The oral-gut-circulatory axis: from homeostasis to colon cancer

The human microbiota is widely recognized as providing crucial health benefits to its host, specifically by modulating immune homeostasis. Microbial imbalance, known as dysbiosis, is linked to several conditions in the body. The oral cavity and gut host the two largest microbial communities playing a major role in microbial-associated diseases. While the oral-gut axis has been previously explored, our review uniquely highlights the significance of incorporating the circulatory system into this axis. The interaction between immune cells, inflammatory factors, circulating bacteria, and microbial metabolites influences the homeostasis of both the oral and gut microbiota in a bidirectional manner. In this comprehensive review, we aim to describe the bacterial components of the oral-gut-circulatory axis in both health and disease, with a specific focus on colon cancer.

Microbiome and colorectal carcinogenesis: Linked mechanisms and racial differences

Various studies have shown the interplay between the intestinal microbiome, environmental factors, and genetic changes in colorectal cancer (CRC) development. In this review, we highlight the various gut and oral microbiota associated with CRC and colorectal adenomas, and their proposed molecular mechanisms in relation to the processes of “the hallmarks of cancer”, and differences in microbial diversity and abundance between race/ethnicity. Patients with CRC showed increased levels of Bacteroides, Prevotella, Escherichia coli, enterotoxigenic Bacteroides fragilis, Streptococcus gallolyticus, Enterococcus faecalis, Fusobacterium nucleatum (F. nucleatum) and Clostridium difficile. Higher levels of Bacteroides have been found in African American (AA) compared to Caucasian American (CA) patients. Pro-inflammatory bacteria such as F. nucleatum and Enterobacter species were significantly higher in AAs. Also, AA patients have been shown to have decreased microbial diversity compared to CA patients. Some studies have shown that using microbiome profiles in conjunction with certain risk factors such as age, race and body mass index may help predict healthy colon vs one with adenomas or carcinomas. Periodontitis is one of the most common bacterial infections in humans and is more prevalent in Non-Hispanic-Blacks as compared to Non-Hispanic Whites. This condition causes increased systemic inflammation, immune dysregulation, gut microbiota dysbiosis and thereby possibly influencing colorectal carcinogenesis. Periodontal-associated bacteria such as Fusobacterium, Prevotella, Bacteroides and Porphyromonas have been found in CRC tissues and in feces of CRC patients. Therefore, a deeper understanding of the association between oral and gastrointestinal bacterial profile, in addition to identifying prevalent bacteria in patients with CRC and the differences observed in ethnicity/race, may play a pivotal role in predicting incidence, prognosis, and lead to the development of new treatments.

Comparison of visual analog shade matching, a digital visual method with a cross-polarized light filter, and a spectrophotometer for dental color matching

STATEMENT OF PROBLEM

During the selection of tooth color, subjective communication with the laboratory and an incorrect color registration technique can lead to a poor color match of a restoration to adjacent teeth and oral structures.

PURPOSE

The purpose of this cross-sectional study was to compare color registration and color matching in a young Chilean population with 3 different methods: visual with a shade guide, digital visual with a cross-polarized filter, and instrumental with a spectrophotometer.

MATERIAL AND METHODS

A total of 60 young volunteers were selected for tooth color registration of the maxillary right central incisor by using 3 different methods. Tooth color registration was performed using the CIELab and ΔE coordinate system.

RESULTS

Significant differences were detected between the coordinates recorded by the visual analog method in comparison with the other 2 methods. In contrast, no significant differences were found between the L∗ and b∗ coordinates of the spectrophotometer and the digital visual method with use of a cross-polarization filter. The ΔE obtained between the visual shade and spectrophotometer was 7.35, and the ΔE between the digital visual method with the use of a cross-polarization filter and the spectrophotometer was 6.12.

CONCLUSIONS

No statistically significant differences were observed in the digital image with the cross-polarization filter and the spectrophotometer in the L∗ and b∗ coordinate of the CIELab system. In contrast, the visual analog method led to large differences with the other methods under study. The ΔE of the digital visual method with the use of cross-polarization filters and the spectrophotometer was 6.2, considered as an acceptable color mismatch (<ΔE 6.8).

Layperson's preference of the transverse occlusal plane in asymmetric facial model

OBJECTIVE

Facial asymmetries are common, especially deviated nose and chin. The clinician must consider these variables when establishing the smile, placement and angulation of the occlusal plane. The purpose of this article is to determine if nose and chin deviations affect the perception of laypeople towards different angulations of the occlusal plane cant.

MATERIALS AND METHOD

An asymmetric facial model was created from a symmetric facial model used in a previous study. Nose and chin were deviated 3 mm to the left and eight different pictures were created, each with different degrees of occlusal plane cant in both direction. Using a visual Likert scale delivered via Websurvey within the private practice setting, 120 randomly selected laypersons evaluated each image according to their own beauty preferences.

RESULTS

In an asymmetric face, nose and chin deviated 3 mm to the left, a minor occlusal plane angulation of 2° can be perceptible regardless of the direction of the cant.

CONCLUSIONS

The occlusal plane should be as parallel to the interpupillary line as possible. If occlusal cant is present, less than 2° of angulation it is preferable, regardless of the direction of the nose and chin.

CLINICAL SIGNIFICANCE

In the presence of an asymmetric face, the occlusal plane should be as parallel as possible to the interpupillary line. The direction of the deviation of the nose and the chin are irrelevant factors to determine the occlusal plane. An inclination of the occlusal plane can cause vertical discrepancy, which could subsequently create malocclusion. A complete dentofacial analysis can aim at assessing the angulation of the occlusal plane not only for esthetic outcomes, but for also allowing correct occlusal function.