Microbial community succession on developing lesions on human enamel

Dental caries is one of the most common diseases in the world. However, our understanding of how the microbial community composition changes in vivo as caries develops is lacking.An in vivo model was used in a longitudinal cohort study to investigate shifts in the microbial community composition associated with the development of enamel caries.White spot lesions were generated in vivo on human teeth predetermined to be extracted for orthodontic reasons. The bacterial microbiota on sound enamel and on developing carious lesions were identified using the Human Oral Microbe Identification Microarray (HOMIM), which permits the detection of about 300 of the approximate 600 predominant bacterial species in the oral cavity.After only seven weeks, 75% of targeted teeth developed white spot lesions (8 individuals, 16 teeth). The microbial community composition of the plaque over white spot lesions differed significantly as compared to sound enamel. Twenty-five bacterial taxa, including Streptococcus mutans, Atopobium parvulum, Dialister invisus, and species of Prevotella and Scardovia, were significantly associated with initial enamel lesions. In contrast, 14 bacterial taxa, including species of Fusobacterium, Campylobacter, Kingella, and Capnocytophaga, were significantly associated with sound enamel.The bacterial community composition associated with the progression of enamel lesions is specific and much more complex than previously believed. This investigation represents one of the first longitudinally-derived studies for caries progression and supports microbial data from previous cross-sectional studies on the development of the disease. Thus, the in vivo experiments of generating lesions on teeth destined for extraction in conjunction with HOMIM analyses represent a valid model to study succession of supragingival microbial communities associated with caries development and to study efficacy of prophylactic and restorative treatments

Comparison of antibacterial properties of commercial bone cements and fillers with a zinc based glass polyalkenoate cement

Postoperative infection following invasive surgical procedures is a significant cause for concern, particularly in spinal reconstructive surgery. The objective of the study was to compare the antibacterial efficacy of a novel zinc based glass polyalkenoate cement (Zn-GPC) based on 0.04SrO-0.12CaO-0.36ZnO-0.48SiO2 glass, to a number of commercially available bone cements and fillers including Simplex P + Tobramycin (STob), Spineplex (Spine) and Novabone Putty (NPut). The agar diffusion test was performed on each material against E. coli, S. epidermidis, P. aeruginosa and S. Aureus. STob was found to produce large inhibition zones in each of the bacteria tested and was statistically significantly higher than any other material. The experimental Zn-GPC (BTSC) was found to exhibit antibacterial properties in both E. coli and S. epidermidis. Neither Spine nor NPut showed any inhibitory effect in any of the bacteria tested. A study was also performed to determine the effect of antibiotic release from STob and the Zn-GPC (BTob) containing the antibiotic tobramycin (Tob). Antibacterial efficacy was found to increase with respect to maturation with BTob, whereas STob was found to decrease significantly over the time period 0 – 14 days. The final objective was to investigate any change in agar composition during the agar-diffusion test. Little change was observed for STob as antibiotic release cannot be determined using EDX. There was however an increase in Zn levels when analysing BTSC which suggests that Zn is playing a role in the antimicrobial nature of the Zn-GPC. No significant changes were observed for Spine or NPut