, structured questionnaire including potential etiological factors was distributed to 659 MIH and non-MIH children's parents. The analysis of data was carried out using Statistical Package for Social Sciences Computer Software (SPSS 21.0, Inc., Chicago, IL, USA). For Statistical analysis, Pearson's chi-square, Fischer's exact test and multivariate regression model were used. A p value of less than 0.05 was considered statistically significant.

RESULTS

Children whose mothers had consumed food and drinks canned during pregnancy had 2.9 (CI: 1.367 to 6.187) times more likely to have MIH. Those who had history of taking antibiotics had 2.15 (CI: 1.186 to 3.909) times higher odds of MIH than those who did not have while those who had fever episodes during the early childhood years were 2.057 (CI: 1.149 to 3.683) times more likely to develop MIH.

CONCLUSION

During early childhood, careful handling of high fever, greater public awareness regarding misuse of antibiotics and education about bisphenol A and how to avoid it during pregnancy and breastfeeding are recommended to decrease the occurrence of MIH.

Severe dioxin-like compound (DLC) contamination in e-waste recycling areas: An under-recognized threat to local health

Electrical and electronic waste (e-waste) burning and recycling activities have become one of the main emission sources of dioxin-like compounds (DLCs). Workers involved in e-waste recycling operations and residents living near e-waste recycling sites (EWRS) are exposed to high levels of DLCs. Epidemiological and experimental in vivo studies have reported a range of interconnected responses in multiple systems with DLC exposure. However, due to the compositional complexity of DLCs and difficulties in assessing mixture effects of the complex mixture of e-waste-related contaminants, there are few studies concerning human health outcomes related to DLC exposure at informal EWRS. In this paper, we have reviewed the environmental levels and body burdens of DLCs at EWRS and compared them with the levels reported to be associated with observable adverse effects to assess the health risks of DLC exposure at EWRS. In general, DLC concentrations at EWRS of many countries have been decreasing in recent years due to stricter regulations on e-waste recycling activities, but the contamination status is still severe. Comparison with available data from industrial sites and well-known highly DLC contaminated areas shows that high levels of DLCs derived from crude e-waste recycling processes lead to elevated body burdens. The DLC levels in human blood and breast milk at EWRS are higher than those reported in some epidemiological studies that are related to various health impacts. The estimated total daily intakes of DLCs for people in EWRS far exceed the WHO recommended total daily intake limit. It can be inferred that people living in EWRS with high DLC contamination have higher health risks. Therefore, more well-designed epidemiological studies are urgently needed to focus on the health effects of DLC pollution in EWRS. Continuous monitoring of the temporal trends of DLC levels in EWRS after actions is of highest importance.

The dental arch dimensions in Vietnamese children at 7 years of age, and their variation by gender and ethnicity

Purpose

Dental arch dimensions are important not only in dentistry (e.g. orthodontists and prosthodontists, and forensic odontology), but also other medical fields, biology, biometrics, painting or sculpture. This study aimed to determine these dimensions in Vietnamese children and compare these measurements across four ethnic groups and genders.

Methods

A cross-sectional study was conducted on 3204 Vietnamese children at 7 years of age from four major ethnic groups in Vietnam (Kinh, Tay, Thai and Muong).

Results

The means variables in study subjects were 33.72 ± 2.16 mm for upper inter-canine width (UCW); 52.74 ± 2.55 mm for upper inter-molar width (UMW); 8.69 ± 1.79 mm for upper anterior length (UAL); 29.59 ± 1.97 mm for upper posterior length (UPL); 26.94 ± 2.49 mm for lower inter-canine width (LCW); 45.89 ± 2.59 mm for lower inter-molar width (LMW); 5.04 ± 1.53 mm for lower anterior length (LAL); and 26.22 ± 2.07 mm for lower posterior length (LPL). The UCM, UMW, and LMW of Muong were significantly wider in males, but narrower in females compared with other ethnic groups. The Kinh, Tay and Thai groups had no significant differences between genders in all dimensions, but these sizes were significantly larger in males than females of Muong group.

Conclusions

This study presents the means of dental arch dimensions in 7 year-old Vietnamese children, and there is no statistical differences in these dimensions between genders of almost studied groups, except Muong group. Ethnic differences are observed only in UCW, UMW and LMW of Muong vs other groups. Furthermore, Vietnamese children have dental arch width similar to the African and Caucasian.