Reason for loosening of ceramic restorations -

The resin cement forms the weakest link for a ceramic restoration. This was found in an investigation of the de-bonding of resin cementation of zirconia or lithium di-silicate ceramic to bovine dentin.

Peroxide-free tooth whitening -

The peroxide-free tooth whitening products are less effective than those based on peroxides and the effect is only transitory. Both peroxide-free and peroxide containing products gave an initial lightening of the tooth color. However, the effects of peroxide-free products were only transitory.