| Abstract|| |
Background: Periodontal infections, which serve as a reservoir of inflammatory mediators such prostaglandin E 2 (PGE 2 ), may pose a threat to the fetal-placental unit and cause preterm delivery.
Aim: This study was conducted to estimate the PGE 2 levels in gingival crevicular fluid (GCF) and to explore the association between GCF-PGE 2 levels and preterm low birth weight (PLBW).
Materials and Methods: Twenty-two pregnant patients were selected for the study. GCF samples were collected from these patients before delivery and again at 1 month after delivery. PGE 2 level was estimated using a commercially available ELISA kit (Neogen™).
Results: The mean GCF-PGE 2 level was 5.8 ng/ml before parturition and 5.5 ng/ml after parturition, but the difference was not statistically significant. There was negative correlation between PGE 2 levels and gestational age at birth.
Conclusion: The study provides weak evidence that there is correlation between GCF-PGE 2 levels and birth outcome. Further clinical trials with large samples are required to confirm the association between GCF-PGE 2 levels and PLBW.
Keywords: Gingival crevicular fluid, periodontal diseases, preterm low birth weight, prostaglandins
|How to cite this article:|
Tarannum F, Faizuddin M. Association between gingival crevicular fluid prostaglandin E 2 level and preterm low birth weight. Indian J Dent Res 2012;23:120
Preterm birth is a major public health problem and the leading cause of neonatal morbidity and mortality. Despite its importance, identification of patients at risk for preterm delivery is difficult. Current methods of detecting patients at risk for preterm delivery largely rely on obstetric history, demographic factors, or premonitory symptoms that are neither sensitive nor specific. Biochemical markers are being developed in the hope that they could predict which patients are destined to have a preterm delivery.
|How to cite this URL:|
Tarannum F, Faizuddin M. Association between gingival crevicular fluid prostaglandin E 2 level and preterm low birth weight. Indian J Dent Res [serial online] 2012 [cited 2021 Dec 4];23:120. Available from: https://www.ijdr.in/text.asp?2012/23/1/120/99055
Compelling evidence now exists that infection is not only associated with preterm delivery but that it is a causative factor. , Infections affecting the mother during pregnancy may produce alterations in normal cytokine- and hormone-regulated gestation and result in preterm labor and preterm birth. 
Tissue destruction in periodontal diseases is mainly due to activation of immune cells by components of microorganisms, which stimulate production of inflammatory mediators.  There is ample evidence for the association between periodontal disease and preterm low birth weight (PLBW) and it has been postulated that the association between periodontal disease and PLBW may have similar pathogenic mechanisms as other maternal infections. ,
Prostaglandins are known to play a pivotal role in the initiation of labor during childbirth. There are extensive reports that suggest that serum PGE 2 levels increase at the onset of labor.  Inflamed periodontal tissues, which serve as reservoirs of inflammatory mediators, including prostaglandin E 2 (PGE 2 ), may pose a threat to the fetal-placental unit.  A case-control study has suggested that mothers giving birth to low birth weight (LBW) infants have higher mean GCF-PGE 2 levels than mothers having normal birth weight (NBW) infants and that the mothers with elevated GCF-PGE 2 were nine times more likely to be in the PLBW group. 
In the light of the above facts, the present study was conducted to estimate the PGE 2 levels in GCF before and after parturition and to explore the possibilities of utilizing GCF-PGE 2 levels in screening for risk of PLBW.
| Materials and Methods|| |
The sample population was selected from among pregnant women presenting for their prenatal checkups at the Department of Obstetrics and Gynecology, Dr. BR Ambedkar Medical College and Hospital, Bangalore, India. Patients were enrolled after obtaining the institutional ethical approval and informed consent from the patients for collection of the biological fluids. [Figure 1] shows the flowchart of the patient recruitment process and follow-up throughout the study. The subjects were recruited based on the following criteria:
- Pregnant women aged 18-35 years with clinical presentation of normal onset of labor, reporting either with their first or second pregnancy
- Single gestation of 28-32 weeks at the time of recruitment
- Subjects with ≥20 completely erupted teeth (excluding the third molars)
- Subjects with ≥3 mm attachment loss at not more than 30% of examined sites (moderate periodontitis)
- Patients who presented with clinically healthy gingiva and complied with the oral hygiene instructions
Measurement of periodontal status
- Mothers with diabetes, asthma, glomerulonephritis, hyperthyroidism, or history of congenital heart disease
- Use of corticosteroids/antibiotics during pregnancy
- Mothers with the habit of tobacco smoking, tobacco chewing, or alcohol use
- Any clinically evident systemic infection
Periodontal parameters measured were Oral Hygiene Index-Simplified (OHI-S),  Bleeding Index (BI),  and clinical attachment level. Full-mouth periodontal clinical attachment level (CAL) was measured at six sites per tooth using a UNC-15 (University of North Carolina) probe.
Oral hygiene instructions
Oral hygiene instructions included reinforcement of plaque control instructions [brushing and rinsing (with 0.2% chlorhexidine) twice daily]. Only those patients who complied with oral hygiene instructions and reported OHI-S of ≤0.5 and BI of ≤5% were considered for collection of biological fluids.
Collection of GCF and estimation of PGE 2
A GCF sample was collected from patients when they were admitted at the onset of labor and another sample was collected 1 month postpartum. We collected 5 μl GCF from sites with clinically healthy periodontium using micro-capillary pipettes (Sigma Chemical Company, St Louis, Missouri, USA). The samples of GCF were stored in plastic vials at −70°C until analyzed for PGE 2 level. Analysis was done using a commercially available ELISA kit (Neogen TM ).
Assessment of pregnancy outcomes
Preterm birth was defined as spontaneous delivery at <37 completed weeks of gestation and full-term birth (FTB) was defined as spontaneous delivery at >37 completed weeks of gestation. LBW was diagnosed when the infant had a birth weight <2500 g and normal birth weight (NBW) was diagnosed when the infant had birth weight ≥2500 g. Estimation of gestational age was based on the last menstrual period, ultrasound examinations, sequential physical examinations, and postnatal examinations.
A sample size of 25 subjects was estimated to be necessary to detect a difference of 1 ng/ml of PGE 2 with 80% as power of the study. Assuming an attrition rate of 15%, we decided upon a sample size of 30 subjects. The significance in the difference between mean GCF-PGE 2 levels before and after parturition was evaluated using the paired Student's 't' test. The correlation between PGE 2 levels and birth characteristics was evaluated using Pearson correlation coefficient. Statistical significance was at P<.05. Post hoc power analysis showed that the power of the test to detect the difference in serum PGE 2 levels was 91%, with a minimum detectable difference of 1.64 ng/ml, but for GCF it was 60%, with a minimum detectable difference of 0.35 ng/ml.
| Results|| |
The age of subjects ranged from 21 to 31 years. The mean age of the patients was 25.72 ± 2.64 years. All the patients belonged to low socioeconomic strata. [Table 1] shows number of infants with LBW and PTB.
The mean GCF-PGE 2 level was 5.80 ± 2.75 ng/ml before parturition and 5.50 ± 2.55 ng/ml after parturition; the difference was statistically significant. [Table 2] shows the mean PGE 2 levels among the LBW and PTB mothers. PGE 2 levels in NBW and FTB mothers were lower than in LBW and PTB mothers, but the difference was not statistically significant.
[Table 3] shows the correlation between PGE 2 levels and birth outcome. There was negative correlation between GCF-PGE 2 and birth outcome, with higher values of GCF-PGE 2 being associated with lower gestational age and birth weight.
| Discussion|| |
Biochemical markers were developed with the hope of giving the clinician new tools to predict and prevent preterm deliveries. High levels of cytokines like IL-1, IL-6 and TNF-α, PGE2, fibronectin, α-fetoprotein, and prolactin in amniotic fluid have been associated with increased risk of preterm delivery. The role of prostaglandins in human labor has been well documented. Amniotic fluid levels of PGE 2 rise steadily throughout pregnancy until a critical threshold level is reached, at which point labor is induced and cervical dilation and delivery take place. , PGE 2 is a major arachidonic acid metabolite released locally by macrophages. It has many proinflammatory effects on periodontal tissues. 
The association between periodontal disease and preterm births has been gaining attention over the past two decades. Hence, the present study was designed to explore the possibilities of developing GCF-PGE 2 levels as a predictor of risk of PLBW. Patients with known risk factors for PLBW were excluded from the study: Subjects above 35 and below 18 years, multiple gestation, and those presenting with systemic infections were excluded since all these factors are established risk factors for PLBW.  Subjects with a history of past or current use of tobacco (smoking and nonsmoking) or alcohol were excluded from the study as these are also known risk factors for PLBW. 
Inflamed periodontium is known to have higher levels of biochemical markers and, in the presence of inflammation in gingival tissue, the effect of changes induced by the pregnancy may be masked. Oral hygiene status was evaluated using stringent criteria before subjects were enrolled in the study. Only those patients who complied with the instructions and reported OHI-S of ≤0.5 and BI of ≤5% were considered for collection of biological fluids. Thus, the increase in PGE 2 in the study subjects is not due to poor oral hygiene because only those with clinically healthy periodontium were included.
GCF is a complex mixture of substances derived from serum, leukocytes, cells of the periodontium, and oral bacteria. It is a unique window for analysis of periodontal disease markers and determination of its constituents' levels has a practical diagnostic utility.  There are reports indicating that increase in serum levels of inflammatory mediators correspond to increase in their levels in GCF.  Since collection of GCF is noninvasive and easier compared to collection of serum, our study evaluated the correlation between PGE 2 levels in GCF and birth outcome. Our study shows that the mean GCF-PGE 2 level is higher before parturition than after parturition. Serum PGE 2 levels peak during the onset of labor and decrease significantly after parturition. These changes in the serum are reflected in the GCF and thus there is a decrease in PGE 2 levels in GCF after parturition.
Our results show that the mean GCF-PGE 2 level was higher in PTB mothers than in FTB mothers and was also higher in LBW mothers than in NBW mothers. Our study found a negative correlation between PGE 2 levels and birth outcome. Higher values of PGE 2 levels were associated with lower gestational age and lower birth weight. These results are similar to those of a study conducted by Offfenbacher, and co-workers which too found that PLBW mothers had a higher mean GCF-PGE 2 level than NBW mothers. 
The pathophysiology of spontaneous preterm delivery is poorly understood and substantive improvements in clinical management of preterm labor can come with better understanding of its pathophysiology. Only through investigations of the biochemical markers can we begin to understand the complex changes that occur during a preterm delivery, but none of the biochemical markers studied so far has turned out to be the solution for predicting preterm delivery.
The results of the present investigation should be interpreted in the light of its limitations. These limitations include the following: 1) the study design did not include a nonpregnant control group; 2) PGE 2 levels were not recorded before conception: Comparing the PGE 2 levels with a control nonpregnant group and with levels before pregnancy would have given a clearer idea of the effects of pregnancy and local inflammation on PGE 2 levels; 3) the sample size is small.
The results of this study provide weak evidence for the association between birth outcome and GCF-PGE 2 levels. Hence, it is premature to conclude that GCF-PGE 2 levels can be used as a predictor of risk of poor birth outcome. Further studies with larger samples are required to investigate the hypothesis.
| Acknowledgments|| |
The authors thank Dr. Hemalata M, Principal, MR Ambedkar Dental College and Hospital, Bangalore, Karnataka, India, for her cooperation during the study. The authors acknowledge the clinical and laboratory facilities provided by Dr. Gandhi, Principal, Dr. BR Ambedkar Medical College and Hospital, Bangalore, Karnataka, India. We also gratefully acknowledge the assistance provided by Mr. K.P. Suresh, Statistician, National Institute of Animal Nutrition and Physiology, Bangalore, Karnataka, India.
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Department of Periodontics, MR Ambedkar Dental College and Hospital, Bangalore, Karnataka
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3]