Table 4.

The characteristics of in vitro studies included

Author	Year	Model Used	Carious strains	Probiotic Strains	Outcomes assessed	Methods used	Results
Schwendicke et al.[18]	2017	Biofilm	SM ATCC 25175 SM ATCC 20532	Streptococcus (TH-4)	Zone of inhibition of SM Biofilm formation inhibition Enamel mineral loss Biofilm bacterial numbers	Agar diffusion method Transverse microradiography Quantified on BHI agar	Strong inhibitory effect on S. mutans growth Reduced SM numbers in biofilms than in monospecies Mineral loss by SM×LA-5 biofilms was higher than monospecies Bacterial numbers least in monospecies biofilm and highest in mixed species
Walker et al.[15]	2016	Not mentioned	SM ATCC 25175	S. salivarius JH	S. mutans inhibitory activity	Testing dextranase and BLIS activity	Increased anti-S. mutans activity
Lee and Kim[19]	2014	Biofilm	S. gordonii ATCC 10558 S. oralis ATCC 9811 S. sanguinis 804 S. mutans ATCC 25175	S. thermophilus	Antimicrobial activity Bacterial count Quantify changes in GTFS expression	Kirby-Bauer disk diffusion Petroff-Hausser counting chamber RT-PCR	Lactobacillus strains formed wider bacteria free zones than S. thermophilus

BHI: Brain-heart infusion, S. salivarius: Streptococcus salivarius, S. mutans: Streptococcus mutans, S. thermophiles: Streptococcus thermophiles, S. gordonii: Streptococcus gordonii, RT-PCR: Real-time polymerase chain reaction