Border Molding

Border Molding

Border Molding means shaping borders of impression tray

•  Functional or manual manipulation of tissues
  
•  Duplicates contour & size of vestibule
• Performed with

1. Thermoplastic modeling compound
2. Waxes
3. Impression materials

Tray Wax Spacer

• Remains in place during border molding procedures

Custom Tray

• Comfortable
• 2-3 mm from vestibule
• Dry periphery of tray (Compound will not stick to tray otherwise)

Heating Compound

• Use Bunsen Burner not Hanau Torch
• Warm until it starts to droop
• Do not overheat – if catches fire or boils, it will not mold properly

Compound Application

• Apply over periphery of tray, in a thickness just slightly narrower than the compound stick

Re-soften After Application

• Flame with a hand torch until all seams or sharp contours have disappeared
• Do not melt wax spacer inside tray

Preventing Slumping

• Hold the tray upside down so that compound droops toward the depth of the vestibule

Tempering Compound

• Temper in a water bath (135-140°F) for several seconds

1. Prevent burning
2. Hot water bath will keep compound soft for an extended period

Wax Spacer

 

 

• Keep out of hot water bath to prevent melting

1. Difficult to replace tray intraorally in the same position
2. Results in uneven border molding

Prepare Patient

• Patient seated, head against headrest, mouth open & relaxed
• If patient “opens wide”, commisures constrict, limiting access

Inserting the Custom Tray

• Place intraorally by rotating into place

1. Mold by pulling on the cheeks, lips
2. Have patient make functional movements

After Removal

• Chill in cold water
• Trim excess over wax spacer or external material that is thicker than 4-5 mm
  

 

• Clean debris from tray

Assessing Peripheral Role

• Proper thickness
• No overlap

Burnthrough

• Difficult to see (opaque)
• Relieve tray

After Trimming

• If border is sharp or has seams, re-flame, temper and readapt intraorally
• Repeat until periphery is completed

Border Molding

• Don’t reduce border molding prior to final impression if:

–      Modern low viscosity  materials are used

–      Sufficient relief (spacer + holes)

Maxilla – Seating the Tray

• Seat tray firmly in mid-palatal area during border molding procedures

Maxilla – Contouring

• Mold posterior buccal by pulling cheek down & forward with slight circular movement

Functional Movements

• Patient moves mandible side to side & opens wide

–      Molds the retrozygomal area

–      Allows for movement of coronoid process

–      Prevents impingement of pterygomandibular raphe

Maxilla – Labial Frenum

• Pull lip outward & downward

–      Do not pull to one side

• Labial frenum should be narrow
• Buccal frena usually broader, “V-shaped”
  

Maxilla – Posterior Border

• Add compound across the top of the tray (not at the edge)
• Terminates at vibrating line and hamular notches
• Mark with an indelible stick

–      Insert tray & check visually

Evaluating Border Molding

• Relatively symmetrical

Evaluating Maxillary Border Molding

• Retentive

Mandible

• More difficult
• Changing position of the floor of the mouth

Posterior Buccal Areas

• Pull cheek upward while holding tray in place
• Have patient suck cheeks inward while holding tray in place

Retromolar Pad  

• Should be covered (at least partially) to provide a seal and comfort to the patient
  

External Oblique Ridge

• Don’t extend past EOR
• Palpate cheek at angle of the mandible

–      Smooth transition between mandible & border – not palpable

Buccal Extension

• Look for fold in vestibule

Masseter Muscle

• Distal buccal extension
• Patient closes against force
• Activates the masseter, which will displace the compound

Mandibular Frenal Attachments

• Labial frenum is narrow

–      pull lip straight up,

–      not as exaggerated as maxilla

• Buccal frena broad & “V-shaped”

Posterior Lingual Areas

• Have patient touch their tongue to the corners of the mouth, to the palate and stick their tongue out of their mouth
• An “S” shaped lingual flange commonly results in posterior lingual area

Retromylohyoid Space

• Distolingual border can extend

–      Straight down from the retromolar pads

–      Anteriorly to varying degrees

–      Almost never angles posteriorly from retromolar pads

Posterior Lingual Areas

• Lower border at or slightly below mylohyoid ridge but not deeply into the undercut below the ridge,
• Minimizes, abrasion and discomfort
• Denture should not lift with normal tongue movements

Anterior Lingual

• Patient lifts tongue to palate, to corners of mouth and sticks tongue out
• Hold tray in place – denture should not lift with normal tongue movement

 

Tags: Border, Compound, Custom Tray, Labial Frenum, Mandible, Mandibular Frenal Attachments, Maxilla, Molding, Posterior Buccal Areas, Wax Spacer

Category: Articles, Prosthodontics, Prosthodontics, WIKI