Is photobiomodulation effective during maxillary expansion? A systematic review and meta-analysis.

We performed a systematic review on literature associated with meta-analyses to elucidate whether (I) low-level laser therapy (C) compared to placebo accelerates (O) bone neoformation in the region of the midpalatal suture in (P) patients undergoing transverse maxillary expansion. Two reviewers blindly performed targeted searches using the selection criteria (PICOS) in seven major databases and three grey literature databases, employing specific terms and their entrenchments. The RevMan® software (Review Manager, version 5.3, Cochrane Collaboration) was used to adapt the RoB summary illustration to the Cochrane 2.0 tool questions. Meta-analysis was performed using standardized mean difference (SMD) and Cohen's d calculation on random effects, tests for heterogeneity (I2 ) and publication bias (Egger and Begg), and one-of-out sensitivity analysis. GRADE (Grading of Recommendations Assessment, Development and Evaluation) was used for evidence quality analysis. Among the five studies included in the qualitative synthesis, three were included in the meta-analysis. All analysed studies were prospective randomized clinical trials. The risk of bias was such that the Egger (P = .1991) and Begg (P = .024) tests showed no significant risk of publication bias. The meta-analysis showed high heterogeneity (I2  = 81%, P < .00001), and 3 months after the operation, there was no significant difference between the photobiomodulation (PBMT) group and control group (P = .850) or between the subgroups of the periods evaluated after 3 months (P = 0.490). GRADE showed an SMD of 0.62. Photobiomodulation as an adjuvant therapy in patients undergoing transverse maxillary expansion has few benefits and is limited in shape, as it contributes to bone healing in the midpalatal suture region after a period of 3 months.

Prevalence of malignant neoplastic oral lesions among children and adolescents: A systematic review and meta-analysis.

BACKGROUND: Malignant neoplasms that affect children and adolescents are predominantly embryonic and generally affect blood system cells and supporting tissues. AIM: This study aimed to summarize the scientific evidence about the prevalence of malignant lesions in the oral cavity of children and adolescents. DESIGN: In this systematic review and meta-analysis (PROSPERO CRD42020158338), data were obtained from seven databases and the gray literature. Cross-sectional observational studies on the prevalence of biopsied oral pediatric malignancies were included. The Newcastle-Ottawa Scale assessed the quality of the included studies, and the GRADE approach evaluated the evidence certainty. The meta-analysis prevalence was calculated using MedCalc® software, adopting a 95% confidence level (CI; random-effect model). RESULTS: Forty-two studies were included in the meta-analysis. Of the 64,522 biopsies, the prevalence of malignant lesions was 1.93% (n = 1,100; 95% CI = 1.21%-2.80%). Countries with a low socioeconomic profile showed the highest prevalence. The sample size did not influence the prevalence of oral malignancies, and unspecified lymphomas (12.08%; 95% CI = 5.73%-20.37%) and rhabdomyosarcoma (10.53%; 95% CI = 7.28%-14.30%) were the most common lesions. CONCLUSIONS: Oral malignant lesions biopsied in children and adolescents had a prevalence of <3%, and lymphomas and sarcomas were the most prevalent lesions.

Tissue methylation and demethylation influence translesion synthesis DNA polymerases (TLS) contributing to the genesis of chromosomal abnormalities in myelodysplastic syndrome.

AIMS: DNA methylation has its distribution influenced by DNA demethylation processes with the catalytic conversion of 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC). Myelodysplastic syndrome (MDS) has been associated with epigenetic dysregulation of genes related to DNA repair system, chronic immune response and cell cycle. METHODS: We evaluated the tissue DNA methylation/hydroxymethylation in bone marrow trephine biopsies of 73 patients with MDS, trying to correlate with the mRNA expression of 21 genes (POLH, POLL, REV3L, POLN, POLQ, POLI, POLK, IRF-1, IRF-2, IRF-3, IRF-4, IRF-5, IRF6, IRF-7, IRF-8,IRF-9, MAD2, CDC20, AURKA, AURKB and TPX2). RESULTS: The M-score (5mC) was significantly higher in patients with chromosomal abnormalities than patients with normal karyotype (95% CI -27.127779 to -2.368020; p=0.022). We observed a higher 5mC/5hmC ratio in patients classified as high-risk subtypes compared with low-risk subtypes (95% CI -72.922115 to -1.855662; p=0.040) as well as patients with hypercellular bone marrow compared with patients with normocellular/hypocellular bone marrow (95% CI -69.189259 to -0.511828; p=0.047) and with the presence of dyserythropoiesis (95% CI 17.077703 to 51.331388; p=0.001). DNA pols with translesion activity are significantly influenced by methylation. As 5mC immunoexpression increases, the expressions of POLH (r=-0.816; r2 =0.665; p=0.000), POLQ (r=-0.790; r2=0.624; p=0.001), PCNA (r=-0.635; r2=0.403; p=0.020), POLK (r=-0.633; r2=0.400; p=0.036 and REV1 (r=-0.578; r2=0.334; p=0.049) decrease. CONCLUSIONS: Our results confirm that there is an imbalance in the DNA methylation in MDS, influencing the development of chromosomal abnormalities which may be associated with the low expression of DNA polymerases with translesion synthesis polymerases activity.