Objective: To compare the accuracy and retention of denture bases fabricated by injection molding, milling, and three-dimensional (3D) printing fabricating, in order to provide some references for clinical practice. Methods: A maxillary edentulous jaw model made was used to duplicated 10 working casts. The casts were numbered and scanned. The wax pattern was designed by digital ways and conventional methods and then the denture bases were fabricated by injection molding, milling, and 3D printing. The tissue surface of experimental denture base was obtained using a dental laboratory scanner. The deviation between the tissue surface of the fabricated denture bases and the working model was evaluated. A digital force gauge was used to measure the traction force. Results: The milling group [(0.076±0.026) mm] was more accurate than the 3D printing group [(0.117±0.041) mm] (P<0.05) and the injection group [(0.120± 0.025) mm] (P<0.05). The accuracy of 3D printing group and that of injection group were not statistically significant (P>0.05). The milling group [(9.55±2.44) N] demonstrated greater retentive force than 3D printing group [(5.19±0.06) N] and injection molding group [(1.52±0.52) N] (P<0.05). Conclusions: The denture base fabricated by milling was more accurate and showed the greatest retentive force than the other groups. And 3D printing group showed better retentive force than the injection molding group. Both digital manufacturing methods can meet the requirements of clinical application.
Computer-Aided Design ; Denture Bases ; Humans ; Jaw, Edentulous ; Maxilla ; Printing, Three-Dimensional

In edentulous patient, not only mastication and pronunciation but also esthetics are compromised. By restoring an edentulous patient with complete dentures, masticatory function and esthetics can be rehabilitated. The advantages of the dentures using CAD/CAM are that they can be reconstructed ubiquitously with stored data, and the strength and density of CAD/CAM material are clinically acceptable. In this clinical report, interocclusal record was taken in a conventional manner and then two lab processing procedures were performed: conventional method and CAD/CAM method. Two types of processing procedures were compared and evaluated. Fair clinical results were obtained in both ways, satisfying the patient.
Denture Bases ; Denture, Complete ; Dentures ; Esthetics ; Humans ; Mastication ; Methods

PURPOSE: The accuracy of denture bases was compared among injection molding, milling, and rapid prototyping (RP) fabricating method. MATERIALS AND METHODS: The maxillary edentulous master cast was fabricated and round shaped four notches were formed. The cast was duplicated to ten casts and scanned. In the injection molding method, designed denture bases were milled from a wax block and fabricated using SR Ivocap injection system. Denture bases were milled from a pre-polymerized block in the milling method. In the RP method, denture bases were printed and post-cured. The intaglio surface of the base was scanned and surface matching software was used to measure inaccuracy. Measurements were performed between four notches and two points in the mid-palatal suture to evaluate inaccuracy. The palatine rugae resolution was evaluated. One-way analysis of variance was used for statistical analysis at α=.05. RESULTS: No statistically significant differences in distances among four notches (P>.05). The accuracy of the injection molding method was lower than those of the other methods in two points of the mid-palatal suture significantly (P < .05). The degree of palatine rugae resolution was significantly higher in the injection molding method than that in other methods (P < .05). CONCLUSION: The overall accuracy of the denture base is higher in milling and RP method than the injection molding method. The degree of fine reproducibility is higher in the injection molding method than the milling or RP method.
Denture Bases ; Dentures ; Fungi ; Methods ; Printing, Three-Dimensional ; Sutures

PURPOSE: The purpose of this study was to compare mechanical and physical properties of injection-molded thermoplastic denture base resins. MATERIALS AND METHODS: In this study, six commercially available products (VA; Valplast, LC; Lucitone, ST; Smiltone, ES; Estheshot-Bright, AC; Acrytone, WE; Weldenz) were selected from four types of thermoplastic denture base materials (Polyamide, Polyester, Acrylic resin and Polypropylene). The flexural properties and shore D hardness have been investigated and water sorption and solubility, and color stability have evaluated. RESULTS: For the flexural modulus value, ES showed the highest value and WE showed significantly lower value than all other groups (P < .05). Most of experimental groups showed weak color stability beyond the clinically acceptable range. CONCLUSION: Within the limits of this study, thermoplastic denture base resin did not show sufficient modulus to function as a denture base. In addition, all resins showed discoloration with clinical significance, and especially polyamides showed the lowest color stability.
Denture Bases ; Dentures ; Hardness ; Nylons ; Polyesters ; Solubility ; Water

PURPOSE: This study evaluated the effect of nonthermal plasma treatment on the bond strength of autopolymerizing relining resin to the injection molded thermoplastic denture base resins (TDBRs) with different surface treatments. MATERIALS AND METHODS: Acrylic Resin (Acrytone), Polyester (Estheshot-Bright), Polyamide (Valplast) and Polypropylene (Weldenz) were subjected to various surface treatments: No treatment, Nonthermal plasma, Sandblasting, Sandblasting and nonthermal plasma. Specimens were bonded using an autopolymerizing relining resin. Shear bond strength was tested using universal testing machine with crosshead speed of 1 mm/min. Statistical analysis by two-way analysis of variance with Tukey's test post hoc was used. RESULTS: Acrytone showed significantly higher shear bond strength value among other TDBR group while Weldenz had the lowest. The sandblasting and nonthermal plasma condition had significantly higher shear bond strength value in all of the resin groups (P < .05). CONCLUSION: The use of nonthermal plasma treatment showed limited effect on the shear bond strength between TDBRs and relining resin, and combination of nonthermal plasma and sandblasting improved the shear bond strength between TDBR and reline material.
Denture Bases* ; Dentures* ; Fungi ; Nylons ; Plasma* ; Polyesters ; Polypropylenes

PURPOSE: The aim of this preliminary study was to investigate, for the first time, the effects of addition of titania nanotubes (n-TiO2) to poly methyl methacrylate (PMMA) on mechanical properties of PMMA denture base. MATERIALS AND METHODS: TiO2 nanotubes were prepared using alkaline hydrothermal process. Obtained nanotubes were assessed using FESEM-EDX, XRD, and FT-IR. For 3 experiments of this study (fracture toughness, three-point bending flexural strength, and Vickers microhardness), 135 specimens were prepared according to ISO 20795-1:2013 (n of each experiment=45). For each experiment, PMMA was mixed with 0% (control), 2.5 wt%, and 5 wt% nanotubes. From each TiO2:PMMA ratio, 15 specimens were fabricated for each experiment. Effects of n-TiO2 addition on 3 mechanical properties were assessed using Pearson, ANOVA, and Tukey tests. RESULTS: SEM images of n-TiO2 exhibited the presence of elongated tubular structures. The XRD pattern of synthesized n-TiO2 represented the anatase crystal phase of TiO2. Moderate to very strong significant positive correlations were observed between the concentration of n-TiO2 and each of the 3 physicomechanical properties of PMMA (Pearson's P value ≤.001, correlation coefficient ranging between 0.5 and 0.9). Flexural strength and hardness values of specimens modified with both 2.5 and 5 wt% n-TiO2 were significantly higher than those of control (P≤.001). Fracture toughness of samples reinforced with 5 wt% n-TiO2 (but not those of 2.5% n-TiO2) was higher than control (P=.002). CONCLUSION: Titania nanotubes were successfully introduced for the first time as a means of enhancing the hardness, flexural strength, and fracture toughness of denture base PMMA.
Denture Bases ; Dentures ; Hardness ; Nanotubes ; Polymethyl Methacrylate

PURPOSE: The aim of this study was to evaluate the effects of relining materials on the flexural strength of relined thermoplastic denture base resins (TDBRs). MATERIALS AND METHODS: For shear bond strength testing, 120 specimens were fabricated using four TDBRs (EstheShot-Bright, Acrytone, Valplast, Weldenz) that were bonded with three autopolymerizing denture relining resins (ADRRs: Vertex Self-Curing, Tokuyama Rebase, Ufi Gel Hard) with a bond area of 6.0 mm in diameter and were assigned to each group (n=10). For flexural strength testing, 120 specimens measuring 64.0×10.0×3.3 mm (ISO-1567:1999) were fabricated using four TDBRs and three ADRRs and were assigned to each group (n=10). The thickness of the specimens measured 2.0 mm of TDBR and 1.3 mm of ADRR. Forty specimens using four TDBRs and 30 specimens using ADRRs served as the control. All specimens were tested on a universal testing machine. For statistical analysis, Analysis of variance (ANOVA) with Tukey's test as post hoc and Spearman's correlation coefficient analysis (P=.05) were performed. RESULTS: Acry-Tone showed the highest shear bond strength, while Weldenz demonstrated the lowest bond strength between TDBR and ADRRs compared to other groups. EstheShot-Bright exhibited the highest flexural strength, while Weldenz showed the lowest flexural strength. Relined EstheShot-Bright demonstrated the highest flexural strength and relined Weldenz exhibited the lowest flexural strength (P < .05). Flexural strength of TDBRs (P=.001) and shear bond strength (P=.013) exhibited a positive correlation with the flexural strength of relined TDBRs. CONCLUSION: The flexural strength of relined TDBRs was affected by the flexural strength of the original denture base resins and bond strength between denture base resins and relining materials.
Denture Bases ; Denture Liners ; Denture Rebasing ; Dentures

The purpose of this study was to investigate the effect of retaining holes on the denture base, as well as primer application, on the shear bond strength of denture base resin to the denture base. Using Trubyte Biotone artificial teeth, we selected a maxillary first molar and prepared a total of 80 teeth. Each prepared tooth was polished flat using a dental bar. The polished specimens were placed in the center of a silicon mold (diameter 30 mm, height 23 mm) and were embedded with clear acrylic resin (Ortho Jet, Lang Dental, USA). Forty specimens were shaped, using Fisher bar # 701 at the central part of the alveolar surface, to form retention holes. Each denture base resin was transferred to the resin after surface treatment, as instructed by the manufacturer. The highest shear bond strength (36.2 MPa) was achieved by heat-polymerized resin, when the retention hole and the primer were applied to the artificial tooth. The lowest shear bond strength (11.8 MPa) was achieved by auto-polymerized resin, when the primer was applied to the artificial tooth. The combination of heat-polymerized resin and artificial tooth resulted in a complex fracture pattern, whereas auto-polymerized resin and artificial tooth showed an adhesive fracture pattern.
Adhesives ; Denture Bases ; Dentures ; Fungi ; Molar ; Silicon ; Tooth ; Tooth, Artificial

PURPOSE: The design of the attachment must provide an optimum stress distribution around the implant. In this study, for implant overdentures with a bar/clip attachment or a locator attachment, the stress transmitted to the implant in accordance with the change in the denture base length and the vertical pressure was measured and analyzed. MATERIALS AND METHODS: Test model was created with epoxy resin. The strain gauges made a tight contact with implant surfaces. A universal testing machine was used to exert a vertical pressure on the mandibular implant overdenture and the strain rate of the implants was measured. RESULTS: Means and standard deviations of the maximum micro-deformation rates were determined. 1) Locator attachment: The implants on the working side generally showed higher strain than those on the non-working side. Tensile force was observed on the mesial surface of the implant on the working side, and the compressive force was applied to the buccal surface and on the surfaces of the implant on the non-working side. 2) Bar/clip attachment: The implants on the both non-working and working sides showed high strain; all surfaces except the mesial surface of the implant on the non-working side showed a compressive force. CONCLUSION: To minimize the strain on implants in mandibular implant overdentures, the attachment of the implant should be carefully selected and the denture base should be extended as much as possible.
Denture Bases* ; Denture, Overlay* ; Dentures*

PURPOSE: The purpose of this study is to evaluate the displacement of artificial tooth of monolithic complete denture manufactured by milling and 3D printing method in which the denture base and the artificial teeth are simultaneously made. MATERIALS AND METHODS: Twelve upper and lower complete dentures for each were made by milling and 3D printing method. Group Up and Group Lp are a group of upper and lower dentures made by printing, and Group Um and Group Lm are denture groups made by milling. Group Uc and Group Lc are is a group of finally designed upper and lower dentures respectively. Measurements were performed between both central incisors (AB, ab), both canines (CD, cd), both first molars (EF, ef), between an incisor and a first molar (AE, ae), and between incisor and lingual point (AG, ag) for each upper and lower denture. RESULTS: AG and ag value between printed dentures and original ones as well as between milled dentures and original ones showed a statistically significant difference (One-way ANOVA, P<.05) in both lower and upper monolithic dentures. In the lower monolithic ones, ab, cd and ef value revealed a significant difference between Group Lp and Group Lm (One-way ANOVA, P<.05). CONCLUSION: Dentures made using milling or 3D printers revealed statistically significant difference compared with those of original data. However, it showed clinically very accurate reproducibility.
Denture Bases ; Denture, Complete* ; Dentures ; Incisor ; Methods ; Molar ; Printing, Three-Dimensional* ; Tooth, Artificial*