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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In three groups (n = 12 each) of male controls (22--43 years), patients with recurring calcium urolithiasis (21--36 years) and hyperparathyroidism (HPT; 17--71 years) proven by surgery renal cyclic adenosine monophosphate (RcAMP), fractional tubular phosphate reabsorption and serum parathyroid hormone (PTH) were measured during endogenous creatinine clearance. RcAMP (muMol/g creatinine) was: controls 1.48 +/- SEM 0.27; stone formers 2.037 +/- 0.343 (not significantly different); HPT 6.234 +/- 0.454 (p less than 0.001). There is no overlap between HPT and controls. Phosphate reabsorption is least in HPT (0.84 +/- 0.015), higher in controls (0.924 +/- 0.004) and stone formers (0.941 +/- 0.007). All differences are statistically significant. Under the conditions selected (moderate hydration of individuals) Serum PHT (pg-equiv/ml) is lowest in stome formers (less than 100--339), higher in controls (less than 100--933) and HPT (400--1150). there is no overlap in PHT between the former and the latter group but a marked one between controls and HPT. For clinical purposes the resulting diagnostic uncertainty in a given patient can be overcome by additional determinations of RcAMP and ionised serum calcium: when referring to serum PTH HPT patients fall outside, RCU patients within 2 standard deviations of either parameter in control subjects. This procedure presently appears superior to those proposed in the past (urinary cAMP etc.) but requires confirmation in larger patient populations. Moreover, since HPT prevails in middle and upper age decades, their RcAMP values and those of RCU patients should be related to a range seen in closely age- and sex-matched controls.
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PMID:[Evaluation of renal cyclic adenosine monophosphate, serum parathyroid hormone and phosphate reabsorption in recurrent calcium urolithiasis, healthy controls and hyperparathyroidism (author's transl)]. 21 Mar 11

Taglike projections of resin into the etched enamel surface and longitudinally cut enamel were studied under the SEM. Three methods of bonding, including the use of a bonding agent and a primer, were compared. Freshly extracted teeth were pumiced, rinsed, and dried. The enamel surface was etched for a minute with phosphoric acid. Adaptic with bonding agent, Simulate with primer, and Simulate without primer were then applied to the etched enamel. After the teeth were sectioned, the enamel was etched with phosphoric acid and viewed under the SEM. The resin projections into the etched rod ends at the enamel surface were 5 to 10 mu in length, with similar cuplike and coneline patterns of tags for the three methods of bonding. Troughlike and ridgelike projections into the longitudinally cut enamel were 3 to 5 mu in length; patterns of tags were similar for the three bonding methods. No observable differences in length and pattern of tags were noticed among the three bonding methods.
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PMID:A scanning electron microscope comparison of three methods of bonding resin to enamel rod ends and longitudinally cut enamel. 36 1

Micropuncture studies demonstrate phosphate reabsorption in proximal tubules and between the late proximal and early distal convoluted tubule accessible to micropuncture. To further define the sites of phosphate reabsorption, the stationary microperfusion technique was applied to proximal and distal nephron segments. Phosphate reabsorption was evaluated in superficial loops of proximal tubules, descending segments beyound late proximal tubules accessible to micropuncture, ascending segments up to the point of micropuncture in the distal tubule, and superficial loops of distal tubules of thyroparathyroidectomized rats. Microperfusates of 1.3 or 2.6 nl (100 mmol/1 mannitol, 100 mmol/l NaCL, 32P-phosphate and 3H-inulin) were injected and then withdrawn after contact times of 2--108 s. Phosphate recovery relative to that of inulin was determined. A steep exponential decline of phosphate recovery (R) iwth increasing contact time (t) was observed in the superficial proximal tubule and descending segments. The slopes of the logarithmic regressions (10log R)/t, +/- SEM) were: -1.68 +/- 0.33 and -1.21 +/- 0.24min-1 in superficial proximal tubules and descending segments respectively. In contrast, no significant decline in phosphate recoveries (-0.02 +/- 0.04 and + 0.11 +/- 0.10 min-1) was apparent in the ascending segments and distal tubule. It is concluded that phosphate is reabsorbed in the proximal convoluted tubule and adjacent descending segments of the superficial nephron and that there is no significant phosphate reabsorption in distal convoluted tubules and adjacent ascending segments.
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PMID:Stationary microperfusion study of phosphate reabsorption in proximal and distal nephron segments. 55 98

In this investigation, the penetration of different resins into the etched enamel surface and the effect of their viscosity on the penetration of these materials were studied. Freshly extracted teeth were pumiced, rinsed, and dried. The enamel surface was etched by using a solution containing 50% phosphoric acid for one minute; in one group the teeth were etched for two minutes. A layer of enamel surface of another group of teeth was removed before etching; these teeth were etched for one minute. Three different resins--Nuva-Seal, Concise Enamel Bind, and Restodent--were applied to the acid-etched enamel surface for one minute. The Concise composite resin also was applied to the enamel surface of a group of teeth etched for the same period of time. Observations with SEM and polarized light microscopy showed penetration of all the materials into the etched enamel surface to be 5 mum to 10 mum, with a mean of 7 mum. There was no difference in the penetration of these materials despite their different viscosities. The removal of a layer from the enamel surface was not effective in the penetration of the materials.
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PMID:Penetration of restorative resins into acid-etched human enamel. 79 92

The purpose of this paper was to study by means of scanning electron (SEM) and optical microscopy the adaptation of the low-viscous non-composite. Nuva-Seal and of the three high-viscous composite restorative materials Adaptic, Compocap and Concise to phosphoric acid etched enamel surfaces from symmetric areas of pairs of contralateral human permanent anterior teeth. The SEM study demonstrated that the two types of material equally well reproduce the details of the enamel surface; the light microscopic observations showed that the length and shape of resin tags in the enamel surface are independent of the materials examined. The observations seem to allow the conclusion that bonding of composite restorative resins to phosphoric acid etched enamel surfaces is not conditioned by the employment of an intermediate film of a low-viscous non-composite resin.
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PMID:Adaptation of resinous restorative materials to acid etched enamel surfaces. 105 79

Ten shiny erosion lesions were divided horizontally, in vivo such that the gingival half was prepared and the incisal half remained unprepared. Both were etched simultaneously with 32% H3PO4 for 20 seconds, rinsed and restored using the All Bond wet technique and P50 composite. The teeth, which were extracted as part of a treatment plan, were sectioned vertically midway through the restorations. Polyvinyl siloxane impressions of the tooth/resin interface were taken and examined by SEM for the presence of gaps. The teeth were then demineralized and the fitting surfaces of the restorations were examined for resin penetration into the dentin. Results showed that there were no gaps present in any of the interfaces. The most proliferative and deep resin penetration occurred in the prepared/etched halves.
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PMID:Interfacial morphology of resin composite and shiny erosion lesions. 130 79

Information related to bonding of orthodontic brackets to fluorotic teeth is scanty. The purpose of this study was to compare, in vitro, the tensile bond strength and the bond failure site of brackets bonded directly to fluorotic and nonfluorotic teeth. The etching patterns were also evaluated. The study involved 26 teeth classified as score 3 and 4, and 26 as score 0 with the Thylstrup and Fejerskov's (TF) fluorosis index. In addition to the clinical classification, difference in the concentration of fluoride in the teeth was verified by acid etching. Brackets were bonded with a composite resin after etching the enamel surface with 40% phosphoric acid for 60 seconds. Tensile bond strength was determined with an Instron testing machine. The bond failure site was assessed by the percentage of residue cement on the tooth surface after debonding and the etching pattern by SEM. The mean concentration of fluoride was 2888.5 ppm (SD 1081.7) in the fluorotic teeth and 1227.1 ppm (SD 526.3) in the nonfluorotic teeth. The mean bond strength was 7.8 N/mm2 (SD 1.47) for the fluorotic teeth and 8.6 N/mm2 (SD 2.19) for the nonfluorotic teeth. The difference between the means for bond strength was not statistically significant (p greater than 0.05). Bond failure site was primarily at the bracket-adhesive interface. The mean percentage of adhesive on the enamel surface after debonding was 70% (SD 25.90) for the fluorotic teeth and 75% (SD 24.66) for nonfluorotic teeth. The difference in the means was not statistically significant (p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Tensile strength of orthodontic brackets bonded directly to fluorotic and nonfluorotic teeth: an in vitro comparative study. 138 89

This study examined the relationship between resin and dentin both in vitro and in vivo using phosphoric acid conditioning. Four groups of 10 teeth each had standardized Class V preparations made with the gingival cavosurface margin in the root. In Group 1, involving freshly extracted teeth, the enamel and dentin was conditioned with 37% phosphoric acid gel for 15 seconds. NTG-GMA/PMDM was applied to the enamel and dentin followed by an application of BIS-GMA/HEMA and restoration with P50. Group 2 served as a control omitting the conditioning step. Groups 3 and 4 were treated similarly to Groups 1 and 2 except in vivo and extracted 2 weeks after restoration placement. All teeth were sectioned longitudinally through the restoration. Impressions were taken of the tissue/restoration interface and examined by SEM for disclosure of gaps. The teeth were then demineralized and the fitting surface of the restoration was examined by SEM for evidence of resin penetration into the tissue. The results showed a total absence of gaps both in vitro and in vivo after acid conditioning compared to the controls commonly showing gaps. Penetration of resin into the dentin to form a zone of diffusion or hybrid layer was observed only in the conditioned specimens. The phenomenon was observed both in vivo and in vitro. It was concluded that a significant potential exists for phosphoric acid conditioning of dentin to promote bonding.
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PMID:Micromorphological relationship between resin and dentin in vivo and in vitro. 138 27

The purpose of this study was to determine whether amalgam bonded to tooth structure with an adhesive resin cement can increase the fracture resistance of restored teeth. Extracted paired upper premolars were prepared for G.V. Black type mesioocclusodistal amalgam restorations. In one tooth of each pair (the experimental group), the enamel walls were etched with phosphoric acid and were painted with an adhesive resin (Panavia), and amalgam was condensed and carved. For the other tooth in each pair (the control group), amalgam was placed in the same manner but was not etched and lined with resin. The teeth were thermocycled and mounted for testing and then were loaded until fracture. A significant difference (p less than 0.05, the paired Student's t-test) was found in the force needed to fracture the bonded amalgam group (70.5 +/- 21.6 kg) compared with that needed to fracture the conventional amalgam group (60.3 +/- 16.8 kg). SEM examination of fractures at the interface occurred predominantly within the resin.
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PMID:Effect of bonded amalgam on the fracture resistance of teeth. 150 Nov 70

In this in vitro study, the effect of application techniques on marginal adaptation of thermal cycled class V restorations restored with an actual dentinal adhesive were quantitated using SEM and dye penetration. Under optimal application conditions, excellent results were generated: though a simple bulk insertion technique was used, no difference was found between enamel and dentin margins before and after thermal loading. On the other hand, contamination of the bonding agent with saliva before composite resin insertion dramatically decreased the percentage of "excellent margin" in dentin and in enamel. Similar effects were found after protecting the bonding agent with an insulating gel. No improvement in marginal adaptation was found after reapplication of the bonding agent. The class V inlay did not show better results than the direct filling technique. However, postcured inlays performed better than their non-postcured counterparts. Without etching enamel with a phosphoric acid gel, but by priming its surface, approximately 80% of "excellent margin" were found in enamel before thermal cycling. This percentage decreased significantly after thermal loading. Restorations totally confined to dentin had slightly lower percentages of "excellent margin" than the mixed class V fillings. The results of this study indicated, that by using dentinal adhesives, little changes and deviations from the correct procedure result in significant alterations in marginal adaptation.
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PMID:[The effects of the processing technic on dentinal adhesion]. 152 19


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