Objectives
This study aimed to evaluate the accuracy of intraoral scanners in full-arch scans.
Materials and methods
A representative model with 14 prepared abutments was digitized using an ...industrial scanner (reference scanner) as well as four intraoral scanners (iTero, CEREC AC Bluecam, Lava C.O.S., and Zfx IntraScan). Datasets obtained from different scans were loaded into 3D evaluation software, superimposed, and compared for accuracy. One-way analysis of variance (ANOVA) was implemented to compute differences within groups (precision) as well as comparisons with the reference scan (trueness). A level of statistical significance of
p
< 0.05 was set.
Results
Mean trueness values ranged from 38 to 332.9 μm. Data analysis yielded statistically significant differences between CEREC AC Bluecam and other scanners as well as between Zfx IntraScan and Lava C.O.S. Mean precision values ranged from 37.9 to 99.1 μm. Statistically significant differences were found between CEREC AC Bluecam and Lava C.O.S., CEREC AC Bluecam and iTero, Zfx Intra Scan and Lava C.O.S., and Zfx Intra Scan and iTero (
p
< 0.05).
Conclusions
Except for one intraoral scanner system, all tested systems showed a comparable level of accuracy for full-arch scans of prepared teeth. Further studies are needed to validate the accuracy of these scanners under clinical conditions.
Clinical relevance
Despite excellent accuracy in single-unit scans having been demonstrated, little is known about the accuracy of intraoral scanners in simultaneous scans of multiple abutments. Although most of the tested scanners showed comparable values, the results suggest that the inaccuracies of the obtained datasets may contribute to inaccuracies in the final restorations.
Statement of problem Preparation designs and ceramic thicknesses are key factors for the long-term success of minimally invasive premolar partial coverage restorations. However, only limited ...information is presently available on this topic. Purpose The purpose of this in vitro study was to evaluate the fracture resistance and failure modes of ceramic premolar partial coverage restorations with different preparation designs and ceramic thicknesses. Material and methods Caries-free human premolars (n=144) were divided into 9 groups. Palatal onlay preparation comprised reduction of the palatal cusp by 2 mm (Palatal Onlay Standard), 1 mm (Palatal-Onlay-Thin), or 0.5 mm (Palatal Onlay Ultrathin). Complete-coverage onlay preparation additionally included the buccal cusp (Occlusal Onlay Standard; Occlusal Onlay Thin; Occlusal Onlay Ultrathin). Labial surface preparations with chamfer reductions of 0.8 mm (Complete-Veneer-Standard), 0.6 mm (Complete-Veneer-Thin), and 0.4 mm (Complete Veneer Ultrathin) were implemented for complete veneer restorations. Restorations were fabricated from a pressable lithium disilicate ceramic (IPS-e.max-Press) and cemented adhesively (Syntac-Classic/Variolink-II). All specimens were subjected to cyclic mechanical loading (F=49 N, 1.2 million cycles) and simultaneous thermocycling (5°C to 55°C) in a mouth-motion simulator. After fatigue, restorations were exposed to single-load-to-failure. Two-way ANOVA was used to identify statistical differences. Pair-wise differences were calculated and P-values were adjusted by the Tukey-Kramer method (α=.05). Results All specimens survived fatigue. Mean (SD) load to failure values (N) were as follows: 837 (320/Palatal-Onlay-Standard), 1055 (369/Palatal-Onlay-Thin), 1192 (342/Palatal-Onlay-Ultrathin), 963 (405/Occlusal-Onlay-Standard), 1108 (340/Occlusal-Onlay-Thin), 997 (331/Occlusal-Onlay-Ultrathin), 1361 (333/Complete-Veneer-Standard), 1087 (251/Complete-Veneer-Thin), 883 (311/Complete-Veneer-Ultrathin). Palatal-onlay restorations revealed a significantly higher fracture resistance with ultrathin thicknesses than with standard thicknesses ( P =.015). Onlay restorations were not affected by thickness variations. Fracture loads of standard complete veneers were significantly higher than thin ( P =.03) and ultrathin ( P <.001) restorations. Conclusions In this in vitro study, the reduction of preparation depth to 1.00 and 0.5 mm did not impair fracture resistance of pressable lithium-disilicate ceramic onlay restorations but resulted in lower failure loads in complete veneer restorations on premolars.
Abstract Objectives The purpose of this study was to evaluate the shear bond strength between various commercial zirconia core and veneering ceramics, and to investigate the effect of thermocycling. ...Methods The Schmitz–Schulmeyer test method was used to evaluate the core–veneer shear bond strength (SBS) of three zirconia core ceramics (Cercon Base, Vita In-Ceram YZ Cubes, DC-Zirkon) and their manufacturer recommended veneering ceramics (Cercon Ceram S, Vita VM9, IPS e.max Ceram). A metal ceramic system (Degudent U94, Vita VM13) was used as a control group for the three all-ceramic test groups ( n = 30 specimens/group). Half of each group ( n = 15) was thermocycled (5–55 °C, 20,000 cycles). Subsequently, all specimens were subjected to shear force in a universal testing machine. Fractured specimens were evaluated microscopically to determine the failure mode. Results The initial mean SBS values in MPa ± S.D. were 12.5 ± 3.2 for Vita In-Ceram YZ Cubes/Vita VM9, 11.5 ± 3.4 for DC-Zirkon/IPS e.max Ceram, and 9.4 ± 3.2 for Cercon Base/Cercon Ceram S. After thermocycling mean SBS values of 11.5 ± 1.7 MPa for DC-Zirkon/IPS e.max Ceram, 9.7 ± 4.2 MPa for Vita In-Ceram YZ Cubes/Vita VM9, and 9.6 ± 4.2 MPa for Cercon Base/Cercon Ceram S were observed. Neither the differences between the SBS values of the all-ceramic test groups nor the influence of thermocycling on all groups were statistically significant. Irrespective of thermocycling the metal ceramic control group (27.6 ± 12.1 MPa, 26.4 ± 13.4 MPa) exhibited significantly higher mean SBS than all three all-ceramic groups tested. The all-ceramic groups showed combined failure modes as cohesive in the veneering ceramic and adhesive at the interface, whereas the metal ceramic group showed predominately cohesive fractures. Significance The results indicated that the SBS between zirconia core and veneering ceramics was not affected by thermocycling. None of the zirconia core and veneering ceramics could attain the high bond strength values of the metal ceramic combination.
Objectives: The purpose of this prospective long‐term study was to evaluate the incidence of the most common technical problems, namely screw loosening, screw fracture, fracturing of veneering ...porcelain and framework fracture in implant‐supported fixed partial dentures (FPDs), and assess the survival and success rate (event‐free survival) after 5 years of function.
Materials and methods: In 76 partially edentulous patients, a total of 205 3i‐implants (machined surface) were placed and restored with 112 implant‐supported FPDs (46 single crowns, 81 splinted crowns, seven FPD bridges and 23 FPDs with cantilevers). The survival rate of FPDs supported by implants was 94.5% (CI‐95: 90.1–98.8) after an average observation period of 5 years. The success rate (event‐free survival) of the FPDs was 80% (CI‐95: 87.3–72.7). After an observation period of 5 years the cumulative incidence of screw loosening was 6.7% (CI‐95: 1.8–11.5), the cumulative incidence for screw fracture was 3.9% (CI‐95: 0.1–7.7). Fracture of the veneering porcelain occurred in 5.7% (CI‐95: 1.2–10.2) of all FPDs. Fracturing of the suprastructure framework was rare (1%; CI‐95: 0–2.9). The overall complication incidence after 5 years was highest in the group of FPDs with cantilever, which showed the lowest success rate 68.6% (CI‐95: 50–87.3), followed by single crowns (77.6%; CI‐95: 53.3–100) and splinted crowns (86.1%; CI‐95: 59.5–100). No complication occurred in FPD bridges.
Conclusion: Fixed partial dentures supported by 3i‐implants showed low technical complications rates, the most common being loosening of the abutment screw. Managing these complications can cause extra amount of chair‐side time and patient dissatisfaction.
Abstract Objectives The aim of the study was to evaluate the marginal and internal fit of heat-pressed and CAD/CAM fabricated all-ceramic onlays before and after luting as well as after ...thermo-mechanical fatigue. Materials and methods Seventy-two caries-free, extracted human mandibular molars were randomly divided into three groups ( n = 24/group). All teeth received an onlay preparation with a mesio-occlusal–distal inlay cavity and an occlusal reduction of all cusps. Teeth were restored with heat-pressed IPS-e.max-Press* (IP, *Ivoclar-Vivadent) and Vita-PM9 (VP, Vita-Zahnfabrik) as well as CAD/CAM fabricated IPS-e.max-CAD* (IC, Cerec 3D/InLab/Sirona) all-ceramic materials. After cementation with a dual-polymerising resin cement (VariolinkII*), all restorations were subjected to mouth-motion fatigue (98 N, 1.2 million cycles; 5 °C/55 °C). Marginal fit discrepancies were examined on epoxy replicas before and after luting as well as after fatigue at 200× magnification. Internal fit was evaluated by multiple sectioning technique. For the statistical analysis, a linear model was fitted with accounting for repeated measurements. Results Adhesive cementation of onlays resulted in significantly increased marginal gap values in all groups, whereas thermo-mechanical fatigue had no effect. Marginal gap values of all test groups were equal after fatigue exposure. Internal discrepancies of CAD/CAM fabricated restorations were significantly higher than both press manufactured onlays. Conclusions Mean marginal gap values of the investigated onlays before and after luting as well as after fatigue were within the clinically acceptable range. Marginal fit was not affected by the investigated heat-press versus CAD/CAM fabrication technique. Press fabrication resulted in a superior internal fit of onlays as compared to the CAD/CAM technique. Clinical relevance Clinical requirements of 100 μm for marginal fit were fulfilled by the heat-press as well as by the CAD/CAM fabricated all-ceramic onlays. Superior internal fit was observed with the heat-press manufacturing method. The impact of present findings on the clinical long-term behaviour of differently fabricated all-ceramic onlays warrants further investigation.
The aim of this article was to evaluate the effectiveness of various implant neck configurations in the preservation of marginal bone level as well as to identify the available scientific evidence.
...Online and hand searches of the literature published from 1976 through 2009 were conducted to identify studies dealing with modifications in the implant neck area and marginal bone loss for at least a 5-year observation period. The search terms that were used, alone or in combination, were "implant neck," "marginal bone loss," "neck design," "bone resorption," "bone remodeling," and "implant collar." Relevant studies were selected according to predetermined inclusion and exclusion criteria.
The initial search yielded 3,517 relevant titles and revealed eight different implant neck configurations and/or methods suggested for the preservation of marginal bone. These methods included changes in implant neck length and design, implant surface characteristics, implant diameter, and/or insertion depth; the addition of microthreads; the use of one-piece implants; and the concept of platform switching. After subsequent filtering, 20 studies were finally selected and involved the following methods: the use of microthreads (1 study); modifications in implant surface characteristics (11 studies), implant diameter (4 studies), or insertion depth (2 studies); the use of one-piece implants (3 studies); and platform switching (1 study). Because of the heterogeneity of the studies, it was not possible to analyze the data statistically. No evidence was found regarding the effectiveness of any specific modification in the implant neck area in preserving marginal bone or preventing marginal bone loss.
The current literature provides insufficient evidence about the effectiveness of different implant neck configurations in the preservation of marginal bone. Long-term randomized controlled clinical trials are needed to elucidate the effects of such modifications.
The All-on-Four Treatment Concept: A Systematic Review Patzelt, Sebastian B. M.; Bahat, Oded; Reynolds, Mark A. ...
Clinical implant dentistry and related research,
December 2014, Letnik:
16, Številka:
6
Journal Article
Recenzirano
Purpose
The study aims to evaluate the all‐on‐four treatment concept with regard to survival rates (SRs) of oral implants, applied fixed dental prostheses (FDPs) and temporal changes in proximal bone ...levels.
Materials and Methods
A systematic review of publications in English and German was performed using the electronic bibliographic database MEDLINE, the Cochrane Library, and Google. Hand searches were conducted of the bibliographies of related journals and systematic reviews. The authors performed evaluations of articles independently, as well as data extraction and quality assessment. Data were submitted the weighted least‐squared analysis.
Results
Thirteen (487 initially identified) papers met inclusion criteria. A number of 4,804 implants were initially placed, of which 74 failed, with a majority of failures (74%) within the first 12 months. A total of 1,201 prostheses were incorporated within 48 hours after the surgery. The major prosthetic complication was the fracture of the all‐acrylic FDP. The mean cumulative SR/SR ± (standard deviation) (36 months) of implants and prostheses were 99.0 ± 1.0% and 99.9 ± 0.3%, respectively. The averaged bone loss was 1.3 ± 0.4 mm (36 months). No statistically significant differences were found in outcome measures, when comparing maxillary versus mandibular arches and axially versus tilted placed implants.
Conclusion
The available data provide promising short‐term results for the all‐on‐four treatment approach; however, current evidence is limited by the quality of available studies and the paucity of data on long‐term clinical outcomes of 5 years or greater. In terms of an evidence‐based dentistry, the authors recommend further studies designed as randomized controlled clinical trials and reported according to the CONSORT statement.
The aim of this prospective clinical split-mouth study was to investigate the longterm performance of pressed and computer-aided design/computer-assisted manufacture (CAD/CAM) all-ceramic ...partial-coverage restorations (PCRs). Twentyfive patients were restored with 40 lithium disilicate pressed PCRs (IPS e.max-Press, Ivoclar Vivadent) and 40 leucite-reinforced glass-ceramic CAD/CAM PCRs (ProCAD, Ivoclar Vivadent). All restorations were placed in vital first or second molars. The 7-year Kaplan-Meier survival rate was 100% for pressed PCRs and 97% for CAD/ CAM PCRs. Both systems showed significant deterioration over time in all modified United States Public Health Service criteria. Increased surface roughness and impaired color match were significantly more prevalent with pressed PCRs. Based on the 7-year data, both all-ceramic systems can be considered reliable treatment options for posterior PCRs.
Objective
The aim of this prospective clinical 5-year study was to evaluate the long-term behavior of monolithic computer-aided design and computer-aided manufacturing (CAD/CAM)-fabricated minimally ...invasive polymer-infiltrated ceramic network (PICN) inlays and partial coverage restorations (PCR).
Material and methods
Posterior teeth of 47 patients were restored with 103 restorations (45 inlays, 58 PCRs). After defect-oriented preparations, monolithic PICN restorations of VITA Enamic were fabricated with a CAD/CAM system (inEoS blue/CEREC inLab MCXL) and adhesively bonded (Variolink II). Clinical reevaluations were so far performed at baseline and 6, 12, 24, and 36 months after insertion according to modified United States Public Health Service (USPHS) criteria. Absolute failures were demonstrated by Kaplan-Meier survival rate and relative failures by Kaplan-Meier success rate. A logistic regression model was adjusted for modified USPHS criteria to investigate time and restoration effects (
p
< 0.05).
Results
After an observation time of 3 years, survival rates were 97.4% for inlays and 95.6% for PCRs. Three restorations had to be replaced due to clinically unacceptable fractures. Secondary caries and debonding were not observed. The 3-year Kaplan-Meier success rate was 84.8% for inlays and 82.4% for PCRs. The decrease in marginal adaption (
p
= 0.0005), increase in marginal discoloration (
p
< 0.0001), and surface roughness (
p
= 0.0005) over time were significant. Color match and anatomic form were excellent. No significant differences were found between both types of restorations for survival (
p
= 0.716) and success rate (
p
= 0.431).
Conclusions
Minimally invasive PICN restorations showed a favorable clinical performance over an observation period of 36 months. However, clinical long-term data have to be awaited.
Clinical relevance
PICN restorations are a suitable treatment option for posterior inlays and PCRs.
Objectives: The purpose of this pilot investigation was to test whether zirconia implants restored with different all‐ceramic crowns would fulfill the biomechanical requirements for clinical use. ...Therefore, all‐ceramic Empress®‐1 and Procera® crowns were cemented on zirconia implants and exposed to the artificial mouth. Afterwards, the fracture strength of the all‐ceramic implant–crown systems was evaluated. Conventional titanium implants restored with porcelain‐fused‐to‐metal (PFM) crowns served as controls.
Material and methods: Sixteen titanium implants with 16 PFM crowns and 32 zirconia implants with 16 Empress®‐1 crowns and 16 Procera® crowns each—i.e., three implant–crown groups—were used in this investigation. The titanium implants were fabricated using the ReImplant® system and the zirconia implants using the Celay® system. The upper left central incisor served as a model for the fabrication of the implants and the crowns. Eight samples of each group were submitted to a long‐term load test in the artificial mouth (1.2 million chewing cycles). Subsequently, a fracture strength test was performed with seven of the eight crowns. The remaining eight samples of each group were not submitted to the long‐term load in the artificial mouth but were fracture‐tested immediately. One loaded and one unloaded sample of each group were evaluated regarding the marginal fit of the crowns.
Results: All test samples survived the exposure to the artificial mouth. Three Empress®‐1 crowns showed cracks in the area of the loading steatite ball. The values for the fracture load in the titanium implant–PFM crown group without artificial loading ranged between 420 and 610 N (mean: 531.4 N), between 460 and 570 N (mean: 512.9 N) in the Empress®‐1 crown group, and in the Procera® crown group the values were between 475 and 700 N (mean: 575.7 N) when not loaded artificially. The results when the specimens were loaded artificially with 1.2 million cycles were as follows: the titanium implant–PFM crowns fractured between 440 and 950 N (mean: 668.6 N), the Empress®‐1 crowns between 290 and 550 N (mean: 410.7 N), and the Procera® crowns between 450 and 725 N (mean: 555.5 N). No statistically significant differences could be found among the groups without artificial load. The fracture values for the PFM and the Procera® crowns after artificial loading were statistically significantly higher than that for the loaded Empress®‐1 crowns. There was no significant difference between the PFM crown group and the Procera® group.
Conclusions: Within the limits of this pilot investigation, it seems that zirconia implants restored with the Procera® crowns possibly fulfill the biomechanical requirements for anterior teeth. However, further investigations with larger sample sizes have to confirm these preliminary results. As three Empress®‐1 crowns showed crack development in the loading area of the steatite balls in the artificial mouth, their clinical use on zirconia implants has to be questioned.
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