Thanks very much, professor.  I am now reading that paper.  I know it will be very useful.

I suggested using saliva sample, and express the result in form of CFU/ml of saliva.

I would definitely vote for the plaque, simply because the saliva contains DNA from all the bacteria from all the various oral sites (tongue, tonsils, cheeks, plaque (supra- and subgingival), etc. and the saliv is not representative of any one oral site. The plaque contains the suspected putative agents in a much more specific and concentrated form. Wenche S. Borgnakke

I am really thankful with all your answers.  We are going to assess whether long term consumption of yogurt containing Lactobacillus rhamnosus would affect the Colony Forming Units of Streptococcus mutans in children aged 2 to 10 years old.

Plaque seems to be more reliable method, however I suggest that you do both plaque and unstimulated saliva.

I think it depends on what you are heading for. If you took plaque sample, get ready for questioning many factors of characteristcs and plauqe flora. if you took saliva sample, then you are exploring  even more general population. I suggeat unstimulated saliva as base then palque if you may. Also, it will be interesting to see the relationship between the 2 samples/participant.

We have a study (not published yet) in which we collected both, plaque from caries active sites and stimulated saliva. More SM counts were recovered from dental plaque samples from caries active individuals when compared to saliva, but from caries free individuals no difference in SM counts was seen between plaque-saliva samples. So, if possible, collect both.

I think you should measure unstimulated saliva instead of stimulated.

It is really depends on your research questions.  If the project just want to learn the overall S. mutans level in the oral cavity, particularly for young children, the saliva sample is sufficient.

Intersting question. Strep mutans is no longer considered the bad guy any more.  The issue is more of what bacteria do you have that produce acid, and there are over 50 that do including Aa.  It seems Sm is more of an issue in young kids for example under age 6-12 mos. But after that, it is not the main issue. You can have pts with NO Sm and still be loaded with caries. Thus, pH and not sugar is the issue.

See;

1. M Fontana

2. Featherstone - California Dental Journal Oct. 2007.

3. Doug Young, works with Featherstone

If you are looking to graphically show a mom or pt how bad things are and if they don't change and you want to scare them, may I suggest the GC America Strep Mutans Saliva check.  Easy to do:

1. pt spits into plastic cup for 5 min

2. take saliva and place on a small rectangular plastic thing that looks like an early pregnancy test stick

3. wait 15 min

4. 1 red line = less than 500,000 colonies

    2 red lines = more than 500,000 colonies

seems more than 500K colonies puts you at a greater risk for caries.

But if you want to be more accurate and see what your acid production is, may i suggest the the Oral Biotech CarieScreen. It measures the actual level of ATP of the bacteria collected on the lingual of the mandib 6 anteriior teeth.  The # goes from 0 - 9999, anything over 1500 indicates greater risk for caries and it gets higher the higher the number.  It measures ATP. Cariogenic bacteria have and use lots of ATP in order to push against the pressure gradient the amount of H+ they produce and keep it out of the cell. Takes lots of ATP.

Hope this helps.

Lance

Lance Kisby DMD, FASDC, FAAPD, MAGD

Prog. Dir. Pediatric Dentistry residency

Nemours Hospital for Children

Wilmington, DE

PS: Have a great weekend