Formulation, Configuration, and Physical Properties of Dental Composite Resin Containing a Novel 2π + 2π Photodimerized Crosslinker - Cinnamyl Methacrylate: An In Vitro Research.

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.

Antimicrobial Efficacy of Irreversible Hydrocolloid Impression Impregnated with Silver Nanoparticles Compared to Surface Disinfected Impressions - An In vivo Study.

BACKGROUND: Routine disinfection procedures have shown to cause incomplete disinfection and detrimental effects on dimensional properties of the impression. Hence, self-disinfecting impression materials impregnated with antimicrobial agents were developed. PURPOSE: The purpose is to evaluate the antimicrobial efficacy of silver nanoparticles (AgNPs) impregnated in irreversible hydrocolloid (IH) impression material in in vivo conditions. MATERIALS AND METHODS: This study comprised of four groups-IH impressions disinfected by immersion in 2% glutaraldehyde, IH impregnated with AgNPs of sizes 80-100 nm and 20-30 nm, nondisinfected impressions as control. Five impressions were made for each group and a total of 20 impression samples were made. The antimicrobial action of each sample was assessed by counting the number of colony forming units and by disc diffusion method. RESULTS: The results were obtained and the data were statistically analyzed by Kruskal-Wallis test and tabulated. The results revealed that AgNPs of size 80-100 nm when impregnated in irreversible impression material showed effective antimicrobial action. CONCLUSION: The anti-microbial action of 80-100 nm AgNP impregnated IH impressions is comparable to that of impressions disinfected by immersion in 2% glutaraldehyde for 10 min.

Effect of Novel Cycloaliphatic Comonomer Incorporation on the Color Stability of Thermo-polymerized Denture Base Resin.

BACKGROUND: Denture during its in vivo service encounters myriad food pigments and numerous physico-mechanical dynamic changes. Denture discoloration is one of the unresolved problems that should be unraveled to satisfy the esthetic demands of the patients. AIM: This study aims to evaluate the color stability of a novel denture base copolymer with 10% and 20% (vol/vol) concentration of cycloaliphatic comonomer. MATERIALS AND METHODS: Control group (G0) comprises specimens made without cycloaliphatic comonomer. The specimens of trial groups G10 and G20 were fabricated with 10% and 20% cycloaliphatic comonomer, respectively. For each group, thirty specimens (n = 30) were made. The specimens (n = 10) were immersed in three food colorant solutions (erythrosine, tartrazine, sunset yellow) for 56 days after artificial thermal aging. Ultraviolet-visible spectrophotometer was employed to measure the tristimulus values and calculate the color change (ΔE) of the specimens prior to and following rapid thermal aging or immersion of the specimens in the food colorants. RESULTS: G0 showed the highest ΔE and G20 exhibited the least with each colorant. G10 had an intermediate imperceptible ΔE with each colorant. Also, significant differences (P = .000) existed between the food colorants within each group. The highest ΔE value was observed with sunset yellow and the lowest ΔE with tartrazine with each group. CONCLUSION: The addition of cycloaliphatic comonomer in denture base acrylic resins improved the color stability. The new copolymer with 20 Vol.% comonomer exhibited the highest color stability with all the food colorants.

Bond Strength of Acrylic Denture Tooth to a Novel Thermo-Polymerized Denture Base Copolymer Containing Cycloaliphatic Comonomer after Mechanical and Thermal Aging.

BACKGROUND: There are numerous artificial denture tooth materials available of which acrylic resin teeth were used widely. The resin teeth bond chemically to the denture base resin, and this bonding is affected by numerous intrinsic and extrinsic factors. The type of cross-linker in the denture base monomer is one such factor which has a questionable influence on the bond strength. Recently, cycloaliphatic comonomer was added in the methyl methacrylate monomer and the resultant novel copolymer possessed good physico-mechanical and biological properties. PURPOSE: The purpose of this study was to evaluate the shear bond strength (SBS) between acrylic denture tooth and resultant novel copolymer after cyclic loading and thermal aging. MATERIALS AND METHODS: Sixty central incisor denture teeth were bonded to three types of acrylic denture base resin groups (n = 20 per group) categorized based on the presence of the cycloaliphatic comonomer - Control group (G0): denture bases without cycloaliphatic comonomer and trial groups G10 and G20 contain 10 vol.% and 20 vol.% comonomer, respectively, substituted in the denture base monomer component. The specimens were processed and subjected to cyclic loading and thermal aging which was then followed by SBS testing. RESULTS: G20 possessed the highest SBS followed by G10. G0 had the least SBS. All the specimens of the control and trial groups exhibited adhesive-cohesive mixed failure at the resin tooth-base resin interface. CONCLUSION: The addition of cycloaliphatic comonomer increased the SBS between the resultant novel copolymer and the resin teeth after cyclic loading and thermal aging.

Effect of Novel Cycloaliphatic Comonomer on Surface Roughness and Surface Hardness of Heat-cure Denture Base Resin.

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.

Histocompatibility of Novel Cycloaliphatic Comonomer in Heat-cured Denture Base Acrylic Resin: Histomorphometric Analysis in Rats.

BACKGROUND: Prosthodontics is impossible without denture base resins. Allergic reactions to these resins are not uncommon, albeit favorable properties. Monomeric modifications are being done to improve the properties of the material. Tricyclodecane dimethanol diacrylate (TCDDMDA) monomer has been recently identified and experimented as a comonomer with methyl methacrylate (MMA). AIM: This study aimed to investigate the histocompatibility of TCDDMDA comonomer in polymerized resin at 10% and 20% (vol/vol) concentrations in rats by histomorphometric analysis. MATERIALS AND METHODS: Twenty-four male Wistar rats were randomly divided into the following four groups: NP group (control; n = 6), with no palatal appliance, Groups P0, P10, and P20 were fixed with palatal appliances fabricated of 100% MMA, 10% TCDDMDA + 90% MMA, and 20% TCDDMDA + 80% MMA, respectively. Weights of the animals were recorded just before the appliance placement and after 14 days. The animals were sacrificed, and the palatal tissues were processed for histopathological analysis. Histomorphometric parameters assessed were total epithelial (ET), connective tissue (CT), and keratin layer (KT) thicknesses. RESULTS: No significant difference was observed regarding body weight. Group P0 showed increased ET, CT, and KT when compared to other groups. Bonferroni multiple comparison tests showed a statistically significant difference between all the groups except between P10 and P20 for all the three morphometric parameters. CONCLUSION: Palatal appliances with TCDDMDA comonomer showed good histocompatibility in rats up to 20% (vol/vol) concentration.

Chemical Structure and Physical Properties of Heat-cured Poly(methyl methacrylate) Resin Processed with Cycloaliphatic Comonomer: An In Vitro Study.

AIM: The purpose of this in vitro research is to chemically characterize polymethyl methacrylate (PMMA) processed with 10% and 20% (v/v) tricyclodecane dimethanol diacrylate (TCDDMDA) comonomer. It also aimed to assess the degree of conversion (DC) and glass transition temperature (Tg) of the formed copolymers. MATERIALS AND METHODS: The experimental groups were processed with the TCDDMDA comonomer (10% and 20% v/v), whereas the control group was processed only with the methyl methacrylate monomer. The copolymerization was studied by nuclear magnetic resonance (NMR) spectroscopy. The surface characteristics and composition (wt%) were studied by field-emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy (cuboidal specimen; 5 mm × 5 mm × 3 mm), respectively. The DC and Tg of the formed copolymers (powdered form) were analyzed by Fourier transform infrared spectroscopy and differential scanning calorimetry, respectively. One-way analysis of variance with post hoc Bonferroni test was used to compare the mean values of DC% and Tg among the groups. RESULTS: The newly formed copolymer [P(MMA-co-TCDDMDA)] was chemically characterized by NMR and FESEM-EDX. The DC and Tg of the experimental groups were higher than the control. Tricyclodecane dimethanol diacrylate at 20% (v/v) concentration showed the highest DC and Tg. CONCLUSION: The addition of TCDDMDA comonomer improved the DC and Tg of the formed copolymer. CLINICAL SIGNIFICANCE: The P(MMA-co-TCDDMDA) copolymer is expected to improve the mechanical properties and biocompatibility of the denture base acrylic resin. This would result in improved denture quality and durability, thereby, imparting a better quality of life to the geriatric population.

Chemical Characterization of Denture Base Resin with a Novel Cycloaliphatic Monomer.

AIM: The aim of this study is to identify and characterize newly formed copolymers by modifying methyl methacrylate (MMA) monomer by substituting cycloaliphatic monomer using Fourier transform infra-red (FTIR) spectroscopy. MATERIALS AND METHODS: Heat-cure polymethyl methacrylate (HC-PMMA) experimental specimens were made by dissolving tricyclodecane dimethanol diacrylate (TCDDMDA) at 10% and 20% concentrations in commercially available MMA monomer. Specimens made without TCDDMDA served as the control. The specimen was then scrapped and mixed with dried potassium bromide (KBr) to form pellet. Each pellet was placed in a FTIR spectrometer and 10 scans were recorded with a spectral resolution of 4 cm-1. A mean of scans was automatically processed and deduced by the system software and a final transmittance spectral graph was obtained for one specimen. RESULTS: Three significant spectral differences exist between control and experimental groups. The first difference was the disappearance of weak peak at 1637.34 cm-1 (alkenyl C═C stretch) in both experimental groups. The second difference was the appearance of new moderate broad peaks at 1482.25 cm-1 and 1449.56 cm-1 in both experimental groups which are attributed to the ring -CH2 asymmetric bending (C-H deformation) vibrations. The third difference was the appearance of another new weak peak at 1386.57 cm-1 in both experimental groups. This new peak confirms the formation of a new structure of copolymer. CONCLUSION: TCDDMDA copolymerizes with MMA, thereby decreasing the uncured residual monomer in the polymerized specimens. CLINICAL SIGNIFICANCE: Copolymerization of TCDDMDA with MMA would lead to the development of new monomeric composition for the fabrication of dentures possessing better mechanical properties and biocompatibility.

Evaluation of In Vitro Cytotoxicity of Heat-cure Denture Base Resin Processed with a Dual-reactive Cycloaliphatic Monomer.

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.