PATIENT VISIT 3 – Selection of Artificial Teeth

 

1. Objective

To select artificial teeth whose form and shape will harmonize with the patient's features.

2. Instruments and Materials

a. Tooth selection kit (available in clinic)
b. Tooth requisition form (available in clinic)
c. Hand mirror

3. Procedure

a. Select and confirm the appropriate shade.  The patient's preference, age, hair, eyes, complexion, sex and racial origin influence the shade selected.  Use the Dentsply Bioblend Anterior Shade Guide (gray), Dentsply Trublend Shade Guide (purple) or Dentsply Portrait shade guide (black).  These can be found in the clinic.  The shades and molds of these three tooth systems do not fully interchange.  Make sure that if you use one type of shade guide that you use the same type of mold guide to select artificial teeth.  If the patient has an existing complete denture ask him/her to tell you what they like or dislike regarding the esthetics.  Specifically, you need to know if the shade of the existing denture teeth is a problem or not.  If the patient says the shade is no real problem or that they have never noticed it, then select the shade closest to that of the denture.  Many patients will ask for a very light shade.  That is O.K. too as long as you show them a few shades that would be more natural for them so that the patient can make an informed choice.  Once you have selected two to three potential shades, wet the shade guide and hold it against the patient's face or just under the upper lip.  Never force a patient to accept a shade that they do not want.  You will have an increased chance of an unhappy patient who will never be satisfied with the denture. 

b. The patient should have a mirror to observe the harmony or disharmony of each of the potential shades selected.  By limiting the choice of shades to two or three, you can let the patient participate with you in the shade selection.

c. Determine the general outline of the face.  Face forms may be grouped into four basic classifications - square, square tapering, tapering, and ovoid.  The Trubyte Tooth Indicator, a flat transparent plastic device may be used for this purpose.  This also may be determined by visual judgment.
POINT A - across the forehead two-thirds up from the eyebrow line.
POINT B - at the tragus of the ear or middle of the face
POINT C - at the angle of the jaw
If the lines through points A, B, and C on each side of the face are parallel, the basic form is square.

If the lines through A, B, and C cover at the angle of the jaw, the basic form is tapering.

If lines through A, B, and C form an arc with the greatest width through point B, the basic form is ovoid.

d. Observe the relative straightness of curvature of the profile at this time.  The relationship of three points -- the forehead, the base of the nose, and the point of the chin -- determine the profile.  The profile is classified as either curved or straight.  This shape can be evaluated using the Indicator or by observation.
At this point you have selected the proper shade and you should have limited the shape or mold selection to one of the typal forms based on the shape of the face and the profile. 

e. Measure the distance between the previously marked canine lines on the maxillary wax occlusion rim using the flexible ruler .  This will indicate the width of the maxillary six anterior teeth on the curve.

Measure the distance between the previously marked canine lines

f. Using the Trubyte Bioblend Mold and Dimension Guide Pamphlet  located in your Dentsply portfolio,  locate the proper size and shape tooth for your patient. Compare your inter-canine width measurement with the measurements in numbers in the pamphlet.  These should roughly correspond to the figures you have obtained by making measurements on the maxillary occlusion rim.  In this manner you will obtain a mold suitable in contour and size to the patient's face.  Select two or three that are suitable and let the patient choose the mold he or she prefers.

g. To select the mandibular anterior teeth, use the mold indicated on the tooth selection chart in the Mold and Dimension Guide Pamphlet.  For example, if you selected mold number 12 G, the proper mold for the mandibular anterior teeth for a patient with a Class I ridge relationship and jaw sizes that are in harmony would be lower mold "R".  If the patient has a Class II ridge relationship and the jaw sizes are not in harmony, then the width of the six mandibular anterior teeth on the curve in a Class II situation should be less than the overall width if the anterior mold for a Class I patient.  Therefore, a smaller mandibular mold must be selected.  Conversely, if your patient has a Class III relationship, you must select a mandibular mold that would be greater in overall width than the mold indicated on the selection chart. 
At this point you should have selected the maxillary and mandibular anterior denture teeth for your patient.  You should have a proper anterior mold and shade.  You are now ready to select posterior teeth.

Posterior Teeth

Posterior teeth are selected for their occlusogingival length, cuspal inclination, material, and shade.

1. Posterior artificial teeth are manufactured with cuspal inclines that vary from relatively steep to flat.  The most commonly used posterior teeth are those with cuspal inclinations of 33 degrees, 30 degree 20 degree, reduced cusp, or 0 degree.
33 degree posterior teeth offer the maximum opportunity for a fully balanced occlusion.  20 degree posterior teeth are semi-anatomic in form and wider buccolingually than 33 degree teeth.  Non anatomic tooth forms provide little or no cuspal inclination.  They may be indicated when Class II or Class III jaw relationships are present.  You should treat one edentulous patient with cuspless posterior teeth and one edentulous patient with 30 degree or 33 degree posterior teeth.  You may treat your remaining patients with either monoplane or anatomic posterior teeth.  You may decide to use lingualized occlusion selecting a cusp tooth for the maxillary arch and non anatomic teeth for the mandibular arch. 

2. Mark a point on the crest of the mandibular ridge where the ridge inclines superiorly.  This point is the maximum extent posteriorly that artificial teeth may be placed.  When there is a sharp upward incline from the residual ridge to the retromolar pad, the denture will be unstable if teeth are placed posterior to the upward incline of the ridge.  The most posterior placement of the artificial teeth is at the point where the incline begins.  Use a ruler to measure the distance from this mark to the location of the distal of the canine tooth.  This measurement in millimeters will give you the approximate size of the appropriate posterior mold.  For example, if your measurement is 32 mm, then the correct selection would be a mold that reads 32.  Posterior teeth sizes generally are available in sizes like 29, 31, 33 (small, medium, large).

3. Observe the space available in the posterior region on the mounted master casts.  The occlusogingival  dimension of the posterior teeth should correspond to the interarch distance available between the mounted casts.  If, for example, you had previously measured 32 mm of mesiodistal space available and you have observed that there was considerable interarch space available between the maxillary and mandibular ridges, you would select a mold that said 32 L.  The letter "L" indicates a long occlusogingival length.  If you had less interarch space available, then you would select a tooth that said 32 M.  The letter "M" indicates a medium amount of occlusogingival length.

4. Material: Select either porcelain, acrylic resin or I.P.N. posterior teeth.  There are indication and contraindications for the use of each.  The final choice of material for a given patient is your decision.  Acrylic teeth (and I.P.N.) are easier to adjust than porcelain teeth.  This can be an advantage when much adjustment to the denture is necessary to arrange them.  Porcelain teeth are more abrasion resistant than acrylic teeth.  They are not affected by flaming the wax.  The patient is much more likely to suffer a loss of vertical dimension due to occlusal wear with porcelain teeth.  Porcelain teeth can fracture if the denture is dropped and click when the patient occludes.  They are difficult to arrange if the patient has large residual ridges when much grinding is involved.  Porcelain teeth don't bond to the acrylic resin denture base.  They are held in mechanically by pins and holes.  This makes it difficult to retain the teeth in the denture base.  Consult your clinical faculty member for more information.

5. Use the anterior shade you have previously selected to obtain the proper shade for the posterior teeth. 

The final selection of both anterior and posterior molds and shades should be entered in the patient's progress notes.  This will facilitate any repairs or fabrication of future dentures for the patient.

Note: Please note that the arrangement of the maxillary anterior teeth depends upon the proper labial contour of the maxillary occlusion rim occluso-gingivally, and the proper midline and canine marks on this rim.  This information is necessary to arrange the anterior teeth tentatively without the patient present.  When the patient returns for the next appointment, you are then able to confirm this anterior arrangement with your patient and make any needed changes at this time.

This ends the clinical procedures for Visit 3. (Finally)