Potential effects of specific gut microbiota on periodontal disease: a two-sample bidirectional Mendelian randomization study.

Introduction: Periodontal disease (PD) presents a substantial global health challenge, encompassing conditions from reversible gingivitis to irreversible periodontitis, often culminating in tooth loss. The gut-oral axis has recently emerged as a focal point, with potential gut microbiota dysbiosis exacerbating PD. Methods: In this study, we employed a double-sample bidirectional Mendelian randomized (MR) approach to investigate the causal relationship between specific gut microbiota and periodontal disease (PD) and bleeding gum (BG) development, while exploring the interplay between periodontal health and the gut microenvironment. We performed genome-wide association studies (GWAS) with two cohorts, totalling 346,731 (PD and control) and 461,113 (BG and control) participants, along with data from 14,306 participants' intestinal flora GWAS, encompassing 148 traits (31 families and 117 genera). Three MR methods were used to assess causality, with the in-verse-variance-weighted (IVW) measure as the primary outcome. Cochrane's Q test, MR-Egger, and MR-PRESSO global tests were used to detect heterogeneity and pleiotropy. The leave-one-out method was used to test the stability of the MR results. An F-statistic greater than 10 was accepted for instrument exposure association. Results and conclusion: Specifically, Eubacterium xylanophilum and Lachnoclostridium were associated with reduced gum bleeding risk, whereas Anaerotruncus, Eisenbergiella, and Phascolarctobacterium were linked to reduced PD risk. Conversely, Fusicatenibacter was associated with an elevated risk of PD. No significant heterogeneity or pleiotropy was detected. In conclusion, our MR analysis pinpointed specific gut flora with causal connections to PD, offering potential avenues for oral health interventions.

Amplification and up-regulation of microRNA-30b in oral squamous cell cancers.

OBJECTIVES: MicroRNAs (miRNAs) are negative regulators of protein coding genes which are frequently deregulated in mammary cancers. Over-expression of microRNA-30b (hsa-miR-30b) is implicated in tumour invasion and immunosuppression during metastasis. The chromosome locus of MIR30B gene, 8q24, is frequently amplified in oral squamous cell cancers (OSCCs). In the present study, we aimed to investigate the copy number variations as well as expression levels of MIR30B gene in OSCCs and analyse their correlation with tumour stage. DESIGN: Quantitative real-time PCR was performed to examine the copy number of MIR-30B gene as well as hsa-miR-30b expression in 107 OSCC samples with matched adjacent normal tissues. Proportional odds regression and two-way repeated measurement ANOVA were used to analyse the association between copy number variations (CNVs) and hsa-miR-30b expression. RESULTS: Copy number gains of MIR-30B gene were detected in a relatively large percentage of the OSCC samples (27.1%, 29 out of 107) and were correlated with tumour stages (p<0.001). MIR30B gene amplification also showed a close correlation with hsa-miR-30b over-expression in OSCCs (p<0.001). On the other hand, enhanced miR-30b expression was also detected in a group of OSCC samples with unaltered copy number of MIR30B gene. CONCLUSIONS: Copy number increase of MIR30B is frequent in advanced OSCC and is correlated with hsa-miR-30b over-expression. Sporadic OSCCs can exhibit different mechanisms of MIR30B regulation.

[A comparison of rapid palatal expansion and Damon appliance on non-extraction correction of dental crowding].

PURPOSE: To compare the effect of rapid palatal expansion (RPE) and Damon technique on the correction of dental crowding with non-extraction approach. METHODS: 19 adolescent patients with non-extraction orthodontic treatment were reviewed. They had Class I skeletal pattern and moderate crowding. Nine subjects were treated with RPE followed by straight wire appliance, and 10 subjects were treated with Damon appliance only. The dental casts and cephalometric radiophotographs were measured before and after the treatment. The difference between two groups was analyzed for Student's t test with SPSS15.0 software package. RESULTS: Upper and lower inter-canine width increased 2.9mm and 1.3mm respectively in RPE group (P<0.05), while there was no significant change in Damon group. A significant posterior expansion of upper and lower arch width was noted in both RPE and Damon groups (P<0.05). The increase in upper inter-bicuspid width and lower inter-molar width was comparable in two groups. The upper inter-molar width in RPE group expanded 5.3mm, which was significantly larger than that of 3.1mm in Damon group(P<0.05). The increase in lower inter-bicuspid width in Damon group, on the other hand, was larger than that of RPE group (4.5mm vs. 1.5mm). (P<0.05) Both groups showed buccal tipping of bicuspids and molars, with more extend of bicuspid tipping in Damon group (P<0.05). The maxillary base width increased 2.1mm in RPE group, which was significantly larger than that of 0.6mm in Damon group (P<0.05). The upper and lower incisors in Damon group were tipped forward by 9.2 degrees and 7.5 degrees respectively, while the change in RPE group was not significant (P<0.05). CONCLUSION: Both RPE and Damon technique can successfully increase the arch width and correct moderate dental crowding with non-extraction approach. Damon appliance protrudes the upper and lower incisors and expands the dental arch by buccal tipping of bicuspids and molars. RPE expands the maxillary base along with the whole upper dental arch and could maintain the incisors in upright position.

[Arch perimeter changes on non-extraction correction of dental crowding with Damon appliance].

PURPOSE: To clarify the arch perimeter changes and the mechanism of Damon technique on the correction of dental crowding with non-extraction approach in different dental stages. METHODS: 24 patients with non-extraction Damon appliance treatment were reviewed. They had Class I skeletal pattern and upper arch crowding more than 5mm. They were divided into 2 groups according to the eruption of upper second molars, with 9 subjects in group G1 (second molar unerupted) and 15 subjects in group G2 (second molar erupted). The dental casts and cephalometric radiophotographs were analyzed before and after the upper arch crowding correction. The difference between the two groups was analyzed with SPSS15.0 software package. RESULTS: Significant increase in upper arch length and arch width were noted after the correction of crowding, with no significantly difference between the two groups. Stepwise regression analysis indicated that the increase in arch length (X1) and inter-bicuspid arch width (X2) were predictive of the increase in arch perimeter (Y), with the equation of Y=1.35X1+0.63X2+1.77. Both molar distalization and incisor protrusion contributed to the increase in arch length, which were 2.4mm and 1.2mm in G1 group, and 0.9mm and 2.5mm in G2 group. The difference between two groups was statistically significant (P<0.05). CONCLUSIONS: During the correction of upper arch crowding with non-extraction Damon technique, arch perimeter is gained by the increase in both arch length and inter-bicuspid arch width. In addition to the labial movement of incisors, space can be provided by the distal movement of the first molars before the eruption of second molars.

[The clinical implication of self-ligating brackets].

The self-ligating bracket is a new kind of bracket. The cardinal feature of a self-ligating bracket is an inbuilt metal labial face to the bracket slot, which is referred to as a clip or slide. It reduces the chairside time and makes the ligating easier. The lower sliding resistance offered by self-ligating bracket reduces the resistance to close the space and makes the treatment more efficient.Low friction and low force are good for the alveolar bone rebuilding physiologically. The spring clip of self-ligating bracket can control the tooth in three dimentional directions as the conventional fixed appliances. Most orthodontists think that self-ligating bracket allows shorter treatment time and longer intervals and less visits. There is no significance difference between the debonding and ligating loss rate of self-ligating bracket and conventional bracket.