MTT versus other cell viability assays to evaluate the biocompatibility of root canal filling materials: a systematic review.

OBJECTIVES: This systematic review aimed to compare the cytotoxicity of root canal filling materials (RCFMs) assessed using tetrazolium salt-based tests (TSBT), including the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, with those obtained using other cell viability assays. METHODS: A search was performed on PubMed, Scopus, Web of Science and OpenGrey up to March 2019, followed by a manual search. According to the Participants, Exposure, Comparator and Outcomes (PECO) criteria, in vitro studies that evaluated the cytotoxic effect of RCFMss on animal and/or human cells through TSBT and at least one other viability assay were compared. The methodological quality of selected papers was assessed using ToxRTool® and SciRAP® . Data were analysed using Wilcoxon's signed-rank test for paired samples and linear weighting kappa. RESULTS: A total of 230 non-duplicated records were identified. After applying the eligibility criteria, 55 studies were selected for methodological evaluation, seven were selected by manual searching, 22 were excluded for methodological reasons, and 40 were included. A total of 410 comparisons were performed between TSBT and distinct cell viability tests (DCVT). MTT had moderate concordance with DCVT using human cells (n = 138 samples) (P = 0.507; k = 0.4225) and animal cells (n = 122 samples) (P = 0.124; k = 0.5775). XTT had good concordance using human (n = 110 samples) (P = 0.507; k = 0.6336) and animal cells (n = 12 samples) (P = 0.564; k = 0.6604). MTT, XTT, WST and MTS assays showed moderate concordance with DCVT (n = 410 samples) (P = 0.375; k = 0.5138) and complete agreement in 226 samples. DISCUSSION: The included studies had methodological heterogeneity that was minimized by the systematic review methodology. CONCLUSIONS: MTT and XTT do not cause over- or underestimation of cell viability during cytotoxicity screening of root canal filling materials, implying that these assays can be considered reliable for this purpose. Nonetheless, the development of protocols for the cytotoxic screening of these materials on 3D tissue-like cultures aiming to improve their predictability in the clinical scenario is suggested.

Evaluation of the palate dimensions of patients with perennial allergic rhinitis.

OBJECTIVE: The purpose of this study was to compare the transverse and vertical palate dimensions of two groups of children, one diagnosed as having perennial allergic rhinitis (PAR) and the other without any respiratory pathology. DESIGN: Case-control study. SETTING: Institute of Paediatrics and Child Care of the Federal University of Rio de Janeiro. SAMPLE AND METHODS: The sample consisted of 101 children with the diagnoses of PAR (mean age 6.5) and 91 without any respiratory pathology (mean age 7.3). From 192 patients, 65% was in mixed dentition phase and 35% in primary dentition. Each subject underwent an intra-oral clinical examination using three-dimensional Korkhaus compass to measure the intermolar distance, intercanine distance and palate depth. RESULTS: The allergic group showed greater averages of palate depth (P = 0.00), both in the primary dentition phase (11.53 mm x 10 mm) and in the mixed dentition (11.96 mm x 10.21 mm). There was no statistically significant difference for intermolar and intercanine distances, either in primary or mixed dentition (P > 0.05). CONCLUSION: The transverse dimension of the palate did not vary significantly between the groups, which seems to confirm that the main influence of alteration of the breathing pattern from nasal to mouth occurs on the vertical plane.