In each of 40 patients , one single-rooted tooth was extracted and four treatment modalities were randomly assigned to the following groups ( n = 10 each ) : A ) - tricalcium-phosphate-particles with a polylactid coating ( - TCP ) , B ) demineralized bovine bone mineral with 10 % collagen covered with a collagen matrix ( DBBM-C/CM ) , C ) DBBM with 10 % collagen covered with an autogenous soft tissue punch graft ( DBBM-C/PG ) , D ) spontaneous healing ( control ) .