Are there correlations between radiographic grade levels and modified grade levels of periodontitis?

BACKGROUND: At the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions, periodontitis was reclassified according to a multidimensional staging and grading system. Grading takes variabilities in the rate of disease progression into account, relying on recognized progression risk factors, and is based on the assessment of bone loss at the worst-affected tooth in the dentition as a function of age, which is then modified by factors such as smoking and diabetes mellitus. In this context, the aim of this study was to determine whether there are correlations between radiographically calculated grades and grades modified by the presence of smoking or diabetes.
MATERIALS AND METHODS: In this descriptive study, individuals diagnosed with periodontitis according to the 2017 classifications were examined. The grade of periodontitis was measured using periapical radiography. A modified-grade level was assigned to the patients according to their glycated hemoglobin levels (in diabetics) or their smoking status.
RESULTS: The study included 341 individuals. No statistically significant relationship was revealed by Chi-square testing (P > 0.05) or in the kappa agreement index between the modified grades and the radiographic grades.
CONCLUSIONS: Although there was no correlation between radiographic grade and modified grade in smokers and diabetic individuals, increasing the grade score in these individuals in accordance with the 2017 classification provides clinicians the opportunity to develop a risk-based treatment plan, commensurate with the severity of periodontal disease and the level of risk. Copyright:

INTRODUCTION

Periodontitis is one of the most prevalent diseases of humankind, characterized by a microbial-associated and host-mediated inflammation causing alveolar bone destruction.[1] In the last 30 years, periodontitis classification has been modified several times in accordance with emerging scientific evidence.[23] In the 2017 classification, periodontitis previously considered chronic or aggressive was grouped under one category as “periodontitis” and reclassified according to a multidimensional staging and grading system.[4]

Staging relies on the extent and severity of periodontitis; it had been used as the key descriptor of periodontitis since the 1999 classification system. Staging involves four categories (Stages I–IV) based primarily on interdental attachment loss and marginal bone loss, and secondarily on complexity of treatment considering factors such as probing depths, tooth loss, and furcation involvement.[45]

Grading is a key aspect of the 2017 classification system that accounts for variability in the rate of periodontitis progression. Grading also relies on recognized risk factors for periodontitis progression and individual patients' systemic health. Grade was categorised according to disease progression rate as Grades A, B and C. Direct evidence is based on longitudinal observation of radiographs, whereas indirect evidence is based on bone loss assessment of the worst-affected tooth in the dentition as a function of age. Furthermore, a risk factor (smoking or diabetes) should therefore shift the grade score to a higher value independently of the primary criterion represented by the rate of progression.[45]

According to the 2017 classification system, grade is modified, regardless of the radiographically calculated grade, in the presence of smoking or diabetes. Individuals who smoke ten or more cigarettes per day are classified as Grade C, and individuals who smoke < 10 cigarettes per day as Grade B. In addition, diabetic individuals were diagnosed as Grade C if their glycated hemoglobin (HbA1c) ≥7 and as Grade B if their HbA1c <7.[45] The aim of this study was to determine whether there is any correlation between radiographically calculated grades and grades modified due to the presence of smoking or diabetes.

MATERIALS AND METHODS

Source of the data

A total of 341 individuals aged between 30 and 77 years were examined. All participants provided written informed consent, which was reviewed and approved by the ethics committee and was in accordance with the ethical standards established by the Declaration of Helsinki.

Selection criteria

For enrollment, the participants met the following inclusion criteria: (1) diagnosed with periodontitis according to the 2017 classification; (2) either a smoker or diabetic; and (3) having eight or more teeth present. Patients were excluded if they: (1) had received periodontal treatment in the past 6 months; (2) had a systemic disorder that affects periodontal condition (other than smoking or diabetes); (3) were both smokers and diabetic; and (4) consume alcohol.

Study design

In this descriptive study, the participants were categorized into two groups: the smoker periodontitis (SP) group and the diabetic periodontitis (DP) group. Smoking behavior was ascertained by self-report. All smokers reported their own number of cigarettes smoked per day and years of smoking duration. Diabetic condition was evaluated by HbA1c level.

Data collection

A comprehensive periodontal diagnosis was undertaken in the patient assessment procedure through periodontal charting and a panoramic radiograph. The patients were diagnosed by an experienced periodontologist (FK) as having periodontitis under these criteria: their interdental clinical attachment loss (CAL) was detectable at ≥2 nonadjacent teeth; their buccal or oral CAL was ≥3 mm with pocketing >3 mm detectable at ≥2 teeth; and the observed CAL could not be attributed to nonperiodontitis causes.[46]

Staging and grading

The stage of periodontitis was based primarily on the worst-affected tooth's interdental CAL. The grade of periodontitis was measured by worst-affected tooth's radiographic bone loss as a percentage of root length divided by the patient's age.[46] Periapical radiography was used to measure the grade of periodontitis. Linear measurements from the cementoenamel junction (CEJ) to the base of the osseous defect were used to quantify bone loss and linear measurements from CEJ to root apex were used to quantify root length.

Modified grade

The modified grade level of patients was assigned according to their HbA1c level and number of cigarettes smoked per day, by another investigator (AD) who was blind to the patients' radiographic grade levels. Individuals who smoke ten or more cigarettes per day are classified as Grade C, and individuals who smoke <10 cigarettes per day as Grade B. Diabetic individuals were diagnosed as Grade C if their HbA1c ≥7 and as Grade B if their HbA1c <7.[45]

Sample size calculation

The sample size was determined using the G*Power 3.1 program (Institut für Experimentelle Psychologie, Düsseldorf, Germany). Type 1 error (α) = 0.05, effect size = 0.50, and test power (1−β) = 0.80 were calculated. The sample size was determined to be a minimum of 244 individuals.[78]

Statistical analysis

Statistical Software Package version 17.0 (International Business Machines Corporation, New York, USA) was used for data analysis. Chi-square test and kappa index were used to determine the relationship between radiographic grades and modified grades.

RESULTS

A total of 341 individuals, 176 smokers (132 males and 44 females) and 165 diabetics (88 males and 77 females) comprised the study. The mean age of the SP group was 47.06 ± 9.94, ranging from 30 to 59 years. The mean age of the DP group was 54.27 ± 10.38, ranging from 36 to 77 years.

In the SP group, the mean number of cigarettes smoked per day was 12.31 ± 5.90; the mean years of smoking duration was 17.94 ± 11.36. In the DP group, the mean HbA1c level was 7.45 ± 1.42.

In the SP group, there was no statistically significant relationship (Chi-square test, P > 0.05; kappa agreement index, P = 0.942) between modified grade and radiographic grade. The kappa agreement index between the modified grade and the radiographic grade of individuals who smoked ten or more cigarettes per day was not statistically significant (P = 0.851). The kappa agreement index between modified grade and radiographic grade levels of the smokers who had smoked for 15 years or longer was not statistically significant (P = 0.374) [Tables 1 and 2].

Table 1

Relationship between modified grade and radiographic grade of smoker periodontitis group

Smoking Modified grade	Radiographic grade			Total	χ2	P*	Kappa index
	A, n (%)	B, n (%)	C, n (%)				ρ	P*
A	0	0	0	0	8.113	0.088	0.015	0.942
B	11 (16.66)	11 (16.66)	44 (66.68)	66 (100)
C	0	44 (40.0)	66 (60.0)	110 (100)

*P>0.05, statistically no significant difference. A – Grade A; B – Grade B; C – Grade C; n – number of individuals; P – p value; ρ – index of agreement; χ2 – chi square; n – number of individuals

Table 2

The kappa agreement index between the modified grade and radiographic grade of individuals who smoked ten or more cigarettes per day and who smoked for 15 years or longer

Smoking ten or more cigarettes per day Modified grade	Radiographic grade			ρ	P*
	B		C
B	0		11	−0.17	0.851
C	44		66
Smokers who smoked for 15 years or longer Modified grade	Radiographic grade			ρ	P*
	A	B	C
A		0	0	0.226	0.374
B	11	0	11
C	0	22	44

*P>0.05, statistically no significant difference. A – Grade A; B – Grade B; C – Grade C; P – p value; ρ – Index of agreement

In the DP group, there was no statistically significant relationship (Chi-square test, P > 0.05; kappa agreement index, P = 0.782) between modified grade and radiographic grade. The kappa agreement index between modified grade and radiographic grade levels of the diabetics with an HbA1c level of 7 or above was not statistically significant (P = 0.858) [Tables 3 and 4].

Table 3

Relationship between modified grade and radiographic grade of diabetic periodontitis group

Diabetes Modified grade	Radiographic grade		Total	χ2	P*	Kappa index
	B, n (%)	C, n (%)				ρ	P*
B	44 (50.0)	44 (50.0)	88 (100)	0.077	0.782	0.071	0.782
C	33 (42.85)	44 (57.15)	77 (100)

*P>0.05, statistically no significant difference. A – Grade A; B – Grade B; C – Grade C; P – p value; χ2 – chi square; ρ – index of agreement; n – number of individuals

Table 4

The kappa agreement index between modified grade and radiographic grade levels of the diabetics whose glycated hemoglobin level was ≥7

HbA1c ≥7 Modified grade	Radiographic grade		ρ	P*
	B	C
B	11	11	0.053	0.858
C	33	44

*P>0.05, Statistically no significant difference. A – Grade A; B – Grade B; C – Grade C; HbA1c – Glycated hemoglobin; P – p value; ρ – index of agreement

Nearly 25.0% of the SP group individuals' radiographic grade level was higher than modified grade level [Table 1], whereas 26.6% of the DP group individuals' radiographic grade level was higher than that of the modified grade level [Table 2].

DISCUSSION

In the previous classification system, the grade of periodontitis was included by identifying specific forms of periodontitis with high rates of progression or cases presenting with more severe destruction at a relatively early stage of life.[29] In the 2017 classification, the grade of periodontitis includes a retrospective analysis of the rate of progression of periodontitis, which provides additional information about the biological characteristics of the disease. Grading also features an assessment of the risk of further progression and an analysis of possible poor outcomes of treatment.[45]

Smoking and diabetes were identified as risk factors for periodontitis in the 2017 classification.[4] Individuals with diabetes and those who smoke are at greater risk for the incidence and prevalence of periodontitis and have more severe periodontal destruction than individuals without these risk factors. Periodontitis is significantly associated with poorer glycemic control, as measured by HbA1c, and pervasiveness of smoking.[1011]

In the 2017 classification, radiographic grade was reported as the primary criterion in determining the grade of periodontitis. If the patient has risk factors associated with greater periodontitis progression, the risk factors shift the grade score upward, regardless of the primary criterion.[46] In this study, we aimed to determine the relationship between radiographic grade and the modified grade as determined by risk factors such as smoking and diabetes.

This study included individuals who were diabetics and smokers, which are determined to be grade-modifying risk factors in the 2017 classification. There was no statistically significant relationship and correlation between the radiographic grades and the modified grades of participants. The radiographic grade level was generally lower than the modified grade level.

The reason for the difference between these two grade levels can be explained as follows: first, the radiographic grade shows the retrospective effects of the disease, whereas the modified grade is related to the future progression rate of the disease. Although the result of the radiographic grade is lower, these patients are shifted to the advanced level due to their modified grade. This is to reflect their greater need for maintenance treatment and their higher periodontitis recurrence risk.[1213]

Second, radiographic grade being higher than the modified grade can be explained as follow. The radiographic grade measurement is determined according to the bone loss of the worst tooth in the mouth, but the worst tooth may have already been extracted. Thus, the radiographic grade may be understated. Modifying the grade independently of the radiographic grade avoids this and allows the patients to be assigned to a higher risk class to encourage more effective control.[1415]

Third, the radiographic grade takes into account the patient's long-term bone destruction pattern to the present. Based on the current understanding of periodontitis, the rate of progression of periodontitis may vary among individuals and at different times.[1617] Bone destruction in active or passive periods of the disease may differ, regardless of the individual's risk factors, and it is recognized that previous bone loss in relation to the patient's age does not rule out the possibility of rapidly progressing lesions. Therefore, by modifying the grade, underestimating the actual risk for further disease progression can be prevented.[46]

Fourth, information about periodontal bone loss in relation to the age of the individual is obtained with radiographic grading, while parameters that allow predicting disease progression, such as percentage of bleeding on probing, loss of teeth from the total of 28, and a pocket depth >4 mm, are not considered.[1819] Grade modification considering the effects of these parameters in smokers and diabetic individuals provides clinicians the data needed to develop a higher risk-based treatment plan.[20]

Radiography is the commonly used method to detect and evaluate bone loss caused by periodontitis.[2122] Bitewing or periapical radiographs are generally accepted as the standard for the assessment of periodontal bone loss (PBL), while radiographic detection of PBL is also obtained from panoramic scans.[21] In this study, clinical examination and panoramic radiographs were used to diagnose the periodontal disease of individuals; periapical radiography of worst-affected tooth was used to calculate the radiographic grade. It should be mentioned that angulation of the X-ray beam may affect the position of the radiographic alveolar bone crest, but it was believed that expressing alveolar crest level as a ratio of bone height to root length was not influenced by beam angulation in this study because it is assumed that errors in the numerator and the denominator will cancel each other, resulting in an accurate bone score.[2122232425]

CONCLUSION

The conclusion to be drawn from this study is that, while no correlation was observed between the radiographic grade and the modified grade in smokers and diabetic patients, increasing the grade score for these individuals in accordance with the 2017 classifications provides clinicians the opportunity to develop a risk-based treatment plan in order to better prevent recurrent periodontal destruction.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.