Journal of Dental Medicine

Background and Aim: In recent years, different substances have been considered in gingival cervical fluid (GCF) as diagnostic markers due to the evaluation of biologic events and biochemical process related to bone turnover during orthodontic movements. IL-6 concentration increases in GCF during the first week after force loading. The aim of this study was to investigate the levels of IL-6 in GCF during orthodontic movements.

Materials and Methods: Fourteen orthodontic patients (9 females and 5 males, mean age 15.1±2.5 years) with Cl I malocclusion needing first bicuspid extraction participated in this clinical trial. In each patient one maxillary canine was distalized (DC) with a NiTi push coil spring. The contra-lateral canine (CC) was included in the orthodontic appliance but was not subjected to the orthodontic force  and one of the mandibular canines was used as control with no orthodontic appliance (Antagonist canine: AC). The concentration of IL-6 was evaluated at the baseline and 14th and 28th days after intervention. GCF was taken with periopapers from both mesial and distal sides of tooth before appliance activation, on the 14th and 28th days. Concentration of IL-6 in DC, CC, and AC detected by ELISA reader was compared by repeated measure ANOVA and LSD multiple comparison, P<0.05 was considered statistically significant.

Results: Although the inflammatory gingival indices increased in both DC and CC teeth but it was not significant. The amount of IL-6 in GCF increased on day 14th in DC teeth in comparison with AC and CC teeth. In addition, the concentration of IL-6 in DC teeth was significantly greater than the 1st and 28th days. The maximum concentration of IL-6 was detected in both pressure and tension sides of DCs at T₁₄. At T₂₈, although the IL-6 levels were significantly higher than baseline levels but, it was significantly less than T₁₄.

Conclusion: The results of this study support the hypothesis that mechanical stimuli cause an inflammatory reaction within the periodontal tissues.

Background and Aims: In this in-vitro study, the effect of multiple adhesive coating on the microshear bond strength of composite to dentin and surface microhardness of dentin after treatment with four adhesives (One Step Plus, One Step, Single Bond, Single Bond 2) were evaluated.

Materials and Methods: One hundred intact human molars were cut to obtain disks of dentin having 2 mm thickness. For the microshear bond test, sixty disks were randomly divided into four groups. In each group one type of adhesive was used. In one half of a disk two layers and in another half six layers of adhesive were applied. Cylinders with 1mm height was filled with a composite and light cured. The cross-head speed was 0.5 mm/min. Vickers microhardness was tested on forty dentin disks which divided into four groups and prepared in the same manner used for microshear bond test. Data were analyzed by Two-way ANOVA and Tukey tests.

Results: The highest and lowest bond strength were recorded as 29.49 ± 5.74 MPa (One Step Plus 6 layers), and 21.23 ± 4.83 MPa (One Step Plus 2 layers), respectively. The results indicated that One Step Plus bond strength in 6 Layers was significantly higher than 2 layers. The highest and lowest dentin hardness values were
39.08 ± 8.34VHN (Single Bond 2 layers) and 28.53 ± 5.98 VHN (One Step Plus 6 layers). None of the adhesives exhibited significant difference in hardness with regards to the layers applied (P>0.05). Presence of filler in adhesives had no significant effect on bond strength (P=0.05) whereas caused significant decrease in the dentin microhardness (P<0.05). In addition, type of solvent had significant effect on the bond strength and bond strength was significantly higher in acetone-base adhesives (P<0.05). However, dentin microhardness was significantly higher in the ethanol-base adhesives (P<0.05).

Conclusion: Multiple adhesive coating had no influence on the microshear bond strength of composite to dentin and dentin surface microhardness. It was dependent on the type of adhesive used.