The purpose of this study was to evaluate the color changes of the composite resin resulting from xenon lamp exposure in different environments. Composite resin (Z 250 ; shade A1, A2, A3, A3.5, and A4) were applied in a cylindrical metal mold. Seventy five specimens according to environments of exposure were made as follows;

Group I: aluminum foiling of the specimens in the air at 37℃ for 1 day and 7 days.

Group II: exposure of xenon lamp to the specimens in the air at 37℃ for 1 day and 7 days.

Group III: exposure of xenon lamp to the specimens in distilled water at 37℃ for 1 day and 7 days.

The color characteristics (L^*,a^*,b^*) of the specimens before and after exposure of xenon lamp were measured by spectrophotometer and the total color differences (ΔE^*) were computed.

The results obtained were as follows:

In all groups except A1 shade of group III, the ΔE^* values presented below 2.0, and group III showed the highest ΔE^* values followed by group II and group I in a decreasing order(p<0.05).

The purpose of this study was to evaluate the effect of salivary contamination of teeth on bonding efficacy of self-priming and self-etching DBSs. The materials used were Single Bond(SB, self-priming system, 3M), Unifil Bond(UB, self-etching system, GC), and Scotchbond Multi-Purpose Plus(SM, 3M) as control. Forty five human molars randomly allocated to three groups as dentin bonding systems tested and embedded in epoxy resin. Then the specimens were wet-ground to expose flat buccal enamel surface or flat occlusal dentin surface and cut bucco-lingually to form two halves with slow speed diamond saw. One of them was used under non-contamination, other under contamination with saliva. The bonding procedure was according to the manufacturer's directions and resin composite(Z-100, 3M Dental Products, St. Paul, MN) was built-up on the bonded surface 5mm high. The specimens were ground carefully at the enamel-composite interface with fine finishing round diamond bur to create an hour-glass shape yielding bonded surface areas of 1.5±0.1mm². The specimens were bonded to the modified microtensile testing apparatus with cyanoacrylate, attached to the universal testing machine and stressed in tension at a CHS of 1mm/min.. The tensile force at failure was recorded and converted to a tensile stress(MPa). Mean values and standard deviations of the bond strength are listed in table. One-way ANOVA was used to determine significant difference at the 95% level.

The bond strength of SBMP and SB were not affected by salivary contamination, but that of UB was significantly affected by salivary contamination. These results indicate that DBSs with total etch technique seems less likely affected by salivary contamination in bonding procedure.

The objectiveness of this study was to evaluate whether low-viscosity composite can bond effectively to dentin surface without bonding resin. The low-viscosity composites being 50wt% filler content were made by the inclusion of bonding resin of two self-etching systems(Clearfil SE Bond, Unifil Bond) varied with contents as 0, 10, 20, 30, 40, 50wt%.

Exposed dentin surfaces of extracted 3rd molars are used. Dentin bond strengths were measured. The tests were carried out with a micro-shear device placed testing machine at a CHS of 1mm/min after a low-viscosity composite was filled into an iris cut from micro tygon tubing with internal diameter approximately 0.8mm and height of 1.0mm.

Flexural strength and modulus was increased with the addition of bonding resin.

Low viscosity composite including some functional monomer may be used as dentin bonding resin without an intermediary bonding agent. It makes a simplified bonding procedure and foresees the possibility of self-adhesive restorative material.

The purpose of this study was to compare shear bond strength and interfacial pattern of composite bonded to dentin using self-etching adhesive systems.

Sixty extracted human molars with exposed occlusal dentin were divided into four groups and bonded with four adhesives and composites: Single Bond/Filtek Z 250(SB), Tyrian SPE-One-Step Plus/Aelitefil(TY), Prompt L-Pop/Filtek Z 250(LP), and One-Up Bond F/Palfique Toughwell(OU).

The results of this study were as follows;

Shear bond strength for OU was significantly lower than that of other groups(p<0.05). No significant difference was founded among SB, TY, and LP.

This study is to investigate the canal system in the mesiobuccal root of the maxillry first molar.

61 maxillary first molars were randomly selected. Serial transverse sections were made perpendicular to the long axis of the mesiobuccal root. Each section was placed in 3% sodium hypochlorite for 24 hours and rinsed in water and dried. The resected surface was stained with 2% methylene blue dye and examined with stereomicroscope.

Canal configuration analysis showed that 36.1% of the specimen classified as type I, 16.4% as type II, 37.7% as type III and 9.8% as type IV.

63.9% of the mesiobuccal root of maxillary first molar had two canaland 76.5% of sections with two canals in 5 MM had an isthmus. Because of this complexity the clinician should always search for extra canal carefullyand root canal system, including an isthmus, should be cleaned and shaped completelyand obturated three dimensionally for successful endodontic treatment.