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Relining and rebasing in cd


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Relining and rebasing in cd

  1. 1. Guided ByDr. Sumathi Zunzani Submitted ByIrfan BDS – Final year
  2. 2. Table of Contents  Introduction  Treatment Rationale  Definitions :- Relining & Rebasing  Objectives  Common Indications For Relining &        Rebasing Contraindications General Complaints General Consideration Prior To Reining Or Rebasing Materials Used Pretreatment Procedures :Tissue Preparation Denture Preparation Techniques :Clinical Procedures Laboratory Procedures Chair Side Technique Conclusion
  3. 3. Introduction  A number of changes can occur in tissues that support complete denture., these changes can entirely be avoided, and the need to “servicing” complete denture to keep pace with the chanaging foundations becomes mandatory. The clinical efforts that aim at prolonging the useful life of complete dentures involve a Reline or Rebase procedure.
  4. 4. Treatment Rationale  As the denture foundations change, the impression surfaces of dentures cease to fit the tissue properly . The procedure used is a reining one, & the dentist achieves this by adding new denture base materials to the existing denture base , thereby refitting the denture. Rebasing of dentures is undertaken when the dentures need to be refitted & simultaneously reoriented as well. This is done so as to compensate for vertical & horizontal changes in both
  5. 5. Relining The procedure used to resurface the tissue surface of a denture with new base material to make the denture fit more accurately. -- GPT Or The process of adding base material to the tissue surface of the denture in a quantity sufficient to fill the space, which exist between the original denture contour and the altered tissue contour. – SHARRY Rebasing Rebasing is a process of replacing all the base material of a denture. Only the original teeth and their arrangement remain. Or It consists of replacing all of the
  6. 6. Objectives The main objectives of relining or rebasing are to:  Re-establish the correct relation of the denture to basal tissue.  Restore stability and retention  Restore lost occlusal and maxillo- mandibular relationship.
  7. 7. Common Indications for Relining and Rebasing  Imperfection in the denture base  Defects in the impression surface of the denture due to  Improper handling of the tissues during impression making.  Processing defects  Porosities, shrinkage/contraction, gaseous, granular.  Crazing of the material  Alveolar resorption  Continued resorption of the residual alveolar ridge under the complete denture.  Decreased occlusal vertical dimension  Due to faulty techniques  Immediate dentures  Regular periodic relines are required
  8. 8. Common Indications for Relining and Rebasing  Socioeconomic constraints  New denture costs are unaffordable  Physical/ mental state of the patient.  Chronically ill patients  Geriatrics  Mentally compromised individuals Contraindications  Excessive resorption of the alveolar     ridge Highly inflamed/ abused soft tissues Poor, unacceptable esthetics TMJ problems Unsatisfactory jaw relation  Horizontal, vertical and orientation relations  Severe osseous undercuts which require surgical correction  Severe speech problems
  9. 9. General Complaints After a period of successful denture wear the patient complains of  Looseness  Ill-fitting dentures with loss of stability and retention.  General soreness and inflammation  Chewing inefficiency over a period of time  Aesthetic problems. General Consideration Prior to Relining Or Rebasing Satisfactory VDO CO should coincide with CR. Satisfactory esthetics Healthy oral tissues Adequate denture base extensions Adequate load distribution on the basal seat  Satisfactory speech  Suitable/healthy soft tissues with out      
  10. 10. Materials PMMA 1. • • Heat cured acrylic resin Cold cured acrylic resin Modifications of PMMA 2. • Butyl meth acrylate Soft liners/ tissue conditioners 3. • Plasticized acrylic resin • • • • Chemically activated…. short term denture liners Heat activated…. long term denture liners Vinyl resins Silicone materials   Chemically activated Heat activated
  11. 11. Pretreatment Procedures The clinical procedures of relining and rebasing includes both tissue and denture preparations 1.Tissue Preparation: A). Tissue Rest: 1. Instruct the patient to leave the old dentures out of the mouth at least 8 hours preferably at night. 2. The dentures should be left out of the mouth at least two to three days before making the final impression. 3. Massage of the soft tissues two or three times a day to stimulate the blood supply and aid recovery. B) Use of Tissue Conditioner 1. Extensive tissue abuse 2. Pt. cannot leave the dentures out for tissue recovery. 3. Transmission of masticatory forces to the supporting mucosa are equalized by eliminating isolated pressure spots typical of a loose, ill fitting denture.
  12. 12. The material is renewed periodically every 3 to 7 days. 5. When the tissues had returned to a clinically discernible healthy state, the patient is scheduled for making the impression. C). Surgical management: Excessive hypertrophic tissue should be surgically removed. The denture can be used as a surgical splint. 4. Denture Preparation 1. 2. 3. 4. 5. Balanced occlusion to ensure that uneven contact does not bring about a bodily shift or tilt of the denture when the patient is asked to close together. Reduction of sharp and overextended borders. Pressure areas in the tissue surface of the dentures should be relieved. Borders should be shortened to allow space for new impression material. All undercuts should be removed.
  13. 13. Techniques  Clinical procedures  Static Methods:  Open Mouth Technique  Closed Mouth Technique  Functional Method  Laboratory procedures  Articulator Method  Jig Method  Flask Method  Chair side technique
  14. 14. Clinical procedures  Static Method Open Mouth Technique: Given by Carl O. Boucher.  Reining & rebasing of both upper & lower dentures at the same time.  Dentures are used as special trays for making secondary impression. ZnOE is the material of choice , then the impressions are made.  After impression a new Centric Relation is recorded. Advantages:  Selective Trimming helps to make selective pressure impression.  Interoccusal record is reliabe b/c jaw relation is under consideration. Disadvantages:  Difficult procedure b/c more clinical and lab work is involved.
  15. 15.  Closed Mouth Technique:- Relining or rebasing can not be done simultaneously for maxillary & mandibular dentures. There are 4 techniques:i. Technique A ii. Technique B iii. Technique C iv. Technique D  Technique A:Centric relation (inter-occlusal record) is recorded using wax or compound 1.5 to 2 mm relief should be given to large undercuts. Borders are reduced by 1 to 2 mm excepted the posterior region. The centre portion of the palate in the denture can be removed for visibility in positioning the maxillary denture during impression making.
  16. 16. Border moulding is done & impression is made from ZnOE impression material . Patient is asked to close lightly to interocclusal record & if the palatal portion is cut, quick setting plaster should be used to make impression. Advantages Palatal opening will allow better seating of denture & alleviate the increase in vertical dimension.  Pre-made interocclusal record helps to position the denture during impression making.  It also helps in orienting dentures in an articulator.  2 step procedure – Reduces possibility of moving the maxillary denture forward during final impression. Disadvantage Simultaneously maxillary & mandibular dentures are not relined or rebased.  o o o Technique B :Existing Centric relation is used. Dentures are prepared as Technique A. Border moulding is done using low fusing Impression Compound.
  17. 17. Impression is made in 2 stepso Ist Step- Impression of all areas except labial flange & alveolar crest in b/w canines is recorded. o IInd Step- Labial flange & alveolar crest in b/w canines is recorded. Advantage – It will reduce the extreme forward movement of the denture. Disadvantage - Wax distort easily.  Technique C:o Existing centric relation is used. o Denture prepared as in Technique A. o Labial & palatal flanges are perforated to decrease the pressure inside dentures during the impression making. o Border moulding & impression making is
  18. 18.  Technique D:- o Existing centric relation is used. o Denture prepared as in Technique A. o o o o o o Borders & shortened & made flat. Large opening is made at mid palatal region. Adhesive tapes are attached over the buccal & labial surfaces of both debtures 2 mm above the denture borders. Dental plaster & ZnOE is used for impression. Plaster of paris used for palatal portion. After impression making, a deep groove is cut into labial & buccal surfaces of the dentures at the junction of impression material & adhesive tape, & filled with molten wax. Wax at the edge is used to record sulcus.
  19. 19. Procedure of Technique “D”
  20. 20.  Functional Method:- Given by Winkler.  Dentures are not required for laboratory procedures.  Fluid Resin (tissue conditioners) are used as impression material.  Tissue conditioners are usually soft liners with following characteristics :o Easy to use. o Excellent for refitting C.D. o Capable for retaining for man weeks. o Good in dimensional stability. o Good in bonding to resin denture base. Procedure Avoid night wear of the denture.  Occlusal errors should be corrected so Centric Occlusion coincides with Centric Relation.  Tissue surface is reduced to accommodate tissue conditioning material.  Tissue surface is dried & tissue conditioning material is placed. It should flow evenly as a thin layer to cover the entire impression surface of denture & its borders. .
  21. 21.  Now the denture is inserted & the patient’s mandible is guided to Centric Relation, in order to stabilize the denture & the material is allowed to set . Once the material is set impression is removed & excess material is trimmed. If poor recording of borders has been done b/c of un-supported area the border moulding is done with green stick compound.  After 3 to 5 days dentures are examined for depressed areas which should be relieved. The material should be renewed periodically (once in a week) till tissue healing is complete.  Then impression with ZnOE is taken over the tissue conditioner material & a cast is poured immediately. During the
  22. 22. Laboratory procedures  Articulator method: Impression is obtained.  Cast is poured.  Maxillary cast is mounted on articulator with face bow.  Mandibular denture is mounted using an inter-occlusal record, if occlusal discrepancy is present.  For relining the required amount of tissue surface of the existing denture is trimmed always using an acrylic bur. If rebasing is to be done, the denture base should be trimmed to just leave 2 mm of acrylic around the existing teeth.  After trimming the dentures are placed in the articulator & waxed up without altering the vertical height.
  23. 23.  Jig method:- Two types of jigs are there1. Hooper’s Duplicator – Having 3 pillars. 2. Jectron Jig – Having 2 pillars.
  24. 24.  Flask Method :- Procedure-
  25. 25. Chair Side Procedure The method makes use of acrylic that could be added to the denture & allowed to set in the mouth to produce instant relining/rebasing.  Disadvantages Material produces a chemical burn in oral mucosa.  Material is porous & develops a bad odour.  Poor color stability.  Material is not easy to remove if not placed correctly. Now-a-days Visible light cure resin is used.  Conclusion :Each of the method can produce satisfactorily result. Impression materials include both auto polymerizing resin & tissue conditioners. Success depends on both clinical & laboratory skills of the operators. Choice of treatment whether to perform relining or rebasing depends on the condition
  26. 26. Reference  Boucher's Prosthodontic Treatment for Edentulous Patients.  Essentials of Complete Denture Prosthodontics by Sheldon Winkler. 