1,721,040 research outputs found
Retrospective clinical study of 1472-unit monolithic zirconia restorations with feather-edge margins realized with digital workflow
No full textObjectives: To evaluate the clinical performance of monolithic zirconia restorations with feather-edge margins fabricated by digital impressions. Materials and methods: All participants that present monolithic zirconia restorations with feather-edge margins realized with digital workflow were evaluated during scheduled periodontal maintenance between February and September 2022 according to predetermined inclusion criteria. Clinical performance was assessed using the modified USPHS and periodontal parameters. Overall survival was calculated for monolithic zirconia restorations. Technical and biologic complications were reported. Descriptive statistical analysis and life-table analyses were performed for all data. Results: A total of 1472 monolithic zirconia FDPs (1279 on abutments and 193 on pontics) placed in 1189 patients (982 males and 490 females) from February 2017 to September 2020 were analyzed. The mean follow-up was 44 months (range 36-61 months), and the overall survival rate was 98.5%. There were 931 single crowns, 96 were 3-unit FDPs, 33 were 4-unit FDPs, 11 were 5-unit FDPs, and 6-unit FDPs. Three single crowns had irreparable cracks, and 6 single crowns and one 4-unit FDP were fractured. One 3-unit FDP failed due to tooth fracture and 5 single crowns failed due to endodontic failure. The loss of retention was noted in 25 monolithic zirconia FDPs and hypersensitivity in 44 single crowns. Biologic complications were uncommon. Conclusions: Based on the results and its limitations, the monolithic zirconia FPDs and digital impressions represent a favorable prosthetic treatment similar to that reported with other margin designs CLINICAL RELEVANCE: Monolithic zirconia restorations on vertical-margin abutments fabricated using a digital workflow demonstrate excellent clinical performance. The digital clinical workflow without the use of a cast means a reduction in costs, steps, and operating time
A Standardized Approach for the Early Restorative Phase After Esthetic Crown-Lengthening Surgery
No full textThe aim of the present case series article was to provide a standardized approach for the early restorative phase after a crown-lengthening surgical procedure. Different advantages can be ascribed to this approach: the clinician can prepare a definitive prosthetic finishing line in the supragingival location; the early postsurgical temporization allows the conditioning of soft tissues, especially the interdental papillae, during their maximum growing phase; and the clinician can choose the time for the definitive prosthetic rehabilitation in a patient-specific manner according to the individual potential and duration of the soft tissue rebound. In this study, this standardized approach was applied to the treatment of two esthetic cases requiring crown-lengthening procedures
Implant Digital Impression in the Esthetic Area
No full textThe aim of this report is to describe two standardized protocols for digital impression when implant support rehabilitation is used in the esthetic area. The two techniques were used to transfer all provisional crown parameters to definitive restorations in different clinical scenarios. In the direct technique, an impression (STL1) is made of the provisional restorations attached to the implants, with surrounding gingival tissue. The second scan (STL2) captures the sulcular aspect of the peri-implant soft tissue immediately after removal of the provisional restoration. The last impression (STL3) of the complete arch is made with a standardized scanbody attached to the implant to capture the 3D location of the implant. The direct technique is indicated when the peri-implant soft tissues are stable upon removal of the provisional restoration. The indirect technique is used when the gingival tissue collapses rapidly after the removal of the provisional crown. The impressions of the provisional restoration and the position of the implant are similar to those obtained with the direct technique, and the shape of the peri-implant tissue is extrapolated from the negative shape obtained from making the digital impression when the provisional restoration is taken out of the mouth. Finally, in both techniques the 3 scans are superimposed to obtain a file, which contains the details of the peri-implant soft tissue. The direct and indirect digital techniques allowed realization of a predictable definitive restoration in the esthetic zone in different clinical scenarios, reducing the duration of clinical procedures
Bond Strength to Cubic Zirconia and Lithium-disilicate. A Preliminary Study
No full textObjectives: Bonding to polycrystalline ceramics is a concern in fixed prosthodontics. Aim of this study was to determine the micro-SBS of two MDP-based cements to cubic-zirconia (ZIR) and lithium-disilicate (L-DIS).
The null hypothesis was that mean micro-SBS did not vary among tested groups.
Methods: Twenty plates 12x12x2mm of Katana-UTML, (Kuraray-Noritake), and 20 of IPS e.max CAD LT, (Ivoclar-Vivadent) were used as substrates. They were assigned to 4 groups (n=40) according to the combination with two resin-cements: PanaviaV5 (PV5) + Clearfil-Ceramic-Primer-Plus, (groups PV5/ZIR and PV5/L-DIS); PanaviaSA (PSA) self-adhesive cement, (groups PSA/ZIR and PSA/L-DIS).
The ceramics were pre-treated following the cements manufacturer instructions: ZIR-tablets were sandblusted (Al2O3 powder, 50mm); L-DIS-tablets were conditioned (35% H3PO4, K-Etchant Syringe).
Four cylinders (1.7mm diameter, 2mm height) of resin-cement were applied on each plate with vertical load (1Kg) and light-cured (20sec).
All samples were stored in water (37°C, 24h) and tested for micro-SBS (Instron-machine). Failed surfaces were analyzed under optical-microscope and failure pattern was determined (adhesive, cohesive or mixed). Percentage of actual-failed/total adhesive surface was calculated with dedicated software (Zeiss ZEN). Mean micro-SBS values were measured (MPa) and statistically analyzed (Kruskall-Wallis-test, Dunn’s test, a=0.05).
Results: The null hypothesis that micro-SBS did not vary among the groups was rejected, (p<0.05). Mean values varied from 7.7±1.9MPa (PSA/L-DIS) to 19.6±1.7MPa (PV5/ZIR). All groups were statistically different, except PSA/ZIR vs PV5/L-DIS, (p>0.05). Both cements presented significantly higher bond strength to ZIR than L-DIS substrate. For each substrate, PV5 showed higher bond strength than PSA. Adhesive failures were mostly observed in all groups. Mean percentage of actual-failed adhesive surface varied from 69.5% (PSA/ZIR) to 85.1% (PV5/L-DIS).
Conclusions: ZIR treatment with MDP-based primer helped obtaining improved adhesion. L-DIS treatment with H3PO4 should be further investigated and compared with the conventional HF treatment. Micro-SBS measurements after longer aging conditions are needed to evaluate the bonding stability
Restoring Nonvital Premolars with Composite Resin Onlays: Effect of Different Fiber-reinforced Composite Layers on Marginal Adaptation and Fracture Load
No full textPURPOSE: To evaluate the marginal adaptation and fracture load of composite resin onlays reinforced with different substructures.MATERIALS AND METHODS: Thirty-two extracted, caries-free premolars were selected for this study and endodontically treated. Group 1 was used as the control group, and the teeth were restored only with as-manufactured composite resin overlays. Group 2 teeth were restored with composite resin overlays with 3 fiber-reinforced composite (FRC) layers placed horizontally on the bottom of the restoration. Group 3 teeth were restored with composite resin overlays with 6 fiber-reinforced composite (FRC) layers placed as in group 2. Group 4 teeth were restored with composite resin overlays and FRC placed with an anatomical design. All specimens underwent SEM evaluation of their marginal adaptation before and after thermocycling and cyclic mechanical loading. All specimens were then subjected to a fracture test, recording the value for the initial (IF) and final (FF) failure. Differences in the means were compared using matched-pairs t-tests and one-way ANOVA. The level of significance was set at α = 0.05.RESULTS: No statistically significant difference between the four groups in terms of marginal adaptation was observed at the tooth/luting composite and luting composite/overlay interfaces before and after loading. The fracture loads of IF and FF, from most to least resistant were: group 4 (1431.8 ± 294.3 N/1710.1 ± 326.6 N), group 3 (1428.1 ± 251.4 N/1467.9 ± 242.4 N), group 2 (852.6 ± 413.5 N/1058.1 ± 251.5 N) and group 1 (899.8 ± 352.7 N/923.5 ± 318.8 N). Significant differences (p = 0.026) were observed comparing group 1 to groups 2 and 3, and group 1 to 4. Three irreparable fractures were found in group 3, four in group 2, and five in groups 1 and 4.CONCLUSIONS: The presence or absence of reinforcement and the different configuration of the reinforcement fibers affect fracture strength but only partially the failure modality. The presence or absence of reinforcement does not alter marginal adaptation
The prototype concept in a full digital implant workflow
No full textBackground: The aim of this case report is to describe the innovative concept of a prototype use in a digital implant workflow. A prototype is required for simultaneous evaluation of the accuracy of a dental impression and esthetic and functional parameters before final framework realization. Case Description: Three digital impressions were obtained to create a master file, which contained information on the 3-dimensional (3D) position of the implant, the gingival architecture, and the esthetic and functional features of the provisional restoration. A stereolithographic master model (SMM) featuring implant analogs was 3D printed. Two prototypes were realized with the use of 2 different modalities. The first resin prototype (A), which lacked implant connections, was produced with the use of a certified digital workflow process. The titanium connections were luted onto the SMM. The second resin prototype (B), considered experimental, was a single piece with milled implant connections. Both prototypes were tested in the patient by means of visual inspection, finger pressure testing, screw resistance testing, and periapical radiography. In the case of accurate fit of prototype A or B on the SMM and misfit in the patient, the impression should be invalidated. For prototype B, in the case of proper fit in the patient and misfit on the SMM (because of the occurrence of an error during 3D printing, incorrect analog position, or both), the impression should be validated, but the model should be adapted. Conclusions and Practical Implications: The use of a prototype allows the clinician to simultaneously test implant position and esthetic and functional parameters. However, a single-structure prototype could be preferable for the identification of impression inaccuracy
Disinfection protocols during COVID-19 pandemic and their effects on prosthetic surfaces: a systematic review
No full textTo describe the possible adverse effects of sodium hypochlorite (NaOCl) solutions, high-concentration alcohol solutions, and povidone-iodine products, which are indicated for disinfection of inanimate surfaces against human coronavirus of the severe acute respiratory syndrome (SARS-CoV), on prosthesis materials, including zirconia, lithium disilicate, and acrylic resin
Fracture strength of endodontically treated teeth restored with composite overlays with and without glass-fiber reinforcement
No full textPurpose: To evaluate the fracture strength and the failure mode of endodontically treated teeth restored with composite resin overlays with and without glass-fiber reinforcement. Materials and Methods: A total of 32 extracted molars were divided into four equal groups. In the NFR-NFRC (no foundation restoration, no fiber-reinforced composite) and NFR-FRC (no foundation restoration, fiber-reinforced composite) groups, only a 5-mm-thick composite resin layer sealed the pulp chamber floors, whereas in the FR-NFRC (foundation restoration, no fiber-reinforced composite) and FR-FRC (foundation restoration, fiber-reinforced composite) groups, a 3.0-mm foundation restoration was used. NFR-NFRC and FR-NFRC groups were restored with composite resin overlays, whereas NFR-FRC and FR-FRC groups were restored with fiber-reinforced composite resin overlays. All specimens were subjected to mechanical loading in a computer-controlled masticator and then the fracture resistance was evaluated. Differences in means were compared using two-way ANOVA and Tukey's test. The level of significance was set at α = 0.05. Results: All specimens successfully completed the fatigue test. The least fracture-resistant group was NFR-FRC, exceeded by FR-NFRC, NFR-NFRC, and FR-FRC, in that order, with FR-FRC being the most fracture-resistant group. Statistically significant differences were detected between the pairs NFR-NFRC/FR-FRC (p = 0.001), NFR-FRC/FR-FRC (p = 0.001), and FR-NFRC/FR-FRC (p = 0.001). Eight vertical root fractures occurred in group FR-NFRC, six in group NFR-NFRC, four in group NFR-FRC, and none occurred in group FR-FRC. Conclusions: Within the limitations of this in vitro study, the incorporation of glass fibers and the presence of a foundation restoration were found to increase the fracture resistance and can favorably influence the fracture mode
Clinical outcome of monolithic zirconia on bonded or mechanically retained prefabricated titanium-base: A 4-year retrospective study
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