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Molecular clocks help organisms to adapt important physiological functions to periodically changing conditions in the environment. These include the adaption of the 24 h sleep-wake rhythm to changes of day and night. The circadian clock is known to act as a key regulator in processes of health and disease in different organs. The knowledge on the circadian clock led to the development of chronopharmacology and chronotherapy. These fields aim to investigate how efficiency of medication and therapies can be improved based on circadian clock mechanisms. In this review we aim to highlight the role of the circadian clock in oral tissues and its potential in the different fields of dentistry including oral and maxillofacial surgery, restorative dentistry, endodontics, periodontics and orthodontics to trigger the evolving field of chronodentistry.

Background

Chronic infections have been reported to be risk factors for both coronary heart disease and ischemic stroke. DNA of oral bacteria, mainly from the viridans streptococci group, has been detected in coronary thrombus aspirates of myocardial infarction and cerebral aneurysms. Viridans streptococci are known to cause infective endocarditis and possess thrombogenic properties. We studied the presence of oral bacterial DNA in thrombus aspirates of patients with acute ischemic stroke treated with mechanical thrombectomy.

Methods and Results

Thrombus aspirates and arterial blood were taken from 75 patients (69% men; mean age, 67 years) with acute ischemic stroke. The presence of Streptococcus species, mainly the Streptococcus mitis group, belonging to viridans streptococci as well as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans in samples were determined using a quantitative polymerase chain reaction with specific primers and probes. The relative amount of bacterial DNA in a sample was determined with the comparative threshold cycle method. Bacterial DNA was detected in 84% (n=63) of aspired thrombi, and 16% (n=12) of samples were considered bacterial DNA negative. DNA of Streptococcus species, mainly the S mitis group, was found in 79% (n=59) of samples. The median relative amount of Streptococcus species DNA was 5.10-fold higher compared with the control blood samples from the same patients. All thrombi were negative for both P gingivalis and A actinomycetemcomitans.

Conclusions

This is the first study showing the common presence of bacterial DNA from viridans streptococci in aspired thrombi of patients with acute ischemic stroke. Streptococcal bacteria, mostly of oral origin, may contribute to the progression and thrombotic events of cerebrovascular diseases.

BACKGROUND:

This study aimed to identify anxiety in dental patients visiting a dental clinic using the Dental Anxiety Scale, their level of psychological distress using the Brief Symptom Inventory-18 and therefore identifying a correlation between these groups as well as their gender and age.

METHODS:

An adult sample of N = 1549 patients (865 females, 779 males) was examined over the course of three years using the Brief Symptom Inventory-18 to evaluate psychological distress and the Dental Anxiety Scale to determine anxiety before dental treatment. Evaluations were conducted according to age and gender.

RESULTS:

There was no correlation between different age groups of the sample the Dental Anxiety Scale. Anxiety, depression and GSI were more frequent in patients below the age of 46 than above. Women were more susceptible to signs of Anxiety and Somatization and scored higher on the Dental Anxiety Scale and the Global Severity Index than male patients. There was a significant positive correlation between scores of the BSI-18 categories: Somatization, Anxiety and Depression and the DAS for dental patients.

CONCLUSIONS:

This study showed that a relationship between dental anxiety and psychological distress exists. It would be an improvement to use a short questionnaire like the Dental Anxiety Scale to evaluate a patient before his first treatment so that more appropriate treatments can be pursued.

BACKGROUND:

The main objectives of this study were to describe and compare the microbiota of 1) deep dentinal lesions of deciduous teeth of children affected with severe early childhood caries (S-ECC) and 2) the unstimulated saliva of these children and 3) the unstimulated saliva of caries-free children, and to compare microbiota compositional differences and diversity of taxa in these sampled sites.

METHODS:

Children with S-ECC and without S-ECC were recruited. The saliva of all children with and without S-ECC was sampled along with the deep dentinal microbiota from children affected by S-ECC. The salivary microbiota of children affected by S-ECC (n = 68) was compared to that of caries-free children (n = 70), by Illumina MiSeq sequencing of 16S rRNA amplicons. Finally, the caries microbiota of deep dentinal lesions of those children with S-ECC was investigated.

RESULTS:

Using two beta diversity metrics (Bray Curtis dissimilarity and UniFrac distance), the caries microbiota was found to be distinct from that of either of the saliva groups (caries-free & caries-active) when bacterial abundance was taken into account. However, when the comparison was made by measuring only presence and absence of bacterial taxa, all three microbiota types separated. While the alpha diversity of the caries microbiota was lowest, the diversity difference between the caries samples and saliva samples was statistically significant (p < 0.001). The major phyla of the caries active dentinal microbiota were Firmicutes (median abundance value 33.5%) and Bacteroidetes (23.2%), with Neisseria (10.3%) being the most abundant genus, followed by Prevotella (10%). The caries-active salivary microbiota was dominated by Proteobacteria (median abundance value 38.2%) and Bacteroidetes (27.8%) with the most abundant genus being Neisseria (16.3%), followed by Porphyromonas (9.5%). Caries microbiota samples were characterized by high relative abundance of Streptococcus mutans, Prevotella spp., Bifidobacterium and Scardovia spp.

CONCLUSIONS:

Distinct differences between the caries microbiota and saliva microbiota were identified, with separation of both salivary groups (caries-active and caries-free) whereby rare taxa were highlighted. While the caries microbiota was less diverse than the salivary microbiota, the presence of these rare taxa could be the difference between health and disease in these children.

INTRODUCTION:
Apical periodontitis (AP) and cardiovascular diseases (CVDs) are chronic conditions triggered by an inflammatory process and sharing similar pathogeneses and molecular players. Previous studies have suggested that AP may perpetuate a systemic inflammation state and, in turn, contribute to CVD. In this study, we investigated the potential association between endodontic pathology and CVD using epidemiological and genetic approaches.

METHODS:
Epidemiologic analysis was performed by querying the medical and dental records of >2 million patients. We retrieved information on positive/negative history for endodontic pathologies and CVDs using diagnostic and treatment codes from a dental school-based and a hospital-based patient electronic health record system. A case-control genetic association study was also performed; 10 single nucleotide polymorphisms in genes identified as strongly associated with CVDs were genotyped in 195 cases with AP and 189 control individuals without AP. Data analyses were performed using the chi-square and Fisher exact tests. P ≤.05 indicates significant difference between groups.

RESULTS:
Significant associations were found between the presence of endodontic pathology and a history of hypertension, myocardial infarction, cerebrovascular accident, pacemaker, congestive heart failure, heart block, deep vein thrombosis, and cardiac surgery (0.0001 ≤ P ≤ .008). A modest association was found for heart murmur and atrial fibrillation (P = .04). A trend toward positive association (P = .05) was also found between AP and a single nucleotide polymorphism in KCNK3, a gene known to be involved in increased susceptibility to hypertension.

CONCLUSIONS:
Significant associations were found between endodontic pathology and various CVDs and CVD-related risk factors, particularly hypertension. A trend toward a positive association was also found between AP and KCNK3, suggesting that common genetic variations may underlie different diseases. Additional studies with larger sample sizes have the potential to elucidate common mechanisms underlying AP and CVD.