Why does my reading going in negative while doing programming for balanced denture in hanau wide veu
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Hanau Wide-Vue articulator negative condylar inclination reading balanced denture programming
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negative condylar inclination reading programming balanced denture
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This is a very practical question with a clear technical answer. Here is a full explanation:
Why You Get a Negative Reading on the Hanau Wide-Vue During Balanced Denture Programming
The Short Answer
The Hanau Wide-Vue condylar track is designed to move between -20° and +60°. A negative reading is not necessarily an error - it is actually a valid, built-in range of the articulator. However, if you are getting an unexpected negative reading during protrusive record programming, it almost always comes down to one of the causes below.
Understanding the Condylar Track Range
The condylar track on the Hanau Wide-Vue can be set from:
- Zero (0°) - neutral/flat
- +60° - steep positive inclination (steep condylar path)
- -20° - negative inclination
The negative range exists intentionally to simulate a flat or reverse condylar eminence - a real anatomical variant some patients have, particularly edentulous elderly patients where the eminence has flattened over time due to resorption or wear.
Common Reasons You Are Reading Negative
1. Protrusive record made with insufficient protrusion
This is the most common cause. If the patient did not protrude far enough (minimum 6 mm is recommended), or if the record was made in a near-centric position, the articulator condylar element will not travel far enough anteriorly-inferiorly. When you seat this inadequate record and adjust the condylar guidance, it reads at zero or negative.
- Fix: Re-take the protrusive record ensuring at least 6 mm of anterior protrusion - ask the patient to bring the lower jaw forward as far as comfortably possible before biting into the wax.
2. The protrusive record is inverted or seated incorrectly
If the protrusive record is placed upside down or reversed on the cast, the upper member will be guided in the wrong direction relative to the lower, forcing the condylar guidance to tilt negatively to accommodate.
- Fix: Check that the record is seated correctly - upper rim impression into the upper record, lower rim into the lower impression.
3. Incisal pin not elevated before programming
The Hanau Wide-Vue instructions specifically state: raise the incisal pin before loosening the condylar guidance thumbnuts when seating the protrusive record. If the incisal pin is resting on the incisal guide table, it creates interference that prevents the upper member from properly following the protrusive record. The condylar element then cannot drop downward and forward as it should, resulting in a zero or negative reading.
- Fix: Always elevate the incisal pin FIRST before seating any interocclusal record for condylar programming.
4. Centric locks not released
If the centric locks (lateral lock screws on the upper member) are not loosened before seating the protrusive record, the upper member cannot freely move into protrusion. It will appear to "seat" but the condylar elements are not actually tracking the protrusive path.
- Fix: Loosen both centric locks before programming.
5. Over-thick or distorted protrusive record
A wax record that is too thick or has been distorted after removal from the mouth will not accurately reproduce the protrusive jaw position. Thick records tend to open the vertical dimension excessively without true anterior condylar translation, producing a false low/negative reading.
- Fix: Use a thin, properly chilled protrusive record (zinc oxide eugenol paste or a lightly softened, thin wax wafer). Cool the record before removing from the mouth.
6. Face-bow transfer error
If the face-bow was not transferred accurately to the articulator (wrong axis point, wrong orbital pointer setting, etc.), the upper cast will be mounted in a position that does not reflect the true hinge axis. When the protrusive record is then used, the condylar path reading will be incorrect - often reading lower or negative.
- Fix: Verify your face-bow mounting. The Hanau Wide-Vue uses an ear-bow face-bow referenced to the external auditory meatus.
When a Negative Reading is Actually Correct
In some geriatric or long-term edentulous patients, the articular eminence genuinely flattens or even reverses. A reading between 0° and -20° may be clinically accurate for these patients. In such cases, you would proceed with programming at that negative value and adjust your occlusal scheme accordingly (flatter cusps, reduced compensating curve).
Summary Checklist Before Re-programming
| Step | Check |
|---|---|
| Protrusion amount | Minimum 6 mm forward? |
| Incisal pin | Elevated before seating record? |
| Centric locks | Both loosened? |
| Condylar thumbnuts | Both loosened? |
| Record orientation | Correct side up, correct arch? |
| Record thickness | Thin and undistorted? |
| Face-bow | Correctly transferred? |
If you go through this checklist and still get a negative reading, it is likely a true reflection of your patient's flat condylar eminence, and a setting between 0° and -20° is appropriate.
How do you determine the correct Bennett angle if the protrusive reading is negative?
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Bennett angle Hanau formula L=H/8+12 negative condylar inclination complete denture
Good - the official Whip Mix instructions confirm the formula and the alternate lateral record method. Here is the complete answer:
Determining the Bennett Angle When H is Negative
The Formula Still Works - With a Caveat
The Hanau formula is: L = H/8 + 12
When H is negative, you simply plug in the negative value:
| H (Protrusive reading) | Calculation | L (Bennett angle) |
|---|---|---|
| +40° | 40/8 + 12 | 17° |
| +20° | 20/8 + 12 | 14.5° |
| 0° | 0/8 + 12 | 12° |
| -10° | -10/8 + 12 | 10.75° ≈ 11° |
| -20° | -20/8 + 12 | 9.5° ≈ 10° |
The math is valid. A negative H produces a Bennett angle somewhere between ~10° and 12° - still a positive number, still a meaningful setting. The formula does not break down; it just gives you a lower Bennett angle, which is physiologically logical: a flat or reverse condylar eminence means there is less condylar guidance controlling lateral movement, so the Bennett angle needs to be proportionally smaller.
Why This Makes Biological Sense
The Bennett angle represents the medial wall of the glenoid fossa resisting lateral condylar movement. When the eminence is flat (H near zero or negative), the fossa geometry is generally shallow overall - including the medial wall. A lower Bennett angle is consistent with this flatter joint morphology. Setting a high Bennett angle (e.g., 20°) on a patient with a flat eminence would over-restrict lateral movements on the articulator relative to what the patient can actually do.
The Preferred Method: Use Lateral Records Instead of the Formula
The official Hanau Wide-Vue instructions note that the formula is one option, but describe an alternate - and more accurate - method: programming the Bennett angle directly from lateral interocclusal records. When H is negative or near zero, this direct method is preferable over relying on a derived formula:
Steps using lateral records:
- Loosen both centric locks, raise the incisal pin, loosen thumbnuts for condylar inclination AND Bennett angles on both condylar guidances
- Seat the right lateral record on the lower cast
- Guide the upper member into right lateral position until the upper rim seats into the record
- Slowly rotate the left condylar guidance (the balancing side) back and forth until the rims seat fully - tighten the thumbnut at that position (this sets the left Bennett angle)
- Set the left balancing condylar guidance to "brass to brass" (flat side of condylar element contacting the shoulder on the condylar shaft) to lock the Bennett angle
- Repeat with the left lateral record to set the right condylar guidance Bennett angle
This method is independent of any formula and directly captures the patient's actual lateral condylar path - far more reliable when H is unusual.
Practical Guidance for a Negative H Case
- First, confirm the negative reading is real (go through the checklist from the previous answer)
- If confirmed real, use the formula: plug in the negative value - you will get a Bennett angle in the ~10-12° range
- Better yet, take lateral records and program the Bennett angle directly - this bypasses the formula entirely
- For tooth selection and setup, a flat eminence means you should use zero-degree (cuspless) or low-cusp teeth (0°-10°), reduce the compensating curve, and rely more on the flat occlusal plane for balance rather than condylar guidance
- Do not set the Bennett angle to zero just because H is negative - even the flattest joints have some medial wall, and ~10° is physiologically appropriate as a minimum practical setting
Key Point to Remember
The Bennett angle on the Hanau Wide-Vue ranges 0° to +30°. You cannot set it to a negative value. When H is negative, the formula still gives you a positive L (because of the +12 constant), so you always have a valid, settable Bennett angle. The +12 in the formula is specifically there to account for the average immediate side shift component that exists regardless of condylar inclination.
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