Considerations for Preparation Design and Facial Margin Placement: Part VIBy Frank Spear on February 4, 2019 | 1 comment
(Click the links for earlier articles in this series: Part I, Part II, Part III, Part IV, and Part V.)
When restoring the anterior teeth of relatively young patient, such as this woman in her early 20s, there are several things to consider. (Figure 1) The likelihood is that the restoration will need to be replaced, perhaps multiple times in her lifetime. Therefore, being as conservative as possible in any tooth reduction makes sense, while still obtaining an acceptable restorative and esthetic outcome.
And the likelihood is she will have some recession over time, the amount being highly variable depending on a number of factors. What this means to me is ideally try and make the restoration look acceptable with either a supragingival or equigingival margin, so that if recession occurs, nothing changes esthetically on the tooth because the margin wasn’t hidden anyway.
One way to address these concerns is to redo the Class IV composite, it would be very conservative, and the margins would be supragingival. In this patient I would consider that an excellent option, which I presented to she and her mother.
In addition, I presented the option of a very conservative porcelain veneer, which in my hands I believe I could get to look better, and I believe will also last longer before needing to be replaced. But I know several clinicians who might disagree with me on that topic.
In this patient the key areas to be considered if doing the veneer are depth of facial reduction and the location of the facial margin. (Figure 2)
Both will be influenced by the material selected to fabricate the veneer, which comes down to two options: feldspathic porcelain (stacked ceramics), or a monolithic material like Empress or e.max lithium disilicate, which is then stained or cut back and layered for enhanced esthetics.
The key in the restoration of this tooth is managing the junction esthetically between the end of the prep and the bulk of the restorative material. If the restoration is too translucent, the area just past the end of the prep will appear grey, like many composites do if their opacity isn’t managed well. On the other hand if the material is too opaque, the cervical aspect of the tooth color won’t appear natural.
The design of the preparation can significantly help both of these issues, performing minimal facial reduction .3 mm in the cervical 1/3 of the tooth, which leaves enamel to bond to, and will make the veneer highly translucent allowing the natural tooth color to show through. Followed by increased facial reduction, .7-.8 mm at the coronal portion of the prep, which makes the transition from cervical to all ceramic at the incisal much more gradual. (Figures 3, 4 and 5)
In this case I chose to use feldspathic porcelain because the technician has the advantage of being able to fire opacious dentin porcelain on the refractory die to replace the fractured tooth structure to the lingual, followed by layering a translucent enamel ceramic over the entire restoration. However, using e.max lithium disilicate over this same prep could have achieved excellent results as well. (Figure 6)
(Click this link to read more dentistry articles by Dr. Frank Spear.)
February 6th, 2019