The International journal of prosthodontics最新文献

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.

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.

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 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.

Purpose: To evaluate the stress distribution along a premolar's root dentin, its post, and its post-luting agent when materials with different elastic moduli are used to fabricate one-piece post-and-cores in two different designs.

Materials and methods: Two 3D virtual models (for cylindrical and conical post designs) of a mandibular premolar restored with one-piece post-and-core restorations were obtained using a software. A total of eight post-and-core materials were tested: polyetheretherketone (PEEK), polyetherketoneketone (PEKK), glass fiber-reinforced polyetheretherketone (GFR-PEEK), carbon fiber-reinforced polyetheretherketone (CFR-PEEK), gold-palladium alloy (Au-Pd), titanium (Ti), zirconia (Zi), and chromium-nickel (Cr-Ni). Maximum principals stress (MPS) in the post, post-luting agent, and root dentin were determined. A load of 150 N was applied to the buccal cusp in the linguo-labial direction at an angle of 45 degrees oblique to the longitudinal axis of the crown.

Results: The highest MPS value in post structure was observed with Cr-Ni material for both post designs. Similarly, the highest MPS value in the post-luting agent was observed for Cr-Ni, the material with the highest elastic modulus. However, in the root dentin, the highest value was observed in PEEK, the material with the lowest elastic modulus.

Conclusions: Post material and design influenced the stress concentration in the post, post-luting agent, and root dentin. The stress at the root dentin was slightly higher for polymeric materials. Cylindrical post design revealed lower stresses than conical post design at root dentin for all post-and-core materials tested.

Purpose: To evaluate how the crown-to-implant (C/I) ratio affects the loss of crestal bone at single-crown implants and bridges in patients with periodontal disease.

Materials and methods: A total of 39 patients treated for periodontitis were rehabilitated with 108 implant-supported single crowns and bridges. Each patient was examined over a 5- to 20-year period on a 3- to 6-month recall schedule. At each session, we recorded periodontal clinical parameters. In addition, intraoral radiographs were taken after superstructure insertion (baseline) and then at 1, 3, 5, 10, 15, and 20 years. The study population was divided by anatomical C/I ratio (Group 1: C/I ≤ 1, Group 2: C/I > 1).

Results: Implants had a 96.2% 5-year survival rate and 92.6% 20-year survival rate. The overall prevalence was 10.1% for mucositis and 1.1% for peri-implantitis. The survival rate (P = .68), incidence of mucositis (P = .325), and incidence of peri-implantitis (P = .077) did not significantly differ in the group comparison. The mean annual peri-implant bone loss was 0.09 ± 0.41 mm and was not significantly different between the groups. Mean bone loss was not significantly different until the 10th year of observation, during which Group 2 presented significantly less bone loss. The correlation of annual bone loss and clinical C/I ratio showed a small but significant negative effect throughout the entire study period (R = -0.217; P < .01).

Conclusions: Increased crestal bone loss was not observed with implants with higher C/I ratios, both anatomical and clinical, and they even showed signs of less crestal bone loss.

In our previous test model, the abutment teeth and the model base were printed with resin and bonded with a polyether material. Some abutment teeth were fractured during the mechanical load test. Therefore, the aim was to develop and evaluate a new model under mechanical loading until fracture with zirconia FPD frameworks. At a fracture load of up to 1,636 N, neither the artificial abutment teeth nor the base model fractured. Furthermore, the artificial abutment teeth did not detach from the base model. Therefore, the model should be suitable for mechanical testing of most ceramic-based framework materials for three-unit FPDs.