Early and mature biofilm on four different dental implant materials: An in vivo human study.

OBJECTIVES: The aim of this study was to examine the microbial composition of early (after 3 days, D3) and mature biofilms (after 31 days, D31) on materials typically used in implant/abutment buildups. Implant/abutment materials with different surface roughness values (Ra ) were compared to detect differences in the quantity and quality of bacterial composition. MATERIAL AND METHODS: Four different materials were investigated: rough implant surface (sand-blasted acid-etched titanium, Ti-p), implant collar (machined titanium, Ti-m), titanium abutment (Ti6Al4V), and zirconium dioxide abutment (ZrO2 ). Fourteen periodontally healthy subjects received mandibular acrylic devices with four disks (one for each material) facing the anterior lingual area. The total bacterial count was analyzed using RT-qPCR. Both presence and proliferation of 20 selected bacterial species were assessed with microarrays. RESULTS: The highest mean total cell counts (x108  ± standard deviation) were detected at D3 on ZrO2 (5.63 ± 4.83; Ra  = 0.74 µm), followed by Ti-p (4.53 ± 5.00; Ra  = 1.87), Ti-m (4.43 ± 9.38; Ra  = 0.18 µm), and Ti6Al4V (3.83 ± 3.13; Ra  = 0.16 µm). ZrO2 showed significantly higher total bacterial cell counts than Ti-p and Ti-m (p < .05) for both time intervals. The microarrays detected 16 (D3) and 17 (D31) bacterial species; those associated with healthy oral microbiotas, but also bacteria of the red complex (Tannerella forsythia, Treponema denticola), were found on all materials. CONCLUSIONS: Biofilms on ZrO2 harbored a higher total number of bacterial cells compared with those formed on titanium surfaces with much lower roughness values. Putative periodontopathogens were detected on all materials after both time intervals. Implant/abutment materials with a low surface roughness showed less biofilm accumulation.

Does professional experience save teeth? A survey among prosthodontists.

OBJECTIVES: The aim of this study is to investigate the effect of clinical experience and educational background on clinical decision-making of dentists presented with two prosthodontic cases. METHODS: A questionnaire-based survey was performed among 66 prosthodontists who were divided into two groups. The first group included clinicians from Belgium, Germany, and the Netherlands covering a wide spectrum of dental experience. The second (specialized) group consisted of German dentists performing their last module of a 3-year postgraduate master program in prosthodontics. Two patient scenarios of different complexities were presented to the participants who were asked to make an educated choice among seven therapeutic options. RESULTS: Sixty-six dentists participated. For case #1, 22 therapeutic suggestions were offered within the international group (variation 54%), while 17 options were chosen in the specialized group (variation 68%). For case #2, five (variation 12%) and four (variation 16%) different therapeutic options were planned in the groups, respectively. Treatment planning in combination with implants was clearly preferred by dentists with an experience of 20 years or less. Conversely, participants with more experience favored more conventional treatments. All differences were statistically significant (p < 0.05). CONCLUSION: Clinicians' experience and educational background had a clinically relevant influence on decision-making and treatment planning. A clear preference for implant-free therapies was noted for dentists with more than two decades of professional experience. CLINICAL SIGNIFICANCE: In complex cases, clinicians with more than 20 years of professional experience tend to save questionable teeth rather than to resort to implants. This interindividual variation might less likely occur when more external evidence is taken into account during the decision-making process.

In situ demineralisation of human enamel studied by synchrotron-based X-ray microtomography--a descriptive pilot-study.

An in situ study was designed to investigate naturally developed demineralisation in human enamel in a widely non-destructive manner in combination with X-ray microtomography. Samples of human enamel were carried in the oral cavity of participants for 24 h daily for either 21 or 29 days using so-called intraoral mandibular appliances (ICTs). Demineralisation was thereby generated in a natural way without causing caries in the subjects' dentition. By employing synchrotron-based X-ray microtomography (XMT) in combination with volume image analysis, a quantification and three-dimensional visualisation of different stages of mineral density loss was possible. Basic features of the demineralised samples were similar to those reported in earlier in vitro studies. However, the analysed samples showed significant differences in the morphology of surface attack and the degree of mineral density loss depending on the carrier, the exposure time and the position within the ICT. In particular, the varying local conditions within a carrier's oral cavity seem to be different than in an in vitro study. Our results show that the combination of ICTs and quantitative image analysis applied to XMT data provides an analytical tool which is highly suited for the fundamental investigation of naturally developed demineralisation processes.