A new classification system for gingival and palatal recession.

Various classifications have been proposed to classify gingival recession. Miller's classification of gingival recession is most widely followed. With a wide array of cases in daily clinical practice, it is often difficult to classify numerous gingival recession cases according to defined criteria of the present classification systems. To propose a new classification system that gives a comprehensive depiction of recession defect that can be used to include cases that cannot be classified according to present classifications. A separate classification system for palatal recessions (PR) is also proposed. This article outlines the limitations of present classification systems and also the inability to classify PR. A new comprehensive classification system is proposed to classify recession on the basis of the position of interdental papilla and buccal/lingual/palatal recessions.

INTRODUCTION

Gingival recession is defined as “the displacement of marginal tissue apical to the cemento-enamel junction (CEJ).”[1] The term “marginal tissue recession” is considered to be more accurate than “gingival recession,” since the marginal tissue may have been alveolar mucosa.[23] Gingival recession is present at most of the ages, starting early in some populations.[4] Löe et al. stated a hypothesis that there was more than one type of gingival recession and probably several factors determining the initiation and development of these lesions on the basis of the occurrence and levels of gingival recession in two cohorts of individuals participating in parallel longitudinal studies in Norway (1969-1988) and Sri Lanka (1970-1990), covering the age range from 15 years to 50 years.[5] In another study of 1,003 children, aged 15 years, it was found that the highest degree of association with the local etiological factors was that between recession and the width of keratinized gingiva.[6]

Most of the classifications of gingival recession are unable to convey all the relevant information related to marginal tissue recession. This information is important for shaping diagnosis, prognosis, treatment planning, but also communication between clinicians. Furthermore, with a broad variety of cases with different clinical presentations, it is not always possible to classify all gingival recession defects according to present classification systems. Palatal recessions (PR) have not been classified.

CLASSIFICATIONS OF GINGIVAL RECESSION

One of the 1st classifications to be proposed was by Sullivan and Atkins.[7] The basis for the gingival recession classification was the depth and width of the defect. The four categories were: Deep wide, shallow wide, deep narrow, and shallow narrow.

Miller proposed a classification system in 1985 [Table 1] and probably is the most widely used for describing the gingival recession.[8]

Table 1

Comparative table of Miller's classification with the proposed classifications

Class I: Marginal tissue recession not extending to the mucogingival junction (MGJ). No loss of interdental bone or soft-tissue

Class II: Marginal recession extending to or beyond the MGJ. No loss of interdental bone or soft-tissue

Class III: Marginal tissue recession extends to or beyond the MGJ. Loss of interdental bone or soft-tissue is apical to the CEJ, but coronal to the apical extent of the marginal tissue recession

Class IV: Marginal tissue recession extends to or beyond the MGJ. Loss of interdental bone extends to a level apical to the extent of the marginal tissue recession.

An index for gingival recession[9] and modification of Miller's classification[10] had also been proposed earlier.

In 1998 Nordland and Tarnow[11] proposed a classification system regarding the papillary height based on three anatomical landmarks (a) the interdental contact point, (b) the apical extent of the facial CEJ, and (c) the coronal extent of the proximal CEJ.

Limitations

Miller's classification used the criteria of diagnosis and prognosis for classification.[12] Although Miller's classification has been used extensively, there are limitations that need to be considered:

The reference point for classification is MGJ.[12] The difficulty in identifying the MGJ creates difficulties in the classification between Class I and II.[12] There is no mention of presence of keratinized tissue. A certain amount of keratinized gingiva (in the form of free gingiva) will be evident in any tooth with the gingival recession; the marginal tissue recession cannot extend to or beyond the MGJ. In such a case, Class II cannot be a distinct class and Classes I and II would represent a single group.[12]

In Miller's Class III and IV recession, the interdental bone or soft-tissue loss is an important criterion to categorize the recessions. The amount and type of bone loss has not been specified. Mentioning Miller's Class III and IV doesn't exactly specify the level of interdental papilla and amount of loss. A clear picture of severity of recession is hard to project.

Class III and IV categories of Miller's classification stated that marginal tissue recession extends to or beyond the MGJ with the loss of interdental bone or soft-tissue is apical to the CEJ. The cases, which have inter-proximal bone loss and the marginal recession that does not extend to MGJ cannot be classified either in Class I because of inter-proximal bone or in Class III because the gingival margin does not extend to MGJ.[12] Two such cases have been presented in Figure 1a and b. These cases show interdental bone/soft-tissue loss, but the facial recession is not extending to or beyond the MGJ. These cases in the true sense cannot be classified as Miller's Class III.

Figure 1

(a and b) Clinical photographs with interdental and marginal tissue recession. Marginal tissue recession does not extend to mucogingival junction

Miller's classification doesn't specify facial (F) or lingual (L) involvement of the marginal tissue.

Recession of interdental papilla alone cannot be classified according to the Miller's classification. It requires the use of an additional classification system.

Classification of recession on palatal aspect is another area of concern. The difficulty of the applicability of Miller's criteria on the palatal aspect of the maxillary arch can be reasoned out to the fact that there is no MGJ on palatal aspect. Therefore, a classification is required, which specifies the type of recession and can also quantify the amount of loss. The classification should be able to convey the status of the gingival recession and the severity of the condition on palatal aspect. Recession on palatal aspects changes the overall diagnosis and prognosis of a case. Mucogingival treatment of the recession may be required for reasons other than esthetics.

Miller's classification[8] estimates the prognosis of root coverage following grafting procedure. Miller stated that 100% coverage can be anticipated in Class I and II recessions, partial root coverage in Class III and no root coverage in Class IV.[8] Pini-Prato stated that anticipation of 100% root coverage does not mean that it will occur.[12] Root coverage percentage ranging from 9% to 90% have been reported by different authors in Class I and II recessions using different techniques.[12131415] Outcome of treatment may depend on other prognostic factors and categorization to predict the outcomes of root coverage in Classes I and II are not correct.[12]

Another classification had been proposed based on the assessment of clinical attachment level at both buccal and interproximal sites.[16]

Considering the above limitations, a new classification system is being proposed which is more detailed, informative and lucid. This classification system is based on an amalgamation of certain criteria of Miller's[8] classification with the certain features of Nordland and Tarnow's[11] classification. A distinct classification for gingival recession on palatal aspect is also being proposed.

Proposed classification of gingival recession

This classification can be applied for facial surfaces of maxillary teeth and facial and lingual surfaces of mandibular teeth. Interdental papilla recession can also be classified according to this new classification. Class I deals with marginal tissue recession with no loss of interdental bone or soft-tissue. Class II and III deal with the loss of interdental bone/soft-tissue with/without marginal tissue recession [Table 1].

Class I: There is no loss of interdental bone or soft-tissue. This is sub-classified into two categories:

Class I-A: Gingival margin on F/L aspect lies apical to CEJ, but coronal to MGJ with attached gingiva present between marginal gingiva and MGJ [Figure 2a]

Figure 2

(a) Schematic representation of Class I-A. (b) Schematic representation of Class I-B

Class I-B: Gingival margin on F/L aspect lies at or apical to MGJ with an absence of attached gingiva between marginal gingiva and MGJ [Figure 2b].

Either of the subdivisions can be on F or L aspect or both (F and L):

Class II: The tip of the interdental papilla is located between the interdental contact point and the level of the CEJ mid-buccally/mid-lingually. Interproximal bone loss is visible on the radiograph. This is sub-classified into three categories:

Class II-A: There is no marginal tissue recession on F/L aspect [Figure 3a]

Figure 3

(a) Schematic representation of Class II-A. (b) Schematic representation of Class II-B. (c): Schematic representation of Class II-C

Class II-B: Gingival margin on F/L aspect lies apical to CEJ but coronal to MGJ with attached gingiva present between marginal gingiva and MGJ [Figure 3b]

Class II-C: Gingival margin on F/L aspect lies at or apical to MGJ with an absence of attached gingiva between marginal gingiva and MGJ [Figure 3c].

Either of the subdivisions can be on F or L aspect or both (F and L).

Class III: The tip of the interdental papilla is located at or apical to the level of the CEJ mid-buccally/mid-lingually. Interproximal bone loss is visible on the radiograph. This is sub-classified into two categories:

Class III-A: Gingival margin on F/L aspect lies apical to CEJ, but coronal to MGJ with attached gingiva present between marginal gingiva and MGJ [Figure 4a]

Figure 4

(a) Schematic representation of Class III-A. (b) Schematic representation of Class III-B

Class III-B: Gingival margin on F/L aspect lies at or apical to MGJ with an absence of attached gingiva between marginal gingiva and MGJ [Figure 4b].

Either of the subdivisions can be on F or L aspect or both (F and L).

Marking guidelines

If a tooth presents marginal tissue recession only on facial (F) or lingual (L) aspect, the class of recession should be followed with the word F or L. When the gingival margin is coronal to the CEJ, the clinician must detect the CEJ through tactile exploration with the probe tip. The tip of the probe is positioned at 45° angle to the tooth and moved slowly beneath the gingival margin to detect the CEJ with the tactile sensation. For example, if mandibular central incisor presents with a recession of only marginal tissue on facial aspect not extending to MGJ and no interdental bone loss, it should be classified as Class I-A (F). If similar marginal tissue recession is also present on lingual aspect of the same tooth, it should be marked as Class I-A (F, L). The more apical level of interdental papilla on interproximal aspect (mesial or distal) would decide the category to which the recession should be classified in a case where different levels of recession are observed on the mesial and distal aspects of the same tooth. The use of more apical level of interdental papilla to classify gives a more appropriate idea of severity of the situation.

According to the new classification, the photograph in Figure 1a would be classified as Class II-B (F) on maxillary right central and lateral incisors.

Classification of palatal gingival recession

The position of interdental papilla remains the basis of classifying gingival recession on palatal aspect. The criteria of sub-classifications have been modified to compensate for the absence of MGJ [Table 1].

PR-I deals with marginal tissue recession on palatal aspect with no loss of interdental bone or soft-tissue.

PR-II and PR-III deal with the loss of interdental bone/soft-tissue with marginal tissue recession on palatal aspect.

Palatal recession-I

There is no loss of interdental bone or soft-tissue. This is sub-classified into two categories:

PR-I-A: Marginal tissue recession ≤3 mm from CEJ [Figure 5a]

Figure 5

(a) Schematic representation of palatal recessions (PR-I-A). (b) Schematic representation of PR-I-B

PR-I-B: Marginal tissue recession of >3 mm from CEJ [Figure 5b].

Palatal recession-II

The tip of the interdental papilla is located between the interdental contact point and the level of the CEJ mid-palatally. Interproximal bone loss is visible on the radiograph. This is sub-classified into two categories:

PR-II-A: Marginal tissue recession ≤3 mm from CEJ [Figure 6a]

Figure 6

(a) Schematic representation of palatal recessions (PR-II-A). (b) Schematic representation of PR-II-B

PR-II-B: Marginal tissue recession of >3 mm from CEJ [Figure 6b].

Palatal recession-III

The tip of the interdental papilla is located at or apical to the level of the CEJ mid-palatally. Interproximal bone loss is visible on the radiograph. This is sub-classified into two categories:

PR-III-A: Marginal tissue recession ≤3 mm from CEJ [Figure 7a]

Figure 7

(a) Schematic representation of palatal recessions (PR-III-A). (b) Schematic representation of PR-III-B

PR-III-B: Marginal tissue recession of >3 mm from CEJ [Figure 7b].

If marginal tissue recession of 4 mm with no interdental bone loss is present on palatal aspect of maxillary central incisor, it is marked as PR-I-B. If marginal tissue recession on facial aspect of maxillary central incisor confirms to Class I-A and palatal aspect confirms to PR-I-B, then it should be marked as Class I-A (F) and PR-I-B against that tooth. The more apical level of interdental papilla on interproximal aspect (mesial or distal) would decide the category to which the recession should be classified in a case where different levels of recession are observed on the mesial and distal aspects of the same tooth. The use of more apical level of interdental papilla to classify gives a more appropriate idea of severity of the situation.

Recession status chart

The chart shown in Table 2 can be used to mark recession category. An arrow amid the teeth of involved papilla can mark the papilla.

Table 2

Recession status chart

DISCUSSION

The aim of this classification is to answer the pitfalls of the currently used classification systems for recession and to include or help the clinicians to classify those cases, which cannot be categorized into a particular class with any of the current classifications. The limitations of Miller's classification result in insufficient depiction of clinical condition. Partial depiction leads to an erroneous diagnosis, prognosis, and hence treatment planning.

The criteria suggested in the new classification assist to classify a large number of cases that cannot be distinctly placed into any category according to the current classification systems. The proposed classification system would give a broader depiction of recession. The mere mention of category would explain the position of interdental papilla and facial/lingual/palatal involvement. The cases with the varied clinical pictures can be easily classified, and the findings can be recorded in an elaborate and precise manner.

Categorization of recession into groups cannot predict the treatment plan and amount of final root coverage. Although Miller's landmark article not only suggested prognosis, but also stated that “the amount of root coverage can be determined pre-surgically using a periodontal probe.”[8] This hypothetical assertion by Miller has not been validated.[12] Miller's assumption in his classification, that 100% root coverage can be anticipated in Class I and II is only speculative and does not mean that 100% coverage will occur.[12] Results from various studies for Classes I and II recession treatment have a range from 9% to 90% of root coverage.[1314] The prediction of the outcomes of root coverage in Classes I and II is not correct and impractical. According to Miller,[8] partial root coverage is expected in Class III recession, although complete root coverage has been achieved in Class III recessions.[17] The results of various studies, many of which are contrary to the assumptions of Miller, show that categorization in a specific group cannot determine prognosis and treatment plan.

Pini-Prato stated, “The prognostic anticipation of a certain amount of root coverage is a complex process that should consider data from reliable studies and cannot be drawn from theoretical considerations.”[12] Difficulty in determining prognosis and treatment plan based on the classification categories, stems from the fact that prognosis depends on many factors other than the clinical features of the disease. The treatment plan and amount of root coverage not only depends on the clinical condition of the tissues, but also on patient-related factors (e.g., habits), tooth/site-related (e.g., recession depth, width), and technique-related (e.g., presence or absence of releasing incisions) prognostic factors.[12] Mucogingival therapy is very technique sensitive and surgeon's dexterity can also affect the extent of root coverage.[12]

The multiplicity of prognostic factors and their interactions affects the overall percentage of root coverage. The classification is based on presence/absence of specific clinical features and cannot alone determine the amount of root coverage. The diversity of prognostic factors prevents anticipation of probable percentage of root coverage in the new classification.

Periodontal diagnosis and monitoring rely upon clinical parameters to a large extent.[18] The disease classification should be able to provide clinically beneficial distinctions between conditions that have comparable clinical presentations. Application of more descriptive and detailed classification that requires recording of additional parameters may require additional time, but the clinical picture presented by details would have broader interpretation of recession which would be more beneficial and informative for the clinicians for communication and to arrive at a correct diagnosis. The additional time required to implement this classification will also aid in classifying cases that cannot be classified presently and provide clinically beneficial distinctions.

The purpose of statistical methods is to provide an objective explanation of scientific evidence.[19] Statistical analysis is a mathematical model based on hypothesis testing and in literature provides confirmation that inferences drawn by the author are not well explained by chance.[20] The statistical modeling of data from the periodontal research requires special attention because of the multiple measurements made for each subject.[21] A range of statistical methods for the analysis of such data are available.[21] Use of advanced statistical methods has proven valuable in medical research.[22] Computationally intensive methods have been developed for the effective modeling of complex biomedical data sets, exploration of data sets to discover interrelationship of variables and select appropriate statistical models for analysis.[22]

The application of this new classification during the examination, diagnosis, and communication among clinicians would definitely be more informative, expressive and would have more clinical value and relevance.

CONCLUSION

Although, various classification systems are in use and each system has an advantage of its own. No classification system can be complete and everlasting; with time and its continual use one realizes the advantages and disadvantages of each system. This classification is a step towards refining the existing drawbacks of the current classification. An attempt has been made so that the new system can be applied to a wider variety of cases to provide more accurate and detailed clinical picture.