PURPOSE: The aim of this study was to appraise the some mechanical properties of polymethyl methacrylate based denture base resin polymerized by copolymerization mechanism, and to investigate the cytotoxic effect of these copolymer resins. MATERIALS AND METHODS: 2-hydroxyethyl methacrylate (HEMA) and isobutyl methacrylate (IBMA) were added to monomers of conventional heat polymerized and injection-molded poly methyl methacrylate (PMMA) resin contents of 2%, 3%, and 5% by volume and polymerization was carried out. Three-point bending test was performed to detect flexural strength and the elasticity modulus of the resins. To determine the statistical differences between the study groups, the Kruskall-Wallis test was performed. Then pairwise comparisons were performed between significant groups by Mann-Whitney U test. Agar-overlay test was performed to determine cytotoxic effect of copolymer resins. Chemical analysis was determined by FTIR spectrum. RESULTS: Synthesis of the copolymer was approved by FTIR spectroscopy. Within the conventional heat-polymerized group maximum transverse strength had been seen in the HEMA 2% concentration; however, when the concentration ratio increased, the strength decreased. In the injection-molded group, maximum transverse strength had been seen in the IBMA 2% concentration; also as the concentration ratio increased, the strength decreased. Only IBMA showed no cytotoxic effect at low concentrations when both two polymerization methods applied while HEMA showed cytotoxic effect in the injection-molded resins. CONCLUSION: Within the limitations of this study, it may be concluded that IBMA and HEMA may be used in low concentration and at high temperature to obtain non-cytotoxic and durable copolymer structure.
Denture Bases ; Elastic Modulus ; Hot Temperature ; Polymerization* ; Polymers* ; Polymethyl Methacrylate ; Spectroscopy, Fourier Transform Infrared ; Spectrum Analysis

INTRODUCTIONThe hippocampus is an important region of the brain that regulates cognitive and emotional functions. In this study, we examined the impact of perinatal administration of testosterone propionate (TP) on the number of pyramidal neurons in the CA1 and CA3 regions of the hippocampi of female rats.

METHODSFive groups of rats were used in this study. Three groups of female rats were administered TP in either both the prenatal and the postnatal periods (Group 1), only the prenatal period (Group 2) or only the postnatal period (Group 3). The other two groups of rats included control females (Group 4) and control males (Group 5). The rats were sacrificed on postnatal Day 120 and their brains were analysed for hippocampal pyramidal neuron number using stereological methods.

RESULTSControl male rats (Group 5; p = 0.043) and TP-treated female rats in Groups 1 (p = 0.012) and 2 (p = 0.037), but not Group 3 (p > 0.05), had a significantly higher number of pyramidal neurons than control female rats (Group 4). The rats in Group 1 had the highest number of pyramidal neurons among the female rats.

CONCLUSIONPerinatal TP treatment has an augmenting effect on the number of pyramidal neurons in the hippocampi of female rats. We also found gender-based differences in the hippocampi of male and female rats, with a higher number of pyramidal neurons seen in male rats. Continuous TP administration during the prenatal and postnatal periods is more effective than administration only in the prenatal or postnatal period.

Animals ; Body Weight ; Female ; Hippocampus ; cytology ; drug effects ; Male ; Maternal Exposure ; Neurons ; drug effects ; Pregnancy ; Pregnancy, Animal ; Prenatal Exposure Delayed Effects ; Pyramidal Cells ; drug effects ; Rats ; Rats, Wistar ; Testosterone Propionate ; pharmacology

STUDY DESIGN: Retrospective. PURPOSE: This study investigated the possible association of persistent low back pain (LBP) with caesarean section (CS) under spinal anesthesia. OVERVIEW OF LITERATURE: Many women suffer from LBP after CS, which is commonly performed under spinal anesthesia. However, this type of LBP is poorly understood, and there is poor consensus regarding increased risk after spinal anesthesia. METHODS: We examined two groups of patients who underwent cesarean delivery under spinal anesthesia. Group I included patients who presented to a neurosurgical clinic complaining of LBP for at least 6 months. Group II was a control group with patients without LBP. We analyzed clinical and sagittal angle parameters, including age, body mass index, parity, central sagittal angle of the sacrum (CSAS), and sacral slope (SS). RESULTS: Fifty-three patients participated in this study: 23 (43.1%) in Group I and 30 (56.9%) in Group II. Non-parametric Mann–Whitney U-tests showed that age, parity, and CSAS significantly differed between the two groups at 6 months. CONCLUSIONS: Age, parity, and CSAS appear to be associated with increased risk for LBP after CS under spinal anesthesia. Future prospective studies on this subject may help validate our results.
Anesthesia, Spinal ; Body Mass Index ; Cesarean Section* ; Consensus ; Female ; Humans ; Low Back Pain* ; Parity ; Pregnancy ; Prospective Studies ; Retrospective Studies ; Risk Factors* ; Sacrum*