Comparative evaluation of oral hygiene status by using oral ... : Journal of Indian Society of Periodontology (2025)

INTRODUCTION

The importance of good oral hygiene has been recognized for centuries. Over time, its significance has been more clearly defined, addressed, and practiced. Good oral hygiene is a crucial indicator of overall oral health, with a strong association between oral health and general health [Figure 1]. Therefore, a more precise oral hygiene assessment is necessary.

Indeed, dentistry has long needed the development of a simple but accurate quantitative method for assessing oral cleanliness. Such an index would provide a standardized approach for evaluating and measuring oral hygiene, reduce inter-examiner variability, and allow for more accurate comparisons across clinical practices and epidemiological research studies.

Numerous investigators have proposed and utilized various methods for assessing oral hygiene status in population groups.^[1–3]

Greene and Vermillion^[4] introduced the Oral Hygiene Index (OHI) to evaluate oral hygiene status. This index assesses 12 surfaces across the complete dentition, divided into six segments to score debris and calculus. The OHI has been suggested as a useful epidemiological tool for quantitatively assessing the oral hygiene status of individuals or groups.

In 1964, Greene and Vermillion^[5] revised the OHI into the Simplified Oral Hygiene Index (OHI-S), which evaluates only six surfaces of six index teeth – four posteriors and two anteriors. It is recommended for use in epidemiological research on periodontal diseases. The OHI-S is simpler but less sensitive than the original OHI.

InIn 1967, Greene^[6] found that the OHI and OHI-S are effective clinical assessment tools applicable to various studies. Variations of these indices are more useful for research requiring more detailed or precise evaluations of oral hygiene.

Garg,^[7] in 1987, introduced the Modified Oral Hygiene Index (OHI-M), in which a special attention is given to recording oral debris and calculus, particularly on the occlusal surfaces [Figure 2] of each fully erupted permanent tooth. It was found that carries and related lesions were the primary causes of unilateral mastication, with individuals avoiding chewing on the affected side. In 20% of cases of unilateral mastication, gingival and periodontal lesions were observed. In addition, the deposition of calculus, gingival inflammation, and pocket depth increased with the duration of unilateral mastication, and the destruction of the attachment apparatus was directly proportional to its duration.

The OHI-M demonstrated good reproducibility, reliability, objectivity, sensitivity, and simplicity in scoring debris, stains, and calculus. These attributes make it a valuable tool for accurately assessing oral hygiene status.

A comparative evaluation of oral hygiene status has been conducted, considering the advantages and limitations of three indices: OHI, OHI-S, and OHI-M.

MATERIALS AND METHODS

Approval for the study was obtained from the institutional ethical committee. Patients were randomly selected (using simple random sampling) from those referred to the department of periodontology for periodontal treatment. 221 patients (119 males and 102 females) participated, with ages ranging from 16 to 58 years (mean age, 37 years), and all participants had at least 20 natural teeth. The purpose of the study was explained to the participants, and verbal informed consent was obtained. Scoring for all three indices was conducted by a single investigator. The sample size was calculated based on a 95% confidence level. As per the study design, the following three indices were used to evaluate oral hygiene status:

Oral hygiene index

The scoring method of OHI is based on the combined debris index and calculus index. Each index evaluates the amounts of debris or calculus on the buccal and lingual surfaces of the teeth separately in three segments of each dental arch. The amount of debris or calculus is quantified using a 4-point scale (0, 1, 2, 3) with an appropriate score assigned to each surface based on the accumulation level [Figures 3 and 4].

Debris was evaluated by running the side of a No. 23 (Shepard’s Crook) explorer along the surface, while the amount of calculus present was recorded through visual examination.

Simplified oral hygiene index^[5]

The scoring method for evaluating oral hygiene status involves assessing 6 surfaces of six index teeth – four posterior and two anterior teeth.

The scoring criteria for oral debris and oral calculus are the same as those used in the OHI.

Modified oral hygiene index^[7]

The scoring method for the OHI-M consists of the combined Modified Debris Index (DI-M) and Modified Calculus Index (CI-M). These indices are scored by evaluating facial (buccal/labial), oral (palatal/lingual), and specifically occlusal surfaces of each fully erupted permanent tooth.

The scoring sequence for debris and calculus in the OHI-M begins with facial (buccal/labial) surfaces, followed by oral (palatal/lingual) surfaces, and concludes with the occlusal surfaces. Scoring starts in the upper right posterior segment, proceeds to the upper anterior teeth, and then to the upper left posterior segment. In the lower arch, the sequence is similar but progresses from left to right, as described by Greene and Vermillion^[4] [Figure 5]. The occlusal surfaces are scored last in the sequence [Figure 6].

The scores and criteria for oral debris on facial (buccal/labial) or oral (palatal/lingual) surfaces are as follows:

1. Score 0: No debris or stains present
2. Score 1: Soft debris covering no more than one-third of the tooth surface or the presence of extrinsic stains without other debris, regardless of the surface area covered
3. Score 2: Soft debris covering more than one-third but not more than two-thirds of the exposed tooth surface
4. Score 3: Soft debris covering more than two-thirds of the exposed tooth surface.

The following scores and criteria apply to oral debris on occlusal surfaces:

1. Score 0: No debris or stains present
2. Score 1: Soft debris covering no more than one-third of the occlusal surface of the tooth being examined, or soft debris present in the pit and fissure areas, or extrinsic stains present without other debris, regardless of the surface area covered
3. Score 2: Soft debris covering more than one-third but not more than two-thirds of the occlusal surface of the tooth
4. Score 3: Soft debris covering more than two-thirds of the occlusal surface of the tooth.

The scores and criteria for calculus on facial (buccal/labial) or oral (palatal/lingual) surfaces are as follows:

1. Score 0: No calculus present
2. Score 1: Supragingival calculus covering no more than one-third of the exposed tooth surface
3. Score 2: Supragingival calculus covering more than one-third but not more than two-thirds of the exposed tooth surface, or individual flecks of subgingival calculus around the cervical portion of the tooth, or both
4. Score 3: Supragingival calculus covering more than two-thirds of the exposed tooth surface, or a continuous heavy band of subgingival calculus around the cervical portion of the tooth, or both.

The scores and criteria for calculus on occlusal surfaces are as follows:

1. Score 0: No calculus present on the occlusal surface of the tooth
2. Score 1: Calculus covering no more than one-third of the occlusal surface of the tooth, or calculus presents only in the pits and fissures of the occlusal surface [Figure 7]


3. Score 2: Calculus covering more than one-third but not more than two-thirds of the occlusal surface of the tooth [Figure 8]


4. Score 3: Calculus covering more than two-thirds of the occlusal surface of the tooth [Figure 9].

Garg, the author of OHI-M,^[7] clarified and presented scoring criteria in this study using pictorial representations [Figures 7-9], clinical photographs [Figure 10a and b], and a pro forma for recording DI-M and CI-M scores for debris and calculus [Figure 11]. The advantage of this pro forma is that it allows for calculating all three indices – OHI, OHI-S, and OHI-M, either simultaneously within the same timeframe or individually. For recording OHI-S scores, the indexed teeth are highlighted [Figure 11]. Figure 12 illustrates the scoring of OHI-M and the calculation of the average score for an individual or a group of individuals.

Statistical analysis

The collected data were entered into a Microsoft Excel spreadsheet and analyzed using IBM SPSS Statistics, Version 22 (Armonk, NY, USA: IBM Corp). Descriptive data were presented as frequencies, percentages, means, and standard deviations. Pearson’s correlation test was applied to examine correlations between OHI, OHI-S, and OHI-M scores. Simple linear regression was used to construct a model to predict OHI and OHI-S scores based on OHI-M scores. A P < 0.05 was considered statistically significant.

RESULTS

All 221 participants were analyzed together. 69 participants (31.22%) had debris/extrinsic stains, while only 24 participants (10.86%) had calculus on their occlusal surfaces.

The mean OHI-M scores were found to be lower than the scores for both OHI and OHI-S. Table 1 presents the mean values, standard deviations, and ranges (minimum and maximum values) for all three indices: OHI, OHI-S, and OHI-M. The mean and standard deviation of the OHI-M were found to be the lowest (2.55 ± 0.82) compared to the OHI (7.13 ± 1.79) and OHI-S (3.23 ± 0.99). The range (minimum-maximum) for OHI scores was 3.16–11.66; for OHI-S, it was 1.00–5.66; and for OHI-M, it was 0.86–5.56. These findings indicate less variability in OHI-M scores compared to OHI and OHI-S.

The correlation coefficients among the three indices (OHI, OHI-S, and OHI-M) indicate positive correlations, as shown in Table 2. A strong correlation was observed between OHI and OHI-S (r = 0.85), OHI and OHI-M (r = 0.86), and OHI-S and OHI-M (r = 0.82). In addition, there were strong correlations between Debris (scored by the OHI) and Debris-S (scored by the OHI-S) (r = 0.74), Debris and Debris-M (scored by the DI-M) (r = 0.75), and Debris-S and Debris-M (r = 0.76). Similarly, strong correlations were noted between Calculus (scored by the OHI) and Calculus-S (scored by the OHI-S) (r = 0.82), Calculus and Calculus-M (scored by the CI-M) (r = 0.82), and Calculus-S and Calculus-M (r = 0.74).

Table 3 summarizes the results of a simple linear regression analysis predicting OHI scores based on OHI-M scores. The study shows that OHI-M is a significant predictor of OHI (P < 0.001), with an R² = 0.75. The regression model indicates that each unit increase in the OHI-M score corresponds to an estimated increase of 1.88 units in the OHI score (F [1, 220] = 645.45).

Table 4 presents the results of a simple linear regression analysis predicting OHI-S scores based on OHI-M scores. The study indicates that OHI-M is a significant predictor of OHI-S (P < 0.001), with an R² = 0.68. According to the regression model, each unit increase in the OHI-M score corresponds to an estimated increase of 0.99 units in the OHI-S score (F [1, 220] = 464.35).

These findings, supported by the graphical representations in Graphs 1 and 2, confirm the strong predictive relationships between OHI-M and both OHI and OHI-S, demonstrating positive linear correlations.

DISCUSSION

The results reveal that OHI-M is the most sensitive method, compared to OHI and OHI-S, for evaluating oral hygiene status in individuals or groups.

Greene and Vermillion developed the OHI in 1960^[4] and OHI-S in 1964^[5] to assess population-level oral hygiene when no other quantitative method was available. In the original OHI, only 12 surfaces from six segments of the dentition were considered to record oral debris and calculus. Greene and Vermillion described the OHI as a sensitive, simple, and helpful tool for assessing oral hygiene status quantitatively for both individuals and groups. However, they only evaluated 12 surfaces to represent the complete dentition.

In 1964, Greene and Vermillion^[5] simplified the OHI to OHI-S. This index used specific surfaces of six index teeth – four posterior and two anterior teeth. Only the labial surfaces of the upper right central incisor and lower left central incisor were included for the anterior teeth, though calculus is often more prevalent on the lingual surfaces of lower anterior teeth. The small number of specific surfaces selected and assessed reduces the sensitivity of OHI-S.

OHI and OHI-S were initially developed to assess oral cleanliness in population studies rather than to provide comprehensive oral hygiene assessments. Greene and Vermillion noted that it was neither necessary nor feasible to evaluate all debris and calculus present in an individual’s mouth, instead suggesting that partial data could represent overall oral hygiene. They found that OHI-S is less sensitive than OHI, yet both are sufficiently sensitive for assessing oral hygiene in population studies. However, the term “sufficiently sensitive” lacks precision, reducing reliability in producing accurate results. Moreover, the developers of OHI and OHI-S acknowledged that the rapid recording of scores outweighed precise accuracy for assessing individual oral hygiene.

The absence of specific scoring for debris/stains and calculus on occlusal surfaces – areas where these deposits are commonly present – further restricts the ability of the OHI and OHI-S to provide a comprehensive and accurate oral hygiene assessment. Examining only 12 surfaces in the OHI or 6 surfaces of six indexed teeth in the OHI-S, while excluding occlusal surfaces, specifically, does not fully represent an individual’s oral hygiene status.

Greene and Vermillion^[5] also tested an “all surfaces method” alongside the 6 surfaces (OHI-S) and 12 surfaces (OHI) methods, concluding that “all surfaces” provided lower mean scores for individuals than the limited-surface approaches. This result is consistent with the current study’s findings, which showed that the mean OHI-M scores were lower than those of OHI and OHI-S, a finding that is similar to Greene and Vermillion’s 1964 findings. However, their “all surfaces method” needed more precise definitions and specific scoring for debris/stains and calculus on occlusal surfaces, where these deposits are frequently found.

In 1967, Greene^[6] mentioned that while OHI and OHI-S serve as effective tools for clinical assessments and various studies, different variations of these indices could benefit studies requiring more detailed or precise evaluations of oral hygiene. This observation underlines the importance of using a scoring system that provides an accurate and comprehensive assessment across the entire dentition, limiting OHI and OHI-S in clinical, epidemiological, and research applications. However, their variant method demonstrates limitations in scoring debris/stains and calculus on occlusal surfaces, where these deposits are common.

In 1987, Garg^[7] introduced the OHI-M to study unilateral mastication and periodontal health. This modified index proved a reliable and sensitive method for assessing debris/stains and calculus, especially on occlusal surfaces, as specific scoring criteria were assigned to evaluate deposits on these surfaces.

The results of the present study reveal that OHI-M is the most sensitive scoring method compared to OHI and OHI-S for evaluating oral hygiene status. OHI-M addresses the limitations and shortcomings of both OHI and OHI-S. While the scoring and calculation process in OHI-M requires slightly more time, this is compensated by its accuracy and thorough assessment, making it a valuable tool. Therefore, the accuracy of the outcomes justifies overlooking the minor time factor. These results support the credibility and utility of OHI-M in clinical and epidemiological studies, such as evaluating toothbrush efficiency, brushing methods, dentifrices, anti-tartar and anti-plaque agents, dental health practices, long-term effects of dental health education programs, and more.

This study further clarifies OHI-M using a pictorial representation of the OHI-M scoring sequences [Figures 5 and 6], the CI-M scoring criteria [Figures 7-9], a pro forma for recording debris and calculus using DI-M and CI-M [Figure 11], and a simplified calculation method [Figure 12]. These illustrations improve the clarity and validity of OHI-M, reinforcing its effectiveness and revalidating its use.

The study concludes that OHI-M is the most sensitive method for evaluating oral hygiene status compared to OHI and OHI-S, with its validity reaffirmed. Garg, the author of OHI-M,^[7] also suggests a variant of OHI-M as the “16 surfaces method” by evaluating only six teeth: four first molars (by scoring buccal, lingual, and occlusal surfaces) and two incisors– upper right central incisor and lower left central incisor (by scoring labial and lingual surfaces). The same pro forma of OHI-M can be used [Figure 11]. This variant involves a total of 16 specific surfaces, compared to only 12 surfaces in OHI and 6 surfaces in OHI-S, where occlusal surfaces are not specifically assessed. This variant may be helpful in large-scale epidemiological studies and research where rapid data collection is demanded. However, OHI-M is the most accurate for evaluating oral hygiene status.

CONCLUSION

The OHI, OHI-S, and OHI-M showed positive correlations. The OHI-M is found to be the most sensitive scoring method for evaluating oral hygiene status compared to the OHI and OHI-S. These results further confirm the validity of the OHI-M.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

REFERENCES