TRIPASS XR تري باس

 

• To correct this error, the upper buccal cusp and the lower lingual

cusp on the working side are reduced

• By doing this, the lingual inclines of the upper buccal cusp and the

buccal inclines of the lower lingual cusp are made less steep

• Grinding of the central fossa is avoided

FIGURE 10-10 Heavy contact on balancing side.

Selective grinding procedure of nonanatomic

teeth

• Gross premature contact in centric relation is removed by using an

articulating paper.

• Occlusal interferences are detected in the lateral and protrusive

movements.

• Selective grinding is done on the occlusal surfaces of the teeth that

have been tipped or elongated during processing.

• In eccentric position, grinding is not done on the distobuccal portion of

the lower second molar.

• On the balancing side, all grinding is done on the lingual portion of

the occlusal surface of the upper second molar.

• Abrasive paste can be placed on the teeth on the articulator and the

lateral and protrusive movements are initiated.

• The abrasive paste mills the interfering contact and the procedure is

continued till smooth gliding movements of teeth are achieved in all

excursions.

• Spot grinding may be required to eliminate small discrepancies in

centric relation after grinding with abrasive paste.

• Small discrepancies are identified using articulating paper or tabulator

ribbon and selectively grinded.

Intraoral methods to correct occlusal

disharmony

Some of the commonly used methods are described below.

Articulating paper

• Using the articulating paper alone does not give accurate indication

of the premature contact.

• Resiliency of the tissues sometimes allows the dentures to shift

which may produce false result with the articulating paper.

• When the articulating paper is placed on one side, the patient can

shift the jaw close to or away from the side.

• Placing articulating paper on both sides of arch simultaneously may

sometimes be difficult.

Central bearing device

• Correlator which is a type of central bearing device with a spring is

used to detect occlusal prematurities.

• Pin attached in the mandibular mounting contacts with the metal

plate attached in the vault of the maxillary denture.

• The interceptive occlusal contacts are located with articulating

ribbon.

• Patient cooperation is very important.

• Coble device without the spring can also be used.

Occlusal wax

• Adhesive green wax is placed over the mandibular denture and the

patient is instructed to close in centric position.

• Points of penetration on the wax that occurs upon closure of the

jaws are detected and marked with lead pencil and relieved.

• Interferences can also be located in functional movements.

• However, chances of false markings are high during functional

movements as shifting of the dentures can take place over the

resilient tissues.

• This is an excellent method to detect occlusal prematurity in centric

position only.

Abrasive paste

• Abrasive paste when used over the occlusal surfaces of the teeth

mills the cuspal inclines to remove the premature contact.

• Shifting of the base as a result of premature contact results in

altering the occlusion.

• Cusps that maintain the occlusal vertical dimension may be

destroyed.

• This type of paste is not selective.

Postinsertion instructions to denture patients

Patient education regarding the limitations of the denture as artificial

prosthesis simulating natural tissues is started from the first

appointment. Still at the time of denture insertion, many instructions

are given to the patient.

Appearance with new dentures

• Patient must be educated that appearance with the new dentures

will become more natural with time.

• Initially, the dentures may feel bulky and give a feeling of the

fullness in the lips and the cheeks.

• With the passage of time, the lips and cheeks will adapt to the

fullness of the dentures.

• Muscle tension will improve after the patient becomes more relaxed

and self-confident.

• The patient is instructed not to compare his/her denture with others.

• Also, they should be advised to avoid exhibiting their dentures to

curious friends until they are confident.

Mastication with new dentures

• It will take at least 6–8 weeks for the new denture patient to chew

satisfactorily.

• Time is required for the establishment of new memory patterns for

both the facial muscles and muscles of mastication.

• The muscles of the tongue, cheeks and the lips must be trained to

keep the denture in place over the ridges during mastication.

• Initially, there will be excessive salivation with new dentures.

• Within few days, the salivary glands accommodate to the presence

of the dentures and the production of saliva.

• The patient is instructed to chew soft food from both sides of the

mouth.

• Hard food should be avoided till the time the patient adjusts with

the new dentures.

• The patient should be discouraged to incise the food between the

anterior teeth in front of the mouth.

• He/she is instructed to put the food towards the corner of the

mouth.

• The patient is informed about the role of tongue in the stability of

lower denture during mastication.

Speech with new dentures

• Speaking normally with new dentures requires practice.

• The patient is encouraged to read loud and repeat words or phrases

that are difficult to pronounce.

• They are encouraged to read newspaper aloud in front of the mirror

to master speech.

Oral hygiene instructions

• The patient is educated on the importance of maintaining good oral

hygiene.

• The patient is instructed to brush dentures at least twice daily and

rinse dentures after every meal, whenever possible.

• Dentures are cleaned with a soft brush using liquid soap or

toothpaste with low abrasion.

• Dentures should be brushed over the washbasin which is partially

filled with water or covered with wet cloth to prevent breakage of

denture on accidental dropping.

• Denture cleansers can be advised to remove stains from the

dentures.

• The mucosal surface of the residual ridges and the dorsum of the

tongue should be brushed daily with a soft brush.

Preserving residual ridges

• The patients are discouraged to wear the dentures during the night.

• They are educated on the importance of rest to the tissues.

• The patients are instructed to keep the dentures in a container filled

with water to prevent drying and possible dimensional changes of

the denture base materials.

• The dentures should be removed to provide rest to the tissues

during night-time.

• The patients should also be discouraged on the continuous use of

denture adhesives and home reliners.

• The patients are educated on the need for periodic recalls.

Educating materials for patients

• The patients should be given written instructions about the

dentures, preferably in the patient’s language.

• The patients should be advised to read book or pamphlet regarding

the care of dentures.

Troubleshooting in complete denture prosthesis

and its management

Troubleshooting in complete denture prosthesis can be caused by

either of the following factors:

• Adverse intraoral anatomical factors (e.g. atrophic mucosa)

• Clinical factors (e.g. poor denture stability)

• Technical factors (e.g. failure to preserve the land area on the master

cast)

• Patient adaptational factors

All of the above-mentioned factors are important but by far the

patient adaptational factor is the most critical. Some patients are

positive with the treatment and some find it difficult to adapt to the

new prosthesis physically and psychologically. It is important to take

proper history and accurately diagnose the problem individually.

Troubleshooting in complete dentures usually arises after insertion of

the new dentures.

Troubleshooting can be broadly divided into the following categories:

(i) Discomfort or pain with the dentures

• Discomfort related to impression surface of

dentures (Table 10-4)

• Discomfort related to the occlusal and polished

surfaces of dentures (Table 10-5)

• Discomfort related to possible systemic factors

(Table 10-6)

(ii) Looseness of the denture

• Due to decreased retentive factors (Table 10-7)

• Due to increased displacive factors (Table 10-8)

(iii) Inability to adapt to dentures (Table 10-9)

TABLE 10-4

DISCOMFORT WITH DENTURES RELATED TO IMPRESSION

SURFACE OF DENTURES

Symptom(s) Cause(s) Treatment

Discrete painful areas Pearls or sharp ridges of acrylic on

impression surface

Use disclosing

material and relieve

Pain on insertion and removal Denture is not relieved in the region of

undercuts

Use disclosing

material and adjust

in the region of ‘wipe

off’

Areas painful to pressure Faulty impression, damage to master cast,

warpage of denture base, lack of relief to

active frena, nondisplaceable mucosa over

the bony prominence

Use disclosing

material to

accurately locate area

to be relieved

Pain on swallowing Overextended lower denture Determine extent

and location of

overextension and

relieve accordingly

Generalized pain over the denturebearing areas

Underextended denture base due to

overadjustment to the periphery

Extend denture to

optimal available

denture support area

Lack of relief for frenum, muscle

attachments, pinching of tissues

between the denture base and

retromolar pad or tuberosity

Peripheral overextension resulting from the

impression stage and design error

Relieve with aid of

disclosing material

Sore throat, difficulty in swallowing Posterior palatal area is too deep Removal of existing

seal and replacement

with new material is

required

TABLE 10-5

DISCOMFORT RELATED TO THE OCCLUSAL AND POLISHED

SURFACES OF DENTURES

Symptom(s) Cause(s) Treatment

Pain on eating, in

the presence of

occlusal imbalance

Anterior or posterior premature

contacts, lack of balanced occlusion

Detect occlusal prematurity and adjust by

selective grinding; if the error is severe, take

new interocclusal record and remount

Pain lingual to the

lower anterior ridge

If no overextension is present, look for

protrusive slide from the centric

Detect deflective occlusal inclines of posterior

teeth and adjust by selective grinding

relation to centric occlusion

Pain or

inflammation of

labial aspect of

lower ridge

Lack of overjet Reduce the overbite; if appearance is

disturbed, rearrange the incisor

Pain in the

periphery of

dentures

VDO is more If VDO is less than 1.5 mm, adjust by

selective grinding; if more than 1.5 mm,

rearrange teeth at proper VDO

Cheek and/or lip

biting

For cheeks: The functional width of the

sulcus was not restoredFor lips: Poor

lip support/inadequate overjet

For cheeks: Restore functional width of

sulcusFor lips: Grind lower incisor to alter the

incisal guidance

Tongue biting Teeth placed in the tongue space more

lingually

Remove lower lingual sulcus or reset teeth

Pain at the

posterior region of

upper denture on

opening

Distobuccal border of the upper

denture is too thick and constraining

the coronoid process

Use disclosing material to accurately define

area involved; relieve and polish

TABLE 10-6

DISCOMFORT DUE TO POSSIBLE SYSTEMIC FACTORS

Symptom(s) Cause(s) Treatment

Burning sensation over the upper

denture-bearing areas

Burning mouth

syndrome seen in

middle age or elderly

patient

Correction of any denture faults, may require

multivitamin drugs, nutrition and medical

advice

Beefy red tongue Vitamin B12

/folate

deficiency

Seek medical advice

Frictional lesions related to

dentures, complain of dry mouth

Xerostomia, side

effect of prescribed

drugs

Advise citrus lozenges or artificial saliva

Tongue thrusting; empty mouth

chewing seen in elderly

Neurological or

psychological aspect;

can be drug related

Difficult to manage; seek medical advice

Presence of herpetiform ulcers in

the mouth

Herpes simplex or

herpes zoster virus

Suggest preventive remedy (e.g. acyclovir) but

with medical advice

Clicking of the TMJ on opening

and/or closing mouth with or

without tenderness

TMJ pain dysfunction

syndrome may be

related to rapid

change of VDO

Careful correction of vertical dimension of the

dentures

Painless erythema of mucosa

related to the support of upper

denture may be accompanied with

angular cheilitis

Denture-related

stomatitis, ill-fitting

denture with candidal

infection

Rest to tissue; correct denture problem using

tissue conditioners and occlusal pivots; for

angular cheilitis advice antifungal and

antibacterial agents

Note: TMJ = temporomandibular joint.

TABLE 10-7

LOOSENESS OF DENTURE RELATED TO DECREASED

RETENTION FORCES

Symptom(s) Cause(s) Treatment

Lack of peripheral seal Underextended borders in depth and

width

Relining of the dentures

Inelasticity of the cheek

tissues

Consequences of ageing process,

scleroderma, mucous fibrosis

Border moulding is done in

increments using softened tracing

compound

Xerostomia – reduces

ability to form adequate

seal

Side effects of drugs, patient on

radiotherapy, salivary gland disease

Dentures designed to maximize

retention and minimize displacing

forces; artificial saliva can be

prescribed

Speech and eating

difficulties

Lower posterior placed lingually, occlusal

plane too high, upper posterior placed too

far buccally, lingual flange of lower

convex, reduced neuromuscular control

Correct design faults, denture

adhesives may be prescribed

Denture rocking, gap

between the periphery of

flange and ridge, occlusal

errors subsequent to

warpage

Deficient impression, damaged master

cast, warped denture, overadjustment of

impression surface, residual ridge

resorption, excessive relief

Reline if design is satisfactory,

ensure areas of heavy contact

between the denture and tissues

are relieved before impression

making

TABLE 10-8

LOOSENESS OF DENTURE RELATED TO INCREASED

DISPLACING FORCES

Symptom(s) Cause(s) Treatment

Overextended denture borders

in depth and width, slow rise of

lower denture when the mouth

is half-open, line of

inflammation at reflection of the

sulcus tissues, deep postdam on

upper denture base

Thickened lingual flange causes tongue to

lift the denture, thick upper and lower

labial flanges may produce displacement

during muscle activity

Relieve the overextensions;

check borders of the record

rims and trial dentures at

the appropriate stages

Poor fit to supporting tissues Poor impression Reline if design is

satisfactory

Denture not in optimal space Molars on lower denture are placed

lingually, posterior occlusal table too broad

causes tongue biting, thick lingual flanges

encroaching in tongue space, excessive lip

pressure to lower anterior aspect, excessive

pressure from upper lip to the denture in

anterior aspect

Remove lingual cusp and

lingual surface and

repolish or reset or remake

the dentures, reshape

lingual polished surface,

thin lower labial flange or

remake the dentures

Occlusal errors Uneven tooth contacts causing tilting of the

dentures

Centric relation and centric occlusion does not

coincide

Lack of freedom in centric

Adjust occlusion until even

initial contact in centric

position is

obtainedOcclusion

adjusted to coincide centric

occlusion with centric

position

Remount dentures on

articulator and adjust area

of occlusal contact, allow

freedom of movement

from the centric position,

use nonanatomic teeth, if

required

Ulceration labial to lower ridge Excessive overbite, lack or balance and

lower anterior tooth contact cause tilting

and soreness of lower ridgeLast molar is

placed too far over the retromolar pad

Occlusal plane is not oriented appropriately

and masticatory forces tend to move

dentures over the supporting tissues

Reduce height of lower

anteriorsRemove the

posterior teeth from

dentures and reset

Usually requires teeth to be

reset or dentures remade

Bony prominence covered by

thin mucosa

Denture rocks over the prominence which

may be covered with inflamed tissues

Use disclosing paste and

relieve the denture

accordingly

Fibrous displaceable tissue Masticatory forces tend to cause the denture

to sink and tilt into the supporting tissues

Reline using low viscosity

material and provide many

vents, maximize posterior

border seal

TABLE 10-9

INABILITY OF PATIENT TO ADAPT TO DENTURES

Symptom(s) Cause(s) Treatment

Clicking of dentures Excessive VDO, occlusal

interference, may lack skill with

new denture, loose dentures

Patient education, relieve occlusal interference,

adjust vertical or remake the denture

Difficulty in eating,

denture moves on

supporting tissues

Unstable dentures Construct new denture

Jaws close too far Decreased VDO May increase up to 1.5 mm by relining or else

remake

Speech problems,

cannot open mouth

widely, facial pain

over masseter

Excessive VDO Can remove up to 1.5 mm or else remake

Speech problems Cause may not be obvious Check the vertical dimension, check positioning

of the teeth, excessive palatal contour

Gagging Loose dentures, thick distal border

of upper denture, low occlusal

plane, palatal placement of upper

posterior teeth

Construct new dentures

Too much visibility

of teeth

Level of occlusal plane

unacceptable, poor lip support

Reset teeth or remake

Creases at the

corners of the mouth

VDO decreased, labial fullness and

anterior tooth position inaccurate

Adjust correct tooth position, re-register jaw

relation

Colour of denture

base unnatural

Denture base not characterized to

individual needs

Rebase with suitable material

Appearance not

satisfied

Patient failed to comment during

try-in, change from old denture to

new is sudden, influenced by

Accurate assessment of the patient’s aesthetic

requirements, ample time with the patient

during try-in, use available evidence such as

relatives photographs to assist

Denture cleansing agents

Denture cleansers are aids used in maintaining complete denture

hygiene. It is important for the patient to practise denture hygiene

regularly for better success of complete denture treatment.

Denture cleansers can be divided into the following categories.

Chemical cleaning agents

• Safe and effective denture cleansing agent should be used by the

patient.

• Many denture cleansers have strong bleaching agent in them and if

used regularly for long, can cause discolouration of the denture

base and teeth.

• Inexpensive, safe and effective denture cleansing solution has been

suggested by Buffalo School of Dental Medicine, New York.

• This solution consists of 1 teaspoon of sodium hypochlorite, 1 teaspoon of

calgon and 4 ounces of water.

• Sodium hypochlorite provides bleaching action to remove stains from

the dentures and is also an effective germicidal agent.

• Calgon is a water softener, which by its detergent action loosens food

deposits on the denture.

• The patients are instructed to wash the denture with soft brush

under running water after chemical soaking.

• White vinegar can also be used overnight to remove calculus deposits

over the surface of denture.

• Acetic acid present in white vinegar helps in decalcifying the

calculus deposits on denture.

Mechanical cleaning agents

• Soft denture brush, soap or denture cleansing paste and water are used

effectively to clean dentures.

• Hard denture brush should be avoided, as it abrades the teeth and

the denture.

• Gentle brushing with nonabrasive detergent or paste is

recommended for effective denture cleansing.

Sonic cleaners

• These are new denture accessories.

• Sonic cleaners employ vibratory energy and not ultrasonic energy to

clean the dentures.

• Sonic cleaners effectively remove calculus from the dentures.

• It is also observed that sonic cleaner when used with sodium

hypochlorite is more effective than when sodium hypochlorite was

used alone.

Key Facts

• An occlusal pivot is an elevation placed on the occlusal surface of

the molars to limit the mandibular closure by acting as a fulcrum.

• The occlusion of the complete denture should be checked after 24 h.

• Burning sensation of the anterior palate in a new denture wearer is

due to insuf icient relief of the incisive papilla.

• Midline fracture of the dentures is mainly because of thick frenum

not relieved in the denture, wide deep notch in the midline, teeth

set too far buccally and excessive resorption.

CHAPTER

11

Relining and rebasing

CHAPTER OUTLINE

Introduction, 189

Definition, 189

Rationale for Relining Complete Dentures, 190

Problems Associated with Relining

Procedures, 190

Preparation of the Tissues, 190

Preparation of Dentures, 190

Techniques of Relining, 190

Open Mouth Relining Technique, 190

Closed Mouth Relining Technique, 191

Rebasing, 194

Procedure, 194

Advantages of Rebasing Over Relining, 195

Disadvantages, 195

Introduction

Residual alveolar ridges tend to resorb with time at variable rate in

different individuals. The rate of ridge resorption is higher in females

than in males. With resorption, the adaptation of the denture with the

tissues is altered and hence it requires continuous maintenance.

Relining and rebasing are two techniques which are used to maintain

adaptation of the dentures to the tissues.

Definition

Relining is defined as ‘the procedures used to resurface the tissue side of a

removable dental prosthesis with new base material, thus producing an

accurate adaptation to the denture foundation’. (GPT 8th Ed)

Rebasing is defined as ‘the laboratory process of replacing the entire

denture base material on an existing prosthesis’. (GPT 8th Ed)

Indications for relining or rebasing

• Immediate dentures which were made 3–6 months before

• Poor fit of the denture base to the ridges because of resorption

• The patient cannot afford remaking of the dentures

• When mental or physical health of the patient does not permit

fabrication of new dentures

Contraindications

• If ridges are excessively resorbed

• If the soft tissues are highly abused

• Patients with temporomandibular joint problems

• Major alteration in speech

• Poor aesthetics

• Severe bony undercuts

• Unsatisfactory jaw relationship

Advantages

• Reduced patient visits

• Economical for patient

• Fit of the prosthesis is improved

• Soft liner can be used, if needed

Disadvantages

• Not used in case of excessive resorption

• Chances of altered jaw relationship during the process

• Cannot correct occlusal arrangement

• Cannot alter aesthetics or jaw relations

Rationale for relining complete

dentures

• To re-establish the correct relation of the denture to the basal tissues

• To restore the lost occlusal and maxillomandibular relationships

• To restore retention and stability of the denture

Problems associated with relining

procedures

• Denture base almost always becomes thicker after relining.

• Maxillary denture is displaced anteriorly and, therefore,

oversupports the lips after relining.

• Plane of occlusion may be altered.

• It may result in colour difference between the original denture base

and the new relining material.

Relining is the procedure of adding additional acrylic resin to the

tissue surface of the original denture base to replace the lost oral

tissues.

Preparation of the tissues

• Excessive hyperplastic tissues should be surgically removed.

• Any irritating cause to oral mucosa is removed.

• Adequate rest to the supporting tissues.

• Dentures are left out of mouth for at least 2–3 days before making

final impressions.

• Daily massage of soft tissues is recommended.

Preparation of dentures

• Pressure areas in the denture should be relieved.

• Minor occlusal prematurities are removed by selective grinding

procedure.

• Correct posterior palatal seal should be established.

• Minor border inadequacies, if any, are corrected.

Techniques of relining

Open mouth relining technique

Carl O. Boucher’s Reline method (1973)

• Existing dentures are used as recording bases.

• Jaw relation is recorded after making maxillary and mandibular

final impressions.

• In the maxillary denture, posterior palatal seal is recorded with

modelling plastic.

• About 1 mm of space is provided in the tissue surface of the

denture.

• The denture borders are reduced by 1 mm to allow space for impression

material to form a new border.

• Similarly, the denture borders and the tissue surfaces of the lower

denture are reduced by 1 mm.

• Modelling plastic handle is made over the anterior teeth to facilitate

handling.

• Adhesive tape is applied over the polished surface of the denture.

• Border can be moulded with modelling plastic.

• After this, zinc oxide eugenol impression paste is loaded over the tissue

surface of the dentures and placed in the mouth.

• The patient is instructed to pull his/her lip down and open his/her

mouth widely.

• These actions help the impression to be moulded over the border of

the denture.

Advantages

• Impression is made with selective pressure technique.

• It is possible to verify the centric relation record.

• Interocclusal record made with plaster is reliable.

Disadvantages

• This technique requires more clinical and laboratory time.

• This technique is difficult to master.

Closed mouth relining technique

1. F.W. Shaffer’s technique (1971)

• Centric relation is recorded before the impression is

made using modelling compound or wax.

• Denture is relieved in large undercut areas and 1.5–

2 mm from the tissue surface.

• Denture borders are reduced by 1–2 mm, except the

posterior border of the maxillary dentures.

• A large part of palatal portion of the maxillary denture is

removed to improve visibility of the maxillary

denture during impression making (Fig. 11-1).

• Border moulding is done using modelling plastic.

• Zinc oxide eugenol impression paste is used for

impression making.

• During border moulding and impression making,

the patient closes his/her mouth lightly into the

interocclusal record that was previously made.

• The impression of the exposed palatal portion of the

upper denture is made by quick-setting plaster.

Advantages

• Opening of the palatal portion of the maxillary

denture allows better seating.

• Premade interocclusal record helps in orienting the

dentures during impression making and mounting.

• Two-step impression procedure reduces the chances

of anterior shifting of the maxillary dentures.

Disadvantages

• Possibility of forward movement of maxillary

denture is there.

• Wax interocclusal record is not reliable.

• It is difficult to reline both dentures at the same

time.

2. N.J. Hansen’s technique (1964)

• Existing centric occlusion and intercuspation are

used as means to seat the dentures.

• Denture borders are prepared as in the abovedescribed technique.

• Even in this technique, palatal portion of the

maxillary denture is removed.

• The palatal portion is outlined and reduced to half

the thickness of the denture base.

• Holes are drilled at 5–6 mm interval inside this

groove and slowly the portion is removed (Fig. 11-

2).

• Green stick compound is used for border moulding.

• Impression is made with Kerr’s impression wax.

• Impression is made in two steps and the impression

of the labial flange and crest of ridge is made in the

second step.

Advantage

• Two-step impression technique reduces the chances

of extreme forward movement of the maxillary

denture.

Disadvantages

• It is difficult to manipulate the impression wax.

• Errors of existing centric occlusion can lead to

inaccurate impression.

3. J.F. Bowman’s technique (1977)

• Existing centric relation is used to seat the dentures.

• Denture is prepared as in the above-described

techniques.

• Labial and palatal flanges of the dentures are perforated.

• Perforation is made to decrease the pressure during

impression making.

• No specific impression material is recommended.

4. L.G. Jordon’s technique (1971)

• Existing centric occlusion is used to seat the

maxillary denture.

• Denture is prepared as in the above-described

techniques.

• Denture periphery is reduced to create flat border.

• A large opening is made in the palatal portion of the

maxillary denture.

• Adhesive tape is attached over the buccal and labial

surfaces of both dentures, 2 mm short of the denture

borders (Fig. 11-3).

• Using a knife-edged stone, deep grooves are cut

into the labial and buccal surfaces of the dentures at

the junction of the impression material and filled

with molten baseplate wax.

• Impression plaster or zinc oxide eugenol paste is used

for impression making for the first step.

• Impression plaster is used to make impression for the

second step.

Advantage

• Same as Shaffer’s technique.

Disadvantage

• Existing errors of centric occlusion can result in

faulty impression.

5. N.S. Javid et al. technique (1985)

• This technique is based on the use of tissue

conditioning material.

• The patient is instructed not to wear the dentures

overnight.

• Centric occlusion in the old denture is carefully

examined and if any error is detected, it is

corrected.

• The centric relation should coincide with the centric

occlusion.

• The denture borders and the tissue surface of the

denture are adequately reduced for tissue

conditioning material (Fig. 11-4).

• The surface is dried before impression material is

placed.

• Minimum thickness of tissue conditioning material

is placed over the tissue surface of the denture and

then inserted in the patient’s mouth.

• Once the material sets, the denture is removed from

the mouth and the excess material is trimmed using

sharp BP blade.

• The patient is instructed regarding care of the

relining material before dismissing him/her.

• When the patient returns after 3–5 days, the denture

is re-examined for denuded areas.

• Any denuded area is marked with indelible pencil

and the pressure areas are relieved before next

application of the tissue conditioners.

• The material is changed periodically within 1 week.

• This is done till the tissues return to clinically healthy

condition.

• At this time, the patient is scheduled for final

impression.

• All the tissue conditioning materials on the tissue

side are replaced by new ones.

• Zinc oxide paste or light body polysilicones can also be

used.

• Once the impression is satisfactory, it is poured

immediately.

• The maxillary cast is mounted on the semiadjustable articulator using facebow record.

• The mandibular cast is mounted using interocclusal

record.

• The relined dentures are replaced by the new

material.

• Dentures are finished and polished in conventional

manner.

• Dentures are inserted in the patient’s mouth and

occlusal interference, if any, is detected and

corrected by selective grinding.

FIGURE 11-1 Large parts of palatal portion are removed for

visibility.

FIGURE 11-2 Preparation of denture borders and palatal

portion of denture: (A) denture borders reduced by 2 mm; (B)

perforation in the palate.

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FIGURE 11-4 Tissue conditioners applied over the

impression surface of the denture.

Rebasing

Rebasing is defined as ‘the laboratory procedure of replacing the entire

denture base material on an existing prosthesis’. (GPT 8th Ed)

Indication and contraindication of rebasing are similar to relining.

Rebasing refers to the procedure of replacing all the denture base

materials with new ones.

Procedure

1. Jig Method (Fig. 11-5)

• Impressions are made and the cast is poured in the

denture.

• The cast with the denture is mounted on an

instrument such as Hooper duplicator.

• This instrument maintains the relationship of the

teeth to the cast.

• The original denture base is removed.

• The original teeth mounted in the duplicator are

rewaxed in their previous positions on the cast.

• Denture is then processed in the laboratory in

conventional manner.

2. Flask Method (Fig. 11-6)

• Impressions are made and the cast is poured in the

denture.

• Cast is not separated from the denture.

• The cast is placed into the lower half of the flask.

• The silicone mould material is painted over the

denture before investing. This creates a flexible

mould.

• Flasking is completed in conventional manner.

• The flask is opened, once investing is completed.

• Because of the silicone mould, it is easier to separate

the two parts of flask.

• Denture base is trimmed completely and the teeth

are replaced into the indentation.

• Separating medium is applied over the cast and the

mixed resin is packed into the space.

• Denture is cured, finished and polished in

conventional manner.

• Finished dentures are remounted to check for any

occlusal prematurities.

3. Articulator Method (Fig. 11-7)

• Impression is poured immediately.

• Maxillary cast is mounted on articulator using

facebow transfer.

• The mandibular cast is mounted using interocclusal

record.

• If occlusal discrepancy exists, it is identified and

corrected.

• The complete denture base is reduced leaving 2 mm

of acrylic around the teeth.

• The trimmed teeth are placed back on the

articulator and waxed without altering the vertical

dimension.

• The denture is then processed in conventional

manner.

FIGURE 11-5 Denture is indexed into Hooper duplicator.

FIGURE 11-6 Flask method.

FIGURE 11-7 Articulator method.

Advantages of rebasing over relining

• There is no colour difference between the old and new resin.

• Problem of release of strain from processing an old base is avoided.

• Thickness of the base is better controlled.

Disadvantages

• It has an additional laboratory step.

• There are chances of displacement of teeth during waxing-up.

Key Facts

• Tissue conditioners are used in functional reline technique.

• The major drawback of rebasing complete dentures is chances of

alteration in the centric relation.

CHAPTER

12