Dental pain report in children and genetic polymorphism (rs4818) in Catechol-O-Methyltransferase (COMT) gene: a cross- sectional study

Abstract Aim: Polymorphisms in the COMT gene can alter enzymatic functions, raising levels of endogenous catecholamines, which stimulates beta-adrenergic receptors related to pain. This study aimed to evaluate whether a polymorphism in the COMT gene (rs4818) is associated with dental pain in children. Methodology: A cross-sectional study was conducted with a representative sample of 731 pairs of children and parents randomly selected from a population-based sample of eight-year-old children. Reports of dental pain was evaluated using a question directed at the parents and self-reported pain using the Faces Pain Scale - Revised. Dental caries experience was determined using the Decayed, Missing, and Filled Teeth (DMFT) index. For genetic analysis, DNA was obtained from oral mucosa epithelial cells of 352 children randomly selected from the initial sample. Results: Children with the CC genotype had higher odds of reporting moderate to intense pain than those with the GG genotype (OR=3.60; 95% CI=0.80-16.20; p=0.03). These same children had greater odds of parental reports of pain (OR=1.93; 95% CI=0.91-4.08; p=0.02). Moreover, lower schooling of parents/guardians and caries experience in the primary dentition were significantly associated with greater odds of a parental report of dental pain (OR=2.06; 95% CI=1.47-2.91; p<0.001; OR=6.26; 95% CI=4.46-8.78; p<0.001). Conclusions: The rs4818 polymorphism of the COMT gene is associated with dental pain. Children with the C allele are more likely to report higher levels of pain. Clinical Relevance: Even though the experience of pain is subjective and multifactorial, this study raises the hypothesis that there is a genetic predisposition to dental pain that should be considered in clinical practice.

Association of defects of enamel with polymorphisms in the vitamin D receptor and parathyroid hormone genes

Abstract This cross-sectional study aimed to investigate the association between developmental defects of enamel (DDE) and single nucleotide polymorphisms (SNPs) in the genes encoding the vitamin D receptor (VDR) and parathyroid hormone (PTH). Orthodontic patients receiving treatment at a dental school were selected through convenience sampling. Intra-oral photographs were used to assess DDE, which were classified according to the criteria proposed by Ghanim et al. (2015) by a single calibrated examiner (Kappa>0.80). Enamel hypoplasia, molar-incisor hypomineralization (MIH), hypomimineralized second primary molar (HSPM), and non-MIH/HSPM demarcated opacities were considered for the analysis. Genomic DNA was extracted from buccal cells. The SNPs in VDR (rs7975232) and PHT (rs694, rs6256, and rs307247) were genotyped using real-time polymerase chain reactions (PCR). Statistical analyses were performed using the PLINK software (version 1.03, designed by Shaun Purcell, EUA). Chi-square or Fisher's exact tests were performed at a significance level of 5%. Ninety-one (n=91) patients (49 females and 42 males) (mean age of 14.1±5.8 years) were included. The frequency of DDE was 38.5% (35 patients). Genotype distributions were in Hardy-Weinberg equilibrium. No significant statistical association was found between DDE and the SNPs evaluated. A borderline association (p=0.09) was observed between DDE and the CC haplotype for SNP rs7975232 in VDR. In conclusion, the selected SNPs in VDR and PTH genes were not associated with DDE in the studied samples.

Resumo Este estudo transversal teve como objetivo investigar a associação entre defeitos de desenvolvimento do esmalte (DDE) e polimorfismos de nucleotídeo único (SNPs) nos genes que codificam o receptor da vitamina D (VDR) e o hormônio da paratireoide (PTH). Pacientes ortodônticos em tratamento em uma escola Odontologia foram selecionados por amostragem de conveniência. Os DDEs foram avaliados e classificados por um examinador calibrado (Kappa>0,80) através de fotografias intraorais de acordo com os critérios propostos por Ghanim et al. (2015). Os tipos de DDE considerados para análise foram: hipoplasia de esmalte, hipomineralização molar-incisivo (HMI), hipomineralização de segundos molares decíduos (HSMD) e opacidades demarcadas não-HMI/HSMD. O DNA gnômico foi extraído de células bucais. Os SNPs em VDR (rs7975232) e PTH (rs694, rs6256 e rs307247) foram genotipados por PCR em tempo real. As análises estatísticas foram realizadas utilizando o software PLINK (versão 1.03, concebido por Shaun Purcell, EUA). Foram feitos teste de qui-quadrado e teste exato de Fisher com um nível de significância de 5%. Foram incluídos noventa e um (n=91) pacientes (49 do sexo feminino e 42 do sexo masculino) (idade média de 14,1±5,8 anos). A frequência de DDE foi de 38,5% (35 pacientes). As distribuições genotípicas estavam em equilíbrio de Hardy-Weinberg. Não foi encontrada associação estatisticamente significante entre os DDEs e os SNPs avaliados. Foi observada uma associação limítrofe (p=0,09) entre a DDE e o haplótipo CC para o SNP rs7975232 no VDR. Em conclusão, os SNPs seleccionados nos genes VDR e PTH não foram associados à DDE nas amostras estudadas.

What are the Systemic Factors Associated with the Molar-Incisor Hypomineralization Etiology?

ABSTRACT Objective: To evaluate the systemic factors associated with Molar-Incisor Hypomineralization (MIH) etiology. Material and Methods: A total of 731 8-year-old schoolchildren enrolled in the public school system in Curitiba, Brazil, was randomly selected. The MIH diagnosis was performed by calibrated examiners (Kappa >0.80) according to the European Academy of Pediatric Dentistry criteria (2003). The systemic factors were collected through a semi-structured questionnaire and applied to the children's mothers, addressing the medical history from pregnancy to the first three years of children's life. Associations were analyzed by Poisson regression analysis with robust variance (p<0.05). Results: The systemic factors in the prenatal and perinatal periods were not associated with MIH (p>0.05). The children who used medications during the first years of life had a significantly higher prevalence of MIH (PRc = 2.18 CI = 95% 1.06-4.48; p=0.033). Conclusion: The use of medications during the first three years of children's life is associated with a higher prevalence of MIH.

In vivo effect of fluoride combined with amoxicillin on enamel development in rats

Abstract Some evidence in vitro suggested that amoxicillin and fluoride could disturb the enamel mineralization. Objective: To assess the effect of amoxicillin and of the combination of amoxicillin and fluoride on enamel mineralization in rats. Methodology: In total, 40 rats were randomly assigned to four groups: control group (CG); amoxicillin group (AG - amoxicillin (500 mg/kg/day), fluoride group (FG - fluoridated water (100 ppm -221 mg F/L), and amoxicillin + fluoride group (AFG). After 60 days, the samples were collected from plasma and tibiae and analyzed for fluoride (F) concentration. The incisors were also collected to determine the severity of fluorosis using the Dental Fluorosis by Image Analysis (DFIA) software, concentration of F, measurements of enamel thickness, and hardness. The data were analyzed by ANOVA, Tukey's post-hoc test, or Games-Howell post-hoc test (α=0.05). Results: Enamel thickness of the incisors did not differ statistically among the groups (p=0.228). Groups exposed to fluoride (AFG and FG) have higher F concentrations in plasma, bone and teeth than those not exposed to fluoride (CG and AG). The groups showed a similar behavior in the DFIA and hardness test, with the FG and AFG groups showing more severe fluorosis defects and significant lower hardness when compared with the AG and CG groups, with no difference from each other. Conclusion: The rats exposed to fluoride or fluoride + amoxicillin developed dental fluorosis, while exposure to amoxicillin alone did not lead to enamel defects.

The effect of amoxicillin on dental enamel development in vivo

Abstract The exposure to amoxicillin has been associated with molar incisor hypomineralization. This study aimed to determine if amoxicillin disturbs the enamel mineralization in in vivo experiments. Fifteen pregnant rats were randomly assigned into three groups to received daily phosphatase-buffered saline or amoxicillin as either 100 or 500 mg/kg. Mice received treatment from day 13 of pregnancy to day 40 postnatal. After birth, the offsprings from each litter continued to receive the same treatment according to their respective group. Calcium (Ca) and phosphorus (P) content in the dental hard tissues were analyzed from 60 upper first molars and 60 upper incisors by the complexometric titration method and colorimetric analysis using a spectrophotometer at 680 nm, respectively. Lower incisors were analyzed by X-ray microtomography, it was measured the electron density of lingual and buccal enamel, and the enamel and dentin thickness. Differences in Ca and P content and electron density among the groups were analyzed by one-way ANOVA. There was no significant difference on enamel electron density and thickness among the groups (p > 0.05). However, in incisors, the higher dose of amoxicillin decreased markedly the electron density in some rats. There were no statistically significant differences in Ca (p = 0.180) or P content (p = 0.054), although the higher dose of amoxicillin could affect the enamel in some animals. The amoxicillin did not significantly alter the enamel mineralization and thickness in rats.

Association of taste receptor gene polymorphisms with dental caries

Abstract This study was performed to evaluate the interplay between dental caries, nutritional status, and genetic polymorphisms in TAS1R1 and TAS1R2 (taste receptor, type 1, member 1 and 2) in preschool children and pre-adolescents. We included 525 subjects (306 preschool children and 219 pre-adolescents). Parents/caregivers answered a self-administered questionnaire about their children's systemic health, characteristics, oral hygiene habits, and diet. Clinical examination was performed to evaluate dental caries and nutritional status. Saliva samples were collected for DNA extraction. The genotyping of rs17492553 ( TAS1R1 ), rs3935570, and rs4920566 ( TAS1R2 ) polymorphisms was performed using real-time PCR with Taqman Genotyping Master Mix and SNP assay. Both univariate and multivariate Poisson regression analyses with robust variance were used for the data analysis. In preschool children, consumption of sweets between meals increased the prevalence of dental caries by 85% (PR c = 1.85; 95%CI 1.39-2.46; p < 0.001), whereas in pre-adolescents, this prevalence increased by 34% (PR a = 1.34; 95%CI 1.11-1.62; p = 0.002), regardless of genetic polymorphisms . Moreover, individuals carrying at least one allele C in rs17492553 presented 23% more prevalence of dental caries (PR a = 1.23; 95%CI 1.02-1.49 p = 0.030). Nutritional status was not associated with dental caries, neither with genetic polymorphisms . Consumption of sweets between meals increased the prevalence of dental caries. In pre-adolescents, rs17492553 genetic polymorphism in TAS1R1 was associated with dental caries.