Zirconia Primers Improve the Shear Bond Strength of Dental Zirconia.

PURPOSE: Various resin cements and priming agents are available for adhesive luting of zirconia restorations. The purpose of this study was to investigate how cement type and priming protocol affect the shear bond strength on zirconia ceramics. MATERIALS AND METHODS: Yttria-stabilized tetragonal zirconia polycrystalline ceramic cylinders were bonded to flat zirconia ceramic surfaces using 7 commercially available resin cements. Ten specimens of each cement group were pretreated with a universal primer, and 10 specimens per group were bonded without pretreatment. In addition, 10 specimens per group were pretreated with system-specific zirconia primers, which were available for 3 cements. Altogether, 170 bonded specimens were water-stored, thermal-cycled, and then submitted to shear bond strength tests. The shear bond strength and the fracture types were documented. Differences in shear bond strengths were assessed using 2-way ANOVA with post-hoc test (α = 0.05). A point-biserial correlation was run between the fracture patterns and the shear bond strengths. RESULTS: The mean shear bond strengths of cements in the unprimed group showed large variations between 2.52 ± 3.01 (mean ± SD) MPa and 33.15 ± 7.35 MPa. Pretreating the specimens with a universal primer improved the shear bond strengths significantly in all groups (p < 0.05) with a range of 21.80 ± 12.51 to 57.20 ± 11.40 MPa. The system-specific primers also improved the shear bond strength significantly, compared to the unprimed group (p < 0.01); however, only one system-specific primer achieved a shear bond strength superior to the universal primer (p < 0.01). There was also a statistical correlation between the fracture type and the shear bond strength (p < 0.0005), with cohesively fractured specimens showing higher shear bond strengths (37.24 ± 19.87 MPa) than adhesively fractured specimens (23.10 ± 17.65 MPa) (p < 0.001). CONCLUSION: Using universal primer can enhance the maximal shear bond strength of zirconia.

Periodontal Ehlers-Danlos Syndrome Is Caused by Mutations in C1R and C1S, which Encode Subcomponents C1r and C1s of Complement.

Periodontal Ehlers-Danlos syndrome (pEDS) is an autosomal-dominant disorder characterized by early-onset periodontitis leading to premature loss of teeth, joint hypermobility, and mild skin findings. A locus was mapped to an approximately 5.8 Mb region at 12p13.1 but no candidate gene was identified. In an international consortium we recruited 19 independent families comprising 107 individuals with pEDS to identify the locus, characterize the clinical details in those with defined genetic causes, and try to understand the physiological basis of the condition. In 17 of these families, we identified heterozygous missense or in-frame insertion/deletion mutations in C1R (15 families) or C1S (2 families), contiguous genes in the mapped locus that encode subunits C1r and C1s of the first component of the classical complement pathway. These two proteins form a heterotetramer that then combines with six C1q subunits. Pathogenic variants involve the subunit interfaces or inter-domain hinges of C1r and C1s and are associated with intracellular retention and mild endoplasmic reticulum enlargement. Clinical features of affected individuals in these families include rapidly progressing periodontitis with onset in the teens or childhood, a previously unrecognized lack of attached gingiva, pretibial hyperpigmentation, skin and vascular fragility, easy bruising, and variable musculoskeletal symptoms. Our findings open a connection between the inflammatory classical complement pathway and connective tissue homeostasis.

Adjusting dental ceramics: An in vitro evaluation of the ability of various ceramic polishing kits to mimic glazed dental ceramic surface.

STATEMENT OF PROBLEM: During the insertion appointment, the practitioner is often faced with the need to adjust ceramic surfaces to fit a restoration to the adjacent or opposing dentition and soft tissues. PURPOSE: The purpose of this study was to assess the ceramic surface smoothness achieved with various commercially available ceramic polishing kits on different commonly used ceramic systems. The reliability of the cost of a polishing kit as an indicator of improved surface smoothness was assessed. MATERIAL AND METHODS: A total of 350 ceramic surfaces representing 5 commonly available ceramic systems (IPS Empress Esthetic, IPS e.max Press, Cergo Kiss, Vita PM 9, Imagine PressX) were treated with 5 types of ceramic polishing systems (Cerapreshine, 94006C, Ceramiste, Optrafine, Zenostar) by following the manufacturers' guidelines. The surface roughness was measured with a profilometer (Taylor Hobson; Precision Taylor Hobson Ltd). The effects of ceramic systems and polishing kits of interest on surface roughness were analyzed by 2-way ANOVA, paired t test, and Bonferroni corrected significance level. RESULTS: The ceramic systems and polishing kits statistically affected surface roughness (P<.001).The polishing kit Zenostar on IPS e.max Press created the smoothest ceramic surface. No correlation could be established between the high cost of the polishing kit and low surface roughness. None of the commonly used ceramic polishing kits could create a surface smoother than that of glazed ceramic (P<.001). CONCLUSIONS: The inclusion of a diamond polishing paste step is recommended to improve surface smoothness (P<.001). The cost of ceramic polishing kits is not recommended as a reliable indicator of better performance of ceramic polishing kits (P>.30).