Effects of acid hydrolysis and mechanical polishing on surface residual stresses of low-fusing dental ceramics

STATEMENT OF PROBLEM: Cracks may arise in a ceramic restorative material over time, resulting in sudden fractures at stresses well below the yield stress. PURPOSE: This study evaluated by means of indentation technique the effects of acid hydrolysis and mechanical polishing on the surface residual stresses of low-fusing ceramic materials. MATERIAL AND METHODS: A total of 64 ceramic bars were formed to produce 4 groups of 16 bars each for 4 ceramic materials (Duceram-LFC Dentin, Duceram-LFC Enamel, Finesse Dentin, and Finesse Enamel). Four surface-treatment groups (n=4) were then formed for each of the 4 materials. The 4 surface treatments were control (autoglaze), hydrolysis, glaze/polish, and polish/glaze. A Vickers indenter contacted the Duceram-LFC specimens with a 5-N load and the Finesse specimens with a 3-N load for 10 seconds. Scanning electron microscope (SEM) was used to study surface texture before and after hydrolysis and polishing. Differences in mean crack lengths were analyzed with 1-way analysis of variance and least significant difference test (alpha=.05.) RESULTS: SEM showed obvious surface flaws as a result of hydrolysis on Duceram-LFC Enamel and Dentin specimens. However, statistical analysis of the resulting crack lengths revealed no significant differences between values for the control groups (58.16 +/- 3.88) (53.53 +/- 2.67) and hydrolysis groups (57.11 +/- 4.09) (54.54 +/- 3.15) for Enamel (P=.081) and Dentin (P=.093) respectively. When comparing polished groups and nonpolished groups, the mean crack lengths were significantly shorter for polished specimens of Duceram-LFC Enamel (53.76 +/- 3.17), Finesse Enamel (40.56 +/- 3.31), and Finesse Dentin (39.76 +/- 3.81) porcelains compared with their control groups (58.16 +/- 3.88) (43.54 +/- 4.12) (41.19 +/- 3.47), respectively (P<.0001). The mean crack lengths were significantly longer for polished specimens of Duceram-LFC Dentin (59.16 +/- 3.52) porcelain compared with the control group (53.53 +/- 2.67) (P<.0001). CONCLUSION: Within the limitations of this study, hydrolysis did not improve surface residual stresses of Duceram-LFC and Finesse ceramic materials. Mechanical polishing improved surface residual stresses of all materials tested, except Duceram-LFC Dentin porcelain.     

Atrioventricular Nodal Reentrant Tachycardia with Advanced Infra-Hisian Atrioventricular Block

We report a case of 78-year-old man admitted to the hospital due to palpitations and lightheadedness. On EKG advanced atrioventricular block with ventricular rate of 37 beats per minute was noted. On electrophysiology study a common type of atrioventricular nodal reentrant tachycardia was inducible with maintenance of advanced AV block. Radiofrequency ablation of slow pathway followed by placement of a permanent pacemaker resulted in elimination of tachycardia and resolution of symptoms.     

Ultrasonographic Prediction of Esophageal Varices in Schistosomiasis mansoni

Bleeding from esophageal varices is a common and serious problem in Schistosomiasis mansoni. A simple and accurate method of detection would facilitate measurement of individual and community morbidity and allow institution of preventive measures. An ultrasonographic scoring system grading periportal fibrosis, portal vein diameter, spleen size, and portasystemic anastomoses was evaluated as a predictor of esophageal varices and a past history of upper gastrointestinal hemorrhage in 43 patients with hepatosplenic schistosomiasis. Ultrasonographic variceal score correlated ( r = 0.86, p < 0.001) with the endoscopic variceal grade. Patients with a sonographic score of 5 or greater were highly likely (21 of 23) to have varices of grade II or greater (sensitivity, 91.3%; specificity, 94.7%). Only those with sonographic scores of 5 or greater (15 of 23) had bled from esophageal varices. The ultrasonographic score provided a simple, inexpensive, accurate, and noninvasive means of screening individuals with hepatosplenic schistosomiasis for esophageal varices, and correlated strongly with prior gastrointestinal hemorrhage. It is not known whether a similar score would be useful in hepatic cirrhosis.     

Retroperitoneoscopic nephrectomy for non-functioning kidneys related to renal stone disease

Laparoscopic nephrectomy has become the gold standard procedure for nonfunctioning or symptomatic benign kidneys due to renal calculi, obstructive, refluxive, and inflammatory nephropathies or renovascular hypertension. We aimed to investigate the effect of renal calculi as a reason of non-functioning on the progress and complication rates of the retroperitoneoscopic nephrectomy (RPN).During a 2-year period, 108 patients with benign renal conditions underwent RPN by single surgeon. Among these patients, total of 27 (Group 1) with a non-functioning kidney due to renal calculi were retrospectively compared with 27 patients (Group 2) with other benign renal conditions. The two groups were matched for age, body mass index, and previous renal surgery. We analyzed operative and post-operative findings and complications. The mean age and the BMI of the groups were similar. The operation time was significantly longer in Group 1 than Group 2 (p?=?0.0001). There was no significant difference between the groups with respect to mean hemoglobin drop postoperatively (p?=?0.9) and hospitalization time (p?=?0.06). The perioperative and postoperative complication rates were higher in Group 1 but not statistically different from Group 2 (p?=?0.19, p?=?0.29, respectively). RPN for nonfunctioning calculous kidneys is more challenging procedure and is associated with prolonged operation time related to difficult dissection of dense adhesions. It can be safely performed by experienced hands with similar perioperative and postoperative complication rates as well as for other benign conditions of the kidney.     

Fatal motorcycle accidents in Fars Province, Iran: a community-based survey

Objective: To identify the main characteristics of victims of motorcycle accidents in Fars Province, Iran. Methods: This cross-sectional study was conducted in Fars Province which has the fourth largest population of all 31 provinces in Iran from March 2009 to June 2010. We included data from all 542 recorded cases of fatalities due to motor vehicle accidents. Data were recorded from the forensic medicine registry consisting of demographic and accident-related information. Demographic information consisted of name, age, sex, status of fatal victim (motorcycle driver vs passenger) and educational level. Results: Of the 2 345 autopsy records from the forensic medicine archives, 542 (23.1%) gave the cause of death as motor vehicle accidents. Mean age of these victims was (31.4+/-6.5) years, and the male to female ratio was 28. Head injury was the most common cause of death in these victims, and overall they tended to have a low level of education. Motorcycle accidents frequently involved younger age groups (15-35 years), and head trauma related with non-use of a helmet was the most common cause of death. Conclusions: Head injury is frequent among victims in the province we studied. This situation may be related to the victims' low socioeconomic status and little education regarding traffic laws leading to speeding and disregard of these laws along with their weak enforcement.     

Genetic Factors Affecting Late-Onset Alzheimer’s Disease Susceptibility

Alzheimer’s disease is considered a progressive brain disease in the older population. Late-onset Alzheimer’s disease (LOAD) as a multifactorial dementia has a polygenic inheritance. Age, environment, and lifestyle along with a growing number of genetic factors have been reported as risk factors for LOAD. Our aim was to present results of LOAD association studies that have been done in northwestern Iran, and we also explored possible interactions with apolipoprotein E (APOE) status. We re-evaluated the association of these markers in dominant, recessive, and additive models. In all, 160 LOAD and 163 healthy control subjects of Azeri Turkish ethnicity were studied. The Chi-square test with Yates’ correction and Fisher’s exact test were used for statistical analysis. A Bonferroni-corrected p value, based on the number of statistical tests, was considered significant. Our results confirmed that chemokine receptor type 2 (CCR2), estrogen receptor 1 (ESR1), toll-like receptor 2 (TLR2), tumor necrosis factor alpha (TNF α), APOE, bridging integrator 1 (BIN1), and phosphatidylinositol-binding clathrin assembly protein (PICALM) are LOAD susceptibility loci in Azeri Turk ancestry populations. Among them, variants of CCR2, ESR1, TNF α, and APOE revealed associations in three different genetic models. After adjusting for APOE, the association (both allelic and genotypic) with CCR2, BIN1, and ESRα (PvuII) was evident only among subjects without the APOE ε4, whereas the association with CCR5, without Bonferroni correction, was significant only among subjects carrying the APOE ε4 allele. This result is an evidence of a synergistic and antagonistic effect of APOE on variant associations with LOAD.     

Speech performance and oral impairments with lingual and labial orthodontic appliances in the first stage of fixed treatment: A randomized controlled trial

Objectives:To compare (1) speech performance based on an auditive analysis and sonagraphy and (2) levels of oral impairment between fixed lingual and labial orthodontic appliances.Materials and Methods:Thirty-four patients with Class I division 1 malocclusion and moderate crowding of upper teeth were distributed randomly into two groups. Seventeen patients in group A (mean age: 20.6 years; standard deviation [SD]: 2.9 years) were treated with fixed lingual appliances (Stealth®, AO, Sheboygan, Wisc), whereas 17 patients in group B (mean age: 21.8 years; SD: 3.3 years) were treated with conventional fixed labial appliances. Speech performance was tested using spectrographic analysis of fricative /s/ sound before, immediately after (T1), 1 month after, and 3 months after bracket placement. The levels of oral impairment were assessed using standardized questionnaires.Results:A significant deterioration in articulation was recorded at all assessment times in group A but only at T1 in group B. Significant intergroup differences were recorded at all assessment times (P < .001). Speech difficulties were significantly higher in the lingual brackets group after 1 month of bracket placement (P < .001). Soft tissue irritation and chewing difficulty were significantly higher in the lingual appliance group after 24 hours of bracket placement (P < .001).Conclusions:The lingual appliance is more problematic than the labial one in terms of speech articulation. Although patients with both appliances suffered from different degrees of oral impairment, patients with lingual appliances had more untoward effects, particularly during the first month of treatment.     

Detection of Infection with Larval Stages of Ornithobilharzia turkestanicum using PCR in Field-Collected Snails of Lymnaea gedrosiana from Northwestern Iran

Background

Infection with Ornithobilharzia turkestanicum has been reported in a wide range of animals worldwide. This study was undertaken to assess the utility of polymerase chain reaction (PCR), for detecting the infection with O. turkestanicum larvae stages in Lymnaea gedrosiana.

Methods

A total of 6,759 Lymnaeidae snails were collected from six aquatic habitats in West Azarbaijan, northwest Iran. Of these, the snails of L. gedrosiana were identified. To detect infected L. gedrosiana with the larval stages of O. turkestanicum, they were subjected for cercarial shedding and molecular examinations. The genomic DNA was extracted and PCR was performed to specifically amplify a fragment of the nuclear 28SrRNA gene of O. turkestanicum.

Results

Of all collected snails, 5.4% (365/6,759) were the snails of L. gedrosiana. The cercarial shedding method revealed that 23.56% (86/365) of the snails were infected. The PCR patterns confirmed that 28.77% (105/365) snails of L. gedrosiana were infected with larval stages of O. turkestanicum. The infected snails were observed in five studied sites. The highest infection rate (66.66%, 20/30) was recorded in the snails of Ghargologh in the northern part. Only 35.24% (37/105) of the infected snails were from the plain areas, whereas the remaining existed in high altitudes.

Conclusion

It was concluded PCR method could be an efficient and fast method for uncovering the actual rate of infection with larval stages of O. turkestanicum in the snails of L. gedrosiana. This method can be also useful for the domestic animals and public health management programs in the country.