Stability of external and internal implant connections after a fatigue test

Abstract

Objective:The objective of this study was to compare the torque and detorque values of screw intermediates of external hexagon, internal hexagon, and Morse taper implants in single restorations before and after mechanical cycling.Materials and Methods:The study sample was divided into three groups (n = 10) as follows: group EH – external hexagon implant, group IH – internal hexagon implant, and group MT – Morse taper implant. Universal abutments were screwed on the implants, and metal crowns were cemented onto the abutment. The samples were submitted to a mechanical testing of 1 million cycles, with a frequency of 8 cycles per second under a 400 N load. The application and registration of the screw torque (T0) and detorque (T1) values of the intermediate were performed before and after the test. The results were statistically evaluated by analysis of variance (ANOVA) and Tukey's test (α = 0.05).Results:There was no difference between the values of T0 and T1 in the intra-group samples. However, the inter-group difference in T0 between the EH (12.8 N cm) and MT (18.6 N cm) groups and in T1 between the EH (10.4 N cm) and IH (13.8 N cm), EH and MT (19.4 N cm), and MT and IH (P = 0.001) groups were significant. The MT group showed a lower variation of T0 and T1.Conclusion:The internal implants, particularly MT, showed better stability in these cases when used for single restorations.

A Current Perspective on Screw‐Retained Single‐Implant Restorations: A Review of Pertinent Literature

“…14 Internalconnection implants were then developed to mitigate screw loosening and have demonstrated greater retention and stability for single-tooth implant restorations. 15 Feitosa and colleagues 16 and Gracis and colleagues 17 both reported greater stability and less screw loosening with internal-connection implants. Theoharidou and colleagues 18 found screw loosening of both internal and external implant connections to be a rare event in single-tooth restorations.…”

Mechanism of and factors associated with the loosening of the implant abutment screw: A review

“…Among these, the loosening of the abutment screw is one of the most common mechanical complications . The incidence rate of abutment screw loosening reaches 5.3% in the first year after loading, and 5.8%‐12.7% after the 5‐year follow‐up . The loosening of the abutment screw is likely to deteriorate into fracture of the screw or even fracture of the implant without timely management.…”

“…11,13,14 The incidence rate of abutment screw loosening reaches 5.3% in the first year after loading, 15 and 5.8%-12.7% after the 5-year follow-up. 14,[16][17][18] The loosening of the abutment screw is likely to deteriorate into fracture of the screw or even fracture of the implant without timely management. The instability of the prosthesis, which is caused by the loosening of the abutment screw, changes the distribution of the occlusal force during function, thus accelerating the progress of the abutment screw loosening.…”

Pérdida de torque de los tornillos de fijación del pilar en implantes sometidos a cargas cíclicas

“…Debido al pequeño tamaño muestral (n=30), se resaltaron como importantes algunas observaciones que no alcanzaron el grado de significancia estadística establecido en p-valor 0.05, dado que, con una alta probabilidad, una ampliación del tamaño muestral habría declarado dicha discrepancia como estadísticamente significativa. No obstante, algunos estudios han utilizado tamaños muestrales similares, como Dixon et al (n=30; n subgrupo=5) 54 , Park et al 33 (n=30 sin subgrupos) y Feitosa et al 89 (n=30 sin subgrupos), 90 e incluso más pequeños, como en los estudios de Steinebrunner et al 91 , Junqueira et al 34 , Marchetti et al 25 y Farina et al 90 (n=6, n=10, n=15 y n=20 respectivamente). No obstante también existen estudios con tamaños muestrales superiores al nuestro como el de Shin et al 92 (n=35; n subgrupo=5), Siamos et al 57 (n=40; n subgrupo= 10), Piermatti et al 46 (n=40), Ricciardi et al 93 (n=44), Butignon et al 41 (n=45; n subgrupo= 15), Kim et al 74 (n=50; n subgrupo=10), Ha et al 75 (n=60), Delben et al 61 (n=60), Tsuge y Hagiwara 55 (n=64; n subgrupo=16), Murmura et al 60 (n=70; n subgrupo=23) y Freitas et al 23 (n=84).…”

“…Los estudios con metodología comparable al presente trabajo 25,33,34,46,55,56,60,61,72,74,75,89,90,91,92,93 emplean, en general, números de ciclos masticatorios simulados iguales o superiores a 10 6 , siguiendo algunos de ellos la norma ISO 14801 12 llegando a los 5 x 10 6 ciclos de masticación simulada que equivaldrían a 6 años de utilización de la implanto-prótesis 25 , como son los trabajos de Junqueira et al 34 y Marchetti et al 25 . Algunos de los estudios revisados presentan el mismo número de ciclos que en el presente estudio, como Freitas et al 23 o Butignon et al 41 El peso empleado en el este estudio fue de 90 N (9 kg), este valor se halla dentro del rango de carga empleada por los estudios precedentes que van desde los 4.45 N del estudio de Siamos et al 57 a los 400 N empleados por Feitosa et al 89 (Ver Anexo I, Tabla 25). Los valores normales de fuerza masticatoria en la región molar son de 216 N a 880 N 24, 25 , en la región premolar de 453 N y en la región incisal de entre 108 N y 299 N 23, 25 para la dentición natural.…”