[Effects of different orthodontic treatments on sputum chemokines CX3CL1, RANKL/OPG levels in patients with malocclusion].

PURPOSE: To investigate the effects of different orthodontic treatments on gingival crevicular fluid chemokine CX3CL1, nuclear factor κB receptor activating factor ligand/osteoprotegerin(RANKL/OPG) levels in patients with malocclusion. METHODS: Ninety-six patients with malocclusion who were scheduled to undergo orthodontic treatment were randomly divided into four groups. All patients were treated with square wire appliance, and 0, 50, 150, 250 g of far-distal orthodontic force were given respectively. The levels of CX3CL1 and RANKL/OPG in gingival crevicular fluid were detected in four groups after 1, 2, 3, and 4 weeks of treatment. SPSS 25.0 software package was used for statistical analysis of the date. RESULTS: The levels of CX3CL1, RANKL and RANKL/OPG in the gingival crevicular fluid of the four groups were continuously increased after treatment for 1-3 weeks, and decreased after 4 weeks of treatment (P<0.05). The OPG in the gingival crevicular fluid was at a low level after 1-3 weeks of treatment. There was an increase after 4 weeks of treatment (P<0.05). The levels of CX3CL1, RANKL, OPG and RANKL/OPG in gingival crevicular fluid increased gradually in group A, B, C and D (P<0.05), and the differences between the groups were statistically significant (P<0.05). CONCLUSIONS: The levels of CX3CL1 and RANKL/OPG in gingival crevicular fluid are closely related to orthodontic force and treatment time, and can be used as an index to evaluate orthodontic treatment of alveolar bone remodeling.

[Effects of different die materials on fracture and failure behaviors of all-ceramic crowns].

OBJECTIVE: To investigate the influence of different die materials on fracture strength and failure mode of IPS e.max Press crowns in mechanical test. METHODS: Thirty-six IPS e.max Press crowns were divided into 3 groups. They were cemented to extracted maxillary first premolars in Group 1, to epoxy dies in Group 2, and to porous NiTi alloy dies in Group 3 respectively. All the crowns were subjected to compressive load in an universal mechanical testing machine. The maximum fracture strength(N) was recorded and fracture modes of the tested crowns were classified. Fractographies of the failed crowns were observed with a stereomicroscope. RESULTS: Statistical analysis results showed that the mean fracture strength of the IPS e.max Press crowns on extracted natural teeth [(1159.7 +/- 256.0) N] and porous NiTi alloy dies [(1229.6 +/- 326.7) N] were obviously higher than that of epoxy dies [(883.5 +/- 198.1) N, P = 0.016 and 0.003]. Observations of the fractographies of failed crowns showed that the crowns on epoxy die fractured mesio-distally and no plastic deformation and characteristic cracks were observed. However, crowns in the other groups showed cone cracks at the contact area on occlusal surface and radical cracks initiated from the adhesive interfaces. CONCLUSIONS: Die material has a significant influence on fracture resistance and fracture mode of the IPS e.max Press crowns. The crowns cemented to porous NiTi alloy dies show a similar fracture mode as those on extracted natural teeth.