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AIM: To formulate and characterize the chemical structure of a new dental composite with photodimerized cinnamyl methacrylate (PD-CMA) photo-crosslinking comonomer and to evaluate the monomer-to-polymer conversion (MPC) and glass transition temperature (Tg) of the new composite copolymers. MATERIALS AND METHODS: CMA was PD by ultraviolet C-type (UVC) irradiation. The research groups were a control group C0 without PD-CMA and two trial groups: E10 (10 wt. % PD-CMA substituted in the base comonomers (B) and diluent (D) mixture); E20 (20 wt.% PD-CMA completely replacing the diluent (D) monomer). Infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies were employed for ascertaining copolymerization (CP). The surface features and composition of the copolymers were explained by field-emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy, respectively. The MPC and Tg of the copolymers were assessed using FTIR and differential scanning calorimetry, respectively. Statistical tests were used to compare the groups. RESULTS: The configuration of the new copolymers P (BD-Co-CMA) and P(B-Co-CMA) was confirmed. The MPC% and T g of the copolymers were better than the control. PD-CMA at 20 wt. % in the P (B-Co-CMA) copolymer exhibited the highest MPC% and Tg. CONCLUSION: The incorporation of PD-CMA in the composite resin resulted in new P (BD-Co-CMA) and P (B-Co-CMA) copolymers with improved MPC% and Tg. CLINICAL SIGNIFICANCE: The substitution with PD-CMA offset the shortcomings of the conventional BD comonomers concerning the mechanical properties and biocompatibility of the restorative composite resin. This might ameliorate the restorations in vivo longevity and serviceability.

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BACKGROUND: Polymerization shrinkage is an innate characteristic of thermo-polymerized denture base acrylic resin. Volumetric shrinkage is still a problem, although myriad material modifications. Ring-opening oxaspiro monomers have promising volumetric expansions of about 7%. These monomers have diminished the shrinkage in dental filling resins through copolymerization (CP). However, their CP with denture base resins is not reported yet. PURPOSE: The aim is to confirm the CP of an oxaspiro monomer with methyl methacrylate (MMA) by radical-cationic hybrid polymerization and to assess the degree of conversion (DC) of the formed copolymer. MATERIALS AND METHODS: The oxaspiro monomer was synthesized by a transesterification reaction. The study groups were based on the composition and thermo-polymerization method. The control and E1 groups were thermo-polymerized in water-bath, whereas the E2 group in a laboratory autoclave. Both E1 and E2 groups contained the oxaspiro monomer and cationic initiator. E2 group had an additional radical initiator. The CP and DC were confirmed and assessed by infrared spectroscopy. RESULTS: Accentuation of carbonyl peak, the disappearance of the spiro-carbon peak, and the appearance of ether linkages in experimental groups confirmed the ring-opening. E2 group had the highest DC. CONCLUSION: The oxaspiro monomer successfully copolymerized with MMA and had good DC.

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BACKGROUND: Polymethyl methacrylate (PMMA) is a widely used resin in the field of prosthodontics for fabricating myriad orofacial prostheses. Albeit several advantages, it possesses certain lacunae concerning physicomechanical properties. PURPOSE: This in vitro research aimed to evaluate the surface roughness (SR) and hardness (SH) of heat-cured PMMA processed with a cycloaliphatic monomer, tricyclodecane dimethanol diacrylate (TCDDMDA), in methyl methacrylate at various concentrations. MATERIALS AND METHODS: Groups have been divided into control (SRC and SHC) and experimental groups (SR10 and 20; SH10 and 20). Forty-five PMMA disc specimens were prepared. SR was assessed using a nanomechanical testing machine and the arithmetic roughness (Ra) was recorded. The same specimens were then subjected to Vicker's microhardness testing and Vicker's hardness number (VHN) was obtained. Data were compared using one-way analysis of variance (ANOVA) and post hoc Bonferroni tests (α=0.05). RESULTS: The mean (standard deviation [SD]) of SRC, SR10, and 20 groups were 111.415 nm (0.789), 62.666 nm (0.482), and 41.004 nm (0.561), respectively. The mean (SD) VHN of SHC, SH10, and 20 groups were 21.003 (0.252), 23.975 (0.207), and 34.622 (0.079), respectively. CONCLUSION: The addition of TCDDMDA markedly decreased the SR and increased the SH of the experimental groups.

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AIM: The aim of this study is to evaluate cytotoxicity of tricyclodecane dimethanol diacrylate (TCDDMDA) when added to conventional heat-cure methyl methacrylate (MMA) monomer at 10% and 20% (v/v) concentrations. MATERIALS AND METHODS: Twenty seven disk-shaped processed specimens were divided into control group (n = 9; comprises specimens made without substituting TCDDMDA in MMA) and two experimental groups (n = 9 each; specimens prepared by substituting TCDDMDA in MMA at 10% and 20% (v/v) concentration). Eluates were prepared by placing three specimens of each group into 9 mL of culture medium and then incubated at 37ºC for 24 hours. Continuous cells lines of L929 mouse fibroblast cells were used and MTT assay was employed to assess cytotoxicity. One-way analysis of variance (ANOVA) with post hoc Tukey's honestly significant difference (HSD) test was used to compare the mean optical density (OD) values and cell viability among the groups. RESULTS: A statistically significant difference was obtained (p = 0.000) when the mean and standard deviation of OD and cell viability (%) of the groups were compared. Highest OD value and cell viability was obtained with E20 group followed by E10 group. CONCLUSION: Addition of TCDDMDA in MMA of heat-cure denture base resin has no cytotoxic effect on L929 mouse fibroblasts. CLINICAL SIGNIFICANCE: Dual-reactive TCDDMDA is a crosslinking monomer which has no cytotoxic effects on mammalian cell cultures. Hence, incorporation of TCDDMDA to MMA can be extrapolated and projected for fabricating dentures without compromising biocompatibility. How to cite this article: Ranganthan A, Karthigeyan S, Murugesan SV, et al. Evaluation of In Vitro Cytotoxicity of Heat-cure Denture Base Resin Processed with a Dual-reactive Cycloaliphatic Monomer. J Contemp Dent Pract 2019;20(11):1279-1285.

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