Magister Chirurgiae Dentium (MChD) / Background: Lack of appropriate bone thickness is a common clinical limitation for tooth replacement, often requiring narrow implants, which have shown better results when combined with Morse taper connections. Little is known about the sealing of the abutment-implant interface of narrow implants with Morse taper connections against oral bacteria. Aims: To investigate the in vitro ability of four commercially available narrow diameter implant (< 3.5 mm) with Morse-taper type implant abutment connections to impede bacterial penetration of their implant abutment interface (IAI). Material and Methods: Four commercially available narrow implant systems with Morse taper connections were subjected to Streptococcus sanguinis cultures in vitro and evaluated for contamination and microgaps through Scanning Electron Microscopy (SEM). Results: Bacterial penetration of the IAI was observed in all systems (n=12), ranging from 65 to >300 CFU. There were no statistically significant differences in the average log CFU between the four implant groups (χ2= 5.244, P=0.155). Microgaps ranging from 5-10 μm were observed in all assemblies when analyzed under SEM, with no statistically significant differences between the different systems (P>0.05). Conclusions: Despite the advantages of Morse taper systems, the evaluated narrow diameter implants using this type of abutment geometry failed to provide bacterial sealing. The observed microgaps can form reservoirs and potentially lead to inflammation in the peri-implant tissues and micromovements.

Magister Scientiae Dentium - MSc(Dent) / Lack of appropriate bone thickness is a common clinical limitation for tooth replacement, often requiring narrow implants, which have shown better results when combined with Morse taper connections. Little is known about the sealing of the abutment-implant interface of narrow implants with Morse taper connections against oral bacteria.