METHODS: Six master dies were duplicated from the prepared maxillary first premolar tooth using nonprecious metal alloy (Wiron 99). Thirty copings (Procera AllCeram) of 0.6-mm thickness were manufactured. Three types of luting media were used: zinc phosphate cement (Elite), glass ionomer cement (Fuji I), and dual-cured composite resin cement (Panavia F). Ten copings were cemented with each type. Two master dies were used for each group, and each of them was used to lute five copings. All groups were cemented according to manufacturer's instructions and received a static load of 5 kg during cementation. After 24 hours of distilled water storage at 37 degrees C, the copings were vertically compressed using a universal testing machine at a crosshead speed of 1 mm/min.
RESULTS: ANOVA revealed significant differences in the load at fracture among the three groups (p < 0.001). The fracture strength results showed that the mean fracture strength of zinc phosphate cement (Elite), glass ionomer cement (Fuji I), and resin luting cement (Panavia F) were 1091.9 N, 784.8 N, and 1953.5 N, respectively.
CONCLUSION: Different luting agents have an influence on the fracture resistance of Procera AllCeram copings.
METHODS: This study included 3 groups with 15 orthodontic patients in each. The control group included patients who had no probiotic treatment, the subjects in the kefir group consumed 2 × 100 ml of kefir (Atatürk Orman Ciftligi, Ankara, Turkey) per day, and the subjects in the toothpaste group brushed their teeth with toothpaste with probiotic content (GD toothpaste; Dental Asia Manufacturing, Shah Alam, Selangor, Malaysia) twice a day. Samples were collected at 3 times: beginning of the study, 3 weeks later, and 6 weeks later. The salivary flow rate, buffer capacity, and Streptococcus mutans and Lactobacillus levels in the saliva were evaluated. Chair-side kits were used to determine the S mutans and Lactobacillus levels.
RESULTS: A statistically significant decrease was observed in the salivary S mutans and Lactobacillus levels in the kefir and toothpaste groups compared with the control group (P <0.05). A statistically significant increase was observed in the toothpaste group compared with the control and kefir groups in buffer capacity. Changes in the salivary flow rate were not statistically significant.
CONCLUSIONS: The regular use of probiotics during fixed orthodontic treatment reduces the S mutans and Lactobacillus levels in the saliva.
METHODS: Different volume percentages of HEMA were tested in four experimental silane-based primer solutions (additions of HEMA: 0, 5.0 vol%, 25.0 vol% and 50.0 vol%). An experimental silane blend (primer) of 1.0 vol% 3-isocyanatopropyltrimethoxysilane (ICMS) + 0.5% bis-1,2-(triethoxysilyl) ethane (BTSE) was prepared and used. The experimental primers together with the control group were applied onto acid-etched premolars for attachment of orthodontic brackets. After artificial aging by thermocycling the shear-bond strength was measured. The fractured surfaces of all specimens were examined under scanning electron microscopy (SEM) to evaluate the failure mode on the enamel surface.
RESULTS: The experimental primers showed the highest shear-bond strength of 21.15 MPa (SD ± 2.70 MPa) and with 25 vol% showed a highly significant increase (P < 0.05) in bond strength. The SEM images showed full penetration of adhesive agents when using silane-based primers. In addition, the SEM images suggested that the predominant failure type was not necessarily the same as for the failure propagation.
CONCLUSIONS: This preliminary study suggested that nonacidic silane-based primers with HEMA addition might be an alternative to for use as adhesion promoting primers.