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Endodontic sealers should demonstrate adhesive properties to dentin to reach the objectives of the obturation of the canal space and seal the canal space both apically and coronally, thus decreasing the chance of endodontic treatment failure. Adhesion to dentin with bonding to the tooth structure in the canal may provide greater resistance to tooth fracture and greater clinical longevity of an endodontically treated tooth. In this study, human single-canal canines were endodontically treated and obturated with two different endodontic obturation systems (Epiphany/Resilon system and gutta-percha/AH 26). Thirty roots (divided into two groups) were horizontally sliced for a push-out strength test, which was performed from apical to coronal in the universal testing machine. Differences in push-out bond strength between the two different material systems were obtained using repeated measures analysis of variance on ranks. Gutta-percha had significantly higher push-out bond strength than Epiphany (p<0.0001).

This study investigated the influence of thermal cycling on the dentin bond strengths of single-step self-etch adhesive systems. The Absolute, Clearfil Tri-S Bond, G-Bond and One-Up Bond F Plus systems were used. Bovine mandibular incisors were mounted in self-curing resin, and the facial surfaces were wet ground with #600 SiC paper. Adhesives were applied to the prepared dentin surfaces, and they were light irradiated according to each manufacturer's instructions. Resin composites were condensed into a mold (4 mm in diameter and 2 mm in height) and light irradiated for 30 seconds. Bonded specimens were divided into three groups and subjected to different storage conditions as follows: 37 degrees C water for 24 hours; 37 degrees C water for 24 hours followed by 10,000 thermal cycles between 5 degrees C and 60 degrees C or 37 degrees C water for 24 hours followed by 20,000 thermal cycles between 5 degrees C and 60 degrees C. Ten samples per group were tested in a shear mode at a crosshead speed of 1.0 mm/minute. Analysis of variance and Tukey's HSD test at the 0.05 significance level were used to compare the three storage conditions for each adhesive system. After 24 hours storage in water, the mean dentin bond strengths ranged from 11.4 MPa to 17.1 MPa. The Clearfil Tri-S Bond system showed the highest bond strength. After 10,000 thermal cycles, the mean bond strengths remained unchanged except for those of the Clearfil Tri-S Bond system, which significantly increased. Significant decreases in bond strength were observed for the Absolute and One-Up Bond F Plus systems after 20,000 thermal cycles. Failure mode was commonly due to adhesive breakdown associated with partial cohesive failure of the adhesive resin. From the results of this study, in terms of simplifying the clinical procedure, the benefit of using single-step self-etch systems might be acceptable.

This study investigated the influence of thermal cycling on the enamel bond strength of single-step self-etch adhesive systems. The systems used were Absolute, Clearfil tri-S Bond, G-Bond and One-Up Bond F Plus. Bovine mandibular incisors were mounted in self-curing resin, and the facial surfaces were wet ground with #600 SiC paper. Adhesives were applied on the prepared enamel surfaces and light irradiated according to each manufacturer's instructions. Resin composites were condensed into a mold (ø4x2 mm) and light irradiated for 30 seconds. Thirty specimens per adhesive systems were divided into 1 of 3 test groups (n=10) following storage in water at 37 degrees C for 24 hours. The specimens were then stored in 37 degrees C water for 24 hours, followed by thermal cycling 10,000 and 20,000 times between 5 degrees C and 60 degrees C. After each storage condition, the specimens were tested in shear mode at a crosshead speed of 1.0-mm/minute. One-way ANOVAs and Tukey HSD test at a level of 0.05 were conducted. After 24 hours of water storage, the mean enamel bond strengths ranged from 11.3 to 16.9 MPa, and Clearfil tri-S Bond showed significantly higher bond strength. After thermal cycling, the mean bond strengths ranged from 8.3 to 20.7 MPa. The changes in enamel bond strengths were different among the adhesive systems tested. Failure modes after the test were commonly adhesive failure associated with partial cohesive failure adhesive in resin. With a careful choice of adhesive systems, the benefit to using single-step self-etch systems in terms of simplifying the clinical procedure might be acceptable, even after thermal stresses.

This study examined the effect of air-drying time of adhesives on the dentin bond strength of several single-application self-etch adhesive systems. The adhesive/resin composite combinations used were: Adper Prompt L-Pop/Filtek Z250 (AP), Clearfil Tri-S Bond/Clearfil AP-X (CT), Fluoro Bond Shake One/Beautifil (FB), G-Bond/Gradia Direct (GB) and One-Up Bond F Plus/Palfique Estelite (OF). Bovine mandibular incisors were mounted in self-curing resin and wet ground with #600 SiC to expose labial dentin. Adhesives were applied according to each manufacturer's instructions followed by air-drying time for 0 (without air-drying), 5 and 10 seconds. After light irradiation of the adhesives, the resin composites were condensed into a mold (phi4x2 mm) and polymerized. Ten samples per test group were stored in 37 degrees C distilled water for 24 hours; they were then shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVA followed by Tukey's HSD tests (alpha = 0.05) were done. FE-SEM observations of the resin/dentin interface were also conducted. Dentin bond strength varied with the different air drying times and ranged from 5.8 +/- 2.4 to 13.9 +/- 2.8 MPa for AP, 4.9 +/- 1.5 to 17.1 +/- 2.3 MPa for CT, 7.9 +/- 2.8 to 13.8 +/- 2.4 MPa for FB, 3.7 +/- 1.4 to 13.4 +/- 1.2 MPa for GB and 4.6 +/- 2.1 to 13.7 +/- 2.6 MPa for OF. With longer air drying of adhesives, no significant changes in bond strengths were found for the systems used except for OF. Significantly lower bond strengths were obtained for the 10-second air-drying group for OF. From FE-SEM observations, gaps between the cured adhesive and resin composites were observed for the specimens without the air drying of adhesives except for OF. The data suggests that, with four of the single-application self-etch adhesive systems, air drying is essential to obtain adequate dentin bond strengths, but increased drying time does not significantly influence bond strength. For the other system studied, the bond strength of the non-air dried group was not significantly different from the five second drying time, but prolonged drying was very detrimental to bond strength. For all five of the systems studied, a five-second air-drying time appeared to be appropriate.

This study examined the relationship between delay in composite placement over cured adhesives and the dentin bond strength of several single-application self-etch adhesive systems. The adhesive system/resin composite combinations used were: Adper Prompt L-Pop/Filtek Z250 (AP), AQ Bond Plus/Metafil C (AQ), Fluoro Bond Shake One/Beautifil (FB), G-Bond/Solare (GB), One-Up Bond F Plus/Palfique Estelite (OF), Xeno IICF Bond/Xeno CF (XE). Bovine mandibular incisors were mounted in self-curing resin and wet ground with #600 SiC to expose labial dentin. The adhesives were applied according to each manufacturer's instructions, and resin pastes were condensed into a mold (ø4x2 mm) immediately, and 1, 2, 5 and 10 minutes after light irradiation of the adhesives. Ten samples per test group were stored in 37 degrees C water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVA followed by Tukey's HSD test (alpha = 0.05) was done. SEM observations of the dentin surface after the tests were also conducted. Dentin bond strength ranged from 9.5 +/- 2.2 to 14.0 +/- 2.4 MPa for AP, 7.3 +/- 2.2 to 12.2 +/- 3.1 MPa for AQ, 10.0 +/- 3.5 to 16.3 +/- 2.4 MPa for FB, 11.4 +/- 1.5 to 16.3 +/- 1.2 MPa for GB, 14.2 +/- 3.4 to 15.1 +/- 3.0 MPa for OF and 11.5 +/- 2.4 to 15.9 +/- 2.2 MPa for XE. Except for OF, no significant differences were found among the 2 to 10 minute delayed placement groups for the systems used. Significant lower bond strengths were obtained for the immediate placement groups except for OF. From SEM observations, cohesive failure of the dentin surface was more pronounced with the longer delay in placement. The data suggest that delayed composite placement over the cured adhesives are suggested for optimum dentin bond strength of single-application self-etch adhesive systems.

Purpose: To determine the influence of interchanging self-etching primers and bonding agents on dentin bond strengths., Methods: Four commercially available self-etching primer dentin bond systems, Clearfil SE Bond (CB), Imperva Fluoro Bond (FB), Mac Bond II (MB), and Unifil Bond (UB) were used. Bovine mandibular incisors were mounted in self-curing resin and the facial dentin surfaces were ground wet on 600-grit SiC paper. The self-etching primers were applied, and four different types of bonding agents were applied on the primed dentin surfaces and cured. The resin-based composites were condensed into the mold (ø4x2 mm) on the dentin surface and light cured. Ten specimens per test group were stored in 37 degrees C water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute. Two-way ANOVA followed by Tukey's multiple comparison tests were done. The temperature change of the bonding agents mixed with the primers was monitored during the exothermic polymerization reaction according to the method of ISO standard #4049. The peak temperature and the time required to reach peak temperature were recorded., Results: When different primers were tested with each bonding agent, only the combination of FB with CBP showed statistically lower bond strengths than the other combinations. When different bonding agents were tested with each primer, CB exhibited the highest bond strengths. The only other statistically significant difference was again the combination of FB and CB. Peak temperature decreased and the time required to reach peak temperature increased with the primer/bonding agent combinations compared to the controls. No exotherm was seen for the combination of FB and CBP.

Statement of Problem: Little is known about how various polymerization combinations of dual-polymerized adhesives and resin core foundation pastes affect dentin bond strength., Purpose: This study examined the influence of different polymerization modes of dual-polymerized resin direct core foundation systems on dentin bond strength using bovine dentin., Material and Methods: Two commercially available dual-polymerized resin direct core foundation systems, Clearfil DC Core and UniFil Core, were studied. Bovine mandibular incisors were mounted in autopolymerizing resin and the facial dentin surfaces were ground wet on 600-grit SiC paper. Dentin surfaces were treated according to manufacturer's recommendations, and dual-polymerized adhesives were applied and dual-polymerized (control) or only chemically polymerized. The core foundation resins were condensed into the mold (4 x 2-mm) and were also either dual-polymerized or only chemically polymerized. Eighty specimens (n=10) were stored in 37 degrees C water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/min in a universal testing machine. Fourier transformation infrared spectroscopy was used to measure the degree of conversion of dual-polymerized resin core foundation pastes with both modes of polymerization. One- and 2-way ANOVA, Tukey HSD tests, and Student t -tests were performed (alpha=.05)., Results: The highest mean bond strengths (+/-SD) were obtained when the adhesives and resin pastes were dual-polymerized for both core foundation systems (14.6 +/- 2.1 MPa for Clearfil DC Core, 15.6 +/- 2.2 MPa for UniFil Core). Chemical polymerization of dual-polymerized adhesives and resin pastes resulted in significantly lower bond strength (2.8 +/- 0.6 MPa for Clearfil DC Core, 8.1 +/- 2.2 MPa for UniFil Core) ( P <.001). The degree of conversion for the resin pastes decreased significantly ( P <.05) when only chemical polymerization was employed, from 81.5% to 76.1% for Clearfil DC Core and 86.7% to 81.2% for UniFil Core., Conclusion: The data suggests that the dentin bond strengths of the dual-polymerized resin direct core foundation systems are highest when both adhesive and resin core paste are dual polymerized.

Resin composites are considered susceptible to environmental conditions that might affect bond strength. This study investigated the influence of relative humidity and temperature on the dentin bond strength of newly developed one-application adhesive systems. Bonding systems employed in this study were five commercial one-application adhesive systems. Labial surfaces of bovine incisors were ground wet on 600-grit SiC paper. The teeth were transferred to a controlled temperature and humidity chamber and the specimens were prepared in six different environmental conditions, A) 25 +/- 0.5 degrees C, 50 +/- 5% RH, B) 25 +/- 0.5 degrees C, 80 +/- 5% RH, C) 25 +/- 0.5 degrees C, 95 +/- 5% RH, D) 37 +/- 0.5 degrees C, 50 +/- 5% RH, E) 37 +/- 0.5 degrees C, 80 +/- 5% RH, F) 37 +/- 0.5 degrees C, 95 +/- 5% RH. The dentin surfaces were treated according to each manufacturer's instructions. Resin composites of each bonding system were condensed into a mold and light irradiated. After storage in 37 degrees C water for 24 hours, 10 specimens per group were tested in a shear mode in a testing machine at a crosshead speed of 1.0 mm/minute. Statistical analysis was carried out with one-way ANOVA followed by Duncan's multiple range tests at a p-value of 0.05. The dentin bond strengths of one-application adhesive systems decreased with increasing RH. These data suggest that the relative high humidity in the oral environment needs consideration in developing clinical procedures for management of these one-application adhesive systems.

This study determined the influence of interchanging adhesive resins and self-etching primers on the mechanical properties of adhesive resins. Four commercially available two-step self-etching primer systems were used. To measure microtensile strength, 0.5-mm thick dumbbell-shaped slabs of each combination of adhesive resin and self-etching primer were prepared. After 24 hours storage in 37 degrees C distilled water, these specimens were subjected to microtensile testing at a crosshead speed of 1.0 mm/minute. Fourier transformation infrared spectroscopy was used to determine the degree of conversion. The percentage of residual double bonds, including pendant and monomeric double bonds, was calculated by comparing the obtained ratio against uncured adhesive resin. The degree of conversion of the adhesive resins was obtained by subtracting the %C=C from 100%. Two-way ANOVAs, followed by Tukey tests, were done. The microtensile strengths and degree of conversion varied with different combinations of self-etching primer and adhesive resin. Numerically, the highest microtensile strengths were obtained when the primer/adhesive resin combinations from the same manufacturer were used. When the different combinations of self-etching primers and adhesive resins were mixed, the microtensile strength and degree of conversion of the adhesive resins tended to decrease for some combinations. Within the limitations of this study, which was far removed from clinical situations, the role of the self-etching primers on the mechanical properties of adhesive resins should be considered to create an authentic resin-dentin interface.

Purpose: Though reduction in bond strength after tooth whitening has been reported, little is known about it's effect on enamel bond strength of two-step bonding systems that exclude phosphoric acid etching prior to bonding agent application. The purpose of this study was to determine the effect of whitening procedure using an in-office whitening agent on enamel bond strength of self-etching primer systems., Methods: Three self-etching primer systems, Imperva Fluoro Bond, Mac Bond II, Clearfil SE Bond, and a one-bottle adhesive system Single Bond as a control material, were used. Bovine mandibular incisors were mounted in self-curing resin and the facial enamel or dentin surfaces were ground wet on 600-grit SiC paper. An in-office whitening agent, Hi-Lite was applied on the tooth surface according to the manufacturer's instruction. Bonding procedures were done soon after rinsing off the whitening agent or after 24 hours storage in distilled water. Specimens without whitening procedure were prepared as controls. Fifteen specimens per test group were stored in 37 degrees C distilled water for 24 hours, then shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVA followed by Duncan multiple range test were used for statistical analysis of the results., Results: For the specimens made soon after rinsing off the whitening agent, a significant decrease in enamel bond strength was observed for all the bonding systems used. For the specimens made after 24 hours storage in water, a small decrease in enamel bond strength was observed and no significant differences were found compared to those of controls (without whitening). From the results of this study, enamel bond strengths of the self-etching primer systems might be affected to a lesser degree after rinsing with water followed by 24 hours storage in water.

Purpose: The purpose of this study was twofold: 1. To compare two different research models for simulating a traumatic anterior tooth fracture: the blunt trauma method (standard method) and an AL2O3 sectioning method (experimental method). 2. To compare the bond strength of tooth fragments bonded with resin modified glass ionomer vs. a light cured composite resin., Methods: Two hundred bovine incisors were used in the study and kept in plain tap water throughout. The study consisted of five basic steps: 1. Fracture of the teeth by either blunt trauma (chisel and hammer) or AL2O3 sectioning disc. 2. Luting of the fractured fragments back to the teeth using either a composite resin or resin modified glass ionomer. 3. Thermocycling of the repaired teeth. 4. Dislodging the teeth to determine the strength of repair. 5. Determination of fracture type., Results: One-way ANOVA revealed a statistically significant difference in the forces required to fracture the resin modified glass ionomer and composite resin regardless of whether the teeth were originally fractured with the blunt force method (p=0.030) or the disc sectioning method (p=.001). One-way ANOVA also revealed a statistically significant difference between the forces required for fracture by blunt trauma and the disc fracture techniques with the resin modified glass ionomer group (p=0.000345). However, there was no significant difference when the two techniques were compared for the composite resin (p= 0.2941)., Conclusions: 1. The resin modified glass ionomer was significantly stronger than the composite resin when both the blunt trauma and the disc fracture techniques were employed. 2. The study's results do not support substituting the ease of the AL2O3 disc for the more time-consuming blunt trauma method.

The difficulty related to achieving a balance between wet and dry dentin makes the dentin bonding technique extremely sensitive. This study evaluated the effect of rewetting dried dentin with two commercial desensitizing agents (Protect and HurriSeal) on the dentin shear bond strength of three total-etch dentin bonding agents (Syntac Single-Component, OptiBond Solo Plus and Prime & Bond NT) and compared both to applying these same bonding agents to moist dentin and dry dentin. Each bonding agent was paired with an appropriate resin composite from the same manufacturer (Table 1). Recently extracted, formalin-treated caries-free human molars were used. The occlusal surface of each tooth was ground to create a flat dentin surface. Then, each tooth was mounted in acrylic. Twelve groups (n = 15) were prepared: 1) Syntac Single-Component with Heliomolar resin composite (SSC/H) to moist dentin; 2) SSC/H to dry dentin; 3) SSC/H to dried dentin rewet with Protect; 4) SSC/H to dried dentin rewet with HurriSeal; 5) OptiBond Solo Plus with Point 4 resin composite (OBS+/P4) to moist dentin; 6) OBS+/P4 to dry dentin; 7) OBS+/P4 to dried dentin rewet with Protect; 8) OBS+/P4 to dried dentin rewet with HurriSeal; 9) Prime & Bond NT with TPH Spectrum resin composite (PBNT/TPH) to moist dentin; 10) PBNT/TPH to dry dentin; 11) PBNT/THP to dried dentin rewet with Protect and 12) PBNT/TPH to dried dentin rewet with HurriSeal. Groups 1, 5 and 9 were placed according to manufacturers' instructions (moist dentin) as control groups. All the other groups received a 15-second air blast after etching and prior to applying the one bottle adhesive or desensitizer and one bottle adhesive. Resin composite cylinders [4 mm in diameter and 2 mm in height] were then placed. The specimens were stored in distilled water at 37 degrees C for 24 hours prior to thermocycling 2,500 times (at 8 degrees C and 48 degrees C). Shear bond strengths (SBSs) were measured one week after fabrication by using a circular knife-edge and crosshead speeds of 0.5 mm/minute. Failure modes of debonded specimens were determined under a stereomicroscope (30x). Failed specimens with the low and high shear bond strengths in each group were evaluated under a low vacuum Scanning Electron Microscope (SEM-LV). One-way ANOVA and Tukey's tests were used to compare the different conditions for each bonding system. In the Syntac Single-Component bonding agent groups, there was no significant difference in shear bond strength between the control (15.73 MPa), dry (18.11 MPa) and HurriSeal (16.18 MPa) specimens. Protect specimens showed significantly lower shear bond strength (6.39 MPa). In the OptiBond Solo Plus bonding agent groups, there was no significant difference between the control (20.79 MPa) and the HurriSeal (21.29 MPa) groups, and both groups had significantly greater bonds than the dry (14.13MPa) and Protect (9.57 MPa) groups. In the Prime & Bond NT bonding agent groups, the shear bond strength of the HurriSeal group (20.73 MPa) was significantly higher than the other groups: control (8.05 MPa), dry (5.73 MPa) and Protect (5.45 MPa).

Adhesion of resin composites into enamel is currently believed to rely on infiltration of bonding resin into the porous zone, establishing micromechanical retention to etched enamel. This study investigated the change in chemical composition of the enamel/resin interface using a laser Raman microscopic system (System-2000, Renishaw). Two-step bonding systems, Mac Bond II (Tokuyama Corp), Clearfil Mega Bond and Single Bond (3M/ESPE) were employed. Resin composites were bonded to bovine enamel with bonding systems and sectioned through the bonded interface. The sectioned surfaces were then polished with diamond pastes down to 1.0 microm particle size. Raman spectra were successively recorded along a line perpendicular to the enamel/ resin interface. The sample stage was moved in 0.2 microm increments on a computer-controlled X-Y precision table. Additional spectra from samples of enamel and cured bonding resins were recorded for reference. The relative amounts of the hydroxyapatite (960cm(-1), P-O), bonding agent (640cm(-1), aromatic ring) and alkyl group (1450cm(-1), C-H) in the enamel/resin bonding area were calculated. From Raman spectroscopy, a gradual decrease in hydroxyapatite was observed, and it was estimated to extend 2.2-2.6 microm for Mac Bond II, 1.2-1.6 pm for Clearfil Mega Bond and 5.2-5.6 microm for Single Bond. Furthermore, the enamel/resin interface represents a gradual transition of bonding agent from the resin to tooth side. Evidence of poor saturation of adhesive resin in etched enamel with Single Bond was detected. From the results of this study, non-uniform resin infiltration into etched enamel was detected and the degree of resin infiltration was found to be different among the bonding systems used.

Objectives: Adhesion of resin-bonding agents to dentin is currently believed to result from impregnation of adhesive resin into superficially demineralized dentin. The purpose of this study was to investigate the chemical composition of the resin-impregnated dentin (hybrid) layer using a micro-Raman spectroscopy., Methods: Resin composites were bonded to bovine dentin with the two-step bonding systems, and specimens were sectioned parallel to dentinal tubules. These surfaces were then polished down to 1 microm diamond pastes. Raman spectra were successively recorded along a line perpendicular to the dentin-adhesive interface by steps of 0.2 microm on a computer controlled X-Y stage. The relative amounts of hydroxyapatite (960 cm(-1), P-O), adhesive resin (640 cm(-1), aromatic ring), and organic substrate (1450 cm(-1), C-H) in the dentin-adhesive bonding area were calculated., Results: From the Raman spectroscopy results, the hybrid layer represents a gradual transition in the relative amount of adhesive from the resin side to dentin side. Evidence of poor saturation of the adhesive resin in the demineralized dentin with the one-bottle adhesive system was detected., Significance: From the results of this study, inhomogeneity of the hybrid layer composition was detected, and the degree of resin impregnation was found to be different between the bonding systems tested.

Purpose: To investigate the bonding ability to enamel and dentin of new single application bonding systems (Reactmer and One-Up Bond) and compare these with a commercial compomer (Clicker/F2000), and 2-step resin-based composite bonding systems (Fluoro Bond/Lite-Fil II A and Single Bond/Z100)., Materials and Methods: Labial surfaces of extracted bovine teeth were ground on wet 600-grit SiC paper to expose a flattened area of enamel or dentin and then washed and dried with oil-free compressed air. These surfaces were treated according to each adhesive system's instructions and the restorative materials were condensed into a Teflon mold (2 mm height, 4 mm internal diameter) and then irradiated. The finished specimens were stored in 37 degrees C distilled water for 24 hours from the start of light exposure to the material. Then these specimens were tested in a shear mode at a crosshead speed of 1.0 mm/minute. The mean and standard deviation were subjected to an ANOVA followed by the Duncan test (P< 0.05)., Results: The bond strengths of the single application bonding systems were 12.3 to approximately 14.5 MPa for enamel, and 13.7 to approximately 13.8 MPa for dentin. These values were comparable to those of the compomer (12.6 MPa for enamel, and 13.1 MPa for dentin), but lower than those of the two-step resin composite bonding systems (16.8 to approximately 21.7 MPa for enamel and 18.1 to approximately 18.4 MPa for dentin).

The development of one-bottle dentin adhesive systems resulted in much optimism about providing simplified predictable esthetic dentistry. However, laboratory testing of these systems continues to provide significant variations between facilities. A potential effect of the number of applications was noted in this author's laboratory. This study evaluated the effect of doubling the manufacturer's recommended number of applications on shear bond strength to dentin. Ninety human molars were divided into groups of 15. The occlusal surfaces were finished to 600 grit SiC to provide a flat dentin bonding surface. Prime & Bond NT-Dyract, Optibond Solo-Elan and One Step-Dyract were evaluated. Each material was tested using: (1) the recommended number of adhesive applications and (2) twice the number of applications recommended. All adhesive applications were accomplished before light curing the adhesive. The specimens were thermocycled after one week of storage and tested in shear after two weeks. Specimens were also fabricated after adding Rhodamine D to the adhesive to allow for visualization using confocal microscopy. These teeth were sectioned and viewed 24 hours after fabrication. A t-test was used to compare differences within product groups. The results showed a significant effect (p < 0.001) when a double application of Prime & Bond NT was used. No difference was seen with Optibond Solo or One Step. All specimens appeared to have a uniform, glossy appearance of adhesive during fabrication. Therefore, the appearance of the adhesive after application may not be a reliable predictor of acceptable bonding. Confocal microscopy showed that single application Prime & Bond NT specimens did not exhibit a uniform thickness of adhesive across the entire interface. Tubule penetration and hybridization was apparent for all specimens.

Dentin bonding agents have been shown to enhance retention of amalgam restorations by mechanical means. Little research is available on which mode of curing may optimize amalgam bonding. This in vitro study compared the bond strengths exhibited by three variations of a bonding agent, each using a different curing mode, with two earlier versions of amalgam resin liners and cavity varnish. The six test groups of lining agents for amalgam restorations included [C] chemical-cured, [L] light-cured and [D] dual-cured versions of one filled adhesive resin (Clearfil Liner Bond 2V), [LF] Light-cured, Filled resin (Clearfil Liner Bond 2, Kuraray Co.); [LCF] Light- and Chemical-cured, Filled resin Clearfil Liner Bond + Protect Liner, Kuraray Co) and [V] Varnish (Copalite, Cooley & Cooley, Ltd). For each group, 20 Class V cavity preparations were cut in human molars. The preparations were 2.5 mm deep and 3 mm wide at the pulpal floor, with a slightly divergent taper. After treating the preparation with the bonding agent, a 3/4 inch, 18 gauge flat-headed wire nail was seated in the cavity with its head at the pulpal floor of the preparation, and Tytin amalgam (Kerr Corp, Romulus, MI) was condensed into the preparation around the nail. All restorations were stored for 24 hours in distilled water at 37 degrees C, then subjected to 2500 thermal cycles (8 degrees C to 58 degrees C). After one week the samples were tested to failure in tension using an Instron Universal Testing Machine (crosshead speed = 2 mm/min) and peak load (kg) was recorded. Significant differences in retention were found using ANOVA and the Games & Howell post hoc test (p = 0.05). The mean loads at failure (+/- SD) were C 13.1 (+/- 2.4), L 21.8 (+/- 6.1), D 26.8 (+/- 7.4), LCF 23.8 (+/- 7.4), LF 21.4 (+/- 3.3) and V 2.0 (+/- 1.8). All dentin-bonding agents exhibited significantly greater retention than the varnish. While the bond strengths of the dual cured (D) and the light-cured (L) liners were not significantly different from one another, both were significantly higher than the chemically-cured (C) resin liner in terms of retention.

Purpose: To compare the microleakage and bond strength exhibited by two light-cured, filled dentin bonding agents, a resin cement, and cavity varnish., Materials and Methods: The four test groups of lining agents for amalgam restorations included (LF) Light-cured, Filled resin (Clearfil Liner Bond 2); (LCF) light- and chemical-cured, Filled resin (Clearfil Liner Bond + Protect Liner); (RC) Resin Cement (Panavia 21); and (V) Varnish (Copalite). For each group, 20 Class V cavity preparations were cut in human extracted molars. Tytin amalgam was condensed into the preparation. After storage for at least 24 hrs in distilled water at 37 degrees C, all restorations were subjected to 2500 thermal cycles (8 degrees C to 48 degrees C). After 1 wk, specimens were tested. For the leakage tests, teeth were immersed in 45Ca, sectioned, and radiographs of sections were evaluated and then evaluated by Ridit analysis. Retention samples were tested to failure in tension using an Instron machine and peak load (kg) was recorded., Results: Compared to varnish, the two dentin bonding agents (LF and LCF) significantly decreased microleakage at the cementum margin but not at the enamel margin. The two dentin bonding agents also exhibited significantly greater retentive strength than either the resin cement or the varnish.

Purpose: To examine the influence of operator variability on adhesion to dentin of recently developed two-step bonding systems., Materials and Methods: A self-etching primer system, Fluoro Bond/Lite-Fil II A (FB) and a one-bottle adhesive system, Single Bond/Z100 (SB) were employed. Three groups, each consisting of 15 operators, were selected from the dentists at the university (Group 1), undergraduate students (Group 2), and general practitioners (Group 3). Labial surfaces of extracted bovine teeth were ground on wet 600-grit SiC paper and then washed and dried with oil-free compressed air. These surfaces were treated according to each adhesive system's instructions and the restorative resins were condensed into a Teflon mold (2 mm height, 4 mm internal diameter) and then light-cured. The finished specimens were stored in 37 degrees C distilled water for 1 hr. These specimens were tested in a shear mode at a cross-head speed of 1.0 mm/min. The mean and standard deviation were subjected to two-way ANOVA (P < 0.05)., Results: Significant differences in bond strength of the two adhesives were found within each operator group. A wider variation in bond strength was seen for SB compared to FB for the three different groups. Mean bond strengths for the faculty group were statistically greater than those of the other two groups, which did not differ significantly. Even though the specimen preparation was done under in vitro conditions, the large coefficients of variation indicate it may be difficult to create suitable surface conditions for optimal bonding.

The purpose of this study was to investigate the rate of development of dentin bond strengths of resin-modified glass-ionomer cements (RMGIC) with use of dentin primers. The prepared dentin surface was treated according to each manufacturer's instruction or the dentin primer. Cements were condensed into a vinyl mold and light activated. The shear bond strengths were measured at a crosshead speed of 1.0 mm/min after 1, 5, 10, 30, 60 min, 2, 5, and 24 h storage in water at 37 degrees C. Presence of a significant difference between the mean bond strength at 1 min and each of the other test times was analyzed. The first time at which there was a significant increase in bond strength was defined as the "initial increasing time". As compared with the manufacturer's suggested dentin treatments, the bond strengths increased significantly when the dentin primers were used. The initial increasing times when the specimens were made following each manufacturer's instructions were 10 approximately 60 min. When dentin primer was used, the initial increasing time shortened to 5 approximately 10 min. It was concluded that the use of dentin primers for RMGIC restorations resulted in reduction of the initial increasing time.

Objectives: In clinical situations, a dentine primer is usually applied to enamel, in addition to dentine. This study was carried out to determine the influence of the air drying time of self-etching primers on their bond strength to enamel., Methods: Three self-etching primer systems, Fluoro Bond (FB, Shofu Inc.), Liner Bond II (LB, Kuraray Co.) and Mac Bond 2 (MB, Tokuyama Co.) were employed. Bovine mandibular incisors were mounted in self-curing resin and the enamel surfaces were wet ground with number 600 SiC paper. Following primer application, the enamel surface was dried with compressed air for 0, 2, 5, 10, 20, and 30 s from 10 cm above the enamel surface using a three-way syringe. Adhesives were applied and composites were condensed into a Teflon mold (4 x 2 mm) placed on the enamel and light activated. Ten samples per test group were stored in 37 degrees C water for 24 h, then shear tested at a crosshead speed of 1.0 mm min-1. One-way ANOVAs followed by Duncan tests (p < 0.05) were done., Results: The enamel bond strengths varied with the different air drying times and ranged from 8.2 +/- 3.2-17.4 +/- 3.0 MPa for LB, 10.9 +/- 2.8-16.3 +/- 3.3 MPa for FB, and 17.5 +/- 2.5-19.4 +/- 2.2 MPa for MB. For LB and FB, there appeared to be a minimum drying time of 10 s. LB was the most affected by drying time, while MB did not change., Conclusions: The data suggests that the enamel bond strengths of these bonding systems can be influenced by the drying time of the primer applied prior to bond agent application and the tendency was different among the systems studied.

Purpose: To investigate the influence of thermal cycling on bond strength to dentin of 2-step bonding systems., Materials and Methods: The systems used were self-etching primer systems; Fluoro Bond (FB), Liner Bond II (LB), and Mac Bond II (MB); and self-priming adhesive systems; One-Step (OS), OptiBond Solo (OB), Prime & Bond 2.0 (PB), and Single Bond (SB). Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were wet ground with #600 SiC paper. Enamel and dentin surfaces were treated following each manufacturers' instructions. Adhesives were applied and composites were condensed into a Teflon mold (4x2 mm) placed on the dentin surface and light activated. Bonded specimens were divided into four groups; (a) stored in 37 degrees C water for 24 hours, (b) stored in 37 degrees C water for 24 hours followed by subjecting to thermal cycling between 5 degrees C and 60 degrees C for 3,000 times, (c) 10,000 times, and (d) 30,000 times. Twelve samples per test group were shear tested at a crosshead speed of 1.0 mm/minute. One-way ANOVAs followed by Duncan's multiple range test (P < 0.05) were performed., Results: For FB, LB, and MB, a small decrease in bond strength was observed and no significant differences were observed among the thermal cycling groups. For OS, OB, PB, and SB, a significant decrease in bond strength was observed for the 30,000 thermal cycling groups. The changes in bond strength after TC were different between the bonding systems.

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).

Previous studies on amalgam bonded restorations indicated that amalgam bonding agents increased the bond strength of amalgam to tooth structure. This in vitro study was designed to compare how the mode of curing and the presence of filler in the resin would affect the bond strength of amalgam. The five test groups of lining agents for amalgam restorations included Chemical-cured, Unfilled resin (CU-Clearfil New Bond); Light-cured, Unfilled resin with a delayed chemical-cure property (LU*-Clearfil Photo Bond); Light-cured, Filled resin with a delayed chemical-cure property (LF*-Clearfil Photo Bond + Protect Liner); Dual-cured, Unfilled resin (DU-All-Bond 2); and Varnish (V-Copalite). For each group, 20 class 5 cavity preparations were cut on the facial, lingual, or proximal surfaces of human molars, which were embedded in acrylic resin. The preparations were 2.5 mm deep and 3 mm wide at the pulpal floor with a slightly divergent taper. After treating the preparation with the bonding agent, a 3/4-inch, 18-gauge flat-headed wire nail was placed into the cavity with the head at the pulpal floor of the preparation, and Tytin amalgam was then condensed into the preparation around the nail. The restorations were stored for 24 hours in distilled water at 37 degrees C and then subjected to 2500 thermal cycles (8 degrees C to 48 degrees C). After 1 week, specimens were tested to failure in tension using an Instron Universal Testing Machine (crosshead speed = 2 mm/min) and peak load (kg) was recorded. The mean loads at failure (+/- SD) were LF* 26.4 (+/- 7.0), DU 23.9 (+/- 6.4), LU* 16.0 (+/- 3.1), CU 14.3 (+/- 8.0), and V 9.5 (+/- 5.6). Significant differences were found using a one-way ANOVA and the Games and Howell post hoc test at a significance level of alpha = 0.05. The LF* and DU groups were not significantly different from each other, but they were significantly higher in peak load than all other groups. LU* was significantly higher than the varnish (V) but not significantly higher than CU. CU was not significantly higher than the varnish (V). The adhesives forming a thicker resin interface (the light-cured resin with filled resin liner and the dual-cured unfilled resin) demonstrated significantly greater retention than the light-cured unfilled resin, chemical-cured unfilled resin, and the varnish control.

The purpose of this study was to compare the degree and pathway of microleakage in bonded amalgam restorations utilizing fluorescent dyes with scanning laser confocal microscopy and 45Ca radioisotope with autoradiographs. Mesial slot preparations with enamel cervical margins and distal preparations with dentin margins were prepared in extracted human molars. Four liners, Copalite (control) All-Bond 2/Resinomer, Amalcoden, and Panavia 21, were used. Teeth were restored with Dispersalloy or Tytin. After thermocycling, 7 days' storage, and staining, the degree of microleakage was measured on an ordinal scale. Dental adhesive liners minimized microleakage; the ranking was, from most to least effective, All-Bond 2, Panavia 21, and Amalcoden. The control exhibited the greatest microleakage. Microleakage occurred most frequently at the liner-tooth interface. No significant difference was observed between amalgams. The high correlation between the results of the fluorescent and radioisotope studies indicated that these two microleakage tests can be directly compared.

This study was carried out to determine the influence of dentin primer application methods on bond strength to human dentin. Two dentin bonding restorative systems, Imperva Bond/Lite-Fil II A (Shofu) and Scotchbond Multi-Purpose/Z-100 (3M) were employed. Human molars were mounted in self-cured resin and the buccal surfaces were prepared with #600-grit SiC paper. These surfaces were then conditioned according to each manufacturer's instructions. Two experiments were designed: (1) effect of the primer application procedures (inactive and active application), and (2) effect of the air drying time (0, 1, 5, 10, 20, and 30 seconds). The adhesives were applied and resin composites were bonded to the teeth. Ten samples per test group were stored in 37 degrees C deionized water for 24 hours, and shear tested with a circular knife edge at a crosshead speed of 1.0 mm/minute. A one-way ANOVA followed by the Newman-Keuls multiple comparison at P < 0.05 was done. For both restorative systems, the bond strengths for active application were higher than those for inactive application, but there was no significant difference between the two mean values. According to the air drying time, there appeared to be an optimal range of drying times, longer for Imperva Bond (10-30 seconds) than for Scotchbond MP (1-5 seconds). The data suggest that the bond strengths of employed dentin bonding systems were greatly influenced by the methods of the dentin primer application.

This study evaluated the effect of bonded amalgam on the fracture strength of teeth using five adhesive systems: Panavia 21, Amalgambond Plus, Imperva Dual Bond, All-Bond 2 Primer/Bonding Resin, and All-Bond 2 Primer/Liner F. Intact teeth and amalgam lined with Copalite were used as control groups. Large MOD preparations were made in 20 extracted maxillary premolars for each group. The teeth were restored with Tytin. All groups were stored in water at 37 degrees C for 15 days and thermocycled 2500 times, over 8-48 degrees C. The specimens were preloaded five times in compression to 10 kg using a 5 mm-in-diameter, cylindrical steel indenter that contacted the teeth only on the cuspal inclines. Then the teeth were loaded to failure at 5.0 mm/min. The failure mode was recorded (amalgam failure, cusp fracture, or failure at the tooth/amalgam interface). The mean fracture strengths were analyzed using ANOVA and Newman-Keuls multiple comparisons. The Imperva Dual Bond group showed the highest mean forces followed by All-Bond 2 Primer/Bonding Resin. The All-Bond 2 Primer/Liner F and Amalgambond Plus groups demonstrated lower means and were not significantly different from the Copalite group. The Panavia 21 group was in between these two groups and was not statistically different from either group. The mean strength of intact teeth was the highest, but its very large coefficient of variation (60%) prevented effective use of these data for statistical comparison. Analysis of the mode of fracture showed that Panavia 21, All-Bond 2 Primer/Bonding Resin, and Amalgambond Plus failed cohesively in the amalgam in 35%, 25%, and 15% of the specimens respectively. This fracture type is a good indication of effective bonding between tooth and amalgam. The most common type of fracture for all the restored groups was the one that occurred at the tooth/restoration interface. This would suggest that current bonding procedures could be improved.

Objective: The purpose of this study was to examine the influence of light irradiation of dentine primers that contain camphoroquinone (CQ) on the shear bond strength to dentine and their contact angle., Method: Three dentine bonding systems which contain CQ, Imperva Bond, OptiBond and XR-Bond; and Light Bond, which does not contain CQ, were employed. Labial surfaces of freshly extracted lower bovine incisors were ground with no. 600 grit SiC paper. Dentine primers were applied to the dentine surfaces in two groups, irradiated and non-irradiated. A shear bond strength test was performed and the direct contact angle was measured., Results: Statistical analysis (Newman-Keuls multiple comparison P < 0.05) of the data indicated that light irradiation of the dentine primer for systems containing CQ resulted in increased bond strength and decreased contact angle., Conclusion: This study indicates that for these dentine bonding systems containing CQ in their primers, light irradiation of the dentine primer is effective in improving wettability and increasing the bond strength to dentine.

Purpose: To investigate the influence of light intensity on dentin bond strength of five dentin bonding systems., Material and Methods: The light intensity used to polymerize specimens was controlled at the levels of 100, 200, 400, 600, 800, and 1000 W/m2 (470 +/- 40 nm). Labial surfaces of freshly extracted lower bovine incisors were ground with #600 grit SiC paper to expose dentin. After primer application, bonding agents were applied and bonded with resin composites. A shear bond strength test was performed and the data were analyzed by a one-way ANOVA followed by Newman-Keuls multiple comparison (P<0.05)., Results: Statistical analysis of the data indicated that light intensity affected the bond strength to dentin. The mean bond strength of all bonding systems decreased with lower light intensity. The tendency of decreasing bond strength was different among the test materials and each test material had a threshold light intensity that resulted in statistically the same bond strength obtained using a light intensity of 1000 W/m2.

The purpose of this study was to compare the enamel shear bond strengths achieved with four acid conditioners employed by current enamel/dentin bonding systems (maleic acid, citric acid, nitric acid, oxalic acid) with a 37% phosphoric acid etching technique. The study also compared enamel shear bond strengths between the manufacturers' enamel/dentin conditioner used with an unfilled enamel bonding resin. The facial surfaces of 135 bovine incisors were ground flat and divided into nine test groups of n=15. Conditioning and bonding procedures were carried out following manufacturers' instructions. The phosphoric acid groups were etched for 15 seconds, rinsed for 30 seconds, and dried for 20 seconds with compressed air. All bonding was accomplished at a constant temperature of 21 degrees C and a relative humidity of 60%. A single composite restorative resin (Z-100) was used with all specimens to eliminate variables between composite materials. All specimens were thermocycled 2500 times (5 to 45 degrees C) and had a total storage time of 21 days prior to shear testing on an Instron at a crosshead speed of 1.0 mm/minute. Shear strengths were calculated by dividing load at failure by specimen area. A light microscope was used to determine failure mode. The data were subjected to Bartlett's test for homogeneity of variance and were found not to be homogeneous. The Welch Test was applied and indicated that the treatments used had influence on bond strength at P<0.05. There was no significant difference in bond strength values between traditional phosphoric acid/enamel bonding resin and Mirage Bond Dentin and Enamel Adhesive, Clearfil Liner Bond System, and Scotchbond Multi-Purpose Dental Adhesive System.

The optimal conditions for opaquing techniques during porcelain application have not been confirmed. In this study the metal-ceramic bond strength was measured among one porcelain and three dental alloys, namely a gold-platinum-palladium alloy, a silver-free gold-palladium alloy, and a base metal alloy, with two opaquing techniques (a single masking layer versus a thin overfired layer followed by a second masking layer). In addition, the opaque porcelain was fired over an oxidized and nonoxidized alloy surface for the silver-free gold-palladium alloy. No significant differences in bond strength were recorded between the two opaquing techniques with the gold-platinum-palladium and base metal alloys. There was no substantial differences between the two opaquing techniques when opaque was applied over an oxidized gold-palladium alloy surface and bond strengths were substantially greater over an oxidized surface. However, when the opaque was applied to a nonoxidized gold-palladium surface the two-layer technique created a significantly greater bond strength.

Objectives: The purpose of this study was to investigate the influence of adding filler particles to a bonding agent on dentin bond strength and of the temperature change during curing in order to determine the optimum filler level for an experimental bonding agent., Methods: Experimental light-cured bonding agents with microfiller (average size: 0.05 micrometers) content of 0, 10, 20, 30, 40, 50, 60, and 70 wt% were used with the Imperva Bond / Lite-Fil II A (Shofu) restorative material. Bovine incisors were mounted in self-cured resin, and the facial surfaces were prepared with 600-grit SiC paper. After dentin surface pretreatment with dentin primer, experimental bonding agents were applied to the dentin surface and bonded with resin composite. Ten samples per test group were stored in 37 degrees C water for 24 h, then shear tested at 1.0 mm/min. The temperature change of the bonding agent was monitored during the exthothermic polymerization reaction according to the method of ISO standard #4049. The peak temperature and the time required to reach peak temperature were recorded., Results: Bond strength to dentin and the temperature change were greatly affected by the filler level. Maximum dentin bond strength (14.3 +/- 2.3 MPa) was obtained with a filler level of 10 wt% and decreased with filler level higher than 30 wt% (10.4 +/- 1.7 MPa - 5.3 +/- 2.6 MPa). Peak temperature decreased and the time required to reach peak temperature increased with the higher filler levels. There were strong correlations between the bond strength and temperature change of experimental bonding agents., Significance: The initial setting behavior of bonding agents containing filler particles may be one of the important factors influencing dentin bond strength. When bonding agents with filler particles are used, it is important to determine if optimum filler levels exist in order to optimize the dentin bond strength.

The shear bond strength of two light-activated resin composite materials to a preformed heat-polymerized resin material was measured. The substrate was a urethane dimethacrylate material designed for use as a direct bonded pontic. In the first phase of the study, the shear bond strength between the substrate and a urethane-based resin composite and seven surface treatments was evaluated. In the second phase, a Bis-GMA resin composite and three surface treatments were studied. The study showed that a bonding agent was essential for the achievement of an adequate bond strength between the light-activated and heat-polymerized resin. However, there was a significant difference in bond strength depending on the type of light-activated resin composite and bond agent used. A Bis-GMA-based light-activated composite, together with its bond system (22.82 MPa), provided higher bond strength than a urethane-based resin composite and its bonding system (14.45 MPa). There was a direct relationship between cohesive failure and bond strength; as bond strength increased, the number of cohesive failures increased as well.

Objectives: The correlation between shear bond strength and surface roughness was investigated using new surface measurement methods., Methods: Bonding agents and associated resin composites were applied to set amalgam after mechanically roughening its surface. Surface treatments were noe (as set against glass), 80 grit, and 600 grit abrasive paper. Surface roughness (R(a) as measured parallel and perpendicular (+) to the direction of the polishing scratches and true profile length were measured. A knife-edge was applied (rate = 2.54 mm/min) at the bonding agent/amalgam interface of each sample until failure., Results: Coefficients of determination for mean bond strength vs either roughness (R(a), of profile length were significantly higher for measurements in parallel directions than for those measurements in (+) directions. The shear bond strength to set amalgam for a PENTA-containing adhesives system (L.D. Caulk Division) was not significantly different from that of a PENTA-free adhesive (3M Dental Products Division), even though PENTA has been reported to increase bond strength to nonprecious metals., Significance: The shear bond strength of resin composite to amalgam is correlated to surface roughness when it is measured parallel to the polishing scratches. This correlation is significantly lower when surface roughness is measured in the typical manner, perpendicular to the polishing scratches.

A finite element model (FEM) of an orthodontic bracket bonded to enamel with glass ionomer cement was developed. The loading on the model simulated tensile loading conditions associated with the testing of bonding system strength. The primary purpose of this project was to ascertain the effects of load misalignment on the calculated stresses within the cement layer. The results indicate that peak stress values increase as the load deflection angulation increases. If the tensile load is inadvertently applied entirely on one wing of the bracket, the stress components nearly double in magnitude.

Three variables associated with adhesion testing were examined: (1) the test mode, shear and tension; (2) design of the tensile apparatus; and (3) tooth substrate, human and bovine. Findings revealed no significant differences in bond strength by one tensile test and a shear test. However, the shear test produced more true adhesive failures; thus it may be preferable to use a shear test for adhesion testing. Bond strengths with some adhesive systems differed significantly when tested by two different tensile apparatus. Design of the test apparatus appeared to affect values. Bond strength measurements obtained with human and bovine enamel were essentially comparable. Values with dentin varied. There appeared to be a trend for higher bond strength values with bovine than with human dentin.

This in vitro study evaluated the ability of three commercially available adhesive resins to reduce microleakage and provide retention between amalgam restorations and tooth structure. Results indicated that Amalgambond reduced leakage significantly more than Panavia EX, Prisma Universal Bond 2, and Copalite. In addition Amalgambond and Panavia EX exhibited the ability to bond amalgam to tooth structure. These results suggest that Amalgambond has the potential for serving successfully as a cavity liner with amalgam.

Surface pH measurements were made over a 24-hour period for several luting cements and glass-ionomer lining and restorative materials. Of the luting cements, the water-mixed glass-ionomer cement, Ketac-Cem, had the lowest initial pH and the polycarboxylate, Durelon, had the highest. Three glass-ionomer lining materials showed differences in pH that increased over the entire test period. Two of the three visible-light-cured glass-ionomer liners evaluated showed similar pH values, while the third exhibited a considerably lower pH. The lower pH values found with the water-mixed glass-ionomer luting agent suggest that acidity may contribute to the posttreatment sensitivity associated with this material.

The bonding of light-cured composites to tooth tissues is known to be disturbed by polymerization shrinkage, and polymerization shrinkage is affected by the filler content of composites. This in vitro research examined the relationship between the filler content and bond strength to dentine of light-cured composites. Experimental light-cured composite systems with filler contents of 45, 55, 65 and 75 per cent by volume were used in both bond strength to dentine and shrinkage tests. The surfaces selected as substrates were a flat surface and a box-shaped cavity prepared in bovine dentine. The lowest bond strength was obtained with the 45 per cent filler content composite in the box-shaped cavity. Bond strength increased with increasing filler content. Volumetric polymerization shrinkage decreased with increasing filler content. The polymerization shrinkage at 120 s after light curing was 5.24 per cent for the 45 per cent filler content system, 4.77 per cent for the 55 per cent, 2.14 per cent for the 65 per cent and 1.68 per cent for the 75 per cent. The correlation between bond strength and shrinkage was greater for the cavity than it was for the flat surface. This implies that bond strength in the box-shaped cavity may have been affected more by polymerization shrinkage than with the flat surface. The findings lend support to the view that filler content is one of the important factors influencing the physical properties of composites.

The effect of sample age on the shear bond strengths of two dentin bonding agents to human dentin was evaluated by bonding composite resins to human dentin treated with either Imperva-Bond or Prisma Universal Bond 3. One-half of the specimens were tested at 5 minutes, while the remainder were thermocycled and tested at 2 weeks. Results were analyzed using two sample t tests at the 0.05 probability levels. Failures were evaluated using light microscopy and categorized as adhesive, cohesive within resin, cohesive within tooth, or mixed. The bond strengths were significantly higher for Imperva-Bond than for Prisma Universal Bond 3 at both time periods. For both bonding agents, the 2 week bond strengths were significantly higher than the 5 minute bond strengths. The 2 week bond strength of Imperva-Bond approaches that of unfilled resin to etched enamel.

Two Type II glass polyalkenoate (ionomer) cements were evaluated for their repairability by measuring tensile bond strength of new material added to previously placed cement. Variables included time of repair (20 min vs. 24 h) and surface condition prior to repair (smooth and unetched, smooth and etched, rough and unetched, rough and etched). Failures were evaluated using light microscopy and categorized as cohesive, adhesive, or mixed. Scanning electron microscopy was employed to view the cement surfaces following each of the four pretreatments. Surface pretreatment was found to significantly affect both materials when repaired at 20 min (P less than 0.05). The highest bond strength was achieved when bonding to the smooth, unetched surface. Surface pretreatment did not significantly affect bond strength when the cements were repaired at 24 h (P greater than 0.05). Tensile bond strengths were greater for repairs made at 20 min than for those made at 24 h, but the differences were not always statistically significant.

This study evaluated the effects of two adhesive resin liners (Panavia EX and Amalgambond) on the compressive strength and creep rate of a single composition high-copper amalgam alloy (Tytin). Cylindrical specimens were prepared by dead-loading or hand-condensing amalgam in a Teflon mold which was unlined, lined with Panavia EX, or lined with Amalgambond. Compressive strength specimens were tested at 1 hour, 24 hours, and 7 days after preparation. Creep specimens were tested at 7 days. The adhesive resin liners did not significantly affect the strength of the Tytin specimens prepared by dead-loading (P greater than 0.05). The Panavia EX significantly reduced the strength of the Tytin specimens prepared by hand-condensing (P less than 0.05). The creep rate was not significantly affected by either resin liner.

Four resin veneering materials and four methods of retaining the veneer on metal castings were compared with metal ceramic restoration. Variations in microleakage were noted between the four resin materials retained by mechanical retention beads. When mechanical and chemical modes of a resin and porcelain veneer retention were compared, there was no microleakage with one mechanically and two chemically retained resin groups including one metal ceramic group. The resin materials tested understandably produced substantially lower shear bond strengths than the metal ceramic specimens. Higher shear bond strengths were recorded for the retentive beads than for the resins retained by three chemical bonding techniques. There was no direct correlation between microleakage and shear bond strength.

Four commercial bond agent-composite systems were tested with respect to the strength of the bond to bovine dentin and their ability to seal class 5 erosion lesions without cavity preparation. At seven days there was no significant difference in the bond strengths of the four bonding agents, Scotchbond, Gluma, Tenure, and Scotchbond 2. Restorations placed with Gluma had significantly less leakage than those placed with other bond agents. At 90 days the bond strength of Tenure was reduced and was significantly less than that of the other systems, while Gluma and Scotchbond 2 restorations exhibited significantly less leakage than Scotchbond and Tenure. There was an inverse correlation (r2 = .5460) between bond strength and marginal leakage of class 5 restorations.

Forty porcelain disks were resin bonded to etched base metal surfaces to measure tensile bond strengths. One metal surface was bonded to each porcelain surface, making each test specimen "sandwiched", with a porcelain disk between two metal surfaces. The mean bond strength values of the Conclude group was 3017 +/- 869 psi. The mean for the Mar-Bond group was 3747 +/- 693 psi, and the mean for the two Chameleon groups combined was 3172 +/- 544 psi. No two groups were significantly different.

The acceptance of simplified technical procedures that minimize clinical effort is exemplified by the popularity of direct bonding. This study (1) measured the comparative tensile bond strengths of brackets bonded directly in vitro to both glazed and deglazed porcelains by the use of five adhesive systems, and (2) recorded failure sites. System 1+, Enamelite 500, Isopast/Silanit, and Concise/Scotchprime proved to have strengths that should be acceptable clinically. Ultra-bond produced a bond that was significantly less in strength as compared with the other four systems. There was no significant difference in the bond of glazed and deglazed porcelains. Diamond polishing paste was better at restoring the porcelain surface to original smoothness in comparison with polishing stones. Irreversible damage to the porcelain surface may result from the bonding procedure.

Etching or roughening the surface of glass ionomer cement before use of composite resins and bond agents produces bond strengths comparable to the bond strength between glass ionomers and dentin. Bond failure at such surfaces occurs within the glass ionomer. Adequate washing with water after acid etching the glass ionomer is essential to obtain optimal bond strength. Apparently, some combinations of ionomer cements and resins are more effective than are others in providing a good bond in the "sandwich technique".

The purpose of this study was to evaluate and compare the strength of aluminous porcelain jacket crowns made in the following manners: (1) the conventional technique, (2) the conventional technique with a pure alumina insert, (3) the twin foil technique, and (4) the twin foil technique with a pure alumina insert. The conclusions of this investigation can be summarized as follows: 1. Porosity was observed in all the restorations made by each of the techniques. 2. The porosity was greater at the porcelain-platinum foil interface than anywhere else throughout the restoration with both the conventional and twin foil techniques. 3. The porosity seemed to be evenly distributed along the interface, with no concentration in any area. 4. Regardless of the technique, crowns that were more porous fractured at lower values. 5. Crowns built by the twin foil technique were significantly more porous at the interface of the tin-plated platinum and the porcelain core than those built by the conventional technique. 6. Crowns constructed with the conventional technique were significantly stronger than those constructed with the twin foil technique. 7. There was no bond between the core porcelain and the platinum foil matrix in crowns constructed by the conventional technique. 8. There seemed to be a strong bond between the core porcelain and the tin-plated platinum matrix in crowns built by the twin foil technique. 9. The presence or absence of the alumina insert on crowns constructed with the conventional and twin foil technique did not affect the strength of the crowns when tested at the incisal edge.