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We present Spitzer/IRS spectra of 31 TTS and IRAM/1.3mm observations for 34low- and intermediate-mass stars in the Cep OB2 region. Including ourpreviously published data, we analyze 56 TTS and the 3 intermediate-mass starswith silicate features in Tr 37 (~4 Myr) and NGC 7160 (~12 Myr). The silicateemission features are well reproduced with a mixture of amorphous (witholivine, forsterite, and silica stoichiometry) and crystalline grains(forsterite, enstatite). We explore grain size and disk structure usingradiative transfer disk models, finding that most objects have sufferedsubstantial evolution (grain growth, settling). About half of the disks showinside-out evolution, with either dust-cleared inner holes or aradially-dependent dust distribution, typically with larger grains and moresettling in the innermost disk. The typical strong silicate features requirenevertheless the presence of small dust grains, and could be explained bydifferential settling according to grain size, anomalous dust distributions,and/or optically thin dust populations within disk gaps. M-type stars tend tohave weaker silicate emission and steeper SEDs than K-type objects. Theinferred low dust masses are in a strong contrast with the relatively high gasaccretion rates, suggesting global grain growth and/or an anomalous gas to dustratio. Transition disks (TD) in the Cep OB2 region display strongly processedgrains, suggesting that they are dominated by dust evolution and settling.Finally, the presence of rare but remarkable disks with strong accretion at oldages reveals that some very massive disks may still survive to grain growth,gravitational instabilities, and planet formation.

Dust properties and disk structure of evolved protoplanetary disks in Cep OB2: Grain growth, settling, gas and dust mass, and inside-out evolution