Citation: Vinhas, A.S.; Aroso, C.;
Salazar, F.; Relvas, M.; Braga, A.C.;
Ríos-Carrasco, B.; Gil, J.; Rios-Santos,
J.V.; Fernández-Palacín, A.;
Herrero-Climent, M. In Vitro Study of
Preload Loss in Different Implant
Abutment Connection Designs.
Materials 2022, 15, 1392. https://
doi.org/10.3390/ma15041392
Academic Editors:
Alberto Campagnolo and
Alberto Sapora
Received: 10 January 2022
Accepted: 10 February 2022
Published: 14 February 2022
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Article
In Vitro Study of Preload Loss in Different Implant Abutment
Connection Designs
Ana Sofia Vinhas
1
, Carlos Aroso
1
, Filomena Salazar
1
, Marta Relvas
1
, Ana Cristina Braga
2
,
Blanca Ríos-Carrasco
3,
* , Javier Gil
4
, José Vicente Rios-Santos
3
, Ana Fernández-Palacín
5
and Mariano Herrero-Climent
6
1
UNIPRO—Oral Pathology and Rehabilitation Research Unit, University Institute of Health Sciences (IUCS),
CESPU, 4585-116 Gandra, Portugal; ana.vinhas@iucs.cespu.pt (A.S.V.); carlos.ribeiro@iucs.cespu.pt (C.A.);
filomena.salazar@cespu.pt (F.S.); marta.relvas@iucs.cespu.pt (M.R.)
2
Department of Production and Systems Engineering, ALGORITMI Research Centre, Campus Gualtar,
Minho University, 4710-057 Braga, Portugal; acb@dps.uminho.pt
3
Department of Periodontology, School of Dentistry, Universidad de Sevilla, C/Avicena S/N,
41009 Sevilla, Spain; jvrios@us.es
4
Technological Health Research Center, Biomaterials of the Faculties of Medicine and Dentistry,
International University of Cataluña, 08034 Barcelona, Spain; xavier.gil@uic.cat
5
Departamento de Medicina Preventiva y Salud Pública, Facultad de Medicina de Sevilla, 41009 Sevilla, Spain;
afp@us.es
6
Porto Dental Institute, 4150-518 Porto, Portugal; dr.herrero@herrerocliment.com
* Correspondence: brios@us.es
Abstract:
The stability and integrity of the abutment-implant connection, by means of a screw, is
fallible from the moment the prosthetic elements are joined and is dependent on the applied preload,
wear of the components and function. One of the main causes of screw loosening is the loss of preload.
The loosening of the screw-abutment can cause complications such as screw fracture, marginal gap,
peri-implantitis, bacterial microleakage, loosening of the crown and discomfort of the patient. It is
also reported that loosening of the screw/abutment may lead to a failure of osseointegration. It is
necessary to evaluate and quantify, with
in vitro
studies, the torque loss before and after loading in
the different connections.
Aim:
evaluate the influence of implant- abutment connection design in
torque maintenance after single tightening, multiple tightening and multiple tightening followed
by mechanical cycling.
Materials and Methods
: 180 Klockner implants divided in 4 groups: 15 SK2
external connection, 25 Ncm tightening torque; 15 KL external connection, 30 Ncm tightening torque;
15 Vega internal connection, 25 Ncm tightening torque; 15 Essential internal connection, 30 Ncm
tightening torque. In each group removal torque values (RTV) were evaluated with a digital torque
meter, in 3 distinct phases: after one single tightening, 10 multiple tightenings and 10 multiple
tightenings and cyclic loading (500 N
×
1000 cycles).
Results:
After one single tightening, and for
all connections, RTV were lower than those of insertion, but only for Essential and Vega internal
connections this result was statistically significant. After multiple tightening, RTV were significantly
lower in all connections. After repeated tightening followed by cyclic loading, mean RTV were
significantly lower, when compared to insertion torque. The multiple tightening technique resulted
in higher RTV than the single tightening technique, except for Vega implant. The multiple tightening
followed by cyclic load, compared to the other phases, was the one that generated the lowest RTV,
for all connections.
Conclusions:
The connection design, in our study, did not seem to influence
the maintenance of preload. Loading influenced the loss of preload, in the sense that significantly
decreased the removal torque values. The multiple re-tightening technique resulted in higher removal
torque values than the single tightening technique. Clinically, our results recommend to retighten
retaining screws, a few minutes after insertion.
Keywords:
implant abutment connections; preload loss; tightening torque; retightening; cyclic
loading
Materials 2022, 15, 1392. https://doi.org/10.3390/ma15041392 https://www.mdpi.com/journal/materials
