The effect of the elastic modulus of endodontic posts on static load failure.

AIM: To compare posts of different flexibility using static load testing. Hypotheses tested were (1) the flexural modulus of endodontic posts does not show a linear relationship with failure load and (2) the flexural modulus of endodontic posts does not show an association with failure mode. METHODOLOGY: Thirty 2 mm diameter rods of a glass fibre material Aesthetiplus (A), a carbon fibre Composipost (C) and stainless steel (S) were cemented into 90 roots of extracted human teeth using resin cement. Composite resin cores were added and the roots embedded in self-curing acrylic resin. Samples were loaded at 90° in a universal testing machine until failure. Failure loads and fracture levels were compared using one-way anova and post-hoc Scheffé tests. Proportions of different failure modes were compared with Chi square tests (α = 0.05). RESULTS: Mean failure loads - MPa (SD) were A - 278.69 (85.79), C - 258.86 (82.05), S - 347.37 (74.50). There was no significant difference in the mean failure load of roots containing the FRC posts (P = 0.639), but it was significantly greater for steel post samples (P < 0.01). The mean level of fracture among the groups was not significantly different (P = 0.879). No root fractures were 'favourable'. Significantly more root fractures and fewer core fractures occurred for group A than for groups C or S (P < 0.01). CONCLUSION: The elastic modulus of an endodontic post does not appear to be a principal factor influencing load at failure or mode of failure of post-restored teeth.

Quantifying the strength of a resin-coated dental ceramic.

Resin luting all-ceramic restorations increases clinical performance; however, the strengthening mechanisms are not fully understood. The authors have previously proposed the existence of a resin-ceramic hybrid layer, and the hypothesis tested was that ceramic strength enhancement was conferred by the characteristics of the resin-ceramic hybrid layer. Dentin porcelain discs were polished with a P4000-grade abrasive paper, and half were centrally indented at 9.8 N. Further discs were alumina-air-abraded. Groups of 30 specimens were coated with resin cement thicknesses varying from 0 to 250 +/- 20 microm before bi-axial flexure testing. Following investigation of residual stresses by annealing, regression analysis enabled us to calculate the magnitude of 'actual' strengthening for a theoretical 'zero' thickness of resin cement on each surface texture. Accounting for resin bulk strengthening, resin cement coating significantly increased the mean strength that was attributed to a resin-ceramic hybrid layer sensitive to surface texture.

Water uptake and strength characteristics of a nanofilled resin-based composite.

OBJECTIVES: To investigate the influence of short- and medium-term immersion on water uptake and mechanical properties of a so-called 'nanofilled' compared with a conventional resin-based composite (RBC). METHOD: For each material (a microhybrid, Filtek Z250, FZ and 'nanofilled' RBC, Filtek Supreme in body and translucent shades, FSB and FST; 3M ESPE, St. Paul, USA) five specimen groups (n=20) were tested. Mean bi-axial flexure strength (BFS) of each group was determined following 24h 'dry' and 24h, 3, 6 and 12 months in a water-bath maintained at 37+/-1 degrees C prior to testing. The extent of water uptake following each storage regime was determined using a near-infrared spectroscopy (NIRS) technique. RESULTS: No significant difference in BFS was identified for each material stored dry or wet for 24h (F=2.7; P=0.07) whilst BFS decreased following 3, 6 and 12 months (F=6.6; P<0.001). A significant decrease in BFS of FZ was observed following 3 and 6 months (147+/-34 and 102+/-30 MPa; P<0.001) with no further reduction following 12 months (94+/-13 MPa; P>0.05). In contrast, no significant decrease in BFS of FSB (97+/-34 MPa) and FST (112+/-28 MPa) was recorded following 6 compared with 3 months immersion (P>0.05). Storage for 12 months resulted in a further significant strength reduction of FSB and FST (56+/-11, 82+/-12 MPa; P=0.004, P<0.001, respectively). Water uptake of FZ and FSB increased up to 3 months before equilibrating, whereas water content of FST increased following all storage periods. CONCLUSIONS: Strength degradation occurred at different rates between material types. Water uptake and mechanical properties of test materials were influenced by the size and morphology of the reinforcing particulate phase. The use of nanoparticles and associated agglomerates in modern RBCs exhibit distinct mechanical and physical properties compared with a conventional RBC type.

Resin elasticity and the strengthening of all-ceramic restorations.

Resin luting of all-ceramic restorations results in increased performance; however, the strengthening mechanism and the role of the mechanical properties of the resin are not fully understood. The hypothesis tested is that ceramic strength enhancement is dependent on the elastic modulus of the resin. Three-point flexural moduli of a flowable, luting, and hybrid composite resin were characterized. Two hundred forty porcelain discs were air-abraded. One group acted as a control, and 3 additional groups were coated with 120 +/- 20 microm of each resin prior to bi-axial flexure testing. All resins significantly increased in mean strength, and the associated strength increase was related to the elastic modulus of the resin (R(2) = 0.9885), so the hypothesis was accepted. The combination of Poisson constraint and the creation of a resin-inter-penetrating layer sensitive to the elastic modulus of the resin may provide an explanation of the strengthening mechanism.

Photoinitiation chemistry affects light transmission and degree of conversion of curing experimental dental resin composites.

INTRODUCTION: The effect of photoinitiator and co-initiator chemistry on the setting reaction and degree of conversion of dental resin-based composites (RBCs) has rarely been determined explicitly. This work examines the effect of type and concentration of photoinitiator and co-initiator on the rate of change of light transmission throughout polymerisation and degree of conversion of model RBC formulations. METHODS: Bisphenol-A diglycidyl ether dimethacrylate (bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) (6:4 molar ratio) resins filled with silanized glass filler (74wt.%) and containing various photoinitiators (camphorquinone; CQ, 1-phenyl-1,2-propanedione; PPD, benzil; BZ), co-initiator types (N,N-dimethyl-p-amino benzoic acid ethyl ester; DABE, N,N-cyanoethyl methylaniline; CEMA, N,N-diethanol-p-toluidine; DEPT) and concentration (0.0-0.3% DABE) were polymerised using a halogen or LED light curing-unit (LCU) for 10, 20 and 40s. The setting reaction was monitored in real-time by measuring the light transmittance through the curing specimen and bulk degree of conversion (DC) evaluated using Fourier transform infra-red spectroscopy. RESULTS: Specimens containing CQ and PPD cured with the halogen LCU did not have a significant effect on DC or changes in light transmission, although a significant increase in DC was observed for CQ compared with PPD specimens cured with the LED LCU. DABE and CEMA were more effective co-initiators than DEPT. Although DC was not limited by co-initiator concentration, the absence of a co-initiator resulted in marked differences in light transmission and decreased DC throughout 40s irradiation with each LCU type. CONCLUSIONS: The spectral range emitted from different types of LCU and absorption characteristics of the photoinitiator chemistry of light-activated resin-based composites play a critical role in the efficiency of polymerisation.

Marginal adaptation and micro-porosity of class II restorations of a high copper amalgam and a palladium-free gallium-based alloy.

The aim of the current investigation was to compare the marginal adaptation and internal porosity of a gallium (Ga)-based alloy (Galloy) with a high copper amalgam (Permite C DP) when used in moderately sized conventional class II cavities. Ten dentists placed two restorations of each material in standardized class II cavities in typodont teeth set in a phantom head. The proximal surfaces of the restored teeth were subsequently examined using an optical microscope and colour photographs were taken. The teeth were then serially sectioned before being re-examined microscopically and re-photographed. Three dentists rated the photographs of the restorations on two occasions, 2 weeks apart, for marginal adaptation and internal porosity using a six and five point scoring criteria, respectively. Inter- and intra-examiner agreements were assessed with weighted kappa statistics. The Ga-based alloy exhibited inferior marginal adaptation and a significantly higher level of porosity and internal defects compared with the dental amalgam. Marginal defects were mainly concentrated at the gingival third of the proximal boxes for both alloys. The poor marginal adaptation and extensive internal porosity detected for the Ga-based alloy was attributed to the difficulty in the alloy condensation related mainly to the 'stickiness' of the alloy to the condensers and to the rapid change in the plasticity of the alloy during condensation. This could possibly be a factor in the post-operative complications reported with the clinical use of this alloy.

The strengthening mechanism of resin cements on porcelain surfaces.

All-ceramic crowns bonded with resin cements have increased performance, and two theories have been proposed. Marquis (1992) suggested that the resin modified defects by crack healing, while Nathanson (1993) proposed that resin polymerization shrinkage strengthened porcelains. Both theories imply a sensitivity of strengthening to defect size. The hypothesis tested was that resin strength enhancement is independent of defect severity. We ground 200 porcelain discs to remove imperfections and indented 120 to create a large defect. Discs were tested dry, wet, and after being coated with 75-100 microm of resin cement in bi-axial flexure. Disc strength with and without indentations was increased significantly when coated with 2 resin cements. Both cements significantly increased the strength independent of defect population, and the hypothesis was accepted. It is proposed that the combination of surface pre-treatment and cement moved the fracture origin from the porcelain/cement interface to the cement surface, consistent with resin strength enhancement independent of defect severity.

The frictional coefficients and associated wear resistance of novel low-shrink resin-based composites.

OBJECTIVES: Frictional forces play a major role in the oral wear process of dental resin-based composites (RBCs) and it would be of interest to consider how the energy from friction is dissipated at the material surface. Consequently, the micromechanical wear properties of conventional methacrylate compared with novel oxirane RBCs were assessed. METHOD: The frictional coefficient (mu), volume loss and Vickers hardness number (VHN) of oxirane (EXL596 and H1) and methacrylate RBCs (Z100 and Filtek Z250) were evaluated. Archard's wear equation was implemented to obtain the wear coefficient (K) and expressed as a 'fraction of friction' (K/micro) to indicate the dissipation of frictional energy that resulted in wear. Scanning electron microscopy (SEM) was used to qualitatively asses the wear facets of each RBC following 50000-cycles. RESULTS: The mean frictional coefficients observed between the oxirane and methacrylate RBCs were not significantly different (P > 0.05). However, the volume loss of EXL596 and H1 (5.9 +/- 0.4 and 4.7 +/- 0.3 x 10(-2) mm(3)) was significantly increased compared with Z100 and Filtek Z250 (1.7 +/- 0.2 and 2.3 +/- 0.3 x 10(-2) mm(3)). The VHN of EXL596 and H1 was either significantly greater (P = 0.021) or similar (P = 0.089) to Filtek Z250, respectively. An increase in K/micro was reported for EXL596 and H1 (34.7 +/- 4.1 and 22.8+ /- 2.4 x 10(-4)) compared with Z100 and Filtek Z250 (8.50 +/- 0.7 x 10(-4) and 8.62 +/- 1.0 x 10(-4)) (P < 0.05). SEM images of the oxirane RBCs exhibited increased surface fatigue and delamination of the surface layers compared with the methacrylate RBC specimens following 50,000-cycles. CONCLUSION: The significant decrease in wear resistance of the oxirane compared with methacrylate RBCs was unexpected since frictional coefficients and/or surface hardness were statistically similar. The decreased wear resistance of EXL596 and H1 compared with Z100 and Filtek Z250 was further explained by the increase in K/micro from wear theory and the associated increase in surface fatigue identified from SEM. The simplistic testing procedure combined with SEM utilized in the current investigation provided a greater insight into the wear mechanism by considering the effect of frictional energy at the specimen surface which may benefit the development of improved wear resistance for experimental RBC materials.

The reliability of standardized flexure strength testing procedures for a light-activated resin-based composite.

OBJECTIVES: To investigate the differences in the reliability of three-point flexure strength (TFS) and bi-axial flexure strength (BFS) data of a dental resin-based composite (RBC) irradiated by a hand-held or an oven light-curing unit (LCU). METHODS: Three-point bar-shaped (25 x 2 x 2 mm3) and bi-axial disc-shaped (12 mm diameter, 2 mm thick) specimens of Filtek Z250 were polymerized utilizing either a hand-held (n = 20) or an oven-LCU (n = 20). The mean TFS and BFS, associated Weibull moduli and degree of conversion (DC) for each curing regime were obtained following 24 h immersion in a light-proof water bath maintained at 37 +/-1 degrees C. RESULTS: A significant decrease in TFS (129 +/- 15 and 127 +/- 13 MPa) compared with BFS (140 +/- 12 and 148 +/- 13 MPa) was identified for specimens irradiated with both LCU types (P < 0.001). The Weibull moduli of TFS data associated with the hand-held--was significantly decreased compared with the oven-LCU since confidence intervals did not overlap (7.5-9.4 and 9.5-10.6, respectively). In contrast, the Weibull moduli of the BFS data associated with either LCU were not significant (11.3-12.4 and 11.3-13.5). A significant decrease in the DC of three-point and bi-axial flexure specimens irradiated with the hand-held compared with the oven-LCU was reported (P = 0.031). CONCLUSIONS: The improved experimental reliability combined with the increased clinical relevance in specimen geometry of disc-compared with bar-shaped specimens may advocate bi-axial flexure testing methodology as the standard to assess the strength of light-activated dental RBCs. The differences in extent of polymerization of RBC specimens cured with either LCU were not consistent with an equivalent dose of light energy density. This phenomenon may be attributed to differences in polymerization efficiency associated with the quantity of useful light energy emitted from the hand-held--compared with the oven-LCU.

The influence of short and medium-term water immersion on the hydrolytic stability of novel low-shrink dental composites.

OBJECTIVES: Differences in mechanical and physical properties exhibited by novel low-shrink resin-based composite (RBC) formulations compared with conventional methacrylate RBCs may contribute to the clinical success of the candidate material. The aim of the current study was to investigate the effect of water uptake characteristics and water solubility on the mechanical properties of two methacrylate (Z100 and Filtek Z250), an experimental oxirane (OXI) and silorane (SIL) RBC following short- and medium-term immersion. METHODS: The water sorption/solubility and associated diffusion coefficients of each material (n=5) were measured using gravimetric analysis following short- (0.1, 0.5, 1, 4, 24 and 48 h) and medium-term (1, 4, 12 and 26w) immersion. The bi-axial flexure strength, associated Weibull moduli (n=20) and fracture analysis using scanning electron microscopy (SEM) of each material for similar immersion periods was also investigated. RESULTS: Following 0.5h and each subsequent short- and medium-term immersion period the water sorption of Z100 and Filtek Z250 was decreased compared with OXI. A significant decrease in bi-axial flexure strength and associated increase in filler particle exfoliation identified through SEM was identified for OXI compared with Z100, Filtek Z250 and SIL following 26w immersion. SIL exhibited the significantly lowest water sorption, solubility and associated diffusion coefficient following each immersion period. SIGNIFICANCE: The increase in water sorption, solubility and the associated diffusion coefficient of the experimental oxirane RBC, OXI was manifested as a significant decrease in bi-axial flexure strength and attributed to the decrease in synergy between the filler particles and resin matrix. The decreased water sorption, solubility and associated diffusion coefficient of the experimental silorane RBC, SIL may potentially improve hydrolytic stability of RBC restorations demonstrated by the non-significant decrease in bi-axial flexure strength following medium-term immersion.

Synthesis of nanophase hydroxyapatite by a Serratia sp. from waste-water containing inorganic phosphate.

Synthesis of nanophase hydroxyapatite (HA) on a bacterial surface was achieved at the expense of CaCl2 and inorganic phosphate (Pi). After initial nucleation, calcium was precipitated on and around the cells as calcium phosphate at the expense of inorganic phosphate in the challenge solution, with no precipitation in cell-free controls. HA was also biomanufactured using inorganic phosphate ions scavenged from a phosphate-containing waste-water. With additional Ca2+, the concentration of phosphate was decreased from 0.27 (approximately 25 ppm) to approximately 0.02 m (approximately 2 ppm) in the waste-water. Crystals of calcium phosphate manufactured by the cells were located by scanning electron microscopy (SEM) and identified as HA by X-ray powder diffraction, with an average crystal size calculated as approximately 25 nm. Possible application of bioHA as a biomaterial and implications for one-step 'waste-into product' are discussed.

Influence of filler loading on the two-body wear of a dental composite.

The purpose of the study was to explore the fundamental wear behaviour of a dental composite with different filler loadings under two-body wear conditions. The parent resin and filler components were mixed according to different weight ratios to produce experimental composites with filler loadings ranging from 20 to 87.5% by weight. A two-body wear test was conducted on the experimental composites using a wear-testing machine. The machine was designed to simulate the impact of the direct cyclic masticatory loading that occurs in the occlusal contact area in vivo. The results showed that there was little increase in the rate of wear with filler loadings below 60 wt%, but a sharp increase between 80 and 87.5 wt% in filler loading. Wide striations and bulk loss of material were apparent on the wear surfaces at higher filler loadings. Coefficients of friction increased with filler loading and followed the increase in rate of wear loss closely. It was concluded that, under two-body wear conditions, addition of high levels of filler particles into the resin matrix could reduce the wear resistance of dental composites. This finding may help when designing future dental composites for use in particular clinical settings.

Wear of three dental composites under different testing conditions.

Although a great effort has been made to date with research on in vitro wear simulation testing, it is difficult to identify the relationship between the results of in vitro testing and in vivo observations. An intensive study into wear mechanisms is necessary for wear testing simulation. The objective of this research was to study the wear behaviour of three selected dental composites under different wear conditions to provide a more rational explanation for their wear mechanisms. Two typical wear conditions, two- and three-body wear, were conducted on the composites. The results showed that the wear losses had different rankings between two wear conditions. It is therefore unreliable to predict the clinical performance merely by wear loss ranking from in vitro wear testing. Further analysis on the wear surfaces indicated that three dental composites experienced different wear mechanisms under different wear conditions. It is concluded that in vitro analysis of wear mechanisms may lead to a better understanding of in vivo failure patterns. Similar wear mechanisms should be the premise for any correlation between the results of in vitro and in vivo studies.

The effect of thermocycling on five adhesive luting cements.

The importance of bond strengths between dental luting cements and dental restorative materials has become increasingly important as a result of the adhesive technologies that have been developed over recent years. This study investigated the effect on tensile bond strength at the metal to cement interface for a semiprecious alloy for different prepared surfaces, cements and ageing regimes. At 24 h following preparation, silicoating and C & B Metabond appear to have distinct advantages in terms of interfacial bond strength, which was also noted after storage for 7 days in buffered saline. After thermocycling only silicoating conferred greater interfacial tensile strength, and any advantage that the 4-Methacryloxyethyltrimellitic anhydride (4-META) chemistry may have had at 24 h was no longer apparent. The poorest performing cement regardless of the ageing regime was Aquacem, although in relative terms its performance improved after 24 h. This preliminary investigation indicated that in vitro environmental ageing including thermocycling erodes the claimed advantages of some more novel dental adhesives. This may have important clinical consequences in their usage, although it must be appreciated that current thermocycling methodology may not be an accurate predictor of in vivo performance.

Influence of bonding agent composition on flexural properties of an Ultra-High Molecular Weight Polyethylene Fiber-Reinforced Composite.

This study evaluated the influence of seven commercially available bonding agents on the flexural properties of an Ultra High Molecular Weight Polyethylene (UHMWPE) Fiber-Reinforced Composite (FRC). Nine groups (n=10 per group) of flexural strength specimens were prepared from an indirect composite reinforced with UHMWPE fiber and cured according to manufacturers' instructions (Groups A to I). Group I was a fiber-reinforced negative control without any bonding agent resination. A tenth group (Group J) was a positive control group prepared using indirect composite alone. The fiber reinforcement material for Groups A to H was resinated with one of the seven different bonding agents. Group H used the same bonding agent as for Group G specimens. However, the fiber was silanized before bonding agent application for Group G specimens. Specimens were stored wet for 24 hours at 37 degrees C before measuring flexural strength and modulus in three-point bend at a crosshead speed of 1 mm/minute. Scanning Electron Microscopy (SEM) was employed to assess the fiber-resin interface of representative samples. The mean (SD) flexural strength of the test groups impregnated by the bonding agents ranged from 169 (37) to 266 (39) MPa. Statistical analysis of the flexural strength data using one-way ANOVA revealed significant (p<0.05) differences between the test groups. There was catastrophic fiber/composite failure in the positive control group that had a mean flexural strength of 75 (8) MPa. Silane pre-treatment of UHMWPE fiber before impregnation with the bonding agent significantly reduced the flexural strength (p<0.05).

Handling characteristics of a palladium-free gallium-based alloy compared with a high copper dental amalgam in a simulated clinical trial.

The aim of the current study was to compare the handling characteristics of a palladium-free gallium-based alloys (Galloy) with those of a high-copper amalgam (Permite C). The study had a particular interest in the evaluation of the direct placement delivery system used with both alloys. Ten dentists participated in the current study. Each placed two amalgam and two gallium-based alloy restorations in conventional class II cavities prepared in acrylic typodont teeth. None of the participating dentists had used the direct placement delivery system or had any previous experience with gallium-based alloy and no practice was allowed beforehand. The restorations were evaluated according to the following criteria: ease of loading the cavity (delivery system), ease of condensation, capacity to produce and sustain contact area, ease of carving, resistance to damage during removal of the matrix band, overall quality of the restoration and the available working time. Each criterion was given a score on a scale of 1-5 (1: very poor, 2: poor, 3: fair, 4: good, 5: very good). The results showed no statistically significant difference in the evaluated criteria between the two alloys (P > 0.05) except for criterion number 2 (ease of condensation, P=0.0005).

The influence of fibre placement and position on the efficiency of reinforcement of fibre reinforced composite bridgework.

The effect of placement of ultra-high molecular weight polyethylene (UHMWPE) fibres on the flexural properties and fracture resistance of a direct dental composite was investigated. The UHMWPE fibres are increasingly being used for the reinforcement of laboratory fabricated resin composite crown and bridgework. The aim of this study was to assess the effect of a commonly used laboratory fabrication variable on the in vitro strength of beam shaped specimen simulating a three-unit fixed bridge. Four groups (10 specimens per group) of Herculite XRV were prepared for flexural modulus and strength testing after reinforcement with UHMWPE fibres. Two groups of control specimens were prepared without any fibre reinforcement. Half the specimen groups were stored in distilled water and the other groups were stored dry, both at 37 degrees C for 2 weeks before testing. The results of this study showed that placement of fibre at or slightly away from the tensile side improved the flexural properties of the composite in comparison with the unreinforced control specimen groups whilst the mode of failure differed according to fibre position. Scanning electron microscope (SEM) investigation revealed that placement of the fibre slightly away from the tensile side favoured crack development and propagation within the resin bridging the interfibre spaces in addition to debonding parallel to the direction of fibre placement. Laboratory fabrication variables may effect the strength of fibre reinforced bridgework significantly.

An evaluation of the technique sensitivity of a hydrothermal low-fusing dental ceramic.

OBJECTIVES: To investigate the technique sensitivity in the manipulation of Duceram Low-Fusing Ceramic, a hydrothermal dental veneering material by employing bi-axial flexure tests. METHODS: Disc shaped specimens of Duceram-LFC dentine powder were condensed from varying powder contents manipulated with 0.33 ml of liquid. Bi-axial flexure (ball-on-ring) testing was employed to determine the mean bi-axial flexure strength, standard deviations and Weibull modulus (m). Apparent solid density and apparent porosity were also measured. RESULTS: Mean bi-axial flexure strengths and standard deviations of specimens condensed from 0.82 g of powder were 66.47 and 9.62MPa (m=7.23, 1.32) compared with 59.12 and 13.62 MPa (m=4.19, 0.77) and 63.91 and 14.51MPa (m=4.46, 0.81) for powder contents of 0.78 and 0.86 g, respectively. A decrease in apparent solid density and an increase in apparent porosity were also associated with increasing or decreasing the powder content of slurry consistencies. CONCLUSIONS: A slurry consistency was identified for Duceram-LFC specimens where the reliability of fracture strength data increased. The technique sensitivity in the manipulation of Duceram-LFC would appear to be confirmed due to the relatively small amount of powder required to complete the transition from a 'fluid' to a 'thick' slurry consistency compared with a conventional veneering dental porcelain.

Fracture resistance of anterior, posterior and universal light activated composite restoratives.

This investigation measured the fracture resistance of a wide range of currently available light-activated-composite restoratives. Products intended solely for anterior use were tested together with universal materials and products intended for posterior application. All materials were handled according to manufacturers' instructions. For products evaluated in this investigation, universal and posterior materials yielded higher mean torque to fracture (T) values overall in comparison to the anterior products. One Microfilled and two Polyglas filled products designated for posterior application yielded relatively modest mean fracture resistance values.

A comparison of the mechanical properties of a gallium-based alloy with a spherical high-copper amalgam.

OBJECTIVES: The aim of the present study was to investigate how the mechanical properties of a palladium free gallium-based alloy (Galloy) compare with a leading spherical high-copper amalgam (Tytin). METHODS: Cylindrical specimens were mechanically condensed, according to the ISO 1559:1986 standard, to measure compressive strength, Vickers hardness, static creep and dimensional change on setting. Disc and beam shaped specimens were manually prepared to assess the diametral tensile and flexural strengths of the investigated alloys. RESULTS: The mean hardness, 1h compressive fracture strength, 24 h diametral tensile and 24h flexural strengths of Galloy were significantly lower (P<0.001) than Tytin. No significant differences in modulus of elasticity, creep, dimensional change on setting, 24 and 168 h compressive fracture strength for the two alloys were identified. SIGNIFICANCE: The significant reduction in the 1 h mean compressive fracture strength and hardness identified for Galloy compared with Tytin possibly indicate a slower setting reaction in the gallium-based alloy. Manual condensation of the gallium-based alloy produced specimens with inferior mechanical properties possibly due to the increased likelihood of introducing voids within the test specimens. Previous reports indicating poor corrosion resistance and moisture sensitivity of gallium-based alloys highlight the need for further research to investigate the effect of the oral environment on the gallium-based alloy.