Soft Tissue Management. Ariel J. Raigrodski

in increased crown height. The thickness of the soft tissue correlates to the prevention of soft tissue recession. The risk of developing recession is increased in the presence of thin tissue when the tooth is being moved out of the alveolar bone housing. If mucogingival surgery is considered in order to prevent or reduce the risk of developing recession, it should be aimed at increasing the thickness of marginal soft tissue rather than only the width of keratinized gingiva.¹⁰³

       Implant therapy

      In the case of dental implants, there is evidence indicating that the tissue phenotype is a key element for predictable and successful esthetic outcomes. Thin gingival tissues are more susceptible to marginal bone loss, angular bone defects, and recession, while thick gingival tissue results in the maintenance of stable crestal bone and is less prone to recession around dental implants.^59,104,105

       Restorative procedures

      A thick periodontium reduces the risk of gingival recession when the finish line of the crown preparation for a ceramic crown or a porcelain laminate veneer is placed subgingivally for esthetics. It can mask and eliminate the grayish discoloration from metal-ceramic restorations with metal collars or disappearing margins. The placement of retraction cord can be accomplished with a reduced risk of inducing recession, which may lead to disparate gingival levels and compromise the esthetic outcome.¹⁰⁶ With thin tissue phenotypes, the risk of inducing recession is increased, mainly during impression procedures. Clinicians may opt to use metal-free restorations such as ceramic crowns and fixed dental prostheses. When the finish line is placed subgingivally, it is placed more conservatively than with metal-ceramic restorations. Therefore, the likelihood of trauma to the tissue is diminished, and the color of the soft tissue, mainly in terms of brightness, will be uncompromised even though the restoration may be slightly visible through the thin soft tissue.¹⁰⁷

      In summary, an accurate evaluation of the soft tissue morphology and phenotype not only helps clinicians predict therapeutic outcomes but also helps them determine the most appropriate periodontal and restorative management, leading to more favorable and predictable treatment outcomes.^97,100

      Gingival phenotype assessment

      Many different methods are available for gingival phenotype assessment. An ideal method should be simple to use, accurate, reproducible, and noninvasive. It should allow clinicians to predict risks in terms of soft tissue treatment complications and enhance the customization of therapy for each patient. The gingival thickness can be evaluated by invasive methods such as transgingival probing as well as by noninvasive methods such as visual evaluation of the gingiva, periodontal probing, direct measurement with a caliper immediately postextraction, and cone beam computed tomography (CBCT), if indicated.^{91,95–97,110}

       Visual evaluation of the gingiva

      Visual evaluation was one of the first methods used to evaluate tissue phenotype.^86,87 Because of its simplicity, it is widely used in clinical practice settings to identify high-risk patients. While simple, this method may lack accuracy.

      Accuracy of a visual inspection method for identification of three different groups of patients (thin scalloped, thick flat, thick scalloped) was evaluated based on clinical photographic slides.¹¹¹ The thick flat phenotype was relatively easily identified, but about half of the thin scalloped cases were misidentified. Precise identification of different phenotypes by means of visual evaluation was not reliable, as half of the patients at high risk were overlooked. In a similar study, 124 clinicians were asked to assign each of 53 patients to one of three phenotypes: thin scalloped, thick flat, or thick scalloped.⁹⁷ The results showed that visual evaluation was not very effective in identifying different phenotypes, with less than 50% probability of identifying the correct cluster.

       Periodontal probing

The gingival tissue around teeth and implants can be classified as thick or thin by assessing tissue translucency. A periodontal probe is positioned into the sulcus, and the clinician assesses whether or not the underlying periodontal probe can be seen through the tissue. If the outline of the probe is visible through the gingiva, the tissue is considered to be thin.^91,112 This method is extremely simple, minimally invasive, reliable, objective, and reproducible^{89,97,112,113} (Figs 1-10 and 1-11).

Fig 1-10 (a) Facial view of a tooth prepared for a zirconia-based ceramic crown. (b) Crown at the 4-year recall. Note the visual appearance of the tissue, looking relatively flat and thick. (c) The outline of a periodontal probe positioned into the sulcus is visible through the gingiva, demonstrating that the tissue is thin and translucent. (Ceramics: Andreas Saltzer.)

Fig 1-11 Facial view of a failing tooth planned to be restored with an implant-supported restoration. The outline of a periodontal probe positioned into the sulcus is not visible through the gingiva, demonstrating that the tissue is thick and opaque.

       Transgingival probing

This is a very simple method in which a periodontal probe or endodontic file is used to measure the gingival thickness, usually at a point 2 mm apical to the gingival margin. However, this method is limited by the precision of the probe, which is usually rounded to the nearest 0.5 mm; the angulation of the probe penetration through the soft tissue; distortion of the tissue during the probing; a need for anesthesia; and the invasive nature of this tissue-penetrating procedure^112–114 (Figs 1-12 and 1-13). Alternatively, the use of an endodontic file with a stop has been advocated as well.

Fig 1-12 Transgingival probing of less than 1 mm at a point 2 mm apical to the facial free gingival margins confirms that the tissue is thin, as demonstrated in Fig 1-10c. (Ceramics: Andreas Saltzer.)

Fig 1-13 Transgingival probing of just less than 2 mm at a point 2 mm apical to the facial free gingival margins confirms that the tissue is thick, as demonstrated in Fig 1-11.

       Direct measurement with a caliper

      This method is limited for tissue assessment prior to immediate implant placement. A comparison was made among three different methods of evaluation of gingival phenotype around maxillary anterior teeth scheduled for extraction and immediate implant placement. A statistically significant difference was noted between visual inspection and both periodontal probing and the direct caliper measurement method. However, no significant difference was noted between periodontal probing and direct caliper measurement.⁹¹ The only drawback of the caliper method is that it cannot be used for presurgical evaluation, because it can only be used at the time of tooth extraction.^112,115,116

       CBCT scans of tissue thickness

      CBCT scans are used extensively for three-dimensional imaging of hard tissue for orthodontics, endodontics, extractions, and especially for implant-related procedures.¹¹⁷