Overview

The new world workshop of 2017 has made modifications on the American Academy of Periodontology consensus of 1999 in regard to the mucogingival deformities and conditions around teeth. These modifications are the following:

1. Periodontal biotype
   1. Thin scalloped
   2. Thick scalloped
   3. Thick flat
2. Gingival/soft tissue recession
   1. Facial or lingual surfaces
   2. Interproximal (papillary)
   3. Severity of recession (Cairo RT1,2,3)
   4. Gingival thickness
   5. Gingival width
   6. Presence of non‐carious cervical lesions (NCCL)/cervical caries
   7. Patient aesthetic concern (Smile Esthetics Index)
   8. Presence of hypersensitivity
3. Lack of keratinized gingiva
4. Decreased vestibular depth
5. Aberrant frenum/muscle position
6. Gingival excess
   1. Pseudo‐pocket
   2. Inconsistent gingival margin
   3. Excessive gingival display
   4. Gingival enlargement
7. Abnormal color

The additions included the definition of phenotype that included the gingival thickness (GT), gingival width, thickness of buccal bone, and the biotype. The presence and the absence of keratinized tissue (KT) have also been reviewed. On that latter, in 2015, both Kim et al. and Scheyer et al. concluded that lack of keratinized tissue, presence of an aberrant frenum, and lack of vestibule are not considered risk factors for gingival recession (GR) in conditions of optimum oral hygiene. However, later it was found that in the presence of gingival inflammation, lack of keratinized tissue has proven to be a predisposing factor for gingival recession (Merijohn 2016).

Also, in relation to the presence of gingival recessions a lot of the question that have been carried from the 1999 consensus have been re‐examined mainly the followings: Does gingival recession worsen with time? Are there any risks or consequences associated with the presence of recession? Is tooth position a risk factor? What is the role of the periodontal phenotype, and what is its effect on the incidence of recession or its progression? And finally, should the presence of gingival recession and phenotype be considered when planning orthodontic, restorative, and implant treatment?

Gingival recession has been defined as the apical shift of the gingival margin with respect to the cemento‐enamel junction (CEJ) (Pini Prato 1999). It is associated with attachment loss and exposure of the root surface to the oral environment. It is a frequent finding in adults that increases with age regardless of oral hygiene habits (Kassab and Cohen 2003). It was found that 88% of people aged ≥65 years and 50% of people aged 18–64 years have ≥1 site with gingival recession that can result in esthetic concerns and dentin hypersensitivity (Kassab and Cohen 2003). Exposing the root dentin to the oral environment can lead to carious (Nuttall et al. 2001) and NCCL, such as abrasions or erosions (Bartlett and Shah 2006; Pecie et al. 2011). Prevalence and severity of NCCL appear to increase with age (Bartlett and Shah 2006; Heasman et al. 2015; Pecie et al. 2011).

Although the etiology of gingival recessions remains unclear, several predisposing factors have been suggested (Cortellini and Bissada 2018):

1. Periodontal biotype and attached gingiva
2. The impact of toothbrushing
3. The impact of cervical restorative margins
4. The impact of orthodontics
5. Other conditions

The distinction among different biotypes that will be referred to as phenotypes, is based upon anatomic characteristics of components of the masticatory complex, including (i) gingival biotype, which includes in its definition gingival thickness (GT) and keratinized tissue width (KTW); (ii) bone morphotype (BM); and (iii) tooth dimension.

Tooth position in the alveolar process plays an important role. A buccally tilted tooth is frequently associated with thin gingiva (Cook et al. 2011) and a thin labial plate (Muller and Kononen 2005).

Thin phenotypes tend to develop greater gingival recession compared with thick phenotypes due to the presence of thin buccal bone or facial dehiscence, which influence the integrity of the periodontium, thereby constituting a risk when the tooth is subjected to orthodontic forces (Kassab and Cohen 2003; Kim and Neiva 2015; Zweers et al. 2014), restorative treatment or tooth extraction with subsequent implant placement (Cortellini and Bissada 2018; El Chaar et al. 2016a).

The presence of attached gingival tissue is considered important for maintenance of gingival health. The current consensus, based on case series and case reports (low level of evidence), is that about 2 mm of KT and about 1 mm of attached gingiva are desirable around teeth to maintain periodontal health, even though a minimum amount of keratinized tissue is not needed to prevent attachment loss when optimal plaque control is present (Kim and Neiva 2015). Furthermore, thin gingival biotype without gingival recession entails a greater risk for future development of gingival recessions, requiring an attentive follow‐up from the clinicians to prevent degradation (Cortellini and Bissada 2018). With respect to these cases with severe thin gingival biotype application of mucogingival surgery in high‐risk sites could be considered to prevent future mucogingival damage (Cortellini and Bissada 2018).

In 1987, Stetler and Bissada studied the effect of restorative margin placement on the periodontium and found that subgingival margin placement in patients presenting with minimal (<2 mm) or lack of gingiva resulted in greater gingival inflammation than those with a wider band of gingiva (Stetler and Bissada 1987). A recent systematic review reported clinical observations suggesting that sites with minimal or no gingiva associated with intrasulcular restorative margins were more prone to gingival recession and inflammation (Kim and Neiva 2015). Both authors recommend soft tissue augmentation to increase the width of keratinized tissue.

There is a possibility of gingival recession initiation or progression of recession during or after orthodontic treatment depending on the direction of the orthodontic movement (Bollen et al. 2008; Joss‐Vassalli et al. 2010). Several authors have demonstrated that gingival recession may develop during or after orthodontic therapy (Hall 1981; Maynard 1987; Renkema et al. 2013, 2015). The direction of tooth movement and the bucco‐lingual thickness of the gingiva may play important roles in soft tissue changes that occur during orthodontic treatment (Kassab and Cohen 2003; Kim and Neiva 2015).

Classifications

Proper diagnosis of gingival recession is critical for the prediction of successful treatment outcomes. In order to formulate an accurate diagnosis, it is essential to evaluate clinical measurements such as gingival recession, interdental clinical attachment level (CAL), interproximal bone level, and position of the tooth.

Measuring a gingival recession and interdental CAL rely on the detection of the CEJ. Determination of the location of the CEJ is especially important in cases presenting with previous restorations or NCCLs.

Determination of the CEJ

One of the primary goals of mucogingival surgery is to gain root coverage over areas of gingival recession. Gingival recession is defined as the apical movement of the free gingival margin (FGM) resulting in exposure of a portion of the root to the oral cavity (Cortellini and Bissada 2018). The main metric used to assess surgical success is complete root coverage (CRC), that is, the complete coverage of the exposed root surface to a point at the CEJ.

However, the CEJ is sometimes not readily detectable due to the presence of NCCLs. NCCLs may involve either the root surface, the enamel surface, or a combination of both surfaces. Should the NCCL only comprise the root surface, then mucogingival surgery alone is indicated. Should the NCCL only involve the enamel surface, restorative treatment alone is indicated. However, should the NCCL involve both surfaces, a joint restorative‐periodontal approach to treatment is most appropriate. This third situation poses the greatest challenge for achieving predictable esthetic and functional results because the reference point for root coverage, i.e. the CEJ, is obscured. Most importantly, the prevalence of tooth deformities associated with gingival recessions is very high (Pini‐Prato et al. 2010).

Cases in which CRC cannot be expected due to rotation, extrusion, or loss of interproximal clinical attachment (Miller III recession) are associated with greater complexity. In such cases, it may be more fruitful for the clinician and patient to anticipate maximum root coverage (MRC) versus CRC.

Utilizing MRC may also be applicable in cases of Miller I and II recession with unidentifiable CEJs. It should be noted that MRC should coincide with CRC in these cases, whereas in Miller III, MRC cannot predictably be coincident with CRC due to the presence of interproximal attachment loss.

Zucchelli et al. (2011) and coworkers have defined the level of MRC as the arc that joins the mesial and distal contact points and transitional line angles of a given tooth. In instances where the CEJ is obliterated, the line of MRC serves as a dimensional guideline to which the restorative dentist can re‐create the CEJ. Should the MRC line be coronal to the CEJ, mucogingival surgery is indicated as the sole therapy. However, should the MRC line be apical to the CEJ, restoration of the tooth is indicated to the level of the MRC, followed by mucogingival surgery.

Completing the restoration prior to surgery is beneficial for both the restorative and surgical dentist. For the restorative dentist, isolation and preparation of the site are more straightforward as the entire working field is supragingival. For the surgeon, the restorative margins provide a landmark for coronal advancement of the tissue and facilitate a stable, smooth surface for flap adaptation, ultimately optimizing wound healing.

In the 2017 world workshop, the CEJ is classified based on its detection with or without steps made by the presence or absence of NCCL as shown in Table 13.1.

In 2011, Cairo et al. introduced an alternative classification for gingival recession utilizing interproximal CAL as the primary factor when defining a recession type (RT) defect rather than the location of the mucogingival line (MGL). The classification system is defined as follows:

CEJ	Step	Descriptors
Class A	−	CEJ detectable without step
Class A	+	CEJ detectable with step
Class B	−	CEJ undetectable without step
Class B	+	CEJ undetectable with a step

• Recession Type 1(RT1): Gingival recession with no loss of interproximal attachment. Interproximal CEJ is clinically not detectable at both mesial and distal aspects of the tooth.
• Recession Type 2(RT2): Gingival recession associated with loss of interproximal attachment. The amount of interproximal attachment loss (measured from the interproximal CEJ to the depth of the interproximal sulcus/pocket) is less than or equal to the buccal attachment loss (measured from the buccal CEJ to the apical end of the buccal sulcus/pocket).
• Recession Type 3(RT3): Gingival recession associated with loss of interproximal attachment. The amount of interproximal attachment loss (measured from the interproximal CEJ to the apical end of the sulcus/pocket) is greater than the buccal attachment loss (measured from the buccal CEJ to the apical end of the buccal sulcus/pocket).

While the Cairo classification is today preferred over the classic Miller classification (Table 13.2) as it is considered to be in greater accordance with the new advancements of root coverage therapy, it nevertheless fails to include important factors in achieving treatment success such as interproximal bone loss, tooth position (over‐eruption, tilt) and root pro‐eminence.

Class I		Recession that does not extend beyond the mucogingival junction with no loss of interproximal bone	Class III		Recession that extends to or beyond the mucogingival junction with some periodontal attachment loss or malpositioning of teeth
Class II		Recession that extends to or beyond the mucogingival junction with no loss of interproximal bone	Class IV		Recession that extends to or beyond the mucogingival junction with severe periodontal attachment loss and/or severe malpositioning of teeth

Diagnostic and Treatment Considerations Based on Classification of Periodontal Biotypes, Gingiva Recession, and Root Surface Conditions

Pursuant to the world workshop, a diagnostic table integrating recession type (RT), gingival recession (GR), keratinized tissue width (KTW), gingival thickness (GT), the detection of the CEJ and the absence or presence of concavities (Table 13.3).

This table is meant to help orient the clinician when determining the best course of treatment for a particular patient. For example, in cases that currently lack gingival recession but present with a thin phenotype thereby predisposing to future recession defects, the clinician may elect to conservatively wait and monitor the recession or to intervene by changing the phenotype especially if the patient will undergo future orthodontic treatment.

Surgical Management of Mucogingival Deficiencies

The principles that support successful surgical treatment of mucogingival deformities remain consistent regardless of the elected treatment modality. These fundamental principles include flap management and integrity, graft stabilization, and an understanding of wound healing.