3-11. SCALING THE TEETH
In scaling the facial, proximal, and lingual surfaces of each segment of the dental
arches, certain instruments and positional relationships of the PDS to the patient are
more convenient than others. Some procedures can be done better with a mouth
mirror. In any case, the chair should be adjusted so that the patient's head is at a
convenient working height (generally between the PDS's elbows and shoulders). The
patient should be comfortable. All areas of the mouth should be easily accessible for
effective work to be done. Adjusting the operating lamp for good working visibility,
maintaining a neatly arranged bracket table, and keeping instruments wiped free of
debris are also conducive to efficient work performance. An excellent time to instruct
the patient in proper toothbrushing and other self-care practices is just before beginning
the prophylaxis. With the use of disclosing solution and a hand mirror, areas needing
attention can be pointed out. Scaling procedures are then carried out as discussed
below using instruments convenient to each area. With experience, the PDS will find
that certain instruments become favorites while others are seldom used.
3-12. PREVENTIVE DENTAL SPECIALIST POSITIONS USED FOR SCALING
The working positions used by the PDS for scaling and polishing are identified in
relation to the patient, usually using the concept of a 12-hour clock face. See figures
3-10 and 3-11. A right-handed PDS generally uses the 9 o'clock position to scale
posterior teeth; a left-handed PDS uses the 3 o'clock position. A right-handed PDS
uses the 8 o'clock position to scale tooth surface sides toward the PDS; a left-handed
PDS uses the 4 o'clock position. Both right-handed and left-handed PDS's use the 12
o'clock position to scale tooth surface sides away from the PDS. Appendix D provides a
chart outlining suggested PDS positions and finger rests used in scaling, from a right-
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