Comparative study between two techniques for alveolar bone loss assessment: A pilot study

Abstract

Objective:

To conduct a comparative study between two techniques for assessment of alveolar bone loss.

Materials and Methods:

Absolute and relative techniques were evaluated. The sample consisted of 16 radiographs supposed to meet a single criterion: The reference points applied (Cementum-enamel junction (CEJ) alveolar bone crest and root apex) should be visible. Bone height was measured in the selected radiographs as the percentage of root length through both techniques. Data were submitted to the Statistical Package for Social Science software. Results obtained by both methods were converted into bone loss index values and then categorized. Sensitivity and specificity of the relative technique, compared to the absolute technique, were calculated. Wilcoxon test and the Bland and Altman's method were employed for comparisons. Significance level was set at 5%.

Results:

For the absolute and relative techniques, means of bone loss index were respectively of 4.81 (±2.25) and 4.75 (±1.80). Bone loss index ≥6 (alveolar bone loss ≥50%) was found in 5 (31.2%) teeth, in the absolute technique, and in 4 (25%) teeth, according to the relative technique. There was no statistically significant difference between both methods (P>0.05). According to the Bland and Altman's method, it was verified a bias of 0.06, and limits of upper and lower agreement of, respectively, 1.58 and –1.45. Sensitivity of 0.8 and specificity of 1 were found for the relative technique compared to the absolute one.

Conclusion:

There was no significant difference between the techniques evaluated, and the relative technique was found to be reliable for measuring alveolar bone loss.

INTRODUCTION

Pathologically, periodontitis can be defined as the presence of gingival inflammation at sites where has occurred both pathological detachment of cementum collagen fibers and apical migration of junctional epithelium. Inflammatory events associated with connective tissue attachment loss also lead to resorption of coronary portions of the support alveolar bone.[1]

Radiographic examination is a complementing mean of great importance to obtain the diagnosis of periodontitis, even though it does not reveal the real state of cellular activity, but shows the consequences upon dentoalveolar structures.[2–4] That, along with clinical examination, provides a detailed assessment of the bone defect, reaching a correct diagnosis of horizontal and angular alveolar bone loss. Besides diagnosis, imaging examination helps in planning treatment, periodic check-ups and, finally, in the prognosis.[2,4–8]

In the literature, there are descriptions of several techniques for assessment of alveolar bone loss. Compass, ruler, millimeter probe, grid pattern and software have been used in numerous studies worldwide.[9–14] Nevertheless, according to Fukuda,[15] there still seems to be no consensus on what would be the most appropriate measurement method for evaluating radiographically the bone level. Given this, the objective of this study was to conduct a comparative study between two techniques for assessment of alveolar bone loss.

MATERIALS AND METHODS

The research project was submitted and approved by the Human Research Ethics Committee at the University Centre of Joao Pessoa (PB/Brazil).

This study was characterized to have an inductive approach, comparative and statistical procedures and technique of direct documentation, by means of radiographic examination.[16]

The sample consisted of 16 radiographs belonging to 8 patients treated at the Clinics of Periodontology, Federal University of Paraiba (PB/Brazil), in the first half 2011. All material was provided by the patients after signing an informed consent term. Radiographs were taken by a single equipment (DabiAtlante, Electronic Spectro 70X^®), using AGFA Dentus M2 Comfort^® radiographic film, and employing parallelism technique with a radiographic positioner.

Radiographs were supposed to meet a single criterion: The reference points applied (Cementum-enamel junction (CEJ) alveolar bone crest and root apex) should be visible. Criteria such as sharpness, contrast, among others, were not taken into account. Bone height was measured in the selected radiographs as the percentage of root length by two different techniques: Absolute and relative technique.

Absolute technique

We measured, in millimeters, the distance between CEJ and the alveolar bone crest, as well as the distance between CEJ and the root apex. Bone loss percentage was determined by the difference between those distances multiplied by 100.

All measurements were made in different days within a dark ambience on the negatoscope by a single previously trained examiner, with the aid of a needle point compass and a millimeter ruler. Information was recorded in a form made by the researchers.

Relative technique

It was conducted by using the Schei ruler. It is a transparent plastic ruler [Figure 1] stamping 1 mm thickness along its margins and 10 equidistant lines radiating from a central point, each one representing a bone loss equivalent to 10%. The marking of 1 mm thickness represents the distance between CEJ and the alveolar crest in normal humans without bone loss.[17] This technique results in the determination of bone loss as a percentage of the original bone level, starting 1 mm below CEJ, regardless root length, its extension in the radiograph and direction of the X-rays beam. The bone crest level was defined as the point along the root where an intact lamina was found.

Figure 1.

Schei ruler - representative image

As for the absolute technique, data were registered in a form. For both techniques, after 30 minutes of evaluation, a 15-minute break was respected to avoid eyestrain.

Data analysis

Statistical analysis was performed using the Statistical Package for Social Science (SPSS) software for Windows, version 18. As a way to allow a comparison between results obtained in both methods, all percentage values were converted into bone loss index values [Table 1], as proposed by Teeuw et al.[14]

Table 1.

Bone loss in percentage of the total root length and the corresponding bone loss index

For comparison of the two methods, mean difference was analyzed by Wilcoxon test and P < 0.05 was accepted as statistically significant. Additionally, the Bland and Altman's method was used to compare techniques.

Alveolar bone loss ≥50%, in relation to the total root length, was classified as severe periodontitis.[18] Thus, data obtained from both methods were also transformed into two categories: Alveolar bone loss <50% (score 0 assigned) and alveolar bone loss >50% (score 1 assigned). The sensitivity and specificity of the relative technique, compared to the absolute technique, were calculated.

RESULTS

For the absolute and relative techniques, means (±standard deviation) of bone loss index were respectively of 4.81 (±2.25) and 4.75 (±1.80). Bone loss index ≥6 (alveolar bone loss ≥50%) was found in 5 (31.2%) teeth, in the absolute technique, and in 4 (25%) teeth, according to the relative technique. There was no statistically significant difference between both methods (P>0.05, Wilcoxon test).

Figure 2 shows a comparison of methods by the Bland and Altman's method. It was verified a bias of 0.06, and limits of upper and lower agreement of respectively 1.58 and –1.45.

Figure 2.

The Bland and Altman's Graph. Y-axis: There is a difference between the methods (bone loss index). X-axis: Mean between the methods (bone loss index). SD = Standard deviation

The results in Table 2 show a sensitivity of 0.8 and a specificity of 1 for the relative technique when compared to the absolute one. It found four out of five teeth with bone loss ≥50% and identified 11 out of 11 teeth with bone loss <50% when compared to the absolute technique.

Table 2.

Sensitivity and specificity of the relative technique compared to the absolute technique, based on the extent of bone loss in relation to root length

DISCUSSION

Radiographic assessment complements the periodontal clinical examination, contributing to the establishment of a diagnosis and being effective for a retrospective analysis of periodontal disease evolution.[1] Numerous scientific evidences have aroused attention to the importance of clinical and radiological follow-up of periodontal patients.[19–21] Nonetheless, there is still no consensus on the best technique for measuring bone level.[15] This study was designed in order to analyze the differences between two techniques for alveolar bone loss assessment.

When comparing techniques, the absolute one measured greater alveolar bone loss than the relative, but without statistically significant difference. Although evaluating different methods, Teeuw et al.[14] found that an analyzer software measured a greater extent of bone loss than the Schei technique, but no statistically significant difference was found as well. Albandar and Abbas[22] compared three techniques for measuring bone loss (absolute, Schei's and Bjorn's techniques (bone level as a percentage of the tooth). Absolute technique was found to demonstrate ease of reading, while the Schei's technique demonstrated greater ability to detect changes in bone level.

We used the Bland and Altman's method to evaluate concordance between both techniques, but some studies in the literature have used either correlation[23] or only association[24,25] to make comparisons of various radiographic methods. The Bland and Altman's method has been considered a good measurer of the magnitude of validity. It allows the evaluation of the pattern of agreement or disagreement between a given measure and the gold standard, and incorporates some tolerance limits.[26] The analysis by the Bland and Altman's method showed a bias of 0.06, which was not statistically significant. This difference found is clinically acceptable, since we found a high sensitivity and a perfect specificity of the relative technique in relation to the absolute one. Teeuw et al.[14] found that the mean of the differences of 95% of all measurements ranged within ±0.9 of bone loss index. They also found perfect sensitivity and high specificity between an analyzer software and Schei's technique, concluding that these differences were acceptable.

Most of the authors who have studied alveolar bone loss in either longitudinal or cross sectional investigations have expressed their measurements in mm. This technique is indeed more precise because it does not depend on the teeth length, a rather variable parameter.[27] However, the relative technique is also believed to be precise, because its results in the determination of bone loss as a percentage of the original bone level are independent of the root length and its extension in the radiograph as well as do not depend on the direction of the X-ray beam.

There was no significant difference between the techniques evaluated, and the relative technique was found to be reliable for measuring alveolar bone loss.