• The Journal of the Korean dental association
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• v.54 no.3
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• pp.184-190
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• 2016

The osseointegration of titanium implants has been examined over the past 50 years. Many implant systems have been introduced and have become popular to the implant dentistry. The designs of the connection between implant fixture and abutment are divided into external vs internal connection. From beginning, the $Br{\aa}nemark$ system was characterized by an external hexagon. Internal connection has been developed to reduce stress transferred to the bone. These differences may have impact on the clinical procedures and protocols, laboratory and components costs, and incidence of complications. Therefore, the clinician has to know the different biomechanical features and understand their implications to produce successful implant-supported prosthesis with an external or an internal connection system.

• The Journal of the Korean dental association
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• v.54 no.3
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• pp.198-205
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• 2016

The purpose of this paper was to investigate the significance of splinted and non-splinted implant-supported restorations with an internal connection for multiple consecutively missing teeth. Upon examination of the effects of fixture-abutment connection, the distribution of occlusal load was favorable in splinted implant-prosthesis with an external connection, but effect of strain distribution was not significant in splinted implant-prosthesis with an internal connection. In splinted implant-prostheses for short implants, strain distribution was not affected by the method of retention. For cement-retained prostheses, the effect of strain distribution due to splinting was not significant. In clinical studies, non-splinted prostheses with an internal connection for multiple consecutively missing teeth showed high survival rate, mild marginal bone loss, and stable periodontal condition. However, failure to achieve optimal proximal contact between single-unit prostheses may lead to food impaction, and veneer fracture may be inevitable when the framework provides inadequate support in the proximal region. In conclusion, splinted implant-prosthesis is not an indication in all cases, and clinical consideration of its use should be based on the patient's oral condition, such as location and number of implants, formation of proximal contact, canine guidance, existence of parafunctional habit, and oral hygiene, when multiple consecutively missing teeth are replaced by internal connection type implant.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.3
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• pp.338-351
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• 2005

Statement of problem. Accurate fit between the implant components is important because the misfit of the implant components results in frequent screw loosening, irreversible screw fracture, plaque accumulation, poor soft tissue reaction, and destruction of osseointegration. Purpose. This study is to evaluate the machining accuracy and consistency of the implant fixture/ abutment/screw interfaces of the internal connection system by using a Stereoscopic Zoom microscope and FE-SEM(field emission scanning electron microscope) Materials and methods. The implant systems selected in this study were internal connection type implants from AVANA(Osstem^{\circledR}), Bioplant(Cowell-Medi^{\circledR}), Dio(DIO^{\circledR}), Neoplant(Neobiotech 􀋓), Implantium(Dentium􀋓)systems. Each group was acquired 2 fixtures at random. Two piece type abutment and one piece type abutment for use with each implant system were acquired. Screw were respectively used to hold a two piece type abutment to a implant fixture. The implant fixtures were perpendiculary mounted in acrylic resin block. Each two piece abutment was secured to the implant fixture by screw and one piece abutment also secured to the implant fixture. Abutment/fixture assembly were mounted in liquid unsaturated polyester. All samples were cross-sectioned with grinder-polisher unit. Finally all specimens were analysed the fit between implant fixture/abutment/screw interfaces Results and conclusions. 1. Implant fixture/abutment/screw connection interfaces of internal connection systems made in Korea were in good condition. 2. The results of the above study showed that materials and mechanical properties and quality of milling differed depending on their manufacturing companies.

• 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.

• 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 Korean Academy of Prosthodontics
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• v.41 no.4
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• pp.393-404
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• 2003

Statement of problem. Higher incidence of prosthetic complications such as screw loosening, screw fracture has been reported for posterior single tooth implant. So, there is ongoing research regarding stability of implant-abutment interface. One of those research is increasing the implant diameter and prosthetic table width to improve joint stability. In another part of this research, internal conical type implant-abutment interface was developed and reported joint strength is higher than traditional external hex interface. Purpose. The purpose of this study is to compare stress distribution in single molar implant between external hex butt joint implant and internal conical joint implant when increasing the implant diameter and prosthetic table width : 4mm diameter, 5mm diameter, 5mm diameter/6mm prosthetic table width. Material and method. Non-linear finite element models were created and the 3-dimensional finite element analysis was performed to see the distribution of stress when 300N static loading was applied to model at $0^{\circ},\;15^{\circ},\;30^{\circ}$ off-axis angle. Results. The following results were obtained : 1. Internal conical joint showed lower tensile stress value than that of external hex butt joint. 2. When off-axis loading was applied, internal conical joint showed more effective stress distribution than external hex butt joint. 3. External hex butt joint showed lower tensile stress value when the implant diameter was increased. 4. Internal conical joint showed lower tensile stress value than external hex butt joint when the implant diameter was increased. 5. Both of these joint mechanism showed lower tensile stress value when the prosthetic table width was increased. Conclusion. Internal conical joint showed more effective stress distribution than external hex joint. Increasing implant diameter showed more effective stress distribution than increasing prosthetic table width.

• The Journal of the Korean dental association
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• v.53 no.5
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• pp.360-367
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• 2015

Purpose : The purpose of this study was to evaluate the effect of amount of cantilever in intra-crown according to implant fixture position on mechanical strength of internal conical joint type implant. Materials and Methods : Internal conical joint type implant fixture, abutment screw, abutment was connected and gold alloy prostheses were fabricated and cemented on abutment. For fatigue fracture test, the specimens were loaded to the 350 N, 2,000,000 cycle on 3, 4, 5, and 6 mm off-center of gold alloy prostheses. The fracture pattern of implant component was observed. Results : No fatigue fracture found on 3 and 4 mm group. But initial crack pattern found on 3 specimens of 4 mm group. Fatigue fracture found on all specimens of 5 mm group. But complete fracture was not observed. One specimen of 6 mm group fracture completely. Implant fixture fracture wax not observed. Conclusion : The mechanical failure of implant prostheses increased with the loading area farther from center of implant fixture. To reduce mechanical problem of internal joint type implant, surgical and prosthetic consideration is needed.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.4
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• pp.356-372
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• 2004

Statement of problom: In the internal connection system the loading transfer mechanism within the inner surface of the implant and also the stress distribution occuring to the mandible can be changed according to the abutment form. Therefore it is thought to be imperative to study the difference of the stress distribution occuring at the mandible according to the abutment form. Purpose: The purpose of this study was to assess the loading distributing characteristics of 3 implant systems with internal connection under vertical and inclined loading using finite element analysis. Material and method: Three finite element models were designed according to the type of internal connection of ITI(model 1), Friadent(model 2), and Bicon(model 3) respectively. This study simulated loads of 200N in a vertical direction (A), a $15^{\circ}$ inward inclined direction (B), and a $30^{\circ}$ outward inclined direction (C). Result: The following results have been made based on this numeric simulations. 1. The greatest stress showed in the loading condition C of the inclined load with outside point from the centric cusp tip. 2. Without regard to the loading condition, the magnitudes of the stresses taken at the supporting bone, the implant fixture, and the abutment were greater in the order of model 2, model 1, and model 3. 3. Without regard to the loading condition, greater stress was concentrated at the cortical bone contacting the upper part of the implant fixture, and lower stress was taken at the cancellous bone. 4. The stress of the implant fixture was usually widely distributed along the inner surface of the implant fixture contacting the abutment post. 5. The stress distribution pattern of the abutment showed that the great stress was usually concentrated at the neck of the abutment and the abutment post, and the stress was also distributed toward the lower part of the abutment post in case of the loading condition B, C of the inclined load. 6. In case of the loading condition B, C of the inclined load, the maximum von Misess stress at the whole was taken at the implant fixture both in the model 1 and model 2, and at the abutment in the model 3. 7. The stress was inclined to be distributed from abutment post to fixture in case of the internal connection system. Conclusion: The internal connection system of the implant and the abutment connection methods, the stress-induced pattern at the supporting bone, the implant fixture, and the abutment according to the abutment connection form had differenence among them, and the stress distribution pattern usually had a widely distributed tendency along the inner surface of the implant fixture contacting the a butment post.

• The Journal of Advanced Prosthodontics
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• v.11 no.3
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• pp.147-154
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• 2019

PURPOSE. This study aimed to evaluate the effect of two different implant-abutment connection structures with identical implant design on peri-implant bone level. MATERIALS AND METHODS. This clinical study was a patient-blind randomized controlled trial following the CONSORT 2010 checklists. This trial was conducted in 24 patients recruited between March 2013 and July 2015. Implants with internal friction connection were compared to those with external hex connection. One implant for each patient was installed, replacing the second molar. Implant-supported crowns were delivered at four months after implant insertion. Standardized periapical radiographs were taken at prosthesis delivery (baseline), and one year after delivery. On the radiographs, distance from implant shoulder to first bone-to-implant contact (DIB) and peri-implant area were measured, which were the primary and secondary outcome, respectively. RESULTS. Eleven external and eleven internal implants were analyzed. Mean changes of DIB from baseline to 1-year postloading were 0.59 (0.95) mm for the external and 0.01 (0.68) mm for the internal connection. Although no significant differences were found between the two groups, medium effect size was found in DIB between the connections (Cohen's d = 0.67). CONCLUSION. Considering the effect size in DIB, this study suggested the possibility of the internal friction connection structure for more effective preservation of marginal bone.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.2
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• pp.174-184
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• 2006

Purpose: Current trend in implant dentistry is changing from external connection to internal connection. To evaluate the splinting of external and internal connection implant on screw loosening, 2-units prosthesis was fabricated with BioPlant $System^(R)$ of external connection type and Lifecore STAGE-1 Single Stage Implant $System^(R)$ of internal connection type. Material and Method: Experimental group is classified into three groups. 1) $G_1-EE$: 2-units prosthesis was fabricated with two Bioplant $System^(R)$ of external connection type. 2) $G_1-EI$: 2-units prosthesis was fabricated with one BioPlant $System^(R)$ of external connection type and one Lifecore STAGE-1 Single Stage Implant $System^(R)$ of internal connection type. 3) $G_1-II$: 2-units prosthesis was fabricated with two Lifecore STAGE-1 Single Stage Implant $System^(R)$ of internal connection type. In fabricating 2-units prosthesis, two hexed abutments are recommended when two implants are installed parallel, otherwise one hexed abutment is used on major occlusal force area and one nonhexed abutment is used on the other area. Since it is rare to find two implants being parallel, it is hard to fabricate prosthesis with passive adaptation using two hexed abutments. It is much more difficult to acquire passive adaptation when using hex abutment compared to nonhex abutment. To evaluate the influence of hexed and nonhexed abutment on screw loosening, 2-units prosthesis was fabricated with hexed and nonhexed abutment. Experimental group is classified into three groups. 1) $G_2-HH$: 2-units prosthesis was fabricated with two hexed abutments. 2) $G_2-HN$: 2-units prosthesis was fabricated with one hexed abutment and one nonhexed abutment. 3) $G_2-NN$: 2-units prosthesis was fabricated with two nonhexed abutments. Result: The results of comparing the detorque value after loading on a each prosthesis periodically are as follows. 1. In splinting group of external and internal connection implant, $G_1-II$ group demonstrated the biggest detorque value, followed by $G_1-EI$ group and $G_1-EE$ group. 2. There is no notable significance between external connection implant of $G_1-EI$ group and $G_1-EE$ group and also no significance between internal connection implant of $G_1-EI$ group and $G_1-II$ group. 3. $G_2-HH$ group showed higher detorque value than $G_2-HN\;and\;G_2-NN$ group. From the results, we can concluded that using both external connection and internal connection implant together is clinically acceptable and in order to acquire a good passive adaptation in fabricating 2-units implant prosthesis we can use two nonhexed abutments.