Smooth tooth surfaces & restorative material blocks show similar in situ plaque composition, according to a recent study published in the Journal of Dentistry.
The aim of this study was to investigate 12 h in situ bacterial colonization on different restorative materials with smooth surfaces.
The restorative materials examined included resin composite (RC), a glass ionomer cement (GIC), casein phosphopeptide-amorphous calcium phosphate modified GIC (CPP-ACP GIC, 3% w/w), and control bovine teeth. Polished bovine tooth and material slabs (average roughness < 0.2 μm) were prepared. Specimens were mounted in a custom-made removable appliance, then placed for 12 h in the oral cavities of ten systemically and orally healthy volunteers (23-30-year-old). The colonized bacteria on the restorative materials were evaluated by real-time quantitative polymerase chain reaction (q-PCR) and 16S rRNA gene sequencing.

Results:
The in situ bacterial colonization, in terms of both total bacterial biomass and bacterial community composition, was similar among the restorative materials tested. The microbiota of early plaque comprised similar "core microbiota", which were dominated by species within the genera of Streptococcus, Haemophilus, Neisseria, Gemella, and Prevotella, regardless of the type of underlying surface. Beta-diversity analyses revealed that most differences in the microbiota profile among samples were attributed to inter-individual variation, rather than the different materials. The microbial community composition of 12 h in situ plaque appeared different from that of the whole saliva.
Thus, the similar bacterial composition of 12-h in situ plaque was observed on smooth material and tooth surfaces tested, including species mainly from within the Streptococcus, Haemophilus, Neisseria, Gemella, or Prevotella genera. The high inter-individual variation in plaque microbiota observed in this study, which outweighed the potential differences among various materials, demonstrated the importance of an in situ biofilm model as well as consideration of the host oral an microbial backgrounds when evaluating the bacterial colonization on restorative materials.
Reference:
Evaluation of 12-hour in situ bacterial colonization on smooth restorative material surfaces by Hongying Hu et al. published in the Journal of Dentistry.
https://www.sciencedirect.com/science/article/abs/pii/S0300571222001282