Dental Problems

Clinical Steps for Dental Composite Resin

ToothDental composite resin is used for the restoration of the tooth. These treatment procedures are examined clinically. In this article, there is a brief discussion on the clinical steps for dental composite resin. Let us examine them.

Clinical steps for dental composite resin:

Etching and bonding:

  • An essential prerequisite for the micro-mechanical attachment is that the enamel must be etched with about 37 percent of orthophosphoric acid as to deminieralize the tooth enamel to about 20-30µm of depth and to render it porous.
  • A very low viscosity unfilled resin is then flowed over the surface and is allowed to soak within the porosities for 30 seconds before it is light activated. Composite resin is later built over the resin bond.

Prerequisites for etching:

  • Firstly, the tooth enamel at the cavity margin should be fully mineralized, which is based on a healthy dentin.
  • Tooth should not have any micro cracks. It is desirable to develop a long bevel at the cavo-surface margin reasonably as it the best union to be developed on the ends of tooth enamel rods rather than along the long sides so.
  • In juvenile enamel there is less mineral ad more organic collagen present and therefore the etch pattern is quite different.
  • There will be more water present because of the presence of dentin tubules and their direct access to the pulp and the amount of fluid flow will only be enhanced following acid etching because it will lead to opening and funneling of the tubules.
  • In deciduous tooth even a small cavity will be relatively close to the pulp and therefore there will be a greater density of tubules on the floor of the cavity and a relatively greater fluid flow.
  • The goal of a bonding agent of resin dentin is to attach composite resin to a healthy dentin and then to seal the dentin tubules for protection against bacteria and bacterial toxins.
  • This prevents post restoration sensitivity, loss of restoration and caries. Bonding to dentin requires the removal of all demineralized affected dentin and this is not always desirable, particularly in a deciduous tooth where there will be little enough dentin remaining above the pulp and an exposure is undesirable.
  • It is possible through the use of glass ionomer to remineralize some of the dentin and this is preferred method of sealing a cavity in a deciduous tooth.

Principles to follow for a successful resin-dentin bonding:

  • The dentin must be etched as to remove dentin tubule plugs and smear layer.
  • Etching should be sufficient to demineralize the surface layer of both inter and intratubular dentin leaving collagen fibres exposed and available for a mechanical interlock with the resin.
  • To remove all the remaining etchant the surface must be thoroughly washed.
  • The surface must not be flooded but should remain wet.
  • Application of hydrophilic primer containing either acetone or similar product to facilitate the penetration of adhesive resin over the exposed fibers of collagen.
  • Finally apply an adhesive resin and cure it before composite resin application.

Delivery and placement:

  • The chemical cure and the dual cure materials will be packaged as a paste or paste system or a powder or liquid system. Always follow the manufacturers’instructions in detail and stay within the time parameters so as not to go beyond the working time.
  • To ensure complete adaption to the cavity floor, it is desirable to apply freshly mixed material in disposable syringe and later tamp the material inside the cavity using the small plastic sponge.
  • The light activated materials will always be delivered in light proof carpules or syringes which have been loaded under vacuum. This means that they are free of porosity at the time of delivery.
  • Placement must be done with attention and care to detail with particular reference to the cure depth available with a curing light.
  • The efficiency of the light must be checked periodically to ensure that there is an adequate cure even in the lower layers.

Incremental build up:

  • It is very essential to undertake an incremental buildup of dental restoration for about 2.0 mm deeper.
  • Incremental placement means the placement of composite resin in small quantities into the cavity and later a light activating unit is directed in such a way that, while curing, the resin will shrink towards the tooth structure rather than away from it.
  • It is recommended that the increments be as small as possible and the light activator be applied from various positions during the composite resin build up.
  • However, the direction and position of the first application of the light is critical to the over-all success of the restoration.

Depth of cure:

  • A composite resin cure depth in a child patient’s oral environment is of quite significant.
  • Therefore, it is necessary to place the activator light within 1-2 mm on the surface of a newly placed tooth restoration otherwise there will be a limited cure depth.
  • Failure to light activation of the composite resin to the full depth of the restoration has important implications for the success and longevity of the restoration.

Factors while curing:

  • With an increase in depth there will be a decrease in the cure degree.
  • Increased time of light exposure will increase the cure depth.
  • The more heavily filled resin with larger particle size, the depth of cure is greater. Micro filled resins will cure about 2-3 mm of depth only while the hybrid resins might cure to about 4-5 mm of depth.
  • Lighter the material shade, greater the cure depth and greater the translucency, cure is deeper.
  • Light activator units vary in their light outputs overtime as well as with power fluctuations.
  • The efficiency of each unit should be checked frequently.
  • The light source tip must be placed as closely as possible to tooth restoration and must never be more than 4 mm away.
  • The depth of cure should be measures from the face of the activator light.
  • Curing through tooth structure will reduce the depth of cure to the same extent as it curing through a composite resin of similar opacity.

The above article discusses briefly about the clinical steps for dental composite resin.

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