In which of the following situations composites should be avoided:
Fissure sealant
Root surface lesion
Preventive resin restoration
Posterior teeth restorations
Composites are usually contraindicated in root surface lesions as gap formation is seen as a result of the forces of polymerization shrinkage being higher than initial bond strength.  
Composites are effectively used for pit and fissure sealants, preventive resin restorations and core build ups.