Log in Register

Login to your account

Username *
Password *
Remember Me

Create an account

Fields marked with an asterisk (*) are required.
Name *
Username *
Password *
Verify password *
Email *
Verify email *
Captcha *

Captcha Image Reload image challenge



Authors: Dr. Siddharth Sisodia, Dr. Deeksha Agrawal

Abstract

The importance of an accurately fitting fixed prosthesis or a removable prosthesis is essential for the success of the restoration. Ill-fitting prosthesis may cause mechanical failures of the prosthesis, implant systems, or biologic complications of the surrounding tissue. There are several causes related to improper seating of the prosthesis. Some of which can be corrected and the others need to be repeated. Hence the clinician must carefully evaluate the adaptation of the prosthesis using the clinical techniques and combination of the available materials and evaluation methods to optimize the fit of prosthesis. This article reviews the various clinical methods that have been suggested for evaluating the fit of the fixed and removable prosthesis.

INTRODUCTION

The importance of an accurately fitting fixed prosthesis or a removable prosthesis is essential for the success of the restoration. Ill-fitting prosthesis may cause mechanical failures of the prosthesis, implant systems, or biologic complications of the surrounding tissue. There are several causes related to improper seating of the prosthesis. Some of which can be corrected and the others need to be repeated. Hence the clinician must carefully evaluate the adaptation of the prosthesis using the clinical techniques and combination of the available materials and evaluation methods to optimize the fit of prosthesis.

DISCLOSING MATERIALS

These are the materials used to fit/adjust a prosthesis (Fixed partial denture,Removable partial denture, Implant supported prosthesis or complete denture framework) by identifying areas of interference and binding or overextension when seated intraorally or extraorally on cast.

CLASSIFICATION
  1. Based on the type of prosthesis-RPD ,FPD,Implant,complete denture
  2. Based on the consistency- solid,liquid,gas,spray,paste,powder form
VARIOUS DISCLOSING MEDIUM AVAILABLE ARE-

1. Disclosing wax- A creamy wax used to determine the fit of full and partial dentures,implant frameworks in relation to supporting tissues.

  • Fill the restoration with disclosing wax, and heat it over the flame until wax flows, so that it flows into the pores of the metal and adheres to the internal surface of the restoration. Allow the restoration to cool before try in. Then place the restoration on the tooth and seat it. Test the interproximal contact with floss, and adjust if in excess. Repeat the process until the interproximal contacts are perfected.
  • Any area which keeps the restoration from seating will appear as a bright shiny spot. This process should be repeated until the wax on the inner occlusal surface becomes very thin.
  • Warm the restoration and remove the wax before final cementation.
Advantage
  • As the wax is translucent and 3D in nature ,it provides clear visual evidence regarding framework adaptation . In thin films,disclosing wax takes on the grayish appearance of the rpd framework while in thicker films ,the wax appears white.
  • Therefore ,disclosing wax will indicate not only whether a framework is well adapted to the associated teeth ,but also areas of binding and areas that display substantial misfit.
  • Disclosing wax is added to all areas of the framework that contact the teeth and labial arm(swing lock prosthesis)
  • Disclosing wax can be added to denture base flanges to help identify areas of overextension
  • Can be used for implant framework fit.
Disadvantage-
  • Disclosing wax can not be used for evaluation of fit of denture bases because it is resistant to displacement by soft tissues.
Disclosing wax applied on the intaglio surface of framework
 

2. Halothane and rouge : an alternative to chloroform and rouge

  • Halothane (bromochlorotriflouroethane) serves as an excellent alternative to chloroform and used in restorative dentistry as a disclosing medium to improve the internal fit of crowns,dowels and cores ,FPD framework,RPD framework.
  • It is a highly volatile anesthetic inhalation solution that is non explosive ,noninflammable and used for the induction and maintenance of general anesthesia.
  • It is non-toxic,non-carcinogenic,non-mutagenic .
  • No teratogenic effects in humans.
Advantage-
  • It rapidly dissolves rouge and produces uniform homogeneous solution form as a thin consistency.
  • Extremely volatile so the mixture will dry quickly.
  • High spots and internal discrepancies are easily detected with this mixture and because of its thin consistency ,can be applied again to detect further discrepancies and it won’t result in excessive film thickness.
  • Spray-type disclosing media are often used during fitting procedures.
Disadvantage-
  • Often messy and difficult to control in the presence of moisture so it should not be used for intraoral fitting procedures.
  • Accidental exposure to large doses can be lethal.


3. Polyvinyl Siloxane Impression Material, Low Viscosity type 1

  • This material can be used to reline the denture to identify areas of overextension.
  • After the impression material sets, evaluate it to check the fit of the denture base to the basal tissues and peel it out of the denture.
Advantage
  • Can be used in fixed or removable partial frameworks fit check.Can be used in patients with embrasure undercuts
  • They are easy to use and easy to remove from the framework,
  • provide a three-dimensional perspective, and have minimal thickness.
  • Optimum flowability
  • Excellent detail record
  • Not affected by saliva
  • Leave a residue free clean surface.
Disadvantage-

They are expensive, require mixing, and need time for the material to Set



4. Occlude disclosing medium-

  • Gas form disclosing medium to identify areas of interference in RPD or FPD framework.
Advantages-
  • It marks areas of interference well(thin and accurate) and is easy to clean off.
Disadvantage-
  • It is expensive.
  • There is potential for applying too thick layer of material.
  • It is difficult to work in a wet environment.

5. Pressure indicating paste –

  • pressure indicators are used as disclosing medium to identify problems related to impingement, extension, and/or width of prostheses
  • It can also be used in complete dentures,immediate dentures after surgery,,cast partial dentures,inlay fit,implant framework.,fixed prosthesis.
  • There are variety of pastes that may be used in denture base evaluation.
  • These consist principally of equal volumes of zinc oxide powder combined with medium consistency vegetable fat,which are blended together.
  • Application of thin layer on the intaglio surface of denture base with a stiff brush
Advantages-
  • Inexpensive and convenient
  • Can be used on soft tissue unlike disclosing wax
  • Identify exact location,size ,shape and thickness of denture sore spots
  • It is accurate as it doesn’t have bulk that disorients the denture .
  • It is fast and ready to use .
  • No need of heating and no need to wait to soften in mouth & it remains constant regardless of temperature.
Disadvantage-
  • Expertization is required to differentiate the marks to avoid unnecessary adjustments
  • Messy and time consuming to clean from deeply fissured denture base.


6. Color transfer applicator

  • These disposable applicators are used for making color transfers from irritated areas under complete or partial dentures
Advantage-
  • Easy to use and dispensing feature
  • Accurate
  • Less time consuming
  • Minimum of smearing is required
Disadvantage-
  • Rely on sore spots being easily visible and do not provide guidance on the extent of the necessary adjustment
 

7. Fast Setting Irreversible Hydrocolloid Material (Alginate)

  • These materials can also be used as disclosing medium specially for complete dentures.
  • Mix a small amount of impression material. Reline the denture in the area in question.
  • Seat the prosthesis in the mouth and have the patient close into normal occlusion. Allow the material to set and then remove the denture carefully without tearing the alginate. The area needing adjustment usually is easy to visualize. The denture is relieved, and the alginate can be simply peeled away. The process is repeated until no high spot is seen
Advantage-
  • Easy to use
Disadvantage-
  • Less accurate
 

8. Temporary cement

  • A liner or wash of temporary cement is an extremely convenient material to use as a disclosing agent.
  • The white color contrasts well with the casting color to make minor discrepancies visible and the material is opaque so that only actual discrepancies bleed through for adjusting.
  • Its film thickness is similar to the luting agents such as zinc phosphate cement .
  • Mostly used with fixed partial dentures.
Advantage-
  • Easy to use .
  • Easy to remove from inside of the casting.
Disadvantage-
  • Mixing is required and it should not set before seating intraorally

9. Unwaxed floss-
  • Used to check any interference in interproximal contact areas.
  • Used in RPD ,FPD ,Implant framework

10. Shim stock, Polyester film strips


SUMMARY

The success of prosthesis depends on how well it fits without causing injury to the remaining teeth and soft tissues.Improving the clinical techniques and combination of the available materials and evaluation methods can optimize the fit of prosthesis.Use of an indicating medium is one of several strategies that clinicians can employ for improving diagnosis and correction of denture-related problems. Denture adjustments are more accurate and effective when made using an indicating medium. The aerosol spray media is judged to be the most acceptable of those tested because they are easy to use and afford minimal waste; they also adhere well to removable partial denture metals and can be easily removed, they are not washed away by excess saliva.Choose the disclosing medium according to the type of prostheses to get the accurate results.

References-
  1. Rodney phoenix et al ;An effective technique for denture border evaluation; Journal of prosthodontics;Volume 6, Issue 3 (215–217);September 1997.
  2. Mallika S. Shetty;Techniques for evaluating the fit of removable and fixed Prosthesis ;ISRN Dentistry,2011 .
  3. D. B. Evans, “Halothane and rouge: an alternative to chloroform and rouge as a disclosing medium,” The Journal of Prosthetic Dentistry, vol. 74, no. 2, pp. 209–211, 1995.
  4. G. R. Troendle and K. B. Troendle, “Polyvinyl siloxane as a disclosing medium,” The Journal of Prosthetic Dentistry,Journal of prosthetic dentistry vol. 68, no. 6( 983–984), August 1992.
  5. J.E Noonan et al;The use of temporary cement as a disclosing medium to improve the seating of gold castings; Volume 60, Issue 5,Page 644; Nov 1988.
  6. Improved Marginal Seating of Cast Restorations Using A Silicone Disclosing Medium;Int journal of prosthodontics;Volume 4,Issue 4 (323-326);July1991

Add comment


Security code
Refresh