Comparison of the clinical applicability of Miller's classification system to Kumar and Masamatti's classification system of gingival recession.

BACKGROUND: The aims of the present study were to (i) Find the percentage of recession cases that could be classified by application of Miller's and/or Kumar and Masamatti's classification of gingival recession, and (ii) compare the percentage of clinical applicability of Miller's criteria and Kumar and Masamatti's criteria to the total recessions present.
MATERIALS AND METHODS: A total of 104 patients (1089 recession cases) were included in the study wherein they were classified using both Miller's and Kumar and Masamatti's classification systems of gingival recession. Percentage comparison of the application of both classification systems was done.
RESULTS: Data analysis showed that though all the cases of the recession were classified by Kumar and Masamatti's classification, only 34.61% cases were classified by Miller's classification. 19.10% cases were completely (having only labial/buccal recession) classified. In 15.51% (out of 34.61%) cases, only buccal recession was classified according to Miller's criteria and included in this category, although these cases had both buccal and lingual/palatal recessions. Furthermore, 29.75% cases of recession with interdental loss and marginal tissue loss coronal to mucogingival junction (MGJ) remained uncategorized by Miller's classification; categorization of palatal/lingual recession was possible with Kumar and Masamatti's classification.
CONCLUSION: The elaborative evaluation of both buccal and palatal/lingual recession by the Kumar and Masamatti's classification system can be used to overcome the limitations of Miller's classification system, especially the cases with interdental loss and having marginal tissue loss coronal to MGJ.

INTRODUCTION

Periodontal diseases in general and gingival recession, in particular, have been subject of intense analysis in terms of classification. Various classifications of periodontal diseases[12] as well as gingival recession have been proposed over a period of time.[3]

Gingival recession is defined as “the displacement of marginal tissue apical to the cemento-enamel junction (CEJ).[4] It is one of the signs of the periodontal disease and has been found to be existing at most of the ages, beginning early in certain populations.[5] Gingival recession is important not only from an esthetic point of view, but loss of gingival tissue may result in root sensitivity, cemental erosion, and root caries.

Many classifications of recession have been reported in the literature. In 1968, Sullivan and Atkins classified soft tissue defects in mandibular incisors into four classes: “Narrow,” “wide,” “shallow,” and “deep.”[6] Miller in 1985 proposed a classification system which is probably the most commonly employed system to classify gingival recession and divided it into four categories.[7] Class I marginal tissue recession does not extend to the mucogingival junction (MGJ) with no periodontal loss (bone or soft tissue) in the interdental area, and 100% root coverage can be anticipated. Class II recession extends to or beyond the MGJ with no periodontal loss (bone or soft tissue) in the interdental area, and 100% root coverage can be anticipated. Class III recession extends to or beyond the MGJ with bone or soft tissue loss in the interdental area, or there is malpositioning of the teeth which prevents the attempting of 100% root coverage. Partial root coverage can be anticipated. Class IV recession extends to or beyond the MGJ with the bone or soft tissue loss in the interdental area and/or malpositioning of teeth is so severe that root coverage cannot be anticipated.

Other classifications, which have been proposed to classify recession defects, include Smith's index for gingival recession,[8] Mahajan's classification,[9] Cairo et al.'s classification,[10] and Kumar and Masamatti's classification.[3] Nordland and Tarnow proposed a classification system for the papillary height.[11]

Despite being extensively used, certain limitations of Miller's classification have been pointed out in recent literature.[312] Pini-Prato stated “the noncritical and widespread use of the Miller classification should be evaluated carefully with sound clinical trials on gingival recessions and root coverage. New classification systems of gingival recessions should be provided on the basis of the characteristics of suitable taxonomy, on the basis of information from more recent scientific evidence and then validated by reliability studies for appropriate application in clinical practice”.[12]

Considering the limitations of Miller's classification,[7] Kumar and Masamatti[3] proposed a new classification system in 2013 for gingival and palatal recession [Table 1]. The level of the interdental papilla (IDP) in relation to the CEJ and the level of the marginal recession were used as the basis for this new classification. The new classification system is more comprehensive, informative, and tries to overcome the limitations of Miller's classification.

Table 1

Kumar and Masamatti's classification

The aims of the present study were:

To find the percentage of recession cases that could be classified by application of Miller’s[7] classification of gingival recession

To find the percentage of recession cases that could be classified by application of Kumar and Masamatti’s[3] classification of gingival recession

To compare the percentage of the clinical applicability of Miller's criteria and Kumar and Masamatti's criteria to the total recessions present.

MATERIALS AND METHODS

Before the start of the study, all the examiners were informed, instructed and trained to use Miller’s[7] as well as Kumar and Masamatti’s[3] classification system by the first author. Twenty-five cases of the gingival recession were assessed by each examiner individually (authors 2–6) along with the first author. Each case was evaluated twice; once by the first author and then by one of the examiners. Other examiners were blinded to gingival recession recordings of the first author. The results were evaluated, and comparisons were made between the recordings of the first author and each of other examiners. Any differences in the recordings were discussed with the individual examiner (in the presence of all other examiners). All necessary explanations were provided individually to each examiner (in the presence of all other examiners) before the study. The presence of other examiners was mandatory at the time of discussion between the first author and any of the other examiners (2–6) so that conversation would be helpful to each examiner in diagnosing the cases. The seventh author maintained and analyzed all the data. All the authors also contributed to concept and design of the study, revising the manuscript critically for intellectual content and finally approving it.

The applicability of the recession classifications was examined clinically without the help of any radiographic aids. The recessions were scored, as they were visible clinically.

All the patients reporting to the outpatient department of Department of Periodontics were examined for the presence or absence of gingival recession (buccal/palatal/lingual [B/P/L]). All the patients having recession were informed about the study. The subjects who agreed to be a part of the study signed a written informed consent. An ethical clearance was taken from institutional review board before the start of the study. The inclusion criterion was the presence of gingival recession (B/P/L). The cases were classified using both the classification systems (Miller's and Kumar and Masamatti’s) by six examiners.

Statistical analysis

All the data collected from 104 patients by six examiners have been presented. Data is represented in percentages in accordance with the aims of our study. The results of all the groups have been mentioned in percentages for simplicity of data presentation and understanding.

RESULTS

A total of 104 patients (61 males and 43 females) with an age range of 14–60 years (mean age of 34.175 years) were examined. A total of 1171 cases of the recession were scored in 104 patients. 1089 cases out of 1171 cases were included in the study. Eighty-two cases were excluded at the time of interpretation of the data. Table 2 provides the details of the demographic data and number of recession cases recorded by each examiner.

Table 2

Distribution of recession cases on the basis of demographic data by the examiners

Of 1089 recession cases, a total of 458 cases (42.05%) were recorded in the maxillary arch and 631 cases (57.94%) were recorded in the mandibular arch. Tables 3 and 4 provide the details of the recession cases recorded on the basis of the arch (maxillary/mandibular) and tooth type (incisors/canines/premolars/molars) by each examiner. The incisors accounted for 39.76% (433), canines 14.04% (153), premolars 23.78% (259), and molars 22.40% (244) of recession cases.

Table 3

Arch and tooth wise distribution of recession cases

Table 4

Percentage distribution of recession cases on the basis of arch and tooth type

Table 5 provides the details of applicability of Miller's classification. 377 out of 1089 (34.61%) cases of the recession could be classified by Miller's classification. The data collected by examiners in respect of Miller's classification has been segregated into completely classified cases and incompletely classified cases. Complete application of Miller's classification included those cases that had only buccal recession confirming to Miller's criteria. The incompletely classified cases were those, which had both buccal and lingual/palatal recessions but only buccal recessions (confirming to Miller's criteria) could be classified and included in this data (as Miller's classification does not include palatal/lingual recession). Complete application of Miller's criteria was possible in 208 cases (19.10%), and 169 cases were incompletely classified (15.51%). The number of cases in each category of Miller's classification has been detailed in Table 5. Buccal recession cases, which did not confirm to Miller's criteria, e.g., cases with interdental bone loss with the buccal recession not extending up to MGJ, were not categorized in this group.

Table 5

Details of applicability of Miller's classification

The data collected for each of the 1089 cases were also categorized on the basis of surfaces involved, details of which are presented in Table 6. Each tooth with the recession was considered as one entity. The cases with only buccal recessions were categorized under buccal (B), only palatal recessions under palatal (P) category and only lingual recessions under lingual (L) category. The cases having marginal recessions on buccal and palatal aspect with/without IDP involvement were categorized under buccal and palatal category and cases with marginal recessions on buccal and lingual aspect with/without IDP involvement were categorized under buccal and lingual category. IDP recessions had no marginal recession component either on buccal or palatal/lingual aspect. Recessions with IDP involvement and only P/L marginal recession were categorized under IDP with marginal P/L recessions. Recessions with IDP involvement and B marginal recession were categorized under IDP with marginal B recessions.

Table 6

Details of recession cases on the basis of surfaces involved

All the 1171 cases were classified by Kumar and Masamatti's classification. Table 7 gives the details of the applicability of this classification in 1089 cases of gingival recession. The table also provides the percentage of cases recorded in each class and its sub-class. It was observed that maximum number of cases belonged to Class II category (48.32%) of Kumar and Masamatti's classification. The subclass II B had maximum recordings (29.75%).

Table 7

Details of applicability of Kumar and Masamatti's classification

DISCUSSION

Gingival recession is one of the most common disease entities encountered in daily practice. It is important that all the cases of gingival recession get recorded and classified at the time of case-history recording to arrive at a correct diagnosis. Classification systems provide a scaffold for the study of diseases in an organized fashion.[2] A classification system immensely helps in easy chronicling and communication among the clinicians and patients. Classification systems help in establishing the health care needs of the patients. Inability to classify all recession defects can lead to inaccurate diagnosis and treatment planning.[3]

The gingival recession has been frequently classified using Miller's classification system.[7] From the time of its introduction in 1985, Miller's classification has been used by most of the clinicians as a “bench-mark” to classify gingival recession. Miller's classification has been exclusively applied on labial/buccal aspects of teeth.

In the recent past, authors have reassessed the applicability of Miller's classification system.[3912] Miller's classification was based on two criteria: Diagnosis and prognosis.[12] The limitations of Miller's system and inability to classify certain defects have been highlighted.[391012] The limitations of Miller's classification result in the insufficient depiction of the clinical condition.[3] Furthermore, all the recession cases cannot be classified using Miller's system.[312] Pini-Prato in 2011 suggested “careful evaluation of the noncritical and widespread use of the Miller classification”.[12] It was suggested to devise new classification systems of the gingival recession on the basis of the “characteristics of taxonomy and scientific evidence.”[12]

Kumar and Masamatti proposed a new classification system to overcome the limitations of the Miller's classification 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.[3]

A total of 1171 recessions were recorded in 104 patients by 6 examiners. Both the classification systems (according to the defined criteria of each system) were applied on each case recorded. Although all the cases recorded (1171) were categorized on the basis of Kumar and Masamatti's criteria,[3] only 1089 cases were included in the study. Eighty-two cases were excluded during the interpretation of results. It was observed that all the cases in a clinical setting couldn’t be categorized by Miller's criteria.

The Class I-A (F) of new classification and Miller's Class I, Class I-B (F) and Miller's Class II, Class II-C (F) and Miller's Class III, Class III-B (F) and Miller's Class IV are similar. The results obtained for these categories are same by both classification systems. Very few typical Miller's Class II, III, and IV were observed in our study. This finding is interesting as well as important. There were few cases, which actually extended up to MGJ with or without IDP loss. Hence, in majority of subjects, the recessions which were observed, remained coronal to MGJ with or without IDP loss. All the cases having P/L recession could not be classified according to Miller's criteria.

Maximum numbers of cases were recorded under Class II of the new classification. In Class II, the tip of the IDP is located between the interdental contact point and the level of the CEJ midbuccally/mid-lingually. Class II-A deals only with IDP recession. Class II-B deals with IDP recession with gingival margin on F/L aspect lies apical to CEJ but coronal to MGJ with attached gingiva present between the marginal gingiva and MGJ. Hence, the cases with either IDP recession only or IDP recession with marginal tissue recession coronal to MGJ form a substantial group that remained uncategorized by Miller's criteria.

Another frequently observed gingival recession was Class III-A (according to new classification). Class III-A deals with cases where the tip of the IDP is located at or apical to the level of the CEJ mid-buccally/mid-lingually, and marginal tissue recession is coronal to MGJ. This category of recession has a severe interproximal bone loss, but the marginal recession is coronal to MGJ. Miller has not defined any such criteria where cases of severe interproximal loss and marginal recession coronal to MGJ could be classified. This category also remained uncategorized by Miller's criteria.

Another important aspect of the new classification is that IDP position is defined in each category of classification. Hence, all the cases belonging to Class II will have the tip of IDP located between the interdental contact point and the level of the CEJ midbuccally/mid-lingually and Class III cases have the tip of IDP located at or apical to the level of the CEJ mid-buccally/mid-lingually. This categorization presents the approximate severity of the condition in the classification itself. Cases with open contacts where IDP was nonexistent, the position of the crest of gingiva in the interdental region was used to distinguish between Class I, II, and III. Furthermore, the cases having only IDP loss can also be categorized by this new classification and need of another classification gets minimized.

In our study, we found 1912 sites of recession in 1089 teeth. We calculated the IDP loss as buccal and lingual or buccal or palatal. Also cases having IDP loss with the marginal loss only on one aspect (either buccal or lingual/palatal) were marked for IDP loss on both the aspects. This exaggerates the recession count in Class II-A. The cases with IDP loss can be considered as one entity (without splitting the cases into buccal and lingual). Cases demonstrating IDP loss with marginal tissue loss on either buccal or palatal/lingual side can also be considered as one category and categorized on the basis of IDP and marginal tissue level. As this is probably the first study, where the applicability of two classification systems has been compared, we recorded each IDP case separately into buccal and palatal/lingual category. The recording of IDP separately as buccal and palatal/lingual is one major limitation of our study. This has exaggerated the count in Class II-A. Considering IDP loss on only one aspect, the total no of cases in Class II-A would be 69 and would have reduced number of sites of recession from 1912 to 1653.

Another observation of substantial interest was the number of cases with both B and P/L (51.33%) recession. This confirms the fact that most of the cases of recession have P/L component that remains uncategorized in Miller's classification.

The prevalence of recession was more in mandibular teeth in our study. The results are similar to the study conducted by Vehkalahti and Wilson.[1314] In our study, the maximum recession was observed in mandibular anterior teeth, as was mentioned by Albander and Kingman.[15] It was also observed that incisors as tooth type demonstrated more recession as compared to other tooth types. At the site level, the buccal recessions had a higher rate of prevalence than lingual/palatal recession. The results of our study are in confirmation with study by Albander and Kingman.[15]

Eighty-two cases recorded by examiners were excluded from the study at the time of data interpretation. The examiners had categorized these cases on the basis of Kumar and Masamatti's classification.[3] But none of these excluded cases could be categorized on the basis of Miller's criteria.[7] The cases were excluded because of the difference in the levels of papilla observed on buccal and palatal/lingual aspects. This difference of level of IDP prohibited the categorization of these cases on the basis of the level of IDP. All the examiners had categorized buccal and palatal/lingual recessions into different groups on the basis of the level of buccal and palatal/lingual papilla. The level of more apical papilla determines the category. Radiographic evidence, although not used in our study, would have helped in such cases. This fact was not discussed before the start of the study, as we did not encounter any such case in our prestudy period. Hence, all such cases were excluded from the study.

CONCLUSION

This study suggests that the Kumar and Masamatti's classification system may be used to classify gingival recession defects, so that the cases, which cannot be categorized on the basis of Miller's classification, also find their relevant place.