Bond strengths of fluoride-releasing restorative materials

PURPOSE: To compare the shear bond strengths to dentin of four tooth-colored fluoride-releasing restorative materials that utilize different mechanisms of dentin-bonding. MATERIALS AND METHODS: Four materials were tested: a chemically-cured glass ionomer (Ketac-Fil); a light-cured resin-modified glass ionomer (Photac-Fil); a light-cured resin-modified glass ionomer in conjunction with a resin dentin-bonding agent (Vitremer); and a light-cured resin composite in conjunction with a resin dentin-bonding agent (Tetric). The enamel was removed from four sides of the twenty human noncarious extracted molars which had their roots embedded in acrylic blocks. Cylindrical samples of the materials were prepared in plastic molds and bonded to the dentin surface according to the manufacturers' instructions. After 24 hours of storage in a humidor, the samples were sheared with an Instron testing machine at a crosshead speed of 0.5 mm/minute. RESULTS: Statistical evaluation (ANOVA and Duncan's test) suggests that the fluoride-releasing resin composite material utilizing a resin dentin-bonding agent provided a significantly greater mean shear bond strength (16.5 MPa) after 24 hours storage than any of the selected glass ionomer materials. Of the three glass ionomer materials compared, the light-cured resin-modified material with a resin dentin-bonding agent provided a significantly greater mean shear bond strength (6.7 MPa) than the light-cured resin-modified material without a resin dentin-bonding agent (3.0 MPa) or the chemically-cured material (3.8 MPa).     

Increased apoptotic cells in bone marrow biopsies from patients with aplastic anaemia

PURPOSE: To evaluate the 2-year clinical performance of two polyacid-modified resin composites and two resin-modified glass ionomers in Class V carious cavities. MATERIALS AND METHODS: A total of 120 Class V cavities were selected and 30 cavities were restored with one of two resin-modified glass ionomer materials (Fuji II LC Improved and Vitremer) and two polyacid-modified resin composites (Dyract and Compoglass) in Class V carious cavities after 2 years. The restorations were clinically evaluated after 1 and 2 years using the USPHS criteria. RESULTS: One-year findings revealed a significant difference in color match between Vitremer and other materials (P < 0.05) and no significant difference was found for the other criteria. Two-year results indicated a significant difference between resin-modified glass ionomers and polyacid-modified resin composite materials. The difference between Compoglass and Dyract was not statistically significant whereas the difference between Vitremer and Fuji II LC was statistically significant. Caries was not recorded at any evaluation period.     

Dyes for caries detection influence sound dentin bond strength

This study evaluated the influence of caries-detection dyes on the in vitro tensile bond strength of adhesive materials to sound dentin. Caries-free human molars were ground to expose superficial dentin. Two dyes (a commercial 0.5% basic fuchsin in propylene glycol and Cari-D-Tect) were applied to sound dentin and rinsed. Subsequently, the dentin was etched with phosphoric acid (35%) and rinsed, leaving a moist dentin surface. The adhesive (Prime & Bond 2.0) was applied in two layers and light cured. A composite (TPH Spectrum), a compomer (Dyract), and a hybrid ionomer (Advance) were used to prepare the bond-strength specimens with a 3-mm-in-diameter bonding area. Control groups were made without use of dyes. Six specimens were prepared for each group. After 24 hours in distilled water, tensile bond strength (MPa) was measured using a testing machine. Analysis of variance was used to evaluate the data. Without dyes, bond strengths of TPH Spectrum and Dyract with Prime and Bond 2.0 were similar and both values were significantly (P < 0.05) higher than that of Advance with Prime & Bond 2.0. Dyes for caries detection reduced the bond strength of TPH Spectrum and Dyract but not Advance when used with Prime and Bond 2.0.     

The influence of the depth of substrate dentin surface and thickness of the current restorative samples on bond strength

The effect of sample thickness and dentin depth on bond strength of composite, compomer and resin modified glass ionomer have been investigated. The occlusal surfaces of 84 non carious human third molars were used for bonding. 4 subgroups were tested, superficial dentin with sample thickness 1 and 2 mm and deep dentin with sample thickness 1 and 2 mm respectively SBMP + /Z 100 composite showed 26 +/- 3.2, 22.3 +/- 4.5, 17 +/- 3.2 and 21.8 +/- 4.2 MPa shear bond strength to S. dentin 1 mm, deep dentin 1 and 2 mm and S. dentin 2 mm respectively. Compoglass reported 10.4 +/- 1.57, 9.1 +/- 2.3, 5.0 +/- 0.6 and 9.24 +/- 3.1 MPa while, Vitremer achieved 4.7 +/- 0.49, 3.2 +/- 0.39, 3.0 +/- 0.81 and 3.2 +/- 0.53 MPa. It is concluded that the highest bond strength can be achieved to superficial dentin in thickness or increments not more than 1 mm. And that both dentin depth and sample thickness might influence the quality of the bond to dentin with an effect that varies from one material to another depending upon the mechanism of bond of each material and its chemical composition.     

Marginal adaptation of resin-bonded light-cured glass ionomers in dentin cavities

PURPOSE: To investigate the marginal adaptation of resin-modified glass ionomer cements in dentin cavities placed with or without additional application of resin bonding systems. MATERIALS AND METHODS: Three resin-modified materials (Fuji II LC, Photac-Fil, Vitremer), one compomer (Dyract) and as reference an adhesively bonded resin composite system (Gluma CPS-Pekafill) were used. Flat peripheral dentin surfaces on human molar teeth were produced by wet grinding on SiC paper. Cylindrical cavities, 3.5 mm wide, were prepared in these dentin areas and restored with the individual materials. Sixty cavities were pretreated and restored as requested by the respective manufacturers. Following water storage of the specimens for 15 minutes or 24 hours, excess was gently removed by wet grinding for microscopic inspection of the marginal area. Additionally, in 30 cavities an experimental one-component adhesive resin system, a proprietary dimethacrylate and HEMA mixture dissolved in acetone, was combined with each of the restoratives for evaluation after 15-minutes water storage. Finally, in six cavities each, Dyract was combined with Prime and Bond 2.0, and Vitremer with Scotchbond Multi-Purpose Plus for assessment after 15 minutes. Maximum marginal gap widths (MGW) were measured. One-way ANOVA by ranks (Kruskal-Wallis-Test) followed by Wilcoxon's Two-Sample test were used to study the statistical difference of MGW among the treatment groups at a rejection level P = 0.05. RESULTS: Neither the conventionally placed material systems nor the restorations in combination with adhesives showed consistently gap-free margins after 15-minute water storage. After 24-hour storage with Vitremer 4 of the 6 restorations were gap-free, whereas with all other materials only perfect margins were registered. There was, however, no significant difference between the groups. Application of the experimental and/or the specific resin bonding agents had no effect on early MGW except for the Photac-Fil group, which was significantly reduced.     

Protocols for the care of external fixator pin sites

The pre-cooperative or handicapped child with decay presents a special challenge to the practitioner and may require sedation or general anesthesia. Treatment with an interim restoration may delay treatment until the child is more mature and can accept dental treatment and is a more conservative approach than sedation, extractions or general anesthesia. Glass ionomer materials have been utilized for this application, but little is known about their retention to carious dentin. The purpose of this study was to determine whether the presence of artificial dentin decay will affect the shear bond strength of two light-cured glass ionomer materials. VariGlass and Vitrebond glass ionomer materials were attached to carious and non-carious primary dentin surfaces and bond strengths determined. There were no significant differences in shear bond strengths between the decayed and non-decayed surfaces [p < or = .001]. VariGlass had higher shear bond strengths than Vitrebond only after a pre-treatment with the PAA containing liquid. Pre-treatment with the liquid provided with each light-cured glass ionomer was beneficial in all instances except for Vitrebond on non-decayed surfaces.     

Effect of peroxide bleaches on fluoride release of dental materials

PURPOSE: To investigate the effect of two bleaching agents, 35% hydrogen peroxide (Superoxal) and 10% carbamide peroxide (Opalescence), on the release of fluoride from Ketac-Fil, a glass ionomer cement, Photac-Fil, a glass ionomer/resin hybrid; and Tetric, a resin composite with fluoride. MATERIALS AND METHODS: Seven disks (9 x 3 mm) of each material were immersed in Superoxal for 1 hour to simulate an in-office application; seven other disks of each material were immersed in Opalescence 1 hour daily for 7 days to simulate a week of home bleaching regimen; and seven additional disks of each material without bleach served as a control. The disks were kept in deionized water and the water was tested for fluoride released every 24 hours for 14, 21, 28, and 35 days, respectively. RESULTS: Repeated measures ANOVA showed that the mean daily release of fluoride did not differ significantly (P > 0.05) between the bleaching agents or the control: Superoxal 6.17 ppm, Opalescence 6.45 ppm, and control 6.50 ppm. Statistically significant differences (P < 0.05) occurred for mean daily fluoride (+/- standard error) released from the three materials over the 35-day period: Photac-Fil 12.31 +/- 0.48 ppm > Ketac-Fil 7.07 +/- 0.66 ppm > Tetric 0.12 +/- 0.01 ppm, respectively.     

Bonding of hybrid ionomers and resin cements to modified orthodontic band materials

Orthodontic bands often fail clinically at the band-cement interface. Hybrid ionomer and resin cements and a glass ionomer control were bonded to photo-etched and standard band materials, both of which were tested in as-received and air-abraded conditions. Cements were placed in a 3 mm diameter mold at the bonding interface and bonded to 6 x 6 mm stainless steel band specimens mounted to acrylic blocks. Specimens were stored in water for 24 hours at 37 degreesC and debonded in tension on a testing machine at 0.05 cm/minutes. Bond strengths (MPa) were calculated and data were analyzed by analysis of variance. Bond strengths to as-received bands were less than 3.4 MPa for cements tested, whereas bond strengths to air-abraded bands ranged from 7.1 to 17.7 MPa, except for the glass ionomer control. Air abrasion of band materials provides highly increased bond strength of hybrid ionomer and resin cements.     

Resin-modified glass ionomers for luting posterior ceramic restorations

OBJECTIVES: Until recently, esthetic inlay restorations in posterior teeth have been limited to cavities surrounded by enamel. Dentin adhesive systems in combination with luting composites and light-cured resin-modified glass ionomer cements offer a possibility for bonding ceramic inlays to cavities when the cervical margin is in dentin. This study was designed to compare in vitro marginal integrity of ceramic inlays bonded to dentin to restorations placed in cavities with margins located entirely in the enamel. METHODS: In the present in vitro study, the sealing abilities of a dentin bonding agent/luting composite combination (Syntac/Dual Cement, Vivadent) and resin-modified glass ionomers (Photac Fil, Photac Bond, ESPE; Dyract, De Trey Dentsply; Fuji II LC, GC Dental Industrial Corp.; and Vitremer, 3M Dental Products) used as luting agents in cavities extending beyond the cemento-enamel junction, were compared to the sealing abilities of a conventional luting composite (Vita Cerec Duo Cement, Vita) in cavities within sound enamel. SEM analysis and dye penetration were performed to evaluate marginal integrity at the cervical cavity margins. RESULTS: The dentin bonding agent/luting composite combination (Syntac/Dual Cement) rendered a marginal seal within the dentin similar to the quality obtained with the conventional luting procedures within sound enamel. When three out of the five resin-modified glass ionomers were used as luting agents (Dyract, Fuji II LC and Vitremer), the results were comparable to those reported for the dentin bonding agents and the conventional method. SIGNIFICANCE: Light-cured resin-modified glass ionomer cements may be considered as an alternative to dentin bonding agents when the cavity margins of ceramic inlay restorations are within the dentin. However, further studies, e.g., wear resistance, must be performed.     

Accelerated evolution and molecular surface of venom phospholipase A2 enzymes

The objective of this study was to determine the in vitro shear bond strength (in megapascals) and location of bond failure with two light-cured glass ionomer resin systems. One system was a hybrid glass ionomer cement with resin (GC Orthodontics, Aslip, Ill), and the other system a glass-filled resin system (Reliance Orthodontic Products, Inc, Itasca, Ill). These systems, Fuji Ortho LC (GC Orthodontics) and Ultra Band Lok (Reliance), respectively, were compared to a light-cured composite resin. Maxillary premolar brackets (n = 200) were bonded to the facial surface of human premolar teeth. The two glass ionomer resin systems were each evaluated by two protocols, one according to the manufacturers' direction plus a variation of their respective technique. The five distinct groups (n = 40) were stored in 37 degreesC distilled water for 30 days and subjected to thermocycling before shear bond strength testing. The findings indicated that large variations existed between the bond strengths of the materials tested. The laboratory shear bond strength of the glass-filled resin glass ionomer cement (Reliance), whether tested in a dry or moist field, was similar to the composite control with all of the previous materials being significantly (P <.01) higher than both the hybrid glass ionomer cement groups (Fuji Ortho LC). However, the hybrid glass ionomer cement with enamel conditioner demonstrated a clinically acceptable mean megapascal value. The Adhesive Remnant Index values ranged from 0.53 to 1.62. The hybrid glass ionomer cement without enamel conditioning recorded the lowest mean adhesive remnant index score and the lowest mean megapascal score. Although both products are glass ionomer resin systems, their individual chemistries vary; this affects their clinical performance. Clinically, it may be suggested that glass ionomers used in a dry field may be beneficial for orthodontic bonding, and that glass ionomer resin systems used in a moist environment need an enamel conditioner.     

Stimulation of cyclic adenosine monophosphate formation by the novel vasorelaxant peptide adrenomedullin in cultured rat mesangial cells

This study was conducted to compare the tensile bond strength at the two interfaces of the "sandwich technique". 48 hours after the specimens were tested, using Hounsfield tensometer. Load was gradually applied on to the specimen till the bond at the interface failed. The load at which the bond failed was recorded and analysed for statistical significance. From the present study it can be concluded that the bond between glass ionomer and dentine is better than the bond between glass ionomer and composite resin.     

Effects of N-methacryloyl amino acid applications on hybrid layer formation at the interface of intertubular dentin

To understand the role of NMAA in the bonding of composite resin to a dentin surface, we investigated the effects of N-methacryloyl amino acid (NMAA) application on the expansion of aggregated collagen fibers, formation of a hybrid layer, and the tensile bond strength between composite resin and dentin. Four NMAA derivatives--N-methacryloyl-alpha-glycine (NMGly), N-methacryloyl-gamma-amino n-butyric acid (NMBu), N-methacryloyl-alpha-hydroxyproline (NMHPro), and N-methacryloyl-alpha-glutamic acid (NMGlu)--were prepared and applied to dentin surfaces which had been etched with 40% by mass H3PO4 and air-blown. The shrunken collagenous layer expanded by approximately 50% to 70% by volume of the original collagenous layer thickness after application of the NMAA primers. Application of the bonding agent and composite resin after NMAA treatment resulted in the formation of a hybrid layer. The thickness of the hybrid layer was somewhat smaller than the collagenous layer formed by the NMAA treatment only, regardless of the type of NMAA used. The thickness of the hybrid layer was approximately ten times larger than that formed without NMAA treatment. Although all NMAA primers formed hybrid layers of similar thickness, higher tensile bond strengths, from 13 to 15 MPa, were obtained when etched and air-blown dentin was treated with NMBu, NMGly, or NMGlu. NMHPro gave only 6.6 MPa, a value similar to that obtained when no NMAA was used. We concluded, therefore, that formation of the hybrid layer is a necessary but insufficient condition for high bond strength.     

Bond strength and interfacial morphology of adhesives to primary teeth dentin

PURPOSES: To evaluate (1) the shear bond strength to the dentin of primary teeth and failure site of hydrophilic dentin bonding agents, (2) the interfacial micromorphology of these adhesives on primary teeth. MATERIALS AND METHODS: Seventy-six primary noncarious molars stored in distilled water were obtained. The teeth were cleaned with pumice and a rubber cup. The mesio-buccal surface of the teeth was ground flat with hand pressure with a series of SiC paper ending with the 600 grit to provide a uniform surface on superficial dentin to which the adhesives and resin composite could be applied. After preparing the dentin surface, the teeth were stored in distilled water for 48 hours. They were then rinsed and dried with compressed air and divided at random into four groups of 16 specimens each: Group 1: Dentastic; Group 2: One-Step; Group 3: Prime & Bond 2.0; Group 4: Compoglass SCA. Z100 resin was used in all groups. All specimens were thermocycled (500x) and sheared in an Instron machine. After shear testing, the debonding sites of all samples were examined with a stereomicroscope and selected samples were also examined with the scanning electron microscope. Three additional samples per group were used to evaluate the resin adaptation to dentin. RESULTS: The results in MPa were: Dentastic 19.62 (4.67); One-Step 11.24 (3.67), Prime & Bond 22.38 (6.47), Compoglass SCA 18.88 (4.04). ANOVA (P < 0.0001) revealed that there was a significant difference between the groups. The Student-Newman-Keuls test (P < 0.05) showed no statistically significant difference between Dentastic, Prime & Bond and Compoglass SCA. However, these three groups were statistically significantly higher than One Step. In the Dentastic group, 14 of 16 samples revealed resin cohesive failure (resin fracture) while two of 16 displayed dentin cohesive failure (dentin fracture). In the One Step group, 15 samples failed at the resin and one sample showed dentin cohesive failure. In the Prime & Bond group, 12 specimens revealed resin cohesive failure while four displayed dentin cohesive failure. In the Compoglass SCA group, 13 samples had resin cohesive failures while three had dentin cohesive failures. All samples revealed an intimate adaptation to the dentin displaying resin tag formation.     

The effect of air abrasion on shear bond strength to dentin with dental adhesives

This study compared the effects of different dentin surface treatments on the shear bond strengths of three adhesive systems. The adhesive systems included a resin-modified glass ionomer, Fuji II LC, and two dentin bonding systems, One Step and Scotchbond Multi-Purpose Plus. The surface treatments compared for each adhesive system were as follows: 1) the controls, which were conditioned, 2) air abrasion at 120 psi without conditioning, 3) air abrasion at 160 psi without conditioning, 4) air abrasion at 120 psi with conditioning, and 5) air abrasion at 160 psi with conditioning. The KCP 1000 Whisperjet was used for all air-abrasive specimens. Controls for each adhesive material (Fuji II LC, One Step, Scotchbond Multi-Purpose Plus) were bonded using manufacturers' recommendations. Results showed that air abrasion significantly lowered bond strength of the resin-modified glass ionomer, conditioned or nonconditioned (P < 0.01). Air abrasion alone significantly lowered bond strengths of the dentin bonding agent systems (P < 0.01). However, air abrasion plus conditioning of the dentin surface resulted in bond strengths that were similar to the conditioned-only specimens (P < 0.01).     

Circadian rhythm of breath hydrogen in young women

PURPOSE: The retention forces of a newly developed compomer cement (Dyract Cem), a glass ionomer cement (Ketac Cem Aplicap), and a resin cement (F21) were examined. MATERIAL AND METHODS: Cemented cast gold crowns were removed along the path of insertion with a Zwick universal testing device. The impact of both a cured and a noncured additional bonding layer that were applied to the inner surface of the crowns was examined across the Dyract Cem group. RESULTS: The mean adhesive strength was measured at 2.36 +/- 0.69 N/mm2 in the Ketac Cem group, at 0.60 +/- 0.28 N/mm2 in the F21 group, and at 1.85 +/- 0.94 N/mm2 in the Dyract Cem group, respectively. The application of an additional bonding layer to the inner surface of the crowns did not significantly improve the retentive strength of Dyract Cem; the respective mean strengths were observed at 1.46 +/-0.33 N/mm2 for the uncured and at 1.70 +/- 0.76 N/mm2 for the cured bonding layers. CONCLUSIONS: Dyract Cem and Ketac Cem showed significantly higher retentive strengths than F21 (p < 0.001, Wilcoxon test, 5% level). No significant difference was found in bond strength between Ketac Cem and Dyract Cem.     

A procedure for preparing undecalcified and unembedded bone sections for light microscopy

Recently, new restoratives, such as resin-modified glass ionomer cements (RMGIC) and polyacid-modified resin composites (PMC) were introduced for class III and class V cavities. Both materials use simplified cavity conditioning methods. The well-established treatment of enamel with phosphoric acid has been replaced with treatment using weaker acids. The purpose of this study was to investigate in vivo the quality and durability of the marginal bond to enamel of these restorative system and compare it with a resin composite restorative, Seventeen patients received class III restorations of each of the three restoratives. At baseline and after 1 year replica impressions were made for investigation of the vestibular margins with the scanning electron microscope. Semi-quantitative analysis of the enamel-restorative interfaces was performed at x200 and x1000 magnifications. The three restorative systems showed good marginal adaptation and high percentages of the length of the margins investigated at baseline were gap-free (82%-92%). The resin composite showed significantly better adaptation than the other materials. The marginal quality decreased significantly after 1 year for the resin composite and the polyacid-modified resin composite. The RMGIC showed improved sealing after 1 year in vivo, probably due to continuing water uptake. The percentages of gap-free margins of the total marginal length observed at 1 year were 73%, 90%, and 84%, respectively, for the PMC, the RMGIC and the resin composite. The difference between the PMC and the RMGIC was significant. In conclusion, a good marginal quality was seen for all three restorative systems in class III cavities after a period of 1 year.     

Clinical comparison between a glass ionomer cement and a composite for direct bonding of orthodontic brackets

The clinical performance of a glass ionomer cement for direct bonding of orthodontic brackets was compared with a composite resin routinely used in this procedure. Brackets were bonded, using both materials, in alternate quadrants of 16 patients of the Orthodontic Clinic of the State University of Rio de Janeiro. A total of 225 teeth, 112 in the glass ionomer cement group and 113 in the composite group, were tested. Bond failure frequencies were recorded for 12 months, and chi-square statistical test was carried out comparing the failure rates of the materials. The composite showed a statistically significant lower failure rate (7.96%) than the glass ionomer cement (50.89%), regardless of the dental arch tested. Although the glass ionomer cement presents important properties not observed in the composite, it is necessary to increase its cohesive strength to permit its clinical use for direct bonding of orthodontic brackets.     

Snow on cholera--the special lecture in the Second British Epidemiology and Public Health Course at Kansai Systems Laboratory on 24 August 1996

The purpose of this study was to evaluate the resin-dentin interfacial morphology and shear bond strength of several new and experimental dentin bonding systems classified as single-bottle/total etch, multi-step/total etch, and self-etching. Class 1 and 5 cavities were prepared from freshly extracted permanent molars and restored with composite resin. Each bonded sample was cross sectioned and one-half was completely demineralized and deproteinized, while the other half was polished along the cut surface to permit measurement of the thickness of resin-infiltrated dentin layer (RIDL) within intertubular dentin (iRIDL) and around the peritubular walls (pRIDL) of resin tags by SEM. Shear bond strength was measured for all the systems 2 minutes after photocuring. SEM showed iRIDL and resin tags of different morphology depending on material and dentin location. The iRIDL was thinner in superficial dentin and thicker in deep dentin. Peritubular RIDL (pRIDL) was thinner than intertubular RIDL. Bond strength measurements varied from 12 to 21 MPa, depending on the materials used. Self-etching primer systems exhibited the highest bond strength, although one of the one-step/total etch systems also yielded very high values. The contribution of pRIDL to adhesion onto superficial dentin is limited by the small number of tubules. Single-component bonding agents produced SEM morphology and bond strengths similar to those of multi-step systems. Self-etching systems, despite their limited RIDL thickness, produced the highest immediate bond strengths. Bond strength did not correlate well with the thickness and morphology of RIDL.     

The effect of dentin primer on the tensile bond strength to human enamel

Four third-generation dentin bonding products (Scotchbond Multi-Purpose, Optibond, All-Bond 2, and Prisma Universal Bond 3) were tested to evaluate their tensile bond strength to enamel. Test enamel specimens were etched, primed, and polymerized according to each manufacturer's directions. Control specimens were treated identically except the primer application was eliminated. The results demonstrated that the dentin primer significantly increased the tensile bond strength of All-Bond 2, significantly decreased the tensile bond strength of Scotchbond Multi-Purpose and Optibond, and had no significant effect for Prisma Universal Bond 3. A one-way analysis of variance was run between the eight groups tested, and three significant subsets were found (P < .05). The subset with the highest mean tensile bond strengths consisted of Prisma Universal Bond 3 primed and nonprimed, All-Bond 2 primed, and Optibond nonprimed.     

Starch utilization by Bacteroides ovatus isolated from the human large intestine

OBJECTIVE: It was hypothesized that there is an inverse relationship between resin-enamel bond strength and bonded cross-sectional area, and that there are regional differences in resin-enamel bond strength. METHODS: The facial and lingual surfaces of extracted human third molars were ground down 0.3 mm using 240 grit abrasive paper and were then bonded with either Clearfil Liner Bond 2 or Scotchbond Multi-Purpose Plus adhesive systems using the manufacturer's instructions. The bonded surfaces then received a resin composite build-up. After 24 h of storage in water, the bonded teeth were vertically serially sectioned into 1.0 mm thick slabs using a diamond saw, and the bonded surface area at the resin-enamel interface was varied from 0.5 to 3.0 mm2 using a diamond saw under microscopic observation. The trimmed region was varied from the occlusal third of the facial or lingual enamel to the middle third, to the cervical third. The trimmed specimens were then glued to a Bencor Multi-T device, placed in an Instron testing machine and stressed to failure at 1 mm/min. A three-factor ANOVA was used to compare bond strengths (buccal vs. lingual, occlusal vs. middle vs. cervical-third, vs. materials). Regression analysis was used to examine the relationship between bond strength and bonded cross-sectional area for each material on occlusal enamel. RESULTS: For both bonding systems, there was a highly significant (p < 0.001) inverse exponential relationship between tensile bond strength (y axis) and bonded cross-sectional area (x axis) with y intercepts of 51 and 59 MPa for Clearfill Liner Bond 2 and Multi-Purpose Plus, respectively. Using both materials, the highest bond strengths were measured in the occlusal third, which were significantly higher (p < 0.05) than those made to cervical enamel. SIGNIFICANCE: Like resin-dentin bonds, resin-enamel bonds exhibit an inverse relationship with cross-sectional area. This relationship becomes more apparent at bonded surface areas below 2 mm2 and is probably due to reductions in the number of interfacial stress-raisers as samples are made smaller.