- A minimum of 20 natural teeth (all teeth; incisors, canines, pre-molars & molars), and a minimum of 40 gradable surfaces for MGI, BI and PI. A scorable surface is defined as a surface that has 50% of the surface gradable for each clinical index. Third molars, orthodontically banded/bonded, fully crowned or extensively restored or grossly carious teeth are not included in the tooth count, moderate gingivitis present at the screening visit (in the opinion of the clinical examiner from a gross visual examination) and mean whole mouth MGI between 1.75 and 2.30 and a mean overall PI score >1.5 at Baseline visit.