440 likes | 460 Views
Relines and Rebases. Improving the Adaptation of Existing Dentures. Rebase. Replacing entire denture base Flasking, heat-cured acrylic Usually porcelain teeth. Reline. Resurfacing the tissue surface Jig used to maintain vertical dimension & occlusal contacts with cold-cure acrylic Or
E N D
Relines and Rebases Improving the Adaptation of Existing Dentures
Rebase • Replacing entire denture base • Flasking, heat-cured acrylic • Usually porcelain teeth
Reline • Resurfacing the tissue surface • Jig used to maintain vertical dimension & occlusal contacts with cold-cure acrylic Or • Reprocessing with heat cure
Indications Denture no longer fits residual ridge Retention, stability are lacking PLUS • Occlusion is acceptable • Vertical dimension is acceptable • Denture teeth/gingival contours acceptable
Contraindications Complaints of a loose denture DOES NOT, in itself, constitute evidence of a lack of fit and stability
Determine Cause of Looseness • Pivoting on bony structures • PIP • Occlusal interferences • Tactile, articulating paper, remount • Inadequate posterior palatal seal • Pull upward & outward on lingual of canines
Evaluate Cause of Looseness • Coronoid interferences • Side to side movements, PI{P • Flanges overextensions • Pull on the cheeks, lips, patient move tongue • Tight pterygomandibular raphe
Relines Will Only Solve Retention Problems Related to Denture Base Adaptation Retention problems must be diagnosed as to their cause
Types of Relines • Processed or chairside • Impression or functional technique • Hard acrylic or resilient • Permanent, temporary • Complete or partial dentures
Processed Acrylic Permanent Complete Denture Relines • Make impression for least stable denture first • Easier to stabilize the other denture • Reference for occlusion & vertical dimension
Impression Technique Difficult to reline without: • Encroaching on interocclusal space • Displacing the supporting tissues • Altering occlusal contacts USE CARE
Adjust Occlusion • Obtain stable occlusal contacts • Remount & adjustment may be required • Assess need for tissue conditioning
Remove Tissue Undercuts Allows impression to be removed from cast without breaking cast or denture
Border Mold • Relieve borders 2 mm short of vestibule • Border mold with compound • Maxillary posterior border at vibrating line (indelible stick)
Reduce Tissue Base • 1 mm if acceptable interocclusal distance • Use guide grooves • If interocclusal distance is excessive, relief may not be required • Perforate denture with #4 round bur
Impression Material Polyvinylsiloxane • Ease of use • Cleaning, removal from undercuts • Requires adhesive carried to the external surface of denture borders
Impression Procedure • Load carefully • Excessive material can reduce freeway space • Dry tissues
Impression Procedure • Seat denture anteriorly • Slowly rotate posterior into place • Ensure denture is not too far forward
Verifying Position • Patient closes lightly until first contact • If occlusal interdigitation is poor, physically move denture • Maintain position until set
Evaluate Impression • Trim impression to posterior border • Place / mark the posterior palatal seal • Check retention, extension, periphery • Remove excess (occlusal, facial etc.)
Deliver ASAP, usually next clinic Same day in practice, if possible
Impression Technique Advantages • Only two appointments needed • Tissues are captured at rest (less possibility of distortion) • Allows for greater extension of peripheries • Allows placement of functional posterior palatal seal
Impression Technique Disadvantages • Possible alteration in VDO, occlusion, facial support • No chance to test retention and comfort under function
Functional Relines (Lynal, Visco-gel) • Similar procedure • Minor variations
Functional Relines • Cannot extend borders greater than 4 mm • Distorts too easily • Grossly under extended, use impression technique
Functional Relines • Material requires greater thickness for accuracy • Usually need to reduce denture to allow for thickness
Variation in Accuracy of Materials (Visco-gel> Coe-Comfort)
Lynal • 10 ml powder : 2 ml liquid, mix 30 sec • If borders short or too thin, add more powder for increased viscosity • Thicker consistency can be formed into a 3 - 4 mm rope and placed around borders
Lynal • For tissue base, mix as per instructions • Place intraorally • Remove excess with cotton swab prior to set
Set time: 8-10 minute • Lightly border mold • During setting, allow patient to: • Talk • Swallow • Lightly occlude
Remove Excess • Reduce material on flanges with HOT scalpel or knife • Remove from teeth, oral surfaces • Patient wears reline home
Patient Returns in 24-48 Hours • A cast is poured within 2 hours • Otherwise, accuracy compromised
Functional Impression Advantages • Functionally molds peripheries • Ability to assess patient comfort and retention prior to reline proper
Functional Impression Disadvantages • Variability of materials, handling characteristics • Resiliency masks overextensions which can subsequently irritate, when converted to acrylic resin
Functional ImpressionDisadvantages • Dimensional stability variable • Patient care • Pouring of casts • Can' t significantly increase borders • Do not use simultaneously as a tissue conditioner
Partial Denture Relines • Similar procedures • Ensure rests, direct and indirect retainers are fully seated • Seat with pressure over the rests, NOT the distal extension bases
Partial Denture Relines • Allow no impression material under rests or guiding planes • If so, remake impression
Partial Denture Clinical Remount • If required, a new cast must be made • Make an alginate impression with the RPD in place
Partial Denture Clinical Remount • Block out undercuts on the framework while RPD is in the impression • Pour the model with the partial denture in place