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Aim: Current CAD/CAM techniques allow clinicians to design and 3D print tooth reduction guides that facilitate controlled preparations in the esthetic zone. The present case report describes the workflow for designing and printing a tooth reduction guide intended to assist ceramic veneer preparations. This 3D-printed guide divides the facial surface of the teeth into four areas and allows the measuring of all areas, including the incisal edge, with a periodontal probe. Using this 3D-printed appliance can simplify and expedite tooth preparation for ceramic veneers and reduce the risk of excessive tooth reduction. Clinical considerations: A 45-year-old female patient presented at the clinic with the primary concern of the esthetics of her smile, which she wanted to improve. The initial evaluation revealed clinical signs of wear, spaces between the teeth, and the lack of anterior tooth symmetry. Therefore, to improve the appearance of her anterior teeth, a treatment plan that consisted of veneer restorations from the maxillary right second premolar to the left second premolar was formulated and presented. The patient accepted the option of undergoing minimally invasive anterior tooth preparations with a digital tooth reduction guide. Materials and methods: A diagnostic intraoral scan was performed and a tooth reduction guide was digitally designed and 3D printed. Subsequently, the tooth preparations were performed with the aid of the guide. An intraoral scan of the preparations was performed and used to design and manufacture lithium disilicate ceramic veneers using subtractive techniques. Subsequently, the restorations were finished, treated, and cemented under rubber dam isolation. Conclusions: The treatment fulfilled the patient's esthetic demands. This novel 3D-printed tooth reduction guide permits a more comprehensive assessment of the available tooth structure and provides ample access to more tooth surfaces than traditional silicone tooth reduction guides. Overall, this type of guide can significantly assist clinicians in performing tooth preparations in the esthetic zone. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate the color stability of bulk-fill flowable resin composites with 2 difference shades at baseline and after artificial aging. Methods: Disk-shaped specimens (Ø10 × 4 mm) were fabricated from three bulk-fill flowable resin resin composites (Filtek Bulk-Fill Flow, Venus Bulk-Fill Flow, and Estelite Bulk-Fill Flow). The specimens in each bulk-fill resin composite group were divided into two subgroups (n = 10 per subgroup) with two different shades, A1 (N = 30) and A3 (N = 30), and were polymerized with light curing (800 mW/cm2/Valo LED Unit, Ultradent) and polished. The color difference between bulk-fill resin composites was evaluated at baseline and after artificial aging using a spectrophotometer (CM-700d, Konica Minolta, Tokyo, Japan) under D65 illumination. Color coordinates were measured with CIEDE2000, and color differences (∆E00) and relative translucency parameter (RTP) values were calculated. Subsequently, the comparison of color changes (∆E00) before and after thermocycling was performed using the t-test for paired samples. Results: The bulk-fill flow resin composites evaluated in the present study were capable of mimicking important optical properties such as light transmission. All the resin composites provided acceptable color stability at baseline and after thermocycling when the color A1 was used. On the other hand, whenever the shade A3 was used, the Venus Bulk-Fill Flow demonstrated the best optical properties. There was no statistically significant difference when comparing baseline and after thermocycling in bulk-fill flowable resin composites (p > 0.05). After thermocycling, A1 bulk-fill flowable resin composites provided acceptable color stability, and all A3 bulk-fill flowable resin composites provided visible color change, except for the Venus Bulk-Fill Flow (∆E00 = 2.35). Conclusions: Estelite Bulk-Fill Flow displayed the best color stability (∆E00 = 2.22) between all the combinations evaluated. [ABSTRACT FROM AUTHOR]

Mandibular flexure is a phenomenon generated by the action of the muscles of mastication and other muscles in the head and neck region which can lead to prosthetic and biological complications such as pain, material fracture, and bone loss around dental implants. To avoid such complications, dividing the mandibular prostheses into 3 short-span prostheses or sectioning at the midline has been suggested. This clinical report presents the management of an edentulous patient with clinically detectable mandibular flexure treated with a 1-piece metal-free complete arch implant-supported prosthesis. [ABSTRACT FROM AUTHOR]

Purpose: To determine the fracture resistance of chairside computer‐aided design and computer‐aided manufacturing (CAD‐CAM) zirconia surveyed crowns for a mandibular first molar without occlusal rest and with four different rest seat designs. Materials and Methods: Seventy CAD‐CAM zirconia 4Y‐PSZ (IPS e.max ZirCAD MT for CEREC A1, C15, Ivoclar Vivadent) crowns (14 specimens/group) were designed and fabricated with a dental chairside CAD‐CAM system (CEREC PrimeScan, and CEREC MCXL Dentsply Sirona). The restorations were divided into groups according to the following rest seat designs: (1) Surveyed crown without rest seat, (2) surveyed crowns with disto‐occlusal rest seat, (3) surveyed crowns with disto‐occlusal extended rest seat, (4) surveyed crowns with interproximal rest seat, and (5) continuous rest seat. Crowns were treated with a primer system (Monobond Plus, Ivoclar Vivadent) and cemented using resin luting cement (Multilink Automix, Ivoclar Vivadent) to resin‐printed dies (Grey Resin V4, FormLabs). Subsequently, the crowns were subjected to 200,000 load cycles at 1 Hz with 20 N force and then loaded with a steel indenter until fracture. The test results were analyzed with one‐way Analysis of Variance (ANOVA) and HSD Tukey post‐Hoc test. Results: The mean fracture resistance of surveyed crowns without and with different rest seats was significantly different from each other. Surveyed crowns with no rest seat displayed the highest resistance (4238 N) followed by crowns with continuous rest seat (3601 N), crowns with disto‐occlusal extended rest seat (3283 N), and crowns with disto‐occlusal rest seat (3257 N). Crowns with interproximal rest seat displayed the lowest fracture resistance (2723 N). Conclusions: Surveyed crowns without rest seats had a higher fracture resistance than crowns with rest seats Surveyed crowns with interproximal rest seats presented the lowest fracture resistance among all rest seat designs. Crowns with disto‐occlusal rest seats, disto‐occlusal extended rest seats, and continuous rest seats displayed similar fracture resistance. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of heated and room-temperature hydrofluoric (HF) acid on surface roughness parameters (Ra and Rq) and microtensile bond strength (µTBS) on feldspathic ceramic and lithium-disilicate glass-ceramics. Materials and Methods: Disk-shaped samples made from both ceramics were divided into groups according to surface treatment: feldspathic ceramic polished surface (FP), feldspathic ceramic + 60 s of 9% HF acid etching at room temperature (FC), feldspathic ceramic + 60 s of 9% HF acid etching heated to 70°C (F70), lithium-disilicate polished surface only (LP), lithium disilicate + 20 s of 9% HF acid etching at room temperature (LC), and lithium disilicate + 20 s of 9% HF acid etching heated to 70°C (L70). To evaluate Ra and Rq, non-overlapping readings were taken on the surface of each sample with a contact stylus profilometer. To measure microtensile bond strength (µTBS), samples of groups FC, F70, LC and L70 received their corresponding surface treatment, were silanized and then bonded using a dual-cure composite cement to resin composite disks. After 24 h, samples were sectioned to obtain specimens for µTBS. Representative samples from each group were examined using scanning electron microscopy (SEM) to analyze the morphology of the etched surface. The data were analyzed for statistical significance using Welch's ANOVA with the Games-Howell multiple-comparison post-hoc test. Results: For both surface roughness parameters and HF acid etching at room temperature (FC and LC) showed a significant increase (p < 0.001) in surface roughness when compared to polished surfaces (FP and LP). Furthermore, the use of heated HF acid etching significantly increased (p < 0.001) the surface roughness of the ceramic when compared to their counterpart sample of HF acid etching at room temperature. Group L70 obtained the highest µTBS of all groups (29.11 ± 8.26 MPa) and was significantly higher (p < 0.001) than that of the other experimental groups. There were no statistical differences (p > 0.05) between groups FC (19.94 ± 4.14), F70 (18.24 ± 5.29), and LC (17.87 ± 6.96). Conclusion: The use of 9% HF acid etching heated to 70°C resulted in significantly higher surface roughness and improved bond strength onto lithium-disilicate glass-ceramic compared to surface HF acid etching at room temperature. [ABSTRACT FROM AUTHOR]

Purpose: The present study evaluated the contact angles (CAs) of four denture base materials subjected to different surface treatments using deionized water and saliva substitutes., Material and Methods: A total of 32 rectangular specimens were manufactured using four different denture base materials: heat-cured compression molded Lucitone 199 (C), milled Lucitone 199 (M), Formlabs Denture Base RP (P), and SR Ivocap High Impact (I). The CA of the surface of the unaltered, mechanically polished, and sandblasted surface specimens was evaluated after the application of five saliva substitutes: Biotene, VEGA, Spry, Moi-Stir, Dentilube, and ionized water. Ten droplet measurements were obtained for each group, with each droplet analyzed for advancing contact angle (ACA), receding contact angle (RCA), and the contact angle hysteresis (CAH) was calculated. The data of the experiment was analyzed using 2-way ANOVA, (α = 0.05) with Tukey's test., Results: CAH was demonstrated to have statistically significant differences among the denture bases (p < 0.05), with unaltered 3D printed exhibiting the largest CAH, followed by unaltered milled. The unaltered denture bases exhibited higher CAH than the polished, and there were no significant differences in CAH among the polished denture bases (p > 0.05). Sandblasting increased the ACA of the milled and conventional bases. The saliva substitutes exhibited differences in ACA, with Spry and VEGA having the highest ACA, and Biotene had the lowest CA of all the saliva substitutes evaluated., Conclusion: The manufacturing methods of denture bases influences the CAH, while the chemical composition of the denture base specimens does not appear to affect CAH. Sandblasting increases the ACA for the milled and conventional groups. Saliva substitutes do impact the ACA. Drawing from previous research, it is hypothesized that a 3D-printed denture base or sandblasting a milled denture base may offer greater resistance to dislodgement., (© 2024 The Author(s). Journal of Prosthodontics published by Wiley Periodicals LLC on behalf of American College of Prosthodontists.)

Purpose: This study evaluated the effect of thermocycling and three different surface finishing protocols on the flexural strength and surface hardness of a novel photopolymer intended for manufacturing monolithic polychromatic dental prostheses using PolyJet 3D printing., Materials and Methods: A total of 90 specimens were manufactured using a photopolymer for 3D printing monolithic polychromatic dental prostheses using PolyJet technology (TrueDent; Stratasys USA). The specimens were divided into three groups (n = 30) according to the surface finishing protocol used: The control group Pumice+Moldent (Pumice), Pumice+Optiglaze (Optiglaze), and Polycril+Moldent (Polycril). Half of the specimens of each group (n = 15) were subjected to 5000 thermocycles (Thermocycling Unit OMC350TSX; Odeme Dental Research, Santa Catarina, Brazil), The other half was stored in distilled water at room temperature for 7 days before testing. The flexural strength of the specimens was assessed in a universal testing machine (MTS Sintech ReNew; MTS Systems Corp, Aiden Prairie, MN), and the Vicker's surface hardness was evaluated with a microhardness tester (Micro indentation Hardness Tester LM247AT; Leco Instruments Ltd, Ontario, Canada). The resulting data was analyzed using two-way ANOVA tests, and Fisher's protected least significant differences (α = 0.05) in a professional statistical analysis computer program (SAS v9.4, SAS Institute, Cary, NC) RESULTS: The two-way ANOVA tests suggested a statistically significant effect of thermocycling and the surface finishing protocol on the flexural strength (p = 0.01) but without significant interaction between both independent variables (p = 0.18). The post hoc analysis revealed no significant differences in the flexural strength between groups without thermocycling (p > 0.05). Thermocycling decreased the flexural strength of all groups (p < 0.05), and the Optiglaze group exhibited significantly higher flexural strength than the Polycril and Pumice groups after thermocycling (p < 0.01). Regarding the surface hardness, the two-way ANOVA indicated a significant 2-way interaction between thermocycling and the surface of the finishing protocol (p = 0.01). The post hoc analysis showed that the Optiglaze group had significantly higher hardness than the other groups, both before and after thermocycling (p < 0.01) After thermocycling, a significant decrease in surface hardness was observed in the Polycril and Pumice groups (p < 0.01)., Conclusions: Surface finishing protocols and artificial aging can affect the surface hardness and flexural strength of the dental prostheses manufactured using the photopolymer studied. Careful polishing and surface finishing are required to ensure favorable clinical performance. Coating with a photopolymerizable glaze material seems to be a favorable surface treatment for monolithic polychromatic complete dentures fabricated using PolyJet 3D printing., (© 2024 The Author(s). Journal of Prosthodontics published by Wiley Periodicals LLC on behalf of American College of Prosthodontists.)

3D-printed shell complete dentures generated from a scan of the patient's existing prostheses can simplify and expedite the surgical planning and interim restoration design for complete arch rehabilitations. Three patients were rehabilitated with endosteal implants, and interim restorations were generated from the contours of the 3D-printed shell complete dentures used as diagnostic aids. This case series report presents the recommended protocol and its clinical progression, in addition to clinical and radiographic images of the treatment outcomes., (© 2024 The Author(s). Journal of Prosthodontics published by Wiley Periodicals LLC on behalf of American College of Prosthodontists.)

Purpose: The present study evaluated the effects of the root portion design, segment (middle vs. apical), and part (die vs. cast) on the trueness of three-dimensional (3D)-printed removable die-cast complex., Material and Methods: The trueness of apical and middle segments of the root portion of 45 3D-printed removable dies and casts with three different root portion designs (n = 15) was assessed using a metrology-grade computer program. The three removable dies and cast designs (root form [RF], conical [CON], and cylindric [CYL]) were created using professional computer-aided manufacturing computer programs (DentalCAD 3.1 Rijeka, and InLab CAD 22.0), and manufactured using stereolithographic 3D printer (Form3; FormLabs, Somerville, MA). Subsequently, the 3D-printed removable dies and casts were scanned by a single operator with an intraoral scanner (PrimeScan; Dentsply Sirona, Charlotte, NC), and their respective standard tessellation language files were aligned and compared to master reference files in a metrology-grade computer program (Geomagic Control X; 3D systems, Rock Hill, NC). The root mean square (RMS) values of the middle and apical segments for each removable die and cast were calculated and analyzed using a mixed model including a repeated measure 3-way analysis of variance (ANOVA) and post-hoc stepdown Bonferroni-corrected pairwise comparisons (α = 0.05)., Results: A statistically significant 3-way interaction between factors was detected, suggesting that the part (removable die or alveolar cast) and their design affected the RMS values of their apical and middle root portion segment. (p = 0.045). The post-hoc analysis identified significant differences between RMS values of the apical segments of the CON and CYL removable dies (p = 0.005). Significant differences were observed between the middle and apical segments of the CON (p < 0.001) and RF removable die designs (p = 0.004). No statistically significant differences were noticed between the RMS of the different alveolar cast designs (p > 0.05). Significant differences were detected between the apical and middle segments of the same alveolar cast design (p < 0.05)., Conclusions: For the manufacturing trinomial and 3D printing strategy used in the present study, the interaction of the part, design, and segment affected the trueness of removable dies and alveolar casts. The trueness was higher on the middle segment on removable dies and alveolar casts in all designs used, except for CYL removable dies, where the trueness difference between segments was small. Higher trueness values may be achieved with designs with simple apical segment geometries., (© 2024 The Author(s). Journal of Prosthodontics published by Wiley Periodicals LLC on behalf of American College of Prosthodontists.)

Effect of model resin and shaft taper angle on the trueness and fit of additively manufactured removable dies in narrow ridge casts Purpose. To evaluate how model resin and shaft taper affect the trueness and fit of additively manufactured removable dies in narrow ridge casts., Material and Methods: A typodont model with a prepared mandibular molar was scanned to design virtual dies with different shaft tapers (0-degree (straight), 5-degree, and 10-degree tapered). Fifteen dies and one hollowed cast per taper were additively manufactured from two resins (G-PRINT 3D Model, GP and DentaMODEL, DM). Dies and casts were digitized to evaluate their trueness (root mean square (RMS)). The fit of the dies was evaluated with crown portion's RMS when seated in the cast and with distance deviations. Kruskal-Wallis and Mann-Whitney U tests were used to analyze data (α =.05)., Results: GP dies had lower overall, root, and base RMS, while DM dies had lower crown RMS (P≤.016). Straight dies had the highest overall, root, and base RMS within GP (P≤.030). Ten-degree dies had the lowest overall and base RMS, lower crown RMS than straight, and lower root RMS than 5-degree dies within DM (P≤.047). When the dies were seated, GP had lower crown portion RMS within 5- and 10-degree dies, and 5-degree dies had the highest RMS within DM (P≤.003). GP had lower distance deviations within 5- and 10-degree dies. Five-degree dies had the highest deviations within DM (P≤.049)., Conclusions: GP dies mostly had higher trueness and better fit. Straight dies mostly had lower trueness within GP. Ten-degree taper mostly led to higher trueness within DM. The shaft taper affected DM dies' fit.

Computer-aided design and computer-aided manufacturing systems enable digital designing and 3-dimensional (3D) printing of definitive casts with removable dies. However, the fit of the removable dies should be without interferences for their accurate positioning in the cast. Given that the accuracy of additive manufacturing depends on design- and manufacturing-related factors, verifying the accuracy of the position of 3D-printed removable dies in their cast is essential to fabricate positionally accurate definitive prostheses, which would enable minimal or no laboratory and clinical adjustments. This dental technique article presents a straightforward approach to verify the seating of a 3D-printed removable die by using verification matrices made of a polyvinylsiloxane interocclusal registration material., (© 2024 The Authors. Journal of Prosthodontics published by Wiley Periodicals LLC on behalf of American College of Prosthodontists.)

Purpose: To evaluate the effect of heated and room-temperature hydrofluoric (HF) acid on surface roughness parameters (Ra and Rq) and microtensile bond strength (μTBS) on feldspathic ceramic and lithium-disilicate glass-ceramics., Materials and Methods: Disk-shaped samples made from both ceramics were divided into groups according to surface treatment: feldspathic ceramic polished surface (FP), feldspathic ceramic + 60 s of 9% HF acid etching at room temperature (FC), feldspathic ceramic + 60 s of 9% HF acid etching heated to 70°C (F70), lithium-disilicate polished surface only (LP), lithium disilicate + 20 s of 9% HF acid etching at room temperature (LC), and lithium disilicate + 20 s of 9% HF acid etching heated to 70°C (L70). To evaluate Ra and Rq, non-overlapping readings were taken on the surface of each sample with a contact stylus profilometer. To measure microtensile bond strength (μTBS), samples of groups FC, F70, LC and L70 received their corresponding surface treatment, were silanized and then bonded using a dual-cure composite cement to resin composite disks. After 24 h, samples were sectioned to obtain specimens for μTBS. Representative samples from each group were examined using scanning electron microscopy (SEM) to analyze the morphology of the etched surface. The data were analyzed for statistical significance using Welch's ANOVA with the Games-Howell multiple-comparison post-hoc test., Results: For both surface roughness parameters and HF acid etching at room temperature (FC and LC) showed a significant increase (p < 0.001) in surface roughness when compared to polished surfaces (FP and LP). Furthermore, the use of heated HF acid etching significantly increased (p < 0.001) the surface roughness of the ceramic when compared to their counterpart sample of HF acid etching at room temperature. Group L70 obtained the highest μTBS of all groups (29.11 ± 8.26 MPa) and was significantly higher (p < 0.001) than that of the other experimental groups. There were no statistical differences (p > 0.05) between groups FC (19.94 ± 4.14), F70 (18.24 ± 5.29), and LC (17.87 ± 6.96)., Conclusion: The use of 9% HF acid etching heated to 70°C resulted in significantly higher surface roughness and improved bond strength onto lithium-disilicate glass-ceramic compared to surface HF acid etching at room temperature.