Int J Oral Maxillofac Implants 28 (2013), No. 2 15. Mar. 2013
Int J Oral Maxillofac Implants 28 (2013), No. 2 (15.03.2013)
Page 494-502, doi:10.11607/jomi.3081, PubMed:23527352
Soft and Hard Tissue Histologic Dimensions Around Dental Implants in the Canine Restored with Smaller-Diameter Abutments: A Paradigm Shift in Peri-implant Biology
Cochran, David L. / Mau, Lian Ping / Higginbottom, Frank L. / Wilson, Thomas G. / Bosshardt, Dieter D. / Schoolfield, John / Jones, Archie A.
Purpose: To evaluate the biologic width dimensions around implants with nonmatching implant-abutment diameters.
Materials and Methods: Five canines had their mandibular premolars and first molars removed bilaterally and replaced with 12 implants that had nonmatching implant-abutment diameters. On one side, six implants were placed in a submerged surgical approach, and the other side utilized a nonsubmerged approach. Two of the implants on each side were placed either 1 mm above, even with, or 1 mm below the alveolar crest. Two months later, gold crowns were attached, and the dogs were sacrificed 6 months postloading. Block sections were processed for histologic and histomorphometric analyses.
Results: The bone level, connective tissue length, epithelial dimension, and biologic width were not significantly different when the implants were initially placed in a submerged or nonsubmerged surgical approach. The bone level was significantly different around implants placed 1 mm above the crest compared to implants placed even with or 1 mm below the alveolar crest. The connective tissue dimension was not different for any implant level placement. The epithelial dimension and biologic width were significantly greater for implants placed 1 mm below the alveolar crest compared to implants placed even with or 1 mm above the alveolar crest. For five of six implant placements, connective tissue covered the implant/abutment interface.
Conclusions: This study reveals a fundamental change in the biologic response to implants with nonmatching implant-abutment diameters. Unlike implants with matching implant-abutment diameters, the connective tissue extended coronally past the interface (microgap). This morphologic tissue alteration represents a significant change in the biologic reaction to implant-abutment interfaces and suggests that marginal inflammation is eliminated or greatly reduced in these implant designs.