STATEMENT OF THE PROBLEM: All-ceramic post-and-core restorations offer a number of advantages compared with systems that use metal build-ups. In certain clinical cases, however, fractures at the joint between the post and core build-up have been reported. PURPOSE: The objective, therefore, is to improve the joint between the post and the core build-up. MATERIAL AND METHODS: Three different methods were used to prepare all-ceramic post-andcore restorations; pressing IPS Empress core build-ups to CosmoPost zirconia posts, cementing IPS Empress core build-ups to CosmoPost zirconia posts and Celay-milling of zirconia blanks. A series of ten restorations was prepared for each of the three methods. The post-and-core complexes were tested to failure with the load applied perpendicular to the post axis. The load and deflection at fracture were recorded. RESULTS: The highest breaking load and highest deflection were recorded for the cementing technique with values of 25.3 N and 394 micrometer, respectively. The corresponding values for the pressed core build-ups and the milled zirconia core build-ups were 22 N and 301 micrometer, and 13 N and 160 micrometer, respectively. All the differences are statistically significant (p=0.05). Regarding the load-dependence of the deflection, the cemented core build-ups again demonstrated the highest value with 15.5 micrometer/N. The difference in the values of 13.6 micrometer/N and 13 micrometer/N recorded for the pressed-on and milled core build-ups, respectively, were statistically insignificant. CONCLUSION: In regard to the high fracture resistance of zirconia post, adhesive cementing the core build-up to the post offers a viable alternative to the conventional pressing technique. The elastic bond between the rigid high-strength zirconia post and the core build-up presents an additional advantage.
Adhesives ; Axis, Cervical Vertebra ; Joints

PURPOSE: This in-vitro study was designed to evaluate retention forces, microleakage and plastic deformation of a prefabricated 2-implant bar attachment system (SFI-Bar, Cendres+Metaux, Switzerland). MATERIALS AND METHODS: Two SFI implant-adapters were torqued with 35 Ncm into two implant analogues. Before the tube bars were finally sealed, the inner cavity of the tube bar was filled with liquid red dye to evaluate microleakage. As tube bar sealing agents three different materials were used (AGC Cem (AGC, resin based), Cervitec Plus (CP; varnish) and Gapseal (GS; silicone based). Four groups with eight specimens each were tested (GS, GS+AGC, AGC, CP). For cyclic loading, the attachment system was assembled parallel to the female counterparts in a chewing simulator. The mean retention forces of the initial and final ten cycles were statistically evaluated (ANOVA, alpha< or =.05). RESULTS: All groups showed a significant loss of retention forces. Their means differed between 30-39 N initially and 22-28 N after 50,000 loading cycles. No significant statistical differences could be found between the groups at the beginning (P=.224), at the end (P=.257) or between the loss of retention forces (P=.288). Microleakage occurred initially only in some groups but after 10,000 loading cycles all groups exhibited microleakage. CONCLUSION: Long-term retention forces of the SFI-Bar remained above 20 N which can be considered clinically sufficient. The sealing agents in this study are not suitable to prevent microleakage.
Female ; Humans ; Mastication ; Plastics* ; Silicones

The composition of the gut microbiota is linked to multiple diseases,including Parkin-son's disease(PD).Abundance of bacteria producing short-chain fatty acids(SCFAs)and fecal SCFA concentrations are reduced in PD.SCFAs exert various beneficial functions in humans.In the interventional,monocentric,open-label clinical trial"Effects of Resistant Starch on Bowel Habits,Short Chain Fatty Acids and Gut Microbiota in Parkinson's Disease"(RESISTA-PD;ID:NCT02784145),we aimed at altering fecal SCFAs by an 8-week prebiotic intervention with resistant starch(RS).We enrolled 87 subjects in three study-arms:32 PD patients received RS(PD+RS),30 control subjects received RS,and 25 PD patients received solely dietary instructions.We performed paired-end 100 bp length metagenomic sequencing of fecal samples using the BGISEQ platform at an average of 9.9 GB.RS was well-tolerated.In the PD+RS group,fecal butyrate concentrations increased significantly,and fecal calprotectin concentrations dropped significantly after 8 weeks of RS intervention.Clinically,we observed a reduction in non-motor symptom load in the PD+RS group.The reference-based analysis of metagenomes highlighted stable alpha-diversity and beta-diversity across the three groups,including bacteria producing SCFAs.Reference-free analysis suggested punctual,yet pronounced differences in the metagenomic signature in the PD+RS group.RESISTA-PD highlights that a prebiotic treatment with RS is safe and well-tolerated in PD.The stable alpha-diversity and beta-diversity alongside altered fecal butyrate and calprotectin concentrations call for long-term studies,also investigating whether RS is able to modify the clinical course of PD.