• 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.

• Journal of Periodontal and Implant Science
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• v.50 no.5
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• pp.340-354
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• 2020

Purpose: This pilot study was conducted to evaluate the cleaning efficacy of an angled implant brush for home oral hygiene of full-arch fixed-implant prostheses. Methods: Forty-one patients treated with a full-arch implant rehabilitation in the maxilla or mandible (164 implants) for at least 4 months were enrolled. The screw-retained fixed prostheses were removed and baseline (T0) parameters were recorded, including plaque index (PI), probing depth (PD), and bleeding on probing (BOP). All patients completed a 5-item questionnaire on hygiene maintenance and received an implant brush for home hygiene. After 1 month (T1) PI, PD, and BOP were recorded again and patients completed a 7-item questionnaire to evaluate their satisfaction with the implant brush. One-way repeated-measures analysis of variance was conducted to evaluate the significance of changes in PI, PD, and BOP. A P value <0.05 was considered to indicate statistical significance. Results: A statistically significant reduction of BOP (0.62±0.6 at T0 vs. 0.5±0.5 at T1; P=0.032) was found, while no statistically significant changes in PD (1.74±0.5 mm at T0 vs. 1.77±0.5 mm at T1; P=0.050) or PI (1.9±0.7 at T0 vs. 1.7±0.7 at T1; P=0.280) occurred. According to the 7-item questionnaire, patients reported no difficulty in using the angled brush (63.4%) and deemed it highly (46.3%) or very highly (4.8%) effective in improving their home oral hygiene. Conclusions: Within the limits of the present pilot study, the patients experienced a reduction of BOP 1 month after being instructed to use the angled implant brush. The angled implant brush appeared to be a well-accepted device for home-care hygiene of full-arch fixed-implant rehabilitations.

• The Journal of the Korean dental association
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• v.58 no.9
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• pp.583-589
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• 2020

If the implant is planted in the wrong position or direction, it is disadvantageous for stress distribution, and it is easy to cause complications such as screw loosening, abutment fracture, and implant fracture. If the position or orientation of the implant is not good, efforts should be made to minimize the problem through proper implant prosthetic treatment. In this article, the prosthetic method for facilitating future maintenance in cases with poor implant placement or orientation will be presented.

• The Journal of Advanced Prosthodontics
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• v.8 no.2
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• pp.131-136
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• 2016

PURPOSE. The aim of this study was to observe stress concentration in the implant, the surrounding bone, and other components under the pull-out force during the crown removal. MATERIALS AND METHODS. Two 3-dimensional models of implant-supported conventional metal ceramic crowns were digitally constructed. One model was designed as a vertically placed implant ($3.7mm{\times}10mm$) with a straight abutment, and the other model was designed as a 30-degree inclined implant ($3.7mm{\times}10mm$) with an angled abutment. A pull-out force of 40 N was applied to the crown. The stress values were calculated within the dental implant, the abutment, the abutment screw, and the surrounding bone. RESULTS. The highest stress concentration was observed at the coronal portion of the straight implant (9.29 MPa). The stress concentrations at the cortical bone were lower than at the implants, and maximum stress concentration in bone structure was 1.73 MPa. At the abutment screws, the stress concentration levels were similiar (3.09 MPa and 3.44 MPa), but the localizations were different. The stress at the angled abutment was higher than the stress at the straight abutment. CONCLUSION. The pull-out force, applied during a crown removal, did not show an evident effect in bone structure. The higher stress concentrations were mostly observed at the implant and the abutment collar. In addition, the abutment screw, which is the weakest part of an implant system, also showed stress concentrations. Implant angulation affected the stress concentration levels and localizations. CLINICAL IMPLICATIONS. These results will help clinicians understand the mechanical behavior of cement-retained implant-supported crowns during crown retrieval.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_2
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• pp.623-628
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• 2023

The purpose of this study was to evaluate the fracture strength and removal torque value (RTV) of a conventional angled abutment and a newly developed angled abutment (Beauty up abutment) with an angulated screw access hole. Each abutment was divided into a control group and an experimental group (n = 20, respectively). To measure the fracture strength, the abutment was connected to the internal hex implant with 30 Ncm torque, and a load was applied at 30 degree angle with cross-head speed of 1 mm/min using a universal testing machine according to the ISO 14801:2016 standard. To measure RTV, each abutment was fastened to the implant with 30 Ncm torque. Retightening was performed after 10 minutes, and initial RTV was measured with a digital torque gauge. After retightening, a load of 250 N was applied to the abutment at a 30 degree angle using a chewing simulator. After a total of 100,000 repeated loads, RTV was measured. Statistical analysis was performed using Wilcoxon signed rank test and Mann-Whitney U test (α = .05). The fracture strength of the experimental group was statistically significantly lower than that of the control group (P = .009). There was no significant difference between initial RTV and post-loading RTV between the experimental group and the control group (P = .753, P = .527, respectively), and cyclic loading did not significantly affect RTV in both groups (P = .078).

• The Journal of Advanced Prosthodontics
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• v.2 no.2
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• pp.58-60
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• 2010

Presurgical prosthetic treatment planning is critical for the success of the implant prosthesis. Inadequate treatment plan, due to insufficient discussion between prosthodontist, and surgeon, may result in poor prognosis. A 26-year-old male patient was referred for prosthodontic treatment after implant was placed in the area of teeth #17,16, 22, 25 and 27, without adequate discussion nor the treatment planning between oral surgeon and prosthodontist. It was found that the patient had two hopeless teeth, and a severely resorbed alveolar ridge. Additional tooth extraction was needed and the type of definitive prosthesis was shifted from fixed type to removable one. Proper pre-surgical treatment planning is essential for the good prognosis. Implant-supported removable prosthesis on milled bars may be a useful treatment option in patients with incorrect angled placement on severely resorbed alveolar ridge.

• The Journal of Advanced Prosthodontics
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• v.15 no.4
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• pp.179-188
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• 2023

PURPOSE. This in vitro study aimed to evaluate the performance of digital intraoral scanners in a completely edentulous patient with angled and parallel implants. MATERIALS AND METHODS. A total of 6 implants were placed at angulations of 0°, 5°, 0°, 0°, 15°, and 0° in regions #36, #34, #32, #42, #44, and #46, respectively, in a completely edentulous mandibular polyurethane model. Then, the study model created by connecting a scan body on the implants was scanned using a model scanner, and a 3D reference model was obtained. Three different intraoral scanners were used for digital impressions (PS group, TR group, and CS group, n = 10 in each group). The distances and angles between the scan bodies in these measurement groups were measured. RESULTS. While the Primescan (PS) impression group had the highest accuracy with 38 ㎛, the values of 104 ㎛ and 171 ㎛ were obtained with Trios 4 IOSs (TR) and Carestream 3600 (CS), respectively (P = .001). The CS scanner constituted the impression group with the highest deviation in terms of accuracy. In terms of dimensional differences in the angle parameter, a statistically significant difference was revealed among the mean deviation angle values according to the scanners (P < .001). While the lowest angular deviation was obtained with the PS impression group with 0.185°, the values of 0.499° and 1.250° were obtained with TR and CS, respectively. No statistically significant difference was detected among the impression groups in terms of precision values (P > .05). CONCLUSION. A statistically significant difference was found among the three digital impression groups upon comparing the impression accuracy. Implant angulation affected the impression accuracy of the digital impression groups. The most accurate impressions in terms of both distance and angle deviation were obtained with the PS impression group.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.349-360
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• 2009

Purpose: As the esthetic demands of dental implant patients are increased, the demands of zirconia as implant abutment material are also increased. It has non-metalic color, good biocompatibility, high strength and high toughness. Even thought the advatage of zirconia abutment, there are a few studies about mechanical properties of zirconia abutment. This study evaluated the mecanical strength with compressive bending strength and endurance limit of implant-zirconia abutment assembly. Materials and Methods: Static and cyclic loading of implant-Zirconia abutment assembly were simulated under worst case condition according to ISO. Test groups were implants of external butt joint with straight regular diameter and angled regular diameter zirconia abutment, implant of external butt joint with narrow straight diameter zirconia abutment and implant of internal conical joint with straight narrow diameter zirconia abutment. All test group were evaluated the mecanical strength with compressive bending strength and endurance limit. After fatique testing, fracture surface were examined by SEM. Results: The compressive bending strengths exceed 927N. Regular diameter zirconia abutment were stronger than narrow diameter zirconia abutment(P<.05). The endurance limits ranged from 503N to 868N. Conclusion: Within the limitation of this study, zirconia implant abutment exceeded the estabilished values for maximum incisal biting forces reported in the literature.

• The Journal of the Korean dental association
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• v.54 no.3
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• pp.191-197
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• 2016

In the past, restoration of implant crown, ready-made abutment produced by implant manufacturer could only be used. Using straight, angled abutment, there was a limit in adaptation multiple implants. Recently, with the development of implant and CAD/CAM technology, CAD/CAM customized abutment use has become possible which is different from the past when restoration was possible with only prefabricated abutment. Not only it makes emergence profile possible which is similar to natural teeth, but also it makes insertion path possible on CAD in multiple implant restorations. However, on anterior teeth which dental esthetics is very important, another restorations which are formed with natural colored gingiva area could be required. Titanium-based zirconia prostheses which have titanium connection and zirconia structure from 1mm above fixture platform are alternative. Therefore, the purpose of this review is to analyze the characteristics, advantages and disadvantages of the abutment which is used in multiple implant restorations, and to choose right abutment when clinical trials.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.4
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• pp.679-686
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• 1993

The osseointegrated implant conducts the stress directly to the bone due to lack of cushoning effect of periodontal ligament. So, the design and material quality of superstructure plays an important role in resolution and diffusion of stress. Recently, the various superstructures have been developed to improve esthetics and resolve various complicated conditions. The purpose of this study was to evaluate the stress induced by various system on the osseointegrated implant using UCLA abutment, EsthetiCone abutment, Anatomic abutment as well as Branemark conventional abutment. The stress distribution was evaluated by the photoelastic method which can simultaneously observe all around stress distribution. The superstructures embedded in epoxy resin specimen were loaded at various angle with a force of 15Kg to analyse the stress distribution of the fixture. The results of this study were obtained as follows : 1. Under vertical loading, the large and broad stress was distributed below the fixture in all systems. 2. The fringe order of the stress was increased in proportion to tillting the specimen. The largest stress was shown in 25 angled degree tilting case. 3. The Branemark conventional abutment showed the lowest value, and EsthetiCone abutment, Anatomic abutment and UCLA abutment showed the stress value in accending order.