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PubMed1989

Three-year study of cervical erosions restored with resin and dentin-bonding agent.

Cervical erosions without undercuts and traditional cavity preparation were restored with a light-activated microfilled resin in combination with two different dentin-bonding agents, Gluma and the chemically activated version of Scotchbond. In the Gluma group the final polishing was postponed for at least 1 day; in the Scotchbond group polishing was performed 5 to 15 min after polymerization. The results of the two clinical tests are therefore not comparable. Under these experimental conditions the cumulative 3-year survival rate for the fillings in the two groups were 96% (Gluma) and 66% (Scotchbond). It is concluded that cervical erosions should be restored without undercuts or traditional cavity preparation on the condition that the enamel is acid-etched, polishing of the gingival area is postponed, and an effective dentin-bonding agent is used.

Acid Etching, Dental↗
PubMedDate not supplied

Effect of collagen removal on shear bond strength of two single-bottle adhesive systems.

This study evaluated the effect of collagen removal on the shear bond strength for two single-bottle adhesive systems. The ultrastructure of the dentin after treatments and the dentin-resin interface were examined under SEM. The buccal and lingual surfaces of 80 extracted human third molars were ground to expose dentin. Teeth were randomly assigned to four groups and received the following treatments: Group 1(P&B 2.1), Prime & Bond 2.1 adhesive was applied according to the manufacturer's directions and Restorative Z100 composite resin was bonded to the dentin surface; Group 2 (P&B 2.1/NaOCl), the same procedures were followed as for Group 1 except that the surfaces were treated with 10% sodium hypochlorite (NaOCl) for one minute after acid conditioning; Group 3 (SB), Single Bond (3M) was applied according to the manufacturer's recommendations; Group 4 (SB/NaOCl), the same procedure was followed for Group 2, using Single Bond. The specimens were stored in humidity at 37 degrees C for 24 hours and tested in a shear mode at a crosshead speed of 0.5 mm/minute. The Kruskal-Wallis test and Multiple Comparisons were used for statistical analysis of the data. A one-minute exposure of dentin to 10% NaOCl following acid conditioning resulted in a significant increase of the dentin shear bond strength for Prime & Bond 2.1. The same treatment for Single Bond resulted in a significant reduction in bond strength. Groups 1 and 3 were not statistically different from each other. The presence of a collagen layer resulted in the formation of a hybrid layer and similar values of adhesion for both adhesive systems. The results may suggest that collagen removal improves the bond strength for this acetone-based adhesive system but several such systems would need to be investigated.

Acetone↗
PubMedDate not supplied

Cytotoxicity evaluation of single component dentin bonding agents.

This study evaluated the cytotoxicity of four single component dentin bonding agents: Syntac Single Component, Prime & Bond 2.1, Single Bond and One Up Bond F. The test materials were applied on dentin discs of dentin barrier models in the same way as in the clinical procedures recommended by each manufacturer. Cell viability of L 929 after exposure with the bonding agents was determined by MTT assay. The results revealed that cell survival of the first three bonding agents was 60%, while the fourth was an impressive 93%. This study showed that a total-etching bonding system is more cytotoxic than a self-etching bonding system.

Acetone↗
PubMedDate not supplied

The clinical evaluation of a single-bottle adhesive system with three restorative materials in children: six-month results.

This study was designed to evaluate the clinical performance of a single-bottle adhesive system with three restorative materials placed in children using the total-etch technique. One hundred thirty restorations were placed on conservative preparations in 36 children using the incremental placement technique in a clinical environment. The restorations were evaluated within a week of placement (baseline) and again after six months. The criteria evaluated included retention, color match, marginal discoloration, marginal integrity, surface roughness, postoperative sensitivity, recurrent caries, and wear. Indirect evaluations of anatomical form, marginal adaptation, and wear also were conducted. Clinical evaluation demonstrated no significant differences between the three restorative materials. Five restorations had to be replaced: two compomer, two packable composite, and one amalgam. There was no clinically detectable wear in any of the restorations.

Acid Etching, Dental↗
PubMed1983

Selective isolation of endo-D-galacturonanase of Aspergillus niger based on interaction with tri(D-galactosiduronic acid) covalently bound to poly(hydroxyalkyl methacrylate).

A selective affinity-adsorbent for the extracellular endo-D-galacturonanase (E.C. 3.2.1.15) of Aspergillus niger was prepared by covalent coupling of tri(D-galactosiduronic acid) to Separon, a poly(hydroxyalkyl methacrylate) gel. Complexing of the enzyme with the adsorbent is pH dependent; maximal interaction occurs at the optimum pH for enzyme activity. The enzyme was quantitatively displaced from the adsorbent either by changing the pH or by bioelution with soluble tri(D-galactosiduronic acid) or other substrate. Within the range of substitution of Separon examined [content of tri(D-galactosiduronic acid) 1.7-6.7%] the amount of endo-D-galacturonanase retained was proportional to the content of affinity ligand. Under the same conditions, unsubstituted carrier did not complex with endo-D-galacturonanase. The dissociation constant of the affinity complex, as determined by zonal analysis, kinetic measurements, and by means of the adsorption isotherm KL (0.54 mmol.L-1), is close to the value (KI 0.44 mmol.L-1) obtained by the two first methods with soluble tri(D-galactosiduronic acid). The results show that adsorption of endo-D-galacturonanase on tri(D-galactosiduronic acid)-Separon is due exclusively to active-site-directed interaction with bound affinity-ligand.

Aspergillus niger↗
PubMed1980

Polymers containing enzymatically degradable bonds V. Hydrophilic polymers degradable by papain.

Copolymers of N-(2-hydroxypropyl)methacrylamide were prepared, in which synthetic polymer chains are joined by crosslinks containing oligopeptidic sequences degradable with papain, with the general structure P-(Gly)n-X-Y-NH-(CH2)6-NH-Y-X-(Gly)n-P (P is the polymer chain, n = 1,2; X...Phe, Val, Gly; Y...Lys, Gly, Tyr, Ala, Phe). The relationship between the structure of these polymeric substrates and their degradability with papain was investigated viscometrically. It was shown that -Phe-Lys- was the most suitable -X-Y- sequence. Extension of the oligopeptidic sequence by one amino acid residue causes a pronounced rise in the rate of cleavage of the polymeric substrates.

Acrylic Resins↗
PubMed1991

The effect of plasticizers on compatibility, mechanical properties, and adhesion strength of drug-free Eudragit E films.

The use of plasticizers to affect the properties of drug-free, self-adhesive Eudragit E-100 films with higher transparency was tested for possible transdermal drug delivery. Triacetin was found to be an effective first plasticizer for Eudragit E-100 polymer. In order to improve the flexibility and adhesiveness of Eudragit E-100 film plasticized with triacetin, a more flexible and adhesive, secondary plasticizer was added. Plasticizer-polymer compatibility was evaluated by measuring transparency, surface topography, and solubility. Secondary plasticizers with a low molecular weight and a solubility parameter similar to that of Eudragit E-100 polymer and triacetin were compatible. Further, a lower molecular weight or higher concentration of the secondary plasticizers might lead to greater plasticizing action, reduce tensile strength, and increase film elongation, independent of the hydrophilicity of the plasticizer. The adhesive strength of Eudragit E-100 film under a 180 degrees peel test was also affected by the molecular weight and solubility parameter of the secondary plasticizers used. The results indicate that PEG 200, propylene glycol, diethyl phthalate, and oleic acid can serve as a secondary plasticizer to improve the transparency, flexibility, and adhesion of Eudragit E-100 film.

Acrylic Resins↗
PubMed2005

Smart polymeric micelles as nanocarriers for oligonucleotides and siRNA delivery.

The development of in vivo delivery systems for oligonucleotides and siRNA is strongly desired to achieve their clinical applications. Recently, polyplex micelles, which are formed through an electrostatic interaction between nucleic acid compounds (DNA and RNA) and poly(ethylene glycol) (PEG)-polycation block copolymers, have received much attention due to their nanometric-scaled size and excellent biocompatibility. Here, three types of newly engineered block copolymers were developed to construct polyplex micelles useful for oligonucleotides and siRNA delivery: (1) PEG-polycation diblock copolymers possessing diamine side-chain with distinctive pKa for siRNA encapsulation into polyplex micelles with high endosomal escaping ability, (2) Lactosylated PEG-(oligonucleotide or siRNA) conjugate through acid-labile beta-thiopropionate linkage to construct pH-sensitive PIC micelles, and (3) PEG-poly(methacrylic acid) block copolymer for the construction of organic/inorganic hybrid nanoparticles encapsulating siRNA.

Hydrogen-Ion Concentration↗
PubMed1979

Methylmethacrylate metabolism in man. The hydrolysis of methylmethacrylate to methacrylic acid during total hip replacement.

Methylmethacrylate, the monomeric component of the polymethylmethacrylate cement used in orthopedic surgery, has been shown to undergo hydrolysis to methacrylic acid during hip replacement operations. Circulating levels of methacrylic acid were comparable with those of methylmethacrylate. Concentrations of both methylmethacrylate and methacrylic acid normally lay in the range 0--15 micrograms/cc. No correlation could be discerned between changes in the concentrations of methylmethacrylate and methacrylic acid, and changes in blood pressure.

Acetabulum↗
PubMed1993

SK&F 97426-A a more potent bile acid sequestrant and hypocholesterolaemic agent than cholestyramine in the hamster.

SK&F 97426-A is a novel bile acid sequestrant which was selected for comparison with cholestyramine in vivo because of its superior in vitro bile acid binding properties. The effects of the two sequestrants on faecal bile acid excretion, plasma total cholesterol, VLDL + LDL and HDL cholesterol and triglyceride concentrations and on liver enzymes involved in the synthesis and metabolism of cholesterol were investigated in normocholesterolaemic hamsters. Four studies were conducted to determine the relative potencies of the two resins using a range of doses of the sequestrants over treatment periods of up to 2 weeks. Curves fitted to the resulting data allowed common maximum responses and separate ED50s to be calculated for each sequestrant. The maximum response of both sequestrants was to increase bile acid excretion by 352% and lower plasma total cholesterol by 37-58%. LDL + VLDL and HDL cholesterol were reduced by 56-75% and 25-41%, respectively. SK&F 97426-A was 3 times more potent than cholestyramine at increasing the excretion of bile acids in the faeces and 2.1-3.4-fold and 2.3-3.2-fold more potent at lowering total plasma cholesterol and LDL plus VLDL cholesterol, respectively. In some of the experiments SK&F 97426-A was also more potent than cholestyramine at lowering HDL cholesterol. Plasma triglycerides were also lowered by both sequestrants by up to 31% after 1 week but the relative potency could not be determined. These HDL cholesterol and total triglyceride lowering effects of bile acid sequestrants in the hamster are known not to occur in people treated with cholestyramine. There were minimal differences between hamsters treated for 1 or 2 weeks in the relative potencies or ED50s calculated for the total plasma cholesterol, LDL + VLDL and HDL cholesterol. Both sequestrants may have been slightly more efficacious on these parameters after 2 weeks of treatment. Liver weights were reduced by about 15% by both sequestrants at 2% (w/w) in the diet for 1 week. The activities of the liver HMG-CoA reductase and cholesterol 7 alpha-hydroxylase were increased as expected, whilst the activity of the acyl-CoA:cholesterol acyltransferase was reduced by both sequestrants at this dose. SK&F 97426-A was, therefore, 2-3-fold more potent as a bile acid sequestrant and hypocholesterolaemic agent than cholestyramine when tested in the hamster.

Animals↗
PubMed1999

Organic leachables from polymer-based dental filling materials.

Results are reported from a study on the in vitro separation and identification of leachables from three different polymer-based dental filling materials by using a combined method of gas chromatography and mass spectrometry. The median number of separable organic leachables in these materials was between 14 and 22. Of these organic leachables the following were identified and quantified: DL-camphorquinone, 4-dimethylaminobenzoic acid ethyl ester (DMABEE), drometrizole, 1,7,7-trimethylbicyclo[2,2,1]heptane, 2,2-dimethoxy[1,2] diphenyletanone (DMBZ), ethyleneglycol dimethacrylate (EGDMA), and triethyleneglycol dimethacrylate (TEGDMA). Three of the leachables have previously been shown to provoke allergy. The range of log P(ow) values (representing the lipophilicity of these compounds) varied between 1.09 and 4.20. By multivariate data analysis, selected leachables from the tested materials were shown to separate into characteristic patterns. The results contribute to a characterization of potential hazardous compounds in polymer-based dental filling materials.

4-Aminobenzoic Acid↗
PubMed2002

Influence of composition on rate of polymerization contraction of light-curing resin composites.

A slow contraction may result in reduced gap formation when a restorative resin polymerizes in a dental cavity. It was the aim in the present work to investigate the rate of contraction in relation to composition of experimental light-curing resin composites. The monomer of the resin composites consisted of mixtures of BisGMA, TEGDMA, and in one series HEMA. The resins contained varying amounts of initiators, co-initiators, and inhibitor, and were made composite by adding a silanized glass filler to a content of 74% by weight of the composite paste. The polymerization contraction up to 120 sec was determined by means of the bonded-disk method. Within the ranges studied, the concentration of initiator and co-initiator in the monomer mixture had only an insignificant influence on rate of polymerization. In comparison to camphorquinone, the initiators 1-phenyl-1,2-propanedione and benzil reduced the rate of polymerization without affecting the final contraction. In comparison to N,N-dimethyl-p-aminobenzoic acid ethyl ester, N,N-cyanoethyl methylaniline was as effective, while N,N-diethanol-p-toluidine was less effective as co-initiator. A relatively high content of the inhibitor methoxyhydroquinone reduced the initial rate but not the final polymerization contraction. The rate of polymerization increased with the level of HEMA and TEGDMA in the monomer mixture. It was concluded that intrinsic slow cure may be obtained with certain compositions of resin composites without impairing the final extent of polymerization.

4-Aminobenzoic Acid↗
PubMed1989

Scanning electron microscope appearance of the enamel/composite/bracket areas using different methods of surface enamel treatment, composite mix and bracket loading.

Minimal plaque retention on and around orthodontic brackets is of paramount importance if iatrogenic tooth damage is to be avoided. This study made use of the scanning electron microscope to examine how variations in composite mix and finishing affected the smoothness and adaptation at the bracket, composite, and enamel interfaces. The study indicated that the optimum choice for good composite/enamel adaptation with a smooth composite surface and good composite/bracket adaptation involves the use of an intermediate unfilled resin layer, a paste/liquid mix of composite placed on a bracket which is optimally loaded, and no excess composite removed with an instrument.

Acid Etching, Dental↗
PubMed2006

In vitro microtensile bond strength of four adhesives tested at the gingival and pulpal walls of Class II restorations.

BACKGROUND: The authors compared the microtensile bond strength of teeth restored with four adhesives at the gingival and pulpal cavity walls of Class II resin-based composite restorations. METHODS: Five pairs of extracted third molars received two Class II preparations/restorations in each tooth. The authors randomly assigned each preparation to one of four adhesive groups: Adper Scotchbond Multipurpose Dental Adhesive (SBMP) (3M ESPE, St. Paul, Minn.), Clearfil SE Bond (CFSE) (Kuraray America, New York City), Prime & Bond NT (PBNT) (Dentsply Caulk, Milford, Del.) and PQ1 (Ultradent, South Jordan, Utah). They restored the teeth and obtained microtensile specimens from each cavity wall. Specimens were tested on a testing machine until they failed. RESULTS: The mean (+/- standard deviation) bond strengths (in megapascals) were as follows: SBMP (pulpal), 36.4 (17.2); SBMP (gingival), 29.7 (15.3); CFSE (pulpal), 50.8 (13.6); CFSE (gingival), 50.2 (14.0); PBNT (pulpal), 38.3 (19.2); PBNT (gingival), 38.9 (17.7); PQ1 (pulpal), 58.7 (8.7); and PQ1 (gingival), 54.5 (18.5). A two-way analysis of variance found an adhesive effect (P < .001) but no location effect (P >.05). CONCLUSIONS: PQ1 and CFSE performed the best. The results showed no significant difference in microtensile bond strength at the gingival wall versus the pulpal wall. CLINICAL IMPLICATIONS: Under in vitro conditions, a total-etch ethanol-based adhesive (PQ1) failed cohesively more often than did the other adhesives tested.

Acid Etching, Dental↗
PubMedDate not supplied

Shear bond strength between composite resin and denture teeth: effect of tooth type and surface treatments.

PURPOSE: The purpose of this study was to investigate the strength of the composite resin-denture tooth bond as affected by different tooth surface treatments. MATERIALS AND METHODS: Spectrum TPH was condensed on 112 mandibular first molar acrylic resin and composite resin denture teeth, which received seven different treatments: Four groups were treated with Prime & Bond NT adhesive, and three groups were treated with One Step adhesive. Four groups (two of each adhesive category) were treated with Composite Activator and air abrasion. In one group, AeliteFlo was used just before the condensation of Spectrum TPH. Bond strength was evaluated with a shear test device on a Monsanto testing machine. The results were evaluated statistically with two-way ANOVA and the Scheffé method. RESULTS: There was a significant interaction between denture tooth type and surface treatments. Bond strength of composite resin was greater to composite than to acrylic resin teeth when the bond was mediated only with adhesives. One Step adhesive and AeliteFlo resulted in a higher bond of composite resin to both types of teeth. Wetting tooth surfaces with Composite Activator did not increase the bond. CONCLUSION: When repairing denture teeth with composite resin and adhesives, the bond strength was higher with composite than with acrylic resin teeth, and there were differences between the adhesives used.

Acid Etching, Dental↗
PubMed2003

Fluoride uptake by enamel and dentin from bonding agents and composite resins: a comparative study.

The present study was performed to compare the amount of in vitro fluoride uptake by enamel and dentin from fluoridated bonding agent with non-fluoridated composite (Group I), non-fluoridated bonding agent with fluoridated composite (Group II) and fluoridated bonding agent with fluoridated composite resin (Group III). Sixty extracted premolars were selected and divided into three groups of 20 teeth each. Restorative materials were applied according to manufacturer's instructions into standard windows created in the teeth, cured and placed in de-ionised water for three months. The fluoride content of successive acid etch biopsy was determined by specific ion-electrode analysis. Although significant amount of fluoride uptake occurred in all the test groups, fluoride uptake was found to be highly significant in dentin when compared to enamel in Group, I, II and III (P<0.001). The fluoride uptake was greater by both enamel and dentin in Group III ie fluoridated bonding agent with fluoridated composite resin.

Acid Etching, Dental↗
PubMed2005

Longevity of bonds made by composite and polyacid-modified resins to dentin using a dual-cured adhesive system.

PURPOSE: To evaluate the microtensile bond strengths (MTBS) of a dual-cured dentin adhesive bonded to dentin using a light-cured resin-based composite (composite) or a polyacid-modified resin-based composite (compomer), and to investigate the effect of water aging on the bond strengths of these systems. METHODS: Flat dentin surfaces prepared from extracted human third molars were bonded with Prime&Bond NT Dual-Cured version (PBNT). Resin build-up crowns were constructed incrementally with two different materials: a composite (Z250) or a compomer (Dyract AP). When Dyract AP was used as the restorative material, half of the specimens were etched with 36% phosphoric acid, and the other half of the specimens were not etched. After storage in water for 24 hours or for 6 months, the teeth were sectioned to obtain bonded 1.3 mm2 beams containing the bonded interface. Each beam was tested in tension in an Instron machine at 0.5 mm/minute. Results were analyzed by multiple ANOVA and Student-Newman-Keuls multiple comparison tests. RESULTS: The group PBNT/Dyract AP bonded to acid-etched dentin showed the highest bond strength, in the 24-hour evaluation. Bond strength values decreased significantly after aging. The groups treated with PBNT in light-cured, dual-cured and self-cured modes performed equally well in the 24-hour evaluation. After 6 months of water aging, bond-strengths of the light-cured groups remained stable. By contrast, decreases in the bond strengths of the self-cured groups were observed.

Acid Etching, Dental↗
PubMedDate not supplied

Effects of an experimentally developed adhesive resin system and CO2 laser irradiation on direct pulp capping.

This study examined the wound healing process of rat pulp directly capped with various experimentally developed adhesive resin systems and treated with CO2 laser irradiation. The experimental adhesive resins used in this study were made from Clearfil Mega Bond (MB). The adhesive resin groups were capped with a combination of the following primers and bonding agents: commercially available MB primer (MBP), experimental MB primer containing 2wt% N-methacryloyl 5-aminosalicylic acid (5-NMSA: MP3) and 5wt% 12-methacryloyloxydodecylpyridinium bromide (MDPB: ABP); and commercially available MB bonding agent (MBB), experimental MB bonding agent containing 5wt% and 10wt% hydroxyl-calcium phosphate (hydroxyapatite: MB1, MB2) and 5wt% dicalcium phosphate dihydrate (brushite: MB3) as a reparative dentin-promoter. The combination of the three primers and four bonding agents yielded the 12 adhesive resin groups used in this study. The CO2 laser group was irradiated with a laser and directly capped with MB. The CO2 laser used was an Opelaser 03S II SP, and irradiation conditions were as follows: a power output of 0.5 W, superpulse mode 1, repeat pulse mode (a cycle of 10 msec irradiation and 10 msec interval), defocused beam (approximately distance 20 mm from pulp exposure surface) and an irradiation time of three seconds, with air cooling. The control group was capped with Dycal (DY) and MB. After the direct pulp capping procedures were undertaken, all cavities were restored with Clearfil AP-X resin composite. The rats were sacrificed on the 14th post-operative day. The specimens were alternately stained with Mayer's H & E, Hucker-Conn bacterial stain and the ABC method on TGF-beta1. These stained sections were observed using light microscopy and the following parameters were evaluated: pulp tissue disorganization, inflammatory cell infiltration, reparative dentin formation and bacterial penetration. The results of this study include the following: all experimentally developed bonding agent groups showed reparative dentin formation; whereas, the MBB-capped groups showed very little reparative dentin formation. The descending order regarding the amount of reparative dentin formation was MB2 > MB3 > MB1 >>> MBB, which tended to be dependent on the concentration of the blended reparative dentin-promoter. In terms of the quality of the formed dentin, it was observed that MB1-capped teeth tended to form tubular dentin; whereas, MB2- and MB3-capped teeth formed irregular and osteodentin types of dentin. Among the primers used, the descending order regarding the amount of reparative dentin and tubular type dentin formation was MP3 > MBP > ABP. The descending order of migration of macrophages and leukocytes was ABP > MBP > MP3. The CO2 laser group showed a very irregular fibrous dentin matrix in the vicinity of the denatured and carbonized tissue but definite reparative dentin formation was not observed. The control group showed reparative dentin, which was very thick, compared with the other groups. In all the groups, pulp tissue showed almost normal morphology. Positive staining of TGF-beta1 was only observed slightly in some specimens of all groups. There was no difference in the staining of each group. Based on the results of this study, it was concluded that the combination of MP3 (containing 2wt% 5-NMSA) and MB1 (containing 5wt% hydroxyapatite) was effective in initiating an early repair process after direct pulp capping. CO2 laser irradiation is effective for field control, but a longer observation time will be required to determine findings concerning dentin bridge formation.

Acid Etching, Dental↗