Mechanical Characteristics of (TiO2-ZnO)/PMMA Nanocomposites for Dentures

Mechanical properties (impact strength, compressive strength and flexural strength) have been studied for (Polymethyl-methacrylate (PMMA)) polymer reinforced with nano (TiO2+ZnO) (0 v%, 1 v%, 2 v%, 3 v%, 4 v% and 5 v%). Ultrasonic dispersion technique was used to prepare the nanocomposites samples, follow with cold casting technique using Teflon molds standard conditions. Charpy impact instrument was used to measure the impact strength, the compressive strength of each sample which was tested in newton units using digital compression tester (TinusOlsen: H50KT, England), while flexural strength can be found from mathematical formulas which depend on the impact strength, compressive strength and flexural strength. Results show that values increase in 1 v%, then decrease alternately by (2 v%, 3 v%, 4 v%, and 5 v%), while 0 v% is the less value of volume fraction of fillers. Young modules values increase alternately by the volume fraction of fillers until 2 v%, while if it is higher and lower than 2 v% it decreases the modulus of elasticity.

Clinical Effects and Radiological Results of Vertebroplasty: Over a 2-year Follow-Up Period

OBJECTIVE: We investigated the association between clinical and radiological results and assessed the radiological changes according to the distribution pattern and amount of injected cement after vertebroplasty. METHODS: Two hundred and one patients underwent vertebroplasty; of these, 15 were follow up for more than 2 years. For radiological analysis, we grouped the patients according to cement distribution as follows: group 1, unilateral, unilateral distribution of cement; group 2, bilateral-uneven, bilateral distribution of cement but separated mass; and group 3, bilateral-even, bilateral single mass of cement. To compare radiologic with clinical results, we assessed the visual analogue scale (VAS) score, amount of injected cement, bone mineral density (BMD), postoperative and follow-up vertebral body compression ratios, and postoperative and follow-up kyphotic angles. RESULTS: There were 4 (26.7%) patients in group 1, 6 (40.0%) in group 2, and 5 (33.3%) in group 3. The mean VAS score was 5.2 preoperatively, 1.8 postoperatively, and 3.2 at 2-year follow-up. The 2-year follow-up compression ratio was better in patients with even distribution of injected cement (group 2 and 3) than group 1. However, it was not statistically insignificant (p>0.05). The follow-up kyphotic angle was more aggravated in the group 1 than in the other groups (p<0.05). CONCLUSION: Our study showed that vertebroplasty had a beneficial effect on pain relief, particularly in the immediate postoperative stage. The augmented spine tended to be more stable in the cases with increased amount and more even distribution of injected cement.