Implant-supported metal-ceramic and resin-modified ceramic crowns: A 5-year prospective clinical study.

STATEMENT OF PROBLEM: Because of market demand for innovation, new restoration materials have been introduced without adequate testing; clinical failure may be the consequence, and clinical studies are needed. PURPOSE: The purpose of this clinical study was to evaluate the biological and mechanical clinical behavior of implant-supported resin-modified ceramic crowns compared with that of metal-ceramic crowns. MATERIAL AND METHODS: Forty-two participants aged between 35 and 65 years received single implants in posterior edentulous sites. After the osseointegration period, half of the implants (selected randomly) (n=25) were restored with metal-ceramic crowns (MC group) and the other half with resin-modified ceramic crowns (RMC group) bonded with dual-polymerized resin cement onto titanium abutments. The biomechanical state of the restorations and implants was analyzed. RESULTS: Mean peri-implant bone loss after 5 years of functional life was 0.3 ±0.6 mm. The implant clinical survival rate was 98%. RMC crowns had a survival rate of 70%, whereas MC crowns had a 100% survival rate. RMC crowns had more mechanical complications than the MC group (P<.001). Peri-implant bone loss showed no significant differences between crown type (P=.175). CONCLUSIONS: All peri-implant bone loss values were within the range considered acceptable. Metal-ceramic crowns showed better mechanical behavior than resin-modified ceramic crowns. Biological responses of peri-implant tissue would appear to be independent of the type of cemented crown.

Polylactic Acid as a Material for Three-Dimensional Printing of Provisional Restorations.

PURPOSE: To assess the marginal fit of provisional polylactic acid (PLA) crowns obtained via three-dimensional (3D) printing using a profile projector. MATERIALS AND METHODS: A stone cast was scanned, and 15 provisional dental crowns were designed and printed in PLA using a 0.2-mm nozzle and 135-degree build angle. The marginal fit was measured at six points on each crown using a profile projector. RESULTS AND CONCLUSION: Within the limitations of this study, the marginal fit of PLA provisional restorations was clinically acceptable, and the results were comparable to those observed with polymethyl methacrylate provisional restorations.

Electrochemical Behaviour and Galvanic Effects of Titanium Implants Coupled to Metallic Suprastructures in Artificial Saliva.

The aim of the present study is to analyze the electrochemical behavior of five different dental alloys: two cobalt-chromium alloys (CoCr and CoCr-c), one nickel-chromium-titanium alloy (NiCrTi), one gold-palladium alloy (Au), and one titanium alloy (Ti6Al4V), and the galvanic effect when they are coupled to titanium implants (TiG2). It was carried out by electrochemical techniques (open circuit measurements, potentiodynamic curves and Zero-Resistance Ammetry) in artificial saliva (AS), with and without fluorides in different acidic conditions. The studied alloys are spontaneously passivated, but NiCrTi alloy has a very narrow passive domain and losses its passivity in presence of fluorides, so is not considered as a good option for implant superstructures. Variations of pH from 6.5 to 3 in artificial saliva do not change the electrochemical behavior of Ti, Ti6Al4V, and CoCr alloys, and couples, but when the pH of the artificial saliva is below 3.5 and the fluoride content is 1000 ppm Ti and Ti6Al4V starts actively dissolving, and CoCr-c superstructures coupled to Ti show acceleration of corrosion due to galvanic effects. Thus, NiCrTi is not recommended for implant superstructures because of risk of Ni ion release to the body, and fluorides should be avoided in acidic media because Ti, Ti6Al4V, and CoCr-c superstructures show galvanic corrosion. The best combinations are Ti/Ti6Al4V and Ti/CoCr as alternative of noble gold alloys.

Study of surface topography, roughness, and microleakage after dental preparation with different instrumentation.

PURPOSE: The purpose of this study was to compare the differences in surface characteristics and roughness of teeth finished for porcelain veneer laminates using different instrumentation and to assess their influence on microleakage. MATERIALS AND METHODS: Fifty-six extracted human maxillary central incisors were divided randomly into two groups: Group HsR teeth were finished with a high-speed handpiece with diamond burs; group SO teeth were finished with a sonic oscillating diamond instrument. Porcelain veneers were bonded to 24 teeth in each group. Microleakage was measured in the cervical area. Four remaining teeth in each group were examined using confocal laser-scanning microscopy and scanning electron microscopy. RESULTS: Oscillating instruments produced a rougher dentinal surface (Ra values; P = .029) than those finished with high-speed rotary technology. CONCLUSIONS: There is less microleakage when bonded restoration edges are situated over dentin that has been finished with sonic oscillating instrumentation (P = .006).

A clinical longitudinal study 323 porcelain laminate veneers. Period of study from 3 to 11 years.

OBJECTIVE: The objective of this study was to evaluate the clinical results of 323 porcelain laminate veneers over a period of 3 to 11 years. MATERIAL AND METHOD: This study included 70 patients, aged between 18 and 74 years. Of the 323 total veneers, 124 were of a simple design and 199 were of a functional design. The condition of the soft tissues and hygiene, in addition to the condition of the abutment teeth, the restorations and patient satisfaction were all clinically examined. In carrying out the statistical analysis, a descriptive approach was taken in analyzing the data. The Kaplan Meier method was used for statistically analyzing the survival rates of the porcelain laminate veneers. RESULTS: Analysis of the soft tissue revealed marginal recession in 7.7% of the cases, and in 21.6% of the cases, bleeding was detected on probing. Analysis of the condition of the abutment teeth revealed secondary caries and hypersensitivity in 3.1% of the cases, and changes in pulp vitality were observed in 2.8% of the cases. In studying the condition of the restorations, marginal integrity was observed to be excellent in 98% of the cases, slight marginal pigmentation was present in 39.3% of the cases, fractures were present in 4% of the cases and decementation in 9% of the cases. The degree of patient satisfaction was considered to be excellent in 97.1% of the cases. CONCLUSIONS: Porcelain laminate veneers are a predicable treatment option that offer excellent results.

Full maxillary rehabilitation with an all-ceramic system.

With the appearance of all-ceramic systems, providing a choice of framework porcelains and allowing the same material to be used for the veneer, it is now possible to select the ideal structure in terms of both function and aesthetics. Silicate ceramics allow porcelain laminate veneers and crowns to be used in the anterior region, providing excellent aesthetics; while for the posterior area, where function takes precedence, oxide ceramics, specifically zirconium oxide, are preferred. The IPS e.max ceramic system, heir-apparent to the IPS Empress 2 system, combines the advantages of zirconium oxide ceramics (IPS e.max Zircad) with the excellent aesthetic qualities of silicate ceramics (IPS e.max Press). This paper presents a clinical case requiring complete maxillary rehabilitation for aesthetic purposes. An overview of some of the porcelains used in this system, analyzed from both the clinical and laboratory perspective is provided. The aesthetic advantages of a single ceramic veneer, the need to select appropriate ceramics for anterior and posterior regions, and cementation and surface treatments are discussed.