Histological evaluation of peri-implant soft tissues in immediately loaded implants featuring different implant-abutment connections: A preliminary study

The aim of the present study is to evaluate the peri-implant soft tissues and the amount of inflammatory cells around two different implant-abutment connections (self-locking conical connection with platform switching and screwed connection with standard abutment and internal anti-rotational system). Histological analysis was made of 14 implants, 7 with self-locking Morse tapered connection (experimental group A) and 7 with screw-retained anti-rotational connection (control group B). Sixty days after non-functional immediate loading, peri-implant tissue biopsies were performed. In the samples taken from the experimental group the peri-implant connective tissue consisted of a greater density of collagen and fibroblasts compared to the connective tissue of the control group. The experimental group specimens showed less inflammatory infiltrate close to the self-locking tapered connection compared to the tissues around the screw-retained connection. The SEM observations showed less microgap in the self-locking conical connection than in the screw connections with standard abutment and internal anti-rotational system. The presence of connective tissue with few inflammatory cells and the absence of inflammatory infiltrate, in self-locking conical connection implants is due to the minimal size of the implant-abutment microgap that does not allow the passage of fluids and bacteria from the oral cavity to the implant thus preventing tissue inflammation.