Purpose: Dental education institutions worldwide experienced disruptive changes amid the COVID-19 pandemic, with a rapid switch to the online learning format. Thus, this study aimed to assess the impact of the COVID-19 pandemic on dental education and evaluates the perceptions and attitudes of students towards the introduction of online learning in the School of Dental Medicine in Zagreb, Croatia. Methods: A survey was conducted on a population of undergraduate students. It was comprised of perceptions and attitudes of students on the impact of the COVID-19 pandemic on their psychoemotional status, changes introduced in the educational system, and online learning in particular. Results: Of the 352 students that completed the survey, 66.2% of students reported being psychoemotionally affected by the lockdown. The most significant impact of the switch from in-person to online learning was observed in terms of missing contact with lecturers (60.3%) and peers (90.3%) and loss of practical courses, regarding which 65% of students agreed that they could not be compensated. While only 36.1% reported that online teaching fully met their expectations, the majority of the students (61.9%) agreed that online lectures were as valuable as in-person lectures and that the theoretical courses could be carried out online in the future as well (69.9%). Conclusions: Students reported relative satisfaction with changes in the learning format and a positive attitude towards online learning; however, several challenges and obstacles were identified.

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.

Background: this study evaluates the clinical outcomes of a novel approach in treating deep intrabony defects utilizing papilla preservation techniques with a combination of hyaluronic acid (HA) and deproteinized porcine bone mineral. Methods: 23 patients with 27 intrabony defects were treated with a combination of HA and deproteinized porcine bone mineral. Clinical attachment level (CAL), pocket probing depth (PPD), gingival recession (REC) were recorded at baseline and 6 months after the surgery. Results: At 6 months, there was a significant CAL gain of 3.65 ± 1.67 mm (p < 0.001) with a PPD reduction of 4.54 ± 1.65 mm (p < 0.001), which was associated with an increase in gingival recession (0.89 ± 0.59 mm, p < 0.001). The percentage of pocket resolution based on a PPD ≤4 mm was 92.6% and the failure rate based on a PPD of 5 mm was 7.4%. Conclusions: the present findings indicate that applying a combined HA and xenograft approach in deep intrabony defects provides clinically relevant CAL gains and PPD reductions compared to baseline values and is a valid new approach in treating intrabony defects.

Objective: Halitosis, or oral malodour, is an unpleasant smell emanating from the oral cavity. It is a common complaint among patients with periodontitis, however, their relationship is not fully elucidated. This study aimed to evaluate the association between halitosis measures, clinical indicators of periodontitis and tongue coating, as well as a novel measure, periodontal inflamed surface area (PISA). Material and methods: Data of 10 patients with periodontitis and halitosis were included in this study. Halitosis was assessed by the organoleptic method and the portable sulphide monitor, measuring volatiles sulphur compounds. A comprehensive periodontal examination was conducted, and the parameters of probing depth, gingival recession, clinical attachment level, bleeding on probing, plaque and tongue coating were registered. The PISA was calculated using clinical attachment level, gingival recession and bleeding on probing. Results: A correlation between organoleptic score and tongue coating (r=0.554) and plaque (r=0.614) could be observed. No correlation between measures of halitosis and probing depth or the PISA could be detected. A significant correlation was found between organoleptic scores and volatiles sulphur compounds values (r=0.931). Conclusion: This pilot study has shown and further reiterated a complex interplay between different factors causative to halitosis in patients affected by periodontitis. The results suggest that tongue coating and oral hygiene may have an important role in halitosis in patients with periodontitis.