[en] Mandibular overdentures retained by two implants are recognised as the first option for treating patients without teeth, as stated by the McGill University (Canada) in its consensus statement in 2002 and the British Society to the prosthodontics study, in your consensus statement of York, published in 2009. Compared to conventional full prosthesis, they provide greater satisfaction for the patient, greater chewing ability and preservation of the residual crest height. Purpose: This in vitro study was investigated and compare the durability and retention capacity of 3 types of attachments. Our working hypothesis states that there is no significant retention loss in different systems "attachments" tested and used in implant supported overdentures over the time and no wear in the metal components that's requiring replacement during the same period. Materials and Methods: Three commercially available attachments were investigated:(Clix®: Preat Corporation, Santa Ynez, CA, United States; Dalbo-Plus®: Cendres+ Métaux, Biel/Bienne, Switzerland; Locator®: Zest Anchors,Inc ,Escondido, United States), 3 different abutments inclinations (0°, 10° and 20°) . The 72 attachments were placed in acrylic resin form and they were then subjected to mechanical testing (5400 cycles of insertion and removal) over the respective ball or Locator abutments immersed in artificial saliva at pH7 and 37°C, and retention values recorded at eight different times (at the beginning, one month, six months, a year, two years, three years, four years and five years). Results: The results revealed that there were significant differences in the average values of insertion/removal force due to the angulation (F (2, 48) =343619, p<0.05) and the type of attachment (F (7, 48) = 23.220, p < 0.05). An analysis of the results showed that the retention average (insertion and removal) for attachments was always more in inclination of 0° than inclination of 20°. Conclusions: All attachments were tested lose the maximum value of retention force. The abutment inclination influences the intrinsic strength value of each attachment and have effect on its durability over the period of time.

[es] Las sobredentaduras mandibulares retenidas por dos implantes son reconocidas como la primera opción de tratamiento para pacientes edéntulos, tal como recoge la Universidad McGill (Canadá) en su declaración de consenso publicada en 2002 y la sociedad británica para el estudio de la odontología protésica, en su declaración de consenso de York, publicada en 2009. Al compararlas con prótesis completas convencionales, proporcionan una mayor satisfacción del paciente, una mayor capacidad masticatoria y una preservación de altura de la cresta residual. El objetivo de este trabajo es evaluar la durabilidad y capacidad de retención de attachments a largo del tiempo en inclinación de 0°, 10° e 20° y en saliva artificial a 37°C.El diseño experimental tomó en cuenta la existencia de 3 tipos distintos de sistemas de attachments (Clix®: Preat Corporation, Santa Ynez, CA, United States; Dalbo-Plus®: Cendres+ Métaux, Biel/Bienne, Suiza; Locator®: Zest Anchors,Inc ,Escondido, United States), 3 inclinaciones diferentes y uno tipo de saliva artificial ( pH 7). Los 72 attachments fueron testados en una máquina de ensayo de fatiga durante 5400 ciclos (cinco años) y se registraron los valores de retención en ocho momentos diferentes (inicio, un mes, seis meses, un año, dos años, tres años, cuatro años, cinco años).El análisis de los resultados demostró que la media de retención (inserción y desinserción) de los attachments fue siempre mayor en inclinación de 0° do que en inclinación de 20°. Todos los attachments del estudio han perdido valor máximo de retención.La inclinación influye en el valor de la fuerza intrínseca de cada attachment y tiene influencia en su durabilidad a lo largo del tiempo.