The Design, Development, and Calibration of Cervical Abrasion Index of Treatment Needs Probe for Measurement of Cervical Abrasion

Abstract

Context:

Although a common dental problem, there are no simple instruments or reliable methods to measure cervical abrasion.

Aim:

To study the design, development, calibration, efficacy, and compliance of usage of a novel Cervical Abrasion Index of Treatment Need (CAITN) probe to measure cervical abrasion.

Settings and Design:

The ex-vivo study was conducted as a part of comprehensive study for the development of standardized CAITN probe and index with a standard methodology for recording the abrasion.

Materials and Methods:

The compliance and usage of the probe were assessed by a standardized set of questionnaires to the interns followed by an ex-vivo study in 100 subjects. Gold standard comparisons with Vernier caliper, inter-examiner, and intra-examiner reliability were analyzed using SPSS.

Results:

Data from the questionnaire indicate that 100% of examiners had no difficulty in handling the instrument or measuring and reading the values. Comparison between the CAITN probe and the gold standard was statistically significant indicating a correlation for cervical abrasion measurement between the two methods (p < 0.001). The mean difference between the two measurements using the CAITN probe and gold standard method was calculated with paired t-test and was insignificant (p > 0.05). High statistical significant correlation was also found for intra-examiner and inter-examiner reliability measurement of CAITN probe (p < 0.001).

Conclusion:

The design and structure of the CAITN probe are standardized with a fair gold standard comparison and that the novel probe can be used as an effective tool to measure the depth of cervical abrasion and its treatment needs.

INTRODUCTION

Cervical abrasion is often related to abnormal mechanical processes that may or may not be linked to mastication.[1] Several biological, chemical, and behavioral functions can hasten the process leading to structural and functional loss of teeth. The cementum and dentin are more likely to be severely affected.[2] These are a group of lesions called noncarious cervical lesions presented as a wedge or V-shaped defect on the cervical region of the tooth, associated with gingival recession.[3,4] The multifactorial nature of these lesions is due to variability in pathogeneses and individual tooth characteristics.[3,5,6] Eccles suggested the term “tooth surface loss” when a single etiological factor was difficult to identify. However, Smith and Knight advocated the term “tooth-wear” to embrace all three processes of abrasion, attrition, and erosion.[7,8]

Although many tooth-wear indices have been developed for use, they lack standardization and uniformity of data[9,10,11,12] interfering with proper evaluation of therapeutic, and prevention measures. Smith and Knight developed a comprehensive index using models, photographs, and computer assistance. Fares et al. introduced a new modified scoring system of classifying dental erosions.[10,13,14]

The vague criteria used in qualitative methods are mostly subjective, inclined to variability in recording the condition.[1,9,11,13] Quantitative measures assessing the tooth-wear are time-consuming, giving a cumbersome system of grading and are not sensitive enough to the clinical changes of tooth-wear. The indirect method involves measuring tooth wear on dental casts and extracted tooth which takes into consideration a reference surface on the teeth not affected by tooth-wear.[9,11,15,16]

There is no ideal index reported yet, which can be used for epidemiological studies, clinical staging, and monitoring.[17] Our concern is to develop an easy index that may be used to assess the progression of abrasion. Hence, our study aims to design, develop, and calibrate its efficacy and assess the compliance of using a novel Cervical Abrasion Index of Treatment Needs (CAITN) probe to measure the cervical abrasion more objectively.

MATERIALS AND METHODS

Design and Development of the Cervical Abrasion Index of Treatment Needs Probe

CAITN probe is a newly developed instrument to measure cervical abrasion of the tooth more quantitatively. The overall length of the probe is 19.5 cm and graduated with 0–20 mm markings. The parts of the probe are beak with a needlepoint, shank, pivot points, shaft, scale, and finger rings. The finger rings are round with an inner diameter of 3 cm, length of 4 cm, 3 cm in width, and 2 mm thickness. The scale is 1 cm wide and has 0–20 markings in its 5 cm length on both sides.

The shaft is straight with 11 cm long, 3 mm wide, and 1 mm thickness, continuing from the scale and joints with the shank at the pivot points. From there, the shank is curved and tapered to form the beaks that face each other. The needlepoint emerges from the beak at right angles and is 3 mm long as shown in Figure 1a (Indian Patency Right Application Number: 201941043211).

Figure 1.

(a) Dimensions of Calibration of Cervical Abrasion Index of Treatment Need Probe. (b) Measurement of Cervical Abrasion using the Calibration of Cervical Abrasion Index of Treatment Need the Probe

The beak of the instrument is engaged either in buccopalatal or lingual direction and is locked to record the buccolingual measurement. The beaks of the CAITN probe was engaged into the deepest portion of the cervical abrasion part of tooth in perpendicular to the long axis of tooth, with an assistance of a mouth mirror for retraction and also for better visibility to avoid gingival piercing in the buccal and palatal marginal area of the gingiva. The measurement reflected on the CAITN probe scale is easily equated against standardized mesiodistal and buccolingual measurement of that tooth to obtain the depth of cervical abrasion [Figure 1b].

Sample size and technique

Assuming the expected population standard deviation to be 2.4, and employing t-distribution to estimate sample size, the study would require a sample size of 100 to estimate a mean with 95% confidence and a precision of 0.5.

Study method

The cross-sectional study was conducted according to the guidelines of the Helsinki Declaration. Ethical approval was obtained from the Institution Ethics Committee and informed consent was obtained from the study paticipants. Ten interns were initially trained with 10 patients with cervically abraded tooth for recording and reading the CAITN probe. Its compliance and usage were assessed by a set of standardized questionnaires given to the ten interns. It is then followed by an ex-vivo study conducted as a part of the development of CAITN probe and index for standardization of the probe by comparison with the measurements on dental casts using Vernier caliper that served as gold standard as well as inter-examiner and intra-examiner reliability of the measured values obtained from CAITN probe.

Among the ten interns, two of them were chosen as trained examiners (Examiners 1 and 2) for recording purposes. Both Examiners recorded the intraoral buccolingual measurements of cervically abraded tooth of 100 subjects visiting the OPD and examiner 1 repeated intraoral buccolingual measurements of cervically abraded tooth of same participants again and examiner 2 recorded buccolingual measurements of cervically abraded tooth from the cast.

Before taking the intraoral buccolingual measurement, the patient was positioned in the chair with proper illumination using artificial light. The oral cavity of the patient was prepared and the tooth was dried thoroughly using a three-way syringe and cotton rolls to avoid slipping of the instrument due to moisture. The measurements reflected on the CAITN probe scale was recorded and transferred to the assessment form.

Cervical Abrasion Index of Treatment Needs Probe and Vernier Caliper measurement comparison

After the CAITN probe measurement was obtained, to compare it with the buccolingual measurements obtained using Vernier caliper (gold standard) extraorally, a putty-based impression was recorded by examiner 2 in the same patient's arches with cervical abrasion. The impression was disinfected and casts were poured immediately.

The variance of extraorally measured buccolingual measurements due to variations in impression material properties and their recording accuracy is crosschecked with that of intraoral measurements, on 10 participants with anterior tooth cervical abrasion who were additionally recorded with Vernier calipers intraorally.

Inter-examiner reliability was achieved by considering intraoral buccolingual measurements taken by examiner 1 and examiner 2 among the same 100 subjects. A good agreement was observed between two examiners with Kappa value of 0.83. Intra-examiner reliability was achieved by considering intraoral buccolingual measurements taken by examiner 1 among the same 100 subjects at two different periods (morning and evening) of the same day.

Cervical abrasion index of treatment need probe compliance

The compliance and usage of the CAITN probe was assessed by a standardized set of questionnaire given to 10 interns with whom the design and usage of instruments were discussed, demonstrated, and trained to use this instrument. The questionnaire consists of 10 questions ranging from the difficulty of handling the instrument, recording and reading the measurement, discomfort reported by the patient, etc.

Statistical analysis

The data were statistically analyzed using IBM SPSS Statistics for Windows, Version 26.0. South Asia- Bangalore: IBM Corp. Descriptive data including mean, standard deviation, were calculated for each group. Paired t-test was used to compare the mean values between two groups. Pearson's correlation was applied to assess the relationship between the variables. Bland–Altman plot was used to determine the level of agreement between the intra-examiner, inter-examiner reliability, and method comparisons at a 5% significance level.

RESULTS

Questionnaire on instrument compliance and usage revealed that 100% of interns had no difficulty in handling and in recording the measurements. However, 60% of interns had difficulty in recording the measurement of the maxillary posterior sextant. All the study participants have no discomfort or pain while recording the measurement. The sample consisted of 100 participants comprising 58% of males and 42% of females with a mean age of 49.12 ± 10.55 years and 49.07 ± 10.87 years, respectively.

Paired sample t-test showed that the CAITN probe and the gold standard were comparable and statistically insignificant (p = 0.818) [Table 1]. Table 2 shows that the intraoral buccolingual measurement and buccolingual measurement obtained from cast using the gold standard were comparable and statistically insignificant (p = 0.758).

Table 1.

Paired sample t-test to compare the observations between gold standard and new method

Observations by	n	Mean±SD	Mean difference	P
Gold standard	328	7.003±2.03	0.002	0.818
New method	328	7.002±2.04

SD: Standard deviation

Table 2.

Paired sample t-test to compare the observations between gold standard intraoral measurements and cast measurements

Observations by	n	Mean±SD	Mean difference	P
Gold standard (intraoral)	10	7.003±2.04	0.008	0.758
Gold standard (cast)	10	7.004±2.05

SD: Standard deviation

Pearson's correlation showed a very high positive correlation for cervical abrasion measurement between CAITN and gold standard methods and was statistically significant (r = 0.998, p < 0.001).

There were no inter-examiner and intra-examiner variability for measurement of CAITN probe and was statistically insignificant (p > 0.05) on paired sample t-test [Table 3]. The Pearson's correlation for cervical abrasion measurements of CAITN probe between examiners showed very high positive correlation and was statistically significant (r = 0.999, p < 0.001) and correlation coefficient at two different time intervals was also statistically significant indicating a high positive correlation (r = 0.993, p < 0.001).

Table 3.

Paired sample t-test to compare the inter-examiner and intra-examiner observations

Observations by	n	Mean±SD	Mean difference	P
Examiner 1	328	7.002±2.0320	−0.0015	0.564
Examiner 2	328	7.003±2.0326
Intra-examiner observations
Time 1 Time 2	328	7.015±2.0412	−0.0073	0.589

SD: Standard deviation

The Bland–Altman plot based on means of observation revealed no proportional bias occurred with the method comparison as well as inter-examiner and intra-examiner reliability at 95% confidence interval (p > 0.05) [Figures 2 and 3a, b].

Figure 2.

Bland–Altman analysis for method comparison

Figure 3.

(a) Bland–Altman analysis for examiner pairs. (b) Bland–Altman analysis at different time points

DISCUSSION

The present study proposes a new method of accurately determining the depth of cervical abrasion based on the CAITN score. The advantage of defining the depth of the lesion is that it is used to assess the severity of the condition and makes it easier to compare the progress of the condition during follow-up. The cervical abrasion was assessed only as one of the components of tooth-wear indices and there is no ideal index solely to determine the cervical abrasion.[12,13] The grading methods available, provide only subjective measurements and most of the indices are qualitative, descriptive, and time-consuming[11,18] which are major challenging issues. The higher score in the CAITN probe implies a pathological level of the depth and spread of the lesion of the affected teeth that could justify restorative treatment.

Eccles's index is one of the cardinal indexes which classified the lesions into early, small and advanced types.[10] Early indices by Smith and Knight assessed the severity of dental erosion, attrition, and abrasion or any combination of these conditions using computer assistance on dental casts and photographs. Barsdely et al. pioneered a new, simplified version of the tooth-wear index which was essentially a dichotomized score.[19] Thus, there was a need for a new system for evaluating the depth of abrasion based on the criteria for the ideal classification system such as naturalness, usefulness, simplicity, exhaustiveness, disjointness, and constructability as suggested by Murphy.[11,13]

In the course of this study, the primary investigator has sought to establish the usefulness of the questionnaire as a tool for obtaining information concerning comfort from the study participants and the interns themselves while using the CAITN probe. After careful considerations, the questionnaire construction, analysis, and pretesting of the questionnaire were done. An appropriate questionnaire was then developed to obtain useful information that serves as a valid pointer to the subjective estimate of the factors that influence comfort both for the study subjects and examiners.

A self-administered questionnaire which was presented to the interns was then collected at the end of each day. The questionnaire consisted of 10 closed-ended questions that are laid out to ensure that the questions are understandable, readable, and unambiguous. All the examiners were been explained the reasons for the survey and assured of complete anonymity. For this purpose, each questionnaire has been accompanied by a cover page that provides a brief description of the purpose of the study and instructions aimed at helping in the completion of the questions.

It became apparent that 60% of the interns found difficulty in recording the measurement in the posterior sextant. Of which, 67% experienced difficulty in recording the maxillary posterior sextant only while 33% reported difficulty in both the maxillary and mandibular posterior sextants. The difficulty revealed can be attributed to the limited mouth opening of the participants. All the examiners revealed that the probe is easy to handle, record the measurements. The analysis of the questionnaire signifies the usefulness and simplicity of the probe in the measurement of cervical abrasion. Merely obtaining a high response rate, however, is not proof enough of the efficacy of the questionnaire. Henceforth, the questionnaire was further subjected to split-half reliability which produced similar scores in each half of the questionnaire, indicating high reliability.

The study consists of assessing inter-examiner and intra-examiner agreement of measuring cervical abrasion using direct intraoral measurement with CAITN probe and intraoral measurement using Vernier caliper on dental casts, as a gold standard method. The inter-examiner and intra-examiner agreement study were performed on 328 teeth with cervical abrasion from 100 participants who were examined twice by two of the examiners. Deviations in the interpretation of the criteria were thus solved by giving a short introduction to the use of the probe, and calibration of all the examiners was done by scoring some individuals in common and discussing the results.

The results demonstrate the reliability of our method since they correlate with the gold standard method of assessing cervical abrasion using Vernier caliper on dental casts and direct intraoral measurement. The inter-examiner and intra-examiner scores were excellent and the reason probably being that all examiners had practiced the system by scoring their patients in the period between. Although the results indicate that there was good agreement between and within the examiners, the time dedicated to training was significant. Therefore, with some practice, the rating system should be well suitable for recording the depth of cervical lesions. Hence, the authors suggest that this method of assessment can be effectively used in daily dental practice.

Method comparisons (gold standard and new method) of two measurement techniques were also presented as Bland–Altman plot and regression analysis where the differences presented are statistically insignificant indicating no proportional bias between the two measures at 95% confidence interval (p > 0.05). The proportional bias for the inter-examiner and intra-examiner agreement was also evaluated using regression analysis and was statistically insignificant (p > 0.05) and the corresponding estimates of agreement interval at 95% confidence interval using Bland–Altman plot.

The variability between two measurement techniques (gold-standard vs. New method), the two examiners who measured the same group of 100 participants (inter-rater reliability), and repeatability of data recorded by one individual across two trials (intra-rater reliability) were found to be positively correlated with high statistical significance of p < 0.001.

The present study was thus conducted as a part of the development of the CAITN probe and index. From this study, the standardization of instruments in terms of validity, inter-examiner, and intra-examiner reliability was obtained. CAITN probe is mainly developed for recording the cervical abrasion of tooth more quantitatively. The buccolingual measurement obtained from each cervically abraded tooth is equated with the mesiodistal measurement of the tooth to estimate the final structural loss of each tooth. The positive results of this study are beneficial for further studies in the development of the CAITN index.

CONCLUSION

Indices form an integral part of the epidemiological studies to quantify a clinical observation and thereby reduce the subjectivity in measurement enabling a specific treatment plan for each case. The present study showed that the design and structure of the CAITN probe are standardized based on inter-examiner and intra-examiner reliability and gold-standard comparison which aids in determining the extent of the tooth structure loss due to cervical abrasion.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.