This study was developed for evaluating the possible causes of losing primary stability of dental implants and to find possible associations between implant designs or implant surface treatment and the quality of surrounding bone tissue. There have been evaluated five CP (Commercial Products) titanium dental implants having different shapes and surface morphology. All the implants have been extracted between three and six month from insertion time due to the loosening of primary stability. The lost during three to six months of the primary stability for the dental implants evaluated at the interface was attributed to blood supply deficiency of the surrounding bone in case of the implants inserted in the anterior-lateral and lateral mandible bone, on implant surrounding bone with consecutive necrosis without leaving the possibility of normal healing both for the maxilla and the mandible, or to prosthetic load deficiency by applying forces out of the implant axis.