Dynamic Mechanical Thermal Analysis of Maxillofacial Prosthetic Elastomers

Abstract

In this study, dynamic mechanical thermal analysis was used to evaluate the changes that occurred in maxillofacial elastomers subjected to different disinfecting regimens. A commercial polydimethyl siloxane (PDMS) and an experimental chlorinated polyethylene (CPE) were treated with different disinfection procedures for a period that simulates 1 year of clinical service: microwave exposure (D1), hypochlorite solution (D2), neutral soap (D3), and a commercial disinfecting solution (D4). A fifth group was kept in dark storage as control. Dynamic mechanical thermal analysis tests operated in a fixed frequency (1 Hz) over a range of temperatures (-130°C to 20°C for PDMS, -60°C to 120°C for CPE). Loss modulus (G″), storage modulus (G'), and loss factor (tanδ) were recorded as a function of temperature. The obtained glass transition temperature (Tg) values were subjected to statistical analysis. Dynamic mechanical thermal analysis revealed changes in Tg values for both materials, which reflect the possible changes in their chemical and physical structure, after different disinfection procedures. The PDMS and CPE samples seem to have less dense structure maybe because of chain scission reaction that probably occurred during the disinfection procedures. According to statistical analysis, Tg values presented significant changes from the control samples among the different materials and disinfecting procedures. Microwave exposure and hypochlorite solution affect CPE significantly, whereas PDMS exhibited significant changes after being treated with a commercial antimicrobial agent, concerning changes that occurred in Tg. In all cases, Tg values were decreased compared with the untreated samples, which were stiffer, presenting higher Tg and G' values.

Antimicrobial activity of conventional and plant-extract disinfectant solutions on microbial biofilms on a maxillofacial polymer surface

“…The activity of the mitochondrial dehydrogenase reduces the XTT tetrazolium salt to formazan salt, resulting in a colorimetric change correlating with the cell viability. 29 An XTT salt solution (Sigma-Aldrich) was prepared in ultrapure water at a final concentration of 1 mg/mL, and menadione solution (0.4 mM in acetone; Sigma-Aldrich) was prepared immediately before each assay. The disinfection solutions were added to each well of a microtiter plate containing 1 silicone specimen to be tested for 10 minutes.…”

“…17,19,20 Chemical disinfection using nonirritating disinfectant solutions ensures the health of tissues that come into contact with prostheses because, when properly cleaned, the risk of infection is minimized. [13][14][15][16] Conventional cleaning protocols involve mechanical biofilm removal (with manual toothbrushing or washing by hand with water and neutral soap), [21][22][23][24][25] effervescent solutions such as cleansing tablets, [22][23][24][25] sodium hypochlorite 0.5% to 1%, [26][27][28][29] and chlorhexidine 2% to 4%. 13,[22][23][24][30][31][32][33] However, frequent exposure to these solutions may interfere with the properties of silicone.…”

“…13,[22][23][24][30][31][32][33] However, frequent exposure to these solutions may interfere with the properties of silicone. [22][23][24][25][27][28][29]31,33,34 Thus, research is necessary to find alternative methods of disinfection using solutions that do not alter the silicone surface and that are harmless to individuals. 35 Given the paucity of studies in dentistry on this issue, phytotherapy seems to be one possible option, as it is inexpensive and easy to use.…”

Assessment of treatment outcomes for facial prostheses in patients with craniofacial defects: A pilot retrospective study

“…15,16 Also, some investigations suggest that digital friction induces the detachment of the additives that are incorporated into the elastomer matrix, even when it is performed gently; unfortunately, hygiene procedures for facial prostheses are mandatory, so this cannot be avoided. [18][19][20] This factor might also explain the excessive number of small repairs (retouches) that were observed in nearly all patients. Figure 1 shows that most of the prostheses failed 1 to 3 years after clinical installation, indicating that the mean life span of the prostheses is similar to the values previously reported by other clinical studies.…”

“…1,[13][14][15][16] However, the most common reason for the replacement of facial prostheses is the impairment of the properties of silicone elastomers, which is generally identified by the discoloration or failure of the material. 6,[13][14][15][16][17][18][19][20][21][22] This deterioration is caused primarily by exposure to weather conditions, human body secretions, and prosthesis maintenance procedures. 1,6,12,23 Some studies have reported that the mean life span of a silicone-based facial prosthesis ranges from between 1.5 and 3 years, with only a small percentage of prostheses (4.8%) lasting longer than 2 years.…”