Publications by authors named "JaiYoung Koak"
Article Synopsis
- A study was conducted to examine the accuracy and failure load of 3D printed interim fixed dental prostheses (FDPs) with different wall thicknesses in their hollow pontic designs, focusing on how inward polymerization shrinkage affects fit.
- The investigation involved creating multiple 3D printed specimens with varying wall thicknesses (4 options: solid and 2.5, 2.0, and 1.5 mm) and measuring their fit and strength using advanced imaging and testing techniques.
- Results showed that the 2.0-mm wall thickness provided a better fit and comparable strength to solid designs, while thinner walls led to increased fracture rates, highlighting the importance of wall thickness in prosthetic design.
Article Synopsis
- 3D printed zirconia materials are compared to milled zirconia, particularly focusing on their flexural strength, with previous studies mostly examining 3Y-TZP, prompting the need for research on 4Y-TZP.
- This study evaluated the flexural strength of four types of zirconia specimens (two 3D printed and two milled) using a standardized testing method and analyzed their crystalline structure through various methods.
- Results indicated that 3D printed 4Y-TZP had significantly higher flexural strength than milled 4Y-TZP, while 3D printed 3Y-TZP exhibited lower strength compared to its milled counterpart, with tetragonal phases confirmed in all
Article Synopsis
- The study focused on how fixed implants in toothless areas affect oral health-related quality of life (OHRQoL) in disabled patients, highlighting the lack of research in this area.
- Using the OHIP-14 questionnaires, researchers evaluated 63 disabled individuals and found significant improvements in OHRQoL scores after implant treatment.
- Results indicated that while severity of disability impacted OHRQoL improvements, older patients exhibited lower scores post-treatment, with no significant differences found based on sex or whether the disability was congenital or acquired.
Comparison of Fit and Stability Between 3D-Printed and Milled Implant Abutments with Titanium-6Al-4V and Co-Cr Metal Alloys.
Int J Oral Maxillofac Implants
October 2023
Article Synopsis
- - The study compared the fit and clinical performance of 3D-printed titanium (Ti) and cobalt-chromium (Co-Cr) abutments with traditional CNC-milled abutments using parameters like removal torque values (RTVs).
- - A total of 138 abutments were examined, with various techniques like scanning electron microscopy (SEM) used to assess the fit, and the impact of torque tightening and cyclic loading on the RTVs was measured.
- - Results indicated that 3D-printed Co-Cr abutments fit well with implants, showing comparable RTVs to CNC-milled ones, whereas the fit of 3D-printed Ti abutments was found to be inadequate. *
Could Fixed Implants Be a Viable Treatment Option in Disabled Patients? A Clinical Retrospective Study.
Int J Oral Maxillofac Implants
October 2023
Article Synopsis
- * The results showed a high overall implant survival rate of 97.8%, but notable differences in cumulative survival rates based on disability type, with mental disability patients having a rate of 94.3% and physical disability patients at only 50%.
- * The findings suggest that while dental implants are a viable option for patients with disabilities, mental disability patients experienced higher survival rates but also more MBL compared to those with physical disabilities, indicating the need for tailored treatment plans.
Article Synopsis
- The study analyzed 888 implants from 423 patients over 15 years to evaluate the success and survival rates of splinted versus nonsplinted implants.
- The cumulative success rate was 34.2%, with no significant difference between splinted (34.8%) and nonsplinted (33.2%) implants; however, the survival rate was high at 92.9%.
- Key factors affecting implant success included smaller implant diameter lowering survival rates, and for nonsplinted implants, longer crown lengths and shorter implant lengths increased the risk of failure, while certain emergence angles and profiles impacted the risk in splinted implants.
Purpose: To analyze the biologic and mechanical complications of splinted and nonsplinted implant restorations.
Materials And Methods: A total of 423 patients (n = implants: 888) were included in the study. Biologic and mechanical complications that occurred for 15 years were analyzed using the multivariable Cox regression model, and the significant effect of the splinting of prostheses and other risk factors were evaluated.
Article Synopsis
- The study aimed to evaluate how hemispherical dimple structures affect the retention of cobalt-chromium (Co-Cr) crowns on titanium abutments with varying heights and dimple configurations.
- Researchers prepared 180 different crown and abutment setups, using two different cements, and measured retention forces after thermal treatments.
- Results indicated that dimples significantly improved retention force compared to control groups, and higher 6.0-mm abutments yielded better retention than 3.0-mm ones, with less adhesive failure noted in dimpled groups.
Article Synopsis
- Printing conditions significantly influence the fit of SLA 3D printed prostheses, making it essential to find optimal settings for layer thickness and build orientation.
- The study evaluated 5 different build orientations and 2 layer thicknesses to analyze their effects on the fit of 3-unit resin prostheses using advanced imaging and statistical methods.
- Results indicated that a layer thickness of 50 μm paired with orientations of 45 and 60 degrees led to better fit measurements compared to other configurations, while both 3D printed and milled prostheses had acceptable fit outcomes.
Purpose: To retrospectively analyze the success of implant-assisted removable partial dentures (IARPDs) according to three types of strategic positions in distal extension areas of Kennedy Class I and II arches.
Materials And Methods: The data included 102 arches in 95 patients with Kennedy Class I/II arches treated with IARPDs with implants in three strategic positions: Type 1a, assisted by P-1a implants on the anterior area adjacent to the abutment tooth; Type 1b, assisted by P-1b implants on the anterior area apart from the abutment tooth with or without P-1a; Type 2, assisted by P-2a implants on the posterior area adjacent to the natural tooth or P-2b implants on the posterior area apart from the abutment tooth to modify from Kennedy Class I /II to Class III. The success was defined as the IARPDs without abutment tooth-related, denture-related, and implant-related complications.
Article Synopsis
- - The study aimed to evaluate how the build orientation (45° vs. 60°) and layer thickness (50 µm vs. 100 µm) impact the fit of three-unit resin prostheses created through stereolithography (SLA) printing.
- - Forty resin specimens were produced, and their fit was measured at various points, revealing that the fit was generally better at a 45° angle compared to a 60° angle, while layer thickness did not significantly influence fit.
- - The findings suggest that the area near the pontic had the largest gaps, emphasizing the importance of build orientation in achieving better overall fit, with a 45° orientation being the preferred choice.
Purpose: To compare the clinical outcomes of two types of implant restoration for posterior edentulous area, 3-unit bridge supported by 2 implants and 3 implant-supported splinted crowns.
Materials And Methods: The data included 127 implant-supported fixed restorations in 85 patients: 37 restorations of 3-unit bridge supported by 2 implants (2-IB), 37 restorations of 3 implant-supported splinted crowns (3-IC), and 53 single restorations (S) as controls. Peri-implantitis and mechanical complications that occurred for 14 years were analyzed by multivariable Cox regression model.
Purpose: The purpose of this study was to evaluate survival rates and marginal bone loss (MBL) of implants in IC-RPDs.
Materials And Methods: Seventy implants were placed and used as surveyed crowns in 30 RPDs. The survival rates and MBL around implants based on multiple variables, e.
Article Synopsis
- Internal conical connections are commonly used for implant-supported restorations, but there's limited research on the mechanical complications associated with them.
- This study examined 898 internal conical connection implants in 428 patients over 14 years, focusing on the occurrence and consequences of mechanical complications.
- Findings revealed a high incidence of issues like screw loosening and fractures, with molar restorations being at the greatest risk, and factors such as gender and type of screw influencing complication rates.
The studies on implant-crown-retained removable partial dentures (IC-RPDs) for edentulism are scarce. The purpose of this study was to evaluate survival rates and marginal bone loss (MBL) of IC-RPDs compared to implant overdentures (IODs) in mandibular edentulism. Variables that influenced survival and marginal bone loss (MBL) of implants in both treatment modalities were analyzed and the functional/esthetic satisfaction of patients as well as prosthetic complications were also observed.
View Article and Find Full Text PDFArticle Synopsis
- This study compared the effectiveness of implant-crown-retained removable partial dentures (IC-RPD) and implant overdentures (IOD) for maxillary edentulous patients, focusing on implant survival rates and marginal bone loss (MBL).
- After observing 20 IC-RPDs and 18 IODs over a median of 47.1 months, IC-RPD showed a significantly higher implant survival rate at 97.3% compared to 70.4% for IOD.
- Both treatments improved patient satisfaction in terms of function and aesthetics, but IOD resulted in more frequent prosthetic complications and higher MBL, especially in older patients and those with peri-implantitis.
Article Synopsis
- This study aims to assess the dimensional accuracy of 3D-printed dental models specifically for three-unit fixed prostheses, focusing on crucial areas like margins and proximal contacts.
- The researchers compared the accuracy of models made using three different printing techniques: Digital Light Processing (DLP), Multi-Jet Printing (MJP), and Stereolithography Apparatus (SLA), and found that MJP provided significantly better accuracy for certain measurements.
- All printing methods resulted in 3D models within clinically acceptable accuracy for dental prosthesis manufacturing, with MJP also demonstrating the least surface roughness among the techniques tested.
Article Synopsis
- Cobalt-chromium (Co-Cr) metal is commonly used in dental prosthesis, and this study evaluated how different manufacturing methods (casting, milling, and selective laser melting) affect its properties and bond strength with ceramics.
- The results showed that casting had the highest elastic modulus and bond strength, while milling had the lowest yield and flexural strength; SLM produced a finer microstructure.
- All manufacturing methods met international bond strength standards, suggesting that SLM could be a viable alternative to traditional methods for creating dental prosthetics.*
Article Synopsis
- This study examines the effectiveness of two bonding agents in enhancing the bond strength between ceramics and Co-Cr metal made using selective laser melting (SLM).
- Bond strength was evaluated through a three-point bending test, with microscopic analysis employed to assess the metal-ceramic interface and the remaining ceramic material after testing.
- Findings indicate that Co-Cr specimens treated with bonding agents displayed significantly greater bond strength and retained more ceramic material compared to those without bonding agents, with variations in surface composition observed based on fabrication methods.
Dimensional accuracy and surface characteristics of 3D-printed dental casts.
J Prosthet Dent
September 2021
Article Synopsis
- A study was conducted to compare the accuracy of dental casts made with different 3D printing methods, focusing on how they distort across a complete arch.
- Five printing techniques were tested: FDM, DLP, Polyjet, and SLA, with evaluations measuring deviations from a computer-aided design (CAD) reference cast using a set of cylinders and spheres for accuracy.
- The results showed that FDM exhibited more inaccuracies compared to other methods, with specific patterns of distortion in different axes and varying surface qualities among the prints.
Article Synopsis
- * It compares the flexural strength of 3D-printed three-unit fixed dental prostheses made using DLP and SLA printing technologies with conventional methods.
- * Results reveal that both DLP and SLA groups have significantly higher flexural strength compared to conventional methods, while the FDM group showed only dents, indicating that DLP and SLA are preferable for temporary dental restorations.
Article Synopsis
- The study aimed to assess how well implants used in implant-assisted removable partial dentures (IARPDs) survive over time.
- It involved 21 patients and evaluated 58 implants over an average follow-up of about 48 months, considering various factors affecting survival rates.
- The overall survival rate for the implants was 93.1%, with slightly higher rates for those supporting surveyed crowns (95.1%) compared to those used in overdentures (88.2%).
The Influence of a Positioning Hex on Abutment Rotation in Tapered Internal Implants: A 3D Finite Element Model Study.
Int J Oral Maxillofac Implants
August 2020
Purpose: The purpose of this study was to investigate the resistance against rotation of a two-piece abutment with or without the presence of a positioning hex in tapered internal connection implant systems.
Materials And Methods: A tapered internal connection implant with an 11-degree internal oblique angle was placed into a constructed three-dimensional (3D) bone model. Two types of abutments were compared: hex-type abutments with a positioning hex and two-piece round-type nonhex abutments.
Managing fractures of implant abutment screws is challenging because of the uncertainty associated with the removal of the fractured screw fragments. In case of unsuccessful retrieval of the fractured fragment with known techniques, removal and replacement of the implant becomes traumatic and financially burdensome to the patient. This clinical report describes a conservative solution for the management of nonretrievable fractured screws by reconnecting the prostheses to the existing implants by using cut screws.
View Article and Find Full Text PDFPurpose: The purpose of this study was to compare computer-aided design/computer-aided manufacturing (CAD/CAM) abutment and prefabricated abutment in Morse taper internal connection type implants after cyclic loading.
Materials And Methods: The study was conducted with internal type implants of two different manufacturers (Group Os, De). Fourteen assemblies were prepared for each manufacturer group and divided into 2 groups (n=7): prefabricated abutments (Os-P, De-P) and CAD/CAM abutments (Os-C, De-C).