Assessment of TNF-α (-857 C/T) gene polymorphism in oral lichen planus disease: A case-control study.

Background and aims: Oral lichen planus (OLP) is an inflammatory mucocutaneous disorder with an immune-mediated pathogenesis. The tumor necrosis factor-α (TNF-α) level in the serum of OLP patients is significantly higher than in the control group. TNF-α-857 C/T polymorphism can be related to the increased TNF-α level in blood circulation. This study investigated the relationship between TNF-α (-857 C/T) polymorphism and OLP patients in an Iranian population. Methods: Saliva samples were taken from 200 people, including 100 patients with OLP and 100 healthy people who did not have significant differences in age and sex. Then, DNA was extracted from them and the TNF-α (-857 C/T) genotype was identified using the polymerase chain reaction with confronting two-pair primers method. Statistical Package for the Social Sciences version 16 software analyzed the results. Results: The frequency of C/C, C/T, and T/T genotypes of the TNF-α-857 C/T polymorphism in the patient group were 78%, 18%, and 4%, respectively, and in the control group were 72%, 23%, and 5%, respectively. The differences between the two groups regarding allele (χ 2 = 0.97, p = 0.32) and genotype (χ 2 = 0.96, p = 0.62) frequency among the studied population were insignificant. Conclusion: This study showed that the difference in the frequency of single nucleotide polymorphism TNF-α-857 C/T polymorphism in the patient and control group had no significant relationship with the increased OLP incidence. Also, no significant association was observed between allele and genotype frequency of TNF-α (-857 C/T) with OLP subtypes.

Evaluation of the association between TNF-α-1031 T/C polymorphism with oral lichen planus disease.

BACKGROUND: Oral lichen planus (OLP) is a T-cell-mediated autoimmune disease that affects the epithelial cells of the oral cavity. This study was performed to investigate any possible relationship between - 1031(T/C) polymorphism (rs1799964) of the tumor necrosis factor α (TNF-α) gene with the risk and severity of oral lichen planus (OLP) disease among an Iranian population. METHOD: Saliva samples were collected from 100 patients with OLP and a similar number of healthy controls (age and sex-matched). Then, DNA was extracted from the collected samples for genotyping TNF-α-1031 T/C polymorphism using the PCR-CTPP method. The results were assessed using SPSS software. RESULTS: The findings revealed a significantly higher prevalence of the C allele in OLP patients (53%) compared to healthy controls (36%), suggesting an association between TNF-alpha gene polymorphism and OLP. A multivariate logistic regression analysis supported this finding, as the presence of the C allele was significantly associated with an increased risk of OLP [χ2 = 4.17, p = 0.04, 95% CI = 1.01-2.65, OR = 1.64]. However, our data indicated no significant association between TNF-alpha-1031 T/C gene polymorphism and OLP severity. CONCLUSIONS: These findings provide the first evidence supporting a possible role of TNF-α-1031 T/C gene polymorphism in OLP susceptibility in the Iranian population. The findings of this study demonstrate a positive association between TNF-α-1031 C/T allele distribution and the risk of OLP disease in the Iranian population. Therefore, carrying the C allele may increase the susceptibility to OLP disease.

Association between alcohol dehydrogenase polymorphisms (rs1229984, rs1573496, rs1154460, and rs284787) and susceptibility to head and neck cancers: A systematic review and meta-analysis.

OBJECTIVE: Head and neck cancer (HNC) is a prevalent and complex group of malignancies with increasing incidence globally. Alcohol dehydrogenases (ADHs) play a crucial role in alcohol metabolism, and their polymorphisms have been linked to HNC risk. This systematic review and meta-analysis aims to evaluate the association between ADH polymorphisms and susceptibility to HNCs, incorporating additional analyses and adding more studies to increase power and accuracy of the results. DESIGN: Subgroup analysis, meta-regression analysis, and sensitivity analyses were conducted to explore potential differences within the data and assess the stability of pooled odds ratios (ORs). To mitigate the risk of false conclusions from meta-analyses, a trial sequential analysis was performed. RESULTS: For ADH1B rs1229984, the pooled OR (95 % confidence interval (CI)) was 0.73 (0.65, 0.82), 0.42 (0.35, 0.50), 0.57 (0.44, 0.73), 0.56 (0.50, 0.62), and 0.80 (0.73, 0.88), as well as for ADH7 rs1573496, the pooled OR was 0.72 (0.62, 0.85), 0.36 (0.17, 0.74), 0.76 (0.64, 0.91), 0.80 (0.71, 0.91), and 0.38 (0.18, 0.78) with a p < 0.05 in all allelic, homozygous, heterozygous, recessive, and dominant models, respectively. However, no significant association was found between the ADH7 rs1154460 and rs284787 polymorphisms and the risk of HNC with pooled ORs of 1.11 (p = 0.19) and 1.09 (p = 0.24) for the recessive model, respectively. The ethnicities, tumor subsites, control sources, sample sizes, quality scores, and Hardy-Weinberg equilibrium statuses were confounding factors. CONCLUSION: The ADH1B rs1229984 and ADH7 rs1573496 polymorphisms are significantly associated with a reduced risk of HNC.

Association of interleukin-8 polymorphism (+ 781 C/T) with the risk of oral Lichen Planus disease.

BACKGROUND: Oral Lichen Planus (OLP) is a chronic inflammatory mucosal disease. The pathogenesis of OLP is unknown. The Single Nucleotide Polymorphism (SNP) that occurs in the regulatory position + 781 could affect the expression of interleukin-8. This polymorphism is probably associated with increased serum levels of IL-8. The current study aimed to investigate the genotype and allele frequencies of IL-8( + 781 C/T) in OLP patients and whether it is associated with the severity of OLP disease in an Iranian population. METHODS: Three milliliters of saliva were taken from 100 patients with OLP and 100 healthy individuals who were matched in age and gender. After DNA extraction from saliva samples of patients and healthy individuals, the genotype of IL-8 at position + 781 is detected using the PCR-RFLP method. The results were analyzed using SPSS software. RESULTS: Frequency of C/C, T/C, and T/T genotypes at position IL-8 + 781 gene in the patient group were 47%, 41%, and 12%, respectively, and in the control group, were 37%, 42%, and 21%. The difference between the two groups regarding allele frequency distribution was statistically significant (χ2 = 3.86, p = 0.049, 95% CI = 0.44-1, OR = 0.66). Our results indicated the significantly higher frequency of the TT genotype in the erosive OLP compared to the nonerosive group (p = 0.03, OR = 0.89, 95% CI = 0.49-1.6). CONCLUSION: This study depicted the difference in the frequency of SNP IL-8 + 781 C/T allele in the patient and control groups had a significant association with the risk of OLP. In addition, our data revealed that IL-8 + 781 C/T polymorphisms might be associated with the severity of OLP in the Iranian population.

Salivary and serum levels of soluble E-cadherin in patients with gastrointestinal cancers: A comparative study.

AIM: According to the literature, high levels of salivary soluble E-cadherin may be lined to advanced stage and poor prognosis in cancers. This research aimed at comparing salivary and serum levels of soluble E-cadherin in cases with esophageal, gastric, and colorectal cancers. METHODS: This case-control research was performed on 68 patients with gastrointestinal cancers and 57 healthy volunteers as a control group to measure salivary and serum levels of soluble E-cadherin using ELISA kits. RESULTS: The results showed a statistically significant difference between salivary and serum levels of soluble E-cadherin in the case group, as opposed to the control group (P = 0.031). The salivary level of soluble E-cadherin in the control group was 2.138 ng/mL on average lower than that that in the case group. The median salivary level of soluble E-cadherin among cases with lymph node involvement was significantly higher compared with its median level in the control group (P = 0.049). Soluble E-cadherin salivary level and other variables, such as metastasis and cancer stage, were directly correlated, but it was not statistically significant. CONCLUSION: According to the findings, the salivary level of soluble E-cadherin among cases with gastric cancer could be considered as a prognostic marker, but the diagnostic value of saliva could not be judged in esophageal and colorectal cancers because of small sample size, and more investigations are required for a definite conclusion.

A systematic review and meta-analysis on serum and salivary levels of total antioxidant capacity and C-reactive protein in oral lichen planus patients.

OBJECTIVE: Oral lichen planus (OLP) is an inflammatory disease that total antioxidant capacity (TAC) and C-reactive protein (CRP) play an important role in its pathogenesis. In this meta-analysis, we compared the salivary and serum levels of TAC and CRP between OLP patients and controls. DESIGN: A comprehensive search was performed in four databases (PubMed, Scopus, Web of Science, and Cochrane Library). Standardized mean difference (SMD) and 95% confidence intervals (CI) were computed by the RevMan 5.3. Sensitivity analysis, subgroup analysis, meta-regression, and publication bias were analyzed by the CMA 2.0. RESULTS: Nineteen articles were included in the meta-analysis. The pooled SMDs were -1.80 µmol/L (95%CI: -2.75, -0.85; p = 0.0002) and -2.56 µmol/L (95%CI: -4.40, -0.72; p = 0.006) for the salivary and serum levels of TAC, respectively. The SMDs for salivary and serum levels of CRP were 0.64 µg/L (95%CI: 0.35, 0.94; p < 0.0001) and 0.97 mg/L (95%CI: 0.56, 1.338; p < 0.00001), respectively. Geographical area based on the country was a significant factor in the subgroup analysis for salivary TAC level. There was adequate evidence supporting the occurrence of less salivary and serum TAC levels in OLP patients than controls, but the amount of information was inadequate to make valid conclusions for salivary CRP level. CONCLUSIONS: In OLP patients, salivary and serum levels of TAC is significantly lower while the salivary and serum levels of CRP is significantly higher than controls.

A Randomized Triple-Blind Clinical Trial of the Effect of Low-Level Laser Therapy on Infiltration Injection Pain in the Anterior Maxilla

Abstract Objective: To evaluate the level of pain experienced during infiltration anesthesia of the anterior maxilla following low-level laser therapy (LLLT) with 810-980 nm wavelengths. Material and Methods: In the current triple-blind clinical trial, 84 patients received a total of 168 infiltration anesthesia injections (1.8 mL of 2% lidocaine plus 1:100,000 epinephrine) in the anterior maxilla. Each patient received two injections into the buccal mucosa of the right and left central incisors with a two-week interval. One injection was performed after LLLT, while the other injection was administered conventionally without laser. The pain level was measured immediately after injection using a visual analog scale (VAS). Results: There was a significant difference in the pain level experienced with and without LLLT, such that the mean pain score following LLLT was significantly lower than that without LLLT (p<0.05). No significant difference was found in the pain level between laser and no laser groups in males, but the difference in this regard was significant in females (p<0.05) and female patients experienced a significantly lower level of pain following LLLT. Conclusion: The low-level laser therapy can be successfully used to decrease the level of pain experienced during infiltration anesthesia of the anterior maxilla (AU).

A meta-analysis and trial sequential analysis of serum copeptin level in adult patients with Obstructive Sleep Apnoea Syndrome.

OBJECTIVE: Copeptin can act as a stable biomarker in inflammation and stress response that obstructive sleep apnoea syndrome (OSAS), can induce oxidative stress and consequently promotes systemic inflammation. The purpose of the study is to appraise serum copeptin level in adult patients with OSAS compared to the controls. MATERIAL AND METHODS: Electronic search was done in the databases of PubMed/Medline, Web of Science, Scopus, and Cochrane Library until June 2021, without any restrictions. For comparison of the serum copeptin level between groups, the mean difference (MD) and 95% confidence interval (CI) were calculated by the Review Manager 5.3 software. Trial sequential analysis (TSA) was used by applying TSA software. RESULTS: Among the databases, five articles (involving 495 OSAS patients and 135 controls) were included. To report the serum copeptin level in OSAS patients compared to controls, the pooled OR became 12.21pg/mL (95%CI: 2.31 to 22.11; P=0.02) and also the pooled OR for comparison of serum copeptin level in severe versus moderate/mild OSAS patients was 5.96pg/mL (95%CI: 1.46 to 10.47; P=0.009). The results of TSA illustrated that the Z-curve has not crossed the monitoring boundary curves and did not reach the required information size. CONCLUSIONS: The main findings recommended that copeptin had a significantly higher serum level in OSAS patients compared to controls, as well as a significantly higher level in severe patients compared to mild/moderate OSAS patients for the serum level of copeptin.

Association between IL-8 (-251T/A) and IL-6 (-174G/C) Polymorphisms and Oral Cancer Susceptibility: A Systematic Review and Meta-Analysis.

BACKGROUND AND OBJECTIVE: Inflammation and cell-mediated immunity can have significant roles in different stages of carcinogenesis. The present meta-analysis aimed to evaluate the association between the polymorphisms of IL-8 (-251T/A) and IL-6 (-174G/C) and the risk of oral cancer (OC). METHODS: PubMed/MEDLINE, Web of Science, Cochrane Library, and Scopus databases were searched until December 18, 2020 without any restrictions. RevMan 5.3 software was used to calculate the results of forest plots (odds ratios (ORs) and 95% confidence intervals (CIs)); CMA 2.0 software was used to calculate funnel plots (Begg's and Egger's tests), and SPSS 22.0 was used for the meta-regression analysis. Moreover, trial sequential analysis was conducted to estimate the robustness of the results. RESULTS: Eleven articles including twelve studies were selected for the meta-analysis. The pooled ORs for the association between IL-8 (-251T/A) polymorphism and the risk of OC in the models of A vs. T, AA vs. TT, TA vs. TT, AA + TA vs. TT, and AA vs. TT + TA were 0.97 (p = 0.78), 0.86 (p = 0.55), 0.78 (p = 0.37), 0.83 (p = 0.45), and 1.10 (p = 0.34), respectively. The pooled ORs IL-6 (-174G/C) polymorphism and the risk of OC in the models of C vs. G, CC vs. GG, GC vs. GG, CC + GC vs. GG, and CC vs. GG + GC were 1.07 (p = 0.87), 1.17 (p = 0.82), 1.44 (p = 0.38), 1.28 (p = 0.61), and 0.96 (p = 0.93), respectively. There was no association between IL-8 (-251T/A) polymorphism and OC susceptibility, but the C allele and GC and CC genotypes of IL-6 (-174G/C) polymorphism were associated with the risk of OC based on subgroup analyses, that is to say, the source of control and the genotyping method might bias the pattern of association. CONCLUSIONS: The meta-analysis confirmed that there was no association between the polymorphisms of IL-6 (-174G/C) and IL-8 (-251T/A) and the susceptibility of OC. However, the source of control and the genotyping method could unfavorably impact on the association between the polymorphisms of IL-6 (-174G/C) and the risk OC.

A PRISMA-compliant meta-analysis on association between X-ray repair cross complementing (XRCC1, XRCC2, and XRCC3) polymorphisms and oral cancer susceptibility.

BACKGROUND: Oral Cancer (OC) is one of the leading causes of death and the disease mainly occurs over 50 years of age. Herein, a meta-analysis aimed to assess the association between X-ray repair cross complementing (XRCC) polymorphisms and OC risk. METHODS: Four databases were searched extensively until June 5, 2020. Subgroup analysis, meta-regression, and funnel plots, as well as the quality assessment were estimated. RESULTS: Fifteen studies were entered to the analysis. With regards to allele, homozygote, heterozygote, recessive, and dominant models, the pooled ORs for XRCC1 rs1799782 polymorphism were 1.51 (P = 0.01), 1.45 (P = 0.11), 1.45 (P = 0.0003), 1.44 (P = 0.0002), and 1.29 (P = 0.26); for XRCC1 rs1799782 polymorphism were 1.65 (P = 0.11), 1.50 (P = 0.33), 1.06 (P = 0.83), 1.57 (P = 0.12), and 1.32 (P = 0.45); for XRCC1 rs25489 polymorphism were 0.01 (P = 0.19), 1.44 (P = 0.48), 1.21 (P = 0.72), 1.17 (P = 0.19), and 1.38 (P = 0.54); for XRCC2 rs2040639 polymorphism were 0.68 (P = 0.0002), 0.63 (P = 0.02), 0.95 (P = 0.92), 0.79 (P = 0.49), and 0.61 (P = 0.005); and for XRCC3 rs861539 polymorphism were 1.24 (P = 0.20), 1.28 (P = 0.48), 0.99 (P = 0.95), 1.15 (P = 0.46), and 1.52 (P = 0.15), respectively. CONCLUSIONS: The T allele and CT genotype of XRCC1 rs1799782 polymorphism had an elevated risk, whereas the G allele and GG genotype of XRCC2 rs2040639 polymorphism had a protective role in OC.

An overview of recent progress in dental applications of zinc oxide nanoparticles.

Nanotechnology is an emerging field of science, engineering, and technology concerning the materials in nanoscale dimensions. Several materials are used in dentistry, which can be modified by applying nanotechnology. Nanotechnology has various applications in dentistry to achieve reliable treatment outcomes. The most common nanometals used in dental materials are gold, silver, copper oxide, magnesium oxide, iron oxide, cerium oxide, aluminum oxide, titanium dioxide, and zinc oxide (ZnO). ZnO nanoparticles (NPs), with their unparalleled properties such as high selectivity, enhanced cytotoxicity, biocompatibility, and easy synthesis as important materials were utilized in the field of dentistry. With this background, the present review aimed to discuss the current progress and gain an insight into applications of ZnO NPs in nanodentistry, including restorative, endodontic, implantology, periodontal, prosthodontics, and orthodontics fields.

Fabrication of a novel hydroxyapatite/polyether ether ketone surface nanocomposite via friction stir processing for orthopedic and dental applications.

There is increasing interest in the use of polyether ether ketone (PEEK) for orthopedic and dental implant applications due to its elastic modulus (close to that of bone), biocompatibility and radiolucent properties. However, PEEK is still categorized as bioinert owing to its low integration with surrounding tissues. Methods such as depositing hydroxyapatite (HA) onto the PEEK surface could increase its bioactivity. However, depositing HA without damaging the PEEK substrate is still required further investigation. Friction stir processing is a solid-state processing method that is widely used for composite substrate fabrication. In this study, a pinless tool was used to fabricate a HA/PEEK surface nanocomposite for orthopedic and dental applications. Microscopical images of the modified substrate confirmed homogenous distribution of the HA on the surface of the PEEK. The resultant HA/PEEK surface nanocomposites demonstrated improved surface hydrophilicity coupled with better apatite formation capacity (as shown in the simulated body fluid) in comparison to the pristine PEEK, making the newly developed material more suitable for biomedical application. This surface deposition method that is carried out at low temperature would not damage the PEEK substrate and thus could be a good alternative for existing commercial methods for PEEK surface modification.

Association of LTF, ENAM, and AMELX polymorphisms with dental caries susceptibility: a meta-analysis.

BACKGROUND: This meta-analysis evaluated the association of LTF, ENAM, and AMELX polymorphisms with dental caries susceptibility. METHODS: We searched the Scopus, PubMed/Medline, Web of Science, and Cochrane Library databases to retrieve articles published by October 2019. Review Manager 5.3 software was used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs). The results of publication bias tests were retrieved by Comprehensive Meta-Analysis 2.0 software. RESULTS: A total of 150 relevant records were identified; out of which, 16 were entered into the analysis (4 studies assessed LTF, 11 ENAM, and 11 AMELX polymorphisms). Of all polymorphisms, there was a significant association only between ENAM rs3796704 polymorphism and dental caries susceptibility. Both ENAM rs3796704 and AMELX rs17878486 polymorphisms had a significant association with dental caries risk in the Caucasian ethnicity and the studies including caries-free control group. CONCLUSIONS: The results of this meta-analysis showed that the G allele and the GG genotype of ENAM rs3796704 were associated with an increased risk of caries in the case group compared with the control group. But there was no association between LTF rs1126478, ENAM (rs1264848 and rs3796703), and AMELX (rs946252, rs17878486, and rs2106416) polymorphisms and dental caries susceptibility.

Optimum synthesis of polyhydroxybutyrate-Co3O4 bionanocomposite with the highest antibacterial activity against multidrug resistant bacteria.

Increased multidrug resistant (MDR) bacteria are considered one of the most challenging problems of the present century. The present study aimed to identify the optimum conditions for synthesis of Polyhydroxybutyrate-Co3O4 bionanocomposite with the highest antibacterial activity via in situ synthesis. Nine experiments with different amounts of polyhydroxybutyrate (PHB) biopolymer and Co3O4 nanoparticles and different stirring times were designed using Taguchi method. The antibacterial activity of synthesized nanocomposites against Staphylococcus aureus and Escherichia coli was evaluated using colony forming units (CFU) and disc diffusion methods. The characterizations of products were studied by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The synthesized bionanocomposites completely prevented the growth of bacteria under the conditions of experiments 5 (Co3O4 4 mg/ml, PHB 1 mg/ml and stirring time: 90 min) and 9 (Co3O4 8 mg/ml, PHB 2 mg/ml and stirring time: 60 min). The results showed that nanocomposite formation improved structural properties, thermal stability and antibacterial activity. PHB-Co3O4 bionanocomposite can be used in various fields of pharmacy, medicine and dentistry due to its desirable antibacterial properties.

A meta-analysis and meta-regression of association between MTHFR A1298C polymorphism and nonsyndromic cleft lip/palate risk: An evaluation based on five genetic models.

OBJECTIVE: The present meta-analysis is intended to assess the association between NSCL/P risk and methylenetetrahydrofolate reductase (MTHFR) A1298C polymorphism in case-control studies. MATERIALS AND METHODS: The Web of Science, PubMed/Medline, Scopus, and Cochrane Library databases were searched for related articles published by April 2019. Review Manager 5.3 was applied to measure the odds ratios (ORs) with 95% confidence interval (CI) in the analyses assessing the strength of the association between A1298C polymorphism and NSCL/P risk. Results Sixteen studies were involved and analysed in this meta-analysis. Altogether, the reviewed articles included 2677 NSCL/P patients and 3669 controls. The pooled ORs of the allele, homozygote, heterozygote, dominant, and recessive models were 1.11 (95% CI: 0.94, 1.30; P=0.21), 1.14 (95% CI: 0.94, 1.37; P=0.18), 0.98 (95% CI: 0.80, 1.20; P=0.87), 1.03 (95% CI: 0.86, 1.22; P=0.79), and 1.18 (95% CI: 0.99, 1.41; P=0.07), respectively. The analysis did not identify any significant association between the polymorphism and the risk of NSCL/P in any ethnicity or source of controls. CONCLUSIONS: This meta-analysis revealed that A1298C polymorphism is not associated with NSCL/P susceptibility, and the subgroup analyses based on ethnicity and the source of cases further confirmed this result.

The Relationship Between the VARK Learning Styles and Academic Achievement in Dental Students.

BACKGROUND: Learning style is a factor influencing academic achievement. There are contradictory results in studies on the relationship between learning styles and academic achievement. The current study aimed at investigating the relationship between learning styles and academic achievement in dental students. METHODS: In the current descriptive-analytical study, 184 dental students were selected by simple random sampling. The VARK questionnaire was used as the data collection tool. The grade point average (GPA) of previous semester was used as an indicator of academic achievement, and accordingly, students were divided into two groups of strong (GPA ≥15) and weak (GPA ≤14.99). RESULTS: The most common learning styles in strong students were unimodal (n = 55, 42%) and bimodal (n = 41, 31.3%), while they were unimodal (n = 28, 47.2%) and bimodal (n = 24, 45.3%) in the weak students. There was no significant relationship between learning styles and academic achievement in the two groups of strong and weak students. CONCLUSION: No significant relationship was found between learning style and academic achievement. Further studies with larger sample sizes are recommended. Further studies with larger sample sizes are recommended.

Methylenetetrahydrofolate reductase C677T polymorphism is not associated with the risk of nonsyndromic cleft lip/palate: An updated meta-analysis.

Both genetic and environmental factors affect the risk of orofacial clefts. The present meta-analysis aimed to evaluate the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and risk of nonsyndromic cleft lip/palate (NSCL/P) in cases-control studies. The PubMed/Medline, Scopus, Web of Science, and Cochrane Library databases were searched up to April 2019 with no restrictions. The odds ratios (ORs) and 95% confidence intervals (CIs) in all analyses were calculated by Review Manager 5.3 software. The funnel plot analysis was carried out by the Comprehensive Meta-Analysis version 2.0 software. Subgroup analysis, meta-regression, and sensitivity analysis were performed for the pooled analyses. Thirty-one studies reviewed in this meta-analysis included 4710 NSCL/P patients and 7271 controls. There was no significant association between MTHFR C677T polymorphism and NSCL/P susceptibility related to allelic model (OR = 1.04; P = 0.49), homozygote model (OR = 1.11; P = 0.35), heterozygote model (OR = 0.99; P = 0.91), dominant model (OR = 1.00; P = 0.96), or recessive model (OR = 1.08; P = 0.23). There was no significant association between MTHFR C677T polymorphism and NSCL/P susceptibility based on the ethnicity or the source of cases. There was a significant linear relationship between the year of publication and log ORs for the allele model. The results of the present meta-analysis failed to show an association between MTHFR C677T polymorphism and NSCL/P susceptibility. The subgroup analyses based on the ethnicity and the source of cases further confirmed this result.