Effect of smoking on salivary composition and periodontal status.

BACKGROUND: The purpose of this study was to evaluate and compare the effect of smoking on the periodontal status and salivary composition of whole saliva in subjects with clinically healthy periodontium and chronic periodontitis.
MATERIALS AND METHODS: The study comprised of 400 subjects equally divided into four groups of non-smokers with clinically healthy periodontium, smokers with clinically healthy periodontium, non-smokers with chronic periodontitis and smokers with chronic periodontitis. Clinical measurements and non-stimulated whole saliva were obtained. Biochemical analysis of salivary total protein, calcium, magnesium and phosphorus was performed.
RESULTS: The clinical parameters of probing depth and clinical attachment levels did not reveal any statistically significant differences between the smokers and non-smokers groups. The plaque index and gingival index were significantly higher in smokers with periodontitis (P<0.05) as compared with non-smokers with periodontitis. On biochemical analysis of whole saliva, total protein, calcium, magnesium and phosphorus were reduced in smokers with periodontitis to 0.43±0.50 gm/dL, 3.47±1.49 mg/dL, 0.80±3.87 mEq/L Neo and 18.45±8.77 mg% from 1.70±2.09 gm/dL, 13.89±10.34 mg/dL, 1.26±0.90 mEq/L Neo and 29.23±16.02 mg%, respectively, in non-smokers with healthy periodontium.
CONCLUSION: The present study exhibited reduced concentrations of total proteins, calcium, magnesium and phosphorus in whole saliva in smokers with chronic periodontitis. It may thus be concluded that the analysis of salivary composition could be used as an auxiliary means of diagnosis.

INTRODUCTION

Periodontal diseases are a group of conditions affecting the supporting structures of the dentition. Periodontal tissues consist of a specialized form of oral mucosa known as gingiva, which has a keratinized epithelium and covers the alveolar bone. There is an epithelial attachment between the enamel of the tooth and the marginal gingiva known as junctional epithelium, which is formed when the tooth eruption is completed.[1]

Inflammation of the marginal gingival tissues is a common condition, and its extent and severity can be variable. This condition, known as gingivitis, can be modified by systemic and local influences. If not controlled at this stage, the disease may progress to chronic periodontitis, which is a result of response of host to microbial aggregations. This condition leads to irreversible destruction of the connective tissue attachment and alveolar bone.

Smoking is considered a major risk factor for the development and progression of periodontal diseases.[2-5] Grossi and coworkers studied the effect of cigarette smoking on the attachment apparatus and alveolar bone height; heavy smokers had greater odds ratio for both attachment loss and alveolar bone loss compared with non-smokers.[67] Bergstorm and Floderus Hyrhed in a co-twin control study have shown that smokers exhibited greater disease level than their non-smoker twins. Also, smoking has been shown to affect the response to surgical or non-surgical periodontal treatment.[8]

The salivary composition has been relatively less studied in smokers. A few of them that have been done show decreased levels of salivary antibodies (Ig A) in smokers as compared with non-smokers.[9] Smokers who exhibited greater plaque and calculus formation had also shown elevated calcium concentration and elevated calcium phosphate ratio in plaque.[10] Zuabi et al. found that subjects with established periodontitis exhibited elevated concentrations of salivary electrolytes and proteins. In their study, smokers exhibited greater disease level but reduced sodium, calcium and magnesium concentrations.[11]

The literature does not reveal any comprehensive study that determines and compares the salivary composition of smokers and non-smokers in periodontally healthy and diseased subjects. Therefore, the purpose of this study was to analyze and compare the effects of smoking on the salivary minerals in periodontally healthy and chronic periodontitis subjects.

MATERIALS AND METHODS

The study population comprised of 400 subjects ranging in age from 30 to 60 years, equally divided into four groups. The patients were selected from those attending the Department of Periodontology at the Vidya Shikshan Prasarak Mandals Dental College and Research Centre, Nagpur. The four groups formed were subjects with clinically healthy periodontium and who were non-smokers (Group I), clinically healthy periodontium who were smokers (Group II), chronic periodontitis patients who were non-smokers (Group III) and chronic periodontitis patients who were smokers (Group IV).

Before the study, the purpose and design of the study was explained to all the subjects and an informed consent was signed by them. Chronic periodontitis patients included in the study exhibited probing pocket depths ≥5 mm with a minimum of eight teeth, and also demonstrated radiographic bone destruction of more than 30% of the tooth sites in full-mouth intraoral radiographic examination. Those patients who consumed more than five cigarettes a day since the past several years were included in the smokers categories. All the participants were, in principle, periodontally untreated and had not undergone any periodontal surgical procedures. All the participants were systemically healthy and had no history of any antimicrobial or anti-inflammatory medications within the previous 3 months for any reason. The study protocol was approved by the Institutional Ethics Committee and was in accordance with the Helsinki Declaration of 1975, as revised in 2000.

Clinical measurements

Plaque index (PI),[12] gingival index (GI),[13] probing depth (PD) and clinical attachment level (CAL) measurements were recorded. PD and CAL were recorded to the nearest millimeter using the Williams graduated periodontal probe at four sites around each tooth (mesiobuccal, midbuccal, distobuccal and midlingual), excluding the third molars. One calibrated examiner (RL) obtained all the measurements so as to reduce intra-examiner variability.

Sample collection

All the saliva samples were collected prior to clinical measurements, usually between 9 am and 11 am. Subjects were instructed not to consume any food or liquids 2 h before sample collection. Non-stimulated saliva was collected from the oral cavity where it was allowed to accumulate at the floor of the mouth and was transferred in Eppendorf tubes.

Biochemical analysis

Biochemical analysis for calcium was performed using the cresolphtaleine complexona method in a fully automated Selectra E machine. Similar analysis for total protein and phosphorus was done in the fully automated Selectra E machine using biuret/end point methods and phosphomolybdate UV method, respectively. Analysis for magnesium was done by the calmagite method using a Microlab 200 semi-automated machine.

Statistical analysis

The data were analyzed using Statistical Package for Social Science (SPSS) version 11.5. The P-value was taken as significant when less than 0.05 (confidence interval of 95% was taken). Patients′ salivary parameters (total protein, calcium, magnesium and phosphorus) and clinical parameters (PD, PI and GI) were analyzed using two ANOVA tests and in-between comparison carried out by using post hoc (Tukey) Test, whereas CAL measurement among smokers and non-smokers with periodontitis patient was analyzed by the Student t-test.

RESULTS

When the clinical parameters were compared between groups [Table 1], the PI and GI showed significant differences between healthy and diseased sites (P<0.05), which indicates a proper selection criteria of patients included in all the four groups. The mean PI for non-smokers with periodontitis, smokers with periodontitis, non-smokers healthy and smoker healthy patients was 3.60 ± 0.54, 3.64±0.48, 1.40±0.19 and 1.41±0.22, respectively. The differences between non-smokers with periodontitis and smokers with periodontitis were not found to be statistically significant.

Table 1

Mean±standard deviation values of clinical parameters among the study groups

Similarly, the mean GI in non-smokers with periodontitis, smokers with periodontitis, non-smokers healthy and smokers healthy was 7.34±1.06, 7.42±1.03, 1.07±0.47 and 0.99±0.43, respectively. These scores indicate a much higher GI score in diseased patients, while the differences between smokers and non-smokers in periodontally diseased as well as healthy subjects were not found to be statistically significant.

Also, the other clinical parameters such as probing pocket depth and CAL did not demonstrate significant differences in smokers with periodontitis and non-smokers with periodontitis.

Analysis of the biochemical parameters [Table 2] revealed that salivary calcium levels decreased consistently, and were 13.89 ± 10.34 mg/dL, 9.99±9.64 mg/dL, 6.16±2.84 mg/dL and 3.47 ± 1.49 mg/dL in non-smoker healthy, smoker healthy, non-smokers with periodontitis and smokers with periodontitis, respectively. Other parameters such as salivary total protein, magnesium and phosphorous levels were reduced in patients of smokers with periodontitis as compared with non-smokers healthy groups, the differences being statistically significant.

Table 2

Mean±standard deviation values of salivary parameters among the study groups

DISCUSSION

Among the four groups of our study, there was little difference between the PI and GI of Group III and IV patients. Although smokers with periodontitis exhibited higher values of PI and GI as compared with non-smokers with periodontitis, these findings were found to be statistically insignificant. The findings of higher PI in smokers are similar to a large body of controlled cross-sectional studies[14] and longitudinal studies.[3614] However, the smokers with periodontitis patient group in our study showed a higher GI, which is contrary to the findings of Zuabi et al.[11] There have been other clinical trials in which the authors reported no difference in the accumulation in smokers and non-smokers.[815]

Comprehensive information on the biochemical composition of whole saliva in periodontitis patients belonging to smoking and non-smoking categories is almost non-existent. The salivary parameters that were evaluated in our research laboratory showed a considerable reduction of values from Group I, i.e. non-smoker healthy to Group IV, i.e. smokers with periodontitis. The differences among these groups is shown in Table 2, and were found to be statistically significant (P<0.05). These findings are consistent with those reported by Zuabi et al.,[11] who showed significantly smaller calcium, magnesium and sodium concentrations in smokers as compared with non-smokers.

Saliva exerts a major influence on plaque initiation, maturation and metabolism. Salivary flow and composition influence calculus formation, periodontal disease and caries. The inorganic components of plaque are predominantly calcium and phosphorous, with trace amounts of other minerals such as sodium and potassium. The source of inorganic constituents of supragingival plaque is primarily saliva; as the mineral content increases, the plaque mass becomes calcified to form calculus.[16] Some of the inorganic components of calculus are calcium, phosphate, magnesium and trace elements of sodium. Early plaque of heavy calculus formers contains more calcium and less potassium than that of non-calculus formers. Zuabi et al. found that non-smokers exhibited distinct salivary composition, characterized with significantly smaller calcium, magnesium and sodium concentrations compared with non-smokers.

In the present study, there was no statistically significant difference in the mean levels of clinical parameters between groups; except PI and GI, significant reductions were recorded between the levels of calcium, magnesium and phosphorous in smokers. These results are similar to the Zuabi et al.[11] study and are in contradiction to those obtained by Erdemir et al.[17] The differences could be attributed to the different techniques that were employed for biochemical analysis.

In conclusion, smokers with periodontitis exhibited reduced levels of total proteins, calcium, magnesium and phosphorus as compared with non-smokers with periodontitis, and the differences were statistically significant. It may further be hypothesized that changes in salivary composition might be useful to establish favorable response to periodontal therapy.