Inlay leakage is strongly influenced by material, cement and tooth substrate

Objectives: Although cast gold had long been the material of choice for indirect inlay restoration, a wide variety of materials and cements are now available. Resistance to leakage is key to long term clinical success. This may be influenced by the inlay material, cement, and tooth substrate, enamel or dentin. The purpose of this in vitro study was to evaluate the influence of inlay material, cement, and tooth substrate on microleakage
Methods: Standardized Class II MO inlay preparations were made in 36 freshly extracted teeth, some margins being placed in enamel and others in dentin. Inlay materials included: IPS e.max (glass-ceramic, Ivoclar); VITA Enamic (interpenetrating network resin ceramic composite, Vita-Zahnfabrik); Lava Ultimate (processed resin-composite, 3M-ESPE); and JRVT High-Noble gold alloy (Jensen Dental). Gold inlays were impressed and cast conventionally; the other inlays were fabricated using digital impressions and CAD-CAM (CEREC 3, Sirona). Cements included: Panavia (adhesive resin-composite, Kuraray), Ketac Cem (glass-ionomer, 3M-ESPE), and RelyX-Unicem (3M-ESPE). Specimens were stored in water for 2 weeks, artificially aged by thermal cycling for 1500 cycles, 5-55C, with 45s dwell times; stained with 50% silver nitrate, sectioned MD and B-P; and stain ingress measured using a toolmakers microscope and digital travelling micrometers.
Results: 3-way ANOVA found that the simple main effects of material, cement, and tooth substrate were all large and statistically significant (p<0.001). Cement type had the most important effect. All interaction terms were significant (p<0.05), indicating that different inlay, cement, and tooth substrate combinations behaved differently. Gold and e.max; Ketac Cem and Panavia; and enamel all leaked less than their alternatives (p<0.05).
Conclusions: Inlay material type; cement type; and tooth substrate, enamel or dentin, all profoundly influenced microleakage of indirect inlays. Cement type was most influential.