Dental Problems

Designing For Proximal Lesions

DenturesPlaque accumulates readily immediately below the contact area between any two teeth, anterior as well as posteriors. Proximal lesions can be formed due to bacterial activity or due to other factors. Thus, designing for proximal lesions is one of the treatment which is discusses briefly in this article. Let us examine them.

Designing for proximal lesions

  • In the absence of good plaque control and regulation of refined carbohydrate intake the pH interproximally will fluctuate frequently to levels well below pH 5.5 and regular attacks of demineralization may occur.
  • There will be no occlusal load on these lesions so plaque will not be forced into the developing cavitation as happens on the occlusal surface, so progress through tooth structure may be quite slow.
  • In the absence of cavitation there is always a chance that the lesion can be healed through remineralisation so the current recommendation is to keep an early lesion under careful observation before proceeding to surgical intervention.
  • On the other hand, the anatomy of the deciduous tooth suggests that intervention should be undertaken early rather than later because of the risk of pulpal involvement.
  • At the same time, there are considerable risks involved in cutting a cavity in certain areas, particularly in the proximal surfaces of deciduous molars in which the mesiobuccal pulp horn is often very close to the surface.
  • So the risk or benefit ratio will need to be assessed in many cases before a treatment plan is finally formulated.

There are three alternatives available for the preparation of cavity which are discussed below.

1. Tunnel cavity:

  • If the cavity is very small and more than 2.5 mm from the crest of the marginal ridge, it is possible to develop a so called tunnel type cavity.
  • This involves approaching the dentin lesion from the occlusal fossa just medial to the marginal ridge using a small tapered diamond cylinder at intermediate high speed under air water spray.
  • Aim diagonally towards the lesion and develop a small access cavity.
  • Having located the lesion upright the same bur and move it cautiously into the marginal ridge and lean it to the buccal and then to the lingual to develop a triangular entry tunnel into the carious dentin.
  • Once the lesion has been identified use a small round bur at low speed to carefully clean the gingival floor, the buccal wall and the lingual wall but leave the pulpal wall untouched.
  • The inner wall of the proximal enamel can now be explored carefully for signs of cavitation.
  • If the wall is intact there is no need to break through to the external surface because the enamel will most certainly heal in the short term.
  • In the presence of cavitation lightly debride the walls of the enamel cavity with a very small chisel to clean fragile enamel prisms.
  • The cavity is now ready for restoration and the preferred material is a glass ionomer.
  • It can be syringed and tamped into place and on the assumption that there are clean walls around the full circumference of the cavity, there will be a complete seal and the potential for remineralization of the pulpal wall if required.
  • Internal preparation (partial or blind tunnel)

    : If the approximal enamel in relation to the lesion is demineralized but not cavitated, it is not necessary to break through the enamel because it is likely that, with good preventive follow up, it can be remineralized.

2. Slot cavity or Minibox restoration:

  • The next alternative could be the preferred design for the small proximal lesion in all deciduous teeth.
  • It has been loosely titled slot or box cavity and involves approaching the lesion through the crest or outer surface of the marginal ridge.
  • Entry should be very conservative in the beginning and it should be extended only as dictated by the extent of the lesion.
  • Confine the cavity to the extent of the caries only and retain as much tooth structure as possible.
  • The restorative material of choice is the glass ionomer.
  • There will be a greater exposure to occlusal load with this design and there will be a greater need to consider the advantages of lamination with composite resin.

3. Proximal approach:

  • The third potential approach to the proximal lesion becomes possible only if the adjacent tooth is missing or else has a fairly extensive cavity already prepared in it.
  • This will allow a direct access to the lesion and can lead to a very conservative cavity with no involvement of the marginal ridge at all. Remove only the completely broken down enamel sufficient to allow access to the dentin, use a small round bur to clean the walls but leave the axial walls alone.
  • Use a radioopaque restorative material because it will need to be visible to another operator who may other wise mistake it for a carious lesion.
  • The advantages of above preparations in comparison with conventional Class II preparation are listed below:
    • It is conservative, maintains marginal ridge which contributes to conserve the tooth strength.
    • Prevents the risk for iatrogenic damage to the adjacent approximal surface is minimized.
    • A normal contact area is maintained.

Smart materials:

  • A new generation of materials is being released for an ideal restorative material.
  • These materials may not be commercially available, but may have the potential to replace the currently used ones.
  • Thus, these materials have been probably termed as ‘smart’as they are consistent with the newer generation of materials which support the remaining tooth structure to the extent that cavity preparation can be done in the most conservative way.
  • Some of these materials are ‘biomimetic’in nature, wherein there may be properties that ‘mimic’natural tooth substance such as enamel or dentine better and one step further in the concept of tissue regeneration, where in the tissues can be regrown in the oral cavity.
  • Along these lines BRAX -I gene has been isolated, which is thought to be responsible for the control on enamel growth.

The above article discusses briefly about the designing for proximal lesions with various alternative approaches.

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