The influence of water storage on durometer hardness of 5 soft denture liners over time.
OBJECTIVE
This laboratory study investigated the influence of water storage on the durometer hardness of 2 RTV and 3 HTV soft denture liners over a 1-year period.


METHODS
Five soft denture liners were used: 2 HTV silicone rubber (Luci-Sof and Molloplast-B), 1 RTV silicone rubber (Tokuyama), 1 HTV polyphosphazene (Novus), and an RTV plasticized acrylic (PermaSoft) that uses a surface sealer. They were processed following manufacturers' instructions, cured, and stored in tap water at 37 degrees C. The water was changed every 2 weeks. Five durometer A hardness measurements were made at logarithmically spaced intervals of 16.7 minutes, 27.8 hours, 11.6 days, 34.7 days, 115 days, and 347 days. Repeated measures analysis of variance (MANOVA), one-way analysis of variance (ANOVA), Pillai trace statistic, the difference scores (last-first) among the groups, and the Tamhane T2 multiple comparison test were used to compare the groups over time, all on SPSS V. 7.5 and 9.0.


RESULTS
The order of highest initial indentation hardness was Luci-Sof, Molloplast-B, Novus (H(D)= 38 to 33). Tokuyama and PermaSoft as a group were softer (H(D)= 18 to 22). Tokuyama Soft Relining changed the least over 347 days, followed by Luci-Sof, Novus, Molloplast-B, and PermaSoft in that order (p < or = 0.05). Within the PermaSoft group, sealer applied only once changed the least over 347 days, followed by no sealer, and then sealer applied every month (p < 0.0005).


CONCLUSIONS
After 347 days of water storage, Tokuyama had the lowest indentation hardness changes, followed by Luci-Sof, Novus, PermaSoft with sealer applied once; Molloplast-B, PermaSoft without sealer; and PermaSoft with sealer applied every month. All HTV soft denture liners had higher indentation hardness than RTV liners initially. After 347 days, PermaSoft without sealer and with sealer every month became the hardest.
Kiat-Amnuay
Sudarat
S
Department of Restorative Dentistry and Biomaterials, The University of Texas at Houston Dental Branch, USA.
Gettleman
Lawrence
L
Mekayarajjananonth
Trakol
T
Khan
Zafrulla
Z
Goldsmith
L Jane
LJ
D000704:Analysis of Variance; D001593:Benzyl Compounds; D003799:Dental Stress Analysis; D003822:Denture Liners; D004129:Dimethylpolysiloxanes; D006244:Hardness; D008422:Materials Testing; D008689:Methacrylates; D009943:Organophosphorus Compounds; D011108:Polymers; D012826:Silicone Elastomers; D013997:Time Factors; D014867:Water
D001593:Benzyl Compounds; D004129:Dimethylpolysiloxanes; C483699:Luci-soft; C020964:MDX 4-4210; D008689:Methacrylates; D009943:Organophosphorus Compounds; C098877:PermaSoft denture liner; D011108:Polymers; D012826:Silicone Elastomers; C108974:poly(phosphazene); C076789:polyphosphazene fluoroelastomer; C501646:tokuyama soft relining; D014867:Water