Effect of disinfection techniques on physical-mechanical properties of a microwave-activated acrylic resin

Effects of disinfectants on physical properties of denture base resins: A systematic review and meta-analysis

STATEMENT OF PROBLEM

The disinfection of removable dental prostheses and orthodontic appliances is essential to preventing transmission of pathogens. However, whether different disinfection solutions and durations affect the physical properties of denture base resins is unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to statistically analyze the influence of disinfectants on the physical properties of denture base resins.

MATERIAL AND METHODS

A systematic search in Medline, Embase, PubMed, and Cochrane Library databases was conducted to evaluate the effects of chemical disinfection on the physical properties of denture base resins such as surface morphology, roughness, hardness, and flexural strength. Of 1909 studies, 44 studies were included in the systematic review and 41 in the meta-analysis. Heterogeneity was analyzed by using I2 statistics. The influence of different disinfection solutions and durations on the physical properties was further analyzed, and the risk of bias evaluated. Statistical analyses were performed by using the RevMan 5.4 software program with the standardized mean differences (SMDs) and 95% confidence intervals (CIs).

RESULTS

Of the 44 included studies, 40 studies were assessed as having a low risk of bias, and 4 had an unclear risk of bias. Meta-analysis results showed that compared with the control, disinfection could not significantly affect surface roughness and hardness within 60 minutes of immersion in disinfectant solutions or flexural strength within 30 minutes (roughness: P=.79, I2=0%; flexural strength: P=.08, I2=0%; hardness: P=.05, I2=19%). In addition, the physical properties were not significantly affected when glutaraldehyde, chlorhexidine, and peracetic acid were repeatedly used for more than 30 minutes.

CONCLUSIONS

Most of the disinfectants did not reduce the physical properties of denture base resin within 30 minutes of immersion. Glutaraldehyde, chlorhexidine, and peracetic acid are recommended if longer immersion or repeated disinfection is required.

A simple and low-cost technic for immobilization of mandible during head and heck radiotherapy: a technical note

Immobilization protocols for head and neck radiotherapy (HNR) are needed to reduce radiation dispersion in non-tumoral tissues and to reduce damage to noble structures; however, involuntary mandibular movements require additional adaptations of thermoplastic masks.

PURPOSE

Our objective was to describe an easy and low-cost disposition to help thermoplastic masks immobilize the mandible during HNR.

MATERIALS AND METHODS

We created Styrofoam models to stabilize the mandible which was used to make adaptation to the thermoplastic masks. The Styrofoam model was inserted into alginate to construct a mold and a self-curing acrylic resin was added into the mold. After the acrylic resin hardened, the dispositive mandibular immobilizer was removed from the alginate mold and adjusted with Maxicut and Minicut or other drills and sandpaper. The alginate mold can be used on the same day to create backup devices.

RESULTS AND CONCLUSIONS

Our device was made in a simple way, has a low cost, and helps the thermoplastic masks to immobilize the mandible, leading to a more precise individualization of head and neck immobilization that can reduce unanticipated radiation scatter and improve radiation distribution.

Synergistic impact of cellulose nanocrystals with multiple resins on thermal and mechanical behavior

The cellulose nanocrystals (CNCs) surface modified with phenolic and acrylic resins were investigated for different properties such as thermally stability and adhesive property, the mechanical properties of CNCs and interactions of the resulting materials at a micro-level are very important. Phenolic resins are of great interest due to their smooth structure, low thermal conductivity and good thermal insulation. However, the high spray rates and poor mechanical properties limit its use for external insulation of buildings. Acrylic resins are used as a matrix resin for adhesives and composites due to their adhesion, mechanical properties, and their good chemical resistance. The brittleness of acrylic resins makes them less attractive than the structural materials, being much harder. For this reason, most of the resins are modified with suitable elastomers, which act as hardeners. Therefore, treatment of these compounds is necessary. In this research paper, the effect of CNCs surface on phenolic and acrylic resins were investigated to obtain an optimized surface using three different weight (wt%) ratios of CNCs. Scanning electronic microscopy (SEM), X-rays diffraction (XRD), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the structure, and investigate different properties of CNCs. Furthermore, the Zwick/Roell Z020 model was used to investigate the adhesion properties of the phenolic and acrylic resins with CNCs.