The term 'quorum sensing' describes intercellular bacterial communication which regulates bacterial gene expression according to population cell density. Bacteria produce and secrete small molecules, named autoinducers, into the intercellular space. The concentration of these molecules increases as a function of population cell density. Once the concentration of the stimulatory threshold is reached, alteration in gene expression occurs. Gram-positive and Gram-negative bacteria possess different types of quorum sensing systems. Canonical LuxI/R-type/acyl homoserine lactone mediated quorum sensing system is the best studied quorum sensing circuit and is described in Gram-negative bacteria which employ it for inter-species communication mostly. Gram-positive bacteria possess a peptide-mediated quorum sensing system. Bacteria can communicate within their own species (intra-species) but also between species (inter-species), for which they employ an autoinducer-2 quorum sensing system which is called the universal language of the bacteria. Periodontal pathogenic bacteria possess AI-2 quorum sensing systems. It is known that they use it for regulation of biofilm formation, iron uptake, stress response and virulence factor expression. A better understanding of bacterial communication mechanisms will allow the targeting of quorum sensing with quorum sensing inhibitors to prevent and control disease.

As future healthcare professionals, dental medicine students are expected to exhibit healthy lifestyle behaviors. This study aims to assess the health-promoting behaviors among undergraduate dental medicine students of all six academic study years at the University of Zagreb, and determine their predictors. Students were invited to complete a two-part survey, consisting of a self-reported sociodemographic questionnaire and the Health-Promoting Lifestyle Profile II (HPLP II). Three hundred and forty-nine students completed the survey; the response rate was 60.3%. The total mean HPLP II score was 2.64 ± 0.34. Students in the second academic study year scored the lowest (2.50 ± 0.33), and students in the sixth academic study year scored the highest (2.77 ± 0.32). Health responsibility was the overall lowest scored subcategory, while interpersonal relations was scored the highest. Female students reported lower spiritual growth and stress management than male students. Higher body mass index (BMI) was related to lower health responsibility. Smoking, place of residence and the age of participants did not seem to have an impact on health-promoting behaviors. Dental students at our faculty exhibit moderate health-promoting behaviors, even in the absence of a formal health-promoting course in the existing curriculum.

The aim of this research was to investigate the association of chronic and aggressive periodontitis with the severity of coronary artery disease which was angiographically verified. Subjects were selected among the hospitalized patients at the University Hospital Centre Zagreb who had coronary angiography done because of the chest pain. Thorough clinical examination included periodontal indices and clinical and socio-demographic characteristics of participants. Subjects were divided in two test groups, acute coronary syndrome (ACS) and stable coronary artery disease (CAD), and the control group with no significant CAD. Data were analyzed using Kruskal-Wallis and Pearson’s Chi-Square test. From 106 subjects, 66 (62.3%) were hospitalized for ACS, 22 (20.7%) had stable CAD and only 18 (17.0%) had no significant CAD. Only 26 (24.5%) out of 106 patients were never smokers (p<0.05). Chronic periodontitis was the most common finding with 68.2% in ACS group and 54.5% in stable CAD group, while healthy patients without periodontitis (72.6%) were dominant in the control group (p<0.001). Stable CAD group had the highest mean probing depth (PD) 3.92±1.16, gingival recession (GR) 1.34±0.78, clinical attachment level (CAL) 4.60±1.41 and bleeding on probing (BOP) 45.98±26.19 values, whereas ACS group had mean PD value of 3.77±0.91, GR 1.11±0.66, CAL 4.32±1.08 and BOP 41.30±22.09, and no significant CAD group had mean PD value of 3.27±0.97, GR 0.69±0.37, CAL 3.62±1.04 and BOP 26.39±13.92 (p<0.05). Periodontitis was shown to be associated with angiographically verified coronary artery disease. Physical inactivity, poor oral hygiene and periodontal inflammation were observed in patients with ACS and stable CAD.

The objective of this research was to evaluate implant stability following sinus lift with two grafting materials, and to compare it with the results obtained for the implants placed in a pristine posterior maxilla. The study included 44 healthy patients with an existing indication for sinus lift procedure (test group). 46 implants were placed following sinus lift with a pure-phase beta-tricalcium phosphate, while 39 implants were placed following augmentation with 60% hydroxyapatite with 40% beta-tricalcium phosphate material. The control group consisted of 48 healthy patients who were treated with 85 implants but without bone augmentation in posterior maxilla. Astra Tech OsseoSpeed implants were placed in all subjects. Resonance frequency analysis was used in both groups for determining implant stability 4 months after insertion. A mean implant stability quotient (ISQ) was calculated on the basis of 3 measurements. No statistical difference was observed in ISQ values of implants placed with and without augmentation procedure (p=0,789). Statistically significant difference was not found when ISQ values of implants placed following particular grafting material were compared with ISQ values of corresponding implants in a pristine bone (p=0.697 and p=0.402). This study demonstrated that the implant stability is comparable among implants placed in the posterior maxilla regardless of sinus lift and grafting procedure. Implants placed in the grafted posterior maxilla can be predictably loaded as the implants placed in a non-grafted, pristine maxilla.