Modified extrinsic tooth stain index and its clinical applicability

Abstract

Aim:

The first index for the assessment of extrinsic stain was published by Lobene in 1986. Using the Lobene stain index in the field is very cumbersome as well it does not meet the general requirement of an index, i.e., the index is to be simple, rapid, highly reproducible, and sensitive enough to detect small changes in the staining level. Hence, there was a need to develop an alternative index for the same purpose. Hence, the only present study was undertaken to propose a modified stain index with more simplicity and clarity.

Materials and Methods:

An observational study was carried out among 16–44-year-old participants who had at least six natural teeth and were generally healthy. For the revised index, the criteria and codes for intensity were kept the same as MacPherson Index but the criteria for recording area were modified. The data scoring for each tooth was mentioned in the proposed table and was recorded for each of the surfaces according to the proposed area and intensity codes. Analysis was carried out using SPSS version 21 (IBM, Inc. Virginia, United States). Inferential statistics were performed using the Mann–Whitney U-test. Nonparametric tests were applied following the imposition of a numerical interval scale the same as the Lobene index.

Results:

No statistically significant difference was appreciated for the area, intensity, and product of area × intensity when compared for measurements recorded by two indices as P > 0.05. Hence, validating the proposed index for the clinical application.

Conclusion:

The proposed modified index may be advantageous over its conventional counterpart due to its ease of recording and concise scoring and also less complexity in the area to be recorded.

INTRODUCTION

Esthetics dentistry is a boon to humankind, where a beast can be turned into a beauty. In our modern competitive society, a pleasing appearance often means the difference between success and failure in both our personal and professional lives.[1] There is globalization and modernization in the growing population of the world. Men and women are very conscious about their appearance. The present generation is giving importance to their esthetics in every aspect to improve their personality. Due to the advancement in dentistry, people are eager to know about how dentistry would help in enhancing their smiles. Esthetic or cosmetic dentistry strives to merge beauty and function with the values and individual needs of every patient. Esthetics is not only concerned with smile correction but also with how pleasing the smile is and definitively smile will look good if it is free of all types of stains, namely, intrinsic or extrinsic.[2]

Extrinsic dental staining is considered a major cosmetic problem for many people who would prefer whiter teeth.[3] This problem is reflected in the numerous whitening oral hygiene product now available for use by the public at large. The efficacy of these products may be evaluated both in vitro and in vivo using a stain model. In vitro assessment can be done numerically using a spectrophotometer, whereas in vivo assessment requires subjective assessment by a dental examiner usually employing a recognized stain index.[4]

The first index for the assessment of extrinsic stain was published by Lobene in 1968.[5] This involved evaluating the extent and intensity of stains on the gingival and body regions of the labial surface of incisor teeth. Using the Lobene stain index[5] in the field is very cumbersome as well it does not meet the general requirement of an index, i.e., the index is to be simple, rapid, highly reproducible, and sensitive enough to detect small changes in the staining level. Hence, there was a need to develop an alternative index for the same purpose. Macpherson et al.[6] in the year 2000 proposed a modified version of the Lobene stain index.[5] This involved visual stain assessment of the buccal/labial and lingual/palatal aspects of the index teeth (only incisors). The modification consisted of dividing each aspect into four separate sites instead of only two, i.e., gingival, a body of the tooth, mesial, and distal.[6] However, then again, this index was also difficult to perform in a clinical field; thus, there was a need for one modified stain recording index which could solve the problem seen with pioneer indices. Hence, the only present study was undertaken to propose a modified stain index with more simplicity and clarity. Differences between the MacPherson index and the modified stain index [Table 1].

Table 1.

Differences between Macpherson Index and modified stain index

MacPherson index	Modified stain index
The tooth surface was divided into gingival, body, mesial, and distal parts	In this index, the tooth surface was divided into three equal horizontal parts, i.e., incisal, middle, and cervical/gingival third on both the buccal and lingual surface
Only maxillary and mandibular central and lateral incisors were evaluated	Along with maxillary and mandibular central and lateral incisors, canines were also evaluated increasing the sensitivity of the index

MATERIALS AND METHODS

Ethical approval was sought from the institutional ethical committee from SRCDSR, Faridabad (SRCDSR, Faridabad [SRCDSR/ACAD/2021/10131-A]). This index has been formulated, following approval from the dental ethics committee, to allow easy calculation of stain intensity and thereby frame appropriate treatment according to the patient’s needs. It is a modification of the MacPherson stain index which was devised to challenge the conventional Lobene stain index which consisted of 412 labial and 422 squares on the lingual surface.

As compared to the MacPherson stain index where a tooth surface was divided into four separate sites (gingival, body, mesial, and distal), the index teeth in the proposed index were divided into three equal horizontal parts, namely, incisal, middle, and cervical/gingival third, both on the labial and lingual surface [Figure 1].

Figure 1.

Intensity of extrinsic stains. C – Cervical, M – Middle, I – Incisal

All the anterior teeth were regarded as index teeth (11,12,13,21,22,23,31,32,33,41,42, and 43). Before the assessment of stains, the examiner instructed the participants to brush their teeth and rinse with water to remove any plaque and food debris, and then the teeth were dried using a chairside two-way syringe and an effort was made to keep them dry throughout the examination.

Inclusion and exclusion criteria

A total of 100 subjects aged from 16 to 44 years who had six healthy natural teeth and were generally healthy, were included in the study. Only healthy natural tooth surfaces and extrinsic stains were taken into account, for example, coffee or tobacco stains, stains due to irregular tooth surfaces, etc., Stains adjacent to or as a result of restorations, injury, or any other intrinsic cause were excluded. The tooth with any crown, restoration, and fractures was also excluded. All participants who had any history of oral prophylaxis in the past 6 months were also excluded.

Stain assessment

Stain evaluations were performed by two examiners wherein, one of them recorded MacPherson modified stain index, whereas the other recorded the revised modified proposed index. The assessment was made with the naked eye.

For the revised index, the criteria and codes for intensity were kept the same as MacPherson Index but the criteria for recording area were modified.

Scores for stains [Figure 1]

• 0 – No stain present, natural tooth coloration

• a – Faint stain (barely visible light stain/off-white to light yellow)

• b – Clearly visible stain, orange to brown

• c – Dark stain, deep brown to black.

Scores for the area covered:

1. Stains cover only one-third of the surface either partially or completely (incisal, middle, and gingival)

2. Stains cover two-thirds of the surface either partially or completely (incisal + middle/incisal + cervical/cervical + middle/cervical + incisal)

3. Stains cover all three horizontal sections of the teeth partially or completely [Figure 2].

Figure 2.

Area covered by extrinsic stains. a – Faint stain (barely visible light stain/off-white to light yellow), b – Clearly visible stain, orange to brown, c – Dark stain, deep brown to black.

After obtaining the area and intensity of the extrinsic stain coring the tooth a product score was calculated (I * A) and compared. Two examiners independently examined extrinsic stains intensity and the area covered. The result was a total of 22 recorded readings. The interexaminer differences were presented in 95% confidence intervals. The interclass correlation coefficient was used to assess the agreement between pairs of examiners. One of the examiners re-examined the same 22 subjects at a 1-week interval. This process was assessed in the same manner as interexaminer reliability outlined previously.

Data analysis

The data scoring for each tooth was mentioned in the proposed table and was recorded for each of the surfaces according to the area and intensity codes. Thereafter, the product of area and intensity was calculated only for the tooth that had the highest intensity of staining on its surface. If more than one tooth had the same intensity, the tooth which covered a greater area was considered to calculate the product. Subsequently, the interexaminer and intraexaminer correlation coefficients were calculated to assess the reliability of the revised index. Analysis was carried out using SPSS version 21 (IBM, Inc. Virginia, United States). Inferential statistics were performed using the Mann–Whitney U-test. Nonparametric tests were applied following the imposition of a numerical interval scale the same as the Lobene index. The level of significance was set at P < 0.05.

RESULTS

The training was done on patients reporting as an outpatient to the department of public health dentistry at one of the reputed dental institutions of North India. The examiner was trained under the guidance of a professional having previous experience in recording such indices to limit inter and intraexaminer variability. The training continued till the examiner started producing consistent observations.

The value of the interclass correlation coefficient for the agreement between examiner I and II was 0.89 which is significantly different from zero (P = 0.001) indicating high agreement. The value of the interclass correlation coefficient for examiner I versus I was 0.87 (P 0.001). This result also means that a high degree of agreement has been achieved at different times by the same examiner [Table 2]. Surface area, intensity, and product of area and intensity covered by extrinsic stains were calculated and compared between two indices, i.e., one recorded by the proposed index and one with MacPherson’s Index. No statistically significant difference was appreciated for the area, intensity, and product of area × intensity when compared for measurements recorded by two indices as P > 0.05 [Table 3]. Hence, validating the proposed index for the clinical application. Furthermore, the time taken to assess the extrinsic stain was found to be lesser when the assessment was made using a proposed index.

Table 2.

Inter and intraexaminer reliability

	Reliability	Mean difference	95% CI for the difference
Interclass coefficient (examiner I vs. II)	0.89	0.010	0.050-0.004
Intraclass coefficient (examiner I vs. I)	0.87	0.005	0.038-0.017

CI - Confidence interval

Table 3.

Comparison of modified and MacPherson index

	Mean	SD	SEM	P
Area covered
Proposed index	2.0379	0.46752	0.04699	0.382 (NS)
MacPherson index	2.0152	0.46678	0.04691
Intensity
Proposed index	2.1061	0.29686	0.02984	0.058 (NS)
MacPherson index	2.27	0.843	0.085
Area × intensity
Proposed index	4.4189	1.34496	0.13517	0.413 (NS)
MacPherson index	4.5657	2.00751	0.20176

P - Probability value; SD - Standard deviation; NS - Statistically not significant; SEM - Standard error mean

DISCUSSION

Dental stains included in this study represented the population with moderate-to-heavy stains, resulting in a greater scattering of the data. Since nonsignificant differences between the two study indices made it more possible of accepting this newly proposed index to measure extrinsic stains as it follows all the properties index should have as stated by Davies.[7]

Stain assessment in the present study was done both on lingual as well as buccal surfaces yet from an esthetic perspective it is of more importance on buccal surfaces. In the previous studies, no association was observed between variability in diet and stains; hence, dietary factors were not evaluated in the present study.

Despite a thorough literature search, we could not find any easy tool to assess the extent and intensity of measuring extrinsic stains on teeth. The Lobene Index[5] and MacPherson Index[6] were the only two indices found in the literature to measure extrinsic stains. Hence, there the need was raised for a simple, valid, quantifiable, reliable, and clear index which was also our aim.

Management of extrinsic stains

Extrinsic staining caused by foods, beverages, or adverse behavioral habits such as smoking, chewing tobacco, coffee, and tea is treated with thorough dental prophylaxis. Cessation of dietary or other contributory habits to prevent further staining is advised to prevent stating.[8] Most dentifrices contain an abrasive, detergent, and anti-tartar agent. Effective tooth brushing twice a day with a dentifrice helps to prevent extrinsic staining. Few cosmetic kinds of toothpaste, containing titanium dioxide, cover extrinsic stains like paint covering a wall and do not change the internal tooth color and hence are recommended for maintaining oral hygiene.[9] In severe cases of extrinsic tooth staining which cannot be managed by regular professional prophylaxis and treatments in those cases, bleaching, laminates, and veneers turn out to be a good option.

Limitations

There was no research comes without limitation. The sample size recruited in this study was small limiting the generalizability of the proposed index. Second, related dietary factors were not assessed in the present study which may also lead to confounding bias. Hence, further research with a larger sample size and matching of dietary factors are needed to extrapolate the results.

CONCLUSION

The proposed modified index may be advantageous over its conventional counterpart due to its ease of recording and concise scoring and also less complexity in the area to be recorded. As the tooth surface was divided into three equal parts on both the lingual and labial sides as compared to the conventional index in which the tooth surface was divided into four parts; hence, it becomes comparatively easy to measure the intensity and area covered with the proposed extrinsic stain. It showed a lesser coefficient of variation, thus presenting higher discriminatory power. Further studies with a larger sample size are required to exhibit its generalizability in the clinical field.

Clinical relevance

Scientific rationale for study

To date, no simple index is documented in the literature to report extrinsic stains. Already documented indices were cumbersome to record. Hence, there was a need for one simplified index to record the intensity of extrinsic stains on teeth.

Principal findings

The new proposed index was found to be valid when compared to the previously documented index.

Practical implications

The proposed index is easier and less time-consuming and hence can be used in clinical settings with much ease for planning the respective treatment for extrinsic stains.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.