• The Journal of Korean Academy of Prosthodontics
• /
• v.50 no.2
• /
• pp.92-98
• /
• 2012

Purpose: The aim of this study was to evaluate the effects of different abutment materials on abutment screw loosening and settling-down effect in conical connection type implant system. Materials and methods: Three types of abutment, cementation, gold UCLA, and metal UCLA abutment were used. Two UCLA groups were fabricated in a similar pattern to cementation abutment. Type III gold alloy and Nickel-Chromium alloy was used for casting gold UCLA abutment and metal UCLA abutment, respectively. Fixture and abutment were tightened to 30 Ncm by using digital torque controller and re-tightening was conducted with same force after 10 minutes. Digital torque gauge was used to measure loosening torque and fixture/abutment length was measured by digital micrometer. Dynamic loads between 25 N and 250 N were applied with $0^{\circ}$ angle to the abutment axis. After loading, fixture/abutment length was re-measured and amount of settlement was calculated. Loosening torque value was also measured for comparison Results: All three groups showed significant differences of length when comparing before and after loading, but there was no significant difference of settling amount in all groups. Loosening torque values were significantly decreased when comparing before and after loading in all groups($P$<.05). However, there was no significant difference in loss of loosening torque values when compared to groups. Conclusion: In internal conical connection type implants, dynamic load affected on settlement and loosening torque of implant, but there was no differences between abutments materials. Likewise gold UCLA abutment, metal UCLA abutment might be able to withstand functional load.

• The Journal of Korean Academy of Prosthodontics
• /
• v.50 no.2
• /
• pp.128-134
• /
• 2012

Purpose: The purpose of this study was to compare the screw joint stability between the CADCAM custom-made implant abutment and the prefabricated implant abutment by measuring the reverse torque value after cyclic loading. Materials and methods: Twelve screw type implants (Implantium, Dentium Co., Seoul, Korea) were embedded in aluminum cylinder with acrylic resin. The implant specimens were equally divided into 3 groups, and connected to the prefabricated titanium abutments (Implantium, Dentium Co., Seoul, Korea), CADCAM custom-made titanium abutments (Myplant, Raphabio Co., Seoul, Korea) and CADCAM custom-made zirconia abutments (Zirconia Myplant, Raphabio Co., Seoul, Korea). The CAD-CAM milled titanium crown (Raphabio Co., Seoul, Korea) was cemented on each implant abutment by resin cement. Before cyclic loading, each abutment screw was tightened to 30 Ncm and the reverse torque value was measured about 30 minutes later. After the crown specimen was subjected to the sinusoidal cyclic loading (30 to 120 N, 500,000 cycles, 2 Hz), postloading reverse torque value was measured and the reverse torque loss ratio was calculated. Kruskal-Wallis test was used for statistical analysis of the reverse torque loss ratio. Results: The CADCAM custom-made titanium abutments presented higher values in reverse torque loss ratio without statistically significant differences than the prefabricated titanium abutments ($P$>.05). Reverse torque loss ratio of the custom-made zirconia abutments was significantly higher compared to that of the prefabricated titanium abutments ($P$=.014). Conclusion: Within the limitation of the present $in-vitro$ study, it was concluded that there was no significant difference in screw joint stability between the CADCAM custom-made titanium abutments and the prefabricated titanium abutments. On the other hand, the CADCAM custom-made zirconia abutments showed lower screw joint stability than prefabricated titanium abutments.

• The Journal of Korean Academy of Prosthodontics
• /
• v.54 no.4
• /
• pp.387-392
• /
• 2016

Purpose: The aim of this study was to investigate the effects of grooved abutments on abutment screw loosening. Materials and methods: This study was conducted to evaluate the abutment screw loosening after 6 months for 50 patients (51 implants) treated at the department of Prosthodontics in Yonsei University Dental Hospital from March, 2015 to July, 2015. A control group with non-grooved abutment consists of 30 implants, and an experimental group with grooved abutment consists of 21 implants. Astra, Straumann, Implantium, Osstem system were used in the study. The abutments with loose screws cases after a period of 6 months has been investigated, with two kinds of measurements: 1) measuring the additional rotational angle on abutment during placement with the same force, 2) measuring the PTV on bucco-cervical area of implant crown. All data collected has been analyzed by normality test followed by Mann-Whitney test using SPSS program. Results: No complications were reported after 6 months for the 51 implants. Abutment screw loose and crown fracture have not been seen in the study groups. The data collected from the two measurements showed no significant differences between the two groups with P-value 0.576 (average= control group: $7.35^{\circ}$, experimental group: $4.75^{\circ}$) for the additional rotational angle measurement and with P-value 0.767 for PTV. Conclusion: There are no significant differences between the grooved and non-grooved abutment in screw stability. However, further studies with long-term followups and larger group of patients is needed in order to investigate the effects of grooved abutment on screw stability.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.31 no.1
• /
• pp.50-59
• /
• 2015

It is hard to restore and manage anterior teeth esthetically and functionally; because of peri-implantitis, not only hard and soft tissue problem such as alveolar bone resorption and interdental papilla loss but also esthetic problem caused by metal abutment exposure can occur. This case presents patients using customized abutment made of Co-Cr alloy that can be made by conventional casting and compensate the shortcomings of prefabricated titanium abutments, and cement-retained prosthesis.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.28 no.2
• /
• pp.127-138
• /
• 2012

This study is to assess the effect of preload level on the stress development at the marginal cortical bone surrounding implant neck. A finite element model was created for a single implant placed in the lower jaw bone. An external load of 100N was applied on the top of abutment at 30 degree with the implant axis in lingo-buccal direction. Five different preloads, i.e. 0, 200, 400, 600, 800N were applied to the abutment stem to investigate if and/or how the preload affects on the marginal bone stress. Differences in the marginal bone stress were recorded depending on the level of preload. On the other hand, the tensile stress on the marginal cortical bone decreased in models of higher preload. Preloads between abutment/fixture can increase compressive stresses in the marginal cortical bone although the amount may be insignificant as compared to those generated by functional forces.

• The Journal of Korean Academy of Prosthodontics
• /
• v.47 no.2
• /
• pp.164-173
• /
• 2009

Purpose: The purpose of this study was to evaluate the effect of abutment material on screw-loosening before and after cyclic loading. Among the different materials of abutments, zirconia and metal abutment were used. Material and methods: Two types of implant systems: external butt joint(US II, Osstem Implant, Korea) and internal conical joint(GS II, Osstem Implant, Korea) were used. In each type, specimens were divided into two different kinds of abutments: zirconia and metal(n=5). The implant was rigidly held in a special holding to device ensure fixation. Abutment was connected to 30 Ncm with digital torque gauge, and was retightened in 30 Ncm after 10 minutes. The initial removal torque values were measured. The same specimens were tightened in 30 Ncm again and held in the cycling loading simulator(Instron, USA) according to ISO/FPIS 1480. Cycling loading tests were performed at loads 10 to 250 N, for 1 million cycles, at 14 Hz,(by subjecting sinusoidal wave from 10 to 250 N at a frequency of 14 Hz for 1 million cycles,) and then postload removal torque values were evaluated. Results: 1. In all samples, the removal values of abutment screw were lower than tightening torque values(30 Ncm), but the phenomenon of the screw loosening was not observed. 2. In both of the implant systems, initial and postload removal torque of zirconia abutment were significantly higher than those of metal abutment(P<.05). 3. In both of the implant systems, the difference in removal torque ratio between zirconia abutment and metal abutment was not significant(P>.05). 4. In metal abutments, the removal torque ratio of GS II system(internal conical joint system) was lower than that of US II system(external butt joint system)(P<.05). 5. In zirconia abutments, the difference in removal torque ratio between the two implant systems was not significant(P>.05). Conclusion: Zirconia abutment had a good screw joint stability in the condition of one million cycling loading.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.40 no.2
• /
• pp.64-71
• /
• 2024

Purpose: The purpose of this study is to evaluate Ti-base abutment's three different heights and three different cement types on the pull-off force of zirconia-based restorations. Materials and Methods: A total of 90 fixture lab analogs were embedded in auto polymerizing resin bloack. 90 Ti-base abutments heights of 3 mm, 5 mm, 7 mm were scanned and zirconia restoration were prepared from scanned files. Zirconia restoration were cemented with three different types of cements (temporary, semi-permanent, permanent) following manufacturer's instructions. All 90 specimens were placed and tested in a universal testing machine for pull-out testing. Retention was measured by recording the force at load drop. Statistical analysis was performed using Kruskal-Wallis test for detecting whether there are any statistical significance along cement types or abutment heights. After that, Mann-Whitney test was used for figuring out differences regarding abutment height and the comparison between 3 cements. Results: Temp bond showed significantly lower pull-off force compared to Fujicem regardless of any abutment height. However, there were significant differences between Cem-implant and Fujicem in abutment height of 3 mm and 7 mm, but there was no significant difference in 5 mm. Temp bond and Cem-implant had significant differences only in abutment height of 5 mm. Conclusion: Although Ti-base abutment height did not influenced zirconia restorations' retentiveness, cement types showed significant differences.

• The Journal of Korean Academy of Prosthodontics
• /
• v.55 no.3
• /
• pp.251-257
• /
• 2017

Purpose: The purpose of this study was to evaluate whether the internal abutment length affected screw stability in an internal connection implant. Materials and methods: Twenty long internal connection implants (Replus system, $4.7{\times}11.5mm$) were selected for this investigation. Abutments were assigned to four groups depending on the length of the internal connection (abutments with internal lengths of 1, 2, 3, and 4 mm, respectively). Each implant fixture specimen was embedded in resin medium and connected to an abutment with an abutment screw. A load of 100 N, applied at an angle of $30^{\circ}$ to the long axis of the implant, was repeated for $1.0{\times}10^6$ cycles. Reverse torque values (RTV) were recorded before and after loading, and the change in RTV was calculated. Data were analyzed with the Kruskal-Wallis test. Results: The change in RTV was not significantly different among the groups (P>.05). Screw loosening and fractures were not observed in any groups, and joint stability was maintained. Conclusion: The internal length of the abutment may not significantly affect the degree of screw loosening.

• The Journal of Korean Academy of Prosthodontics
• /
• v.54 no.4
• /
• pp.370-378
• /
• 2016

Purpose: The purpose of this study was to investigate screw joint stability and sagittal fit between internal connection implant fixtures of two different manufacturers and customized abutments. Materials and methods: Internal connection implant systems from two different manufacturers (Biomet 3i system, Astra Tech system) were selected for this study (n=24 for each implant system, total n=48). For 3i implant system, half of the implants were connected with Ti ready-made abutments and the other half implants were connected with Ti CAD-CAM custom ones of domestic-make (Myplant, Raphabio Co., Seoul, Korea) and were classified into Group 1 and Group 2 respectively. Astra implants were divided into Group 3 and Group 4 in the same way. Micro-CT sagittal imaging was performed for fit analysis of interfaces and preloading reverse torque values (RTV) were measured. Results: In the contact length of fixture-abutment interface, there were no significant differences not only between Group 1 and Group 2 but also between Group 3 and Group 4 (Mann-Whitney test, P>.05). However, Group 2 and Group 4 showed higher contact length significantly than Group 1 and Group 3 in abutment-screw interface as well as fixture-screw one (Mann-Whitney test, P<.05). In addition, RTV was lower in CAD-CAM custom abutments compared to ready-made ones (Student t-test, P<.05). Conclusion: It is considered that domestically manufactured CAD-CAM custom abutments have similar fit at the fixture abutment interface and it could be used clinically. However, RTV of CAD-CAM custom abutments should be improved for the increase of clinical application.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.36 no.2
• /
• pp.95-103
• /
• 2020

Purpose: The purpose of this study was to compare the axial displacement of the hexagonal and conical abutment in internal conical connection implant after screw tightening and cyclic loading. Materials and Methods: Internal conical connection implants were divided into two groups (n = 10): group HEX, hexagonal abutment; and group CON, conical 2-piece abutments. The axial displacement and removal torque values were measured after 30 Ncm torque tightening and 250N loading test of 100,000 cycles. The Student t test with 5% significance level was used to evaluate the data. Results: HEX group demonstrated significantly higher axial displacement values after 30 Ncm tightening in comparison to the CON group (P < 0.05). No significant difference was found in axial displacement after cyclic loading (P = 0.052). Removal torque loss before and after the cyclic loading both revealed no significant difference between groups (P = 0.057 and P = 0.138). Removal torque value decreased after cyclic loading in both groups (P < 0.05). Conclusion: Overall, both abutment with or without hexagon index presented similar biomechanical performance except HEX group demonstrated significantly more axial displacement after applying tightening torque.