Anti-Adherence and Antimicrobial Activities of Silver Nanoparticles against Serotypes C and K of Streptococcus mutans on Orthodontic Appliances.

Background and Objectives: Streptococcus mutans (S. mutans) is the main microorganism associated with the presence of dental caries and specific serotypes of this bacteria have been related to several systemic diseases limiting general health. In orthodontics, white spot lesions (WSL), represent a great challenge for clinicians due to the great fluctuation of their prevalence and incidence during conventional orthodontic treatments. Although silver nanoparticles (AgNP) have been demonstrated to have great antimicrobial properties in several microorganisms, including S. mutans bacteria, there is no available information about anti adherence and antimicrobial properties of AgNP exposed to two of the most relevant serotypes of S. mutans adhered on orthodontic materials used for conventional therapeutics. The objective of this study was to determine anti-adherence and antimicrobial levels of AgNP against serotypes c and k of S. mutans on conventional orthodontic appliances. Materials and Methods: An AgNP solution was prepared and characterized using dispersion light scattering (DLS) and transmission electron microscopy (TEM). Antimicrobial and anti-adherence activities of AgNP were determined using minimal inhibitory concentrations (MIC) and bacterial adherence testing against serotypes c and k of S. mutans clinically isolated and confirmed by PCR assay. Results: The prepared AgNP had spherical shapes with a good size distribution (29.3 ± 0.7 nm) with negative and well-defined electrical charges (−36.5 ± 5.7 mV). AgNP had good bacterial growth (55.7 ± 19.3 µg/mL for serotype c, and 111.4 ± 38.6 µg/mL for serotype k) and adherence inhibitions for all bacterial strains and orthodontic wires (p < 0.05). The serotype k showed statistically the highest microbial adherence (p < 0.05). The SS wires promoted more bacterial adhesion (149.0 ± 253.6 UFC/mL × 104) than CuNiTi (3.3 ± 6.0 UFC/mL × 104) and NiTi (101.1 ± 108.5 UFC/mL × 104) arches. SEM analysis suggests CuNiTi wires demonstrated better topographical conditions for bacterial adherence while AFM evaluation determined cell wall irregularities in bacterial cells exposed to AgNP. Conclusions: This study suggests the widespread use of AgNP as a potential anti-adherent and antimicrobial agent for the prevention of WSL during conventional orthodontic therapies and, collaterally, other systemic diseases.

Determination and identification of antibiotic-resistant oral streptococci isolated from active dental infections in adults.

OBJECTIVE: To determine and identify antibiotic-resistant bacteria (ARB) of oral streptococci from active dental infections in adults and its association with age and gender. MATERIAL AND METHODS: This cross-sectional study included 59 subjects from 18 to 62 years old. Ninety-eighth samples obtained from the subjects were cultivated in agar plates containing antibiotics amoxicillin/clavulanic acid (A-CA), clindamycin, and moxifloxacin (concentrations of 16, 32 or 64 µg/ml). PCR assay was performed to identify bacterial species. RESULTS: The bacterial species that showed more antibiotic-resistance (AR) was S. mutans (45.9%), followed by S. gordonii (21.6%), S. oralis (17.6%), S. sanguinis (9.5%), S. salivarius (5.4%) and S. sobrinus (0%). Moreover, clindamycin (59.4%) showed the highest frequency of AR. Moxifloxacin and A-CA showed an susceptibility >99.1%, while clindamycin showed the lowest efficacy (93.3%); there was a significant statistically difference (p < .01). The age group between 26 and 50 years old (32.2%) and females (28.8%) showed more multiresistance. Clindamycin showed a statistical difference (p < .05) when comparing groups by gender. CONCLUSIONS: Clindamycin was the antibiotic with the highest frequency of ARB and lower bactericidal effect. Moxifloxacin and A-CA showed the highest efficacy and the lowest ARB frequency. Streptococcus mutans was the bacterial specie that showed an increased frequency of AR.

Association of cytokines polymorphisms with chronic peridontitis and rheumatoid arthritis in a Mexican population.

OBJECTIVE: Historically, it has been shown that rheumatoid arthritis (RA) and periodontitis (PE) share pathophysiological similarities and possibly a genetic background. In order to elucidate the genetic background between both diseases, we evaluated the distributions of five SNPs genotypes and all the possible haplotypes composed in subjects with isolated RA, PE, combined diseases and healthy controls. MATERIALS AND METHODS: The study population consisted of 280 Mexican subjects. Genomic DNA was isolated from buccal epithelial cells collected by cheek scrapings and analyzed for the determination of the following SNPs: IL-1α + 4845 (rs17561), IL-1α -889 (rs1800587), IL-1ß + 3954 (rs1143634), IL-1ß -511(rs16944) and TNF-α -308 (rs1800629). RESULTS: After adjustment for age, sex and smoking status, multiple logistic regression analysis revealed a no significant association in the genotype frequencies of TNF-α -308 and IL-1α + 4845 SNPs. Otherwise a significant association was observed in IL-1ß + 3954 and IL-1ß -511 (p < 0.05) while IL-1α -889 was of borderline statistical significance (p = 0.054). Also, we found three negative associated haplotypes with PE: IL-1α + 4845 G/IL-1ß -511 A, IL-1ß + 3954 C/IL-1ß -511 A and interestingly IL-1α -889 C/IL-1ß -511 A also with a positive association with RA. CONCLUSIONS: Some genotypes and haplotypes are associated with the diseases. But it seems that the genetic background of the association between RA and PE needs to be explored deeper.

Association between periodontitis, periodontopathogens and preterm birth: is it real?

PURPOSE: To identify the association between periodontitis and periodontal pathogens with preterm birth despite the strict control of some important confounders, such as infectious processes and criteria for diagnosis of periodontitis during pregnancy. MATERIALS AND METHODS: In this cross-sectional study were included 70 healthy puerperal women between 20 and 35 years without a history of genitourinary infections during pregnancy. Based on the gestational age they were divided into two groups: 45 with term birth (>37 weeks) and 25 with preterm birth (<37 weeks). Previous informed consent, a gynecologic and dental history that included gynecologic and obstetric background, periodontal status applying different authors' criteria of periodontitis diagnosis, presence of periodontopathogens, dental caries and oral hygiene were recorded. RESULTS: There was no association between periodontitis, periodontopathogens and preterm birth. There were no statistical differences applying different authors' criteria diagnosis of periodontitis. Gingivitis status was similar, but probing depth was greater in preterm birth subjects, perhaps they are young women, and this finding could be an early sign of periodontitis. In like manner, the main periodontal bacterial species are not associated with preterm birth, general hygiene and care habits are poorer than term birth subjects. CONCLUSION: We could suggest that preterm birth is a multifactorial condition and the role of periodontitis and the periodontopathogens itself is not sufficient to trigger the preterm birth. There are factors such as infectious processes and diagnostic criteria for periodontitis that could be responsible for controversial results.

[Evaluation of dental treatment impact in a northwestern Mexican school children population]. / Evaluación del impacto del tratamiento odontológico en una población escolar del noroeste de México.

OBJECTIVE: To evaluate through functional teeth index, the impact in schoolchildren in communities with and without dental community support. MATERIAL AND METHODS: A cross-sectional study was carried out in communities with dental care provided by dental clinics of Sinaloa State University. The study sample was 2,083 schoolchildren. We used the criteria proposed by WHO for the index of decayed, missing-teeth (DMFT) for permanent dentition, index for prima- ry teeth (dmft) and the rate of functional teeth (RFT). For bivariate analysis, the nonparametric tests Pearson f and Mann-Whitney U were used. RESULTS: The comparisons of DMFT (0.20) and RFT (13.95) of children with and DMFT (0.43) and RFT (14.82) of children without community dental support showed statistical significant difference (p < 0.05). There was a statistically significant difference in DMFT and RFT between samples with and without community dental support (p < 0.05). The age showed a statistically significant difference between the DMFT and dmft (p < 0.05). Primary dentition required more dental care than permanent dentition. There was access for dental treatment, but it is not used for the population. CONCLUSIONS: The RFT provided precise information than DMFT, mainly due to register the changes of actions focused to recover the teeth function in the oral cavity.

[Predicting risk of caries in schoolchildren from northwestern Mexico: longitudinal study]. / Predicción de riesgo de caries en escolares del noroeste de México: estudio longitudinal.

OBJECTIVE: To analyze the caries risk through the Bratthall's Cariogram (BC) and the frequency of dental caries in a Mexican northwest children population for 12 months period. MATERIAL AND METHODS: A cohort of 583 scholar children between 6 and 10 years old from Sinaloa state was involved for 12 months period (2007-2008). The Bratthall's Cariogram was used to predict caries risk and the. WHO's criteria were used to obtain the caries index. The caries risk association with clinical variables was analyzed by logistic regression analysis and Sperman's Rho rank correlation test was used to evaluate the correlation between DMFT index and BC. RESULTS: The caries risk increased with respect to age (p < 0.05), the CB identified correctly children for high risk (85%) and low risk (65%) caries for a 12 months period. The baseline values of BC showed a positive correlation with DMFT index (0.86 and p = 0.0001); the diagnostic test evaluation showed the following values: positive predictive value of 87%, negative predictive value of 63%, sensitivity of 93% and specificity of 63%. CONCLUSIONS: The caries risk increased with the age in the studied population. The Bratthall's Cariogram is a useful screening test to evaluate the risk for dental caries at individual and population levels.

Clinical evaluation of the accuracy of conventional radiography and apex locators in primary teeth.

PURPOSE: The purpose of this study was to clinically evaluate the accuracy of conventional radiography and 2 apex locators (Root ZX and ProPex) in determining the working length of root canals in primary teeth and to compare the results with scanning electron microscopy (SEM). METHODS: A general medical and oral history was obtained from 1,600 children and 50 children were selected. The working lengths of the primary teeth root canals were determined with conventional radiography and 2 apex locators (Root ZX and ProPex). These results were compared with the ideal standard using SEM. To determine the difference among means of the different methods, the Wilcoxon test was applied. To determine the accuracy of the methods with the ideal standard (SEM), the Lin interclass correlation coefficient (ICC) was used. RESULTS: Sixty-one canals were evaluated and there were no significant difference in the 3 techniques in accuracy of determination of the working length of the canals. The most accurate method of determining the working length of the root canals in primary teeth was the Root ZX (ICC=0.72), followed by the ProPex (ICC=0.70), and the least accurate was conventional radiography (ICC=0.67). CONCLUSION: The apex locators were more accurate than conventional radiography in determining the working length.

Association between caries, obesity and insulin resistance in Mexican adolescents.

AIM: To determine the association among dental caries, obesity and insulin resistance in Mexican adolescents. METHODS: Body mass index, obesity (OB) blood pressure, insulin level, insulin resistance (IR), triglycerides level, serum HDL-cholesterol (cHDL), DMFT index and salivary flow were measured. RESULTS: Anthropometric measures showed a significant statistical difference (p < 0.05). Insulin level was 8.98 for healthy subjects, whereas for OB-IR group was 25.35, there was a statistical significant difference (p < 0.05). Triglycerides level was 88.50 for healthy subjects and 169.40 mg/dL for OB-IR; cHDL was 52.88 for healthy and 41.82 mg/dL for OB-IR group, both showed a statistically significant difference (p < 0.05). Salivary flow was 4.30 for healthy and for OB-IR group was 5.48 ml/min showed a significant statistical difference (p < 0.05). DMFT index was 3.02 for healthy and for OB-IR adolescents was 4.78, showed a significant statistical diference (p < 0.05). The caries component of DMFT index was 1.84 for healthy and was 3.52 for OB-IR adolescents, showed a significant statistical difference (p < 0.05). According to the multivariate analysis, DMFT (OR = 3.10; IC 95% = 0.20-1.02, p = 0.042) and decay (OR = 3.30; IC 95% = 0.19-1.0, p = 0.011) were associated with subjects with OB-IR. CONCLUSION: OB-IR Mexican adolescents showed a positive association with DMFT.

Corrigendum to "In Vitro Determination of Genotoxicity Induced by Brackets Alloys in Cultures of Human Gingival Fibroblasts".

[This corrects the article DOI: 10.1155/2020/1467456.].

Atomic force microscopy observation of the enamel roughness and depth profile after phosphoric acid etching.

The aim was to compare the enamel surface roughness (ESR) and absolute depth profile (ADP) (mean peak-to-valley height) by atomic force microscopy (AFM) before and after using four different phosphoric acids. A total of 160 enamel samples from 40 upper premolars were prepared. The inclusion criterion was that the teeth have healthy enamel. Exclusion criteria included any of the following conditions: facial restorations, caries lesions, enamel hypoplasia and dental fluorosis. Evaluations of the ESR and ADP were carried out by AFM. The Mann-Whitney U-test was used to compare continuous variables and the Wilcoxon test was used to analyze the differences between before and after etching. There were statistically significant differences (P

[Epidemiologic study on dental caries and treatment needs in schoolchildren aged six to twelve years from San Luis Potosi]. / Estudio epidemiológico sobre caries dental y necesidades de tratamiento en escolares de 6 a 12 años de edad de San Luis Potosí.

OBJECTIVE: To determine the experience, prevalence and severity of dental caries, as well as the Significant Caries Index (SiC) and the treatment needs (TN) in schoolchildren aged six to twelve years. Equally, to estimate the effect of caries in primary dentition on caries in permanent dentition. MATERIAL AND METHODS: A cross-sectional study was realized in 3865 schoolchildren from San Luis Potosí City, Mexico. Subjects were clinically evaluated by three standardized examiners (kappa > 0.85). For detection of caries was employed the WHO's criteria for primary (dmft) and permanent (DMFT) dentitions. In the statistical analyzes non-parametric test and logistic regression were used. RESULTS: Mean of age was 8.69 +/- 1.79 and 51.3% were women. In the primary dentition: dmft index was 1.88 +/- 2.34 and the caries prevalence (dmft >0) of 56.8%. In account to severity 22.0% and 5.6% have dmft >3 and dmft >6, respectively. In children of six years, the caries prevalence was 56.0% and the SiC of 5.45. In the permanent dentition: DMFT index was 1.11 +/- 2.03 and the caries prevalence (DMFT >0) of 36.8%. In account to severity 11.8% and 2.8% have DMFT >3 and DMFT >6, respectively. In children of twelve years, the DMFT index caries 4.14 +/- 4.15 and the SiC of 9.15. The TN index was of 88.5% for primary dentition and 93.6% for the permanent. In logistic regression we observed associated to caries prevalence in permanent dentition; presence of caries in primary dentition (OR = 6.37; p < 0.001), female sex (OR = 1.33; p < 0.001) and higher age (OR = 1.69; p < 0.001). CONCLUSIONS: Caries prevalence to six years old and DMFT index to twelve years old were highest to values established by WHO. Caries severity in the primary dentition was two times than observed in the permanent dentition. High TN in both dentitions was observed. Presence of caries in primary dentition was a strong risk indicator for to present caries in permanent dentition.

Dental plaque microbiota of pet owners and their dogs as a shared source and reservoir of antimicrobial resistance genes.

OBJECTIVE: This investigation aimed to detect coincidences in the antimicrobial resistance genes (ARG) profiles between members of a group living in a household and to compare them between other groups in order to establish if an exchange of ARG occurs and if dental plaque microbiota can be considered as a source and reservoir of ARG that can be shared between humans and pets. METHODS: One hundred sixty dental plaque samples were obtained from four groups: Shelter dogs group (n=20), adult pet owners and dogs group (AD group, n=40), adult pet owners, children and dogs group (ACD group, n=60), and adult non-pet owners and children group (AC group, n=40). DNA was obtained, and specific primers with polymerase chain reaction for ARG detection were used. RESULTS: The AD group exhibited the most coincidences in their ARG profiles, 14 (70%) of the 20 profiles coincided in 100% followed by the ACD group with 9 (45%) coincidences. While the AC group was the less coincident group, only 7 (35%) of the 20 profiles coincided. tetM was the most prevalent with 53.1%, followed by tetQ with 52.5% and cfxA with 51.2%, while the less prevalent were tetW with 31.8%, blaTEM-1 with 27.5%, and ermC with 18.7%. CONCLUSION: Dental plaque microbiota can be considered as a source and reservoir of ARG that can be shared between humans and dogs living in a household. The dogs seem to play an important role in the transference of ARG, and the children appear to be the most affected by carrying the most significant number of ARG.

In Vitro Determination of Genotoxicity Induced by Brackets Alloys in Cultures of Human Gingival Fibroblasts.

Orthodontic brackets release ions that can be reabsorbed in the oral mucosa, potentially causing complications, including cytotoxic effects and mutagenic alterations. The aim was to evaluate the genotoxicity induced by orthodontic appliance alloys in cultures of human gingival fibroblasts by comet assay. Eluates were obtained from the following brackets alloys: EconoLine (SS: stainless steel), MiniMirage (Ni-Ti: nickel-titanium), Nu-Edge (Co-Cr: cobalt-chromium), In-Vu (PC-polycrystals (PC) aluminum oxide), and Monocrystal IZE (monocrystalline (MC) aluminum oxide). Each bracket was sterilized and exposed to a corrosive process for 35 days. The obtained eluates were tested for genotoxicity of human gingival fibroblasts (HGFA) by the alkaline comet assay. All study groups showed genotoxic effects; there was a significant difference (p < 0.0001) among groups. The eluates obtained from Ni-Ti showed a 16-times greater genotoxic effect. There were differences in genotoxicity after comparing the Ni-Ti with SS (p < 0.01) and Co-Cr brackets (p < 0.001). The ceramic was more genotoxic than metallic brackets (SS and Co-Cr), but less than the Ni-Ti. This in vitro model will be useful for further study of early DNA damage caused by brackets and other biomaterials used in the oral cavity before their introduction into the clinical setting.

Detection of periodontal bacterial DNA in serum and synovial fluid in refractory rheumatoid arthritis patients.

AIM: To identify periodontal bacterial DNA (PBDNA) by PCR in subgingival dental plaque (SDP), serum and synovial fluid (SF) of rheumatoid arthritis (RA) with periodontal disease (PD) patients and to explore the possible PBDNA transport pathways from mouth to joints. METHODS: This cross-sectional prolective study involved 19 subjects with RA and PD. Informed consent, health and dental questionnaires were obtained. SDP, SF and serum samples were obtained, and leucocytes were isolated from blood. DNA was extracted and PCR assays to detect main PD species were carried out. Cultures on agar plates and broth, from each sample, were performed. RESULTS: Hundred percentage of patients showed PBDNA in SDP and SF and 83.5% in serum. Prevotella intermedia (89.4% and 73.6%) and Porphyromonas gingivalis (57.8% and 42.1%) were the species most frequently detected in SDP and SF, respectively. In SDP, 4.05 different bacterial species were found followed by 1.19 in serum and 2.26 in SF. Culture onto agar plates and broth did not show any bacterial growth, leucocytes were not positive to PBDNA by PCR. CONCLUSION: This study suggests that PBDNA could have a role on the RA aetiology. The possible pathway of transport of PBDNA from mouth to joints could be via the free form of DNA.

Dental treatment under general anesthesia in healthy and medically compromised developmentally disabled children: a comparative study.

AIM: To compare the type, number of procedures and working time of dental treatment provided under dental general anesthesia (DGA) in healthy and medically compromised/developmentally disabled children (MCDD children). DESIGN: This cross-sectional prospective study involved 80 children divided into two groups of 40 children each. Group 1 consisted of healthy and Group 2 consisted of MCDD children. RESULTS: Healthy children needed more working time than MCDD children, the means being 161 +/- 7.9 and 84 +/- 5.7 minutes, respectively (P = 0.0001). Operative dentistry and endodontic treatments showed a significant statistical difference (P = 0.0001). The means of procedures were 17 +/- 5.0 for healthy children and 11 +/- 4.8 for MCDD children (P = 0.0001). CONCLUSIONS: Healthy children needed more extensive dental treatment than MCDD children under DGA. The information from this sample of Mexican children could be used as reference for determining trends both within a facility as well as in comparing facilities in cross-population studies.

Prevention of infective endocarditis and bacterial resistance to antibiotics: A brief review.

The purpose of this statement is to debate the recommendations of the American Heart Association (AHA) for the prevention of infective endocarditis through an antibiotic prophylaxis protocol and its relation with bacterial resistance to antibiotics. Since dental infections involve biofilms that include several bacterial species (Gram-negative and Gram-positive), it is essential, from the dental point of view, to consider the frequency, magnitude, and duration of bacteremia associated with active dental infections before applying antibiotic prophylaxis. The actual guidelines for antibiotic prophylaxis should be revised according to recent evidence of bacterial resistance. Amoxicillin/clavulanic acid and moxifloxacin should be considered due to their effectiveness against bacteria associated with oral, GU, and GI infections and the low rates of antibiotic resistance associated with these antibiotics, instead of the actual protocol, which includes amoxicillin (2 g) or clindamycin (600 mg) administered an hour before the dental procedures. The breaking point to test the antibiotic bacterial resistance (ABR) had a wide range in the different studies that were analyzed, which could explain the widely varied ABR percentages reported for the various antibiotics used for antibiotic prophylaxis.

In vitro retention efficiency of temporary type zinc oxide cement for orthodontic forced eruption.

OBJECTIVE: To assess the retention efficiency of three types of temporary zinc oxide cement trademarks on forced eruption using intracranal wire device. METHODS: An in vitro evaluation included intracanal wire device displacement and detachment at 50g load force for 120 days and then the retention resistance at maximum load force. RESULTS: All groups of temporary zinc oxide cements were efficient to support 50g load forces after 120 days. None statistical differences were found between groups. Zinc oxide cements supported a maximum retention load force, which exceeded in more than 84 times the lowest value obtained in controls (420g). CONCLUSION: Zinc oxide cements are efficient to retain intracanal wire devices on forced eruption processes in vitro and allows removal of both when necessary (wire device and cement, respectively).

Antimicrobial activity of endodontic sealers and medications containing chitosan and silver nanoparticles against Enterococcus faecalis.

BACKGROUND: The main microorganism associated with the failure of endodontic treatments is Enterococcus faecalis. Although several endodontic therapeutics have demonstrated antimicrobial activity against E. faecalis, the antimicrobial effectiveness of chitosan (CsNPs) and silver nanoparticles (AgNPs) included into conventional endodontic sealers for endodontic therapies is still unclear. AIM: The objective of this study was to evaluate the antibacterial activity increment (AAI) of endodontic sealers containing CsNPs and AgNPs as well as some chemical components against E. faecalis by direct contact assays. METHODS: CsNPs and AgNPs were synthesized by reduction and ionic gelation methods, respectively. Nanoparticles were characterized by dynamic light scattering and energy dispersive X-ray analysis. The bactericidal activity was tested on monolayers on agar plates and collagen membrane surface assays against E. faecalis. RESULTS: The size of CsNPs was 70.6±14.8 nm and zeta potential was 52.0±5.4 mV; the size of AgNPs was 54.2±8.5 nm, and zeta potential was -48.4±6.9 mV. All materials, single or combined, showed an AAI, especially when CsNPs, chlorhexidine (Chx), and the combination of CsNPs-Chx were added. However, the combination of CsNPs-Chx showed the highest (55%) AAI, followed by Chx (35.5%) and CsNPs (11.1%), respectively. There was a significant statistical difference in all comparisons (p < 0.05). Tubliseal (40%) and AH Plus (32%) sealants showed a higher AAI on E. faecalis in the monolayer test and collagen membrane assay analyzed by scanning electron microscopy. CONCLUSIONS: Tubliseal and AH plus sealers combined with nanoparticles, especially CsNPs-Chx, could be used for conventional endodontic treatments in the control of E. faecalis bacteria.

Interproximal caries and premature tooth loss in primary dentition as risk factors for loss of space in the posterior sector: A cross-sectional study.

Dental caries-a highly prevalent public health problem in preschoolers and school children-is the main cause of premature dental loss during childhood, and this may be related to loss of space in the posterior sector. The objective of this study was to evaluate whether interproximal caries and premature tooth loss (D and/or E) are risk factors for loss of space in the posterior sector.A comparative cross-sectional study (split-mouth type) was performed in schoolchildren (6-8 years old). Seventeen gypsum models were evaluated. These children presented with unilateral loss of a dental organ or interproximal caries (teeth D and/or E) and without such affectations on the other side. Measurements were made with a digital Vernier caliper. The dependent variable was the difference (loss of space, mm) between the control and case sides. The independent variables were type of affectation (interproximal caries or tooth loss), sex, age, arcade, and number of interproximal surfaces affected.The mean age was 6.82 ±â€Š0.44 years and 64.7% were boys. The average space loss was 1.09 ±â€Š0.18 mm (control vs case; P < .0001). A greater loss of space was observed among those who lost a dental organ than those with interproximal caries (P = .0119). A correlation was observed between the variable loss of space and the number of interproximal surfaces affected (r = 0.5712, P = .0166).Interproximal caries and tooth loss were risk factors for loss of space in the posterior segment in this sample of Mexican schoolchildren.

Distribution of Streptococcus mutans and Streptococcus sobrinus in saliva of Mexican preschool caries-free and caries-active children by microbial and molecular (PCR) assays.

The aim of the study was to investigate the distribution of mutans streptococci (MS) infection of caries-free (CF) and caries-active (CA) preschool Mexican children by microbial and molecular assays. Eighty preschool children were divided into two groups, 40 CF and 40 CA children. Saliva samples were inoculated onto MSB to identify CFU and DNA extractions were tested by PCR. Our results indicated that there was no statistical difference (p > 0.05) between groups either in age, weight, height or sex. S. sobrinus was detected by PCR twice as much in the CA group, the difference being statistically significant (p < 0.05). dmfs index was positive correlated with S. mutans (r = 0.2941, p = 0.0081), S. sobrinus (r = 0.3384, p = 0.0021) and S. mutans-S. sobrinus (r = 0.3978, p = 0.0003). ANCOVA revealed that dmfs index had a significant effect on the distribution of CFU of S. mutans (p = 0.0118) and S. sobrinus (p = 0.03). When MSB was compared with PCR to identify MS, there was no statistical difference (p > 0.05). We conclude that S. mutans and S. sobrinus were isolated in higher numbers from CA children and those harbouring both bacteria had higher dmfs scores. PCR is a useful tool in molecular epidemiology for dental caries studies; it was effective in detecting and identifying MS from saliva in children.