Correlation between fracture properties and clinical performance of composite resins in Class IV cavities

One hundred and two Class IV cavities were restored randomly with four composite resins. The restorations were assessed at six months, one year, two years and three years for surface chipping, bulk fracture and incisal wear. The data were correlated with various mechanical properties of the materials. A significant correlation was found between surface chipping/bulk fracture and fracture toughness (P = 0.002), elastic modulus (P = 0.006) and tensile strength (P = 0.045). There was a trend towards an association between incisal wear and both elastic modulus and inherent flaw size. Fracture toughness may be a useful indicator of the clinical performance of composites in Class IV cavities.     

Clinical and quantitative marginal analysis of feldspathic ceramic inlays at 4 years

The aim of this clinical study was to evaluate feldspathic ceramic inlays both by clinical criteria and quantitative margin analysis in continuation of an earlier, identically conducted 2-year study. Fifty feldspathic ceramic inlays were adhesively luted in Class II preparations with all margins located in enamel. The inlays were evaluated clinically according to modified USPHS criteria after 3 and 4 years. Quantitative margin analysis was performed with a scanning electron microscope (SEM). Clinically, the inlays showed no recurrent caries and no changes in colour, but superficial marginal discolouration (6%) was apparent after 4 years. Margins were perceptible clinically in 64% of the cases after 4 years. Quantitative margin analysis showed significantly more marginal gaps at the composite/ceramic interface than at the enamel/composite interface. There was neither a significant decrease in perfect margins nor a significant increase in marginal gaps and marginal imperfections at both interfaces between the third and fourth year. Clinically, the inlays performed very well up to 4 years. Clinical evaluation using an explorer only detected substance loss in the cementation gap. The SEM evaluation showed significantly higher changes in marginal qualities during the first 2-year interval of clinical service compared to the second 2-year interval following an exponential mathematical regularity. Quantitative margin analysis should be included in clinical long-term trials to detect early marginal deficiencies at the luting interfaces. Received: 1 September 1997 / Accepted: 31 October 1997     

Periodontal treatment during pregnancy decreases the rate of adverse pregnancy outcome: a controlled clinical trial

Objectives

The aim of this study was to evaluate the effects of non-surgical treatment of periodontal disease during the second trimester of gestation on adverse pregnancy outcomes.

Material and Methods

Pregnant patients during the 1^st and 2^nd trimesters at antenatal care in a Public Health Center were divided into 2 groups: NIG – "no intervention" (n=17) or IG- "intervention" (n=16). IG patients were submitted to a non-surgical periodontal treatment performed by a single periodontist consisting of scaling and root planning (SRP), professional prophylaxis (PROPH) and oral hygiene instruction (OHI). NIG received PROPH and OHI during pregnancy and were referred for treatment after delivery. Periodontal evaluation was performed by a single trained examiner, blinded to periodontal treatment, according to probing depth (PD), clinical attachment level (CAL), plaque index (PI) and sulcular bleeding index (SBI) at baseline and 35 gestational weeks-28 days post-partum. Primary adverse pregnancy outcomes were preterm birth (<37 weeks), low birth weight (<2.5 kg), late abortion (14-24 weeks) or abortion (<14 weeks). The results obtained were statistically evaluated according to OR, unpaired t test and paired t test at 5% significance level.

Results

No significant differences were observed between groups at baseline examination. Periodontal treatment resulted in stabilization of CAL and PI (p>0.05) at IG and worsening of all periodontal parameters at NIG (p<0.0001), except for PI. Significant differences in periodontal conditions of IG and NIG were observed at 2nd examination (p<0.001). The rate of adverse pregnancy outcomes was 47.05% in NIG and 6.25% in IG. Periodontal treatment during pregnancy was associated to a decreased risk of developing adverse pregnancy outcomes [OR=13.50; CI: 1.47-123.45; p=0.02].

Conclusions

Periodontal treatment during the second trimester of gestation contributes to decrease adverse pregnancy outcomes.     

Translational research on clinically failed zirconia implants

Objectives

To provide fractographic analysis of clinically fractured zirconia implants recovered with their cemented crown. To calculate bending moments, corresponding stress and crack onset location on the implant’s fracture surface using a mathematical model integrating spatial coordinates of the crown-implant part and occlusal loading obtained from 2D and 3D images.

郑健应用四物消风饮加减治疗小儿慢性荨麻疹临床经验

小儿慢性荨麻疹主要是以风团、瘙痒、痒无定处,易反复发作且病程较长为主要临床表现,目前,现代医学以抗组胺药物为主要治疗方法,中医主要以养血祛风为治则,辅以清热、利湿、散寒等治法,郑健教授在临床上擅长用四物消风饮加减治疗小儿慢性荨麻疹,颇有成效。     

Mash1 efficiently reprograms rat astrocytes into neurons简

To date, it remains poorly understood whether astrocytes can be easily reprogrammed into neurons. Mashl and Brn2 have been previously shown to cooperate to reprogram fibroblasts into neurons. In this study, we examined astrocytes from 2-month-old Sprague-Dawley rats, and found that Brn2 was expressed, but Mashl was not detectable. Thus, we hypothesized that Mashl alone could be used to reprogram astrocytes into neurons. We transfected a recombinant MSCV-MASH1 plasmid into astrocytes for 72 hours, and saw that all cells expressed Mashl. One week later, we observed the changes in morphology of astrocytes, which showed typical neuro- nal characteristics. Moreover, β-tubulin expression levels were significantly higher in astrocytes expressing Mashl than in control cells. These results indicate that Mashl alone can reprogram astrocytes into neurons.     

Circadian fluctuations in three types of sensory modules in healthy subjects

This study was designed to observe and compare the circadian fluctuations in tactile sense, joint reposition sense and two-point discrimination in healthy subjects. Twenty-one healthy adult subjects received perceptual ability tests through these three different sensory modules at approximately 9：00, 13：00 and 18：00 in a day. The distribution of ranking for perceptual ability was significantly different among the three different time points in each individual, with highest perceptual ability in the evening compared with noon and morning, in terms of tactile sense and two-point discrimination. These findings suggest that the perceptual ability of healthy subjects fluctuates according to the time points in a day.