The influence of reaction rate on the evolving polymer structure of photo-activated dimethacrylate biomedical resins was investigated using neutron and in situ synchrotron X-ray scattering with simultaneous Fourier-transform-near-infrared spectroscopy. Previous studies have correlated the degree of reactive group conversion with mechanical properties, but the impact of polymerization rate on the resultant polymer structure is unknown. Here, we demonstrate that the medium-range structural order at the functional end groups of these materials is dependent on the reaction rate. Accelerating polymerization increases correlation lengths in the methacrylate end groups but reduces the medium-range structural order per converted vinyl bond when compared with more slowly polymerized systems. At faster rates of polymerization, the conformation of atoms at the reacting end group can become fixed into the polymer structure at the onset of autodeceleration, storing residual strain. Neutron scattering confirms that the structural differences observed are reproduced at longer length scales. This effect is not as prominent in systems polymerized at slower rates despite similar final degrees of reactive group conversion. Results suggest that current interpretations of these materials, which extrapolate mechanical properties from conversion, may be incomplete. Accelerating polymerization can introduce structural differences, which will dictate residual strain and may ultimately explain the discrepancies in the predictive modeling of the mechanical behavior of these materials using conventional techniques.
This study highlights the variability in the approach of clinicians in dental and oral rehabilitation of patients undergoing radiotherapy treatment for oral cancer patients.
BackgroundPeriodontal disease is a common chronic inflammatory disease that has been associated with rheumatoid arthritis and a potential causal role has been suggested. However, data on the prevalence of periodontal disease in patients with systemic lupus erythematosus (SLE) are scarce.ObjectivesTo investigate the prevalence of periodontal disease in patients with systemic lupus erythematosus and compare it to that of the general population.MethodsWe examined the periodontal status in dentate patients with SLE who met the ACR criteria for SLE. Mild periodontitis was defined as having at least one periodontal probing depth of 4+mm. Severe periodontitis was defined as having at least one periodontal probing depth of 6+mm. We compared the prevalence of periodontal disease in SLE patients with that of a geographically matched dentate sub-sample of the Adult Dental Health Survey (ADHS), West Midlands, a representative population survey in the UK (reference group). Age-standardized prevalence estimates were calculated and logistic regression was used to evaluate the association between SLE and periodontal disease adjusting for age and sex.ResultsWe examined a total of 105 individuals with SLE, with a mean age of 45.6 years (IQR 36-56), of whom 98 (92%) were women. The reference group included 484 participants, with a mean age of 48.9 years (IQR 36-63), of whom 271 (56%) were women. The age-standardised prevalence of periodontitis was 85% (95% CI: 79% to 92%) in SLE patients, compared with 55% (95% CI: 51% to 60%) in the general West Midlands population. After adjustments for age and sex, patients with SLE were significantly more likely to have periodontitis than ADHS participants (OR 7.25, 95% CI 3.84 to 13.68). Results were similar when analyses were restricted to women only (OR 7.51, 95% CI: 3.85 to 14.64). The age-standardised prevalence of severe periodontitis was 11% (95% CI: 5% to 18%) in patients with SLE and 11% (95% CI: 8% to 14%) in the West Midlands population. No significant association of SLE with severe periodontitis was observed (OR 1.15, 95% CI: 0.56 to 2.36).ConclusionsOur data suggests that periodontal disease is more common among individuals with SLE compared to a representative geographically matched sample. However, the prevalence of severe periodontal disease is similar between SLE and the general population. Further studies are necessary to confirm the possible association between periodontitis and SLE.Disclosure of InterestNone declared
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