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Abstract Background Achieving sufficient professional mechanical biofilm removal (PMPR) can be challenging in supportive periodontal therapy (SPT), particularly in patients with prosthetic restorations. This experimental study aimed to simulate five years of SPT with periodic PMPR near the luting gap of ceramic restorations using a rubber cup with polishing paste (RCP), air polishing with two different low-abrasive powders (LAPA-1: glycine powder, LAPA-2: erythritol powder), and non-professional mechanical cleaning (control group) to measure the extent of volume loss in the luting gap after baseline (∆V = Vbaseline-V1-5; in µm3). Methods Two operators randomly performed PMPR ten times for thirty seconds on one of four sides of 30 crown replicas fixed with glass-ionomer cement (CGIZ: n = 15) or adhesive bonding (CAB: n = 15). The replicas were separated in a template during PMPR, and afterward, cleaned for five seconds per side with a sonic brush under flowing water. The artificial aging process between two PMPRs simulated a 5-year SPT with two PMPRs per year. Profilometric measurements were performed at baseline and after each second PMPR to obtain the mean change of ∆V. The statistical evaluation of the data was carried out using nonparametric tests with Bonferroni correction applied for multiple tests. Results Ninety-six out of 120 sides could be included in the analysis. PMPR methods showed a loss of substance in the luting gap with a ∆V (mean(standard deviation)) of -4.35 × 106(4.8 × 106)µm3 versus 8.79 × 104(1.05 × 106)µm3 for control at V5 (p ≤ 0.001). No significant differences of ∆V1-5 values could be identified in the control (p > 0.05), whereat all PMPRs showed a significant increasing loss of substance per simulated year (p ≤ 0.001). Intergroup comparison identified LAPA-1 as having the highest significant loss of substance determined on CAB (∆V: -1.05 × 107 (7,2 × 106) µm3), followed by LAPA-2 on CAB (∆V: -6.29 × 106 (4,24 × 106) µm3), LAPA-1 on CGIZ (∆V: -4.15 × 106 (3,25 × 106) µm3), LAPA-2 on CGIZ (∆V: -3.0 × 106 (2,23 × 106) µm3), RCP on CAB (∆V: -1.86 × 106 (2,23 × 106) µm3) and CGIZ (∆V: -1.2 × 106 (1,31 × 106) µm3; p ≤ 0.001)). Conclusions Within study limitations, all PMPRs caused a significantly higher loss of substance in the luting gap versus control without professional intervention, with the highest values in the CAB group for LAPA-1, LAPA-2 and RCP. Similar findings were observed for CGIZ, although the loss values were lower.

What many Westerners call criminal terrorism is, in the eyes of many Islamists, legitimate jihad. They say they are opposed to terrorism but by this they mean certain uses of force against one target but not again another. Are we talking about different phenomena when we talk about terrorism and jihad or are these basically the same? Jihad is sometimes translated as holy war, i.e. religiously sanctioned warfare. In Islam, jihad has been around for more than 1300 years. Terrorism as we know it is, as a doctrine, little more than 200 years old when we take the Terreur phase of the French revolution (1793-1974) as point of departure, or little more than 140 years old when we look at non-state propaganda-by-the-deed type terrorism of the anarchist sort. In the meantime, both terrorism and jihad have evolved, at least to some extent.

Which dispute is so resilient that it continues nearly 1,400 years after the original quarrel? It is the Sunni-Shiite dispute over the question who should succeed the Prophet Mohammed. The original struggle turns around the question if religio-political leadership should be passed on by bloodline (the Shiite imamate) or election (the Sunni caliphate). Today, this has become among some factions a fight over the monopoly to sacrifice and martyrdom, and it takes the form of a competition for political predominance in the Middle East between Saudi Arabia and Iran.

The Muslim Brotherhood in Egypt struggles to find a strategy of survival. After the military coup in early July 2013, during which hundreds of its members and supporters were killed by the army, many observers of the post-coup situation assume that the MB as a whole will go underground. Yet, this is unlikely. Even if– as has happened in recent weeks–many Muslim Brothers (MB) are arrested, numerous activists are extrajudicially killed in jails, and the organization is earmarked to be dissolved and its unlicensed clerics forbidden to preach - it will not break its backbone.[1] The Brotherhood will manage to reorganize as a mosaique of social, political and religious networks. This is due to its strategic flexibility and its ability to appeal to the most diverse sectors of society through its combination of social, political and practical actions. The historic record shows how the MB survived earlier waves of repression and indicates that the latest wave of repression will not be its end.

A decade after the bad seeds of sectarian conflict and instability have been firmly planted in Iraq, it takes little imagination to see them growing even worse in Syria. The mayhem in Syria defies every description: mass-murders and individual atrocities are committed every day and the domestic conflict is spilling over to most of its neighbors. Let us try to sketch a few scenarios; the worst, the best and the two most likely that may come out of the Syrian conflict.

What form should a counter-narrative to al-Qaeda’s single narrative take? Its claim “Islam is under attack” successfully integrates multiple Muslim grievances into one meta-narrative. It has found credibility beyond an extremist fringe of Muslim societies and has been far more successful and attractive than any counter narrative that has been devised so far by Western counter-terrorist strategists. The question if al-Qaeda’s meta-narrative merely creates an external scapegoat for problems that are to a great extent internal to Arab and Muslim societies should be the subject of an intensive, if not heated discussion within the counter-narrative debate.