Quartz 4

L2 Patient Evaluation and Impressions

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Complete Dentures: Preclinical1

Patient Evaluation & Primary Impression

Note

This document outlines the essential steps for patient evaluation and the process of making primary impressions for complete dentures. A thorough examination is crucial before commencing any treatment to ensure the proposed plan is appropriate for the patient.

Complete Denture Overview2

Treatment Schedule

VisitOperatorProcedure
Visit 1Clinician
Laboratory		Patient evaluation & primary impressions
Diagnostic casts & special trays
Visit 2Clinician
Laboratory		Secondary impressions
Bead & box, master casts, base & rims
Visit 3Clinician
Laboratory		Contour rims, OVD, MMR, shade & mould selection
Articulation & tooth setting
Visit 4Clinician
Laboratory		Wax try-in
Finalisation & processing
Visit 5ClinicianAssessment & issue
Instructions for care
Visit 6ClinicianPost operative review, post insertion instructions

Patient Evaluation3

Note

A full dental examination must be completed prior to any treatment. This involves a comprehensive assessment of the patient’s medical and dental history, as well as detailed extra-oral and intra-oral examinations.

Medical History

  • General health
  • Current medications
  • Neuromuscular system (Stroke, Parkinson’s)
  • Nutritional disturbances
  • Blood dyscrasias
  • Allergies

Dental History4

How many years edentulous
Reasons for tooth loss
Difficult extractions? (possible retained roots)
Age of dentures
Repairs, relines, cracks or additions

  • ==Duration of Edentulism: How many years the patient has been without teeth.==
  • ==Reasons for Tooth Loss: Whether teeth were lost due to caries, periodontal disease, or trauma.==
  • ==Extraction History: Note any difficult extractions that might suggest the presence of retained roots.==
  • ==Denture History:==
    • Age of the current dentures.
    • History of any repairs, relines, cracks, or additions to the existing prostheses.

Extra-oral Examination5

  • Facial morphology

  • Check for any swellings, discoloration, or asymmetry.

  • Palpation of major lymph nodes

  • Aesthetic evaluation

  • Development of facial musculature

  • Skeletal base relationship

  • Lips (length, mobility, aesthetics)

  • TMJ activity

  • Observe activity during rest and mandibular movements.

    • Check for any pain, clicking, grating sounds, or limitation of movement/opening.
    • Note any deviations or deflections during opening and closing.

Intra-oral Examination6

  • Alveolar ridges
  • Oral Mucosa
  • Denture bearing area
  • Posterior palatal seal
  • Palate shape
  • Sulcus depth
  • Frena attachments (level, size & activity)
  • Inter-ridge space
  • Ridge relation
  • Saliva (type, quantity)
  • Tongue (size, activity, pathology)
  • Abnormalities (denture hyperplasia, tori)

Radiographic Examination78

{OPG +/- PA}

  • Unerupted teeth

  • Retained roots

  • Bone quantity and quality

  • TMJ

  • ==Guidelines: Current guidelines recommend against routine radiographic screening for all new complete denture patients. Radiographs should only be taken if indicated after a careful history and clinical examination.==

Pretreatment digital panoramic radiographs revealed very few abnormalities that influenced the treatment of patients requiring complete removable dental prostheses reinforcing current guidelines that recommend against radiographic screening of patients who seek new complete removable dental prostheses, unless indicated by a careful history-taking.

Kratz et al. 2017

Review of Existing Prostheses910

Existing dentures

  • Occlusal vertical dimension
  • Stability & retention
  • Peripheral extension
  • Occlusion / articulation
  • Aesthetics
  • Phonetics
  • Wear

Talk to the patient!

  • Identify chief complaints
    • Understand their real and perceived difficulties
  • Difficulties with adjusting to dentures
  • How many years with dentures
  • Beware of patient that presents with a collection of “unsatisfactory” dentures

Intra-oral Examination11

Alveolar Ridges

Info

The alveolar ridges are evaluated by the ratio of their width to their height.

  1. BC = AB = CA = Normal
  2. BC > AB = CA = Low
  3. BC < AB = CA = High

Oral Mucosa12

Info

A healthy oral mucosa is typically pink, smooth, moist, and resilient. Its health can be negatively affected by systemic and local factors.

Systemic factors

  • Old age
  • Diabetes mellitus
  • Nutritional deficiency
  • Malignancy
  • Immune defects
  • Medications:
    • Corticosteroids
    • Anti-cancer drugs

Local factors

  • Dentures:
    • Trauma
    • 24/7 usage
    • Poor hygiene
  • Xerostomia:
    • Sjogren’s syndrome
    • Irradiation
    • Drug therapy

Denture Bearing Area13

Note

The nature and extent of the denture-bearing area must be noted. The soft tissues should be palpated to determine their consistency (soft, firm, mobile, or flabby).

  • Maxillary Denture Bearing Area:
    • ==Boundaries: Labial frenulum, labial vestibule, buccal frenulum, buccal vestibule, hamular notch, and the posterior palatal seal.==
    • ==Anatomical Landmarks: Alveolar ridge, incisive papilla, maxillary tuberosity, palatal rugae, median palatine raphae, fovea palatini.==
  • Mandibular Denture Bearing Area:
    • ==Boundaries: Labial frenulum, buccal frenulum, lingual frenulum, labial sulcus, buccal sulcus, retromolar pads, and the retromylohyoid fossa.==
    • ==Anatomical Landmarks: Alveolar ridge, mylohyoid ridge.==

Posterior Palatal Seal1314

  • Posterior limit:
    • The distal demarcation of the movable and non-movable tissues of the soft palate.
    • (vibrating line) – usually ~ 2mm anterior to Fovea Palatini

Clinical Technique

To find the vibrating line, place a ball burnisher at the anticipated site and have the patient say

  • Anterior limit:
    • The junction of the hard and soft palates on which pressure, within physiologic limits, can be placed
  • Lateral extension:
    • Hamular notch

Palate Shape15

U-Shape

Ideal retention and stability

Most Favorable

Both alveolar ridges and the palate are firm and well-rounded.

V-Shape16

Less retention

Warning

Has a well-shaped ridge but a deep, narrow palatal vault. This shape requires adequate relief during secondary impressions.

Flat17

Reduced resistance to lateral forces

Least Favorable

A broad, flat palate offers reduced resistance to lateral displacing forces.

Sulcus Depth18

Shallow maxillary buccal sulci

Warning

Shallow sulci in both the upper and lower jaws provide reduced resistance to lateral displacing forces, which can lead to poor lateral stability of the denture.

Frena Attachments19

Note

These are the attachment points for the circumoral musculature. The height of the frenal attachments is assessed by gently stretching the lips and cheeks. Failure to accommodate high or very mobile frena is a common cause of denture displacement during facial movements.

Inter-Ridge Space20

Warning

A lack of adequate space between the upper and lower alveolar ridges in the rest position must be addressed either before or during denture fabrication.

Ridge Relationship21

Note

The relationship between the opposing alveolar ridges is noted. Significant differences in width must be managed during denture fabrication through appropriate tooth selection and arrangement.

Tongue Size & Activity22

Warning

An oversized or overactive tongue can cause denture displacement. In very severe cases, surgical reduction may be required, although this is rare.

Abnormalities23

Soft Tissue Disorders

  • ==Flabby Tissue:==
    • ==Management (Mild Cases): The secondary impression tray can be modified to relieve the flabby area, allowing occlusal forces to be resisted by nearby normal tissue.==
    • ==Management (Severe Cases): If the amount of flabby tissue is too large, pre-prosthetic surgery to remove the excess tissue may be necessary.==
  • ==Hyperplasias or Ulcerations: These conditions (e.g., denture hyperplasia) must be treated and the tissue allowed to return to a healthy state before final impressions are made.==

Management of excessive soft tissue

  • small excess – relieve area in impression
  • large excess — may require surgery

Hard Tissue Disorders

  • ==Tori: Bony growths, most commonly found on the palate (torus palatinus) or mandible (torus mandibularis).==
    • ==Challenges: They can pose significant problems for dentures due to their size, position, and thin tissue coverage.==
    • ==Management: Surgical removal is not always possible, especially in the palate, and may require innovative treatment planning solutions.==

Primary Impressions242526

Note

After the patient evaluation is complete, preliminary impressions of the jaws are made using stock impression trays loaded with an impression material.

Impression Materials27

ThermoplasticModelling compound
Chemical ReactionAlginate Impression Material
Plaster of Paris
DigitalIntra-oral scan
Extra-oral scan of impression or cast

Thermoplastic

  • ==Example: Modeling compound.==
  • ==Process: A hard material supplied in flat cakes that softens in a 55-60°C water bath. It is loaded onto a tray, inserted into the mouth, muscle-molded, and removed after it hardens upon cooling.==
  • ==Limitation: Cannot be used for impressions where significant undercuts are present.==

Chemical Reaction

  • ==Example: Alginate impression material.==
  • ==Process: A powder is mixed with a liquid to form a sol, which then sets via a chemical reaction into a flexible gel.==
  • ==Advantage: Being flexible, it can be used for impressions with undercuts.==

Digital Impressions (Scanning)

A newer alternative method for impression making.

  • Methods:
    • Directly scanning the mouth with an intraoral scanner.
    • Scanning a conventional impression or a cast.
  • Note: Direct scanning can have technical challenges, especially for inexperienced operators, but may become the standard as technology evolves.

Impression Materials28

Thermoplastic

Modelling Compound

55° -60°

Chemical Reaction29

Alginate Impression Material

Properties

  • Elastic
  • Hydrophilic
  • Irreversible set

Composition – by weight

  • Potassium alginate 12%
  • Diatomaceous earth 70%
  • Calcium sulphate 12%
  • Trisodium phosphate 2%

Component Roles

  • Potassium or Sodium Alginate: The reactive component.
  • Diatomaceous Earth: Acts as a filler.
  • Calcium Sulfate: The reactor.
  • Trisodium Phosphate (2%): The retarder, which controls the working time.

Setting Reaction

  1. ==When the powder is mixed with water, the calcium sulfate first reacts with the trisodium phosphate (retarder). This initial reaction allows for adequate working time.==
  2. ==Once all the retarder is consumed, the remaining calcium sulfate reacts with the potassium/sodium alginate.==
  3. ==This second reaction forms an insoluble calcium alginate gel, which is the final set material.==

Alginate Impression Material30

Tray Selection

Disposable Trays

  • Edentulous – with handle

Note

Disposable trays are generally made from plastic. They are preferred over reusable metal trays, which are considered uneconomic due to the need for laborious cleaning, autoclaving, and sterile storage.

  • Mouldable – with handle
  • Polytray – with removable handle
  • Current OHCWA stock

Tray Modification31

Info

Stock trays often require modification to fit edentulous arches properly. For example, maxillary trays may need minor peripheral adjustments to seat evenly, while mandibular trays may require significant adjustments to fit reasonably.

Clinical Manipulation32

  1. ==Tray Fitting: Before mixing, seat the empty tray on the model/in the mouth to note the relationship between the tray handle and adjacent structures. This helps with accurate seating once the tray is loaded and visibility is lost.==
  2. ==Mixing:==
    • ==Accurate measurement is mandatory. Use the provided scoops and water measures (e.g., two scoops of powder to two measures of water).==
    • ==Sprinkle the powder into the water in a flexible bowl. Do not add water to the powder, as this leads to uneven wetting.==
    • Initially, stir with the tip of the spatula to wet the powder.
    • Vigorously spatulate the mixture against the side of the bowl until it is smooth and bubble-free.
  3. ==Loading and Seating:==
    • Load the mixture onto the tray, placing more material where the gap between the tray and tissues is greatest.
    • ==Do not wet the surface of the loaded material with extra water; while this smooths the surface, it also weakens it.==
    • Place the loaded tray in the mouth and perform muscle molding.
    • ==Do not move the tray while the material is setting.==
  4. ==Removal: Once set, remove the tray from the mouth with a snap motion to minimize distortion.==
  • Do not wet the surface of the material
  • No movement in mouth during setting
  • Snap out of mouth following setting
  • Rinse on removal from mouth
  • Disinfect by soaking
  • Pour cast as soon as possible

Assessment of Impressions3334

Question

After removal, rinse the impression under running water to remove debris. Then, check for the following:

  • Was the tray correctly oriented?

  • Are the borders fully and accurately recorded?

  • Are there any significant voids or areas where the tray has pushed through the material (pressure spots)?

  • Is there a uniform thickness of impression material?

  • Correct orientation of tray

  • Correct border extension

  • No voids or pressure spots

  • Uniform thickness of material

Storage of Impressions35

  • Set alginate can undergo imbibition or syneresis if left in a normal environment.

Irreversible Change

Both outcomes cause irreversible dimensional change and render the impression unusable.

  • After disinfection cover with damp gauze and place in Ziploc plastic bag.
  • Pour cast as soon as possible but no sooner than ten minutes following removal from mouth to allow elastic recovery.
  • Do not place in a refrigerator overnight.

Pouring Working Cast36

  1. ==Preparation: Upon receiving the impression, gently air-dry it to remove excess surface moisture.==
  2. ==Mixing Stone: Working casts are made with gypsum material (dental stone). Measure materials accurately and mix well (preferably mechanically under vacuum) to a creamy consistency.==
  3. ==Pouring:==
    • Vibrate the stone gently into the impression, filling it up to its borders.
    • Use the remaining stone to create a patty on the bench.
    • Leave the poured impression face up until the initial set of the stone.
    • Invert the impression onto the patty and trim away gross excess.
  4. ==Separation:==
    • Allow the cast to set fully.
    • Separate the alginate impression from the cast.
    • ==Do not delay separation, as the alginate will harden and shrink over time, which can damage the surface of the stone cast.==
  • Gently air-dry impression
  • Measure water & powder accurately
  • Mix stone to creamy consistency either manually or mechanically
    • Hand spatulation
    • Vacuum mixer
  • Vibrate stone into impression
  • Fill impression up to borders. Make stone patty with remainder
  • After initial set of stone invert impression onto patty

Working Cast

Question

If you have any questions, please contact me at the email address below.

Thank You

Any questions?

Contact me
Dr Ian Lander  ian.lander@uwa.edu.au

Contact me3738

Footnotes

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