Effects of fetal exposure to nicotine on dental development of the laboratory rat

Protocol for CARES-HAPIN: an ambidirectional cohort study on exposure to environmental tobacco smoke and risk of early childhood caries

INTRODUCTION

Prenatal and postnatal exposure to environmental tobacco smoke (ETS) has been linked with early childhood caries (ECC), but the specific molecular mechanisms and pathways remain largely unknown. The Caries Risk from exposure to Environmental tobacco Smoke (CARES) within the Household Air Pollution Intervention Network (HAPIN) study aims to establish the association between ETS and ECC by employing epidemiological and novel biomarker-based approaches. Here, we outline the overall design and rationale of the project.

METHODS AND ANALYSIS

We will leverage the infrastructure and data from the HAPIN trial (India) to mount the CARES study. In this ambidirectional cohort study, children (n=735, aged: 3-5 years) will undergo ECC examination by a trained dentist using standard criteria and calibrated methods. Structured questionnaires will be used to gather information on sociodemographic variables, dietary habits, oral hygiene, oral health-related quality of life and current exposure to ETS. We will collect non-invasive or minimally invasive biospecimens (i.e., saliva, buccal cells, dried blood spots and urine) from a subset of HAPIN children (n=120) to assess a battery of biomarkers indicative of exposure to ETS, early biological effect and epigenetic modifications. Both self-reported and objective measures of ETS exposure collected longitudinally during in utero and early postnatal periods will be accessed from the HAPIN database. We will apply current science data techniques to assess the association and interrelationships between ETS, ECC, and multiple biomarkers.

ETHICS AND DISSEMINATION

Information gathered in this research will be published in peer-reviewed journals and summaries will be shared with the key stakeholders as well as patients and their parents/guardians involved in this study. Sri Ramachandra Institute of Higher Education and Research Ethics Board has approved the study protocol (IEC-NI22/JUL/83/82).

TRIAL REGISTRATION NUMBER

NCT02944682.

Indoor Household Exposures and Associated Morbidity and Mortality Outcomes in Children and Adults in South Africa

Human exposure to indoor pollution is one of the most well-established ways that housing affects health. We conducted a review to document evidence on the morbidity and mortality outcomes associated with indoor household exposures in children and adults in South Africa. The authors conducted a scientific review of the publicly available literature up to April 2022 using different search engines (PubMed, ProQuest, Science Direct, Scopus and Google Scholar) to identify the literature that assessed the link between indoor household exposures and morbidity and mortality outcomes in children and adults. A total of 16 studies with 16,920 participants were included. Bioaerosols, allergens, dampness, tobacco smoking, household cooking and heating fuels, particulate matter, gaseous pollutants and indoor spray residue play a significant role in different morbidity outcomes. These health outcomes include dental caries, asthma, tuberculosis, severe airway inflammation, airway blockage, wheeze, rhinitis, bronchial hyperresponsiveness, phlegm on the chest, current rhinoconjunctivitis, hay fever, poor early life immune function, hypertensive disorders of pregnancy, gestational hypertension, and increased incidence of nasopharyngeal bacteria, which may predispose people to lower respiratory tract infections. The findings of this research highlight the need for more initiatives, programs, strategies, and policies to better reduce the negative consequences of indoor household exposures.

Influence of life-style factors, including second-hand smoke, on dental caries among 3-year-old children in Wuxi, China

AIM

To examine the association of life-style factors, including second-hand smoke, with dental caries among 3-year-old children in Wuxi, China.

METHODS

A multi-stage stratified random cluster sampling method was used, and 283 children were recruited. The prevalence of dental caries was 29.3% (83/283).

RESULTS

Univariate analysis indicated that the possible related factors of dental caries included sleep duration, interest in snacks, candy, exposure to second-hand smoke and weight of birth (all P < 0.05). Meanwhile, multivariate logistic regression analysis suggested that children who had used fluoride were less susceptible to dental caries than those who had not used fluoride before (P < 0.05). Moreover, the risk of dental caries in children who were very interested in snacks was greater than those with little interest in snacks (P < 0.05).

CONCLUSIONS

Life-style behaviours are crucial factors and should attract enough attention. There might be a potential negative effect of second-hand smoke on the deciduous caries, but it still requires further studies. A co-ordinated effort by health-care providers, policymakers and health institutions has successfully improved children's oral health and the awareness of hygiene knowledge among citizens in Wuxi city.

Effects of nicotine exposure on murine mandibular development

Nicotine is known to affect cell proliferation and differentiation, two processes vital to proper development of the mandible. The mandible, the lower jaw in mammals and fish, plays a crucial role in craniofacial development. Malformation of the jaw can precipitate a plethora of complications including disrupting development of the upper jaw, the palate, and or impeding airway function. The purpose of this study was to test the hypothesis that in utero nicotine exposure alters the development of the murine mandible in a dose dependent manner. To test this hypothesis, wild type C57BL6 mice were used to produce in utero nicotine exposed litters by adding nicotine to the drinking water of pregnant dams at concentrations of 0 μg/ml (control), 50 μg/ml (low), 100 μg/ml (medium), 200 μg/ml (high) throughout pregnancy to birth of litters mimicking clinically relevant nicotine exposures. Resultant pups revealed no significant differences in body weight however, cephalometric investigation revealed several dimensions affected by nicotine exposure including mandibular ramus height, mandibular body height, and molar length. Histological investigation of molars revealed an increase in proliferation and a decrease in apoptosis with nicotine exposure. These results demonstrate the direct effects of nicotine on the developing mandible outside the context of tobacco use, indicating that nicotine use including tobacco alternatives, cessation methods, and electronic nicotine delivering products may disrupt normal growth and development of the craniofacial complex.

Association between passive tobacco exposure and caries in children and adolescents. A systematic review and meta-analysis

To examine the available evidence on the association between exposure to tobacco use in the womb and in infancy and the presence of caries in primary and permanent dentition in children and adolescents.

A systematic review was conducted through searches in 4 data bases (Pubmed, Scopus, Embase and Web of Science), complemented by hand-searching. Of the 559 articles identified, 400 were duplicates. Finally, 28 articles were included in the qualitative review and 21 in the meta-analysis. Their quality was assessed using the Newcastle-Ottawa scale. The quality was medium in 44% of the articles included and high in 56%.

The overall meta-analysis gave a significant odds ratio (OR = 1.53, 95% confidence interval 1.39–1.68, Z test p-value = 0.000) and high heterogeneity (Q = 200.3, p = 0.000; I² = 86.52%). Separate meta-analyses were also performed for three subgroups: exposure in the womb (prenatal) and caries in primary dentition, which resulted in a significant OR = 1.46 with a 95% CI of 1.41–1.52 (Z test p = 0.000), without heterogeneity (Q = 0.91, p = 0.824; I² = 0%); exposure in infancy (postnatal) and caries in primary dentition, with OR = 1.72 (95% CI 1.45–2.05) and high heterogeneity (Q = 76.59, p = 0.00; I² = 83.01%); and postnatal exposure and caries in permanent dentition, with OR = 1.30 (95% CI 1.25–1.34) and no heterogeneity (Q = 4.48, p = 0.880; I² = 0%). In children and adolescents, a significant though moderate association was found between passive tobacco exposure and caries.

Association between secondhand smoke exposure and early eruption of deciduous teeth: a cross-sectional study

INTRODUCTION

Secondhand smoke (SHS) exposure is a risk factor for early childhood caries. Here we examined the association between SHS exposure and early tooth eruption (ETE) to clarify the additional etiology of an increased chance of contact between the tooth’s surface and acid produced by fermenting oral bacteria.

METHODS

Data of 388 child–mother pairs who attended health checkups at public health centers were assessed for children aged ≥18 months. SHS exposure was reported as maternal smoking during pregnancy and household smoking after birth. Associations between SHS exposure and ETE (≥3 canines in the oral cavity) were tested using multivariable analyses of the dose-response relationship. Subgroup and sensitivity analyses were performed for birth-weight subgroups and SHS exposure variables, respectively.

RESULTS

ETE prevalence was 65.5%, 68.1%, and 76.9% in the no, medium-dose (ceased partway and sometimes), and highest-dose (every day) exposure groups, respectively, during pregnancy, and 61.5%, 75.0%, and 75.5%, respectively, after birth. The association between the highest dose exposure during pregnancy and ETE was not significant (OR=1.42, 95% CI: 0.34–5.96, p=0.631), whereas that between highest dose exposure after birth and ETE was significant (OR=2.13, 95% CI: 1.06–4.31, p=0.034); this association was distinct in the subgroup of children with smaller birth weights (<3000 g) (OR=3.19, 95% CI: 1.08–9.44, p=0.036). The dose-response relationship was consistently significant for exposure after birth (p<0.05). The sensitivity analysis that employed no SHS exposure, as a reference, revealed that exposure after birth but no exposure during pregnancy was significantly associated with ETE (OR=2.29, 95% CI: 1.19–4.40, p=0.013). However, the association between exposure during pregnancy and ETE was consistently non-significant (p>0.05).

CONCLUSIONS

When controlling for variables of birth weight and exposure type, SHS exposure after birth was independently associated with the early eruption of deciduous canines. Further studies are warranted to examine the trajectory of SHS exposure after birth, ETE, and early childhood caries incidence.

ABBREVIATIONS

ETE: Early tooth eruption, SHS: Secondhand smoke

Physical, behavioral, and cognitive effects of prenatal tobacco and postnatal secondhand smoke exposure

The purpose of this review is to examine the rapidly expanding literature regarding the effects of prenatal tobacco and postnatal secondhand smoke (SHS) exposure on child health and development. Mechanisms of SHS exposure are reviewed, including critical periods during which exposure to tobacco products appears to be particularly harmful to the developing fetus and child. The biological, biochemical, and neurologic effects of the small fraction of identified components of SHS are described. Research describing these adverse effects of both in utero and childhood exposure is reviewed, including findings from both animal models and humans. The following adverse physical outcomes are discussed: sudden infant death syndrome, low birth weight, decreased head circumference, respiratory infections, otitis media, asthma, childhood cancer, hearing loss, dental caries, and the metabolic syndrome. In addition, the association between the following adverse cognitive and behavioral outcomes and such exposures is described: conduct disorder, attention-deficit/hyperactivity disorder, poor academic achievement, and cognitive impairment. The evidence supporting the adverse effects of SHS exposure is extensive yet rapidly expanding due to improving technology and increased awareness of this profound public health problem. The growing use of alternative tobacco products, such as hookahs (a.k.a. waterpipes), and the scant literature on possible effects from prenatal and secondhand smoke exposure from these products are also discussed. A review of the current knowledge of this important subject has implications for future research as well as public policy and clinical practice.

Dental hospital admissions in the children of mothers with an alcohol-related diagnosis: a population-based, data-linkage study

OBJECTIVE

To investigate the relationship between maternal alcohol-use disorder and dental hospital admissions in children up to 5 years of age.

STUDY DESIGN

Mothers with an International Classification of Diseases, 9th revision/10th revision alcohol-related diagnosis, a proxy for alcohol-use disorder, were identified through the Western Australian data-linkage system. Exposed mothers were frequency-matched by maternal age, Aboriginal status, and child's birth year to randomly selected comparison mothers without an alcohol diagnosis. Linkage with the Midwives Notification System (1983-2002) identified all births of these mothers; "exposed" (non-Aboriginal, n = 11,171; Aboriginal, n = 8145) and comparison cohorts (non-Aboriginal, n = 32,508; Aboriginal, n = 16,719). Dental hospital admissions were identified through linkage with Hospital Morbidity Data (1983-2007) (3.2% exposed; 3.0% comparison) and cases of fetal alcohol syndrome (n = 84) through linkage with the Western Australian Register of Developmental Anomalies. ORs and 95% CIs for having a dental admission (International Classification of Diseases, 9th revision: 520-529; International Classification of Diseases, 10th revision: K0-K14.9) were generated by the use of generalized estimating equations, which we adjusted for potential confounding factors (aOR).

RESULTS

Children of mothers with an alcohol-related diagnosis had increased adjusted odds of gingivitis and periodontal diseases (aOR 1.67; 95% CI 1.12-2.51) and "other" diseases of the lip and oral mucosa (aOR 1.56; 95% CI 1.21-2.01). Diseases of the salivary glands were increased only in Aboriginal children of mothers with an alcohol-related diagnosis (aOR 2.65; 95% CI 1.09-6.44). Children diagnosed with fetal alcohol syndrome had increased ORs of any dental admission (aOR 2.58; 95% CI 1.30-5.11).

CONCLUSIONS

Maternal alcohol-use disorder was associated with dental admissions related to disorders of the soft tissues, but questions remain regarding perinatal influences on dental admissions and disease.

Molar incisor hypomineralisation: possible aetiological factors in children from urban and rural areas

AIM

To analyse factors potentially associated with molar incisor hypomineralisation (MIH) development. METH¬ODS: A population-based study was carried out with 903 children aged from 6-12 years old, born and residing in rural and urban areas of the town of Botelhos, State of Minas Gerais, Brazil. Their mothers completed a structured medical history questionnaire, from pregnancy to the child's 3rd year of life. Two examiners evaluated children for MIH according to criteria suggested by the European Academy of Paediatric Dentistry. Descriptive analyses of the data and odds ratios (OR) with 95% test-based confidence intervals (CI) were estimated. Chi-square test was used to evaluate the differences between groups.

RESULTS

The prevalence of MIH in children from rural area (RA) was significantly higher than those from the urban area (UA) (24.9% versus 17.8%, p= 0.01). In urban children, neither significant associations with MIH nor medical problems were found. In rural children, however, MIH was significantly more common among those whose mothers had experienced medical problems during pregnancy (OR=2.11; 1.01-4.37 CI 95%; p=0.04), who had throat infections (OR=2.93; 1.47-5.87 CI 95%; p=0.01), who had high fever (OR=1.91; 1.07-3.39 CI 95%; p=0.02), and who had used amoxicillin associated with other antibiotics (OR=1.92; 1.02-3.62 CI 95%; p=0.04) during the first 3 years of life.

CONCLUSION

This study suggests a link between MIH and health problems during pregnancy, as well as environmental factors.

Detrimental effects of maternal lead exposure during pregnancy and lactation on molar development in the young rat

The purpose of this animal study was to investigate the influence of maternal lead exposure during pregnancy and lactation on molar development in the offspring. Scanning electron microscopy revealed no significant differences in the molar morphology among the groups. However, in all the experimental groups, deep, wide cracks were found in the occlusal enamel. Further, the experimental groups had smaller molar diameters than the control group, lead exposure during lactation had a greater influence on the molar size in the offspring, and the groups with the higher dose of lead exposure during pregnancy and lactation had significantly smaller molar sizes than the groups that received the lower dose. The mesiodistal and buccolingual diameters of molars were measured as 3.10 ± 0.07 and 1.95 ± 0.04 mm for control group, 2.97 ± 0.08 and 1.94 ± 0.01 mm for lactation group of low dose, 2.96 ± 0.05 and 1.84 ± 0.02 mm for lactation group of high dose, 3.09 ± 0.06 and 1.94 ± 0.04 mm for pregnancy group of low dose, and 3.02 ± 0.06 and 1.85 ± 0.06 mm for pregnancy group of high dose, respectively.

Nicotinic receptor Alpha7 expression during tooth morphogenesis reveals functional pleiotropy

The expression of nicotinic acetylcholine receptor (nAChR) subtype, alpha7, was investigated in the developing teeth of mice that were modified through homologous recombination to express a bi-cistronic IRES-driven tau-enhanced green fluorescent protein (GFP); alpha7GFP) or IRES-Cre (alpha7Cre). The expression of alpha7GFP was detected first in cells of the condensing mesenchyme at embryonic (E) day E13.5 where it intensifies through E14.5. This expression ends abruptly at E15.5, but was again observed in ameloblasts of incisors at E16.5 or molar ameloblasts by E17.5–E18.5. This expression remains detectable until molar enamel deposition is completed or throughout life as in the constantly erupting mouse incisors. The expression of alpha7GFP also identifies all stages of innervation of the tooth organ. Ablation of the alpha7-cell lineage using a conditional alpha7Cre×ROSA26-LoxP(diphtheria toxin A) strategy substantially reduced the mesenchyme and this corresponded with excessive epithelium overgrowth consistent with an instructive role by these cells during ectoderm patterning. However, alpha7knock-out (KO) mice exhibited normal tooth size and shape indicating that under normal conditions alpha7 expression is dispensable to this process. The function of ameloblasts in alpha7KO mice is altered relative to controls. High resolution micro-computed tomography analysis of adult mandibular incisors revealed enamel volume of the alpha7KO was significantly reduced and the organization of enamel rods was altered relative to controls. These results demonstrate distinct and varied spatiotemporal expression of alpha7 during tooth development, and they suggest that dysfunction of this receptor would have diverse impacts upon the adult organ.

Does secondhand smoke affect the development of dental caries in children? A systematic review

This review evaluated evidence of the relationship between secondhand smoke (SHS) and dental caries in children in epidemiological studies. Relevant literature was searched and screened, and the methodological quality was assessed. The search yielded 42 citations. High-quality studies including one cohort format and 14 case-control format studies were selected. Early childhood caries was examined in 11 studies. The independent association of SHS was significant in 10 studies, and the strength was mostly weak to moderate. One study did not select SHS as a significant variable. Three studies reported decreases in the risk of previous exposure, and the association was not significant. Dose-response relationships were evident in five studies. Permanent teeth were examined in seven studies. Five studies reported significant associations, which were mostly weak. The risk of previous exposure remained similar to that of current exposure, and a dose-response relationship was not evident in one study. The overall evidence for the causal association in early childhood caries is possible regarding epidemiological studies, and the evidence of permanent teeth and the effect of maternal smoking during pregnancy were insufficient. The results warrant further studies of deciduous teeth using a cohort format and basic studies regarding the underlying mechanism.

The morphology and mineralization of dental hard tissue in the offspring of passive smoking rats

OBJECTIVE

To study the effects of maternal passive smoking on the morphology and mineralization of dental hard tissue in offspring rats.

DESIGN

We have established a maternal passive smoking model. Offspring rats were sacrificed on the 20th day of gestation (E20) or the 3rd (D3) or 10th day (D10) after birth. We observed hard tissue morphology using Haematoxylin-Eosin (H&E) staining sections, used micro computer tomography (Micro-CT) to measure hard tissue thickness and volume on the mandibular first molars of the offspring rats, and used Micro-CT and energy dispersive X-ray spectroscopy with scanning electron microscopy (SEM/EDS) to determine the hard tissue mineral density and the ratio of calcium atom number/calcium atom+phosphorus atom number (Ca(2+)/P(3-)+Ca(2+)).

RESULTS

Overall, the development of dental hard tissue was delayed in the offspring of passive smoking rats. The thickness and volume of hard tissue were lower in the offspring of the maternal passive smoking group than in the offspring of the control group. Mineral density of the hard tissue and the ratio of (Ca(2+)/P(3-)+Ca(2+)) were also reduced in the offspring of the maternal passive smoking group.

CONCLUSION

Maternal passive smoking inhibits the morphological development and mineralization level of hard tissue on the mandibular first molars of offspring rats.

Association of passive smoking with caries and related salivary biomarkers in young children

OBJECTIVE

To investigate the association between passive smoking, as determined by salivary cotinine level, and caries, salivary pH, buffering capacity, flow rate and microbiological counts in young children.

DESIGN

Ninety passive smokers (PS) with a mean age of 5.02 years and 90 healthy age-matched controls were included in this study. Family income, smoking habits of household members, parental education levels, child's tooth-brushing habit and child's daily dietary sugar exposure were recorded by questionnaire. Three categories were formed with respect to the number of cigarettes smoked. A dmft score was calculated according to the criteria recommended by the World Health Organization. The children were also investigated for stimulated salivary cotinine level, pH, flow rate, buffering capacity and salivary Streptococcus mutans and lactobacilli colonisation.

RESULTS

There were no significant differences in tooth-brushing habit, sugar exposure, family income and parental education levels between the two groups (P>0.05). The mean cotinine level of the PS subjects was 1.58+/-4.3ng/ml. The dmft scores, and salivary S. mutans and lactobacilli colonisation in PS children were significantly higher than in the control subjects (P<0.05). Statistically significant decreases in salivary pH, flow rate and buffering capacity were found in the PS subjects (P<0.05).

CONCLUSION

PS children are at increased risk of caries compared with control subjects.

Fluctuating asymmetry as an animal welfare indicator -- a review of methodology and validity

It has been suggested that fluctuating asymmetry (FA) reflects an animal's ability to cope with the sum of challenges during its growing period and, thus, is a potential welfare indicator. In this review we investigate the evidence of associations between FA and other welfare indicators measured at the level of the individual and of effects of welfare-relevant environmental conditions on FA in populations of captive birds and mammals including humans. As the question of validity cannot be treated independently from the quality of the available data, first a checklist for the proper measurement and analysis of FA is drafted and used to evaluate the methodological quality of the various studies. We recommend this checklist to be used as a standard for future FA studies. We found 17 relevant studies on associations between FA and other welfare indicators, and 36 studies on effects of welfare-relevant factors on FA. Frequent methodological shortcomings or insufficient methodological information allow for only cautious conclusions. The proportion of significant results supporting the link between higher FA and poorer welfare is only moderately high. Independent from statistical significance, almost all studies found the relationship between FA and welfare to be prevailingly in the expected direction. FA is a promising measure of animal welfare, despite a great number of open questions, e.g. relating to the ontogeny of FA or its sensitivity to various stressors. The considerable potential of FA as a welfare indicator makes it worthwhile to pursue more intensely validation studies as well as applied studies. These studies should pay particular attention to an appropriate methodological approach.

Morphological alterations in the epithelium of the oral mucosa of rats (Rattus norvegicus) submitted to long-term systemic nicotine treatment

Smoking is considered to be the most albeit preventable cause of diseases and premature deaths in the history of mankind. The local action of tobacco on the oral mucosa can cause precancerous and cancerous lesions. However, there is not enough evidence to establish all the systemic effects caused by nicotine on the organism. Thus, the aim of the present study was to characterize the cellular changes of the cheek mucosa of rats submitted to long-term systemic nicotine treatment. Twenty male rats were divided into two experimental groups: a nicotine group and a control group, each consisting of 10 animals. The nicotine group was injected daily with 0.250 mg of nicotine per 100 g of body weight. All animals received a solid diet and water ad libitum. After 90 days of treatment, all animals were weighed and sacrificed. Samples of cheek mucosa were collected for light and transmission electron microscopy. The results revealed oral epithelium containing atypical cells that were characterized by atrophy, cell membrane disorganization and tissue damage. It was concluded that systemic administration of nicotine damaged the cellular integrity of the oral mucosa, impairing tissue function and predisposing the tissue to the action of different pathogenic agents and also to that of other carcinogenic substances present in tobacco.

Morphometric and morphological features of the ventral prostate in rats submitted to chronic nicotine and alcohol treatment

Clinical studies analyzing simultaneous nicotine-alcohol use by patients showed important alterations in various organic systems such as: respiratory, digestory, and genital. Also, the prostatic morphology and physiology have been analyzed, specially due to large occurrence of prostatic diseases. Then, this work aimed at determining the structure and ultrastructure of the prostatic stroma and epithelium, as well as the stroma epithelium interactions from rats submitted to simultaneous long-term alcohol-nicotine treatment. A total of 40 male rats were divided into four groups: control group (10 animals) received tap water; alcoholic group (10 animals) received diluted 10% Gay Lussac ethanol; nicotine group (10 animals) received a 0.125mg/100g of body weight dose of nicotine injected subcutaneosly on a daily basis; nicotine-alcohol group (10 animals) received simultaneous alcohol and nicotine treatment. After 90 days of treatment, the animals were sacrificed and samples from the ventral lobe of the prostate were collected and processed for transmission electron and light microscopies. The results showed atrophied epithelium; prostatic intra-epithelial neoplasia; dilated cisterns of the granular endoplasmic reticulum, large amounts of collagen fibers besides inflammatory cells, specially in the alcoholic and nicotine-alcohol groups. Therefore, it could be concluded that the association between alcohol and nicotine caused the impairment of the prostatic secretory process. Moreover, this association is related to prostatic pathogenesis, which could lead to late glandular malignancy.

Morphometric and ultrastructure features of the ventral prostate of rats (Rattus norvegicus) submitted to long-term nicotine treatment

The harmful effects of nicotine on male genital system fertility have been reported in experimental and clinical studies. However, its effects on prostatic cells and glandular pathogenesis remain unclear. The aim of the present study was to analyse the histological, histochemical and ultrastructural alterations, in addition to stereology, of the ventral lobe of the prostate of rats, submitted to chronic nicotine administration, as well as to establish the relationship between these changes and prostate diseases. Twelve male Wistar rats (Rattus norvegicus) were divided into two experimental groups: group I (nicotine) and group II (control). Samples of the ventral prostate were collected, processed and submitted to histological analysis, acid phosphatase histochemistry and ultrastructural analysis by transmission and scanning electron microscopies. The results showed that in the nicotine group, the secretory epithelial cells of the ventral lobe of the prostate were atrophied, and prostatic intraepithelial neoplasia occurred and reduced the expression of acid phosphatase. The disorganisation of organelles involved in the glandular secretory process, accompanied by biomembrane destructuring, was also observed. In conclusion, nicotine causes drastic alterations in the secretory epithelium of the ventral prostate, compromising its function. Furthermore, nicotine also induces premalignant lesions in the prostate gland, thus representing a risk factor in the development of prostate diseases.

7,12-Dimethylbenz[a]anthracene Interferes with the Development of Cultured Mouse Mandibular Molars

Clinical studies suggest that maternal smoking during pregnancy can reduce the crown size of the child's teeth. Delayed dental age compared with chronological age has also been reported in children whose parents smoke. Among the main components of tobacco smoke are nonhalogenated polycyclic aromatic hydrocarbons (PAHs), many of which are highly toxic. Humans are exposed to PAH compounds mainly via tobacco smoke and diet. The aim of our study was to investigate the effect of PAHs on tooth formation and the function of tooth-forming cells. We exposed mouse (NMRI) E18 mandibular first and second molar explants to 7,12-dimethylbenz[a]anthracene (DMBA), a toxic PAH compound, in organ culture for 7 or 12 days. DMBA concentrations used were 0.1, 0.5, 1, and 2 microM. The mesiodistal width of each first molar (12-day culture) was measured in stereomicroscopic images, and the teeth were analysed histologically. DMBA exposure significantly reduced the mesiodistal width of the first molars. DMBA impaired or delayed amelogenesis and dentinogenesis in both molars at the lowest concentration of 0.1 microM. DMBA affected enamel formation more severely than dentin formation and occasionally prevented amelogenesis completely. Elongation and polarization of ameloblasts were impaired, and blood vessel architecture of the dental papilla (future pulp) was altered. Cusps were thin and sharp. In line with the finding that maternal smoking during pregnancy has an adverse effect on child's tooth development, this study shows the toxic influence of PAHs on tooth development in vitro.