PubMed · 294376
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P U Gennari. 1979. [Occlusal plates and splints].. https://pubmed.ncbi.nlm.nih.gov/294376/
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Previous work reported that commercial dental composite resins containing a urethane-modified bisGMA (bisphenylglycidyl dimethacrylate)/TEGDMA (triethylene glycol dimethacrylate) (ubis) based monomer system showed a 10-fold reduction in the release of a bisGMA-derived product, bishydroxypropoxyphenyl propane (bisHPPP), as compared with that found for bisGMA/TEGDMA (bis) based composites after incubation with cholesterol esterase (CE). Unfortunately, these materials also differed substantially in filler type and content, making it impossible to directly relate any specific parameter to the differences in biodegradation levels. By controlling for filler content and type, the current study will seek to probe the biomolecular interactions between composite resin chemistry and esterase activity in order to help explain the observed differences in biodegradation levels between the ubis and bis resin systems. After 32 days of incubation, buffer and CE solutions were analyzed for degradation products using high-performance liquid chromatography, UV spectroscopy, and mass spectrometry. Both materials were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. In the CE groups, the ubis system showed a 2.6- to 86-fold reduction (dependent on the product) in the amount of isolated products relative to the bis system (p < 0.01). Scanning electron microscopy data also demonstrated the relative stability of the ubis system and X-ray photoelectron spectroscopy analysis showed a higher content of the ester bond at the surface of the bis samples. Fourier transform infrared data showed that both resins had similar conversions. Because both systems were identical except for their monomer systems, it was concluded that changes in biostability were associated with chemistry. Crosslinking, hydrophobicity, and solubility all relate to ubis's pro-stability.
OBJECTIVE: Dental treatment involves the use of a wide range of materials. Many of the dental materials or their components pose a potential risk to the patient and member of the dental team. Pre-market biocompatibility testing cannot guarantee absolute safety, making monitoring of materials likely to cause an adverse reaction essential. The prevalence of adverse reactions to dental materials amongst dental patients and staff has not been systematically monitored in the UK. This project aims to develop a systematic approach to the evaluation and monitoring of the extent and severity of adverse reactions to dental materials in the UK. METHOD: Through the distribution of reporting forms to dental surgeries and laboratories in the UK, the ARRP has received 1,075 complete reports relating to adverse reactions seen or experienced by dental staff and patients. RESULTS: The main findings were that different materials cause adverse reactions to different groups of people. The largest proportion of patient related adverse reactions were reported to be due to metals (n = 175). These were mainly amalgam associated oral lichenoid reactions (n = 124). Dental technicians reported acrylic resin as the causal factor of hand dermatitis in 61% (44 out of a total 72) of cases reported. Finally, dental surgery staff reported gloves as causing hand dermatitis in 75% of cases (398 out of a total 531). CONCLUSIONS: Different dental materials affect different person groups depending on their exposure to the material. Dental staff are most at risk from an adverse reaction to latex gloves, whereas most reported reactions for patients were due to metals. For dental technicians the biggest danger of an adverse reaction was from acrylic resins. There is a need to continue to raise the awareness among dental professionals of the existence of the Adverse Reactions Reporting Project so as to overcome problems of under-reporting.
Sequential interpenetrating network (IPN) of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) were prepared and crosslinked with glutaraldehyde (GA) to form pH-sensitive microspheres by the water-in-oil (w/o) emulsification method. Microspheres were used to deliver a model anti-inflammatory drug, diclofenac sodium (DS), to the intestine. The formed IPN was analyzed by Fourier transform infrared spectroscopy (FTIR). Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses were done on the drug-loaded microspheres to confirm the polymorphism of DS. Results indicated a molecular level dispersion of DS in the IPN. Microspheres formed were spherical with the smooth surfaces as evidenced by scanning electron microscopy (SEM). Particle size and size distribution was studied using laser light diffraction particle size analyzer. Particle size analysis was also done by optical microscope for the selected microspheres; the change in diameter of the microspheres when soaked in different media at different time intervals was measured by optical microscope. Microspheres showed a pulsatile swelling behavior when the pH of the swelling media was changed. The swelling data were fitted to an empirical equation to understand the phenomenon of water transport as well as to calculate the diffusion coefficient (D). Values of D in acidic media were lower than those found in basic media. The values of D decrease with increasing crosslinking of the matrix. In-vitro release studies have been performed in 1.2 and 7.4 pH media to simulate gastric and intestinal conditions. The results indicated a dependence on the pH of the release media, extent of crosslinking and the amount of drug loading.