Impression Procedures in CD- KIRTI SHARMA

Our first impressions whether of person or

things have great influence on all our future estimates

& opinions

IMPRESSION TECHNIQUES IN VARIOUS COMPROMISED

CONDITIONS IN PROSTHODONTICS

Capt Kirti Sharma

Maj Manish Mittal

Impression:- A negative likeness or copy in reverse of the

surface of an object. GPT-8

“ IMPRESSION SHOULD BE IN THE MIND OF THE DENTIST BEFORE IT IS IN HIS HANDS ``

• Preservation of

tissues

• Retention

• Esthetics

• Stability

• Support

PRINCIPLES OF IMPRESSION MAKING

• Condition 1 : Patients with special needs . Medically Compromised Highly Anxious or Dental Phobic Mentally Disabled Physically Disabled

Autistic, Cerebral Palsy, Down Syndrome Emotionally Disturbed, Behavior Problems

OR

Any patient who requires a little extra care from their dentist 

• Oral sedation with Triazolam or Midazolam oralsyrup in conjunction with the use of Papoose boards for physical restraint was probably one of the more contentious approaches to patient management.

• Empathy / sympathy for the patient .

Condition 2 : Gagging / hyperactive gag reflex

• Gag reflex is a complex physiologic phenomenon, protective in nature.

• Trigger areas: five areas of maximum sensitivity

- fauces

- base of tongue

- palate

- uvula

- posterior pharyngeal wall

Management Of The Gagging Patient

• Distraction Maneuvers

1. Engage him in some topic of special interest

2. Distract the patient by asking him to breathe deeply through nose

3. Hypnosis can also help in some instances

4. Krol suggested raising the right foot

• Prosthodontic management –

1. Avoid unduly overextended trays ,especially in posterior palatal region

2. Avoid loading excess material onto the tray

3. Have the patient sit in an upright position leaning forward with the head tilted slightly downwards

4. Use mouth temperature waxes – impression material

MARBLE TECHNIQUE – Singer developed a common sense approach to the problem of accustoming ‘hopeless gaggers’ to complete denture prostheses. First visit - Five round, multicolored, glass marbles, approx ½ inch in diameter.Second visit – pt assured that he can wear dentures.

Pharmacological Management-1. Local anesthetic gels can reduce some of the

sensations.2. Antihistamines, sedatives, tranquilizers have all

been tried with varying results

• Third visit

• Fourth visit – lower denture base ( training bead) + 3 marbles

• Fifth visit - maxillary denture base inserted .

• Sixth visit – maxillary rims placed + further treatment carried on.

Condition 3: Highly mucous saliva

• Small voids in the posterior palatal surface are due to mucous secretions from the palatal salivary glands.

• Wipe the palatal surface with gauze immediately before making impressions

Conditions 4: Xerostomia• Use of saliva substitues / lozenges/ salivary stimulants like

Cevimeline ,pilocarpine and bethanechol . Amifostine delivered as a daily three-minute intravenous infusion.

• Preliminary impressions with thermoplastic compound to deliberately overextend in retromylohyoid areas.

• Border-mold custom tray 1. Employing thermoplastic compound to ensure maximal

extension without muscle impingement. 2. Particular attention paid to optimizing not just length but also

width in the retromylohyoid and tuberosity areas.

• Final impressions with a free flowing material, such as light-bodied polyvinylsiloxane or polysulfide impression material.

• PRECAUTION – DELAY routine dental treatment in pts with active radiation / chemo therapy – 4-12 months.

Condition 5: Allergy to eugenol- contact dermatitis

• Apply vaseline before making impressions .

• Use light body elastomeric material.

• Eugenol allergy in some patients (o-ethoxy benzoic acid [EBA] to replace eugenol) OR use cavex .

Condition 6 : Flabby ridges

• Fibrous ridge or flabby ridge is a superficial area of mobile soft tissue affecting the maxillary or mandibular alveolar ridges

• Open-Window Impression Technique ( David J Lamb) This technique is used for displaceable maxillary ridge often termed as flabby.

• Tray correction

• Secondary impressions

• Reinsert the tray and apply a mix of impression plaster over the flabby tissue, which lies in the window.

• Recovered impression

Lynch and Allen in 2006

Primary impression - alginate.

A custom tray - 3 uniform thickness of wax spacer over the displaceable tissue and 1 thickness of wax

spacer over the non displaceable tissue.

border moulding + secondary impressions - heavy body impression

flabby tissue - light body impression material.

Condition 7 : Unemployed mandibular ridges

• Presence of a thin, mobile thread-like ridge which is essentially fibrous in nature

• The periphery of this compound impression is trimmed and border molding is done with green stick until it is retentive in the mouth.

• The compound over the ridge is then cut until the tray and the holes are exposed.

• Heavy digital pressure to transfer as much of the load as possible to the peripheral parts of the denture bearing area.

• The impression recorded mucostatic over the crest of the ridge. mucocompressive on the peripheral parts.

Condition 8 :Flat (atrophic) mandibular ridge covered with atrophic mucosa.

(McCord and Tyson)

The impression medium here is an admix of 3 parts by weight of (red) impression compound to 7 parts by weight of greenstick; the admix is created by placing the constituents into hot water and kneading with vaselined,gloved fingers.

Condition 8: Highly resorbed mandibular ridges (Tallgren)

preliminary impression - alginate.

custom tray without wax spacer.

1mm of resin is removed from the crest of the ridge.

final impression elastomeric material.

FUNCTIONAL IMPRESSION USING A CHAIR SIDE RESILIENT LINING MATERIAL ( LOCAL AREAS OF MODIFICATION)

Using soft liners / tissue conditioners

NEUTRAL ZONE

• The neutral zone is that area within the potential denture space where the forces of the tongue pressing outward are neutralized by forces of the cheeks and lips pressing inward.

• The technique of recording the denture space is sometimes known as piezographics( record shapes by means of pressure)

Technique

Modification of denture base

Movements to be done by the patient

Recorded neutral zone

Plaster index

CONDITION 11:Patient With Limited

Mouth opening

Scleroderma, orofacial malignancies, surgery, burns and TMJ ankylosis.

SECTIONAL SPECIAL TRAY FOR MAKING IMPRESSION

Cylindrical Metal Pins Are Inserted In The Two Halves Of Special Tray With A Flexible Plate Holding The Pins & Two halves Of Tray Together

Sectional perforated plastic stock tray – dentulous patients

Locked at the handle region with steel pins into tubings and acrylic hook into bent handles.

Sectional tray joined by acrylic hook or lock

Approximated with the aid of nick and notch

Sectioned into larger and smaller sections and joining done with three Lego building blocks 

Use of pins and acrylic plate

Nick and notches at the handle region only 

Mandibular sectional tray with steel burs and acrylic blocks

Anterior and posterior tray sections joined by steel burs 

MAXILLOFACIAL PROSTHODONTICS

Primary Impression - Irreversible Hydrocolloid

BORDER MOULDING OF NORMAL UNOPERATED SIDE

SPECIAL TRAY WITH SPACER & BORDERS MOULDED WITH LOW FUSING IMPRESSION COMPOUND

AFTER REMOVAL OF SPACER & PLACEMENT OF ESCAPE HOLES,THE DEFECT AREA IS RECORDED WITH PUTTY ELASTOMERIC IMPRESSION MATERIAL

FINAL IMPRESSION – light body elastomer / waxes / soft liners.

Conclusion

• The choice of impression material & impression technique along with the Experience of the clinician play a key role in obtaining desired results. The dentist should be able to cope with the conditions of basal tissues as presented by each patient and try to make the best impression s possible even in the most compromised conditions.

REFERENCES

1. Mc Cord et al. The design and use of special trays in prosthodontics: guidelines to improve clinical effectiveness. BDJ 1999; 187;423-426.

2. Mc Cord and Grant. Impression making. BDJ 2000;188;484-492

3. Hegde c, Prasad k , Prasad a, Hegde r .Impression tray designs and techniques for complete dentures in cases of microstomia—A review.J Prost Res 2012;56:142-146.

4. James Pavlatos, Kathryn Kamish Gilliam Oral care protocols for patients undergoing cancer therapy.General Dentistry, July-August 2008Pg. 464-478

5.Crawford and Walmsley. A review of prosthodontic management of fibrous ridges. BDJ 2005;199;715-719

6. Lynch and Allen. Management fo the flabby ridge.BDJ 2006;200;258-261.

7. Problems and solutions in complete denture prosthodontics. David Lamb

8.Essential of complete denture prosthodontics Sheldon Winkler.9. Textbook of complete dentures Charles M Heartwell10.Prosthodontic treatment for edentulous patients

Zarb bolender