Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Shear Strength”

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

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

At least 217 records · Page 12Linked to original sources
PubMed2003

Effect of laboratory procedures and thermocycling on the shear bond strength of resin-metal bonding systems.

STATEMENT OF PROBLEM: During fabrication or repair of removable partial dentures, resin-to-metal or resin-to-denture tooth bonds may be stressed by laboratory procedures. PURPOSE: The purpose of this in vitro study was to evaluate the effect of steam cleaning, boiling, ultrasonic cleaning (laboratory procedures), and thermocycling on shear bond strength of resin bonds to metal and denture teeth. MATERIAL AND METHODS: Resin-metal bonding systems and their specific veneer resins (Rocatec, Sinfony; Rocatec, Visio-Gem, HLC-BOND, Zeta LC and Ducera experimental veneer resin) were tested on a Co-Cr alloy (Wirobond C). The veneer resins were bonded to resin denture teeth. The experimental groups (n=7) were subjected to the following conditions: 24-hour storage of the specimens in air (group I, control group), storage in air and treated with simulated laboratory procedures (2 minutes steam cleaning, 15 minutes ultrasonic cleaning at room temperature, 1 hour boiling in water, group II), storage in air with thermocycling (5000 cycles, 5 degrees to 55 degrees C, group III), storage in air with laboratory procedures followed by thermocycling (group IV), and storage in air with thermocycling followed by laboratory procedures (group V). Shear strength tests (MPa) were performed with a universal testing machine until fracture. After shear bond testing, the failure mode of the resin-metal and resin-denture tooth bonds was assessed. Statistical analysis of the results was carried out with one-way analysis of variance and Bonferroni-Dunn's multiple comparisons post hoc analysis for test groups (alpha=0.05). RESULTS: Except for Ducera/denture tooth specimens (groups III to V: 8.7 +/- 3.4-9.1 +/- 1.7; 10.8 +/- 1.9 MPa control group), the Wirobond C and denture tooth specimens (groups III, IV and V: 1.4 +/- 0.9-11.9 +/- 2.3 MPa), showed significantly lower shear bond strengths than the corresponding control groups (7.5 +/- 2.9-21.0 +/- 3.4 MPa, P<.05). The shear bond strengths of group II of Sinfony/Wirobond C (11.6 +/- 3.3 MPa, P<.0001), Visio-Gem/Wirobond C (7.4 +/- 1.9 MPa, P<0.0001), Ducera/Wirobond C (11.8 +/- 2.9 MPa, P<.0001) and of Zeta/denture tooth (3.9 +/- 1.6 MPa, P=.0005) were significantly decreased by steam, boiling, and ultrasonic procedures compared with the corresponding control groups (21.0 +/- 3.4 MPa; 14.7 +/- 4.0 MPa; 19.1 +/- 2.3 MPa; 7.5 +/- 2.9 MPa, respectively). No significant differences were noted among groups III, IV, and V. Co-Cr specimens subjected to the Rocatec system and bonded with Sinfony and HLC BOND/Zeta specimens showed cohesive failure. Adhesive failure was observed for the experimental veneer resin on the Co-Cr specimens and for all veneer resins on the denture teeth. CONCLUSION: Simulation of laboratory procedures and thermocycling caused a significant drop in shear bond strength of metal-resin and denture tooth-resin bonds for most of the tested veneer resins. Thermocycling before shear testing had the same effect on veneer resin bond strength as the simulated laboratory procedures.

Acrylic Resins↗
PubMedDate not supplied

[Influence of post-fixation time on shear bond strength of brackets fixed with different materials].

The purpose of this study was to evaluate the shear bond strength of four bonding materials for brackets, 10 minutes and 24 hours after their fixation, as well as the kinds of fracture observed. The buccal surfaces of 32 premolars were etched for 30 seconds with 35% phosphoric acid, and brackets were bonded using Orthodontic Concise (3M) and Z100 (3M). In other 32 premolars, brackets were bonded with Fuji I (GC) and Fuji Ortho LC (GC) on the buccal surfaces, without acid etching. After the bonding procedures, 32 samples were stored in distilled water at 37 degrees C for 10 minutes, and 32 samples were stored at the same temperature for 24 hours. The samples were then submitted to shear bond strength testing in an Instron testing machine, at a crosshead speed of 0.5 mm/min. The results were submitted to ANOVA and Tukey's test (p < 0.05). The results indicated that, for 10 minutes and 24 hours, Orthodontic Concise showed shear bond strength values (6.22 and 7.73 MPa, respectively) higher than Fuji Ortho LC (3.32 and 5.10 MPa), Z100 (2.72 and 4.51 MPa) and Fuji I (2.52 and 4.54 MPa). No statistical difference was verified between Fuji Ortho LC, Z100 and Fuji I (p < 0.05). In conclusion, Orthodontic Concise showed better shear bond strength values than the other three bonding materials, for both 10-minute and 24-hour storage periods; the shear bond strength averages were higher for the storage time of 24 hours, for all tested materials, and a great number of adhesive fractures were observed in the specimens which received Fuji I, Orthodontic Concise and Z100.

Composite Resins↗
PubMed2005

Effect of light-tip distance on the shear bond strengths of composite resin.

The purpose of this study was to assess the effect of light-tip distance on the shear bond strength and failure site of brackets cured with three different light curing units: a high-intensity halogen (Astralis 10, 10-second curing), a light-emitting diode (LED, e-Light, six-second curing), and a plasma arc (PAC System, four-second curing). One hundred and thirty-five bovine permanent mandibular incisors were randomly allocated to nine groups of 15 specimens each. Stainless steel brackets were bonded with a composite resin to the teeth, and each curing light was tested at zero, three, and six mm from the bracket. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength. When the three light curing units were compared at a light-tip distance of zero mm, the three lights showed no significantly different shear bond strengths. At light-tip distances of three and six mm, no significant differences were found between the halogen and plasma arc lights, but both lights showed significantly higher shear bond strengths than the LED light. When evaluating the effect of the light-tip distance on each light curing unit, the halogen light showed no significant differences between the three distances. However, the LED light produced significantly lower shear bond strengths at a greater light-tip distance, and the plasma arc lamp showed significantly higher shear bond strengths at a greater light-tip distance. In hard-to-reach areas, the use of PAC system is suggested, whereas the LED evaluated in this study is not recommended.

Acrylic Resins↗
PubMed2002

Shear bond strength of enamel surface treated with air-abrasive system.

The aim of this study was to evaluate the shear bond strength of a composite resin to dental enamel, using three different surface treatments. Fifteen sound third molars were randomly assigned to three groups. The mesial and distal surfaces were flattened and covered using adhesive tape with a central orifice delimiting the adhesion area (7.07 mm2). Group I, the enamel surface was conditioned with 37% phosphoric acid for 15 s; group II, the surface was treated using air abrasion with aluminum oxide; group III, the enamel surface was treated using an association of air abrasion with aluminum oxide and 37% phosphoric acid. The Single Bond (3M) adhesive system was applied and a Teflon matrix was placed and filled with composite resin Z-100 (3M) and light-cured. The shear bond strength test was performed with a universal testing machine. The acid etching technique and air abrasion with aluminum oxide associated with acid etching had the highest shear bond strength values. Data were subjected to statistical analysis using ANOVA and the Turkey test, and no statistically significant difference in shear bond strength was observed between group I (12.49 +/- 2.85 MPa) and group III (12.59 +/- 2.68 MPa). In contrast, both groups had statistically better shear bond strengths compared to group II (0.29 +/- 0.56 MPa; p < 0.05). Air abrasion with aluminum oxide does not substitute acid etching. The association of these methods to obtain adequate adhesion to the substrate is necessary.

Acid Etching, Dental↗
PubMedDate not supplied

The influence of salivary contamination on shear bond strength of dentin adhesive systems.

This study evaluated the influence of salivary contamination during dentin bonding procedures on shear bond strength and investigated the effect of contaminant-removing treatments on the recovery of bond strength for two dentin bonding agents. One hundred and ten human molars were embedded in cylindrical molds with self-curing acrylic resin. The occlusal dentin surface was exposed by wet grinding with #800 silicon carbide abrasive paper. The teeth were divided into five groups for One-step (OS) (BISCO, Inc) and six groups for Clearfil SE Bond (SE) (Kuraray Co, Ltd, Osaka, Japan). For One-step, the grinding surface was treated with 32% phosphoric acid; BAC (BISCO Inc) and divided into five groups: OS control group (uncontaminated), OS I (salivary contamination, blot dried), OS II (salivary contamination, completely dried), OS III (salivary contamination, wash and blot dried) and OS IV (salivary contamination, re-etching for 10 seconds, wash and blot dried). For SE bond, the following surface treatments were done: SE control group (primer applied to the fresh dentin surface), SE I (after salivary contamination, primer applied), SE II (primer, salivary contamination, dried), SE III (primer, salivary contamination, wash and dried), SE IV (after procedure of SE II, re-application of primer) and SE V (after procedure of SE III, re-application of primer). Each bonding agent was applied and light cured for 10 seconds. Clearfil AP-X (Kuraray Co, Ltd) composite was packed into the Ultradent mount jig mold and light cured for 40 seconds. The bonded specimens were stored for 24 hours in a 37 degrees C waterbath. The shear bond strengths were measured using an Instron testing machine (Model 4202, Instron Corp). The data for each group were subjected to one-way ANOVA followed by the Newman-Keuls test to make comparisons among the groups. The results were as follows: In the One-step groups, the OS II group showed statistically significant lower shear bond strength than the OS control, I, III and IV (p<0.05). In the Clearfil SE Bond groups, the SE II and SE III groups had decreased shear bond strength compared with the control and SE I, SE IV and SE V groups (p<0.05). In conclusion, when using One-step total etch adhesive and when the etched surface is contaminated by saliva, blotting the surface and applying the primer can recover the bond strength. Complete drying of the salivary contaminated surface should be avoided. In the Clearfil SE Bond groups, the re-priming treatment (SE IV and SE V) resulted in the recovery of shear bond strength in the specimens contaminated after priming.

Analysis of Variance↗
PubMed2006

Self-etching bonding systems: in-vitro shear bond strength evaluation.

The purpose of this in vitro study was to compare the dentine shear bond strength of five self-etching bonding agents with that of a total-etch dentine bonding agent (used as control). Sixty recently extracted third molar teeth were mounted in acrylic resin and the occlusal surfaces ground to expose superficial dentine. A standardised smear layer was created by polishing with wet 600-grit SiC paper. Products evaluated were Xeno III (XIII), Clearfil SE Bond (SE), ABF (ABF), Optibond Solo Self-etch (OS), Adper Prompt-L-Pop (PLP) and the control, Scotchbond Multipurpose Plus (SBMP). Resin stubs were bonded to the dentine using the bonding agents according to manufacturer's instructions. Composite stubs were manufactured using an Ultradent jig and two increments of Z100, A1 shade composite. The bonds were subsequently stressed to failure with an Instron testing machine, operating at a crosshead speed of 0.5 mm/min. The data was statistically analysed using ANOVA (alpha < or = 0.05). The mean SBS (MPa) were: SBMP (Control) = 24.1 +/- 7.6; XIII = 17.3 +/- 4.1; SE = 26.2 +/- 7.8; ABF = 25.9 +/- 4.3; OS = 21.9 +/- 3.9 and PLP = 15.4 +/- 3.1. The shear bond strengths of both XIII and PLP to dentine were significantly lower than the control SBMP (p < 0.05). The remaining three products (SE, ABF and OS) displayed bond strengths comparable to the control (p > 0.05). Further research into cut (ground) and un-cut (un-ground) enamel shear bond strength and micro-leakage using these bonding agents are needed.

Analysis of Variance↗
PubMed2003

Shear bond strengths of composite bonded to porcelain using porcelain repair systems.

PURPOSE: To measure and compare the shear bond strengths to porcelain of two composites used with each of two different porcelain bonding systems. METHODS: 40 porcelain specimens were mounted in acrylic resin, ground flat using 120 and 320 grit sandpaper, and randomly divided into four groups of 10 for specimen fabrication as follows: Group 1: Premier MicroDose Porcelain Bonding/Optibond FL adhesive/Prodigy composite; Group 2: Premier MicroDose Porcelain Bonding/PQ1 adhesive/Amelogen composite; Group 3: Ultradent Porcelain Etch/Optibond FL adhesive/Prodigy composite; Group 4: Ultradent Porcelain Etch/PQ1 adhesive/Amelogen composite. Manufacturers' directions were followed to treat the porcelain surface and apply the adhesive and composite to each specimen. Following storage in distilled water at 37 degrees C for 7 days, the specimens were subjected to shear testing using an MTS 858 Universal Testing Machine. Data were recorded and analyzed using a one-way ANOVA and t-test. RESULTS: There was no significant difference in mean shear bond strength among the four groups (P = 0.575) or between the two groups with the highest and lowest mean shear bond strength (P = 0.288). The mean shear bond strength for all groups exceeded 21 MPa and 39 of 40 specimens exhibited cohesive fracture in porcelain.

Acid Etching, Dental↗
PubMed2004

Evaluation of shear bond strength at the interface of two porcelains and pure titanium injected into the casting mold at three different temperatures.

STATEMENT OF PROBLEM: Titanium has physical and mechanical properties, which have led to its increased use in dental prostheses despite casting difficulties due to high melting point and formation of oxide layers which affect the metal-ceramic bond strength. PURPOSE: This in vitro study evaluated the shear bond strength of the interface of 2 dental porcelains and pure titanium injected into a mold at 3 different temperatures. MATERIAL AND METHODS: Using commercially pure (cp) titanium bars (Titanium, Grade I) melted at 1668 degrees C and cast at mold temperatures of 430 degrees C, 700 degrees C or 900 degrees C, 60 specimens were machined to 4 x 4 mm, with a base of 5 x 1 mm. The 4-mm surfaces were airborne-particle abraded with 100 microm aluminum oxide before applying and firing the bonding agent and evaluating the 2 porcelains (Triceram/Triline ti and Vita Titankeramik). Ten specimens were prepared for each temperature and porcelain combination Shear bond testing was performed in a universal testing machine, with a 500-kg load cell and crosshead speed of 0.5 mm/min. The specimens were loaded until failure. The interfaces of representative fractured specimens of each temperature were examined with a scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Data for shear bond strength (MPa) were statistically analyzed by 2-way ANOVA and the Tukey test (alpha=.05). RESULTS: The results showed significant differences for the metal/porcelain interaction effect (P=.0464). There were no significant differences for the 2 porcelains (P=.4250). The Tukey test showed a significant difference between the pair cp Ti 430 degrees C Triceram and cp Ti 900 degrees C Triceram, with respective mean values and SDs of 59.74 +/- 11.62 and 34.03 +/- 10.35 MPa. CONCLUSION: Triceram porcelain showed a bond strength decrease with an increase in the mold temperature for casting titanium. The highest bond strength for Vita porcelain and the best metal-ceramic interface observed with the SEM were found with the mold temperature of 700 degrees C.

Air Abrasion, Dental↗
PubMed2003

Tensile and shear bond strength of resin-reinforced glass ionomer cement to glazed porcelain.

The purpose of this study was to measure the tensile and shear bond strength of resin-reinforced glass ionomer cement (RGIC) to glazed porcelain, to evaluate the durability of RGIC by thermal cycling, and to examine the RGIC remaining on the surface of the porcelain after the bond strength test to evaluate bonding conditions. Three adhesives were used in this study: Concise (CO) as a chemically cured composite resin, Fuji ORTHO (FO) as a chemically cured RGIC, and Fuji ORTHO LC (FOLC) as a light-cured RGIC. Tensile and shear bond strengths were measured 24 hours after bonding orthodontic brackets and also after thermal cycling. Tensile bond strength after 24 hours was 6.6 +/- 3.2 MPa in CO, 7.3 +/- 1.4 MPa in FO, and 8.6 +/- 1.9 MPa in FOLC, and the strength significantly decreased after the thermal cycling test. Shear bond strength after 24 hours was 32.5 +/- 8.9 MPa in CO, 23.3 +/- 6.8 MPa in FO, and 24.7 +/- 6.5 MPa in FOLC, and in contrast to tensile bond strength, no decreases in the strength were detected after the thermal cycling test. CO showed significantly higher shear bond strength than did FO and FOLC. When using the shear bond strength test and CO, destruction of porcelain surfaces frequently occurred after 24 hours and was observed in every specimen after the thermal cycling. RGIC was found to be an advantageous alternative to resin adhesive for bracket bonding to porcelain and to enamel.

Acrylic Resins↗
PubMed1992

Comparison of the shear bond strength of a titanium composite resin material with dentinal bonding agents versus glass ionomer cements.

This study compared the in vitro shear bond strength of an autopolymerizing composite resin system (CR) (Ti-Core) with two third-generation dentinal bonding agents (DBA) (Tenure and Scotchbond 2) to glass ionomer cements (GIC) (Ketac-Silver, GC Miracle Mix, and Ketac-Cem). The experiment was divided in five groups. The shear bond strengths were evaluated on a universal testing apparatus at three different intervals; 15 minutes, 24 hours, and 7 days. Statistically, (two-way analysis of variance), the shear bond strengths from the greatest to least were: Ti-Core CR with Tenure DBA > Ti-Core CR with Scotchbond 2 DBA > Ketac-Silver GIC, GC Miracle Mix GIC > Ketac-Cem GIC. There were no differences in shear bond strengths according to time, and no interactions between groups and time. The shear bond strengths for Tenure DBA with Ti-Core CR were two and a half to three times greater than the silver-filled glass ionomers, Ketac-Silver GIC and GC Miracle Mix GIC. Tenure DBA with Ti-Core CR also had consistently greater shear bond strengths than Scotchbond 2 DBA with Ti-Core CR, and this trend is in agreement with similar research.

Cermet Cements↗
PubMed1996

Relative shear bond strength and microleakage of two dentine bonding agents.

We determined the relative shear bond strength (SBS) to dentine and cementum and the microleakage of All-Bond 2 universal dental adhesive and OptiBond multi-use filled adhesive. We found that for both systems the SBS increased significantly (p < 0.001) from 15 minutes to 24 hours and 7 days, but there was a slight significant (p < 0.001) weakening towards 30 days. At each time point the shear bond strength of All-Bond 2 and OptiBond were also compared and it was found that OptiBond had significantly higher values (p < 0.05) at all times except at 15 minutes. Optibond also had the lower value for the microleakage (p < 0.001). This study showed that OptiBond had significantly higher shear bond strengths to and lower microleakage in dentine which may increase the longevity of the material in the clinical situation.

Dental Leakage↗
PubMed2003

[Comparison on shear bond strength of Edgewise brackets bonding with three orthodontic adhesives against salivary contamination].

OBJECTIVE: To compare the shear bond strength and ARI score of Edgewise brackets bonding with three adhesives under moist and dry conditions after salivary contamination. METHODS: Sixty extracted human premolars were randomly and equally divided into 3 groups. Edgewise brackets were bonded directly with composite resin, super bond C&B and single component adhesive under moist and dry conditions after salivary contamination. The shear bond strength and ARI score were measured and recorded. RESULTS: The shear bond strength of Edgewise brackets bonding with composite resin and single component adhesive under moist condition after salivary contamination decreased significantly and it can't meet the requirement of orthodontic therapy (6-8 MPa) while that under dry condition can. Super bond C&B can meet the requirement of orthodontic therapy on both conditions. CONCLUSION: Super bond C&B can be used under both moist and dry conditions after salivary contamination. Composite resin and single component adhesive can only be used under dry condition after salivary contamination.

Dental Bonding↗
PubMed2002

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

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

Acid Etching, Dental↗
PubMedDate not supplied

Shear bond strength of porcelain laminate veneer bonded with flowable composite.

This study evaluated the "in vitro" shear bond strength of two materials to bovine enamel when used as porcelain laminate veneer bonding systems. The authors used the dual-cured resin cement Variolink II (Vivadent) and the light-cured flowable composite Natural-Flow (DFL). Porcelain cylinders were bonded to bovine enamel following manufacturers' directions. After 24 hours of storage in distilled water and thermocycling, the specimens were tested on a universal testing machine to determine the shear bond strengths. Mean strengths found in Groups 1 (resin cement) and 2 (flowable composite) were not statistically different (p < or = 0.05). The authors concluded that the shear bond strength of Natural-Flow is not different from Variolink II and that flowable composites can be a suitable alternative when used as porcelain laminate veneer bonding systems.

Animals↗
PubMed1990

Shear bond strength of light-cured glass ionomer to enamel and dentin.

The shear bond strengths of a light-cured glass-ionomer cement to enamel and dentin were determined with use of extracted human maxillary permanent canines and molars. Bonding sites on the ground, etched enamel and ground dentin surfaces were demarcated by the punching of a hole, 3 mm in diameter, in an adhesive tape. The mixed glass-ionomer cement was transferred to the demarcated site, cured by exposure to visible light for 30 s, and the cement surface treated with Scotchprep Dentin Primer followed by Scotchbond 2 Light Cure Dental Adhesive. The embedded teeth were positioned in an assembly apparatus, and Silux composite was bonded to the glass-ionomer-cement surfaces. The specimens were disassembled after 15 min and subjected to a shear load (in an Instron machine) immediately after disassembly; after storage in water at 37 degrees C for 24 h, without and with temperature cycling; and after storage in water for four weeks, without and with temperature cycling. The shear bond strength of the glass-ionomer cement to etched enamel was in the order of 12 MN.m-2, and to dentin it was 9 MN.m-2. Temperature cycling and duration of storage had no adverse effect on the shear bond strength. The enamel and dentin aspects of fractured test specimens were examined, and the percentage of the bonding area that failed in the cement was estimated. Most of the test specimens failed partly at the enamel and dentin interfaces and within the glass-ionomer cement.

Analysis of Variance↗
PubMedDate not supplied

Effects of lining materials on shear bond strength of amalgam and gallium alloy restorations.

In this in vitro study, where alloys were condensed into unset paste lining materials, shear bond strengths were significantly greater than with the unlined controls. The use of varnish or Paama 2 linings did not significantly increase the shear bond strength of amalgam or gallium alloy restorations. The use of Vitrabond, Vitremer, or Resinomer liners significantly increased the shear bond strength compared to unlined restorations. Permite C restorations lined with Resinomer all showed cohesive failure within the mixed alloy/ liner. Of the unlined restorations, Permite C had significantly higher shear bond strength than Lojic Plus. The experimental method used in the present study proved to be suitable for quantitative comparison of the shear bond strength of different dental materials.

Analysis of Variance↗
PubMedDate not supplied

The effect of amalgam surface preparation on the shear bond strength between composite and amalgam.

The aim of this study was to investigate the effect of amalgam surface preparation on the short-and long-term in vitro shear bond strength between a dental amalgam (Valiant) and two dental composites (Herculite, Z100) mediated by three universal bonding agents (All-Bond 2, Amalgambond, and Scotchbond Multi-Purpose). Cylinders of dental composite resin were formed on, and bonded to flat amalgam surfaces. Prior to bonding, the amalgam surfaces were: a) ground flat, with the grinding lines oriented parallel to the direction of the shear stress; b) ground flat, with the grinding lines oriented perpendicular to the direction of the shear stress; or c) ground flat and then sandblasted using 50 micrometer Al2O3. A computerized Universal Testing Machine was used to determine the 1-, 7-, and 30-day shear bond strength of 162 samples (six per group) that were stored in distilled water at 37 degrees C. The results, which were statistically analyzed by performing a three-way analysis of variance (ANOVA) and 27 one-way ANOVA followed by modified (Bonferroni) t-tests for between-group comparisons (alpha = 0.05), have shown that: 1) sandblasting resulted in higher shear bond strength than grinding, except for 1-day All-Bond 2, where no differences were identified; 2) there was no difference in the shear bond strength between samples with parallel or perpendicular ground surfaces for a given bonding system and storage time; 3) for All-Bond 2, the 7-day shear bond strength of parallel and perpendicular ground samples dropped to half of the 1-day values, while the sandblasted samples showed a constant, high shear bond strength over 30 days, 4) for Amalgambond, the shear bond strength of parallel, perpendicular, and sand blasted samples was constant over 30 days; and 5) for Scotchbond Multi-Purpose, a sharp drop in the 7-day shear bond strength was recorded for all the samples, irrespective of amalgam surface preparation.

Composite Resins↗
PubMed1985

An evaluation of variables influencing implant fixation by direct bone apposition.

A systematic mechanical and histologic evaluation of design variables affecting bone apposition to various biocompatible materials was undertaken. The variables investigated included material elastic modulus, material surface texture, as well as material surface composition. The implant materials included polymethylmethacrylate (PMMA), low-temperature isotropic (LTI) pyrolytic carbon, commercially pure (C.P.) titanium, and aluminum oxide (Al2O3). Implant surface texture was varied by either polishing or grit-blasting the various materials. Implant surface composition was varied by applying a coating of ultra-low temperature isotropic (ULTI) pyrolytic carbon to the various implants. A total of 12 types of implants were evaluated in vivo by placement transcortically in the femora of adult mongrel dogs for a period of 32 weeks. Following sacrifice, mechanical push-out testing was performed to determine interface shear strength and interface shear stiffness. The results obtained from mechanical testing indicate that for implants fixed by direct bone apposition, interface stiffness and interface shear strength are not significantly affected by either implant elastic modulus or implant surface composition. Varying surface texture, however, significantly affected the interface response to the implants. For each elastic modulus group the roughened surfaced implants exhibited greater strengths than the corresponding smooth surfaced implants. Undecalcified histologic evaluation of the implants demonstrated that the roughened implants exhibited direct bone apposition, whereas the smooth implants exhibited various degrees of fibrous tissue encasement. Thus, for implants utilizing direct bone apposition fixation, it appears that of the parameters investigated, implant surface texture is the most significant.

Aluminum Oxide↗