Prosthodontics (lecture 14)
**The lecture slides are contained in “Selective grinding and Milling” slides, starting from slide 100. I’ll write the extra notes that the doctor mentioned about each slide. You need to study the slides with the sheet
Today we’ll talk about Occlusal Analysis which is the last step after inserting the dentures properly.
“Patient bites forcefully for one minute simulating compression of tissues after the patient has worn the denture for a period of time”
Because sometimes the dentures are not adapted properly to the tissues; they need a period of time to compress the tissues stimulating function.
We use then articulating paper between upper and lower teeth and ask the patient to open and close his mouth in centric occlusion then check the contacts.
If premature contact between posterior teeth causing open anterior bite between the anterior teeth (it’s preferred to eliminate these interferences before the remount) but if found at the time of the try in session we take the occlusal relationship while the dentures are in the patient’s mouth, then mount the dentures on the articulator and do the required grinding. (this step can be done in the clinic it’s not a long procedure unless the interferences are severe and need major adjustments)
Shifting of the denture bases; using the articulating paper inside the patient’s mouth might not be that accurate.
Tissue distortion; the denture may cause pressure on some areas and the patient will avoid it so the occlusal relation won’t be accurate.
Eccentric closures by the patient; very difficult to judge intra-orally.
Bite registration material should be hard and used in small amounts.
When recording the centric relation ask the patient to close his teeth together until the first touch between the teeth. If there’s a premature contact it will be first registered then the patient will shift till the maximum interdigitation, and this is wrong because here we’re not seeking for the final position of the teeth in occlusion we want to find any premature contact/s.
**You’ve to make sure that this registration is repeatable, repeat it without the bite registration material it should be the same.
So if you want to identify the premature contact ask the patient not to close his teeth forcefully; just bite slowly and gradually until the first touch between the teeth is achieved.
For bite registration material you can use Silicone which is the most accurate and the most expensive (pic slide 105). Or you can use wax –trade name Aluwax- (slide 106)
The upper denture is mounted already due to the indexes or jigs that we previously made.
The lower denture is placed to the upper denture according to the bite registration.
Remember in excursive movement there should be working and balancing contacts; where the balancing shouldn’t be heavier than the working. There should be smooth excursions between the teeth.
After doing the occlusal analysis we check the Phonetics.
Keep in mind that certain letters are pronounced by certain movements of the lips and teeth.
‘F’ sounds: maxillary incisors touch lowerlip; So if the upper incisors are not placed correctly the F will be pronounced incorrectly.
‘S’ sounds: incisors closetogether posterior teeth do not contact; so if the S is pronounced incorrectly you’ve to know that there’s wrong positioning of the teeth or in the FWS.
Any area you’ve adjusted –except for the fitting surface- you should polish it.
You can use multiple instruments in polishing they differ in shape according to the area you want to polish.
Finally you provide your patient with the knowledge that he must know.
-About cleaning for example, toothpaste shouldn’t be used with the acrylic teeth since it cause abrasion, soap and water are used instead. Ask your patient to wash his denture in hydrochloride solution every 1 week for about 10 minutes to get rid of any microbial or fungal infection.
-Denture shouldn’t be worn during sleeping –at night- , you must give the tissues time to relief the pressure.
-You’ve to notify your patient that mastication and speech will be difficult during the first few days but adaptation will be obtained gradually.
-It’s very normal to have any irritation at the first few days. (Redness, ulcers, discomfort at certain areas) the patient can still use the denture but if it’s severe you have to adjust them (we’ll talk about them later on)
-Chewing shouldn’t be done on the anterior teeth until the patient adapts good mastication on the posterior.
-Ask the patient to have small bites of soft food on both sides of the denture posteriorly, to have balanced contacts.
-Excessive salivation is normal.
The doctor read the summary slides 123 and 124.
One week is the most suitable time for the patient to adapt to the denture and discover any problems.
NEVER try to adjust unless you’re very sure from where the problem is.
These problems are the most common and their treatment is known as well.
One of the most common; the patient feels that his teeth are high and the pain is getting worse. In denture base problems you don’t apply the pressure indicating paste (PIP) all through the base –as in the picture slide 132- this is wrong you apply it only on the area that the patient is complaining about. Or you can apply the PIP on the reddened or ulcer tissue then place the denture (more accurate).
Retention problems are linked to over/underextension, you apply PIP on the borders if it remains with streaks this mean that there’s no contact between the flange and the sulcus so the borders are short.
If the OVD is insufficient the patient will feel no power in chewing whish means that he should move his teeth in a long space to chew food, in this case you have to reset the teeth.