Ahmed A Elhejazi, Sulman Alsufayyan.
Colour differences between try-in-paste, light-cure and dual-cure resin cements used for luting laminate veneers.
J Pak Dent Assoc Jan ;16(1):30-4.

OBJECTIVE: The purpose of this study was to evaluate the effect of try-in paste shade on final resin luting cements on colour difference under porcelain laminate veneer. MATERIALS & METHODS: Variolink II Esthetic cementation systems; (Ivoclar Vivadent, Liechtenstein.) shade A1/110 was used in this study. This cement had two types of curing methods; the light activation and the dual activation polymerization. One shade (Al) of porcelain discs glass-ceramic (IPS-Empress 2) were prepared according to manufacture instruction. A total of 25 disks were prepared at size of 15 diameter xl mm thickness. Five discs were cemented with try-in- paste for control group shade A 1. A total of 20 specimens were distributed to four groups, five samples each: Group I: Light cured cement discs under clear Mylar matrix. Group II: Dual cured cement discs under clear Mylar matrix. Group III: Light cured cement discs with porcelain disc 1mm thick. Group IV: Dual cured cement discs with porcelain disc 1 mm thick. The cement used was either light cure or dual cure and was polymerized according to the manufacturer instructions under porcelain laminated veneer or Mylar matrix. All samples were subjected to measurement of colour by utilizing a spectrophotometer (Colour-Eye 7000A, Gretag Macbeth, New Windsor, NY, USA).The colour parameters were recorded in the L* a* b* colour space. RESULTS: Luting resin cements light cure and dual-cure under clear Mylar matrix had AE* values 13.40 and 13.07 respectively and no significant differences was observed between them. But under porcelain disc the values for light-cure and dual-cure resin cements had significant lower AE* values 6.48 and 6.83 respectively and there was no significant differences between them (p >0.05). All groups showed AE* values higher than 3.7 which means very poor match of colour (mismatch) comparing with control group. The results of Da* and Ab* red and blue axis indicate that all luting agents (light-cure and dual-cure) had shifted to wards darker shade (yellow and blue). CONCLUSION: Try-in paste and final luting resin cements had unacceptable colour differences (mismatch). Although they had the same shade as manufacture indicated.

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