Publications by authors named "Lee-Ra Cho"
Background: For restorative demands, increased vertical dimension of occlusion (VDO) is sometimes necessary, as facial changes can be perceptible.
Objectives: This study aimed to evaluate the perception of facial change due to increased VDO and associated soft tissue changes using 3D-scanned facial images.
Methods: Forty participants with healthy dentition and no loss of VDO were recruited.
Purpose: This study aimed to compare the accuracy of an alternative scan path with that of traditional scan paths to obtain a more accurate method for complete arch scans.
Materials And Methods: A mandibular stone cast, including tooth preparations for the inlay, crown, and fixed prosthesis, was scanned 10 times using four different scan paths (A, B, C, and D). The scans were converted into stereolithography files, resized, and superimposed onto a control file obtained from a desktop scanner.
Purpose: This study aimed to investigate the effect of crystallization and finish line curvature on the integrity of lithium disilicate crowns fabricated by using partially crystallized (P) and fully crystallized (F) blocks.
Materials And Methods: Forty-eight lithium disilicate crowns were fabricated based on the designated lithium disilicate blocks and finish line curvatures. The specimens were divided into four groups (n = 12 each): P block with a curved finish line (PC), P block with a straight finish line (PS), F block with a curved finish line (FC), and F block with a straight finish line (FS).
Objectives: To evaluate the complementary mechanical properties of dental ceramics using edge chipping resistance (Rea) and flexural strength before and after thermomechanical aging.
Material And Methods: Computer-aided design and computer-aided manufacturing of ceramic materials, including zirconia (ZR), lithium disilicate (LS2), and resin nanoceramics (RNC), were evaluated. Specimens for flexural strength testing were fabricated with dimensions of 3 × 4 × 25 mm, with 30 specimens per group.
Effect of Occlusal and Axial Thickness on the Fracture Load of Implant-Supported Monolithic Zirconia Crowns.
Int J Oral Maxillofac Implants
October 2024
Purpose: To evaluate the fracture load of monolithic zirconia crowns with implant screw holes, focusing on variations in occlusal and axial thicknesses, and to assess the interaction between these variables.
Materials And Methods: Six different prostheses were designed using CAD software, varying in occlusal thickness (0.5 mm, 1.
Purpose: Bilayered restorations have both the strength of the substructure material and the esthetics of the veneer material; however, they should have appropriate bonding between the two materials. This study aimed to evaluate the shear bond strength (SBS) according to the substructure material and veneering technique used in bilayered restorations.
Materials And Methods: The experimental group was divided into four groups (n = 15 per group) based on the substructure materials (cobalt-chromium [Co-Cr] alloy and 3 mol% yttrium-stabilized tetragonal zirconia polycrystal [3Y-TZP]) and veneering techniques (pressing and layering).
Mandibular condyle fracture malunion and tooth loss can cause functional and esthetic problems. A patient with restricted mouth opening associated with muscle atrophy required prosthetic rehabilitation. Since the remaining teeth had a poor prognosis and the patient had difficulty adapting to the interim denture, complete mouth rehabilitation with implants was chosen.
View Article and Find Full Text PDFChewing Side Preference Related to Food Texture and Occlusal Contact Area.
Int J Prosthodont
September 2024
Purpose: To determine whether food texture affects chewing side preference (CSP) and to investigate the relationship between CSP and masticatory factors, such as occlusal contact area, bite force, and masticatory performance.
Materials And Methods: Forty-seven adults (20 women and 27 men; mean age: 24 years) participated in this study. Three types of food (chewing gum, beef jerky, and peanuts) were provided to assess CSP.
Purpose: The aim of this study was to classify the shapes of retromolar pads and assess their morphometric differences using a 3D model.
Materials And Methods: Two hundred fully edentulous or Kennedy Class I partially edentulous patients (400 retromolar pads) were enrolled. Scan data of the definitive mandibular casts produced through functional impressions were obtained using a 3D laser scanner.
Purpose: The purpose of this in vitro study was to compare the tensile bond strength (TBS) of resin nanoceramics (RNC), zirconia, and lithium disilicate (LS2) restorations cemented to titanium abutments before and after thermomechanical aging.
Materials And Methods: Twelve specimens per group were fabricated to determine the TBS between a titanium abutment and four types of crown materials (2 RNCs, LS2, and translucent zirconia crowns for the maxillary molar). After milling, the abutments and crowns were cemented with resin cement after air-particle abrasion.
Objective: This in vitro study aimed to evaluate the flexural strength (FS) and translucency parameter (TP) of resin nanoceramics (RNCs) with barium silicate for additive manufacturing.
Materials And Methods: An RNC slurry was prepared by mixing a barium silicate filler and resin monomer. For the FS tests, specimens with three filler contents (0, 50, and 63 wt%) were designed according to ISO6872 for dental ceramics and ISO10477 for dental polymers.
Purpose: The mechanical and physical properties of implant screw access opening deteriorate if composite resin is not polymerized properly. Therefore, this study aimed to analyze the effect of using composite resin in implant access opening on the degree of conversion (DC).
Materials And Methods: Two prosthetic materials (Co-Cr and zirconia), two types of composite resin (low and high viscosity), two light-cured resin depths (2 and 3 mm), and two polymerization methods (max-mode 10 s and mid-mode 20 s: 16 and 22 J/cm , respectively) were considered (n = 192).
Purpose: The purpose of this study was to investigate the effect of barium silicate filler contents on mechanical properties of resin nanoceramics (RNCs) for additive manufacturing (AM).
Materials And Methods: Additively manufactured RNC specimens were divided into 4 groups depending on the content of ceramic fillers and polymers: 0% barium silicate and 100% polymer (B0/P10, control group); 50% barium silicate and 50% polymer (B5/P5); 60% barium silicate and 40% polymer (B6/P4); 67% barium silicate and 33% polymer (B6.7/P3.
Statement Of Problem: Studies that compared the fracture strength of monolithic lithium disilicate and 5-mol% yttria partially stabilized zirconia multiunit fixed dental prostheses are sparse.
Purpose: As the connector is the weakest part of a fixed dental prosthesis, the purpose of this in vitro study was to investigate the effect of connector designs and material on the fracture strength of 3-unit monolithic fixed dental prostheses.
Material And Methods: Resin-ceramic canine and premolar teeth (N=144) were prepared for fixed dental prosthesis abutments.
Statement Of Problem: Lithium disilicate and 5 mol% yttria partially stabilized zirconia (5Y-PSZ) are commonly used for anterior restorations. However, studies comparing the durability of 5Y-PSZ and lithium disilicates are sparse.
Purpose: The purpose of this in vitro study was to investigate the fracture load of anterior monolithic crowns made of 2 lithium disilicates and a 5Y-PSZ under dynamic loading.
The mechanical properties and residual stress of dental Co-Cr-Mo (CCM) alloy depend on the manufacturing and post-processing methods, which affect the prognosis of dental prostheses. Two CCM alloys manufactured by casting and selective laser melting (SLM) were compared, and the effect of heat treatment temperature for CCM alloys manufactured by SLM method was evaluated. Specimens were fabricated by casting (Cast Co-Cr) and SLM (SLM Co-Cr).
View Article and Find Full Text PDFInitial Change in the Occlusal Force and Occlusal Contact Area Following Single Molar Implant Restoration.
Int J Oral Maxillofac Implants
December 2021
Purpose: The occlusal force and occlusal contact area may be used to evaluate oral function following restoration of a missing tooth. This study aimed to monitor the initial changes in these factors after single molar implant restoration.
Materials And Methods: Patients who underwent single implant restoration between December 2018 and September 2019 were recruited for this study.
Background: This study aimed to determine the correlation between occlusal contact area and masticatory performance using BiteEye , a photo occlusal analysis device and the multiple sieve method.
Objectives: To calculate the occlusal contact area at various levels of interocclusal thicknesses and to measure masticatory performance with peanuts as the test material.
Methods: Fifty-two adults (30 men and 22 women) were enrolled according to specific exclusion/inclusion criteria.
Purpose: To evaluate the effect of composite cement components and thermocycling on the bond strength of monolithic lithium-disilicate (LS2) glass-ceramic implant-supported restorations bonded to titanium (Ti) abutments.
Materials And Methods: Eighty LS2 blocks were treated with five types of composite cement and primer, then divided accordingly into groups: M (Multilink hybrid abutment), G (G-CEM LinkAce), GP (G-CEM LinkAce with G-Multi PRIMER), P (Panavia F2.0), and U (RelyX U200).
Purpose: The aim of this study is to compare the hardness according to the conditions of metal alloys. Moreover, the correlation between the cast crown hardness before and after wear testing and the degree of wear for each dental alloy was assessed.
Materials And Methods: Cast crowns of three metal alloys (Co-Cr, gold, and Ni-Cr alloys) opposing smooth-surface monolithic zirconia were used.
Statement Of Problem: Materials have been developed to reduce the chipping of ceramic veneer and improve the esthetics of anterior ceramic veneered restorations. However, studies of the effects of material and substructure design on fracture resistance are sparse.
Purpose: The purpose of this in vitro study was to investigate the fracture resistance of metal-ceramic (MC), zirconia-feldspathic porcelain (ZC), and zirconia-lithium disilicate (ZL) anterior restorations and evaluate the effect of material and substructure design.
Statement Of Problem: How axial displacement may be affected by the mechanical properties and internal discrepancy of a cement-retained implant-supported prosthesis is unclear.
Purpose: The purpose of this in vitro study was to assess the difference in internal discrepancy and axial displacement according to the prosthesis material in cement-retained prostheses splinting nonparallel implants.
Material And Methods: Computer-aided design and computer-aided manufacture (CAD-CAM) titanium abutments were fabricated for a vertically placed implant and a 15-degree tilted implant.
Purpose: The effect of core design on the fracture resistance of zirconia-lithium disilicate (LS2) bilayered crowns for anterior teeth is evaluated by comparing with that of metal-ceramic crowns.
Materials And Methods: Forty customized titanium abutments for maxillary central incisor were prepared. Each group of 10 units was constructed using the same veneer form of designs A and B, which covered labial surface to approximately one third of the incisal and cervical palatal surface, respectively.
Purpose: To determine the effects of the total thickness and core/veneer thickness ratio of bilayered ceramics on their three-point flexural strength and translucency.
Materials And Methods: Two groups of specimens were prepared with two different total thicknesses, 1.0 mm and 0.