The Potential Risk of Conical Implant‐Abutment Connections: The Antirotational Ability of <scp>C</scp>owell Implant System

Yao, Kuang Ta; Kao, Hung Chan; Cheng, Cheng‐Kung; Fang, Hsu Wei; Huang, Chang Hung; Hsu, Ming Lun

doi:10.1111/cid.12219

Cited by 19 publications

(23 citation statements)

References 21 publications

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“…Hence, Gr NS(I) could pass the cyclic test in the current study, but Gr NS(NI) could not. The surface analysis of the abutments through SEM indicated burnishing on the octagonal corners, revealing that the index could provide resistance to the torsional moment, similar to the findings of Katsuta and Watanabe (), Sakamoto et al (), and Yao et al (, ). Therefore, the index design is crucial for achieving stable connections because it provides antitorsion (Khraisat, Hashimoto, Nomura, & Miyakawa, ; Yao et al, ).…”

Section: Discussionsupporting

confidence: 83%

“…Furthermore, the more frictional resistance from this stage could improve the antitorsional ability of the conical connection. In our previous study regarding the antitorsional ability of the conical connection, purely conical abutments did not pass the cyclic test, resulting in abutment rotation with few cycles (<150 cycles) under the bending and torsional moments (Yao et al, ). By contrast, in this study, on the condition of adding a more axial loading, the same purely conical abutments of Gr S(NI), a control group, all passed the cyclic test (with >10 6 cycles).…”

Section: Discussionmentioning

confidence: 98%

“…Here, the loading condition (200 N and 30° off‐axis to implant axis) was based on posterior occlusion during normal human chewing; in other words, in this condition, the peak load is 200 N on a molar crown with 30° cuspal inclination (Khraisat, Stegaroiu, Nomura, & Miyakawa, ), and it generates bending and torsional moments and axial loading on the specimen. Of these, the bending and torsional moments on the implant system can be viewed as unfavorable factors separating or loosening abutments from an implant–abutment connection (Khraisat, Abu‐Hammad, Dar‐Odeh, & Al‐Kayed, ;Yao et al, ). Regarding the mechanical properties, the conical implant–abutment connection systems have excellent antibending ability (Coppede et al, ), which could be attributed to the wedging effect and large‐area intimate contact between conical abutments and implants.…”

Section: Discussionmentioning

confidence: 99%

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Abutment screw withdrawal after conical abutment settlement: A pilot study

Yao

Chang

Fang

et al. 2019

Clinical Oral Implants Res

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Objective This study investigated the effects of abutment screw withdrawal after conical abutment settlement on the stability of the implant–abutment connection. Materials and methods Twenty implants of a conical connection system were used. Two two‐piece abutment designs were used: cone only (n = 10; NI) and cone plus octagonal index design (n = 10; I); for each design, five samples were used with (S) and without (NS) abutment screw withdrawal before a cyclic test. Finally, four groups, namely Gr S(NI), Gr S(I), Gr NS(NI), and Gr NS(I), were included. The cyclic test included cyclic loading of 20–200 N, 30°, and 4‐mm off‐axis to implant axis at 10 Hz for 106 cycles, simulating a clinical time interval of 40 months. The fatigue cycles were recorded. The axial displacement of the conical abutments during abutment settlement, screw withdrawal, and cyclic loading were measured. Abutment morphology was examined through scanning electron microscopy (SEM). Results Only Gr NS(NI) failed the test, indicating that without the index design and abutment screw withdrawal, and connection stability seriously deteriorated. Gr NS(I) exhibited significantly higher axial displacement into the implant after abutment settlement than did Gr NS(NI). It also exhibited continuous axial displacement into the implant after cyclic loading. SEM after cyclic testing in Gr NS(I) revealed marked burnishing on lateral edges of the index, indicating that the index design provides an antitorsional ability. Conclusion Although this study has few limitations, abutment screw withdrawal is feasible in this conical implant–abutment connection system with index design.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

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Abutment screw withdrawal after conical abutment settlement: A pilot study

Yao

Chang

Fang

et al. 2019

Clinical Oral Implants Res

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“…The anti‐rotation design of the abutment can limit the rotational freedom, thereby maintaining well the stability of the joint. In the experiment of Yao et al, all the abutments without anti‐rotation design were rotated after cyclic loading, and fatigue fracture was observed. In addition, the anti‐rotation design can also effectively reduce the incidence of abutment screw loosening by increasing the preload .…”

Section: The Factors Contributed To Abutment Screw Looseningmentioning

confidence: 99%

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

Huang

Wang

2019

J Esthet Restor Dent

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Objective While the loosening of the abutment screw is one of the most common complications in implant‐supported restorations, there is a lack of comprehensive literatures for mechanism of and factors associated with the loosening of the implant abutment screw. The review was to summarize the mechanism of and factors associated with the loosening of the implant abutment screw. Overview A total of 99 relevant articles were included in the literature review. The mechanism of the abutment screw loosening was explained. The factors contributed to abutment screw loosening were divided into five aspects and then expounded respectively. Conclusions The internal connection and abutments with anti‐rotational and conical designs have better resistance to screw loosening. Cantilevers increase the risk of screw loosening. The effect of surface treatment of the abutment screw is unsure. Clinicians need to tighten the abutment screw to the recommended torque while avoiding repeated tightening and loosening, and increase the frequency of follow‐ups to retighten the loosened screws in time. Clinical Significance While the loosening of the abutment screw is one of the most common complications in implant‐supported restorations, there is a lack of comprehensive literatures for mechanism of and factors associated with the loosening of the implant abutment screw. The review was to summarize the mechanism of and factors associated with the loosening of the implant abutment screw, so that clinicians may make better choices in clinical practice.

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“…In a true conical connection, the fit relates to the taper degree and connection area. The anti-torsional ability is dependent on the frictional resistance in the cone being greater than the torsion movement (Yao et al, 2015;Yao et al, 2019). Given high occlusal forces, this is often difficult to maintain clinically, so a hybrid connection is often designed to incorporate self-locking mechanisms that can mitigate abutment rotation and micromovements that can compromise restorative success.…”

Section: Introductionmentioning

confidence: 99%

In vitro assessment of connection strength and stability of internal implant-abutment connections

Kofron

Carstens

Cong

et al. 2019

Clinical Biomechanics

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Background: Various connections have been machined to improve the fit between the dental abutment and implant. In vivo, the instability created by imprecisely fitting components can cause soft tissue irritation and bacterial colonization of the implant system. The aim of this study was to quantify abutment stability under in vitro force applications. Methods: Abutment stability and fit were quantitatively measured after application of rotational, vertical, and horizontal forces. Findings: The abutment connection held by friction (Friction-Fit) was the only group to have 0°angular rotation. A significantly greater vertical force was required to pull the abutment from the implant for the Friction-Fit connection as compared to all other experimental groups. The abutment connection held by a mechanically locking friction-fit with four grooves (CrossFit) and Friction-Fit demonstrated significantly lower lateral movement as compared to all other connections. The remaining connections evaluated included two hexagon connections that rely on screw placement for abutment fit (Conical + Hex #1 and Conical + Hex #2), one connection with protruding slots to align with recessed channels inside the implant (Conical + 6 Indexing Slots), and an internal connection that allows for abutment indexing every 120°(Internal Tri-Channel). Interpretation: Internal connection geometry influenced the degree of abutment movement. Friction-Fit and CrossFit connections exhibited the lowest rotational and horizontal motions. Significant differences were found between Friction-Fit and CrossFit following the application of a vertical force, with the Friction-Fit requiring a significantly greater pull force to separate the abutment from the implant.

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The Potential Risk of Conical Implant‐Abutment Connections: The Antirotational Ability of Cowell Implant System

Abstract: In Cowell implant system (taper angle = 7°), there was no antirotational ability in purely conical connections. Adding an octagonal index could provide an antirotational function but could compromise the antibending strength of the abutment.

Cited by 19 publications

References 21 publications

Abutment screw withdrawal after conical abutment settlement: A pilot study

Abutment screw withdrawal after conical abutment settlement: A pilot study

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

In vitro assessment of connection strength and stability of internal implant-abutment connections

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