Relation between implant/abutment vertical misfit and torque loss of abutment screws

Barbosa, Gustavo Augusto Seabra; Bernardes, Sérgio Rocha; Neves, Flávio Domingues das; Neto, Alfredo Júlio Fernandes; Mattos, Maria da Glória Chiarello de; Ribeiro, Ricardo Faria

doi:10.1590/s0103-64402008000400013

Cited by 49 publications

(44 citation statements)

References 10 publications

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“…This is in agreement with other studies (6,17). Perfectly fitting multi-unit implant dentures have been a theoretical ideal, but hardly achievable clinically.…”

Section: Discussionsupporting

confidence: 93%

Effect of retorque on loosening torque of prosthetic screws under two levels of fit of implant-supported dentures

et al. 2010

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This study evaluated the influence of retorque on loosening torque (Lt) of prosthetic screws in implant-supported dentures with different fit levels. Ten mandibular implant-supported dentures were fabricated and then 20 cast models were then prepared using prosthetic structures to create 2 fit levels: passive fit (Pf) and misfit (Mf). Two tightening techniques were also evaluated: initial torque only (T1); and initial torque and retorque after 10 min (T2). Gold or titanium screws were used, resulting in 4 groups to each one: Pf/T1, Pf/T2, Mf/T1, Mf/T2. The Lt was measured 24 h after the tightening torque using digital torque meter. Data were analyzed statistically by two-way ANOVA and Tukey's test (α=0.05), separately for each screw material. For titanium screws, no significant difference (p>0.05) was found between Pf/T1 and Pf/T2, or between Pf/T2 and Mf/T2. However, statistically significant difference (p<0.05) was found between Pf/T1 and Mf/T1, and between Mf/T1 and Mf/T2. Mf reduced the Lt using T1, while and T2 increased the Lt for Mf. Retorque and fit were shown to have no significant influence on the Lt of the gold screws. Retorque application made insignificant the misfit effect on the Lt of the titanium screws, suggesting that this procedure should be performed routinely during the screw tightening in multi-unit dentures.

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“…This is in agreement with other studies (6,17). Perfectly fitting multi-unit implant dentures have been a theoretical ideal, but hardly achievable clinically.…”

Section: Discussionsupporting

confidence: 93%

Effect of retorque on loosening torque of prosthetic screws under two levels of fit of implant-supported dentures

et al. 2010

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“…These findings may be explained by the reduction of the torque values after casting procedures and the presence of roughness and irregularities on the contact surface 2 . The misfit between implant and abutment increases stress on the screw and results in metal fatigue failure and screw loosening [10][11] . Even the smallest misfit could result in changes in screw geometry and cause incidence of strain on the screws 12 .…”

Section: Discussionmentioning

confidence: 99%

Failure of prosthetic screws on 971 implants

Morsch¹,

Rafael²,

Dumes³

et al. 2015

Braz. J. Oral Sci.

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Aim: To evaluate the presence of failures in prosthetic screws and whether these failures are related to the type of prosthesis, abutment angulation and presence or not of intermediate. Methods:Two-hundred and sixty-seven patients were evaluated at the Federal University of Santa Catarina, totaling 971 external hexagonal implants in place for at least one year. A Tobit regression model for censored variables was used and the explanatory variables were subjected to percentage analysis. Results: The results demonstrated a relationship between the failure in prosthetic screws and the investigated factors with a significance of F=0.003 and p<0.05. The percentage analysis showed that the prosthetic screw failed in 8.82% of 238 unitary prostheses and 10.1% of 773 multiple prostheses. Among 912 abutments, 9.43% failed and in the 59 angled abutments, failures appeared in 15.25%. A total of 200 prostheses were placed over the implant platform and 13% failed. A total of 771 prostheses were made over abutment and 8.95% of these screws failed. Conclusions: Through multiple linear regression it could be concluded that the type of prosthesis showed no significant influence on the prosthetic screw failure, but other variables were related to this mechanical failure. There was a significant relationship among the variables, demonstrating the need for greater attention in choosing the type of prosthesis, the abutment angulation and whether the prosthesis will be placed directly on the implant platform or on the abutment.

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“…[1345] The most frequently observed complication of screwed and cemented prostheses is loosening of the screw that leads to a misfit of the abutment to the implant after the prosthesis is in use. [13456] The combination of horizontal and vertical misfits may result in a gap leading to an increased area of bacterial accumulation, which complicates clean-up[78] and causes gingival inflammation due to the development of microflora in the gap region. Peri-implantitis and subsequent risks of bone resorption as well as posterior fracture of the screw can develop.…”

Section: Introductionmentioning

confidence: 99%

Stability of external and internal implant connections after a fatigue test

et al. 2013

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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.

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Relation between implant/abutment vertical misfit and torque loss of abutment screws

Cited by 49 publications

References 10 publications

Effect of retorque on loosening torque of prosthetic screws under two levels of fit of implant-supported dentures

Effect of retorque on loosening torque of prosthetic screws under two levels of fit of implant-supported dentures

Failure of prosthetic screws on 971 implants

Stability of external and internal implant connections after a fatigue test

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