A 16–year Study of the Microgap Between 272 Human Titanium Implants and Their Abutments
A microgap has been described at the level of the implant-abutment connection. This microgap can be colonized by bacteria, and this fact could have relevance on the remodeling of the peri-implant crestal bone and on the long-term health of the peri-implant tissues. The authors report on 272 implants with screw- or cement-retained abutments retrieved from humans for different causes during a 16-year period. In the implants with screw-retained abutments, a 60-μm microgap was present at the level of implant-abutment connection. In some areas the titanium had sheared off from the surface and from the internal threads. The contact between the threads of the implant and those of the abutment was limited to a few areas. Bacteria were often present in the microgaps between implant and abutment and in the internal portion of the implants. In implants with cement-retained abutments, a 40-μm microgap was found at the level of the implant-abutment connection. No mechanical damage was observed at the level of the implant or of the abutment. All the internal voids were always completely filled by the cement. No bacteria were observed in the internal portion of the implants or at the level of the microgap. The differences in the size of the microgap between the two groups were statistically significant (P < .05). In conclusion, in screw-retained abutments the microgap can be a critical factor for colonization of bacteria, whereas in cement-retained abutments all the internal spaces were filled by cement. In these retrieved implants, the size of the microgap was markedly variable and much larger than that observed in vitro.Abstract


Contributor Notes
Antonio Scarano, DDS, MD, is a researcher, Giovanna Iezzi, DDS, is a research fellow, Maurizio Piattelli , MD, DDS, is an associate professor, and Adriano Piattelli, MD, DDS, is professor of Oral Medicine and Pathology, Dental School, University of Chieti-Pescara, Chieti, Italy. Address correspondence to Prof Piattelli at Via F Sciucchi 63, 66100 Chieti, Italy (apiattelli@unich.it).
Bartolomeo Assenza, MD, DDS, is a visiting professor at Dental School, University of Chieti-Pescara, Chieti, Italy, and is in private practice in Cologno Monzese (MI), Italy.
Giulio C. Leghissa, MD, DDS, is in private practice in Milano, Italy.
Alessandro Quaranta, DDS, is a research fellow at Dental School, University of Rome “La Sapienza,” Rome, Italy.
Pietro Tortora, MD, DDS, is with the Department of Oral and Maxillofacial Surgery at Cardarelli General Hospital, Naples, Italy.