The Severity of Human Peri-Implantitis Lesions Correlates with the Level of Submucosal Microbial Dysbiosis

AIM To cross-sectionally analyse the submucosal microbiome of peri-implantitis (PI) lesions at different severity levels. MATERIALS AND METHODS Microbial signatures of 45 submucosal plaque samples from untreated PI lesions obtained from 30 non-smoking, systemically healthy subjects were assessed by 16s sequencing. Linear mixed models were used to identify taxa with differential abundance by probing depth, after correction for age, gender, and multiple samples per subject. Network analyses were performed to identify groups of taxa with mutual occurrence or exclusion. Subsequently, the effects of peri-implant probing depth on submucosal microbial dysbiosis were calculated using the microbial dysbiosis index. RESULTS In total, we identified 337 different taxa in the submucosal microbiome of PI. Total abundance of 12 taxa correlated significantly with increasing probing depth; a significant relationship with lower probing depth was found for 16 taxa. Network analysis identified two mutually exclusive complexes associated with shallow pockets and deeper pockets, respectively. Deeper peri-implant pockets were associated with significantly increased dysbiosis. CONCLUSION Increases in peri-implant pocket depth are associated with substantial changes in the submucosal microbiome and increasing levels of dysbiosis

Polymerization shrinkage kinetics of resin cements

Objective: To contribute to the understanding of the basic shrinkage phenomena exhibited by contemporary resin-cements with varying cure. Methods: Variolink 2 (VL2), Multilink Automix (MA), Multilink Sprint (MS, all Ivoclar-Vivadent), Nexus 2 (NX2), Maxcem (MX, both Kerr) and RelyX Unicem (RX; 3M Espe) were tested for shrinkage-strain VS and shrinkage-stress SZ. MS, MX and RX are self-adhesive; others require additionally etching and bonding. All materials were tested self-cured only (sc) and dual-cured (dc); NX2 and VL2 additionally light-cured only (lc). Light-cure was achieved by a QTH-lamp at circa 500 mW/cm2. VS was measured by the bonded-disk method (Watts and Cash, 1991), SZ by the Bioman device (Watts et al., 2003). Shrinkage-strain and -stress rates with the respective time were calculated. Data were analysed by One-Way ANOVA with Bonferroni's adjustment and T-Test at p<0.05. Results: Ranged from 1.77 to 5.29% for shrinkage-strain and 3.36 to 10.37 MPa for shrinkage-stress. NX2 and VL2 were not significantly different, light-cured only (p>0.05). VS: MX showed the highest VS, RX the lowest, sc as well as dc. When sc, RX initially expanded up to a maximum of <0.5% at t5 min. Dc did generally not result in a higher VS compared to sc. Except for RX, sc and dc varied maximally 0.4%. SZ: The highest stress with sc was exerted by MX, with dc by MS. RX exerted in both groups the lowest stress, whereas no expansion stress was measured. Sc resulted for all materials, except MX, in statistically lower shrinkage-stress values (p<0.05). This is in line with the rate of polymerization, which was for all materials significantly higher by lc and dc than by sc (p<0.001). Significance: Shrinkage data of resin cements are of intrinsic clinical importance. Considering the results of this study, RX represents an alternative to the non-self-adhesive resin cements. As assessed by the pattern of shrinkage-strain, dual-curing is not required for optimal setting, whereas the it leads to higher stresses compared to self-curing. Polymerization-rate and shrinkage-stress development are related to cure mode.Ziel: Das Ziel dieser Studie war, über die Bestimmung von Volumenschrumpfung (VS) und der dabei auftretenden Schrumpfspannung (SZ) zum Verständnis des Polymerisationsvorgangs von Kunststoffzementen in Abhängigkeit von unterschiedlichen Aushärtungsverfahren beizutragen. Materialien und Methodik: Die getesteten Materialien waren Variolink 2 (VL2), Multilink Automix (MA), Multilink Sprint (MS; alle Ivoclar-Vivadent), Nexus 2 (NX2), Maxcem (MX; beide Kerr) and RelyX Unicem (RX; 3M Espe). MX, MS und RX waren selbst-adhäsiv, die anderen, MA, VL2 und NX2, verlangen zur adhäsiven Befestigung zusätzlich Ätzen und Bonden. Alle Materialien wurden selbst-härtend (sc) und dual-härtend (dc) getestet, NX2 und VL2 außerdem licht-härtend allein (lc). Die Photopolymerisation erfolgte mittels einer QTH-Lampe bei einer Intensität von ca. 500 mW/cm2. Die VS wurde nach der Bonded-Disk-Methode gemessen (Watts und Cash, 1991), während zur Bestimmung der SZ der sog. Bioman verwendet wurde (Watts et al., 2003). Daraus wurde anschließend die maximale Schrumpfungsrate mit dem entsprechenden Zeitpunkt des Auftretens errechnet. Die statistische Auswertung erfolgte mittels One-Way Anova (Bonferroni Korrektur) und T-Test bei einem Signifikanzniveau von p<5. Ergebnisse: Die ermittelten Werte lagen zwischen 1,77 und 5,29% für die VS, bzw. zwischen 3,36 und 10,37 MPa für die SZ. Kein signifikanter Unterschied hinsichtlich beider Messwerte wurde zwischen NX2lc und VL2lc gefunden (p>0.05). VS: MX erzielte die höchsten Werte, RX die niedrigsten, sowohl sc als auch dc. Bei sc zeigte RX in der initialen Phase eine Expansion mit einem Maximum von <0.5% bei t5min. Dc führte generell nicht zu signifikant höherer VS als sc. SZ: Sc übt MX die höchste Schrumpfspannung aus, dc ist dies MS. RX erzielt jeweils die niedrigste SZ. Expansionskraft wurde keine festgestellt. Photopolymerisation führt bei allen Materialien, ausgenommen MX, zu signifikant höheren Spannungswerten verglichen mit sc. Dies steht mit der Polymerisationsgeschwindigkeit im Einklang. Diese war bei lc oder dc bei allen Materialien signifikant höher als bei sc (p<0.001). Signifikanz: Die erhobenen Daten dienen der Risikoabschätzung bei der klinischen Anwendung. RX stellt hinsichtlich des Polymerisationsverhaltens eine Alternative zu nicht selbst-adhäsiven Kunststoffzementen dar. Die Art der Polymerisation beeinflusst die Schrumpfspannung wesentlich. Bei Betrachtung der eigentlichen Schrumpfung kann optimale Polymerisation jedoch auch von chemischer Aushärtung allein erwartet werden.eingereicht von Thomas SpinellAbweichender Titel laut Übersetzung der Verfasserin/des VerfassersZusammenfassung in engl. SpracheWien, Med. Univ., Dipl.-Arb., 2008(VLID)171508

Polymerization shrinkage kinetics of dimethacrylate resin-cements

info:eu-repo/semantics/publishe

Circulating endothelial progenitor cells in periodontitis.

BACKGROUND Several biologically plausible mechanisms have been proposed to mediate the association between periodontitis and atherosclerotic vascular disease (AVD), including adverse effects on vascular endothelial function. Circulating endothelial progenitor cells (cEPCs) are known to contribute to vascular repair, but limited data are available regarding the relationship between cEPC levels and periodontitis. The aims of this cross-sectional study are to investigate the levels of hemangioblastic and monocytic cEPCs in patients with periodontitis and periodontally healthy controls and to associate cEPC levels with the extent and severity of periodontitis. METHODS A total of 112 individuals (56 patients with periodontitis and 56 periodontally healthy controls, aged 26 to 65 years; mean age: 43 years) were enrolled. All participants underwent a full-mouth periodontal examination and provided a blood sample. Hemangioblastic cEPCs were assessed using flow cytometry, and monocytic cEPCs were identified using immunohistochemistry in cultured peripheral blood mononuclear cells. cEPC levels were analyzed in the entire sample, as well as in a subset of 50 pairs of patients with periodontitis/periodontally healthy controls, matched with respect to age, sex, and menstrual cycle. RESULTS Levels of hemangioblastic cEPCs were approximately 2.3-fold higher in patients with periodontitis than periodontally healthy controls, after adjustments for age, sex, physical activity, systolic blood pressure, and body mass index (P = 0.001). A non-significant trend for higher levels of monocytic cEPCs in periodontitis was also observed. The levels of hemangioblastic cEPCs were positively associated with the extent of bleeding on probing, probing depth, and clinical attachment loss. Hemangioblastic and monocytic cEPC levels were not correlated (Spearman correlation coefficient 0.03, P = 0.77), suggesting that they represent independent populations of progenitor cells. CONCLUSION These findings further support the notion that oral infections have extraoral effects and document that periodontitis is associated with a mobilization of EPCs from the bone marrow, apparently in response to systemic inflammation and endothelial injury