A modified oxidic or silicate filler, comprising:

• at least one oxidic or silicate filler modified with a mercaptosilane of formula (I):

  (R¹)₃Si—R²—SHI,

• wherein the R¹ substituents are identical or different and consist of alkoxy or alkyl, with at least one R¹ group being an alkoxy group, and R² is a divalent hydrocarbon group, or modified with an alkylsilane of formula (II):

  (R¹)₃Si—R³ II,

• wherein R¹ is as defined above and R³ represents a saturated or unsaturated, branched or unbranched alkyl radical, and/or modified with silicone oil.