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

Histocompatibility of Dental Restorative Composite Resin Photopolymerized with a Novel Multifunctional Comonomer: A Histopathological Analysis in Rats

BACKGROUND

Restorative dentistry is impossible without composite resins. Toxicity of these resins is common though possessing favorable properties. Modifications of the resin matrix are being executed to improve the properties of the material. Dipentaerythritol penta-/hexa-acrylate (DPEPHA) monomer has been recently identified as a cross-linking comonomer with the conventional resin matrix.

PURPOSE

This study aimed to investigate the histocompatibility of DPEPHA comonomer in photopolymerized resin at 20 and 40 wt.% concentrations in rats.

MATERIALS AND METHODS

Eighteen male Wister rats were subjected to subcutaneous implantation of conventional resin specimens without DPEPHA (G0) and with DPEPHA at 20 wt.% (G20) and 40 wt.% (G40) concentrations. Then, the rats were subdivided according to the time of resection of the implantation sites at 1, 2, and 4 weeks (n = 6 rats). Tissue specimens were submitted to histopathological analysis.

RESULTS

Except for 4 weeks' time interval, there were significant differences (P < 0.05) in the inflammation among the groups at each time interval. The order of inflammation was NC <G40 ≤G20 <G0. Concerning the fibrous capsule thickness, significant difference existed among the groups at each time interval and within the groups at all 3 time intervals (P < 0.05).

CONCLUSION

Composite resin specimens with DPEPHA comonomer exhibited good histocompatibility in rats at 40 wt.% concentration.

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.