• The Journal of Korean Academy of Prosthodontics
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• v.46 no.3
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• pp.246-254
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• 2008

STATEMENT OF PROBLEM: The cast abutment has advantages of overcoming angulation problem and esthetic problem. However, when a gold-machined UCLA abutment undergoes casting, the abutment surfaces in contact with the implant may change. PURPOSE: The purpose of this study was to compare the detorque values of prefabricated machined abutments with gold-premachined cast-on UCLA abutments before and after casting in two types of internal implant-abutment connection systems: (1) internal hexagonal joint, (2) internal octagonal joint. Furthermore, the detorque values of two implant-abutment connection systems were compared. MATERIALS AND METHODS: Twenty internal hexagonal implants with an 11-degree taper and twenty internal octagonal implants with an 8-degree taper were acquired. Ten prefabricated titanium abutments and ten gold-premachined UCLA abutments were used for each systems. Each abutment was torqued to 30 N㎝ according to the manufacturer's instructions and detorque value was recorded. The detorque values were measured once more, after casting with gold alloy for UCLA abutment, and preparation for titanium abutments. Group means were calculated and compared using independent t-test and paired t-test (${\alpha}$=0.05). RESULTS: The results were as follows: 1. The detorque values between titanium abutments and UCLA-type abutments showed significant differences in internal octagonal implants (P<0.05), not in internal hexagonal implants (P>0.05). 2. In comparison of internal hexagonal and octagonal implants, the detorque values of titanium abutments had significant differences between two connection systems on the initial analysis (P<0.05), not on the second analysis (P>0.05) and the detorque values of UCLA-type abutments were not significantly different between two connection systems (P>0.05). 3. The detorque values of titanium abutments and UCLA-type abutments decreased significantly on the second analysis than the initial analysis in internal hexagonal implants (P<0.05), not in internal octagonal implants (P>0.05). CONCLUSION: Casting procedures of UCLA-type abutments had no significant effect on screw loosening in internal implant-abutment connection systems, and UCLA-type abutments showed higher detorque values than titanium abutments in internal octagonal implants.

• The Journal of Advanced Prosthodontics
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• v.10 no.6
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• pp.415-421
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• 2018

PURPOSE. This study investigated the effects of abutment screw lengths on screw loosening and removal torque in external connection implants after oblique cyclic loading. MATERIALS AND METHODS. External connection implants were secured with abutment screws to straight abutments. The abutment-implant assemblies were classified into seven groups based on the abutment screw length, with each group consisting of five assemblies. A cyclic load of 300 N was applied at a $30^{\circ}$ angle to the loading axis until one million cycles were achieved. Removal torque values (RTVs) before and after loading, and RTV differences were evaluated. The measured values were analyzed using repeated measures of analysis of variance with the Student-Newman-Keuls multiple comparisons. RESULTS. All assemblies survived the oblique cyclic loading test without screw loosening. There was a significant decrease in the RTVs throughout the observed abutment screw lengths when the abutment-implant assemblies were loaded repeatedly (P<.001). However, the abutment screw length did not show significant difference on the RTVs before and after the experiment when the abutment screw length ranged from 1.4 to 3.8 mm (P=.647). CONCLUSION. Within the limit of this experiment, our results indicate that the abutment screw length did not significantly affect RTV differences after oblique cyclic loading when a minimum length of 1.4 mm (3.5 threads) was engaged. These findings suggest that short abutment screws may yield stable clinical outcomes comparable to long screws in terms of load resistance.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.226-237
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• 2004

Purpose: Four finite element models were constructed in the mandible having a single implant fixture connected to the first premolar-shaped superstructure, in order to evaluate how the shape of the fixture and the implant-abutment connection would influence the stress level of the supporting tissues fixtures, and prosthethic components. Material and methods : The superstructures were constructed using UCLA type abutment, ADA type III gold alloy was used to fabricate a crown and then connected to the fixture with an abutment screw. The models BRA, END , FRI, ITI were constructed from the mandible implanted with Branemark, Endopore, Frialit-2, I.T.I. systems respectively. In each model, 150 N of vertical load was placed on the central pit of an occlusal plane and 150 N of $40^{\circ}$ oblique load was placed on the buccal cusp. The displacement and stress distribution in the supporting tissues and the other components were analysed using a 2-dimensional finite element analysis . The maximum stress in each reference area was compared. Results : 1. Under $40^{\circ}$ oblique loading, the maximum stress was larger in the implant, superstructure and supporting tissue, compared to the stress pattern under vertical loading. 2. In the implant, prosthesis and supporting tissue, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 3. In the superstructure and implant/abutment interface, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 4. In the implant fixture, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 5 The stress was more evenly distributed in the bone/implant interface through the FRI of trapezoidal step design. Especially Under $40^{\circ}$ oblique loading, The maximum stress was smallest in the bone/implant interface. 6. In the implant and superstructure and supporting tissue, the maximum stress occured at the crown loading point through the ITI. Conclusion: The stress distribution of the supporting tissue was affected by shape of a fixture and implant-abutment connection. The magnitude of maximum stress was reduced with the internal connection type (FRI) and the morse taper type (ITI) in the implant, prosthesis and supporting tissue. Trapezoidal step design of FRI showed evenly distributed the stress at the bone/implant interface.

• Journal of Periodontal and Implant Science
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• v.52 no.6
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• pp.496-508
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• 2022

Purpose: This study aimed to compare the long-term survival rate and peri-implant marginal bone loss between different types of dental implant-abutment connections. Methods: Implants with external or internal abutment connections, which were fitted at Gangneung-Wonju National University Dental Hospital from November 2011 to December 2015 and followed up for >5 years, were retrospectively investigated. Cumulative survival rates were evaluated for >5 years, and peri-implant marginal bone loss was evaluated at 1- and 5-year follow-up examinations after functional loading. Results: The 8-year cumulative survival rates were 93.3% and 90.7% in the external and internal connection types, respectively (P=0.353). The mean values of marginal bone loss were 1.23 mm (external) and 0.72 mm (internal) (P<0.001) after 1 year of loading, and 1.20 mm and 1.00 mm for external and internal abutment connections, respectively (P=0.137) after 5 years. Implant length (longer, P=0.018), smoking status (heavy, P=0.001), and prosthetic type (bridge, P=0.004) were associated with significantly greater marginal bone loss, and the use of screw-cement-retained prosthesis was significantly associated (P=0.027) with less marginal bone loss. Conclusions: There was no significant difference in the cumulative survival rate between implants with external and internal abutment connections. After 1 year of loading, marginal bone loss was greater around the implants with an external abutment connection. However, no significant difference between the external and internal connection groups was found after 5 years. Both types of abutment connections are viable treatment options for the reconstruction of partially edentulous ridges.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.249-258
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• 2012

Integral and rigid frame bridges have advantages in bridge maintenance and structural efficiency by eliminating expansion joints and bridge supports. However, the detail of typical girder-abutment connection is rather complex and increases construction cost depending on construction detail. For the purpose of compensating disadvantages such as complexity and additional cost, a new type of bridge is proposed in this study, which improves the efficiency of construction by simplifying the construction detail of girder-abutment connection. The proposed bridge has the connection detail of steel girder and abutment integrated by prestressed PS bar installed in the connection. In this study, finite element analysis and fatigue load test are conducted to evaluate the fatigue capacity of the proposed girder-abutment connection. The results of the finite element analysis revealed that the possibility of the fatigue damage in the girder-abutment connection is very low. The results of the fatigue load test verified that the integrity of the girder and abutment connection is maintained after 2,000,000 cycles of fatigue loading.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.1
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• pp.9-17
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• 2017

Purpose: The purpose of this study was to evaluate the fracture strength of straight and angled zirconia abutments for internal hex and external hex implants. Materials and methods: Twenty internal hex implants and 20 external hex implants were prepared. The prefabricated straight zirconia abutments and 17-degree-angled zirconia abutments were connected to those 40 implants. The specimens were classified into 4 groups depending on the connection type and abutment angulation; internal hex implant/straight abutment, group INS; internal hex implant/angled abutment, group INA; external hex implant/straight abutment, group EXS; external hex implant/angled abutment, group EXA. All specimens were loaded at a 30-degree angle with a crosshead speed of 1 mm/min using universal testing machine. The fracture loads were analyzed using 2-way ANOVA and independent t-test (${\alpha}=.05$). Results: The mean fracture load for INS was 955.91 N, 933.65 N for INA, 1267.20 N for EXS, and 1405.93 N for EXA. External hex implant showed a significantly higher fracture load, as compared to internal hex implant (P < .001). No significant differences in fracture loads were observed between the straight and angled abutment in internal hex implants (P = .747) and external hex implants (P = .222). Internal hexes of abutments were fractured horizontally in internal connection implants, while lingual cervical neck portions were fractured in external connection implants. Conclusion: The zirconia abutments with external hex implants showed significantly higher fracture strength than those with internal hex implants. However there was no difference in fracture strength between the straight and 17-degree-angled zirconia abutment connected to both implant systems.

• The Journal of Advanced Prosthodontics
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• v.1 no.1
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• pp.37-40
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• 2009

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($4.5{\times}12\;mm$ Xive, $4.3{\times}11.5\;mm$ Inplant Magicgrip, $4.3{\times}12\;mm$ 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.

• The Journal of the Korean dental association
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• v.56 no.11
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• pp.605-614
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• 2018

PURPOSE. The purpose of this study is to determine the efficacy of the DENTIS submerged-type implant with an internal hex connection and to build corresponding abutment-selection criteria. MATERIAL AND METHODS. A total of 204 patients received submerged implant fixtures with an internal hex connection at the Dong-A University Hospital Dental clinic in Busan from January 2013 and May 2016. Three specific abutments, UCLA abutments, customized abutments, ready-made abutments, were randomly selected. Implant success was defined as the basis of the International Congress of Oral Implantologists(ICOI, 2007) criteria. The relationship between the implant success rate and the abutment factor was analyzed using the Kruskal-Wallis test(P<.05). RESULTS. A total of 508 implants were placed in 204 patients. After a mean observation period of 38.6 months, 493 out of 508 implants were in normal function, yielding an overall success rate of 97.05%. A total of 15 implants failed: 10 in the maxillary molar area, 4 in the mandibular molar area, and 1 in the mandibular incisal area. All of the implant failures occurred in a single-implant prosthesis, especially high in the maxillary molar area. The Kruskal-Wallis analysis showed that abutment selection has no significant correlation with implant failure(P>.05). CONCLUSION. DENTIS submerged implants with an internal hex connection showed predictable results with a success rate of 97.05%. It is no influence on the success rate in the selection of submerged implant abutment with an internal hex connection.

• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.453-463
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• 2012

Steel-concrete composite rigid-frame bridge is a type of integral bridge having advantages in bridge maintenance and structural efficiency from eliminating expansion joints and bridge supports, the main problems in bridge maintenance. The typical steel-concrete composite rigid-frame bridge has the girder-abutment connection where a part of its steel girder is embedded in abutment for integrity. However, the detail of typical girder-abutment connection is complex and increases the construction cost, especially when a part of steel girder is embedded. Recently, a new type of bridge was proposed to compensate for the disadvantages of complex details and cost increase. The compensation are expected to improve efficiency of construction by simplifying the construction detail of the girder-abutment connection. In this study, a static load test has been carried out to examine the behavior of the girder-abutment connection using real-scale specimens. The results of the test showed that the girder-abutment connection of proposed girder bridge has sufficient flexural capacity and rebars to control concrete crack should be placed on the top of abutment.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.3
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• pp.379-392
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• 2005

Statement of problem. One of the common problems of dental implant prosthesis is the loosening of the screw that connects each component, and this problem is more common in single implant-supported prostheses with external connection, and in molars. Purpose. The purposes of this study were: (1) to compare the initial abutment screw detorque values of the six different implant-abutment interface designs, (2) to compare the detorque values of the six different implant-abutment interface designs after cyclic loading, (3) to compare the detorque values of regular and wide diameter implants and (4) to compare the initial detorque values with the detorque values after cyclic loading. Material and methods. Six different implant-abutment connection systems were used. The cement retained abutment and titanium screw of each system were assembled and tightened to 32Ncm with digital torque gauge. After 10 minutes, initial detorque values were measured. The custom titanium crown were cemented temporarily and a cyclic sine curve load(20 to 320N, 14Hz) was applied. The detorque values were measured after cyclic loading of one million times by loading machine. One-way ANOVA test, scheffe’s test and Mann-Whitney U test were used. Results. The results were as follows : 1. The initial detorque values of six different implant-abutment connections were not significantly different(p>0.05). 2. The detorque values after one million dynamic cyclic loading were significantly different (p<0.05). 3. The SS-II regular and wide implant both recorded the higher detorque values than other groups after cyclic loading(p<0.05). 4. Of the wide implants, the initial detorque values of Avana Self Tapping Implant, MIS and Tapered Screw Vent, and the detorque values of MIS implant after cyclic loading were higher than their regular counterparts(p<0.05). 5. After cyclic loading, SS-II regular and wide implants showed higher detorque values than before(p<0.05).