How the Perfect 90 Works

Incorporating a level on the bite fork, The Perfect 90 precision verification instrument is designed to prevent errors and potential changes when impressions, models, and bite registrations are transferred from the dentist to the laboratory.  Designed by a Certified Dental Technician it permits verification of straight horizontal and vertical midlines to an accurate 90 degree angle; it also aids in the build-up of porcelain on anterior esthetic cases.  It helps the dentist set an accurate bite stick registration and helps the technician mount and articulate models with the bite stick registration.

Following are the step-by-step chairside procedures for using The Perfect 90.

1.  Place the patient in an upright position.

2.  Syringe fast-set bite registration paste on the occlusal of premolars and on the incisal
     of anteriors (Fig 2.).

3.  Have the patient bite down into bite registration and hold.

4.  Add more paste to the facial surfaces where the maxillary anterior teeth meet the
     mandibular anterior teeth.

5.  Place the "bite stick" horizontally into the bite registration paste, facial to the anterior
     teeth (Fig 3.). Have the patient look straight ahead and verify that the stick is parallel
     to the patient’s interpupillary line.

6.  Place the prongs of The Perfect 90 on top of the stick on either side of the mouth (Fig. 4).

7.  Check to see if the bubble in the level is centered.  If not, adjust by pressign downward
     lightly on either the right or left prong until the bubble is centered in the cylinder (Fig. 5).
     This indicates that the stick is at a 0 degree horizontal.

8.  Now verify that the vertical portion of The Perfect 90 is in line with the patient’s vertical
     mid-line. Note:  In cases where shifting of the midline to the right or left will occur,
     or where the patient’s occlusal plane is not obviously horizontal (but at an angle), do not
     align the vertical piece with the midline (Fig. 6); the technician can obtain the new mid-
     line with The Perfect 90 in the laboratory.

9.  As the bite registration paste sets, periodically re-verify that the stick remain horizontal
     and parallel to the interpupillary line by making sure the bubble is centered in the level
     when the prongs are placed above the stick.  Note: This re-verification is necessary
     because lip or cheek movement could inadvertently bump the stick out of position.

Figure 7 shows the highly esthetic final results of using The Perfect 90.