Comparison of fit accuracy and torque maintenance of zirconia and titanium abutments for internal tri-channel and external-hex implant connections

PURPOSE: This in vitro study aimed to evaluate the effect of implant connection design (external vs. internal) on the fit discrepancy and torque loss of zirconia and titanium abutments. MATERIALS AND METHODS: Two regular platform dental implants, one with external connection (Brånemark, Nobel Biocare AB) and the other with internal connection (Noble Replace, Nobel Biocare AB), were selected. Seven titanium and seven customized zirconia abutments were used for each connection design. Measurements of geometry, marginal discrepancy, and rotational freedom were done using video measuring machine. To measure the torque loss, each abutment was torqued to 35 Ncm and then opened by means of a digital torque wrench. Data were analyzed with two-way ANOVA and t-test at α=0.05 of significance. RESULTS: There were significant differences in the geometrical measurements and rotational freedom between abutments of two connection groups (P<.001). Also, the results showed significant differences between titanium abutments of internal and external connection implants in terms of rotational freedom (P<.001). Not only customized internal abutments but also customized external abutments did not have the exact geometry of prefabricated abutments (P<.001). However, neither connection type (P=.15) nor abutment material (P=.38) affected torque loss. CONCLUSION: Abutments with internal connection showed less rotational freedom. However, better marginal fit was observed in externally connected abutments. Also, customized abutments with either connection could not duplicate the exact geometry of their corresponding prefabricated abutment. However, neither abutment connection nor material affected torque loss values.

The change of rotational freedom following different insertion torques in three implant systems with implant driver

STATEMENT OF PROBLEM: Implant drivers are getting popular in clinical dentistry. Unlike to implant systems with external hex connection, implant drivers directly engage the implant/abutment interface. The deformation of the implant/abutment interface can be introduced while placing an implant with its implant driver in clinical situations. PURPOSE: This study evaluated the change of rotational freedom between an implant and its abutment after application of different insertion torques. MATERIAL AND METHODS: Three kinds of internal connection implants were utilized for the current study (4.5 x 12 mm Xive, 4.3 x 11.5 mm Inplant Magicgrip, 4.3 x 12 mm Implantium MF). An EstheticBase, a 2-piece top, a Dual abutment was used for its corresponding implant system. The rotational freedom between an implant and its abutment were measured before and after applying 45, 100 Ncm insertion torque. Repeated measures ANOVA was used for statistical analysis. RESULTS: Under 45 Ncm insertion torque, the rotational freedom between an implant and its abutment was significantly increased in Xive (P = .003). However, no significant change was noted in Inplant Magicgrip and Implantium MF. Under 100 Ncm torque, both in Xive (P = .0005) and Implatium MF (P = .03) resulted in significantly increased rotational freedom between the implant and its abutment. DISCUSSION: The design of the implant/implant driver interface effectively prevented the deformation of implant/abutment interface. Little change was noted in the rotational freedom between an implant and its abutment, even though the insertion torque was far beyond clinical application. CONCLUSIONS: The implant/abutment joint of internally connecting implants were quite stable under insertion torque in clinical situation.

Surface change of external hexagon of implant fixture and internal hexagon of abutment after repeated delivery and removal of abutment / 대한치과보철학회지

STATEMENT OF PROBLEM: Repeated delivery and removal of abutment cause some changes such as wear, scratch or defect of hexagonal structure. It may increase the value of rotational freedom(RF) between hexagonal structures. PURPOSE: The purpose of this study was to evaluate surface changes and rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment after repeated delivery and removal under SEM and toolmaker's microscope. MATERIALS AND METHODS: Implant systems used for this study were 3i and Avana. Seven pairs of implant fixture, abutment and abutment screws for each system were selected and all fixtures were perpendicularly mounted in liquid unsaturated polyesther with dental surveyor. Each one was embedded beneath the platform of fixture. Surfaces of hexagonal structure before repeated closing and opening of abutment were observed using SEM and rotational freedom was measured by using toolmaker's microscope. Each abutment was secured to the implant fixture by each abutment screw with recommended torque value using a digital torque controller and was repeatedly delivered and removed by 20 times respectively. After experiment, evaluation for the change of hexagonal structures and measurement of rotational freedom were performed. RESULT: The results were as follows ; 1. Wear of contact area between implant fixture and abutment was considerable in both 3i and Avana system. Scratches and defects were frequently observed at the line-angle of hexagonal structures of implant fixture and abutment. 2. In the SEM view of the external hexagon of implant fixture, the point-angle areas at the corner edge of hexagon were severely worn out in both systems. It was more notable in the case of 3i systems than in that of Avana systems. 3. In the SEM view of the internal hexagon of abutment, Gingi-Hue abutment of 3i systems showed severe wear in micro-stop contacts that were machined into the corners to prevent rotation and cemented abutment of Avana systems showed wear in both surface area adjacent to the corner mating with external hexagon of implant fixture. 4. The mean values of rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment were 0.48+/-0.04 degrees in pre-tested 3i systems and 1.18+/-0.25 degrees after test, and 1.80+/-0.04 degrees in pre-tested Avana systems and 2.61+/-0.16 degrees after test. 5. Changes of rotational freedom after test showed statistically a significant increase in both 3i and Avana systems(p0.05, unpaired t-test). CONCLUSION: Conclusively, it was considered that repeated delivery and remove of abutment by 20 times would not have influence on screw joint stability. However, it caused statistically the significant change of rotational freedom in tested systems. Therefore, it is suggested that repeated delivery and remove of abutment should be minimal as possible as it could be and be done carefully. Additionally, it is suggested that the means or treatment to prevent the wear of mating components should be devised.