Etched Enamel Surfaces Research Articles

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.

A scanning electron-microscopic study of in vitro abrasion of mammalian tooth enamel under compressive loads

Microscopic tooth-wear (microwear) patterns can be an important tool for assessing modes and rates of abrasive tooth wear, but their analysis and interpretation is complicated by the fact that microwear is influenced by many factors. Three of these factors were here tested under conditions of compressive loading: (1) species differences in enamel structure, (2) abrasive particle size and (3) magnitude of force. Teeth of four species ( Homo sapiens, Lemur fulvus, Ovis aries and Crocodylus rhombifer) were abraded in vitro using three sizes of abrasive silicon-carbide grit (average diameters 73, 23 and 14 μm), at two loads (50 and 100 kg). Microwear features were assessed by scanning electron microscopy of lightly etched enamel surfaces and epoxy replicas. Microwear pits (length: width < 4:1) were the predominant feature type. Factorial analysis of variance of rank-transformed, feature-area measurements demonstrated that, under conditions of compressive loading, the size of abrasive particles was the primary determinant of microwear size. These results contrast with previous experimental tests of abrasion by predominantly shearing loads, where feature size was influenced by interaction among experimental factors, including the microscopic orientation of enamel crystallites. Although magnitude of compressive force was not a factor in microwear size variation, it may be a critical factor in explaining the presence or absence of microwear on tooth surfaces. The relatively small compressive bite force generated during typical chewing may not consistently produce abrasive pitting. These experiments demonstrate that, as the same abrasive regime can produce both large and small pits, the mechanism by which wear features are formed (i.e. compression or adhesion) cannot be determined from the size of features alone. Nevertheless, the dependence of pit size on abrasive particle size demonstrates that metrical variation in wear features can elucidate important attributes of an animal's diet.

Shear resistance of composite resin to enamel using color-modifying resins and variously applied unfilled bonding resins

The effects of bond layer thickness of color-modifying resins and variously applied unfilled resins on composite resin/enamel shear bond strengths were compared. Composite resin columns were bonded to etched enamel surfaces in vitro with either applied unfilled resins or with filled color-modifying resins. The bond layer thickness and the force required to shear the 17 specimens of each of six groups were measured. ANOVA with Tukey's test was performed to determine if significant differences at the α = 0.05 level existed for the mean bond layer thicknesses as well as the mean forces required to debond the specimens of six groups. Color modifying resins resulted in a 5 to 327 times greater bond thickness than the unfilled resins. Only one of the unfilled resin groups showed a statistically significant difference in shear resistance compared with a color-modifying resin group. The method of application and resulting thickness of unfilled resin appeared to have little effect on composite resin/enamel shear bond strengths.

Use of a modified rubber dam technique when bonding resin-retained fixed partial dentures

The use of rubber dam isolation is an important step when bonding a resin-retained fixed partial denture (FPD).’ Failure to use a rubber dam may contribute to failure of the resin-retained FPD.2 Without a rubber dam, moisture control is difficult and the etched enamel surfaces may be contaminated by moisture from the patient’s breath. A rubber dam placed with conventional techniques must be stretched over the pontic tissue. This adaptation inhibits passive seating of the FPD and can prevent complete seating in the area of the pontic. This article describes a modified rubber dam technique that isolates the teeth, yet allows complete and passive seating of the resin-retained FPD during cementation. 4. Place the rubber dam clamps on the teeth adjacent to the FPD. With the rubber dam stretched on the frame, slip the rubber dam over the retainers and under the buccal and lingual wings of the clamps. 5. If necessary, insert cotton rolls under the rubber dam buccally or lingually for added moisture control. The abutment teeth are now isolated and are ready to be etched. The FPD can be bonded without resistance from the rubber dam in the pontic area (Figs. 1 and 2). After the bonding material has set, the incisal seating‘ hooks on the abutment teeth are removed by using a highspeed drill with a copious amount of water spray to keep the framework ~001.~ The rubber dam is then removed.

Effects of saliva contamination and phosphoric acid composition on bond strength

The purpose of this study was to determine the effects of a phosphoric acid gel and solution, and saliva contamination of etched enamel on the tensile bond strength (TBS) of a posterior composite resin to etched enamel. Ninety-six extracted human permanent maxillary canines were used in this study. The test system developed by Kemper and Kilian was used to determine the TBS of a posterior composite resin (P-10) to enamel. The ground enamel surfaces were etched with 37% H 3PO 4 gel for 60 sec and washed for 15 sec or 30 sec, and with 37% H 3PO 4 solution for 60 sec and washed for 15 sec or 30 sec, respectively. The ground enamel surfaces were also etched with H 3PO 4 gel for 60 sec, washed for 15 sec and rewashed for 15 sec after saliva contamination of the etched enamel for 15 sec, 60 sec and 60 min, respectively. Etched enamel surfaces contaminated with saliva for 15 sec were re-etched for 15 sec and washed for 15 sec. The test specimens were mounted in an Instron machine and subjected to a tensile load at 0.02 inch. min −1. The force required to break a test specimen was recorded, and the bond strengths were calculated and expressed in MN.m −2. The data were analyzed by ANOVA and Duncan's multiple range test at the 5% level of significance. The H 3PO 4 composition (gel vs solution) and wash times had no significantly different effect on TBS. Only a 60 min saliva contamination significantly reduced TBS. In this study the TBS was determined 24 h after specimen preparation. It is possible that salivary contamination of etched enamel may have an adverse effect on bond strength only after prolonged immersion of the test specimens prior to testing.

A clinical study of the composite/bonding resin-tooth interface

Intermediary low viscosity bonding resins (LVBR) were introduced for application to etched enamel surfaces prior to the placement of conventional composite restorative ressins. The results of recent in vitro studies suggested that the use of a LVBR was not necessary. The purpose of this clinical study was to evaluate the effects of a LVBR on the clinical performance of conventional composite restorations. Sixty-five subjects with at least 2 Class III or V lesions located on the maxillary permanent anterior teeth participated in the study. Preoperative photographs of the lesions were taken. A LVBR was applied to the etched enamel walls of a randomly selected preparation prior to restorations with a composite resin, while the paired restoration was placed without the use of a LVBR. Final finishing of the restorations was delayed for 48 h after which postoperative photographs were obtained. Impressions of the restorations were taken, and replicas, prepared with epoxy resin, were examined using the SEM. The subjects were recalled 18 months after the placement of the restorations. Photographs and replicas were made at the recall visit. The following criteria were evaluated at recall: cavosurface marginal discoloration, anatomic form, occurrence of secondary caries, and marginal adaptation (from SEM photomicrographs). The rating scales defined by Ryge (1980) were used. Although differences were observed between the paired restorations, these were not significant. Both restorative procedures resulted in clinically acceptable restorations.

Tensile bond strengths of resin luting cements for resin-bonded bridges to etched enamel

Resin luting cements for resin-bonded bridges have recently been introduced. The objective of this study was to evaluate the tensile bond strengths of 6 new resin cements to etched enamel surfaces of freshly extracted human molar and premolar teeth. Tensile bond strengths ranged between 11.98 ±1.91 MN.m −2 and 15.26±5.52 MN.m −2. There were no statistically significant differences (p>0.05) between the lowest and highest values recorded for tensile bond strengths of the different cements included in this study.

The influence of environmental temperature, humidity and methods to dry the etched enamel surface on the adhesive strength of dental adhesive resin 'Panavia EX'

The purpose of this study was to evaluate the influence of environmental temperature, humidity and methods to dry the etched enamel surface on the adhesive strength of dental adhesive resin ‘Panavia EX’. The findings were as follows:1. Though temperature and humidity in oral cavity were higher than 30°C and 81% respectively, they were significantly different from site to site.2. By rubber dam application, temperature and humidity in oral cavity decreased markedly. By sucking air with vacuum in addition to rubber dam application, both decreased still more.3. When vacuum was used, there were no statistically significant differences in temperature and humidity among applications of rubber dum, mini-dam, and cotton roll with clamp.4. The higher were both of environmental temperature and humidity, the more was the tensile adhesive strength reduced. However, since the adhesive strength was not influenced singly by temperature or by humidity, it is suggested that the adhesive strength is influenced by absolute moisture volume.5. Drying time on the etched-enamel surface influenced the adhesive strength significantly whatever environmental temperature and humidity are. It seems that at least 15 seconds are needed to dry the etched-enamel surface sufficiently with air syringe.6. It was hardly effective for increasing the adhesive strength to dry the etched-enamel surface with alcohol and to increase the temperature and pressure of compressed air.

A laboratory evaluation of three etching solutions.

Abstract Solutions containing 50 m/m % phosphoric acid (A), 25 m/m % pyruvic acid (B), and 50 m/m % citric acid (C) were prepared. The tensile bond strenghs of a conventional chemically activated composite resin (Concise) and a sealant (Delton) to enamel surfaces etched with the respective etching agents were determined. The surface roughness (RA) of polished enamel surfaces etched with the respective acids was measured and the effects on the morphology of polished etched enamel surfaces evaluated by SEM. The tensile bond strengths expressed in MN.m−2 were: Concise: Etched with A=15.2± 3.5; B=19.1±3.1;C=10.7±1.8. Delton: Etched with A=13.5±2.9; B =18.6±4.7; C=8.4±1.4. Pyruvic acid etching produced significantly greater bond strengths than phosphoric acid etching which in turn produced significantly greater bond strengths than citric acid. RA values in μm were: A= 0.31±0.07; B=0.33±0.05; C=0.17±0.03. Phosphoric acid and pyruvic acid etching of polished enamel surfaces produced well-defined etching patterns.

The effect of fluoride in phosphoric acid on enamel fluoride uptake and the tensile bond strength of an orthodontic bonding resin

Decalcification that occurs adjacent to bonded orthodontic brackets is of great concern to orthodontists. Among the many procedures suggested to overcome this problem is the addition of fluoride to the phosphoric acid (H 3PO 4,) etching solution. The purposes of this study were to determine the loss of fluoride from the acidic etching solutions, to evaluate the effect of various fluoride concentrations in H 3PO 4, on the tensile bond strength of an orthodontic bonding resin, to determine the amount of total and bound fluoride acquired by etched enamel, and to evaluate the effect of these etching solutions on enamel by scanning electron microscopy. Solutions of 50 m/m% H 3PO 4 containing 0 and approximately 0.01, 0.04, 0.08, 0.2, 0.4 and 0.9% fluoride were prepared. The fluoride concentrations in the etching solutions remained stable up to 3 months after preparation. The tensile bond strengths of the bonding resin to the etched enamel surfaces were not significantly different. Enamel acquired the greatest amount of total fluoride from H 3PO 4 solutions containing 0.215% fluoride while the bound fluoride acquired by enamel from the fluoride-containing etching solutions was not significantly different. The addition of fluoride to H 3PO 4 did not impede the etching effect on enamel.

The effect of topical fluoride treatment on enamel fluoride uptake and the tensile bond strength of an orthodontic bonding resin

Enamel demineralization occurring adjacent to directly bonded orthodontic attachments is of great concern to orthodontists. The topical application of fluorides to enamel surfaces before acid etching and the bonding of the attachments is not recommended by many investigators. The objective of this study was to determine the enamel fluoride acquired from various topical fluoride agents and to determine the effect of the acquired fluoride on the tensile bond strength of an orthodontic bonding system. Fifty extracted maxillary central incisors were mounted in cups and the facial surfaces of the crowns were polished on 600-grit silicon carbide paper. Enamel microbiopsies were performed just off the midpoint of each tooth. Ten teeth served as controls and received no topical fluoride treatment, while a similar number were treated with either APF, SnF2, Duraphat, or Fluor Protector. The teeth were suspended in synthetic saliva 4 minutes after fluoride application. The topical fluoride agents were removed after 24 hours and the teeth were again suspended in synthetic saliva at 37 °C for 7 days. Enamel biopsies were again performed just off the midpoint of each tooth on the side not previously biopsied. The enamel surfaces were etched for 1 minute and the tensile bond strength of Concise orthodontic bonding system to the etched enamel surfaces was determined. The enamel surfaces acquired significantly different amounts of fluoride from the topical fluoride agents, but the bond strengths to these surfaces were not significantly different. The results of this in vitro study suggest that the application of topical fluoride agents to enamel surfaces 7 days before the bonding of orthodontic attachments will not have an adverse effect on bond strength.

Oral fluid contamination of etched enamel surfaces: an SEM study

The purpose of this in vitro study was to determine the effects of differing salivary contamination periods on the surface topography of etched enamel surfaces using SEM techniques. The results indicated that salivary contamination of etched enamel for 1 second or longer resulted in the formation of surface coatings that could not be removed by a water wash. It was concluded that should salivary contamination of an etched enamel surface occur, it would be necessary to repeat the etching procedure to ensure adequate bonding of a resin material.

Composite and intermediate resin tag formation in acid-etched enamel: A scanning electron microscopy evaluation

A divergence of opinion exists regarding the efficacy of the use of an intermediate or unfilled resin in the acid-etch technique of restorative dentistry. For example, the manufacturers of Concise (3M Co., Dental Products Div., St. Paul, Minn.), Adaptic (Johnson and Johnson Dental Products Co., East Windsor, N.J.), and Silar (3M Co., Dental Products Div.) endorse the use of an intermediate resin, while Isopast (Vivadent [USA] Inc., Buffalo, N.Y.) is recommended by the manufacturer for use directly on the etched enamel surface. The main concerns are retention and sealing, which are directly related to the capacity of the resin to wet and thus adapt to the acid-etched enamel. In turn, a good indication of proper wettability is provided by the formation of resin tags in the etched enamel. The purpose of this study was to examine tag formation of selected composite and intermediate resins through the medium of scanning electron microscopy (SEM).

Effect of acid etching technics on the adhesion of composite resins applied to the enamel

The purpose of this study is to evaluate the generally accepted enamel etching procedure for the composite resin restoration and to develop a more useful one. The flat ground enamel surfaces of human teeth were treated with varying exposure period to various etchants and different washing pressures. The tensile bond strength of the adhesive resin applied to the enamel was determined. After testing, the enamel surface and the interfacial resin structure were observed by SEM. The bond strength would greatly depended upon the microfine irregularity resulting from the individual enamel crystal rather than much greater irregularity due to the preferential loss of prism periphery. The bond strength was remarkably reduced when the dissolution products deposited on the etched enamel surface. These products were generated by long etching with orthophosphoric acid solution or citric acid containing FeCl3. Compared with the acid solution, the gel-like liquid generally required a longer etching to produce such a microfine irregularity contributing to bonding. A new etching technique with two applications of the gel-like liquid for 5 seconds each succeeded in efficiently producing the microfine irregularity resulting in the marked increase of the bond strength. This double etching technique was found very practical for clinical use.

Retentiveness of enamel-resin bonds using unfilled and filled resins

The shear strength of composite resin from etched enamel surfaces was tested using five different techniques for placing composite resin and/or unfilled resin. The results did not show significant shear strength differences among the various methods of placing unfilled resins before filled resin or placing filled resin alone.

The Use of an Intermediate Resin in the Acid-etch Procedure: Retentive Strength, Microleakage, and Failure Mode Analysis

Three composite resin systems, one conventional (Concise) and two microfilled (IsoPast and Silar), used with and without an intermediate resin (Concise Enamel Bond), were evaluated with and without thermal stress for in vitro retentive strength and sealing ability to acid-etched human enamel. All three materials yielded significantly different shear strength values. The use of an intermediate resin significantly improved both the shear strength and resistance to microleakage of Silar, while no differences were observed for Concise and IsoPast. The thermocycling procedure did not generally or consistently affect the results. The failure mode of the three acid-etched composite resins was studied by evaluation of the failure surface and by describing the percentage of enamel, composite, and interface which were present. The use of an intermediate resin did not significantly influence the failure mode, and the correlation between the failure mode and retentive strength, although significant was low. The study confirmed the importance of adequate wetting action of a resin on the etched enamel to ensure proper bonding.

In vitro studies on susceptibility of enamel to caries attack after orthodontic bonding procedures

Oral hygiene plays an important role in the prevention of caries. Therefore, when one is investigating the possible effects of acid etching on caries susceptibility, oral hygiene aspects and the supplementation of fluoride have to be considered. The objective of this investigation was to study the caries suceptibility of etched enamel surfaces in vitro. To simulate the in vivo situation, much attention was given to the influence of remineralization of saliva and fluorides. It was shown that etching and subsequently fluoridating and remineralization increases resistance of enamel against a caries attack.

Enamel alterations from bracket bonding and debonding: a study with the scanning electron microscope.

The central problems of the direct-bonding technique were investigated with a comprehensive scanning electron microscope study. Labial surfaces of extracted teeth were etched for a study of enamel conditioning. Starting from the appearance of a 2-minute etching with 50 percent phosphoric acid, the influence of different factors on the etching patterns was investigated: variation of etching time, of acid concentration, and of acid dispersion; etching of fluoride-treated enamel; and variation of the rinsing time with the air/water syringe. Furthermore, the effect of contamination with saliva, mucosa, oil, and finger contact was demonstrated. The penetration depth of resin tags was measured by means of adhesive matrices and of cross sections through bracket/adhesive/enamel which were partially demineralized. The etching patterns generally were variable. On the same enamel surfaces, sparsely etched areas were found near zones that showed etching types with preferential dissolution of prism cores or prism peripheries and sometimes with poorly structured morphology. The findings of varying the etching time suggested that the peripheral etching pattern is an advanced state of acid attack, after fracturing or breaking down of the marginal ridges. A 2-minute etching with gel-like 50 percent phosphoric acid (H 3 PO 4 ) was found optimum to provide an equal distribution of retentive microroughnesses on the entire conditioned enamel surface. The water-spraying time that follows the etching process should not be less than 5 seconds per tooth in order that all superficial acid residues and crystal precipitates may be surely wiped off. The resin tags generally reached a depth of 80 μm, sometimes extending to about 100 to 170 μm in length. The repair procedures on etched enamel surfaces not covered by adhesive were investigated in vitro and in vivo. The repair is effected by defect-filling organic/inorganic precipitates from saliva and by grading. (brushing habits, abrasive foodstuffs, etc.). Even after a 4-month exposure of etched enamel surfaces in the mouth environment, no restitutio ad integrum was found. The etching lesion is still visible, sometimes showing a coblike surface structure. Examination of clinically and experimentally removed brackets revealed a heterogenous site of fracture, partially running along the bracket/adhesive interface, within the adhesive, partially along the adhesive/enamel interface, and within the enamel. The location of the fracture site depends on the strength of micromechanical retention produced by the acid pretreatment. Localized terraced or ribbed enamel tear-outs reached to a depth of 100 μm. The clinical consequences of the morphologic findings are discussed.

Is a low viscosity bonding resin necessary?

SummaryLow viscosity bonding resins have been introduced for use on etched enamel surfaces prior to the application of the viscous composite resins. In this in vitro study the effects of a low viscosity bonding resin on the bond strength, adaptation and microleakage of a composite resin to etched enamel were evaluated. The low viscosity bonding resin did not improve the tensile bond strength of a composite resin to etched enamel, did not increase resin penetration into etched enamel and did not decrease marginal leakage at the composite resin/etched enamel interface. The continued use of low viscosity bonding resins in clinical dentistry is questioned.

Problems with sealants for bracket bonding

The polymerization in thin films on smooth tooth surfaces was assessed for four conventional bonding and pit and fissure sealants and one new acetone-containing sealant. A routine bonding procedure was followed up to the stage of bracket placement. The sealants were allowed to polymerize buccally and lingually on forty-four premolars, which were then carefully extracted and analyzed clinically and in the stereomicroscope. For thirty-eight surfaces, a soluble ultraviolet dye (sodium fluorescein) was added to the universal resin, and these teeth were examined by fluorescence microscopy of ground sections. On the remaining fifty surfaces a chemical analysis of polymerized sealant was made after demineralization in 10 percent hydrochloric acid and included infrared spectroscopy, refractive index, and combined gas chromatography and mass spectrometry. The results demonstrated that, despite some individual variation, all four conventional sealants failed to produce a thin protective film to cover the entire etched enamel surfaces. This was mainly due to nonpolymerization caused by oxygen inhibition and to sealant flow before setting. The chemical analyses indicated a large amount of unreacted methacrylate groups where these sealants had polymerized. In contrast, the acetone-containing sealant polymerized to a thin film with less remaining methacrylate groups. The need for improved sealants for orthodontic bonding purposes was discussed.