Invisible Margins in Anterior Composites, Tips&Tricks
Making margins invisible in anterior composite restorations, completely integrating different materials such as composite and tooth enamel has always been a challenge for dental practitioners. With composite resins often makes a dentist feel, that there is a visible interface between the restoration and the tooth tissue after the restoration is completed. A lot of clinicians also refer to it as the white line at the interface. This can be mild to rather pronounced and cannot be accepted.
This could happen due to various reasons and at attempt to identify and overcome those has been shown in this case.
A 40 micron diamond is used to smoothen out the jagged margins of the tooth and create a smooth bevel at least 2mm beyond the fracture line. This softens the edges and rounds off the fractured enamel prisms.
The tooth is etched and the adjacent teeth are protected with Teflon tape at this point in time. Selective etching is advised and in this case 37%phosphoric acid was used for 30 seconds on the enamel and 15 seconds on the dentine
After removing the excess dentine do not leave a sharp interface between the dentine and the enamel. Using appropriate brushes one can ramp up the dentine mass almost to the top very close to the enamel surface. This ensures light reflection and transmission from and through a gradient and does not appear as an abrupt color shift in the final restoration.
It is often seen that when this step is missed, patients come back with discolored margins and in some case discolored restoration quite soon after they are done. A 1 minute final curing through a water soluble fluid or gel ensures a much better conversion and avoids marginal deterioration of the restoration at its interface with the tooth.
The final polishing is carried out using rubbers, silicone coated discs and giffy brushes using a diamond polishing paste, but what is very important to keep in mind is to create an adequate macro and micro-texture on the tooth surface. This can be created with the right diamond bur on a contra-angle hand piece (Perioset Flame Bur). This results in the light reflection, refraction and scattering to happen close to the natural tooth here by making the interface difficult to decipher.
In order to make the margins of the restoration blend with the tooth it is suggested to smoothen out the rough fractured enamel prisms with a long wavy bevel, etch and bond beyond the bevel, ramping up the composite resin, final curing through an oxygen inhibited gel and creating appropriate texture.
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