Which areas should be examined when evaluating the quality of a maxillary alginate impression?

A quality preliminary impression should record all anatomic structures and landmarks that will be engaged by the finished dentures. This will permit the fabrication of properly designed and extended custom impressions trays which is the basis of obtaining a quality master impression. This program of instruction offers some valuable insights into the making of preliminary impressions for edentulous patients.

Complete Dentures – Preliminary Impressions — Course Transcript

• 1. 5. Preliminary Impressions John Beumer III, DDS, MS Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry UCLA School of Dentistry and Frank Lauciello DDS Ivoclar Vivadent This program of instruction is protected by copyright ©. No portion of this program of instruction may be reproduced, recorded or transferred by any means electronic, digital, photographic, mechanical etc., or by any information storage or retrieval system, without prior permission.
• 2. Preliminary Impressions
• 3. Preliminary Impressions Purpose: -for diagnosis and construction of custom impression trays . Requirements: -must capture all intraoral landmarks, retromolar pads, retromylohyoid space, hamular notches, etc. -will be slightly overextended but must essentially capture the 3-D contours of the vestibular borders of the limiting structures. ** An accurate preliminary cast that records all anatomic landmarks that should be covered by a denture permits fabrication of properly extended custom trays that will expedite border molding and facilitate a quality final impression.
• 4. Preliminary Impressions
• 5. Preliminary Impressions – Armamentarium -Alginate (reversable hydrocolloid) -Tray Adhesive -Edentulous metal stock trays -Plastic mixing bowl -Round edge spatula -Periphery wax -Water bath -Mouth mirror -2×2 gauge
• 6. Preliminary Impressions Select a stock tray Extend tray only where necessary with soft periphery wax Warm the periphery wax in a warm water bath, insert in patients mouth and mold the periphery wax to the intraoral contours Spray with tray adhesive Irreversible hydrocolloid impression The preliminary impression should have no major pressure spots or voids and it should capture all peripheral extensions Pour impressions in plaster with adequate bases including the central “tongue” area of the mandibular impression
• 7. Warm the periphery wax in a warm water bath, insert in patients mouth and mold the periphery wax to the intraoral contours. **Note: the pts existing denture can be used to help select an appropriate size tray. Preliminary Impressions
• 8. Preliminary Impressions Spray alginate adhesive onto tray
• 9. Practice tray insertion Mix the alginate with the round edge spatula . Mix in a vigorous manner using sweeping strokes against the walls of the mixing bowl. Mix to a creamy consistency . It is often recommended to use slightly less water than the directions specify to achieve a thicker mix. This is especially true for the maxillary impression to reduce the likelihood of gagging. Use the mirror handle to retract the lips as you rotate the tray into position . Message the lips and cheeks to border mold the peripheries . Tray ready to insert Alginate Mixing Tips:
• 10. Preliminary Impressions Mix alginate and load tray
• 11. Mandibular Alginate Impression Seat the tray and hold it firmly in position. Have the patient lift their tongue and displace it anteriorly .
• 12. Mandibular Alginate Impression Ideal impression should: Show no pressure spots Record the ridge, peripheries, retromolar pad, and the retromylohyoid fossa.
• 13. Insert tray Seat posterior portion Rotate the anterior portion into position Border mold the impression Completed impression Maxillary Alginate Impression
• 14. Dense mix of plaster Avoid entrapment of air bubbles Pour the impression with adequate plaster to create a base Note: The plaster should capture the contours of the labial-buccal border . Pouring the Preliminary Casts
• 15. The preliminary impression should have no major pressure spots or voids and it should capture all peripheral extensions. Pour impressions in plaster with adequate bases including the central “tongue” area of the mandibular impression. Completed Impressions
• 16. Alternate Technique- Accu-dent
• 17. Accu-Dent System 1 Irreversible hydrocolloid (hydrophilic) Two viscosities Non-slumping Premeasured sealed packaging Syringe delivery Temperature controlled Unique tray design Single entry impression system
• 18. Tray Selection
• 19. Post Dam Locate the physiologic posterior palatal seal area by having patient say “ah” Using an indelible stick, mark the palate just distal to where the palate vibrates. Palpate where the palatal tissues are displaceable (glandular area) and mark.
• 20. Mix the Syringe Gel using 70 °F water measured to the designated line on the vial. Back load the syringe Replace the plunger and express out any air. Set aside Syringe Gel
• 21. Mix the Tray Gel using 70 °F water measured to the designated line on the vial. The mix will appear dry at first but do not add additional water. Tray Gel
• 22. Accu-Dent Maxillary Impression Make sure a small amount of Tray Gel is pushed through the large holes in the tray for retention. Hold the tray under cold running water and smooth the surface with your fingers. The proper shape of the Tray Gel material is very important: most of the material should be in the front sloping to very little in the back. Loading the tray
• 23. Wipe dry the vestibules and palate with a 2×2 gauge. Express a line of the Syringe Gel into the vestibule from the hamular notch to the midline. Continue from opposite posterior to midline. Do not go all the way around in a single pass. Taking the Impression Accu-Dent Maxillary Impression
• 24. Taking the Impression Place a small amount of Syringe Gel in the anterior vault of the palate. Seat the tray from front to back. Stop seating the tray when a small amount of Syringe Gel appears in the distal edge of the tray. Accu-Dent Maxillary Impression
• 25. Pull straight down once on the filtrum at the vermilion border. Massage the cheeks very lightly downward with the fingers. Have the patient open wide Border Molding Accu-Dent Maxillary Impression
• 26. Tray Removal When set, break the seal at the distal buccal periphery and carefully remove the impression. Using the handle alone to remove the impression might dislodge the material. Disinfect according to OSHA guidelines and immediately pour the model Accu-Dent Maxillary Impression
• 27. Impression tray acts only as a method of delivering the impression material Accu-Dent Maxillary Impression
• 28. Accu-Dent Mandibular Impression
• 29. The lower Accu-Tray selection is accomplished in two steps, 1) tray type and 2) tray size Chose the tray that best suits either a normal ridge, or a highly resorbed ridge. Trays # 26-30 are designed with a moderate distal rise to accommodate the moderately resorbed ridge . Trays #20-24 are designed with a high distal rise to help accommodate the severely resorbed ridge . Accu-Dent Mandibular Impression Tray Type Tray Selection
• 30. Use the supplied calipers to measure the width of the residual ridge in the first molar region. This can be done on the existing denture, as shown, or in the patients mouth. Use this measurement to select the correct size lower tray. The caliper measurement should line up with the large holes in the first molar region of the lower tray. When in doubt use a smaller tray. Accu-Dent Mandibular Impression Tray Size Tray Selection
• 31. Mix the Syringe Gel using 70 °F water measured to the designated line on the vial. Back load the syringe Replace the plunger and express out any air. Set aside Syringe Gel
• 32. Mix the Tray Gel using 70 °F water measured to the designated line on the vial. The mix will appear dry at first but do not add additional water. Tray Gel
• 33. Mix the Tray Gel and place half on each side of the tray. Make sure that some of the tray material is pushed through the holes. This is the correct shape of the loaded tray. More material should be in the posterior of the tray. Give the Tray Gel a surface wash and rub smooth under cold running water with your fingers. Accu-Dent Mandibular Impression Loading the Tray
• 34. Express Syringe Gel from the retromolar pad forward to the midline. Repeat on the other side of the arch. It is not necessary to place Syringe Gel into the lingual vestibules. Place tray front to back until Syringe Gel appears in the posterior of the tray. Have the patient bring their tongue forward as you rotate the tray backward into position. When the Tray Gel rises up in the distal, Stop. Accu-Dent Mandibular Impression Taking the Impression
• 35. Completed lower impression Accu-Dent Mandibular Impression

This course has been awarded 5 hours of continuing education credit by the Iowa Dental Board.

General Instructions

According to the Board rule, training programs MUST consist of all of the following:  1. An initial assessment to determine the base entry level of all participants in the program. At a minimum, participants must be currently certified by the Dental Assisting National Board or must have one year of clinical dental assisting experience;      2. A didactic component;      3. A laboratory component, if necessary;      4. A clinical component, which may be obtained under the personal supervision of the participant’s supervising dentist while the participant is concurrently enrolled in the training program; and

     5. A post-course competency assessment at the conclusion of the training program.

Conduct an initial assessment to determine base entry level of all participants in the program.

Reference Materials

Required Reading:
Phinney & Halstead, Dental Assisting, A Comprehensive Approach, published by Delmar (Thompson), ISBN - 4018-3480-9, p. 607-617.

Suggested references to supplement didactic component: Miller, Michael, DDS; Reality, The Information Source for Esthetic Dentistry, The Techniques, Volume 1, p. 30-40.

Phinney, Donna J., Halstead, Judy H.: Delmar’s Handbook of Assisting, p. 234-236.

Objectives

    1. Identify the uses of impression materials for final impressions (i.e. alginate, polyether, rubber base, polyvinyl syloxane, reversible hydrocolloid, irreversible hydrocolloid, etc.)      2. Indicate common anomalies to examine for before taking an impression.      3. Indicate the rules to follow when selecting a proper tray size for the mandibular/maxillary arch.      4. List the purposes and disadvantages of wax-trimmed trays.      5. Select the proper standing position while taking a mandibular/maxillary impression.      6. Select probable results when the tray is seated too far anteriorly/posteriorly.      7. Indicate instructions given to the patient while taking a mandibular/maxillary impression.      8. Indicate how the setting time of impression material can be altered.      9. List three structures which can be pre-coated with alginate before an impression is taken.      10. Indicate the rules to follow when working with a patient who has the tendency to gag.      11. Select the anatomical structures that should be included in a mandibular/maxillary impression.      12. Indicate the causes of the following impression defects:        a. drags        b. bubbles        c. folds        d. indefinite developmental grooves        e. voids      13. Indicate the proper way to remove an impression.      14. Indicate the uses for bite registrations.

     15. List the materials that can be used to take a bite registration.

Didactic

I. Definitions  A. Impression - negative likeness of the teeth & supporting structures

 B. Cast - positive likeness (also called model)

II. Purposes and Uses of Study Casts  A. Treatment planning & case presentations  B. Custom tray fabrications  C. Opposing casts for crown and bridge work

 D. Orthodontic study models

III. Preparation of Patient  A. Explain procedure to relieve any tension  B. Position patient upright  C. Examine oral cavity    1. Removable appliance    2. Height of the palate    3. Any undercuts    4. Malpositioned teeth    5. Mandibular tori      a. adaptation of the tray may be necessary to prevent discomfort    6. If there is excessive debris and plaque, patient should have teeth cleaned or have patient brush teeth before taking the impressions  D. Request patient to use mouth rinse    1. Removes food and debris    2. Helps prevent air bubbles    3. Cuts the viscosity of the saliva

   4. Helps prevent gagging on maxillary impressions

IV. Preparation of Impression Trays  A. Trays should be tried in before impressions are taken for proper size  B. Width: there should be 1/8 to 1/4 of an inch space between the tray and the facial and lingual surfaces to provide strength and rigidity to the impression    1. The posterior teeth should be within the confines of the tray      a. If the buccal aspects of maxillary posterior teeth perforate into the impression material on both sides of the tray, the tray is too small

 C. Length: must cover the retro molar pad on mandibular arch and tuberosity on maxillary arch.

V. Wax Trimming (Beading, Utility or Periphery Wax)  A. Purposes    1. Protect tissue from injury and provide patient comfort    2. To extend the length    3. To add to the palate on a patient with a high palatal vault    4. Extends border to aid in obtaining impression of muscle attachments  B. Tray must be dry; adapt soft wax to tray  C. Try the waxed trimmed tray in the mouth again, before taking the impression  D. The wax must be covered with impression material

 E. Wax trimming increases the possibility for trapping voids

VI. Impression Material  A. Impression material is mixed according to manufactures directions.  B. To accelerate the setting use warm water, to retard use cooler water.  C. Strength and quality of the finished impression depends on:    1. Water powder ratio    2. Spatulation    3. Holding impression in position for optimum time    4. Correct tray selection  D. Filling the tray    1. Fill the tray from one end to another being careful not to trap air bubbles    2. Adapt material to tray; press slightly    3. Do not overload      a. Gag your patient      b. May cause tissue displacement

   4. May wet finger and pass lightly over impression materials surface and make slight indent where teeth will insert

VII. Procedure for Taking Mandibular Impression  A. Mandibular is obtained first to familiarize the patient & gagging is less likely  B. Precoat impression material on potential areas of air entrapment    1. Occlusal, incisal, and/or interproximal    2. Distal surface of teeth adjacent to edentulous areas    3. Cervical areas of erosion/abrasion    4. Vestibule around the frenums and muscle attachments  C. Right handed operates stands at 7:30 - 8 position, Left handed operates stand 4:30 - 5:00 position.    1. Grasp handle of tray with tray facing down    2. Rotate tray in mouth using opposite hand to retract opposite corner of the mouth    3. Center over teeth-1/4 in anterior to labial surface of most anterior incisor  D. Instruct patient to raise their tongue while tray is lowered  E. While seating the tray downward instruct patient to extend their tongue & then relax it  F. Muscle trim by pulling (retracting) lips and cheek forward    1. Muscle trimming - manipulating the cheeks & lips to conform the impression material to shape of vestibule  G. Apply equal pressure over premolar area; thumbs can be used to support the mandible  H. The occlusal plane of lower arch should be parallel to the floor when taking mandibular impression. Hold tray in position until set.  I. Removal of impression    1. Hold tray handle with thumb & finger    2. Retract cheek and lip and release edge of impression by lifting up on posterior buccal vestibule    3. Remove impression with a snap to prevent distortion  J. Rinse & disinfect & leave in plastic bag for 10 min.  K. Evaluate impression

 L. Patient may rinse before maxillary impression is taken

VIII. Procedure for Taking Maxillary Impression  A. Precoat impression material as stated in mandibular procedure  B. Stand at 11:00-12:00 for Right handed, 12:00-1:00 for Left handed  C. To avoid excess impression material in posterior area load majority of material in anterior portion of tray. A small amount of impression material may be removed from the palate area also.  D. Grasp handle with tray facing upward and with left finger, retract left cheek  E. Retract right cheek with tray & rotate in the mouth  F. Center tray handle with nose  G. Seat posterior first then anterior which forces material forward    1. Instruct patient to breath through nose    2. Patient’s head may be tilted forward  H. Retract lip as inserting the anterior  I. Muscle trim by rolling the cheeks and request patient to form a tight “O” with lips to mold the impression material  J. Maintain equal pressure on each side of the tray  K. Retract lip and cheek and break posterior seal and remove with snap  L. Rinse & disinfect

IX. Evaluation of Impressions by dentist

   3. Improper mixing

X. Impressions Should Include Surrounding Tissue Structures  A. Maxillary impression should include    1. Labial Frenum    2. Buccal Muscle attachments (Buccal Frenum)    3. Mucco-buccal fold (vestibule)      a. Muscle trim & pull lips forward while seating tray    4. Tuberosity    5. Palatal tissue (rugae)    6. Hamular notch & process    7. Palentine Fovea      a. A depression between the hard & soft palate  B. Mandibular impression should include:    1. Labial Frenum    2. Lingual Frenum    3. Lingual Frange      a. Have patient stick tongue out to muscle trim lingual frange    4. Mucco-buccal fold (Vestibule)    5. Buccal muscle attachments    6. Retro-molar pad

     a. If less than 3 mm of retro molar pad was visible, the tray was seated too far anteriorly

XI. The Interocclusal Record (Bite Registrations)  A. Purpose    1. To record the alignment of the teeth    2. To relate the mandibular to the maxillary cast correctly    3. Place between the cast, during trimming & storage    4. Special indications when wax bite is generally needed       a. Open bite, end-to-end, edentulous areas  B. Procedure for Wax-type Registration    1. Have patient practice opening & closing on back teeth to assure correct position can be obtained    2. Have patient rinse with cold water (optional)    3. Shape a double layer of soft baseplate wax in form of a arch or use shaped bite wax    4. Warm wax over bunsen burner or warm water    5. Place wax over occlusal surfaces    6. Instruct patient to close on back teeth    7. May press wax on facial to shape it accurately to the arch    8. Remove & chill in cold water  C. Procedure for Paste-type Registration    1. Extrude base & catalyst on a mixing pad or use the gun type dispenser    2. Mix to a homogeneous consistency with no streaks    3. The bite registration frame with a gauze insert is loaded on both sides with the impression paste    4. Tray is placed in mouth & patient is instructed to close on back teeth during the setting

   5. Bite registration is removed

Clinical/Lab

Go back to III –XI and perform each of these procedures in a clinical setting and a lab, if appropriate. Please note that all clinical training must be done under the personal supervision of a dentist, which means that the dentist must be physically present in the treatment room.

Post-course competency assessment must be completed at the conclusion of the training program. This means you must develop a test to ensure participants have learned the necessary material and can perform these skills to written and clinical competency. Keep a copy of your competency assessment and the participants results as part of the documentation of training.

Document successful completion of this training on the Documentation of Training Form and maintain this proof in the dental office of practice.