Influence of diamondlike carbon-coated screws on the implant-abutment interface.
OBJECTIVE
To evaluate the implant-abutment interface area and the abutment screw loosening value when diamondlike carbon (DLC)-coated or titanium screws were used before and after cyclic loading.


METHODS
Thirty-six implants were divided into four groups according to the type of connection (external hexagon [EH] or internal hexagon [IH]) and the type of abutment screw (with [EHD/IHD] or without [EHT/IHT] DLC coating). The implants were placed in epoxy resin-glass fiber composite, and crowns cast in a metal alloy were screwed to the implants. The implant-abutment interface was measured before (VG1) and after (VG2) cyclic loading. The removal torque values were recorded.


RESULTS
In groups with titanium screws, there was an increase in the implant-abutment interface area from VG1 to VG2, whereas in groups with DLC-coated screws, the interface area was reduced (EHT = 4.49%, IHT = 24.32%, EHD = -1.05%, IHD = -9.95%). In the IHT group only, the implant-abutment interface area showed a statistically significant difference between VG1 and VG2. The Pearson correlation indicated no significant differences among the studied factors, where r = -0.11 for EHT, 0.14 for EHD, 0.07 for IHT, and 0.43 for IHD.


CONCLUSIONS
The implant-abutment interface areas in groups with an EH connection were larger than those in groups with an IH connection, regardless of the type of screws used. The screw loosening values decreased in all groups after cyclic loading. No correlation between the implant-abutment interface area and the screw loosening value was seen.
Department of Prosthodontics, University of Taubate, Taubate, São Paulo, Brazil.
Juliana Socas Vanoni
JS
Diez
Vinicius Carvalho
VC
Brigagão
Leonardo  Gonçalves
L
Cunha
Ana Christina Claro
AC
Neves
Laís Regiane
LR
da Silva-Concilio
D002244:Carbon; D003442:Crowns; D000044:Dental Abutments; D015921:Dental Implants; D018772:Dental Marginal Adaptation; D003772:Dental Pins; D017267:Dental Prosthesis Design; D018130:Diamond; D004853:Epoxy Resins; D006801:Humans; D014025:Titanium; D019415:Torque
D015921:Dental Implants; D004853:Epoxy Resins; D002244:Carbon; D018130:Diamond; D014025:Titanium