Analysis of Changes in Implant Screws Subject to Occlusal Loading: A Preliminary Analysis

Yousef, Hoda; Luke, Allyn; Ricci, Jack; Weiner, Saul

doi:10.1097/01.id.0000187902.68436.e4

Cited by 47 publications

(50 citation statements)

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“…Approximately 90% of the applied torque is lost as friction. 20 Depending on the manufacturer and the system, recommended abutment screw torque varies from 15 Ncm to 45 Ncm. 21 Even experienced clinicians have been shown to under-tighten abutment screws by 30-50%.…”

Section: Discussionmentioning

confidence: 99%

Retrieval of a fractured abutment screw thread from an implant: a case report

Satterthwaite

Rickman

2008

Br Dent J

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Section: Discussionmentioning

confidence: 99%

Retrieval of a fractured abutment screw thread from an implant: a case report

Satterthwaite

Rickman

2008

Br Dent J

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“…On the other hand, the preload values should not be too low in order to retain loose screws under repeated functional forces 16 . Eccentric and compressive forces are generated during chewing movements and influence the screw retention 3,8,[17][18][19][20] . The optimal preload values for the implant/abutment screw joint have not been fully identified and in single tooth implants this value is critical for screw joint stability 21 .…”

Section: Introductionmentioning

confidence: 99%

Screw loosening of different UCLA-type abutments after mechanical cycling

Junqueira¹,

Ribeiro²,

Faria³

et al. 2013

Braz. J. Oral Sci.

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Aim: To evaluate the loss of applied torque (detorque) values in cast and pre-machined abutments for external hex abutment/implant interface of single implant-supported prostheses subjected to mechanical cycling. Methods: Ten metal crowns were fabricated using two types of UCLA abutments: cast and pre-machined with metal base in NiCrTi alloy and tightened to regular external hex implants with a titanium alloy screw, with an insertion torque of 32 N.cm, measured with a digital torque gauge. Samples were embedded with autopolymerizing acrylic resin in a stainless steel cylindrical matrix, and positioned in an electromechanical machine. Dynamic oblique loading of 120 N was applied during 5 x 10 5 cycles. Then, each sample was removed from the resin and detorque values were measured using the same digital torque gauge. The difference of the initial (torque) and final (detorque) measurement was registered and the results were expressed as percentage of initial torque. The results of torque loss were expressed as percentage of the initial torque and subjected to statistical analysis by the Student's t-test (p<0.05) for comparisons between the test groups. Results: Statistical analysis demonstrated that mechanical cycling reduced the torque of abutments without significant difference between cast or pre-machined UCLA abutments (p=0.908). Conclusions: Within the limitations of this in vitro study, it may be concluded that the mechanical cycling, corresponding to one-year use, reduced the torque of the samples regardless if cast or pre-machined UCLA abutments were used.

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“…If the joint is compressed, the preload will be lost, rendering the screw and joint vulnerable to plastic deformation, and the joint may separate. 15 Preload can be influenced by the torque application technique, 2,9 type of the screws used for the prosthesis retention, 13,15 implant/abutment fit, prosthetic cylinder/abutment fit, 10 bending moments, functional loads, 5 framework material, 16 and implant/abutment joint designs. 10 It is important to realize that each implant manufacturer system uses different materials and designs and that the amount of clamping force that is required to keep the joint stable is system specific.…”

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confidence: 99%