The Healthier Paradigm: Supragingival Minimally Invasive Adhesive Dentistry – The Benefits
Subgingival margins are preventable. Nevertheless, most clinicians would say, “I would leave the margins above the gum if I were able!” The previous chapter explained why traditional mechanically retained dentistry considers subgingival margins normal. Supragingival minimally invasive adhesive dentistry is a mode of restorative dentistry which uses a number of modern techniques, and the benefits of adhesive dentistry, to intentionally avoid crowns or any restorative procedure which may cause unnecessary subgingival margin. It strives to retain restorative margins supragingivally and to preserve as much tooth as possible, making it a healthier form of restorative dentistry. With these techniques, it is also possible to limit and repair the damage when subgingival caries or margins are already present.
Supragingival minimally invasive adhesive dentistry comes with numerous advantages. While the desire to stay supragingival in dentistry is universal, the difference is the systematic approach, and the many specialized techniques and absolute commitment to supragingival minimally invasive restorations. Supragingival margins in fact make restorative dentistry easier for the clinician, healthier for the patient, more esthetically pleasing, and provide for long lasting predictable results (Figures 2.1a–g, 2.2a,b).
Esthetic demands from patients led to an increased use of new tooth-colored materials. Adhesives have changed the rules and allow the dentist to provide minimally invasive esthetic dentistry, never considered possible before [1,2,3,4,5]. When initially introduced, bonded restorations posed challenges for dental professionals. Bonded restorations seemed less predictable and filled with complications, such as postoperative sensitivity and restoration fractures, leading to their limited use. Lack of knowledge and trust in adhesion led to less than optimal use of these new tooth-colored materials. Instead of using tooth-conserving adhesion techniques, traditional mechanically retained techniques were employed, which it is often counterproductive.
Over time, newer materials, improved restorative and adhesion techniques, and the realization of previously hidden benefits, especially supragingival margins [6,7,8,9], have allowed these restorations to live up to their full potential [10,11,12]. Adhesion allows for the preservation of healthy tooth structure and since remaining dentin thickness correlates with continued tooth vitality , bonded restorations preserve the vitality of the tooth (Figure 2.3a–c).
It must be emphasized that although partial coverage bonded restorations such as onlays and veneers are used in dentistry, they are extremely under-used. The overwhelming majority in the profession consider partial coverage bonded restorations as a limited alternative to full crowns, indicated only when a number of requirements are fulfilled (Figures 2.4a,b, 2.5a–d) [14,15,16,17,18]. Keeping restorative margins supragingival has been left to chance, as a suggested option only where possible. In the cases where is not easily achievable, full coverage becomes the preferred choice. Until now, no specific protocol or set of techniques have been advocated to prevent subgingival margins. The supragingival minimally invasive adhesive dentistry approach is different. Progress in understanding adhesive dentistry, added to the great value placed on the health of the periodontium, make supragingival margins a priority, and minimally invasive partial coverage restoration, direct and indirect, becomes the choice in every case, except in teeth already cut for crowns.
While it might be thought that because traditional mechanically retained restorations have a longer history and are thus more predictable, easier and maybe even healthier, the following section presents the argument that supragingival minimally invasive adhesive dentistry is in fact a better restorative alternative for the patient and the dentist. Principles and techniques for supragingival dentistry and a supragingival protocol for achieving supragingival margins are considered in detail in subsequent chapters.
It may be thought that traditional restorative techniques such as full crowns are easier than partial coverage bonded restorations, but in fact the opposite is true: keeping margins supragingival is key to simple bonded restorations.
The preparation of the tooth for supragingival bonded restoration is considerably more simple. The need for exacting mechanical retention features such as axial reduction with correct taper, and exact boxes, shoulders and offsets during preparations, is eliminated, as adhesive retention is predictable and does not require any retention or resistance forms, thus greatly simplifying the preparation process (Figure 2.6a–c). The very difficult atraumatic subgingival margin placement technique is also eliminated. All of the above make supragingival adhesive dentistry preparation far less complicated and faster to perform correctly, compared with traditional crown preparation (Figure 2.7a,b) [19,20]. Proper preparation leads to easy cementation when the restorative margins are kept supragingival, and the use of a targeted supragingival protocol ensures that the risk of contamination while cementing or bonding is virtually eliminated.
Taking an impression of a subgingival margin is one of the most challenging procedures that dentists perform (Figure 2.8a,b) [21,22,23]. Since subgingival margins are equally difficult to reproduce with digital scanners, digital impressions will also greatly benefit from supragingival margins (Figure 2.9a,b). Supragingival restorative techniques make the task of taking impressions easy, thus making every ensuing step more predictable.
When margins are kept above the gingival level, temporaries are easier to make because the margins are clear and visible. Temporary cementation can easily be done on a clean uncontaminated tooth and removal of the temporary cement is easy and predictable, thus allowing for better results, and leaving healthier gingiva at the time of permanent cementation (Figure 2.10a,b).