Influence of Root Post Materials and Aging on Fracture Strength and Marginal Gap Quality of Ceramic Crowns-An In Vitro Study

The design of and materials for prosthodontic abutments and posts have significant influences on the fracture resistance of restored teeth. This in vitro study compared the fracture strength and marginal quality of full-ceramic crowns as a function of the inserted root posts via simulation of a five-year period of use. Test specimens were prepared from 60 extracted maxillary incisors using titanium L9 (A), glass-fiber L9 (B), and glass-fiber L6 (C) root posts. The circular marginal gap behavior, linear loading capacity, and material fatigue after artificial aging were investigated. The marginal gap behavior and material fatigue were analyzed using electron microscopy. The linear loading capacity of the specimens was investigated using the Zwick Z005 universal testing machine. None of the tested root post materials showed statistically significant differences in marginal width values (p = 0.921), except in the case of marginal gap location. For Group A, there was a statistically significant difference from the labial to the distal (p = 0.012), mesial (p = 0.000), and palatinal (p = 0.005). Similarly, Group B showed a statistically significant difference from the labial to the distal (p = 0.003), mesial (p = 0.000), and palatinal (p = 0.003). Group C showed a statistically significant difference from the labial to the distal (p = 0.001) and mesial (p = 0.009). Linear load capacity reached mean values of 455.8-537.7 N, and micro-cracks occurred after artificial aging, predominantly in Groups B and C. Through the chosen experimental design, it was shown that the root post material and root post length had no influence on the fracture strength of the test teeth before or after artificial aging. However, the marginal gap location depends on the root post material and its length, which is wider mesially and distally and also tends to be greater palatinally than labially.

Predictors of perceived pandemic preparedness among general practitioners

Background

General practitioners (GPs) are essential for providing and maintaining health care during a pandemic. Pandemic preparedness (PP) of GPs can play a vital role in their management of a pandemic situation. This study aimed to examine the association stockpiled personal protective equipment (PPE) and knowledge of pandemic plans on perceived PP among German GPs. This analysis is part of the research project COVID-GAMS (Funding code: 01KI2099).

Methods

Three multivariable linear regression models were developed based on an online cross-sectional survey for the period March-April 2020 (the onset of the pandemic in Germany). Data were collected using self-developed items on self-assessed PP and knowledge of a pandemic plan and its utility. The stock of seven PPE items was queried. For PPE items, three different PPE scores were compared. Control variables for all models were gender and age.

Results

508 GPs were included in the study; 65.16% believed that they were very poorly or poorly prepared. Furthermore, 13.83% of GPs were aware of a pandemic plan; 40% rated those plans as beneficial. The stock of FFP-2/3 masks, protective suits, face shields, safety glasses, and medical face masks were mostly considered completely insufficient or insufficient, whereas disposable gloves and disinfectants were considered sufficient or completely sufficient. The stock of PPE was significantly positively associated with PP and had the largest effect on PP across all models; the association of the knowledge of a pandemic plan was significant but considerably smaller. PPE scores did not vary considerably in their explanatory power. The assessment of a pandemic plan as beneficial did not significantly affect PP.

Conclusions

An adequate stockpile of PPE is essential for perceived pandemic preparedness among GPs. Pandemic plans are considered less important for GPs. General practitioners, health authorities, and policy makers should focus on stockpiling PPE for future pandemic emergencies.

Key messages

Sufficient stockpiled personal protective equipment is the most important factor influencing pandemic preparedness of general practitioners in Germany. Knowledge on a pandemic plan has a subordinate effect on pandemic preparedness of general practitioners; usefulness of a pandemic plan does not have a significant effect.