Ender Kazazoğlu

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.

A Review on Biodentine, a Contemporary Dentine Replacement and Repair Material

Biodentine is a calcium-silicate based material that has drawn attention in recent years and has been advocated to be used in various clinical applications, such as root perforations, apexification, resorptions, retrograde fillings, pulp capping procedures, and dentine replacement. There has been considerable research performed on this material since its launching; however, there is scarce number of review articles that collates information and data obtained from these studies. Therefore, this review article was prepared to provide the reader with a general picture regarding the findings about various characteristics of the material. The results of a PubMed search were classified and presented along with some critical comments where necessary. The review initially focuses on various physical properties of the material with subheadings and continues with biocompatibility. Another section includes the review of studies on Biodentine as a vital pulp treatment material and the article is finalized with the summary of some case reports where the material has been used.

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.

Effects of different surface treatments on stainability of ceramics

STATEMENT OF PROBLEM Final adjustments may result in a loss of ceramic glaze, a situation which must be corrected by reglazing or polishing to obtain clinically successful restorations; such restorations may be susceptible to staining. PURPOSE The purpose of this study was to determine the stainability of ceramics exposed to coffee after different surface treatments and to correlate the surface roughness with the color differences. MATERIAL AND METHODS Sixty-six ceramic (IPS e.maxCeram) disks (15 × 2 mm) were fabricated and glazed according to the manufacturers instructions, then assigned to 6 groups. Group Glaze (Group G), the control, was not subjected to any procedure. All the others were abraded with a diamond rotary cutting instrument. Group Reglaze (Group R) was reglazed; others were polished with different polishing materials; Group Shofu (Group S) was polished with abrasive stone (Dura-Green Stones), coarse silicon polisher (Ceramaster Coarse), silicon polisher (CeraMaster), and polishing paste (Ultra II) with polishing disks (Super-Snap Buff Disks); Group Ultradent (Group U) was polished with 1.0 and 0.5-μm polishing pastes (Ultradent Diamond) with a goat hair brush (Jiffy) and Group Bredent (Group B) was polished with an abrasive stone (Diagen turbo grinder), a round polishing brush (Abraso-fix), and polishing paste (Diamond) with felt wheels. Group Diamond rotary cutting instrument (Group D) was not treated after abrasion with a diamond rotary cutting instrument. Surface roughness was evaluated by profilometer (n=10), and 1 specimen from each group was evaluated by scanning electron microscopy (SEM). Color difference was measured by a spectrophotometer before and after 12 days of immersion in a coffee solution. Data were analyzed by 1-way ANOVA, the Tukey HSD test, and the Pearson rank correlation tests (α=.05). RESULTS The surface roughness (Ra) values were ordered from the highest to the lowest value, which were Group D, B, U, S, R, and G, respectively. Significant differences among groups (P<.01) were found, except for G and R. There were no significant differences between the color difference values of Groups G and R, both of which were significantly lower than the other groups (P<.01). Group D showed the highest ΔE values (>2), which is considered clinically unacceptable (P<.01). No significant differences were found among the S, U, and B groups. There was an 83% positively significant relationship between Ra and ΔE values (P<.01). Rough surfaces stained more after coffee immersion than did smooth surfaces. CONCLUSIONS Surface treatments affected surface roughness and color stability. Smooth surfaces showed better color stability after discoloration. Ceramic staining may be related to surface texture changes after different surface treatments.

Effects of different silanes and acid concentrations on bond strength of brackets to porcelain surfaces

The aim of this study was to determine the optimum silane-coupling agent and the optimum concentration of acid agent when bonding to porcelain surfaces. Eighty deglazed feldspathic porcelain discs with a diameter of 10 mm and a thickness of 2 mm mounted in acrylic resin blocks were randomly divided into four groups. In groups 1 and 2, the porcelain surfaces were etched with 9.6 per cent hydrofluoric (HF) acid and in groups 3 and 4 with 5 per cent HF acid. In groups 1 and 3, the Dynalock maxillary central incisor brackets were bonded with Pulpdent silane and Unite bonding adhesive and in groups 2 and 4 with Reliance silane and Unite. Shear forces were applied to the samples using an Instron universal test machine. The non-parametric Kruskal-Wallis test was used to determine significant differences in bond strengths between the four groups and Dunns multiple comparison test to compare subgroups. The mean bond strengths and standard deviations of groups 1 to 4 were 5.51 +/- 1.19, 6.54 +/- 0.002, 4.55 +/- 1.93, and 6.39 +/- 0.45 MPa, respectively. Specimens bonded with Reliance showed a statistically significantly higher in vitro bond strength than those bonded with Pulpdent. The concentration of etching gels did not result in any statistically significant difference on the in vitro bond strength when evaluated separately.

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.

General health, dental status and perceived dental treatment needs of an elderly population in Istanbul

BACKGROUND Comprehensive data on the oral health status and dental treatment needs of the elderly population in Turkey are deficient. OBJECTIVES This pilot study determined the general and dental health status, perceived medical and dental treatment needs of an elderly population dwelling in residential homes in Istanbul. METHOD Subjects at three different residential homes, namely one belonging to the state and two supported by foundations in Istanbul (N=121, female: 63 and male: 58) were involved in this study. A detailed questionnaire was prepared and dental examinations were conducted. Information was collected related to age, education levels, financial status, current physical functional status, general health, mental health, previous dental history, current dental status, oral hygiene practices and denture hygiene of these elderly people. The prevalence of edentulism, the presence and type of dental prostheses, dental and denture status and denture cleanliness were further evaluated. RESULTS The three most prevalent reported general health problems were associated with genito-urinary problems (24%) followed by cardiovascular (18%) and respiratory problems (14%) varying significantly between genders, with males suffering more from cardiovascular problems than females (p < 0.05). Females showed significantly higher gastrointestinal and orthopaedic problems than males (p < 0.05). Females were more frequently edentulous than males but denture hygiene was significantly better in females than in males (p < 0.05). Brushing frequency did not significantly increase denture hygiene (p = 0.6). More than one-third of the subjects had not been to the dentist within the previous 5-10 years, mainly due to lack of demand, followed by the cost of the dental care and fear. More than two-thirds of denture-wearing subjects wore their dentures only during eating. CONCLUSIONS There was significant perceived dental treatment and care need for the sample population of elderly studied.

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.