Zeynep Özkurt

Zirconia Dental Implants: A Literature Review

Titanium and titanium alloys are widely used for fabrication of dental implants. Because of potential immunologic and possible esthetic compromises with titanium implants, novel implant technologies are being developed. However, these novel technologies must maintain the characteristics that provide titanium implants with their high success rates. Zirconia implants were introduced into dental implantology as an alternative to titanium implants. Zirconia seems to be a suitable implant material because of its toothlike color, mechanical properties, biocompatibility, and low plaque affinity. The aim of this study is to review clinical and research articles conducted on zirconia dental implants, compare them with titanium dental implants, and provide information on zirconia dental implant osseointegration and mechanical strength. Zirconia dental implants have the potential to become alternative dental implants to titanium dental implants, but they are not yet in routine clinical use.

Clinical Success of Zirconia in Dental Applications

The application of ceramic materials for the fabrication of dental restorations is a focus of interest in esthetic dentistry. The ceramic materials of choice are glass ceramics, spinel, alumina, and zirconia. Zirconia was introduced into dentistry in the 1990s because of its good mechanical and chemical properties and is currently being used as a material for frameworks, dowels, implants, abutments, and orthodontic brackets. Many in vitro studies about zirconia use have been published, but clinical long-term studies are very important. This article presents data regarding the incidence of clinical success and complications of zirconia in these dental applications. Clinical studies published to date seem to indicate that zirconia is well tolerated and sufficiently resistant.

Shear Bond Strength of Resin Cement to Zirconia Ceramic After Aluminum Oxide Sandblasting and Various Laser Treatments

OBJECTIVE The aim of this study was to evaluate the effect of different surface treatments; sandblasting, Er:YAG, Nd:YAG, or CO(2) laser irradiation on the shear bond strength (SBS) of zirconia ceramic to dentin. BACKGROUND DATA Zirconia is not properly luted with resin cements. Various surface treatment methods have been suggested for zirconia to obtain high bond strength to resin cements. There is no study that compared the effect of different laser types (Er:YAG, Nd:YAG, CO(2)) with sandblasting on SBS between zirconia and dentin. METHODS One hundred and twenty human maxillary third molar teeth were sectioned 3 mm below the occlusal surfaces, embedded in a metal ring with autopolymerizing acrylic resin, and stored in distilled water at 37(0)C. One hundred and twenty disc-shaped zirconia specimens were fabricated (6 mm in diameter and 4 mm in thickness), and randomly assigned to six groups (n=20): Group 1, untreated (control); Group 2, sandblasted; Group 3, Er:YAG laser irradiated; Group 4, Nd:YAG laser irradiated with contact; Group 5, Nd:YAG laser irradiated with non-contact; Group 6, CO(2) laser irradiated. They were cemented onto the dentin with dual-cured resin cement (Variolink(®)). After they were stored in distilled water at 37(0)C for 24 h, the SBS test was performed at a crosshead speed of 1 mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. RESULTS Results of this study did not show statistically significant differences between Groups 1 and 2, or among Groups 3, 4 and 5. The lowest SBS was recorded in Group 6 (CO(2) laser), and the highest SBS was recorded in Group 4 (Nd:YAG laser with contact), followed by Group 3 (Er:YAG laser). The adhesive failure mode was predominantly observed in Groups 2, 3, 5, and 6. Group 1 showed 45% mixed failure and Group 4 showed 50% mixed failure. CONCLUSIONS This study shows that Er:YAG and Nd:YAG laser treatment increased the bond strength of zirconia compared to sandbasting and CO(2) laser treatment.

Comparison of different grinding procedures on the flexural strength of zirconia

STATEMENT OF PROBLEM The surface of zirconia ceramic is damaged during grinding, which may affect the mechanical properties of the material. PURPOSE The purpose of this study was to compare the biaxial flexural strength of zirconia after different grinding procedures and to measure the temperature rise from grinding. MATERIAL AND METHODS Forty disk-shaped zirconia specimens (15 × 1.2 mm) with a smaller disk in the center of each disk (1 × 3 mm) were divided into 4 groups (n=10). The specimens were ground with a high-speed handpiece and micromotor with 2 different grinding protocols, continual grinding and periodic grinding (10 seconds grinding with 10 seconds duration), until the smaller disk was removed. Control specimens without the center disk (n=10) were analyzed without grinding. The biaxial flexural strengths of the disks were determined in a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture strength (MPa) was recorded, and the results were analyzed using a 1-way ANOVA, Tukey HSD test, Students t test, and Pearson correlation test (α=05). RESULTS All grinding procedures significantly decreased flexural strength (P<.01). The mean flexural strength of the high-speed handpiece groups was higher (815 MPa) than that of the micromotor groups (718 MPa). The temperature values obtained from micromotor grinding (127°C) were significantly higher than those from high-speed handpiece grinding (63°C) (P<.01). CONCLUSIONS Grinding zirconia decreased flexural strength. Zirconia material ground with a high-speed handpiece run continually caused the least reduction in flexural strength.

Shear bond strength of luting agents to fixed prosthodontic restorative core materials

BACKGROUND Bonding properties of luting cements are important for retention of restorative core materials. The aim of this study was to compare the bonding performance of a resin-modified glass ionomer cement and a self-adhesive resin cement to various fixed prosthodontic core materials. METHODS Cylindrical specimens with a thickness of 2 mm and a diameter of 5 mm were fabricated from Au-Pd-Ag, Co-Cr, Ni-Cr-Mo, Ni-Cr-Fe alloys, titanium, zirconia and Empress II (n = 20). Each group was divided into two subgroups to be luted with two different luting agents. Composite resin blocks were cemented onto specimens with RelyXUnicem and FujiCem. A shear bond strength machine with 50 kg load cell and 0.50 mm/min crosshead speed was used. Kruskal Wallis test, Dunns Multiple Range test and Mann-Whitney-U test were used for statistical analysis. The results were evaluated in a confidence interval of p < 0.05. RESULTS The highest bond strength was obtained between Ni-Cr-Fe-RelyXUnicem (8.22 +/- 2.15 MPa) and the lowest was between Empress II-FujiCem (1.48 +/- 0.9 MPa). In FujiCem groups, Co-Cr and Ni-Cr-Fe showed significantly higher bond strength than Au-Pd-Ag and Empress II. In RelyX Unicem groups, Ni-Cr-Fe showed higher bond strength than Empress II. CONCLUSIONS The types of luting agents and restorative core materials may have a significant influence on bond strength.

Influence of Grinding Procedures on the Flexural Strength of Zirconia Ceramics

The surface of zirconia may be damaged during grinding, influencing the mechanical properties of the material. The purpose of this study was to compare the flexural strength of zirconia after different grinding procedures. Twenty bar-type zirconia specimens (21 x 5 x 2 mm) were divided into 4 groups and ground using a high-speed handpiece or a low-speed straight handpiece until the bars were reduced 1 mm using two different grinding times: continuous grinding and short-time grinding (n=5). Control specimens (n=5) were analyzed without grinding. The flexural strengths of the bars were determined by using 3-point bending test in a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture load (N) was recorded, and the data were analyzed statistically by the Kruskal Wallis test at a significance level of 0.05. In the test groups, high-speed handpiece grinding for a short time had produced the highest mean flexural strength (878.5 ± 194.8 MPa), while micromotor continuous grinding produced the lowest mean flexural strength (733.8 ± 94.2 MPa). The control group was the strongest group (928.4 ± 186.5 MPa). However, there was no statistically significant differences among the groups (p>0.05). Within the limitations of the study, there was no difference in flexural strength of zirconia specimens ground with different procedures.

Clinical management of a fractured anterior tooth with reattachment technique: a case report with an 8-year follow up.

Fracture of anterior teeth is a relatively common outcome of trauma to the teeth. If the fractured teeth fragments are recovered by the patient and brought to the dental office within reasonable time, the fragments may be reattached to the remaining tooth structure. This article presents a case of a 15-year-old male patient with fractured left maxillary lateral incisor. The fragment reattachment was performed using dual-cured composite resin cement and the treatment outcomes of an 8-year follow up were presented. The technique described in this case report for reattachment of the fractured fragments is simple, while restoring providing long-lasting esthetics and improved function with a very conservative approach.

Effect of Er:YAG laser on debonding strength of laminate veneers

Objective: The purpose of this study was to evaluate the debonding strength of laminate veneers after using erbium-doped: yttrium aluminium garnet (Er:YAG) laser. Materials and Methods: A total of 60 bovine mandibular incisor teeth were divided into two groups (n = 30). Cylindrical specimens (0.7 mm × 5 mm) were fabricated from Empress II ceramic. Then, they were cemented to incisors using dual-cured resin cement (Variolink II). In the first group, no laser application was performed. The Er:YAG laser was applied on each laminate veneer at the test group for 9 s by using the scanning method. Shear force to remove the laminate veneers were applied with universal testing machine at a crosshead speed of 1 mm/min. Results: Results of this study exhibited significant differences between the control (27.28 ± 2.24 MPa) and test group (3.44 ± 0.69 MPa) (P < 0.05). Conclusion: This study shows that application of Er:YAG laser decreased the bond strength of laminate veneers.

In Vitro Comparison of Fracture Strength of Experimental Hollow and Solid Design Zirconia Dowels

PURPOSE The aim of this study was to evaluate the fracture strength of experimental hollow and solid design zirconia dowels. MATERIALS AND METHODS Three types of dowels (fiber-reinforced composite [FRC], hollow design, and solid design zirconia dowels) were tested in the study (n = 10). A three-point bending method was conducted, and a load was applied until fracture. The values were recorded as Newtons (N) and then converted to megapascals (MPa) according to the diameter of the dowels. Statistical analyses were performed using one-way ANOVA and Tukey HSD tests. The significance was set at p < 0.05. RESULTS The mean fracture strength of the hollow design zirconia dowels was significantly higher (960.72 MPa) than solid zirconia dowels (741.78 MPa) and FRC dowels (687.64 MPa) (p < 0.05). CONCLUSIONS The hollow design zirconia dowel seems to have sufficient fracture strength for anterior restorations. This design may be beneficial to access the apical region when retreatment is necessary, without any dowel-removing procedure.

Reconstruction of edentulous maxillary and mandibular arches with implant-supported fixed restorations using a digital treatment planning technique: a clinical report.

This article reports on the treatment of edentulous maxillary and mandibular arches with implant-supported fixed partial dentures. Treatment planning and surgical and restorative techniques are reviewed. Preoperative computerized tomography was obtained and computer software was used to determine the final position of the implants and restorations. The outcome has been favorable both for the patient and the clinicians.