Association of polymorphisms in TNF-α, IL-1ß, GSTM and GSTT genes with apical periodontitis: is there a link with herpesviral infection?

AIM: To investigate the possible association between TNFα (-308 G/A) and IL-1ß (-511 C/T) single nucleotide polymorphisms (SNPs) and GSTT and GSTM deletion polymorphisms and risk of apical periodontitis (AP) development, and determine the association of different genotypes with the presence of herpesviral infection in AP. METHODOLOGY: The study included 120 periapical lesions and 200 control samples. Gene polymorphism analysis was performed using either polymerase chain reaction (PCR) or PCR/ restriction fragment length polymorphism (RFLP). Relative gene expression of TNF-α and IL-1ß was analysed using reverse transcriptase - real-time PCR. The presence of Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) was assessed by nested PCR. Chi-square and Fisher's exact tests and logistic regression analyses were done for polymorphisms, whilst Mann-Whitney U-test was performed for the expression analysis. The expected frequency of variants was analysed by the Hardy-Weinberg equilibrium test. RESULTS: TNF-α (-308 G/A) SNP increased AP susceptibility for heterozygous (odds ratio (OR) = 1.72, 95% confidence interval (CI) = 1.06-2.80, P = 0.027) and homozygous (OR = 8.55, 95% CI = 1.77-41.36, P < 0.001) carriers of the variant A allele. On the other hand, IL-1ß (-511 C/T) polymorphism exerted a protective effect both in heterozygotes (OR = 0.540, 95% CI = 0.332-0.880, P = 0.013) and homozygotes (OR = 0.114, 95% CI = 0.026-0.501, P < 0.001). In addition, GSTM1 and GSTT1 null genotypes separately, as well as concomitantly, were associated with an increased risk for AP development (P < 0.001). The null GSTT1 genotype increased approximately twice the risk of Epstein-Barr infection (EBV) in AP (OR = 2.17, 95% CI = 1-4.71, P = 0.048), whilst TNF-α SNP decreased it, both in heterozygotes (OR = 0.20, 95% CI = 0.08-0.48, P < 0.001) and AA homozygotes (OR = 0.07, 95% CI = 0.01-0.37, P = 0.001). CONCLUSIONS: GSTM and GSTT deletion polymorphisms, as well as TNFα (-308 G/A) SNP, are associated with increased risk, whereas IL-1ß (-511 C/T) polymorphism decreases the risk of AP development. GSTT and TNFα polymorphisms also appear to modulate the risk of EBV infection in Serbian patients with AP.

Levels of oxidative stress biomarkers and bone resorption regulators in apical periodontitis lesions infected by Epstein-Barr virus.

AIM: To investigate whether apical periodontitis lesions infected by Epstein-Barr virus (EBV) exhibit higher levels of oxidative stress biomarkers [8-hydroxydeoxyguanosine (8-OHdG) and oxidized glutathione (GSSG)] and bone resorption regulators [receptor activator of nuclear factor (NF-κB) ligand (RANKL) and osteoprotegerin (OPG)] compared to EBV-negative periapical lesions and healthy pulp tissues. METHODOLOGY: The experimental group consisted of 30 EBV-positive and 30 EBV-negative periapical lesions collected in conjunction with apicoectomy. The pulp tissues of 20 impacted third molars were used as healthy controls. The qualitative and quantitative analysis of EBV was performed by nested and real-time polymerase chain reaction (PCR), respectively. The levels of RANKL and OPG were analysed by reverse transcriptase real-time PCR. The levels of 8-OHdG and GSSG were determined by enzyme-linked immunosorbent assay (ELISA). Mann-Whitney U-test and Spearman's correlation were used for statistical analysis. RESULTS: The levels of RANKL, OPG, 8-OHdG and GSSG were significantly higher in apical periodontitis lesions compared to healthy pulp controls (P = 0.001, P < 0.001, P < 0.001 and P < 0.05, respectively). RANKL and OPG mRNA expression was significantly higher in EBV-positive compared to EBV-negative periapical lesions (P < 0.05). There was no significant correlation between EBV copy numbers and levels of RANKL, OPG, 8OH-dG and GSSG in apical periodontitis. CONCLUSION: Levels of bone resorption regulators and oxidative stress biomarkers were increased in apical periodontitis compared to healthy pulp tissues. EBV-positive periapical lesions exhibited higher levels of RANKL and OPG compared to EBV-negative periapical lesions. EBV may contribute to progression of apical periodontitis via enhanced production of bone resorption regulators.

Clinical reproducibility of three electronic apex locators.

AIM: To compare the reproducibility of three electronic apex locators (EALs), Dentaport ZX, RomiApex A-15 and Raypex 5, under clinical conditions. METHODOLOGY: Forty-eight root canals of incisors, canines and premolars with or without radiographically confirmed periapical lesions required root canal treatment in 42 patients. In each root canal, all three EALs were used to determine the working length (WL) that was defined as the zero reading and indicated by 'Apex', '0.0' or 'red square' markings on the EAL display. A new K-file of the same size was used for each measurement. The file length was fixed with a rubber stop and measured to an accuracy of 0.01 mm. Measurements were undertaken by two calibrated operators. Differences in zero readings between the three EALs in the same root canal were statistically analysed using paired t-tests with the Bonferroni correction, Bland-Altman plot and Linn's concordance correlation coefficients at α = 0.05. RESULTS: Mean and standard deviation values measured by the three EALs showed no statistically significant differences. Identical readings by all three EALs were found in 10.4% of root canals. Forty-three per cent of readings differed by less than ± 0.5 mm and 31.3% exceeded a difference of ± 1 mm. CONCLUSIONS: The clinical reproducibility of Dentaport ZX, RomiApex A-15 and Raypex 5 was confirmed with the majority of readings within the ± 1.0 mm range. However, the small number of identical zero readings suggests that EALs are not reliable as the sole means of WL determination under clinical conditions.