• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.491-497
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• 2014

PURPOSE. This study evaluated the influence of abutment materials on the stability of the implant-abutment joint in internal conical connection type implant systems. MATERIALS AND METHODS. Internal conical connection type implants, cement-retained abutments, and tungsten carbide-coated abutment screws were used. The abutments were fabricated with commercially pure grade 3 titanium (group T3), commercially pure grade 4 titanium (group T4), or Ti-6Al-4V (group TA) (n=5, each). In order to assess the amount of settlement after abutment fixation, a 30-Ncm tightening torque was applied, then the change in length before and after tightening the abutment screw was measured, and the preload exerted was recorded. The compressive bending strength was measured under the ISO14801 conditions. In order to determine whether there were significant changes in settlement, preload, and compressive bending strength before and after abutment fixation depending on abutment materials, one-way ANOVA and Tukey's HSD post-hoc test was performed. RESULTS. Group TA exhibited the smallest mean change in the combined length of the implant and abutment before and after fixation, and no difference was observed between groups T3 and T4 (P>.05). Group TA exhibited the highest preload and compressive bending strength values, followed by T4, then T3 (P<.001). CONCLUSION. The abutment material can influence the stability of the interface in internal conical connection type implant systems. The strength of the abutment material was inversely correlated with settlement, and positively correlated with compressive bending strength. Preload was inversely proportional to the frictional coefficient of the abutment material.

• The Journal of Advanced Prosthodontics
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• v.9 no.4
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• pp.271-277
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• 2017

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 ($Br{\aa}nemark$, 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 ${\alpha}=0.05$ 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 Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.192-209
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• 2004

Purpose : The purpose of this study was to evaluate the machining accuracy and consistency of implant/abutment/screw combination or internal connection type. Material and methods: In this study, each two randomly selected internal implant fixtures from ITI, 3i, Avana, Bicon, Friadent, Astra, and Paragon system were used. Each abutment was connected to the implant with 32Ncm torque value using a digital torque controller or tapping. All samples were cross-sectioned with grinder-polisher unit (Omnilap 2000 SBT Inc) after embeded in liquid unsaturated polyester (Epovia, Cray Valley Inc). Then optical microscopic and scanning electron microscopic(SEM) evaluations of the implant-abutment interfaces were conducted to assess quality of fit between the mating components. Results : 1) Generally, the geometry of the internal connection system provided for a precision fit of the implant/abutment into interface. 2) The most precision fit of the implant/abutment interface was provided in the case of Bicon System which has not screw. 3) The fit of the implant/abutment interface was usually good in the case of ITI, 3I and Avana system and the amount of fit of the implant/abutment interface was similar to each other. 4) The fit of the implant/abutment interface was usually good in the case of Friadent, Astra and Paragon system. The case of Astra system with the inclined contacting surface had the most Intimate contact among them. 5) Amount of intimate contact in the abutment screw thread to the mating fixture was larger in assembly with two-piece type which is separated screw from abutment such as Friadent, Astra and Paragon system than in that with one-piece type which is not seperated screw from abutment such as ITI, 3I and Avana system. 6) Amount of contact in the screw and the screw seat of abutment was larger in assembly of Friadent system than in asembly of Astra system of Paragon system. Conclusion: Although a little variation in machining accuracy and consistency was noted in the samples, important features of all internal connection systems were the deep, internal implant-abutment connections which provides intimate contact with the implant walls to resist micro-movement, resulting in a strong stable interface. From the results of this study, further research of the stress distribution according to the design of internal connection system will be required.

• The Journal of Advanced Prosthodontics
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• v.6 no.1
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• pp.35-38
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• 2014

PURPOSE. This study aimed to evaluate the correlation between microleakage and screw loosening at different types of implant-abutment connections and/or geometries measuring the torque values before and after the leakage tests. MATERIALS AND METHODS. Three different abutment types (Intenal hex titanium, internal hex zirconium, morse tapered titanium) with different geometries were connected to its own implant fixture. All the abutments were tightened with a standard torque value then the composition was connected to the modified fluid filtration system. After the measurements of leakage removal torque values were re-measured. Kruskal-wallis test was performed for non-parametric and one-way ANOVA was performed for parametric data. The correlation was evaluated using Spearman Correlation Test (${\alpha}=0.05$). RESULTS. Significantly higher microleakage was found at the connection of implant-internal hex zirconium abutment. Observed mean torque value loss was also significantly higher than other connection geometries. Spearman tests revealed a significant correlation between microleakage and screw loosening. CONCLUSION. Microleakage may provoke screw loosening. Removing torque values rationally decrease with the increase of microleakage.

• Journal of Periodontal and Implant Science
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• v.37 no.3
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• pp.535-542
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• 2007

Background : Repeated dis/re-connection of implant abutment caused bone loss around implant fixtures due to the new formation of biologic width of the mucosal-implant barrier. The aim of this clinical study was to evaluate whether the repeated dis/re-connection of implant abutment cause bone loss clinically and the effect of cleansing methods on a bone loss during the early healing period. Methods : A total 50 implants were installed in 20 patients and repeated dis/re-connection of abutment was performed at the time of surgery and once per week for 12 weeks. 0.9% normal saline solution as group1 and 0.1% chlorhexidine solution as group 2 was used to clean abutments. All patients had radiographs taken at the placement of implant and 4, 8, and 12 weeks postoperatively. The data for bone loss around implant were analyzed. Results: The marginal bone loss at 12 weeks were $1.28{\pm}0.51mm$, $1,32{\pm}0,57mm$ in the mesial and distal sides in group1, $1.94{\pm}0.75mm$, $1.81{\pm}0.84mm$ in group 2, respectively. In view of marginal bone loss, there was not a significant statistical difference between groups. Conclusions : Repeated dis/re-connection of implant abutment may not cause marginal bone loss around implant fixture although limited samples and short-term observation period. In spite of more bone loss in group 2, there was no statistical significant difference between groups. In context of those results, the clinical significance of the repeated dis/re-connection of implant abutment and the cleansing method of abutments is debatable when it comes to marginal bone loss during early healing period.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.4
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• pp.309-318
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• 2013

Abutment-to-pile connection in an integral abutment bridge is vulnerable to lateral displacement induced by thermal movement of the superstructure. However, previous researches have merely focused on the connection. In order to improve the performance of the connection, new abutment-to-pile connection designs were proposed based on quasi-static nonlinear finite element model. The reinforcement detail specified in PennDOT DM4 and HSS tube were barely effective in controlling crack growing but spiral rebar effectively performed to delay crack growth as well as absorbing energy capacity. However, it was found that delaying cracking and strengthening the connection also caused the high lateral load in superstructures. Consequently, shape of HP pile were modified to introduce plastic hinge of the HP pile for reducing the lateral load in superstructures. Connections with modified HP pile significantly prevented crack propagations under the lateral displacement.

• International Journal of Clinical Preventive Dentistry
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• v.14 no.4
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• pp.247-255
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• 2018

Objective: Osseointegration is essential process for successful implants and effects to implant in long term, therefore, passive fitness of good prosthesis is necessary. To make a good prosthesis, at first it should be done a sectioned casting and then joined method of sectioned casting body is recommended. Methods: In this study, to provide the fundamental data on stable connection method for successful implants, the author tested fitness of casting body, and compared difference between gas soldering technique and laser welding technique. Results: In fitness test of 2 abutment (test A, C), gas soldering group's fitness in the opposite part of connection was worse than laser welding group. In fitness test of 3 abutment (test B, D), gap distance was increased both in gas soldering technique and laser welding technique. Gap distance at the connecting part and the opposite part of the abutment in gas soldering technique was worse than laser welding technique and the more additional abutment, the worse gap distance in gas soldering technique. In fitness test of 3 abutment (test B, D), there's little variation in No. 2 abutment when connecting soldering process was done and there's little influence on already soldered connection part when the additional soldering connection was done. Conclusion: On weak loading condition and the part which is needed an accuracy, laser welding technique is more effective and on long-span prosthesis and frequent chewing loading part, laser welding technique is recommended first and applying additional gas soldering technique would be better for making much more successful prosthesis.

• Structural Engineering and Mechanics
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• v.59 no.2
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• pp.209-226
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• 2016

Integral bridges are typically designed with flexible foundations that include one row of piles. The construction of integral bridges solves difficulties due to the maintenance of expansion joints and bearings during serviceability. It causes integral bridges to become more economic comparing with conventional bridges. Research has been focused not only to enhance the seismic performance of newly designed bridges, but also to develop retrofit strategies for existing ones. The local performance of the pile to abutment connection will have a major effect on the performance of the structure and the embedment length of pile inside the abutment has a key role to provide shear and flexural resistance of pile-abutment connections. In this paper, a simple method was developed to estimate the initial value of embedment length of the pile for retrofitting of specimens. Four specimens of pile-abutment connections were constructed with different embedment lengths of pile inside the abutment to evaluate their performances. The results of the experimentation in conjunction with numerical and analytical studies showed that retrofitting pile-abutment connections with CFRP wraps increased the strength of the connection up to 86%. Also, designed connections with the proposed method had sufficient resistance against lateral load.

• The Journal of Advanced Prosthodontics
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• v.11 no.2
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• pp.105-111
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• 2019

PURPOSE. Limited data is available regarding the differences for possible microleakage problems and fitting accuracy of zirconia versus titanium abutments with various connection designs. The purpose of this in vitro study was to investigate the effect of connection design and abutment material on the sealing capability and fitting accuracy of abutments. MATERIALS AND METHODS. A total of 42 abutments with different connection designs [internal conical (IC), internal tri-channel (IT), and external hexagonal (EH)] and abutment materials [titanium (Ti) and zirconia (Zr)] were evaluated. The inner parts of implants were inoculated with $0.7{\mu}L$ of polymicrobial culture (P. gingivalis, T. forsythia, T. denticola and F. nucleatum) and connected with their respective abutments under sterile conditions. The penetration of bacteria into the surrounding media was assessed by the visual evaluation of turbidity at each time point and the number of colony forming units (CFUs) was counted. The marginal gap at the implant- abutment interface (IAI) was measured by scanning electron microscope. The data sets were statistically analyzed using Kruskal-Wallis followed by Mann-Whitney U tests with the Bonferroni-Holm correction (${\alpha}=.05$). RESULTS. Statistically significant difference was found among the groups based on the results of leaked colonies (P<.05). The EH-Ti group characterized by an external hexagonal connection were less resistant to bacterial leakage than the groups EH-Zr, IT-Zr, IT-Ti, IC-Zr, and IC-Ti (P<.05). The marginal misfit (in ${\mu}m$) of the groups were in the range of 2.7-4.0 (IC-Zr), 1.8-5.3 (IC-Ti), 6.5-17.1 (IT-Zr), 5.4-12.0 (IT-Ti), 16.8-22.7 (EH-Zr), and 10.3-15.4 (EH-Ti). CONCLUSION. The sealing capability and marginal fit of abutments were affected by the type of abutment material and connection design.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.346-353
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• 2011

Purpose: The peri-implant soft tissue is remodeled by the initial marginal bone resorption affecting the prognosis and esthetic result of treatment. Thus various designs on implant neck design are studied to preserve peri-implant bone. The purpose of this study is to review on the causes of initial marginal bone resorption, the configuration of peri-implant soft tissue, and the implant crestal module favorable in preserving peri-implant tissue. Materials and methods: The studies on the causes of initial marginal bone resorption and the implant crestal modules are researched and reviewed using Pubmed database. The implant crestal modules including one piece and two-piece implant, internal and external hex abutment, taper and butt joint connection, scalloped design abutment, and platform switching concept are reviewed. Results: A number of clinical and experimental studies preferred one piece implant to two-piece in preserving initial peri-implant tissue. For two piece implants, internal hex abutment and taper joint connection appear more favorable than external hex abutment and butt joint connection relatively. Controversial issues still exist on scalloped design requiring more studies on it. Although the rationale is not certain, the concept of platform switching seems favorable in preserving initial peri-implant tissue based on clinical and experimental studies. Conclusion: Each implant crestal module contains its own advantages and disadvantages with various controversial issues. In the aspect of preservation of initial peri-implant tissue, however, one-piece implant seems beneficial. In cases when two-piece implant is more appropriate due to prosthodontic concerns or any other problems, the application of platform switching concept, internal connection abutment, and taper joint connection may be favorable for the preservation of peri-implant tissues.