Adhesive bond strengths of glass ionomer and polycarboxylate cements to human enamel and dentine were measured in vitro on untreated surfaces and on surfaces treated with cement liquid or polyacrylic acid, ferric oxalate, and ferric chloride. The bond strengths of two cements to enamel and dentine were increased by as much as 183 per cent by the use of surface treatments of polyacrylic acid and ferric oxalate.

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The color and optical properties of three anterior and four posterior composites were determined from reflection spectrophotometric data and Kubelka's equations. Samples were aged for 300 hours at 43•Ž, 90% relative humidity, intermittent water spray, and continuous exposure to a 2500 watt xenon light. After aging the composites were generally darker, more chromatic, and more opaque. Values of S (absorption coefficient) and K (scattering coefficient) increased and values of XI (infinite optical thickness) decreased. The light-cured composites were less stable than the chemically cured ones.

The purpose of this study was to evaluate the effects of two concentrations of poly (acrylic acid) (10 and 25%), three treatments (untreated, passive conditioning, and active conditioning), and two storage conditions (24 hours in 37 degrees C water and thermal cycling) on the in vitro tensile bond strength of three commercial glass-ionomer liners to human dentin. Bond strengths to untreated dentin after storage for 24 hours ranged from 19.0 to 21.7 kg/cm2 for Glasionomer Base Cement, Cement/Liner, and Ketac-Bond, but dropped to a range of 4.9 to 9.7 kg/cm2 after thermal cycling. Active conditioning with 10% acid resulted in bond strengths after 24-hour storage that ranged from 23.5 to 44.0 kg/cm2, compared with values from 21.7 to 38.0 kg/cm2 with active conditioning using 25% acid. Active conditioning with 10% acid resulted in bond strengths after thermal cycling that were in the range of 15.8 to 27.4 kg/cm2 and were 80 to 320 percent higher than values resulting from passive conditioning under these conditions. Active conditioning with 10% acid for 30 seconds produced a bond strength for Glasionomer Base Cement of 44.0 kg/cm2, compared with a bond strength of 28.7 kg/cm2 for a 10-second active conditioning. Qualitative analysis of scanning electron photomicrographs showed that dentin tubules were opened to a greater extent by active conditioning with 25% acid than by passive conditioning with 10% acid.

The present paper investigates the convergence of some new implicit iterations of coupled fixed point for non-linear contractive like functions on W-hyperbolic metric spaces. Moreover, we provide a theoretical comparison of our new iterations to illustrate the fastest iteration the coupled fixed point.