Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RESINS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,153 records · Page 64Linked to original sources
PubMed2002

An investigation into the transverse and impact strength of "high strength" denture base acrylic resins.

A range of materials, often marketed as high strength resins is available. These materials are often expensive options to conventional heat-cured acrylic resin. The aim of this study was to investigate transverse and impact strength of five "high strength" acrylic resin denture base materials. A conventional heat-cured acrylic resin was used as a control. Specimens were prepared as specified in the International Standard Organization (ISO 1567: 1988) and British standards for the Testing of Denture Base Resins (BS 2487: 1989) and the British Standard Specification for Orthodontic resins (BS 6747: 1987) for transverse bend and impact testing. The impact strength was measured using a Zwick pendulum impact tester and the transverse bend strength measured using a Lloyds Instruments testing machine. The results showed that Metrocryl Hi, Luctitone 199 and N.D.S. Hi all had an impact strength which was significantly higher than the control. For the modulus of rupture, there was a significant difference between Sledgehammer and the other groups. There was no significant difference between the other groups and the control. For the modulus of elasticity, Sledgehammer produced the highest value followed by the control. The remaining four materials had a modulus of elasticity less than the control.

Acrylic Resins↗
PubMed2002

Antibacterial and physical properties of resin modified glass-ionomers combined with chlorhexidine.

The purpose of this study was to determine the effect on mechanical properties and antimicrobial activity of the addition of chlorhexidine (CHX) to a resin modified glass-ionomer (Photac-fil, ESPE, Norristown, PA, USA). Chlorhexidine diacetate was combined with a resin modified glass-ionomer material at a concentration of 5%. The samples were tested for hardness, tensile strength and erosion at 24 h and 6-week intervals and for elution of CHX and antimicrobial activity weekly for 6 weeks. At 24 h there was no significant difference in hardness between the two groups, but at 6 weeks the resin modified glass-ionomer group was significantly harder than the CHX groups (P < 0.05). The diametral tensile strength test indicated no difference between the control and CHX groups at 24 h or at 6 weeks. The jet erosion test demonstrated significantly less erosion with the CHX group at 24 h but at 6 weeks the CHX group showed significantly more erosion than the control group. The chemical assay data demonstrated a peak elution of CHX at week 1 with residual amounts at weeks 2 and 3. The microbial data demonstrated that the CHX group had a significant reduction in Streptococcus mutans numbers for weeks 1-3, but after week 4 there was no difference between the glass-ionomer with and without CHX. The addition of CHX to resin modified glass-ionomer altered hardness and erosion of the resin-modified glass-ionomer, but because there are no material specifications, it is difficult to determine clinical implications. Chlorhexidine did significantly improve the antimicrobial effect of the glass-ionomer which was consistent with the chemical assay data. The results indicated that the addition of CHX to resin modified glass-ionomer material (Photac-fil) did not seriously degrade the physical properties during the time period tested and that the addition of CHX resulted in a greater reduction in S. mutans when compared with glass-ionomer alone.

Analysis of Variance↗
PubMed2002

In situ microhardness evaluation of glass--ionomer/composite resin hybrid materials at different post-irradiation times.

The purpose of this paper was to evaluate in situ the microhardness of a composite resin, two resin-modified glass-ionomers and two polyacid-modified composite resins at different post-irradiation times. The materials analysed were: Z 100/3M (Z1); Fuji II LC/GC Corporation (Fu); Vitremer/3M (Vi); Freedom/SDI (Fr); and Dyract/Dentsply (Dy). Palatal intra-oral acrylic resin appliances were made for each of the 24 volunteers in the experiment. In each appliance, a specimen of each material was fixed. Microhardness tests were performed at 30 min, 1, 2, 4, 8, 24 and 48 h, 7, 10, 14, 17 and 21 days after initial light-curing. The analysis of variance followed by the Tukey test showed significant differences of microhardness among all materials (Fu < Vi < Fr < Dy < Z1) up to 48 h. From the seventh to the fourteenth day, statistical differences were not found between Freedom and Dyract (Fu < Vi < Fr=Dy < Z1). On the seventeenth and twenty-first days, Vitremer, Freedom and Dyract did not present statistical differences, but differed from Fuji II LC and Z 100 (Fu < Vi=Fr=Dy < Z1). The polynomial regression showed an increase of microhardness over time for the glass-ionomers/composite resin hybrid materials, although there were differences of microhardness among these materials. There was no significant changes in microhardness levels for the composite resin over time.

Adult↗
PubMed2003

Effects of chemical disinfectants on the transverse strength of denture base acrylic resins.

The disinfection of dental prostheses by immersion in a chemical solution should be capable of rapid inactivation of pathogenic microorganisms, without causing any adverse effect on the denture base resins. This study evaluated the effect of disinfection immersion on the transverse strength of two heat-cured resins. The denture base resins (Lucitone 550 and QC 20) were polymerized according to the manufacturers' instructions. After polymerization, the specimens were polished, and then stored in water at 37 degrees C for 50 +/- 2 h prior immersion in one of the following solutions for 10 min: 4% chlorhexidine, 1% sodium hypochlorite and 3.78% sodium perborate. The specimens were submitted to disinfection twice, simulating when dentures come from the patient and before being returned to the patient. Ten specimens were made for each group. The transverse strength was evaluated by a 3-point bend test. The flexural strength of the two denture base acrylic resins evaluated remained unaffected after immersion in the three solutions evaluated. In general, the QC 20 resin specimens exhibited lower transverse strength than the Lucitone 550 resin specimens, regardless of immersion solutions.

Acrylic Resins↗
PubMedDate not supplied

The use of ion-exchange resins as a blood preservation system.

A system using ion-exchange resins for the storage of whole blood was investigated. Blood was collected into CPD, thoroughly mixed and then divided into equal amounts. To one half of the split units, four grams of phosphate charged Amberlite IR-45 resin were added, while no additions were made to the other split units. Both aliquots were stored at 4 C, adhering to routine blood banking standards. The blood stored with the resin for up to 28 days maintained high levels of 2,3-DPG and adequate levels of ATP. This new resin system has several advantages over the present blood preservation technology. There is initial increase in pH that promotes greater glucose utilization. Inorganic phosphate is provided to maintain both ATP and 2,3-DPG levels. The resin buffers the blood and maintains a narrower pH range for red blood cell enzyme activity. The resin is totally inert, completely filterable and has the ability to adsorb bacteria from the suspending solution.

Adenosine Triphosphate↗
PubMed2000

Effectiveness of metal surface treatments in controlling microleakage of the acrylic resin-metal framework interface.

STATEMENT OF PROBLEM: Microleakage at the junction between the metal alloy and acrylic resin in a removable partial denture may result in discoloration, fluid percolation, and acrylic resin deterioration. The junction between a metal alloy and acrylic resin is an area of clinical concern. Failure of a removable partial denture may be linked to this interface. Enhancing resistance to microleakage at this interface may improve the long-term union between the 2 materials. PURPOSE: This investigation was designed to determine the effects of various metal surface treatment protocols on microleakage and bond strength between the metal alloy and acrylic resin used in the fabrication of a removable partial denture. MATERIAL AND METHODS: Ninety-six nickel-chromium-beryllium alloy specimens were randomly divided into 8 groups. After adaptation of baseplate wax, each specimen was invested. Subsequent to wax removal, each specimen was divided into a control half and an experimental half. Air abrasion, tinplating/oxidation, and silanation were evaluated individually and in all combinations. Heat-polymerized acrylic resin was processed against all specimens before storage in distilled water at 37 degrees C for 72 hours. Each specimen then was thermocycled in distilled water (3000 cycles) before immersion in sodium fluorescein dye for 24 hours. Counting grids that exhibited dye penetration under ultraviolet light exposure allowed assessment of microleakage. RESULTS: Air abrasion resulted in a significant decrease in microleakage when used individually and in all combinations (P<0.05). All experimental combinations that did not involve air abrasion demonstrated no significant reduction in measured microleakage between the experimental and control sides. Tukey's pair-wise comparison of the difference in the mean number of squares exhibiting microleakage between the control and treated sites for each experimental group revealed a significant difference, based on the involvement of air abrasion. Groups involving air abrasion did not differ significantly from each other (P<0.05). In addition, no significant difference was detected between groups not involving air abrasion (P<0.05). CONCLUSION: Air abrasion, alone and in combination with tinplating/oxidation and with silanation, resulted in a significant reduction in microleakage between the metal alloy and acrylic resin.

Acrylic Resins↗
PubMed2002

Shear bond strength of resin cements to both ceramic and dentin.

STATEMENT OF PROBLEM: All ceramic restorations benefit from resin cement bonding to the tooth. However, the literature is unclear on which cement, ceramic conditioning treatment, and dentin bonding agent produce the highest and longest-lasting bond strength. PURPOSE: This in vitro study evaluated immediate and 6-month shear bond strengths between a feldspathic ceramic and 4 different resin cements with the use of 6 different surface-conditioning treatments. Shear bond strengths between the 4 resin cements and dentin also were measured. MATERIAL AND METHODS: Four hundred eighty discs (10 mm in diameter and 4 mm thick) of Ceramco II porcelain were randomly divided into 6 main groups (n = 80). The ceramic specimens received 6 different surface conditioning treatments before the application of resin cement. These surface treatments were sanding with 600-grit silicon carbide paper, microetching with aluminum oxide, sanding followed by silane application, microetching followed by silane application, hydrofluoric acid-etching, and hydrofluoric acid-etching followed by silane application. Each group then was subdivided into 4 subgroups (n = 20) for the application of 1 of 4 cements: Nexus, Panavia 21, RelyX ARC, and Calibra. All cemented specimens were tested under shear loading until fracture on a universal testing machine; the load at fracture was reported in MPa as the bond strength. Bond strengths were determined at 24 hours and after 6 months of specimen storage in a saline solution. For dentin-resin cement shear bond strength testing, dentin specimens were treated with dentin bonding agents, and a thin layer of resin cement was applied according to the manufacturer's directions. Prodigy composite was bonded to the cement. Shear bond strengths were determined as above and reported in MPa at fracture. Data were analyzed with 3-way analysis of variance (P<.01). RESULTS: Hydrofluoric acid-etching followed by silane application produced bond strengths (15.0 +/- 7.4 to 21.8 +/- 5.8 MPa) in the highest statistical group with all 4 cements at both 24 hours and 6 months (P<.01). Sanding with 600-grit silicon carbide paper and microetching with aluminum oxide produced the lowest bond strengths (0.0 to 4.0 +/- 3.5 MPa). At 24 hours and 6 months, there were no significant differences among the 4 cements when hydrofluoric acid-etching was followed by silane application. Both auto- and light-polymerized dentin bonding agents bonded better to dentin than dual-polymerized bonding agents. CONCLUSION: Within the limitations of this study, hydrofluoric acid-etching followed by silane application produced the best bonds at 24 hours and 6 months with all 4 cements. Auto- and light-polymerized adhesives were associated with higher bond strengths to dentin than dual-polymerized adhesives.

Acid Etching, Dental↗
PubMed2005

Interface evaluation after manual and ultrasonic insertion of standardized class I inlays using composite resin materials of different viscosity.

OBJECTIVE: The aim of the present study was to investigate the effect of manual and ultrasonic insertion of standardized class I inlays (Cerana) using three composite resin materials of different viscosity (Tetric Flow, Tetric, and Tetric Ceram) on time to seat inlays, film thickness, and filler distribution within the materials. METHODS: In a preliminary test, mean loads for manual and ultrasonic insertion were measured using the high viscosity composite resin material (Tetric Ceram). These loads were then applied with all composite resin materials to evaluate the times required to seat the inlays. In addition, film thickness was assessed using scanning electron microscopy, and filler distribution (wt% silicon, barium, ytterbium) was monitored using energy-dispersive spectroscopy. RESULTS: Ultrasonic insertion significantly reduced mean load applied to seat inlays (6.4+/-1.4 N; mean+/-SD) as compared to manual insertion (18.9+/-3.1 N; p < 0.001). Using an ultrasonic device, times for insertion values were significantly lower in the high and medium viscosity composite resin material groups compared to manual insertion (p < 0.05). The widest film thickness was recorded for the high viscosity composite resin material in combination with manual insertion (p < 0.05). However, when ultrasound was applied, there was no difference in film thickness between the three materials at any levels. Furthermore, the analysis of filler distribution revealed no significant differences between groups. CONCLUSION: Highly filled viscous composite resin materials may be used in combination with the ultrasonic insertion technique without untoward effects on film thickness or filler distribution.

Barium↗
PubMed2006

Evaluation of shear bond strength of microwaveable acrylic resins in denture repair: a comparative study.

OBJECTIVE: Acrylic denture base fracture is a common mode of failure. Heat-cured, auto-polymerized, visible light-cured, and microwaveable acrylic resins have been used as repair materials. The aim of this study was to evaluate the shear bond strength of two microwaveable resins (Acron MC and Justi) and one auto-polymerizing acrylic resin (ProBase Cold) as denture repair materials as opposed to a heat-cured one using the non-flasking procedure after thermocycling and photoaging. MATERIAL AND METHODS: Ninety cylindrical specimens were made using the Vertex Rapid Simplified heat-cured acrylic resin. Each repair acrylic resin was poured on the specimen's surface using a cylindrical rubber mold with an internal diameter of 8.5 mm. Thirty specimens for each repair material were made. The control group consisted of 10 specimens from each group which were stored in water for 24 h at 37 degrees C; another 10 specimens from each group were subjected to a thermocycling procedure (5-55 degrees C for 1,000 cycles), while the remaining 10 specimens were subjected to a photoaging procedure. Shear bond strength was measured on a universal testing machine and mode of bond failure was examined under a stereomicroscope. Two-way ANOVA and the Bonferroni post hoc test were performed to identify statistical differences at alpha = 0.05. RESULTS: Justi's shear bond values were significantly inferior to those of ProBase Cold (p <0.05) and Acron MC (p <0.05). ProBase Cold and Acron MC acrylic resins exhibited similar values (p >0.05) of shear bond strength. Thermocycling and photoaging did not affect the shear bond values of any of the materials under investigation (p >0.05). CONCLUSIONS: ProBase Cold and Acron MC exhibited similar shear bond values. Justi repair material exhibited inferior bond strength compared with that of ProBase Cold and Acron MC. Aging procedures did not affect the bonding properties of any of the repair materials.

Acrylic Resins↗
PubMed2002

Safety assessment for hair-spray resins: risk assessment based on rodent inhalation studies.

The methods involved in the safety assessment of resins used in hair-spray products have received little peer review, or debate in the published literature, despite their widespread use, in both hairdressing salons and the home. The safety assessment for these resins currently involves determining the type of lung pathology that can be caused in animal inhalation exposure studies, and establishing the no-observable-effect level (NOEL) for these pathologies. The likely human consumer exposure is determined by techniques that model the simulated exposure under "in use" conditions. From these values it is then possible to derive the likely safety factors for human exposure. An important part of this process would be to recognize the intrinsic differences between rodents and humans in terms of the respiratory doses that each species experiences during inhalation exposures, for the purpose of the safety assessment. Interspecies scaling factors become necessary when comparing the exposure doses experienced by rats, compared to humans, because of basic differences between species in lung clearance rates and the alveolar area in the lungs. The rodent inhalation data and modeled human exposure to Resin 6965, a resin polymer that is based on vinyl acetate, has been used to calculate the safety factor for human consumer exposure to this resin, under a range of "in use" exposure conditions. The use of this safety assessment process clearly demonstrates that Resin 6965 is acceptable for human consumer exposure under the conditions considered in this risk assessment.

Animals↗
PubMed2003

A new approach for estimating the labile aluminium fraction in soil solutions, through batch experiments, using cationic (Amberlite IR 120) or non ionic (Amberlite XAD 2) resins.

Aluminium fractionation was tested on two types of resin. The first approach was based on the selective sorption of cationic forms on a strong cation exchange resin (Amberlite IR 120) which is commonly used. Using a defined contact time (1 hour) between solution and resin (batch technique) it was possible to obtain separation between different aluminium species. The second approach was based on the sorption of organic matter, especially complexes between organic matter and aluminium, onto a non ionic resin (Amberlite XAD 2), batch reactors containing the solution and the resin were stirred for 16 hours. Some tests were carried out to compare the different techniques using samples containing various complexing molecules (salicylic acid and purified commercial humic acid). Aluminium fractionation was then carried out on different soil solutions with the two different types of resin. Horizons A and S from acid brown soil under chestnut and Douglas fir were used in order to compare the influence of the type and the content of organic matter on the released aluminium forms. It appears that A layers release more total aluminium than the S ones but only a small part is in cationic forms. The S layer presents Al essentially under reactive cationic forms.

Adsorption↗
PubMed1997

Detection of resin acid compounds in airborne particulate generated from rosin used as a soldering flux.

Various uses of rosin and exposure to its resin acid constituents have been associated with dermal and pulmonary sensitization. Methodology is presented to detect resin acids common to rosin (such as abietic and dehydroabietic acid) found in aerosol from heated rosin flux. Air filtration, solvent filter extraction, and gas chromatography/mass spectrometry were used to provide qualitative and quantitative information on the resin acid content of aerosol produced during soldering with rosin flux. Abietic acid and dehydroabietic acid were identified and quantified in aerosol derived from heated rosin flux, in samples collected in the field and in laboratory generated samples. Other resin acids (including several apparently oxidized resin acids) were detected, but not quantified. Laboratory mass balance experiments using soldering temperatures and liquid rosin flux showed that much of the nonvolatile material originally present in unheated flux may be captured on a sampling filter following heating and aerosolization. The data presented suggest that resin acids are a major component (with regard to mass) of the airborne contaminants produced during soldering with rosin flux. Abietic acid was shown to be unstable on sampling filters held for a period of weeks, while dehydroabietic acid and total solvent-soluble material were not found to degrade under the same conditions. Rosin aerosol produced in the laboratory using a soldering iron and liquid rosin flux produced particles shown to be of respirable size using scanning electron microscopy.

Abietanes↗
PubMed1997

Polymerization shrinkage of restorative resins using laser and visible light curing.

OBJECTIVE: This in vitro investigation compared the amount of linear shrinkage that occurs when a light-cured composite resin is cured with a visible light source, and also with an argon laser. SUMMARY BACKGROUND DATA: When composite resins are light-cured, they undergo a certain degree of polymerization shrinkage, which can be clinically significant and affect the efficacy of the restoration. A new protocol utilizes laser curing instead of conventional visible light. METHODS: Two hybrid composite resins were used, Z100 and TPH-Spectrum. Dimensional change was measured in a linear direction, using a calibrated light-microscope. A total of 40 samples of composite resin was tested using two curing lights, and two hybrid composite resins, resulting in four groups of 10 samples (n = 10) each. According to manufacturer instructions, curing time for the laser was 10 sec, and for visible light was 40 sec. RESULTS: With TPH-Spectrum, the mean shrinkage with visible light was 0.583% compared to that with laser light which was 0.591%. With Z100, the mean shrinkage with visible light was 0.565%, compared to that with laser light which was 0.551%. CONCLUSIONS: There was no significant difference in amount of shrinkage of hybrid composite resins between using visible light or laser light. There was also no significant difference in shrinkage between the two hybrid composites for either light source.

Analysis of Variance↗
PubMed1985

Resin injection studies of the lumbar extradural space.

Two resin injection studies of the lumbar extradural space were performed to elucidate its size and shape. To counteract the lack of cerebrospinal fluid pressure in the cadaver, the subarachnoid space was filled with water. In group 1, the extradural injection of resin caused an immediate increase in subarachnoid pressure. The casts produced varied in thickness, but were situated predominantly in the dorsomedial and dorsolateral regions of the spinal canal. Thin anterior spread occurred in 40% of cases. In group 2, resin was injected to the subarachnoid space before the extradural injection of dyed resin. The resulting extradural casts were thinner than in group 1, but the distribution of resin was similar. The problems of interpreting resin casts are discussed in relation to the results obtained, with reasons for suggesting that the extradural space is only potential.

Aged↗
PubMed1995

Torsional bond strength and failure pattern of ceramic brackets bonded to composite resin laminate veneers.

The objectives of this study were to investigate the torsional bond strength of ceramic brackets bonded to composite resin veneer laminates and to human enamel. Microfilled resin veneers were bonded directly to prepared, etched bovine teeth embedded in epoxy resin. Brackets [Allure IV (NSB), Fascination, Starfire TMB, and Transcend 2000] were bonded to abraded, acid-etched resin veneers with a light-cured or a chemically-cured adhesive. Brackets were also bonded to human teeth with light-cured and chemically-cured adhesives for comparison purposes. After 24 hours storage in water, specimens were subjected to torsional stress and the maximum shear stress tau max, was calculated. The debonded brackets, the veneer, and enamel surfaces were examined under a stereomicroscope and a SEM to study the failure modes. Three-way ANOVA with a Tukey multiple comparisons test revealed significant differences in bond strengths among bracket types and bonding substrate at P = 0.05 level. Highest bond strength was observed in brackets with a combination of micromechanical retention and chemical adhesion. Significant interactions among bracket, substrate (enamel or resin) and mode of cure of adhesive were observed. Analysis of the failure pattern of brackets revealed adhesive and/or cohesive resin failures in all brackets studied, while cohesive bracket failures occurred in the single-crystal Starfire TMB bracket and the polycrystalline Transcend 2000 bracket. Debonding ceramic brackets under a steady torsional load caused no substrate surface alterations regardless of adhesive used.

Analysis of Variance↗
PubMedDate not supplied

An attempt to improve diagnostics of contact allergy due to epoxy resin systems. First results of the multicentre study EPOX 2002.

Epoxy resin systems (ERSs) are a frequent cause of occupational allergic contact dermatitis. Sensitization occurs not only to the resins, but also to hardeners and reactive diluents. However, only a fraction of the ERS components currently in use are available for patch testing. With the multicentre study EPOX 2002, we attempted to improve diagnostics in this field by patch testing with components currently used in ERSs. During the first study period (October 2002 to July 2003), in addition to commercially available ERS patch test substances, 16 study substances (1 resin, 9 hardeners and 6 reactive diluents) were patch tested in 70 patients with suspected contact allergy due to ERSs and 22 patients with a prior positive patch test reaction to epoxy resin (ER) in the standard series. Most frequently, allergic reactions to ER based on diglycidyl ether of bisphenol A and F were observed (55.2% and 43.7%, respectively). Agreement between positive reactions to both resins, which can be explained by immunological cross-sensitization and/or coexposure, was substantial [Cohen's kappa 0.65 (95% CI: 0.49-0.80)]. Among the reactive diluents, 1,6-hexanediol diglycidyl ether (1,6-HDDGE) and 1,4-butanediol diglycidyl ether (1,4-BDDGE) were the most frequent allergens, with 19.5% and 18.4% positive reactions, respectively. Although agreement between positive reactions to 1,6-HDDGE and 1,4-BDDGE was even better than with the 2 resins, the sample size is considered too small to decide reliably whether 1,6-HDDGE alone could serve as a marker allergen for both. Allergic reactions to p-tert-butylphenyl glycidyl ether and to phenyl glycidyl ether (PGE) occurred in 11.5% of the patients tested, with only moderate agreement. All patients positive to cresyl glycidyl ether (6.8%) also reacted to PGE. Of the hardeners tested, m-xylylene diamine was the most frequent allergen (13.8%), followed by isophorone diamine (5.7%). No reactions were observed to several substances, the test concentration of which may have been too low and will be increased in the future.

Adolescent↗
PubMed1994

The effect of etching time with Gluma 2000 conditioning solution on shear bond strength of a composite resin and on micromorphology of the enamel.

The purpose of this study was to assess the effect of etching time with Gluma 2000 conditioning agent on, first, the shear bond strength of composite resin to tooth enamel and, secondly, the micromorphology of the enamel. In the first part of the study flat enamel surfaces were prepared with 600-grit silicon carbide paper on 40 primary and 40 permanent teeth. Ten specimens of each group were etched for 15, 30, 60 or 120 seconds before applying bonding resin and restorative composite resin. After 24 hours' storage in water, the shear bond strength of each specimen was tested. Analysis of variance indicated a significant difference between the eight groups. However, the Student-Newman-Keuls test indicated that the only differences that were significant were the greater bond strengths of the 15-second primary tooth specimens compared with the 15- and 30-second permanent tooth specimens. In most cases the debonded specimens showed cohesive failure in resin close to the coupling interface. In the second part of the study the morphology of the enamel etching patterns in 96 other teeth was studied by scanning electron microscopy. The patterns were similar in primary and permanent teeth, and the longer the etching time the more pronounced was the pattern. The patterns produced in ground enamel were more uniform and predictable than those in pumiced enamel. Examination of bonded resin surfaces after dissolution of the teeth showed complete reproduction of the etched enamel surfaces, indicating excellent flow of the resin into the etched enamel.

Acid Etching, Dental↗
PubMed1989

A study of surfaces developed on composite resins in vivo during 4.5 years; observations by SEM.

In this study seven commercial composite resins, one experimental composite and one dental amalgam were investigated. These materials were inserted into the cavities of denture molar teeth in different patients. After clinical service for 3, 9, 12, 24 and 54 months the specimens were removed and observed by scanning electron microscopy. The wear patterns of the filling materials and their changes with continuing clinical service for 4.5 years suggest that the abrasive mechanism of conventional composite resin is as follows. The softer resin matrix is worn away and inorganic filler particles are exposed, thereafter they loosen and fall off. As this process proceeds the composite resin is worn away. This process continues with time. In the case of microfilled composite, the organic fillers and resin matrix are worn away at the same rate. After long-term clinical service some cracks could be seen on the wear surface between the organic filler agglomerates and the resin matrix.

Chemical Phenomena↗