Clinical and laboratory remoutning
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Transcript of Clinical and laboratory remoutning
Clinical and Laboratory Remounting
in Complete Dentures
Submitted by:
Dr.Pallavi Chavan
2nd year PG
Introduction• Complete dentures are prosthetic replacements for lost
natural teeth and lost soft and bony tissues, which are fabricated in order to restore impaired or lost functions and appearance
• Fabrication of complete dentures comprises various variables whose precise execution is of crucial importance for achieving success with fabricated dentures
• The efficiency and comfort that a patient experiences using complete dentures depends to a large extent on the harmony of the occlusion
• Occlusion established during try-in stage is subject to change because of inaccuracies incorporated during construction of dentures
• Minor faults can be corrected by selective grinding with dentures in patient's mouth, if a split cast remount procedure was used immediately after the dentures were processed.
• However, a general dental practice survey revealed that less than 5% of dentists use the split cast procedure to rectify the errors of processing
• Prosthodontist’s recommend a remount procedure for identification and correction of occlusal errors in complete dentures rather than the more common practice of placing the articulating paper intra orally, followed by spot grinding
at the chair side
• However, There is no evidence to support such recommendations
What is Remounting??
Definition:
• Remount procedure : Any method used to relate restorations to an articulator
for analysis and/or to assist in development of a plan for occlusal equilibration or reshaping.
• Remount record index : A record of maxillary structures affixed to the
mandibular member of an articulator useful in facilitating subsequent transfers
Causes of Errors in Occlusion :1. Incorrect Registration of Centric Occlusion:• Reason A :
During JR, when occlusal rims are brought together cause uneven pressure due to premature contact in the 2nd
molar or incisor region
Compression of mucosa
Displaces the mucosa away from the region of premature contacts
But, on plaster models there is no compression of tissues
Thus, different relation in mouth and articulator
Thus, an error is established which is passed through try-in and processing stages
At denture insertion the dentures contact only in areas of these premature contacts
Causes of errors in occlusion
Incorrect registration of centric occlusion
• Reason B: Imperfectly fitting record bases can cause movement of rims
while recording centric The dentures will have slightly inaccurate centric occlusion
relation and will tend to move on the ridges , causing soreness
• Reason C: The models may not be placed accurately on the articulator
while mounting
Causes of errors in occlusion :
2. Irregularities in Teeth Setting :
• Difficult to set perfectly even contact in teeth arrangement leading to some heavy contacts /pressure
• Wax has certain resiliency ,permits tooth movements to occur when interferences are encountered unlike hard acrylic in denture
• Wax can contract and move ,causing irregularities in teeth arrangement
Causes of errors in occlusion :
3. Tooth movement while Flasking and Packing
• Tooth movement while de-waxing
• Excessive packing pressures results in, the artificial teeth being forced into the investing plaster
• If the acrylic resin has reached an advanced dough stage
• Normal packing pressures when the investing mix is weakcan break the mould
Causes of errors in occlusion :
3. Tooth movement while flasking and packing
• Incomplete Flask closure
• If pressure on the flask is released during the curing cycle
• Separation of the two halves of the flask by a layer of excess resin which should have been removed during trial closure of the flask(flash)
Causes of errors in occlusion :
In spite of taking all due precautions to prevent the errors just described, small occlusal inaccuracies
invariably occur.
These errors can be corrected in the laboratory if a split-cast mounting technique is used.
An average increase in height of 0.5 mm and a shift in tooth contact towards the posterior region
T. Badel et al . Complete Denture Remounting ;Acta Stomatol Croat, Vol. 35, br. 3, 2001
4. Articulator wear:
• All articulators are subjected to wear and older and more worn the articulator the greater will be the error in occlusion and articulation
• Every piece of mechanical apparatus exhibits some play in its moving part and when this becomes easily detectable, the bearing should be replaced
5. Other factors • Over heating during polishing procedures
• Inevitable dimensional changes in the denture material during and after polymerisation
• Expansion of the acrylic resin due to water absorption
Shrinkage in denture makes the cuspal position Change in turn increasing VD.
Occlusal errors can be corrected by:
Direct correction in mouth
Laboratory remounting
Clinical remounting
Direct Correction in Mouth
1.Articulating paper It will not give an accurate indication of premature
contacts because of resiliency of supporting tissues that allows the denture to shift producing markings which are frequently false
2. Central bearing plates:• The correlator:
It has a spring loaded central pin It contacts a metal plate in the
vault This,hold the maxillary denture
up and mandibular denture down
At a premature contact,thedentures do not shift because the spring holds the teeth apart
• Coble device: Has a central bearing pin
without spring
Coble device
3.Occlusal waxes: Adhesive wax is added on the mandibular denture Points of penetration are observed and relieved
• Advantage : Can locate interference in functional movements
• Disadvantage: Can give false reading due to shift of underlying soft tissues
4.Abrasive pastes:
• Should only be used to refine occlusion after selective grinding on articulator
• Disadvantages: Shifting bases cause premature contacts Cusps maintaining vertical dimension might be destroyed
When to do Remounts ??
#1Wax—up
If the wax-up occlusion is different in
mouth compared to the
articulator
#2 Processed
After processing the VDO is increased
To get back to the original VDO
#3Delivery
Inaccurate occlusion from
all previous steps not eliminated in
prior remount
Laboratory Remounting:• Purpose:1. To correct errors in processing
2. To return dentures to the correct vertical dimension
3. To restore centric and bilateral balanced occlusion
• After processing, but before the removal of the dentures from their casts, they are returned to the articulator.
• This is accomplished by using split-cast mounting techniques, which allow easy location and removal of the cast from its mounting plaster on the articulator.
Split Cast mounting technique:1.procedure for placing indexed casts on an articulator to facilitatetheir removal and replacement on the instrument;
2. the procedure of checking the ability of an articulator to receive orbe adjusted to a maxillomandibular relation record.
• Split-cast mounting is carried out in the laboratory, by notching the base of the cast and applying separating medium just before articulating the casts.
• The cast is easily separated from the mounting plaster and is flasked after the try-in.
• The cast can be removed from the flask and reattached to the mounting plaster using cyanoacrylate glue.
Split Mounting Plates
Plexi glass with embedded split mounting plate part
Split mounting plate has 3 metal plates and a pin
Opposing section of split plate attached to the embedded section
Split Mounting Plates :
Pin removed ; plexiglass detached and other section of split plate attached to cast
Impression is boxed and poured and plexiglass is positioned on it
Masking tape wrapped around cast on the articulator
The boxing is filled with plaster
Tapered pin is removed and cast seperated
Procedure for Laboratory RemountingAfter Remounting ,check the incisal pin
and incisal table contact (1-3mm)
Check contacts between heals of the casts and dentures
Place articulating paper ,and gently tap
After the centric check eccentric and protrusive contacts
Adjust these contacts by selective teeth grinding
Clinical Remounting• It consists of remounting the finished denture on an
articulator by using new inter-occlusal records in the patients mouth
• The purpose of clinical remounting is to accommodate the errors made during centric relation records
Advantages :1. It reduces patients participation
2. It permits the dentist to see better what he /she is doing
3. It provides stable base ,eliminating the resilient tissues
4. Absence of saliva makes markings more accurate
Steps for Clinical RemountingI. Registration of centric relationship without tooth contact
II. Lateral or protrusive records
III. Facebow registration
IV. Mounting the dentures
V. Correcting the occlusion by spot grinding
I. Registration of Centric Relationship without Tooth Contact
• Easily and quickly heat softened
• Records can be modified changed, corrected and verified with comparative ease
• Can distort • Care while handling
Aluwax
• Records of impression plasters are accurate, rigid after setting difficult to handle
• brittlePOP
• Accurate• Stable • Do not need a carrier• Not enough working
time• Resistance to
compression on setting
Silicones
Remounting at Increased Vertical Dimension or Correct Vertical Dimension??
• When the vertical discrepancy is 2 mm or less, we are often tempted to record the new interocclusal record at the same vertical
• But,when even one tooth makes contact on one side ,it can shift the bases and cause inaccurate records.
Steps for clinical remounting
• Therefore,
• The remounting records are made at higher vertical dimensions
• i.e :if 2 mm of error + 1-2 mm of material space = 3-4 mm of increased vertical dimension
• This increase should be nullified back,to the original vertical dimension by grinding
Steps for clinical remounting
• Occlusal errors at wax try-in stage can be corrected by removing the interfering tooth/teeth
• New interocclusal record is then made at the same vertical dimension
• This is a more accurate and physiologically appropriate method
Steps for clinical remounting
Procedure for Interocclusal Record without Tooth Contact• Two aluwax doubled layered strips (1/2”) are immersed in
water bath of 540c for 30 sec.
• Maxillary denture is seated in mouth, followed by mandibular and stabilized with the index finger over buccalflange area.
• Then the Mandible is guided into CR closing lightly into the wax.
Steps for clinical remounting
• As contact with the wax approaches the fingers are removed and the patient is instructed to close into the wax until a good index is made
• The imprints of opposing teeth must be crisp and 1mm deep with no penetration of wax record by opposing teeth
If the teeth make contact ,the lower cusp will guide the mandible to the previous wrong position of occlusion ,thus preventing the
desired correction
Steps for clinical remounting
III. Facebow Registration:• Sufficient amount of wax is adapted on the prongs of
facebow fork
• The patient closes on the fork , facebow is then attached to the fork and related to the condylar heads
Why facebow???A facebow is used to record the relationship of the upper denture to the patient's mandibular hinge axis and transfer this to an articulator, using the hinge axis of the articulator as a reference.
If a facebow is used it allows the teeth to contact by rotating about an arc of closure identical to that of the patient.
A facebow is therefore often used to remount the processed dentures on an articulator for the correction of occlusal errors
Steps for clinical remounting
IV. Mounting Dentures in Adjustable Articulators• Fabrication of clinical remount casts:
Serve as an accurate, convenient and time saving method of reorienting the completed dentures on articulator for occlusal correction
All undercuts on the tissue surface of the dentures are filled with wet tissue paper, pumice
Steps for clinical remounting
Fast setting plaster or dental stone is poured into the denture
Steps for clinical remounting
The maxillary remount cast is attached to the maxillary member of the articulator using the facebow transfer jig
Steps for clinical remounting
Fabrication of the Facebow Transfer Jig
Attach upper processed denture to the upper
mounting ring
Pour fast setting plaster on the lower ring
Press the teeth in the plaster
Steps for clinical remounting
Mounting for Clinical Remount The remounting jig and the index are positioned on the
mandibular member of the articulator,
The maxillary denture and the remounting casts are placed in plaster indentation.
The maxillary cast is attached to upper member of the articulator with plaster
The lower denture is attached to the upper denture with help of wax interocclusal records
Steps for clinical remounting
The condylar guidance can be set with the help of protrusive and lateral records
After the plaster is set,the incisal guide pin is tightened and the record is removed ,there should be no contact of teeth
The incisal pin is then removed and occlusion is set by selective grinding procedure
Steps for clinical remounting
A simplified Chairside Remount Technique using Customized Mounting Platforms• This clinical remount technique utilizes maxillary and
mandibular CMPs (Customized Mounting Plates) that are fabricated over mounting plates of articulator..
Boxed mounting plates
6.5mm
2 mm 2.5mm
Chauhan et al J Adv Prosthodont. 2012 Aug; 4(3): 170–173.
Horseshoe shaped grooves
U-shaped positive replica of edentulous ridges with Acrylic (5-6mm)
Customized mounting platforms secured on articulator
Remount casts obtained in putty impression material.
Mounting done with centric interocclusal record.
V.Selective Grinding Procedure • In order to produce a satisfactory result, it is important
to carry out grinding in a systematic way to:oThe VD maintenanceo Even distribution of occlusal stresses in CO.o Even distribution of occlusal stresses maintained in
lateral position.
Steps for clinical remounting
• Hammer and Anvil concept:
As an aid in determining where on the teeth adjustments are to be made
Supporting cusps considered as HammerThe portion of tooth contacted by them as Anvil
The rule is,Adjust the anvil ,NEVER the hammer,thus
preserving our centric stops
The vertical dimension is controlled by these cusps ,therefore they should receive special
consideration
Bailey DCNA April 1995 39(2)
Grinding in Centric • The first objective is to remove premature contacts in
centric occlusion
• Mark the interfering cusps with articulating paper
• In the retruded contact position there are three types of occlusal errors and each can be corrected by specific grinding1. Any pair of antagonist teeth can be too long and thus
hold other teeth out of contact’2. The lower and upper teeth can be placed almost edge-
to-edge3. The upper teeth can be positioned too buccally in
relation to the lower teeth.
1. When cusps are too long:1.If the offending cusp makes premature contact in centric
as well as eccentric ground the cusp
2.If the offending cusp makes premature contact in centric only ,deepen the opposing fossa
2. The lower and upper teeth can be placed almost edge-to-edge
Broadnening the central fossae: LINGUAL inclines of the UPPER BUCCAL cusps and
BUCCAL inclines of the LOWER LINGUAL teeth are ground
Narrowing the cusps: Reducing palatal inclines of upper palatal cusps Reducing buccal inclines of lower buccal
3. The upper teeth positioned too buccally in relation to the lower teeth
The palatal cusp is ground in the palatal direction and the mandibular buccal cusp in the buccal direction so that teeth can enter each other.
Grinding in Eccentric • Free sliding eccentric movements are important to
Reduce stress on ridges Retention stability
Rule for eccentric grinding is ….Always adjust that which is moving
On the Working Side there are six types of Occlusal Errors
1. The maxillary buccal cusp and the mandibular lingual cusp are too long
2. The buccal cusps are in contact, but the lingual are not
3. The lingual cusps are in contact, whereas the buccal are not
4. The maxillary buccal or palatal cusps are positioned more mesially from their intercuspal position
5. The maxillary buccal or lingual cusps are positioned more distally from their intercuspal position
6. The teeth on the working side can be out of contact
1.The maxillary buccal cusp and the mandibular lingual cusp are too long The inner inclines of BUCCAL cusps of UPPER and
LINGUAL cusps of LOWER (BULL) are adjusted
2. The buccal cusps are in contact, but the lingual are not The lingual inclines of upper buccal cusps are ground
3. The lingual cusps are in contact, whereas the buccal are not Buccal inclines of mandibular lingual cusps are reduced
4.The maxillary buccal or palatal cusps are positioned more mesially from their intercuspal position(MU-DL) Mesial inclines of the UPPER buccal cusps Distal inclines of the LOWER buccal cusps
5.The maxillary buccal or lingual cusps are positioned more distally from their intercuspal position maxillary cusps distally and on the mandibular cusps mesially
6. The teeth on the working side can be out of contact This is because of intense contact on the balancing side
Occlusal Errors on the Non-working side• Mandibular buccal cusp are adjusted to reduce the incline of
the part of the cusp that prevents tooth contacts on the working side
Occlusal Errors in Protrusion• Accoroding to Boucher If the lateral eccentric contacts are
corrected the protrusive grinding also have been accomplished
• However,premature contacts on the incisors are corrected at expense of Incisal edges of lower anteriors
Perfecting Articulation with Grinding Paste• The main correction of occlusal irregularities must be carried
out using a small mounted abrasive stone in a hand piece to maintain VDO
• A paste of coarse grit carborundum powder mixed with Vaseline/toothpaste is used followed by fine grit carborundum to produce the even occlusal contacts
• The sharp edges occurring buccally and lingualy must be rounded to prevent tongue and cheek irritation
Eliminating Occlusal Errors in Non-Anatomic Teeth• Maxillary posterior are flattened by sanding on ultrafine
sand paper against a truly flat surface
• After placing on the remount casts and articulation,occlusalcontacts are marked
• Selective grinding is done only on the mandibular teeth
Occlusal Adjustment in Average Value Articulator• Using a simple hinge articulator is not satisfactory, as lateral
excursions are not possible
• The retruded contact position is recorded intraoral using soft wax
• The upper denture is articulated so that the center pin, touches the mid-line at the upper incisal edge.
• The lower denture is attached to the articulator ensuring that the occlusal plane is horizontal and parallel to the base of the articulator
• When the plaster has set, the wax is removed between the occlusal surfaces of the teeth and the occlusal adjustment is carried out
Full Dentures Opposed to Partial Dentures• When maxillary complete dentures and mandibular partial
dentures: Lower impression with the partial denture in situ When casting the impression RPD must be retained in it Similar procedures as previously mentioned are carried out Avoid grinding natural teeth
Partial Upper an Lower Dentures
• For maxillary and mandibular distal extensions with only anterior teeth remaining previously described procedures can be carried out
• For small partial dentures,the opposing natural dentition is adjusted
Conclusion • Correct occlusal relationships are a part of the success in
prosthetic treatment for edentulous patients with complete dentures.
• A clinical remount procedure of the finished dentures is a constituent part of prosthetic patient treatment in practice of complete dentures.
• According to a study done by Kamal Shigli et al the results indicated that the laboratory and clinical remount procedures,along with occlusal corrections, reduced the number of areas of tissue irritation, postinsertion visits, pain during mastication and swallowing, and discomfort during mastication, and enhanced the comfort of the patient
• The clinical remount also maintains the stability of dentures when the mandible is in centric relation position
• Selective grinding helps to remove the occlusal errors in a systematic way
• Occlusion of such dentures is more stable for longer time and with less parafunctional movements
and Hence, a more Satisfied Patient
References :
• Syllabus of complete Dentures ;Heartwell 4th edition
• Prosthodontic Treatment for Edentulous Patients ;Zarb,Hobkirk et al 13th edition
• Dental Laboratory Procedures volume 1 ;Rudd and Morrow
• Fenn, Liddelow, and Gimsons' clinical dental prosthetics
• Bailey et al Occlusal Adjustment ; DCNA april 1995 ;39(2)
• Chauhan et al A simplified chairside remount technique using customized mounting platforms; J Adv Prosthodont. 2012 Aug;4(3): 170–173.
• Tomislav Badel et al Complete Denture Remounting Acta StomatolCroat, Vol. 35, br. 3, 2001.
• Kamal Shigli The effect of remount procedures on patient comfort for complete denture treatment J Prosthet Dent 2008;99:66-72
• Lang et al ;Complete Denture Occlusion ;DCNA 2004 48 :641—665