Anterior Fracture: The i3d Layering Technique
Anterior Tooth Fracture in childhood is a frequent complication. It is usually provoked by the dental trauma and in most of the cases, direct adhesive restorations are the treatment of choice. As a consequence, succesful shade matching between composites and natural dentition is considered an even more difficut proccess when compared to indirect procedures due to the lack of a ‘try-in’ stage. The aim of this presentation is to share a novel aproach of an individual three-dimensional shade matching procedure utilizing contemporary composites.
A fractured central incisor was restored one year ago with contemporary composites. Patient was not satisfied because of a greyish overall tooth colour.
A 4-sequence treatment protocol was performed without success, even though during the verification phase, the restoration was refined for a second time.
CBCT data, already obtained for other surgical reasons (implant placement), were converted into .stl 3d printable files. Thus the three-dimensional structure of the central to be reproduced, was determined.
The 3D printed central was duplicated utilizing a custom made flask, to form an individual shade tooth-tab.
Enamel and dentin materials were verified and refined prior to the restorative procedure, yet for the fabrication of an individual three dimensional shade guide.
An individual three-dimensional shade guide (central incisor) was fabricated using the refined enamel and dentin materials. The linear thicknesses of enamel and dentin were already defined. The aim of the comparative shade matching between the natural and composite tooth was to accurately define which shade areas were acceptable. A spectroshade device was also used for this purpose. The middle third of the natural tooth presented a higher value, when compared to the shade tooth. A dentin material with higher chroma was selected for the final restoration.
In the cervical third, enamel linear thickness was 0.64mm (fig 12) while in the middle third the thickness was 0.72 mm (fig 13). A custom made measuring instrument of 0.75mm tip was used for controlling the thickness of both thirds.
The goal of the i3d technique is to keep the three-dimensional structure of the tooth to be reproduced. Within the defined thicknesses, materials may be corrected if necessary.
Some additional effects if existent, may be placed, between the dentinal body and the outer enamel surface.
The restoration was verified 1 week later, visually and instrumentally. The spectroshade device measured color difference below 2, which was considered an acceptable value (ΔE<2). The final restoration, even though presenting a similar level of luminosity or value, performs a lower level of fluorescence.
The final restoration was acceptable utilizing a repeatable layering technique.
The proposed individual three-dimensional layering technique (i3D layering technique) refines the shade matching procedure for a direct composite restoration by allowing for an initial preview of the chosen composite shades based on the real natural 3D anatomy of the respective tooth. In future, the described technique may be used for testing and development of more aesthetic composite materials as it allows for the direct comparison of the anatomically correct restorative copy to the original natural tooth.