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

In the present study, 25% EDTA, in gel form, was used to analyse its micromorphological effects on tooth surfaces with the objective to see the effectiveness of EDTA in etching so as to replace phosphoric acid as an etchant. EDTA has neutral pH (6.4 - 7.4) and is known to open & widen the dentinal tubules as well as remove the smear layer. An in vitro study was conducted on orthodontically extracted premolars with 25% EDTA as an etchant which was applied on prepared tooth surfaces for 15 seconds, 1 minute and 3 minutes. The effects of EDTA gel was observed under SEM and results tabulated and evaluated. There was statistically significant differences between the 3 etching time groups and the results indicate that etching with 25% EDTA for 15 seconds is inadequate. The best results were obtained in the 3 minute time etch group. The results so obtained can be attributed to the fact that EDTA acts selectively and/or requires more time for action.
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PMID:Etching with EDTA--an in vitro study. 1470 Mar 40

Questions over the usefulness of a self-etching primer with resin adhesive in the bonding of orthodontic brackets remain unsolved. The purpose of this study was to determine the effects of using Multibond, a new methyl methacrylate (MMA)-based resin cement with self-etching primer, on the shear bond strength of orthodontic brackets compared with Superbond C&B, which is a well-known MMA-based resin cement containing phosphoric acid etching. Metal or plastic brackets were bonded to etched or self-etching primed bovine teeth using Superbond C&B or Multibond. The shear bond strengths were measured after immersion in water at 37 degrees C for 24 hours. Data were analyzed by two-way analysis of variance and Scheffe's test. The surface appearances of the teeth after phosphoric acid etching or self-etching priming were observed by field-emission scanning electron microscopy (FE-SEM). Metal brackets bonded with Multibond had a significantly lower shear bond strength than metal brackets bonded with Superbond C&B. No significant differences in shear bond strength were observed between Multibond and Superbond C&B when plastic brackets were bonded to the enamel. The shear bond strength of metal brackets bonded with Multibond was comparable with that of plastic brackets bonded with Superbond C&B. Adhesive remnant index score showed a tendency of more residual resin cement remaining on the teeth when metal brackets were bonded with Multibond. FE-SEM observation revealed less dissolution of the enamel surface resulting from treatment with Multibond self-etching primer as compared with phosphoric acid. Thus, the Multibond system may be a candidate for bonding orthodontic brackets with the advantage of minimizing enamel loss.
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PMID:Assessing the performance of a methyl methacrylate-based resin cement with self-etching primer for bonding orthodontic brackets. 1471 36

It has been claimed that resin monomers may incompletely penetrate into demineralized collagen network, which could form a weak hybrid layer. In consequence, it has been proposed that removal of the exposed collagen network could improve adhesion to dentine. The interface between a water/ethanol-based one-bottle adhesive (Single Bond, 3M) which is devoid of acid monomers, and deproteinated surface of primary dentine was evaluated by SEM. Dentine disks were obtained from 20 primary teeth. Two disks were used to standardize the application time of sodium hypochlorite (NaOCl) for getting an effective deproteination. The remaining 18 disks were equally divided into two groups and treated as follows: control group (CG) 35% phosphoric acid (PA) for 15s; treated group/deproteination (TG) 35% PA for 15s+10% NaOCl for 3 min. Single Bond and Z250 (3M) were placed on all disks according to the manufacturer's instructions. The 18 resin-dentine disks were fractured to obtain hemi-disks and processed for SEM. The examination of the CG specimens showed a typical hybrid layer and the presence of numerous tags with few and short microtags. The TG specimens, which did not present hybrid layer, also exhibited numerous tags, with few and short microtags. Some areas between the tags showed fibrillar-like projections, which appeared to be mineralized collagen fibrils, which were incorporated into the adhesive. Thus, our results suggest that some chemical interaction may occur between mineralized dentinal collagen and the adhesive used.
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PMID:Micromorphological analysis of the interaction between a one-bottle adhesive and mineralized primary dentine after superficial deproteination. 1512 Apr 96

Calcium phosphate growth on chitin phosphorylated fibres was studied using scanning electron microscopy and energy dispersive X-ray analysis (SEM, EDX), micro-Fourier transform infrared spectroscopy (FTIR), and solid state magic angle spinning nuclear magnetic resonance (MAS NMR) techniques. The C6 chemical shift positions of 13C MAS NMR in the chitin fibres phosphorylated using urea and H3PO4 are obvious indicating that phosphorylation takes place not in the C1 but in the C6 region. Micro-FTIR and 31P MAS NMR suggested that ammonium hydrogen phosphate formed during the phosphorylation procedure. Chitin fibres phosphorylated using urea and H3PO4 and then soaked in saturated Ca(OH)2 solution at ambient temperature, which lead to the formation of thin coatings formed by partial hydrolysis of the PO4 functionalities, were found to stimulate the growth of a calcium phosphate coating on their surfaces after soaking in 1.5xSBF solution for as little as one day. The thin layer after Ca(OH)2 treatment functioned as a nucleation layer for further calcium phosphate deposition after soaking in 1.5xSBF solution. EDX-measured Ca : P ratios of the coatings of Ca(OH)2-treated phosphorylated chitin in 1.5xSBF solution suggested that calcium-deficient apatite was formed.
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PMID:Growth of calcium phosphate on phosphorylated chitin fibres. 1534 22

The purpose of this study was to examine the effectiveness of self-etching primer in adhering 4-META/MMA-TBB resin to bovine enamel. In this study, we designed an original self-etching primer which contained an aqueous mixture of 4-MET, 35 wt% HEMA, and ferric chloride. The polished bovine enamel surface was treated with self-etching primer for 30 seconds. Tensile bond strength of 4-META/MMA-TBB resin to enamel was measured after 1-day immersion in water at 37 degrees C. The self-etching primer containing 30 wt% 4-MET and 35 wt% HEMA (4MET30) gave a significantly higher bond strength of 11.2+/-2.8 MPa than other self-etching primers. The addition of ferric chloride into 4MET30 primer significantly decreased tensile bond strength. SEM observation revealed that 4MET30 treatment produced no distinct dissolution on enamel. When compared with phosphoric acid etching, the self-etching primer containing 30 wt% 4-MET and 35 wt% HEMA was more superior in adhering 4-META/MMA-TBB resin to enamel.
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PMID:Tensile bond strength of 4-META/MMA-TBB resin to ground bovine enamel using a self-etching primer. 1551 Aug 53

The formation of a hybrid layer is essential for bonding of dental composites to dentine. The objective of this study was to examine the effects of various etchants/conditioners and dentine bonding systems on dentine surfaces utilising a Field Emission Environmental SEM (FE-ESEM). Twenty one, freshly extracted human molar teeth were utilised. Dentine without resin application was initially observed both wet and dried in the following conditions: (1) fractured surface, (2) smear layer, and (3) smear layer removed with 37% phosphoric acid. Resin infiltration into dentine was then studied after applying Scotchbond 1, Optibond Solo, Prime & Bond NT, or Prompt L-Pop systems. Scotchbond 1, Optibond Solo, and Prime & Bond NT resins penetrated the dentine tubules and created hybrid layers; although, in some cases Prime & Bond NT only created a partially filled hybrid layer. No polymerised resin or hybrid layer was observed for Prompt L-Pop. The FE-ESEM permitted observation of specimens at near in-vivo wet conditions.
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PMID:Resin-infiltrated-dentine--a FE-ESEM microscopy investigation. 1555 13

It has been reported that the tensile bond strength between the 4-META/MMA-TBB resin and dentin pretreated with 10% citric/3% ferric chloride solution decreased after immersion in water for 2 years. The current study investigated the effect of an experimental dentin conditioner on the bonding of 4-META/MMA-TBB resin to dentin after thermocycling. The experimental conditioner was an aqueous solution of 10% ascorbic acid and 5% ferric chloride (Exp). Human teeth were prepared to expose flat dentin surfaces. These were treated sequentially with 40% phosphoric acid, 10% sodium hypochlorite, and the experimental conditioner. A commercially available dentin conditioner, an aqueous solution of 10% citric/3% ferric chloride (10-3) was used for a control group. Stainless steel rods were bonded to the pretreated dentin surfaces with the use of the 4-META/MMA-TBB resin. Tensile bond strengths were determined after 0, 5,000, 10,000, 20,000 themocycles. All data were analyzed by ANOVA, and differences among groups were analyzed by Duncan's new multiple range test (n = 10, p < 0.05). The experimental group showed no significant decrease in bond strength through 20,000 thermocycles, while the control group exhibited significant decrease after 10,000 thermocycles. Mean bond strength of the experimental groups were significantly higher than those of the control group at both 10,000 and 20,000 thermocycles. A hybrid layer could not be identified in SEM micrographs of the experimental groups. 10-3-conditioned specimen SEMs displayed crack formation between the adhesive resin and a hybrid layer. The experimental dentin pretreatment improved the bond strength of a 4-META/MMA-TBB resin to human dentin compared to 10-3 treatment after thermocycling.
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PMID:Improvement of the bond strength of 4-META/MMA-TBB resin to collagen-depleted dentin. 1562 72

This study examined the effect of different acidic treatments and the role of a phosphate monomer in a silane coupling agent on the durability of the dual-cure resin cement/silicon oxide bond. Ceramic blocks (Vita Celay Blanks) were cut into multiple 3 mm-thick slices and polished using 600 grit SiC paper. Two pairs were left untreated [controls (CTRL)], two pairs were treated with 40% phosphoric acid and rinsed with water for 30 s (PA), and another two pairs treated with 20% hydrofluoric acid followed by 30 s water rinsing (HF). Half the specimens were silanated with Tokuso Ceramics Primer (TCP) (Tokuyama) and the other half with TCP formulated without phosphate monomer (TCP-NoPM). All the pairs were bonded with Bistite II dual-cure resin cement (Tokuyama) and light cured. After 24 h water storage at 37 degrees C, 0.7 mm-thick slabs were serially sectioned. Immediately, after 6 months and after 1 year of water storage, two slabs were randomly selected from each subgroup, and sliced into beams (6 x 0.7 x 0.7 mm) for the microtensile bond strength (muTBS) test. The muTBS data were statistically analyzed using multiple Wilcoxon Signed Rank tests (p < 0.05). Failure modes were determined using a confocal laser-scanning microscope. Ceramic surface morphology after the different acidic treatments was examined using an SEM. After 1 day, in the case of silane treatment with TCP, there were no significant differences in muTBS between the control and acid-treated groups (p > 0.05), whereas with TCP-NoPM, the muTBS of the control was significantly lower than the acid-treated groups (p < 0.05). All the TCP and acid-treated TCP-NoPM groups exhibited significant reductions in muTBS after 6 months (p < 0.05). After 1 year, the muTBS of the acid-treated TCP groups were not significantly different from the control TCP group (p > 0.05). There was also no significant difference between the HF-treated TCP and TCP-NoPM groups (p > 0.05) after 1 year, all exhibiting greater than 10 MPa tensile bond strength. It is suggested that acidic pretreatment of the ceramic surface does not improve the durability of the dual-cure resin cement/silicon oxide ceramic bond when an acidic phosphate monomer is present as an activator in a ceramic primer.
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PMID:Effect of acidic pretreatment combined with a silane coupling agent on bonding durability to silicon oxide ceramic. 1562 74

Examination of the auto-cure glass-ionomer cement (GIC)-tooth interface using conventional SEM techniques causes severe dehydration and subsequent fracturing of the GIC, hampering accurate assessment of the GIC-tooth interface. A simple, accurate impression technique was developed to examine the GIC chemical fusion zone. Samples of GIC were bonded to prepared cavities and tooth surfaces that had been conditioned with 10% polyacrylic acid for 10 s and allowed to mature for 24 h in neutral buffered saline, sectioned under water and then acid etched with 37% phosphoric acid for 30 s to remove sectioning smear layer and to highlight surface morphology, rinsed and gently dried. Optibond Solo Plus was then applied and photo-polymerized. Increments of posterior hybrid composite were then bonded onto the Optibond and photo-polymerized. The tooth sections with attached GIC were then dissolved off the bonded composite with 18% HCl for 4 days. Subsequent SEM examination of the resin impressions created with this technique provided high-quality, detailed images of the GIC chemical fusion zone, without the development of the fracture artefacts associated with the desiccation of GIC. The resin impression technique described proved to be a simple and successful method for providing accurate SEM images of the GIC-tooth chemical fusion.
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PMID:A resin impression SEM technique for examining the glass-ionomer cement chemical fusion zone. 1565 61

This in vitro study morphologically evaluated the effect of some current surface pre-treatments on dentin, using scanning electron microscopy, and related these morphological alterations to clinical implications. The labial surfaces of 30 bovine lower incisors were ground to obtain a flat dentin surface and were finished with 600-grit SiC paper to produce standardized smear layers. The teeth were randomly divided into six groups of five each. Group 1 was the control group, smear layer covered dentin; Group 2 was etched with 37% phosphoric acid (PA) for 15 seconds; Group 3, 37% PA for 15 seconds, followed by 10% NaOCl for 60 seconds; Group 4, 10% NaOCl for 60 seconds; Group 5, a self-etching primer (Clearfil SE Bond, CSEB-primer) was applied for 20 seconds; Group 6, CSEB-primer for 20 seconds, followed by NaOCl for 60 seconds. The specimens were fixed, dehydrated, dried and analyzed by SEM. Treatment with 37% PA removed the smear layer, funneled the tubules and resulted in a collagen-rich surface which appeared to have collapsed in its outermost part, producing a dense surface layer covered with silica particles. When 37% PA treatment was followed by 10% NaOCl, the collagen network was removed to reveal an eroded, rough mineral surface with numerous lateral branches and larger than normal tubular orifices. The action of 10% NaOCl on the smear layer-covered dentin showed no significant alteration in surface morphology. The treatment with CSEB-primer dissolved the smear layer but only partially dissolved the smear plugs. The tubules did not present the typical funnel shape seen following PA treatment. These morphological aspects on dentin surface must influence bonding results. The dentin surface alterations produced by PA appeared to be a very severe demineralization pattern, quite irregular and less permeable to monomer infiltration, while the surface provided by the self-etching primer appeared to be a more uniform, less porous surface, and the association with simultaneous monomer infiltration may reduce the occurrence of mistakes in clinical bonding procedures.
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PMID:The in vitro morphological effects of some current pre-treatments on dentin surface: a SEM evaluation. 1585 6


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