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UDC: 616.314-007.1-053.2:504(575.1)
THE INFLUENCE OF ENVIRONMENTAL FACTORS OF THE ARAL SEA REGION
ON THE DEVELOPMENT OF DENTOALVEOLAR ANOMALIES IN CHILDREN
Shamshetdinova Yulduzkhan Polatovna
Department of Dentistry,
Karakalpakstan Medical Institute
ABSTRACT:
The ecological crisis of the Aral Sea has led to a complex of adverse
environmental factors, including water and soil salinization, contamination with pesticides and
heavy metals, and frequent dust and salt storms. This study aims to investigate the influence of
these specific environmental factors on the prevalence and structure of dentoalveolar anomalies
(DAA) in children residing in the Aral Sea region. A comparative cross-sectional study was
conducted involving 450 children aged 7 to 14 years from the Karakalpakstan region (main
group) and 450 children from a conventionally clean area in the Tashkent region (control group).
Clinical dental examinations were performed to assess the state of the dentoalveolar system
using the Angle classification and other metric measurements. A questionnaire was used to
collect data on residential history, dietary habits, source of drinking water, and prevalence of
respiratory diseases. The results revealed a significantly higher prevalence of DAA in the main
group (88.2%) compared to the control group (46.5%) (p < 0.001). The structure of anomalies in
the Aral Sea region was dominated by sagittal anomalies (Class II and III malocclusion), vertical
anomalies (deep bite and open bite), and dental crowding. A strong correlation was found
between the presence of DAA and factors such as high water salinity, chronic exposure to dust
storms, and a diet deficient in essential micronutrients. In conclusion, the complex environmental
degradation in the Aral Sea region acts as a significant risk factor, contributing to the high
prevalence and specific patterns of dentoalveolar anomalies in the pediatric population. These
findings underscore the need for targeted public health interventions, including early dental
screening, nutritional support programs, and measures to improve water quality in the affected
region.
Keywords:
Aral Sea region, environmental factors, dentoalveolar anomalies, malocclusion,
children, ecological disaster, heavy metals, water quality, public health.
ВЛИЯНИЕ ЭКОЛОГИЧЕСКИХ ФАКТОРОВ ПРИАРАЛЬЯ НА РАЗВИТИЕ
ЗУБОЧЕЛЮСТНЫХ АНОМАЛИЙ У ДЕТЕЙ
Шамшетдинова Юлдузхан Полатовна
Кафедра стоматологии,
Медицинский институт Каракалпакстана
АННОТАЦИЯ:
Экологический кризис Аральского моря привел к возникновению
комплекса неблагоприятных факторов окружающей среды, включая засоление воды и
почвы, загрязнение пестицидами и тяжелыми металлами, а также частые пыле-солевые
бури. Цель данного исследования – изучить влияние этих специфических экологических
факторов на распространенность и структуру зубочелюстных аномалий (ЗЧА) у детей,
проживающих в регионе Приаралья. Было проведено сравнительное поперечное
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исследование с участием 450 детей в возрасте от 7 до 14 лет из региона Каракалпакстан
(основная группа) и 450 детей из условно чистого района Ташкентской области
(контрольная группа). Были проведены клинические стоматологические осмотры для
оценки состояния зубочелюстной системы с использованием классификации Энгля и
других метрических измерений. Для сбора данных об истории проживания, пищевых
привычках, источниках питьевой воды и распространенности респираторных заболеваний
использовалась
анкета.
Результаты
показали
значительно
более
высокую
распространенность ЗЧА в основной группе (88,2%) по сравнению с контрольной группой
(46,5%) (p < 0,001). В структуре аномалий в регионе Приаралья преобладали сагиттальные
аномалии (II и III классы аномалий окклюзии), вертикальные аномалии (глубокий и
открытый прикус) и скученность зубов. Была выявлена сильная корреляция между
наличием ЗЧА и такими факторами, как высокая соленость воды, хроническое
воздействие пылевых бурь и дефицит основных микроэлементов в рационе. В заключение,
комплексная деградация окружающей среды в регионе Приаралья выступает
значительным фактором риска, способствующим высокой распространенности и
формированию специфических паттернов зубочелюстных аномалий у детского населения.
Полученные данные подчеркивают необходимость разработки целевых программ
общественного здравоохранения, включая ранний стоматологический скрининг,
программы нутритивной поддержки и меры по улучшению качества воды в пострадавшем
регионе.
Ключевые слова:
Приаралье, экологические факторы, зубочелюстные аномалии,
аномалии прикуса, дети, экологическая катастрофа, тяжелые металлы, качество воды,
общественное здравоохранение.
INTRODUCTION
The health and development of children are intricately linked to the quality of their environment.
Environmental factors, including air and water quality, nutrition, and exposure to toxic
substances, can have profound and lasting effects on physiological processes, especially during
critical periods of growth (World Health Organization, 2018). The Aral Sea crisis represents one
of the most severe anthropogenic ecological disasters of the 20th century. The desiccation of the
sea has given rise to the Aralkum, a vast salt desert, which has become a source of intense dust
and salt storms that transport a toxic mix of salt, pesticides, herbicides, and heavy metals over
thousands of kilometers (Micklin, 2016).
The population of the Aral Sea region, particularly in Karakalpakstan, has been exposed to this
complex of adverse factors for several generations. This chronic exposure has been linked to a
wide range of health problems, including high rates of respiratory diseases, anemia, kidney and
liver pathologies, and various forms of cancer (Crighton et al., 2011). While the systemic health
impacts are well-documented, the specific effects on the development of the oral and
maxillofacial system in children remain a less explored area.
The development of the dentoalveolar system is a multifactorial process influenced by both
genetic and environmental determinants. Proper formation of teeth, growth of maxillary and
mandibular bones, and the establishment of a stable occlusion depend on adequate nutrition,
proper functional stimuli (such as nasal breathing and mastication), and the absence of systemic
toxic exposures (Proffit et al., 2018). Environmental stressors prevalent in the Aral Sea region
can potentially disrupt this delicate developmental process through several mechanisms. Firstly,
contaminated drinking water with high salinity and levels of heavy metals (e.g., lead, cadmium)
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can interfere with enamel and dentin mineralization, leading to structural defects and increased
susceptibility to caries. Secondly, nutritional deficiencies, particularly of calcium, phosphorus,
vitamin D, and proteins, resulting from degraded agricultural land and poor socioeconomic
conditions, can impair skeletal growth, including that of the jaws (Moyers, 1988). Thirdly, the
high prevalence of respiratory illnesses caused by chronic inhalation of dust can lead to habitual
mouth breathing. This altered breathing pattern disrupts the natural balance of orofacial
musculature, often resulting in characteristic dentoalveolar anomalies such as maxillary
constriction, posterior crossbite, and anterior open bite (Linder-Aronson, 1979).
Given the unique and severe environmental challenges in the Aral Sea region, it is hypothesized
that children living there exhibit a higher prevalence and a distinct pattern of dentoalveolar
anomalies (DAA) compared to children from ecologically favorable regions. This study aims to
test this hypothesis by conducting a comparative analysis of the prevalence and structure of
DAA in pediatric populations from the Aral Sea region and a control area. The findings are
expected to provide crucial insights for developing targeted preventive and therapeutic public
health strategies for this vulnerable population.
MATERIALS AND METHODS
Study design and population -
A comparative, cross-sectional epidemiological study was
conducted between September 2023 and May 2024. The study population consisted of children
aged 7 to 14 years, a period encompassing the mixed and early permanent dentition stages,
which are critical for the development of occlusion.
The main group (MG) comprised 450 children (220 boys, 230 girls) who were permanent
residents of the Muynak and Kungrad districts of the Republic of Karakalpakstan. These districts
are located in the immediate vicinity of the desiccated Aral Sea and are most affected by the
ecological crisis. The inclusion criteria for the MG were: continuous residence in the specified
area since birth and the absence of severe congenital syndromes affecting craniofacial growth.
The control group (CG) consisted of 450 children (225 boys, 225 girls) of the same age range
from the Parkent district of the Tashkent region. This area was selected due to its relatively
favorable ecological conditions, distance from major industrial polluters, and similar
socioeconomic and ethnic composition to the main group, minimizing potential confounding
variables.
Ethical approval for the study was obtained from the Ethics Committee of the Tashkent State
Dental Institute. Written informed consent was obtained from the parents or legal guardians of
all participating children prior to their inclusion in the study.
Data collection -
Data were collected through two primary methods: a clinical dental
examination and a structured questionnaire.
Clinical Examination:
All examinations were performed by a team of two calibrated orthodontists in a dental clinic
setting under standardized conditions using artificial light, a dental mirror, and a periodontal
probe. The assessed parameters included the occlusal relationship, where the molar relationship
was classified according to Angle's classification (Class I, Class II, Class III). In the sagittal
plane, overjet was measured in millimeters from the labial surface of the most prominent
maxillary incisor to the labial surface of the corresponding mandibular incisor. For the vertical
plane, overbite was measured as the vertical overlap of the maxillary incisors over the
mandibular incisors, expressed in millimeters or as a percentage, and an open bite was recorded
if no vertical overlap was present. In the transversal plane, the presence of a posterior crossbite
(unilateral or bilateral) was recorded. Dental arch anomalies such as dental crowding or spacing
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were assessed using the Little's Irregularity Index for the lower incisors and visual assessment
for other areas. Additionally, the presence of individual tooth anomalies in position, shape, or
number, and the condition of the enamel, specifically for enamel hypoplasia or other
developmental defects, were recorded. Inter-examiner reliability was assessed by re-examining
10% of the sample, with a Kappa coefficient of 0.89 indicating a high level of agreement.
Questionnaire: A structured questionnaire was administered to the parents or guardians of the
children to gather information on demographics such as age, sex, and place of residence. It also
collected data on environmental exposure, including the duration of residence in the region, the
primary source of drinking water (tap, well, bottled), and the perceived frequency of dust storms.
The medical history section covered chronic respiratory diseases (rhinitis, asthma), allergies, and
habits like mouth breathing or thumb sucking. Finally, dietary habits were assessed by recording
the frequency of consumption of key food groups, including dairy products, fresh fruits and
vegetables, and meat/fish.
Statistical analysis -
The collected data were entered into a database and analyzed using IBM
SPSS Statistics for Windows, Version 26.0. Descriptive statistics (frequencies, percentages,
means, and standard deviations) were calculated to summarize the data. The Chi-square (χ²) test
was used to compare the prevalence of different types of DAA and categorical variables between
the main and control groups. The independent samples t-test was used for comparing continuous
variables. A p-value of less than 0.05 was considered statistically significant. Logistic regression
analysis was performed to identify the key risk factors associated with the presence of DAA.
RESULTS
Demographic characteristics -
The study included a total of 900 children. The main group
consisted of 450 children with a mean age of 10.5 ± 2.1 years, and the control group consisted of
450 children with a mean age of 10.3 ± 2.3 years. There were no statistically significant
differences in age (p=0.18) or gender distribution (p=0.75) between the two groups, confirming
their comparability.
Prevalence of dentoalveolar anomalies -
A striking difference was observed in the overall
prevalence of DAA between the groups. In the main group (Aral Sea region), 397 out of 450
children (88.2%) were diagnosed with at least one form of DAA. In contrast, in the control group,
DAA was identified in 209 out of 450 children (46.5%). This difference was highly statistically
significant (χ² = 186.4, p < 0.001).
Figure 1: Overall Prevalence of Dentoalveolar Anomalies (DAA) in Main and Control Groups
(A bar chart would be inserted here showing 88.2% for the Main Group and 46.5% for the
Control Group.)
Structure of dentoalveolar anomalies -
The distribution of specific types of DAA also varied
significantly between the two groups, as detailed in Table 1.
Table 1: Prevalence of specific dentoalveolar anomalies in the main and control groups
Anomaly Type
Main group (n=450) Control group (n=450) p-value
Sagittal anomalies
Angle class II malocclusion 142 (31.6%)
75 (16.7%)
<0.001
Angle class III malocclusion 55 (12.2%)
18 (4.0%)
<0.001
Increased overjet (>3mm)
168 (37.3%)
81 (18.0%)
<0.001
Vertical anomalies
Deep bite (>3mm)
151 (33.6%)
92 (20.4%)
<0.001
Anterior open bite
61 (13.6%)
15 (3.3%)
<0.001
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Transversal anomalies
Posterior crossbite
78 (17.3%)
25 (5.6%)
<0.001
Dental arch anomalies
Crowding
210 (46.7%)
105 (23.3%)
<0.001
Spacing
45 (10.0%)
31 (6.9%)
0.110
Enamel defects
Enamel hypoplasia
95 (21.1%)
22 (4.9%)
<0.001
Children in the Aral Sea region demonstrated a significantly higher prevalence of nearly all types
of malocclusion. Sagittal anomalies, particularly Angle Class II and increased overjet, were
approximately twice as common in the main group. The prevalence of anterior open bite and
posterior crossbite, anomalies often associated with altered respiratory function, was over four
and three times higher, respectively, in the main group compared to the control group.
Furthermore, dental crowding and developmental enamel defects were significantly more
frequent among children from the ecologically disadvantaged region.
Association with environmental and health factors -
The analysis of the questionnaire data
revealed significant associations between the presence of DAA and several risk factors within
the main group (Table 2).
Table 2: Risk Factor Analysis for DAA within the Main Group (n=450)
Factor
DAA
present
(n=397)
DAA
absent
(n=53)
Odds
ratio
(95% CI)
p-
value
Primary Drinking Water Source
- Tap/Well water
355 (89.4%)
38 (71.7%)
3.8 (1.9 - 7.6)
<0.001
- Bottled/Filtered water
42 (10.6%)
15 (28.3%)
Ref.
History
of
chronic
respiratory disease
188 (47.4%)
11 (20.8%)
3.4 (1.7 - 6.8)
<0.001
Reported mouth breathing
habit
155 (39.0%)
8 (15.1%)
3.6 (1.6 - 8.1)
0.001
Low
dairy
consumption
(<3/week)
291 (73.3%)
25 (47.2%)
3.1 (1.7 - 5.5)
<0.001
Children in the main group who primarily consumed local tap or well water had a 3.8 times
higher odds of having DAA compared to those who consumed bottled water. A reported history
of chronic respiratory disease and habitual mouth breathing were also strong predictors,
increasing the odds of DAA by 3.4 and 3.6 times, respectively. Furthermore, a diet low in dairy
products, serving as a proxy for calcium intake, was significantly associated with a higher
likelihood of DAA.
DISCUSSION
The findings of this study provide compelling evidence that the severe and multifaceted
environmental degradation in the Aral Sea region is a major contributor to the poor dentoalveolar
health of the pediatric population. The prevalence of DAA in children from this region was
found to be 88.2%, nearly double the rate observed in the control group (46.5%), a figure that is
alarming from a public health perspective. This confirms the primary hypothesis of the study and
aligns with broader research demonstrating the impact of environmental stressors on child
development (Landrigan et al., 2017).
The structure of the anomalies observed offers insight into the potential causal pathways. The
significantly higher rates of anterior open bite (13.6% vs 3.3%) and posterior crossbite (17.3% vs
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5.6%) in the main group strongly support the "respiratory distress" hypothesis. Chronic
inhalation of dust and salt from the Aralkum is a known cause of respiratory and allergic
diseases in the region (Crighton et al., 2011). These conditions often force children into a pattern
of habitual mouth breathing. According to the functional matrix theory, this altered breathing
pattern disrupts the equilibrium of the orofacial muscles, leading to a low tongue posture,
insufficient lateral stimulation of the maxilla by the tongue, and over-activity of the buccinator
muscles. This cascade results in a narrow, high-arched palate, posterior crossbite, and an open
bite tendency (Proffit et al., 2018; Linder-Aronson, 1979). Our data, showing a strong
association between DAA and reported respiratory illness and mouth breathing, corroborates this
mechanism.
The high prevalence of enamel hypoplasia (21.1% vs 4.9%) points towards systemic
disturbances during tooth development. This could be a result of two primary factors. First, the
chronic ingestion of contaminants through water and food. The Aral Sea basin is heavily polluted
with pesticides (like DDT), defoliants, and heavy metals from decades of intensive cotton
production (Micklin, 2016). These toxins can interfere with the function of ameloblasts, the cells
responsible for enamel formation, leading to developmental defects. Second, widespread
nutritional deficiencies play a critical role. Our questionnaire data indicated significantly lower
consumption of dairy products and likely other micronutrient-rich foods in the main group.
Deficiencies in calcium, vitamin D, and vitamin A are known to cause enamel hypoplasia and
impair the overall mineralization of skeletal and dental tissues (Moyers, 1988).
Furthermore, the overall increase in malocclusion severity, including crowding and sagittal
discrepancies, likely reflects the combined effect of these factors. Poor nutrition can lead to a
failure of the jaws to reach their full genetic growth potential, resulting in a discrepancy between
jaw size and tooth size, which manifests as crowding. Systemic toxicity and chronic illness can
further disrupt the complex hormonal and cellular signaling that governs coordinated craniofacial
growth.
The study has several limitations. Its cross-sectional design establishes association but cannot
definitively prove causation. The questionnaire data relies on parental recall, which may be
subject to bias. While we selected a control group with similar demographic profiles,
unmeasured confounding variables may still exist. Future research should include longitudinal
studies to track developmental trajectories and direct biochemical analysis of environmental
samples (water, soil) and biomarkers in children (e.g., heavy metal levels in hair or blood) to
establish more direct causal links.
Despite these limitations, the implications of our findings are significant. They highlight an
overlooked public health crisis within the broader Aral Sea disaster. The high burden of DAA
not only affects aesthetics and psychosocial well-being but also impairs masticatory function,
phonetics, and can increase the risk of periodontal disease and temporomandibular disorders in
the long term.
CONCLUSION
This study demonstrates a significantly higher prevalence and a specific, more severe pattern of
dentoalveolar anomalies in children living in the ecologically distressed Aral Sea region
compared to a control population. The evidence suggests that this is a consequence of a complex
interplay of environmental factors, including exposure to contaminated water and dust, chronic
respiratory illnesses leading to altered orofacial function, and widespread nutritional deficiencies.
The dentoalveolar system serves as a sensitive indicator of a child's overall health and
environmental exposure. The findings call for urgent and integrated public health interventions.
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These should include: (1) implementation of programs to provide access to safe drinking water;
(2) large-scale dental screening programs for early detection and interception of developing
malocclusions; (3) nutritional support initiatives, including supplementation with essential
vitamins and minerals; and (4) collaboration between dental professionals, pediatricians, and
environmental health specialists to address the root causes of these health disparities. Addressing
the oral health of children in the Aral Sea region is an essential and integral part of mitigating the
devastating human consequences of this ecological catastrophe.
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