The International journal of prosthodontics最新文献

Purpose: To investigate the available evidence on the accuracy of conventional and digital workflows for complete arch implant supported frameworks. Materials and methods: This scoping review was conducted according to the 5-stage framework of Arksey and O'Malley. A systematic literature search was performed adhering to the PRISMA guidelines to identify studies with a direct comparison of conventional and digital methods for the fabrication of complete arch implant supported frameworks. 58 in-vitro studies with the focus on edentulous arches with at least four implants published between 2000 and 2024 were included. The reported outcomes were examined to determine the value of a statistical analysis for adding up the individual errors to a cumulative error of the workflow. Results: Evidence on the accuracy assessment of digital and conventional workflows for complete arch implant supported frameworks is available. However, also studies with the same assessment methods and outcome units appear to be too heterogeneous to perform a statistical analysis of error accumulation. While there is no consensus in the impression and cast fabrication stage, digital techniques show a superior accuracy for the fabrication of complete arch implant supported frameworks compared to conventional casting. Conclusion: In-vitro studies assessing the accuracy of entire workflows and classifying their outcomes regarding the clinical relevance are lacking.

Purpose: The improvement of computer-aided design and computer-aided manufacturing (CAD/CAM) has changed the methods of fabricating laminate veneers. The objectives of this study were to evaluate the marginal and internal fit of ceramic veneers manufactured with different CAD/CAM techniques. Materials and methods: A metal die was made by copying a prepared plastic maxillary central right incisor and scanned for designing a laminate veneer. One hundred laminate veneers were made with four different CAD/CAM techniques (n=25), including milled lithium disilicate (MLD), heat-pressed lithium disilicate with 3-dimensional (3D) printed wax patterns (PLD), milled zirconia (MZ), and 3Dprinted zirconia (PZ). The virtual marginal and internal fit of fabricated veneers was evaluated with digital crown fitting software. The actual marginal and internal fit was measured with the silicone replica method under a digital microscope. The measured data were analyzed using the one-way analysis of variance and the Turkey test. Results: There were significant differences in marginal and internal fit (P < 0.001) among manufacturing techniques. Both the virtual and actual marginal and internal gaps were higher in the PLD and PZ groups compared to the MLD and MZ groups. Conclusion: All four CAD/CAM techniques of manufacturing veneers, that is, milled lithium disilicate, heat-pressed lithium disilicate with 3D-printed wax patterns, milled zirconia, and 3D-printed zirconia, have clinically acceptable marginal and internal fit. Milled zirconia and lithium disilicate veneers demonstrated superior marginal and internal fit compared to 3D-printed zirconia and heat-pressed lithium disilicate veneers with 3D-printed wax patterns.

Purpose: To analyze the microgap changes between hybrid-abutment crowns made of two materials and three internal taper connec9on implants with different connection designs before and after thermodynamic loading.

Materials and methods: A total of 30 implants-10 each of Straumann Bone Level Implant-RC (STR); GC AADVA Implant (AAD); and Astra-Tech OsseoSpeed EV (AST)-were included in this laboratory study. Each implant had an internal taper connection, but their designs were slightly different. Five hybrid-abutment crowns were fabricated using a lithium disilicate ceramic (LD), and five were fabricated using polymethylmethacrylate (PMMA) with CAD/CAM technologies for each implant system, providing six sample groups STR-LD, AAD-LD, AST-LD, STR-PMMA, AAD-PMMA, and ASTPMMA. The microgap volume was measured using micro-CT images obtained before and after thermodynamic loading equivalent to 4 months of clinical use. Student t test, one-way ANOVA, and Tukey test were used for comparisons.

Results: The greatest microgap volume increase was recorded (3.405% ± 1.567%) in the AST-LD group, and the lowest increase (0.45% ± 0.373%) was in the STR-PMMA group. A statistically significant difference in microgap increase was not detected among PMMA and LD groups: for STR-LD/STR-PMMA (t test: P = .273); for AAD-LD/AAD-PMMA (t test: P = .374); and for AST-LD/AST-PMMA (t test: P = .268). However, the difference in the microgap increase between the different implant systems was statistically significant.

Conclusions: The microgap between hybrid-abutment crowns and implants increased after short-term thermodynamic cycling. Hybrid-abutment crowns with different elastic modulus showed similar microgap increase. The geometric shape of the connection influenced the microgap increase.

Purpose: To analyze the effect of disinfectants on the roughness and mechanical properties of CAD/ CAM polymethylmethacrylate (PMMA) dentures.

Materials and methods: Two groups of denture base resins were tested-heat-polymerized and milled blocks. For each resin, 120 specimens were produced for flexural strength (FS) and flexural modulus (FM) analyses (total: 240 specimens), and 40 were produced for microhardness and surface roughness evaluations (total: 80 specimens). They were categorized into the following groups based on immersion: control (deionized water); H1 (1% sodium hypochlorite); H05 (0.5% sodium hypochlorite); and C2 (2% chlorhexidine) groups. The immersion periods were 0 (T0), 130 (T1), and 260 (T2) cycles. Statistical analyses were performed for flexural properties using threeway ANOVA. Microhardness (KHN) and surface roughness (Ra) were analyzed using repeated-measures ANOVA. A significance level of 5% was set.

Results: CAD/CAM PMMA showed higher FS (P = .001) and FM (P < .001) than conventional PMMA. The KHN value was superior to the conventional PMMA (P < .001). The chemical solution affected the surface roughness of both resins (P = .007). The CAD/ CAM PMMA block showed increased Ra values when H1 was used. Cycling separately increased the FS of conventional PMMA (T1 vs baseline; P < .05). However, the FM of CAD/CAM PMMA was higher (T1 and T2 vs baseline; P < .05). The time factor increased the microhardness of both resins (T2 vs baseline; P < .05).

Conclusions: The CAD/CAM resin showed higher values compared to conventional PMMA in all tests, regardless of the chemical solution used; however, the values obtained for both resins were clinically acceptable.

Purpose: To evaluate the effect of different finishing protocols on the wear behavior of lithium disilicate glass-ceramics (LD).

Materials and methods: Specimens were produced from LD prefabricated CAD/CAM blocks and divided into three groups according to the surface treatment (n = 8): control, polishing, and glaze. Ceramic specimens were subjected to wear testing using a dual-axis chewing simulator. A 49-N load was applied in the axial direction combined with a lateral movement (1-mm path) using an LD spherical piston for a total of 106 cycles. Qualitative analysis of the wear surface was performed using an optical microscope. Quantitative analysis of surface roughness and volume loss was performed using a confocal microscope and a 3D-image editing software, respectively. Surface roughness and volume loss data were analyzed using Friedman's nonparametric statistical test for repeated measures and the Student-Newman-Keuls test (α = .050).

Results: There were statistical differences for surface roughness and volume loss of LD specimens in the different experimental conditions (P < .001). The control and polishing groups showed similar surface roughness and volume loss values for all testing times. The glaze group had greater wear volume after 103, 104, and 105 cycles. After 106 cycles, surface roughness and volume loss were similar in all groups. For the piston, surface roughness was similar over time and among groups.

Conclusions: A distinct wear behavior was found for glazed glass-ceramic specimens compared to control and polished specimens. At the end of the simulation, the surface roughness and volume loss was similar for the groups.

Purpose: To examine if there are differences in smile esthetic evaluation scores by orthodontists and prosthodontists and if there are changes in those scores when two evaluations are performed, when the time of observation is increased, and when the lips are present or absent from the images.

Materials and methods: In total, 12 individuals participated in this pilot study. Two digital images were taken from each individual. The first digital image was a smile view, and the second image was an intraoral view. Two presentation files were prepared, with two images for each individual. The smile and dental attractiveness ratings were obtained from 10 specialists.

Results: Repeated measures ANOVA was applied including all four within-subject factors, the evaluator (E), the repetition (R), the time of observation (T), and the presence or not of lips (L). Factors E, T, and L each had a statistically significant main effect. E and R had a statistically significant combined effect. In particular, the esthetic score for the view with smile was overall higher than for the intraoral view. The same results were obtained when the analysis was repeated with the 10 evaluators grouped to prosthodontists and orthodontists, and the prosthodontists tended to score higher than the orthodontists.

Conclusions: The evaluator and the presence of lips have a statistically significant effect. The present pilot study has found that three (E, L, R) out of four factors (T) are important for the evaluation of dental esthetics.

Purpose: To determine the values of 15 craniofacial linear distances in the Serbian ethnic group using and comparing two methods of face-anthropometric and digital 2D-face-photogrammetric measurement and to determine the correlations between distances that can be predictive or can serve as proxy for occlusal vertical dimension (OVD).

Materials and methods: A total of 90 adults were selected. Facial distance as a tool to measure the OVD was measured as Sn-Gn (the distance between the septum of the nose [Sn] and the tip of the chin [Gn]). Face-anthropometric measurements were made with a Boley gauge (Buffalo Dental). Digital 2D-photogrammetric facial measurements were performed using the computer program Dr Ceph (FYI Technologies).

Results: The mean value for the distance Sn-Gn was 63.55 using face-anthropometric measurement (Sn-Gn[f]) and 63.56 using 2D-face-photogrammetic measurement (Sn-Gn[ph]) Multivariate regression analysis revealed that Sn-Gn(f) depended on ExL-ExR(f) P = .001; ZyL-ZyR(f) P = .077; N-Sn(f) P = .096; Sn-Sto(f) P = .043; and sex. Analysis also identified that Sn-Gn(ph) depended on ExL-ExR(ph) P < .001; EnL-EnR(ph) P = .029; N-Sn(ph) P = .013; Sn-Sto(ph) P = .001; and sex.

Conclusions: A comparison of facial anthropometry and digital 2D-facial photogrammetry revealed no statistical significance differences in the values obtained and showed that facial photogrammetry could be as reliable a method as facial anthropometry.

This article reports a case of maxillary rehabilitation with implant-supported fixed dental prostheses on six zirconia implants. A woman with impacted maxillary canines attended our dental clinic seeking a metal-free maxillary restoration. After the extraction of both impacted maxillary canines and the placement of autogenous bone graft, six two-piece zirconia implants with straight abutments were placed in the anterior maxilla. Two zirconia fixed dental prostheses with porcelain veneering, separated at the midline, were placed on these zirconia implants. The 10-year follow-up monitored the adequate evolution of both implants and restorations with no signs of peri-implant disease.

Purpose: To compare the peri-implant bone loss of mandibular complete-arch implant-supported fixed prostheses (FPSs) supported by three and four implants and to correlate with the size of the horizontal and vertical distal cantilever at prosthesis placement (T1) and after 1 year (T2).

Materials and methods: A total of 72 external hexagon (EH) type implants were placed in 20 participants. Of these, 24 supported an FPS with three implants (G3I) and 48 with four implants (G4I). The mandibular implants were named 1, 2, 3, and 4 according to their location in the arch, in a clockwise direction. Digital periapical radiographs were taken at times T1 and T2 for analysis and measurement of peri-implant bone loss. The horizontal and vertical distal cantilevers were measured with a digital caliper and correlated with peri-implant bone loss.

Results: The survival rate of implants in G3I was 91.66%, and in G4I it was 97.91%. The mean bone loss in G3I was 0.88 ± 0.89 mm, and in G4I it was 0.58 ± 0.78 mm (P = .225). There was no correlation between distal horizontal cantilevers and bone loss in the studied groups, with G3I being -0.25 (P = .197) and G4I -0.22 (P = .129). Larger vertical cantilevers of implants 1 (P = .018), 3 (P =.015), and 4 (P = .045) correlated with greater bone loss in G4I.

Conclusions: The number of implants in an FPS did not influence peri-implant bone loss after 1 year of follow-up. Larger vertical cantilevers influenced greater bone loss in complete-arch implant-supported fixed prostheses supported by four implants.

Purpose: To validate the effectiveness of a simplified ultrasonic cleaning protocol to clean customized abutments, and to investigate the percentage of pollutants on customized abutments provided by the implant company and the additional effect of dental laboratory manipulations.

Materials and methods: A total of 24 customized abutments were divided in two groups, 12 returning from the implant company and 12 others returning from the dental laboratory. In each group, there were 6 zirconia (Zr02) abutments and 6 .tanium (Ti) abutments. For each condition, half of the samples were cleaned with the experimental protocol, and the others were left as delivered by the company. The two-step cleaning protocol consisted of mechanical treatment with a sterile compress soaked in a detergent over the transgingival part of the abutment, followed by three successive ultrasound baths for two minutes/bath. The presence of pollutants was quantified using scanning electron microscopy.

Results: The suggested cleaning method allowed to significantly decrease the quantity of pollutants (P = .0006). The abutments returning from the dental laboratory were significantly more polluted than those coming directly from the implant company (P = .0043). The cleaning effect was highly significant in both groups (P < .0001). The quantity of pollutants before cleaning were similar in the titanium and in the zirconia groups and the cleaning effect was highly significant in both groups (P = .0009).

Conclusions: The cleaning protocol tested was successful on the customized abutments from each group.