Spin and reporting in systematic reviews with meta-analysis of randomized clinical trials in restorative dentistry.

OBJECTIVE: To estimate the prevalence of spin and completeness of reporting of systematic reviews with metanalysis (SRMAs) in restorative dentistry. METHODS: Inclusion criteria were SRMAs of randomized clinical trials of restorative dentistry on survival, success, or failure rates of treatment in humans, with no language or year restriction. SRMAs performed with non-RCTs were excluded. PubMed/MEDLINE, Web of Science, Scopus, Embase, and Cochrane Collaboration Library were searched from inception to April 2022. Outcomes were the prevalence of spin (primary outcome) and completeness of reporting (secondary outcome) in the abstract and full text. Data were reported through means and standard deviations or absolute and relative frequencies. Spin in each item was considered low when occurring in less than 25% of the papers, moderate (25 to 75%), or high (more than 75%). RESULTS: We identified 7029 studies and 49 unique manuscripts were included. There was a moderate presence of spin in the abstracts and low in full texts. In the abstracts, 65.9% did not report adverse events; while in the abstract and full text, more than 16% reported a conclusion containing recommendations for clinical practice not supported by the findings. Regarding completeness of reporting, there was poor reporting for most items in the abstract while there was an adequate report in full texts, except for register name and registration number (not reported in 32.7%). CONCLUSIONS: Abstract of SRMAs in restorative dentistry should be better reported. Spin and poor reporting were more frequent in the abstracts, which misleads readers and could lead to inadequate clinical recommendations. CLINICAL SIGNIFICANCE: Spin and incomplete reporting are a threat to evidence-based practice, especially in systematic reviews. Therefore, care providers, researchers, and other stakeholders should be aware of the possibility of spin in systematic reviews and other sources to prevent misinterpretation, which could lead to inadequate decisions and treatments.

1,3-Diethyl-2-thiobarbituric acid as an alternative coinitiator for acidic photopolymerizable dental materials.

The ethyl-4-dimethylaminobenzoate (EDAB) is widely used as a coinitiator of the camphorquinone (CQ), but in acidic circumstances it might present some instability, reducing the polymerization efficiency of the material. Considering this, new coinitiators are being evaluated. Hence, this study evaluated the kinetic of polymerization (KP), the degree of conversion (DC), and the rate of polymerization (RP ) of experimental resin adhesives containing 1,3-diethyl-2-thiobarbituric acid (TBA) as a coinitiator of the CQ. The experimental monomeric blend was prepared with bisphenol A glycidyl dimethacrylate, 2-hydroxyethyl methacrylate, and acidic monomers. CQ was added at 1 mol % as photoinitiator. Six groups were formulated: four containing concentrations of 0.1, 0.5, 1, and 2 mol % of TBA, one without coinitiator, and the last one containing 1 mol % of EDAB (control group). The KP and the RP were performed using real-time Fourier Transform infrared spectroscopy. The group without coinitiator has not formed a polymer, whereas the addition of TBA resulted in the conversion of monomers in polymer. The DC of the adhesives was as higher as the increase in the TBA content. The group with 2 mol % of TBA presented improved DC and reactivity (RP ) than the other groups and the control one. Hence, the TBA has performed as a coinitiator of the CQ for the radical polymerization of methacrylate resin adhesives and it has improved the DC and the reactivity of the materials. Thus, it is a potential coinitiator for the photopolymerization of dental materials.

Polymerization kinetics and reactivity of alternative initiators systems for use in light-activated dental resins.

OBJECTIVES: The purpose of this study was to evaluate the reactivity and polymerization kinetics behavior of a model dental adhesive resin with water-soluble initiator systems. METHODS: A monomer blend based on Bis-GMA, TEGDMA and HEMA was used as a model dental adhesive resin, which was polymerized using a thioxanthone type (QTX) as a photoinitiator. Binary and ternary photoinitiator systems were formulated using 1mol% of each initiator. The co-initiators used in this study were ethyl 4-dimethylaminobenzoate (EDAB), diphenyliodonium hexafluorophosphate (DPIHFP), 1,3-diethyl-2-thiobarbituric acid (BARB), p-toluenesulfinic acid and sodium salt hydrate (SULF). Absorption spectra of the initiators were measured using a UV-Vis spectrophotometer, and the photon absorption energy (PAE) was calculated. The binary system camphorquinone (CQ)/amine was used as a reference group (control). Twelve groups were tested in triplicate. Fourier-transform infrared spectroscopy (FTIR) was used to investigate the polymerization reaction during the photoactivation period to obtain the degree of conversion (DC) and maximum polymerization rate (R(p)(max)) profile of the model resin. RESULTS: In the analyzed absorption profiles, the absorption spectrum of QTX is almost entirely localized in the UV region, whereas that of CQ is in the visible range. With respect to binary systems, CQ+EDAB exhibited higher DC and R(p)(max) values. In formulations that contained ternary initiator systems, the group CQ+QTX+EDAB was the only one of the investigated experimental groups that exhibited an R(p)(max) value greater than that of CQ+EDAB. The groups QTX+EDAB+DPIHFP and QTX+DPIHFP+SULF exhibited values similar to those of CQ+EDAB with respect to the final DC; however, they also exhibited lower reactivity. SIGNIFICANCE: Water-soluble initiator systems should be considered as alternatives to the widely used CQ/amine system in dentin adhesive formulations.