Oral Microbiota: Discovering and Facing the New Associations with Systemic Diseases

Effects of oral health intervention strategies on cognition and microbiota alterations in patients with mild Alzheimer's disease: A randomized controlled trial

We explored the effects of an oral health intervention on the oral microbiome and cognitive function of patients with mild Alzheimer's disease (AD) and determined the influence on disease progression. Sixty-six patients with mild AD were randomly assigned to intervention or control groups and received a 24-week oral health intervention and routine care, respectively. Data were collected at baseline and week 24. 16 S rRNA sequencing was used to analyze oral microbiota. After 24 weeks of oral health intervention, Kayser-Jones Brief Oral Health Status Examination (BOHSE), Mini-Mental State Examination (MMSE), Neuropsychiatric Inventory (NPI), Nursing Home Adjustment Scale (NHAS), and Alzheimer's Disease Cooperative Study-ADL (ADCS-ADL) scores were different between groups (p < 0.05). Subgingival plaque in patients with AD showed significant differences in the diversity and abundance of oral microbiomes, with a higher abundance of normal oral flora in the intervention group. We found oral health intervention strategies are effective in modifying subgingival microbiota differences and slowing cognitive decline in mild AD patients.

Prevalence of Bone Loss in Mandibular Future Abutment Teeth among Diabetic and Non-Diabetic Patients: A Retrospective Case-Control Study

Objective:

This study aimed to compare the prevalence of bone loss in lower permanent premolars and canines, which can serve as abutments for future prostheses, among diabetic and non-diabetic patients.

Materials and Methods:

In this retrospective case-control study, records of patients who visited the dental clinics of Imam Abdulrahman Bin Faisal University were used. Inclusion criteria were the presence of a complete periodontal chart, full mouth radiographs, and past medical history (presence of DM, hypertension, and/or coronary heart disease). The criteria for exclusion were the reporting of malignancy, pregnancy, breastfeeding, or taking of the medications that affect bone turnover, periodontal surgery within the past year, absence of radiographs with good quality, and antibiotic use within 3 months prior to the dental visit. Demographical data, including gender and age, past medical history (diabetic state), and periodontal diagnosis, were collected. The severity of periodontal disease, radiographic bone loss (RBL), and its pattern were also assessed.

Results:

Out of 400 records, 363 patient files were included. Of those, almost 36% were males and 64% were females. The patients’ age was ranging from 16 to 82 years. About 34% of the patients were diagnosed with generalized periodontitis while 22% had localized periodontitis. With regards to the severity of the cases, the prevalence was equally distributed between mild (37%) and moderate periodontitis (38%), while 25% were diagnosed with severe periodontitis. A total of 22% of the patients were diabetic, which showed an increase in the severity of bone loss by an average of 31% across the selected teeth (mandibular canines and premolars). The pattern of bone loss was higher in the mandibular incisors, followed by the canines and the premolars. Multiple regression models showed that non-diabetics were significantly less likely to have bone loss in all the selected teeth and the male patients had 2 times the likelihood of having bone loss. Although the mandibular canines have the highest root length in the mandible, they were the most affected by bone loss in diabetic patients with periodontitis.

Conclusion:

Results of this study suggested that mandibular premolars were the teeth least affected by bone loss in both, diabetic and non-diabetic groups. Therefore, they can be considered the most suitable teeth to be used as abutments for the future prosthesis.

Research progress on the relationship between chronic periodontitis and Parkinson's disease

Chronic periodontitis is an infectious disease, which has a reciprocal relationship with a variety of systemic disorders. Parkinson's disease is a prevalent neurodegenerative disease in which inflammation plays an important role for its progression. A vast number of studies suggest that there is a potential connection between chronic periodontitis and neurodegenerative diseases such as Parkinson's disease. Individuals with Parkinson's disease usually have poor periodontal health, and their oral flora composition differs from that of healthy people; at the same time, patients with chronic periodontitis have a higher risk of Parkinson's disease, which can be reduced with regular periodontal treatment. In fact, the mechanism of interaction between chronic periodontitis and Parkinson's disease is not clear. According to several studies, the clinical symptoms of Parkinson's disease prevent patients to maintain oral hygiene effectively, increasing the risk of periodontitis. Neuroinflammation mediated by microglia may be the key to the influence of chronic periodontitis on Parkinson's disease. Periodontal pathogens and inflammatory mediators may enter the brain and activate microglia in various ways, and ultimately leading to occurrence and development of Parkinson's disease. This article reviews the recent research progress on the association between chronic periodontitis and Parkinson's disease, and its potential mechanism to provide information for further research.

Effects of Soft Tissue Closure on Medication-Related Osteonecrosis of the Jaw in a Rabbit Model with Tooth Extraction: A Pilot Study

Objectives

The study investigated the effect of soft tissue closure after tooth extraction on the prevention of medication-related osteonecrosis of the jaw in a rabbit model.

Materials and Methods

Twenty female New Zealand white rabbits were randomly assigned into the experimental group administrated with zoledronic acid (ZA) and control groups treated with saline. Bilateral lower premolar extraction was performed 4 weeks after ZA/saline administration. Immediately after extraction, the wound on the right mandible was closed by suture while the other side was left open. Animals were sacrificed 4 weeks and 8 weeks after tooth extraction. Fluorochrome labeling solutions were injected subcutaneously to evaluate the bone growth rates. The mandibles were harvested and subjected for microcomputed tomography, confocal microscope, and histomorphological examinations.

Results

All extraction sites healed well without any signs of infection. Trabecular thickness (Tb.Th) was significantly higher in the ZA-treated group than in the control group at both week 4 and week 8, while no significant difference was detected in the rest of the assessed parameters. The bone growth rate in mandibles showed gradual reduction in the ZA-treated group. Histological analysis showed that at week 8, the animals in the ZA-treated group had significantly higher incidence of osteonecrosis than that in the control group, while no significance was revealed between the sutured and nonsutured side.

Conclusions

ZA treatment significantly reduces bone growth rates but does not reveal a significant effect on bone mineral density and bone microarchitecture. Soft tissue closure of the extraction socket does not reduce the incidence of ONJ in the ZA-treated rabbit model.

Dental Caries among Refugees in Europe: A Systematic Literature Review

Oral health is one of the most neglected aspects of refugee health. The study aimed to systematically review evidence on prevalence of dental caries and dental care services provided to refugees in Europe. Following PRISMA guidelines, we searched PubMed, Cochrane, WHOLIS, Web of Science, Medline Ovid, and Google Scholar identifying studies on dental caries among refugees in Europe after the 2015 refugee crisis. From 3160 records, fourteen studies were included in the analysis. Eight studies on oral health showed caries prevalence of between 50% and 100%, while it ranged from 3% to 65% in six general health studies. Caries prevalence was proportional to age and inversely associated with education, whereas gender and country of origin showed no significant association. Nowhere is oral health part of general health assessment on arrival and is complaint based. Primary focus on resettlement, language, cultural, and economic barriers emerged as explanatory models for limited access. Our study identified a high prevalence of caries and limited access to dental health services as main challenges. Integrating oral health check-ups may contribute in shifting towards preventive oral care. Further research is urgently needed to better understand the dental needs of refugees in Europe.

Ethanol extract of Schinus molle L. (Molle) and Erythroxylum coca Lam (Coca): Antibacterial Properties at Different Concentrations against Streptococcus mutans: An In Vitro Study

OBJECTIVE

The aim of this study was to compare in vitro the antibacterial activity of an ethanol extract of Erythroxylum coca Lam (EEE) and Schinus molle L. (EES) at 50% and 75% versus Streptococcus mutans ATCC 25175.

MATERIALS AND METHODS

This was a prospective, comparative, longitudinal experimental study. The ethanol extract of coca and molle leaves was obtained by the vacuum filtration method at concentrations of 50% and 75% and was compared with a positive control (0.12% chlorhexidine). Streptococcus mutans strains were isolated in a culture medium (Mitis Salivarius Agar) ideal for the growth of bacterial colonies. The antibacterial activity of the ethanol extract was carried out following the Kirby-Bauer disk-diffusion method in Mueller-Hinton agar to measure bacterial sensitivity. A value of P < 0.05 was considered statistically significant.

RESULTS

Evaluation of the antibacterial effect of EEE and EES at 24 and 48 h showed that a concentration of 75% for both groups had the highest antimicrobial activity against S. mutans (11.2 ± 0.7 mm; 11.6 ± 0.5 mm and 11.3 ± 0.7 mm; 11.8 ± 0.5 mm, respectively). So, the results have shown that the concentration of EEE and EES of 75% has a greater efficacy than the concentration of 50%, but both concentrations are not as effective as chlorhexidine.

CONCLUSION

EEE and EES at concentrations of 50% and 75% present antibacterial activity against S. mutans ATCC 25175.

Oral Microbiome of Children Living in an Isolated Area in Myanmar

Several studies have shown that the oral microbiome is related to systemic health, and a co-relation with several specific diseases has been suggested. The oral microbiome depends on environmental- and community-level factors. In this observational study, the oral microbiomes of children of isolated mountain people were analyzed with respect to the core oral microbiome and etiology of dental caries. We collected samples of supragingival plaque from children (age 9–13) living in the Chin state of Myanmar. After DNA extraction and purification, next-generation sequencing of the V3–V4 hypervariable regions of the 16S rRNA was conducted. From thirteen subjects, 263,458 valid reads and 640 operational taxonomic units were generated at a 97% identity cut-off value. At the phylum level, Proteobacteria was the most abundant, followed by Firmicutes and Bacteroides. Forty-four bacteria were detected in total from all the subjects. For children without dental caries, Proteobacteria was abundant. In contrast, in children with dental caries, Firmicutes and Bacteroides were abundant. The oral microbiome of children living in an isolated area may be affected by environmental- and community-level factors. Additionally, the composition of the oral microbiome may affect the risk of dental caries.