Antibacterial Properties In Vitro of Magnesium Oxide Nanoparticles for Dental Applications.

(1) Dental caries, periodontitis, or peri-implantitis are commensal infections related to oral biofilm former bacteria. Likewise, magnesium oxide nanoparticles (MgO-NPs) were studied to introduce them to the antibacterial properties of a few microorganisms. Considering this, the purpose of the present investigation was to determine the antibacterial properties of MgO-NPs on representative oral strains. (2) Methods: MgO-NPs with a cubic crystal structure were obtained by magnesium hydroxide mechanical activation. After synthesis, the MgO-NPs product was annealed at 800 °C (2 h). The MgO-NPs obtained were tested against ten oral ATCC strains at ten serial concentrations (1:1 20.0-0.039 mg/mL per triplicate) using the micro-broth dilution method to determine the minimal inhibitory concentration (MIC) or minimal bactericidal concentration (MIB). Measures of OD595 were compared against each positive control with a Student's t-test. Viability was corroborated by colony-forming units. (3) Results: The polycrystalline structure had an average size of 21 nm as determined by X-ray diffraction and transmission electron microscopy (high resolution). Antimicrobial sensitivity was observed in Capnocytophaga gingivalis (MIB/MIC 10-5 mg/mL), Eikenella corrodens (MIB 10 mg/mL), and Streptococcus sanguinis (MIB 20 mg/mL) at high concentrations of the MgO-NPs and at lower concentrations of the MgO-NPs in Actinomyces israelii (MIB 0.039 mg/mL), Fusobacterium nucleatum subsp. nucleatum (MIB/MIC 5-2.5 mg/mL), Porphyromonas gingivalis (MIB 20 mg/mL/MIC 2.5 mg/mL), Prevotella intermedia (MIB 0.625 mg/mL), Staphylococcus aureus (MIC 2.5 mg/mL), Streptococcus mutans (MIB 20 mg/mL/MIC 0.321 mg/mL), and Streptococcus sobrinus (MIB/MIC 5-2.5 mg/mL). (4) Conclusions: The MgO-NPs' reported antibacterial properties in all oral biofilm strains were evaluated for potential use in dental applications.

Probiotic Monotherapy with Lactobacillus reuteri (Prodentis) as a Coadjutant to Reduce Subgingival Dysbiosis in a Patient with Periodontitis.

(1) Background: Probiotics can be considered a non-invasive periodontal monotherapy for the modulation of microbiota when periodontal treatment is not accessible. The aim was to evaluate the ability of Lactobacillus reuteri Prodentis as monotherapy to modulate periodontal parameters and subgingival biofilm dysbiosis. (2) Methods: A 30-year-old patient with periodontitis was followed longitudinally after one month of daily consumption of L. reuteri Prodentis (T0). Periodontal measurements and microbial identification by Checkerboard DNA−DNA hybridization of 40 bacteria were compared between baseline (T0) and 30 days (T1) or 90 days (T2), using the Kruskal−Wallis (KW) and Mann−Whitney U (MW) tests. (3) Results: Low values of pocket depth, attachment level, dental plaque, gingival erythema (GE), and suppuration were observed at T0 vs. T1, with the clinical improvement of GE (p < 0.05, MW) and the recovery of tooth 46 fistulation. T1 vs. T0 comparisons showed lower levels (Lev) or proportions (Prop) of Parvimonas micra (Lev: p < 0.05, MW; Prop: p < 0.01, MW) and Streptococcus gordonii (Prop: p < 0.05, MW), and a predominance (Lev/Prop) of Actinomyces odontolyticus and Streptococcus mitis; lower levels and proportions of P. micra, Eubacterium saburreum, Porphyromonas gingivalis, and Tannerella forsythia were observed in tooth 46 (T1/T2 vs. T0). (4) Conclusions: Under monotherapy with L. reuteri Prodentis, periodontal measurements of the patient were maintained, with selective changes in the subgingival microbiota that were proportional to the time of probiotic administration, with any additional periodontal treatment.

Antagonist effect of probiotic bifidobacteria on biofilms of pathogens associated with periodontal disease.

The in vitro antagonist growth effect of bifidobacteria were evaluated on periodontal bacteria. Bifidobacterium longum, Bifidobacterium lactis and Bifidobacterium infantis biofilms were grown in single, double or triple combinations with putative periodontal pathogens P. gingivalis and F. nucleatum or beneficial bacteria S. oralis for 24, 72 and 168 h and the total counts were analyzed by checkerboard DNA-DNA hybridization. The results showed that B. infantis and B. lactis, as single species, demonstrated the best antagonist effect on F. nucleatum and P. gingivalis and no influence on S. oralis growth at 168 h. All the double combinations of bifidobacteria tested demonstrated an inhibitory effect on F. nucleatum (72 h) and P. gingivalis (168 h) and did not affect S. oralis counts at any time. In conclusion, B. lactis and B. infantis alone or in double combinations have antagonist effect on periodontopathogens biofilms, at different time points, and minimal influence on S. oralis growth.

Subgingival Microbiota of Mexicans with Type 2 Diabetes with Different Periodontal and Metabolic Conditions.

BACKGROUND: Type-2-Diabetes (T2D) and Periodontitis are major inflammatory diseases. However, not much is known about the specific subgingival microbiota in Mexicans with diabetes and metabolic dysbiosis. The aim of this study was to describe the subgingival microbiota of Mexicans with T2D and the different periodontal and metabolic conditions, through "Checkerboard" DNA-DNA hybridization. METHODS: Subjects were divided into two groups-periodontal-health (PH) (PH_non-T2D; n = 59, PH_T2D; n = 14) and generalized-periodontitis (GP) (GP_non-T2D; n = 67, GP_T2D; n = 38). Obesity (BMI ≥ 30 kg/m2) and serum levels of glycated-hemoglobin (HbA1c), total-lipids, triglycerides, total-cholesterol, high-density-lipids, and low-density-lipids were measured for the T2D individuals. Subgingival microbial identification was processed for 40 species through DNA-probes. RESULTS: Subjects with T2D harbored significantly higher mean total levels (PH: p < 0.001, and GP_NS), a lower proportion of "red" complex (GP: p < 0.01), a higher proportion of "yellow" (GP; p < 0.001), and "orange" (GP; p < 0.01) complex than the non-T2D. GP_T2D individuals exhibited a greater proportion of putative-species-Campylobacter gracilis and S. constellatus (p < 0.001), and Parvimonas micra and Prevotella nigrescens (p < 0.01), than GP_non-T2D. T2D individuals with HbA1c > 8% had presented significantly higher mean pocket-depth and higher levels of G. morbillorum (p < 0.05) and those with obesity or dyslipidemia harbored higher levels, prevalence, or proportion of Streptococcus sp., Actinomyces sp., and Capnocytophaga sp. CONCLUSIONS: T2D individuals harbored a particular microbial profile different to non-T2D microbiota. Metabolic control was related to dysbiosis of microbiota-HbA1c>8% related to periodontitis and obesity or dyslipidemia with the predominance of saccharolytic bacteria, irrespective of their periodontal condition.

Subgingival microbiota of periodontally untreated Mexican subjects with generalized aggressive periodontitis.

BACKGROUND AND AIM: Specific microbial profiles that may distinguish between generalized aggressive-periodontitis (GAgP) and generalized chronic-periodontitis (GCP) have, to date, not been described. The purpose of the present study was to describe the subgingival microbial composition of Mexican subjects with GAgP and compare it with that of individuals with GCP and periodontal health (PH). MATERIAL AND METHODS: Seventy-seven subjects with GAgP (n=19), GCP (n=39) and PH (n=19) were selected. Clinical measurements included plaque accumulation, gingival erythema, bleeding on probing, suppuration, pocket depth and attachment level. Up to 28 subgingival plaque samples were obtained from each subject and analysed using the checkerboard DNA-DNA hybridization technique. RESULTS: GAgP and GCP subjects harboured significantly higher levels and/or proportion of Porphyromonas gingivalis, Tannerella forsythia (levels: p<0.001, proportion: p<0.01), Prevotella nigrescens (p<0.05 levels) and "red" complex species (p<0.001 proportion) than PH subjects. All GAgP subjects were carriers of P. gingivalis and P. nigrescens. No significant differences in any of the 40 microbial species tested were detected between GAgP and GCP subjects. CONCLUSIONS: Our results revealed that the microbial differences between GAgP and GCP subjects were only discrete and none of the bacterial species tested seemed to specifically differentiate the subgingival microbial profile of either periodontitis group.

Proportion of antibiotic resistance in subgingival plaque samples from Mexican subjects.

AIM: To determine the proportion of bacteria resistant to amoxicillin and doxycycline in subgingival plaque samples from Mexican subjects. MATERIALS AND METHODS: Two subgingival plaque samples were taken from 20 Mexican subjects. Samples were dispersed, diluted and plated on non-antibiotic agar plates and on plates containing 0.5, 1, 2, 4, 8 and 16 microg/ml of either amoxicillin or doxycycline. The proportion of resistant bacteria was calculated based on the total number of colony-forming units present in the non-antibiotic containing plates. RESULTS: On average, 0.4-13.4% and 0.9-20.4% of the total cultivable subgingival microbiota was resistant to the concentrations tested of amoxicillin and doxycycline, respectively. The differences between antibiotics were statistically significant for the 0.5, 2 and 4 mug/ml concentrations (p < 0.05, Wilcoxon's test). CONCLUSIONS: Our findings revealed that a relatively small proportion of the total cultivable subgingival microbiota from Mexican subjects was resistant to amoxicillin and doxycycline.

Description of the subgingival microbiota of periodontally untreated Mexican subjects: chronic periodontitis and periodontal health.

BACKGROUND: Recent studies have suggested that changes in the prevalence and/or proportion of distinct microorganisms characterize the subgingival microbial profiles of populations around the world. At present, no information is available on the subgingival microbiota of Mexican subjects. The purpose of the present study was to determine the microbial composition of subgingival plaque in Mexican subjects with untreated chronic periodontitis. METHODS: A total of 44 chronic periodontitis and 20 periodontally healthy subjects (who were currently non-smokers) were selected. Clinical measurements including plaque accumulation, gingival erythema, bleeding on probing, suppuration, probing depth, and attachment level were recorded at six sites of every tooth. Up to 28 subgingival plaque samples were obtained from each subject and individually analyzed to determine the levels, proportion, and prevalence of 40 microbial species using the checkerboard DNA-DNA hybridization technique. RESULTS: Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythensis were the only species that presented higher mean levels in periodontitis subjects. The proportions of P. gingivalis (P<0.001), T. forsythensis (P<0.01), and red complex species (P. gingivalis, T. forsythensis, and T. denticola; P<0.001) as a group were also significantly higher in periodontitis subjects. Periodontally healthy subjects harbored a significantly larger proportion of Actinomyces species (P<0.05). No significant differences were detected in the percentage of carriers of any of the species tested. CONCLUSIONS: Our results revealed that the subgingival microbiota of untreated chronic periodontitis Mexican subjects was characterized by increases in the level, prevalence, and proportion of classic periodontal pathogens. However, the prevalence and proportion of specific microbial species varied significantly from the results of other reports on subjects from different geographical locations.

Distribution of selected bacterial species on intraoral surfaces.

BACKGROUND/AIM: To examine the proportions of 40 bacterial species in samples from 8 oral soft tissue surfaces and saliva in systemically healthy adult subjects and to compare these microbiotas with those of supra- and subgingival plaque. METHODS: Microbial samples were taken from 8 oral soft tissue surfaces of 225 systemically healthy subjects using a "buccal brush". Saliva was taken by expectoration. Forty-four of these subjects provided additional supra- and subgingival plaque samples. Samples were individually evaluated for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The percentage of total DNA probe count was determined for each species, at each sample location and averaged across subjects. The significance of differences among the proportions of the 40 test species at different sample locations was sought in the 225 and 44 subjects separately using the Quade test and adjusted for multiple comparisons. Cluster analysis was performed using the proportions of the 40 species at the different sample locations using the minimum similarity coefficient and an average unweighted linkage sort. The proportions of each species were averaged across subjects in the resulting cluster groups and the significance of differences was tested using the t-test and ANOVA. RESULTS: Microbial profiles differed markedly among sample locations in the 225 subjects, with 34 of 40 species differing significantly. Proportions of Veillonella parvula and Prevotella melaninogenica were higher in saliva and on the lateral and dorsal surfaces of the tongue, while Streptococcus mitis and S. oralis were in significantly lower proportions in saliva and on the tongue dorsum. Cluster analysis resulted in the formation of 2 clusters with >85% similarity. Cluster 1 comprised saliva, lateral and dorsal tongue surfaces, while Cluster 2 comprised the remaining soft tissue locations. V. parvula, P. melaninogenica, Eikenella corrodens, Neisseria mucosa, Actinomyces odontolyticus, Fusobacterium periodonticum, F. nucleatum ss vincentii and Porphyromonas gingivalis were in significantly higher proportions in Cluster 1 and S. mitis, S. oralis and S. noxia were significantly higher in Cluster 2. These findings were confirmed using data from the 44 subjects providing plaque samples. The microbial profiles of supra- and subgingival plaque differed from the other sample locations, particularly in the increased proportions of the Actinomyces species. Species of different genera exhibited different proportions on the various intraoral surfaces, but even within the genus Streptococcus, there were differences in colonization patterns. S. oralis, S. mitis and S. constellatus colonized the soft tissues and saliva in higher proportions than the samples from the teeth, while the other 4 streptococcal species examined colonized the dental surfaces in proportions comparable to the soft tissue locations and saliva. CONCLUSIONS: Proportions of bacterial species differed markedly on different intraoral surfaces. The microbiota of saliva was most similar to that of the dorsal and lateral surfaces of the tongue. The microbiotas of the soft tissues resembled each other more than the microbiotas that colonized the teeth both above and below the gingival margin.