Composite resin materials for posterior restorations are becoming more and more popular. According to the market, Ormocer materials are more expensive than composite resin this paper is comparing the resistance to fracture between nanohybrid composites and Ormocers under vertical forces to evaluate their cost efficiency in the dental cabinets. 20 teeth were prepared and filled with Ormocer and 20 with nanohybrid composite respectively. All the samples were sent for measuring under vertical pressure with the use of a universal testing machine. The average value of fracture for Ormocer was slightly higher (1541 N) than the average value of fracture of the nanohybrid composite (1431 N). Considering the similarity in the average values of the two materials we should look into the other properties (biocompatibility, shrinkage, aesthetics, etc) to take a final decision. Both materials can be used with the same rate of success taking in account always the protocol provided by the manufacturer.

Implants have been around for many years already, having a lot of advantages and high success rates, by some authors even higher than 90%. Nevertheless, throughout the years, problems and failures have occurred in practice which led to bone loss around the implants and even, in some cases, to losing the implant itself. The phenomenon behind this pathological process -peri-implantitis - is believed to be the microleakage which occurs at the implant-abutment interface.This happens due to the existence of a gap present between the implant and the prosthetic abutment. Moreover, the microleakage is amplified because of the, so called, pumo effect. The pump effect occurs when the crown-abutment complex is subjected to occlusal, vertical and oblique, forces. During these micro-movements of the abutment, the microleakage intensifies and the bacteria can easily enter inside the implant, where is impossible to reach and remove through oral hygiene, thus, creating the perfect conditions for peri-implantitis. There are two major types of implant-abutment connections widely used nowadays -internal hex and conical -which are believed to influence the phenomenon and, so, the outcome. In the present study, both types of connections are tested, using Streptococcus Mutans, a common bacteria found in the oral cavity.