|Year : 2022 | Volume
| Issue : 4 | Page : 975-983
Treating periodontal disease for preventing adverse pregnancy outcomes: Overview of systematic reviews
Ghousia Sayeed1, Sheeja S Varghese2
1 Department of Preventive Dentistry, College of Dentistry, Riyadh Elm University, Riyadh, Saudi Arabia; PhD Scholar, Department of Periodontics, Saveetha Dental College, Chennai, Tamil Nadu, India
2 Department of Periodontics, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Chennai, Tamil Nadu, India
|Date of Submission||27-Sep-2022|
|Date of Decision||08-Oct-2022|
|Date of Acceptance||11-Oct-2022|
|Date of Web Publication||10-Feb-2023|
Dr. Ghousia Sayeed
Department of Preventive Dentistry, College of Dentistry, Riyadh Elm University, Riyadh
Source of Support: None, Conflict of Interest: None
To study systematic studies and analyze how treating periodontal disease might help to avoid unfavorable pregnancy outcomes. One of the most prevalent oral conditions affecting people is periodontitis. It has been observed that around thirty percent of the people in some populations. Periodontitis is found in 5–20% of the pregnant woman. It has been found that the management of periodontitis is safe in pregnancy through scaling and root planning. Preterm delivery and periodontal disease now have a clear link, according to current research. This finding has garnered significant interest of the clinicians and researchers. Five systematic reviews were judged to have excellent methodological quality (bias probability being little), whereas the remaining four received small ratings (immense or indistinct bias risk). Low-quality research supported the assumption that treating periodontal disease had a favorable impact, whereas studies with the best quality provided unambiguous evidence that no such benefit existed. Consistently inconsistent results from low- and best-quality trials were obtained. In high-quality studies, it was observed that the overall rate of preterm delivery periodontal disease treatment significantly lowered the (odds ratio 1.15, 95% confidence interval 0.95–1.40; P = 0.15). In addition, rate of low birth weight infants even after the therapeutics of periodontal disease did not lessen (odds ratio 1.07, 0.85–1.36; P = 0.55), spontaneous abortions/stillbirths (0.79, 0.51–1.22; P = 0.28), or on the whole poor pregnancy outcomes (37 weeks considered as preterm births and/or unprompted abortions/stillbirths) (1.09, 0.91–1.30; P = 0.34). The use of treatment modalities for periodontal disease and other medical procedures can lessen preterm labor. However, treating periodontal disease alone cannot be considered a successful tactic to reduce the likelihood of preterm delivery even if it is not associated with any other medicinal course.
Keywords: Periodontitis, pregnancy outcomes, systematic review
|How to cite this article:|
Sayeed G, Varghese SS. Treating periodontal disease for preventing adverse pregnancy outcomes: Overview of systematic reviews. J Datta Meghe Inst Med Sci Univ 2022;17:975-83
| Introduction|| |
Diseases of periodontium are very common in human beings. Periodontitis (inflammation of periodontium) is considered among the frequently observed diseases of the oral cavity found in human population. It has been observed that around thirty percent of the people in some populations. It has been estimated that periodontitis is found in 5–20% of the pregnant woman. It has been found that management periodontitis is safe in pregnancy through scaling and root planning., In recent times a significant relationship has been found which associates preterm birth (PTB) with periodontal disease. This finding is getting significant importance from the clinicians and researchers. There has been a lot of research in the field of the obstetric field on the prevalence, etiology, control, and prevention of PTB. Preterm prenatal morbidity and asscoaited mortality till today are one of the most important causes of preterm delivery, it has been shown. Hence, many researchers in recent time have carried out research and analysis to gather more proof to support the relationship between PTB and periodontitis [Table 1]. There have been several observational studies performed since 1996 to establish a significant relationship between periodontitis and PTB.,
The exact physiological and pathological basis of the involvement of periodontitis in PTB is not clear but there is concrete evidence to support the fact that periodontitis is significantly related to the preterm labor and situations which causes complications in pregnancy like restrictions in the growth of the fetus and preeclampsia. Vergnes and their associates performed a systematic review along with meta-analysis in the year 2005 in which seventeen observational studies were included. In most of these studies, a significant relationship has been found between periodontitis and PTB. This meta-analysis concluded that the chances of getting premature birth of neonates is three times greater in patients with periodontitis.,
It has been found in studies that inflammatory products and pathogens are released as a result of periodontitis. Cytokines are one of the types of these inflammatory products. These products are found to influence the amniotic fluid and embryo by means of transport through the hematogenous routes., It is, therefore, necessary to establish association between the PTB and periodontitis. Since it has been found that the management of periodontitis is very safe by means simple periodontal procedures such as root planning and scaling procedures therefore the occurrence of unexpected labor and other complications of pregnancy can be reduced by the management of periodontitisin the pregnant woman., This paper was written to provide an overview of the systematic reviews that were done to analyze the studies involving the link amid preterm delivery associated with periodontitis with respect to decline in the incidence of neonatal births before the end of the full gestation period once periodontal diseases are properly managed.
| Materials and Methods|| |
Search strategy and eligibility criteria
With no language restrictions and up to July 2021, two independent researchers (DM and AV) searched the Registry of Systematic Reviews in Cochrane Central, Web of Science database, and Medline using the search terms “periodontal problems/disease, periodontitis, and or gingivitis,” and “premature rupture of membranes “preterm labor, PTB, or low birth weight (LBW), or PTB, Prelabor rupture of the membranes (PROM), or LBW.” With the assistance of a third investigator, they compared the findings and came to a consensus about the suitability of the systematic reviews (IPP). In addition, we manually reviewed the most recent 2 years' worth of issues of two significant dentistry journals, reviewed all relevant systematic reviews' references, and performed utilizing the names of the scholars who served as lead authors on at least one eligible publication, do cross searches in Medline.
The inclusion criteria included all systematic studies that randomly assigned pregnant women to be given scaling and root planing treatment as opposed to no therapy or prophylaxis for periodontal disease. Systematic reviews were well thoughtout to be entitled if they incorporated patients who had periodontitis or gingivitis, which is a recognized form of periodontal disease, in accordance with the International Workshop for a Classification of Periodontal Diseases and Conditions. No matter how severe or deep the periodontal disease was, all systematic reviews were eligible. The inclusion criteria were any systematic studies that compared prophylaxis or no treatment at all for periodontal disease to scaling and root planing therapy for expectant mothers. According to the International Workshop for a Classification of Periodontal Diseases and Conditions, systematic reviews were regarded as being admissible if they had patients who had periodontitis or gingivitis, which is a recognized type of periodontal disease.
We concentrated on subgroups of suitable patients for systematic reviews that, in accordance with their procedure, comprised arms in which patients received concurrent periodontal disease therapy (such as antibiotics). We did not include systematic reviews that used tocolytic medications for patients with threatened preterm deliveries, nonrandomized systematic reviews, or pseudo-randomized systematic reviews in the analysis.
Data extraction and assessment of methodological quality
Data extraction process was carried out by AZ and IPP, two independent researchers. A consensus was obtained once the results were evaluated by a third researcher (NPP). From each limb of qualified systematic reviews, the names of the authors, the journal and year of publication, the country of origin, the enrollment years, the gestational age at enrollment, the gestational age at which periodontal disease treatment was completed, the number of patients who were randomly selected and eligible, the quantity of live births, and the inclusion criteria for patients were all taken into consideration. Using the Cochrane Risk of Bias tool, we additionally noted the systematic reviews' methodological quality. The systematic reviews' methodology was examined by two different researchers (NPP and DM), who came to an agreement.
The main conclusion was the proportion of safely delivered pregnancies that were premature (either naturally occurring or indicated) before 37 weeks of gestation (All randomized pregnancies, with the exception of patients who were lost to follow-up and those that resulted in spontaneous abortions or stillbirths.) The overall rate of unfavorable pregnancy outcomes, which includes the total number of PTBs (37 weeks), spontaneous abortions, and stillbirths among all patients who were randomly assigned, excluding those who were lost to follow-up, the total number of infants weighing under 2500 g among all successful pregnancies, and the total number of infants weighing under 2500 g among all unsuccessful pregnancies. The last three secondary outcomes were the frequency of spontaneous preterm deliveries, the prevalence of preterm delivery before 35 weeks of pregnancy, and the prevalence of children born to mothers weighing <1500 g.
To examine the relative risk of spontaneous abortion/stillbirth, LBW babies, and preterm delivery among the periodontal diseases treatment group and control group, we built two-by-two tables and computed the odds ratio for each primary study. We utilized the two tests with a threshold of significance Chi-square of 0.1 to examine the homogeneity of odds ratio estimates across all relevant studies, and we then used the I test to measure the degree of heterogeneity. When statistical heterogeneity was not obvious, we synthesized data from many research using either the fixed effects (Mantel-Haenszel) model or the random effects model (Der Simonian and Laird). We removed these systematic reviews from the final analysis whenever studies reported no occurrences in either arm (periodontal disease therapy or no periodontal disease treatment).
To analyze the data, we utilized Review Manager (RevMan) version 5 statistical software. All P values had a level of significance of 0.05 and were two-tailed.
| Results|| |
Characteristics of eligible systematic reviews
The automated search produced 6916 titles that may be of use. The eligibility for final inclusion of 113 papers was assessed following the removal of duplicates and evaluation of their titles and abstracts [Figure 1] and [Table 2].,,,
This comprehensive overview comprised 35 systematic reviews in all. These reported on a total of 120 distinct researches; each review comprised between 3 and 45 main studies. Thirty-seven nations carried out the initial study.
Methodological quality of systematic reviews
The methodological quality of the systematic reviews was evaluated using the Cochrane risk of bias tool. Eight of the pertinent systematic reviews reported using an appropriate randomized method, four reported using an appropriate kind of allocation concealment, and six reported using blinding. We considered five systematic reviews to have a minimal bias risk and overall outstanding methodological quality. The risk of bias was unknown for one study, but it was considered for the other five [Table 3].
Primary outcome-preterm birth (<37 weeks)
Every one of the pertinent systematic reviews included information on PTBs. In all, women receiving treatment for periodontal disease were linked to 364 PTBs, compared to 366 patients who did not. Odds ratio: 0.52, 0.38–0.72; P = 0.0001; however, high-quality studies did not support this conclusion (1.15, 0.95–1.40; P = 0.15). Scaling and root planing, a periodontal disease treatment, has been demonstrated to dramatically lower the likelihood of premature birth. When we combined all of the systematic reviews, heterogeneity was apparent, but not when we separately analyzed the high- and low-quality systematic reviews.
Eight of the qualified systematic reviews included information on the number of LBW babies. Heterogeneity was significant when all systematic reviews were taken into account (Q = 20.23, P = 0.005, I = 65%), but not for individual studies of high or low quality. Again, the effects of periodontal disease therapy varied across low and high-quality systematic reviews (odds ratios of 0.44, 0.30–0.66 (P = 0.0001) for lesser-quality systematic reviews and 1.07, 0.85–1.36 (P = 0.55) for best quality systematic reviews).
Data on stillbirths or spontaneous abortions were reported in every systematic review. Because they did not show any findings in the periodontal disease treatment and control groups, we excluded three systematic investigations from the closing analysis. For spontaneous abortion/stillbirth, the pooled odds ratio was 0.84 (0.58–1.22; P = 0.37), indicating that there was no change. When we combined the data individually for systematic reviews of good quality (odds ratio 0.79, 0.51–1.22; P = 0.28) and systematic reviews of low quality (1.00, 0.51–1.97; P = 1.00), the findings remained non-significant. Heterogeneity was minimal at best [Table 4].
|Table 4: Data obtained after analysis of treating periodontal disease for preventing adverse pregnancy outcomes|
Click here to view
Overall adverse pregnancy outcomes
All of the systematic reviews had data on the largely negative pregnancy outcome (preterm delivery, i.e., 37 weeks and spontaneous stillbirths or abortions). Heterogeneity was found and statistically significant (Q = 26.45, P = 0.003, I = 62%). Using either the random effects model or the fixed effects model, we observed no difference that was statistically significant (P = 0.15). Yet again, studies with low quality have a tendency to overstate the effectiveness of therapy for periodontal disease. In the present review, a separate analysis was conducted based on the procedural quality of systematic reviews, systematic reviews with little less-quality showed a sturdy and noteworthy outcome of periodontal disease treatment (odds ratio 0.55,0.41–0.73; P0.0001), although higher-quality research showed that treating periodontal disease had no impact on the observed results (odds ratio 1.09, 0.91–1.30; P = 0.34) [Figure 2]. Between systematic reviews of high and low quality, there were no differences.
| Discussion|| |
This thorough analysis of 23 systematic studies provided proof that periodontal therapy, when combined with other medical interventions, can help lower the incidence of premature delivery. However, when it is not combined with any other medical interventions, the periodontal disease treatment alone would not be regarded as the only effective strategy to lesser incidence of the premature delivery. Pregnant women may be encouraged to get regular dental checkups to assess their oral health and perhaps receive periodontal disease therapy. In addition, it should be explained to them that receiving such medication at the time of pregnancy is probably going to lower the chance of preterm labor and subsequent birth if babies who are underweight.,
Despite a wide variety of bacteria in the oral microbiome, Porphyromonas gingivalis and Fusobacterium nucleatum are the most common periodontopathogenic bacteria linked to intrauterine infection. The placental microbiome and the oral microbiota closely resemble one other, according to current research. F. nucleatum is linked to PTB, LBW pregnancies, and early-onset neonatal sepsis. It may also be found in placenta, amniotic cavity, chorioamnionitis, cord blood, and newborn stomach aspirates. When F. nucleatum is delivered intravenously to animals, some pro-inflammatory pathways mediated by toll-like receptors result in fetal death and premature delivery. Based on the explicit bacterial strain, P. gingivalis oral contagion leads to preterm labor, restricted fetal development, and decreased vascularization of the placenta in mice. Human chorionic villous tissue and amniotic fluid both contained P. gingivalis DNA, which has been connected to repeated preterm labor and babies with lesser birth weight, correspondingly. It has been proved in the literature that if P. gingivalis is present in placenta or the umbilical cord, can lead to preterm delivery or preeclampsia (PE).,
Meta-analyses conducted as part of systematic reviews often have the lowest bias risk. We computed population-attributable fractions using the overall values from the best reviews. These results indicate, even if they shouldn't be taken as causal evidence, that diseases of the periodontium throughout pregnancy greatly rises the largely chances of LBW and the PTBs. This highlights the critical role periodontal disease plays in terms of global health and the pressing need to identify the root causes and develop preventative methods to minimize the disease's heavy burden.,
Given the known associations between MetS and adult-onset chronic diseases, in addition to problems associated with pregnancy like PE and gestational diabetes mellitus (GDM) and later-life type 2 diabetes mellitus and cardiovascular disease, pregnancy may offer a window of opportunity for identifying women with MetS and an elevated risk of critical pregnancy outcomes as well as a later-life chronic illness. Elevated triglycerides, low-density lipoprotein cholesterol, and decreased high-density lipoprotein cholesterol are associated with a higher risk for GDM, PE, LGA, and spontaneous preterm delivery, despite the fact that most research to date has only examined specific metabolic components in pregnancy (sPTB). A brief analysis revealed that multiparous Greek women with early-onset MetS had preterm delivery rates that were three times greater. Other investigations that looked at the relationship between periodontitis and metabolic syndrome found two different kinds of associations: One where the prevalence of the metabolic syndrome is higher among people with periodontitis, and the other where periodontitis is aggravated in cases of the condition. This demonstrates a mutually reinforcing interaction between the two illnesses and may be explained by a cause-and-effect relationship that is highlighted by the persistent low-grade inflammation that is a hallmark of both the metabolic syndrome and the two pathologies we previously mentioned. Tumor necrosis factor, interleukin (IL)-1, IL-6, and PAI-1 are examples of inflammatory markers associated with metabolic syndrome that can upregulate periodontal disease when chronic periodontal inflammation aggravates systemic inflammation, insulin resistance, and endothelial dysfunction.,
Before this exceptionally detailed research, the data from the already available systematic studies regarding the alliance among diseases of the periodontium and a range of unfavorable pregnancy outcomes has never been completely synthesized. Following a detailed prespecified and peer-reviewed protocol, authors used a highly comprehensive search strategy, which included probing a large number of electronic literature databases, screening references and citations, as well as identifying ongoing systematic reviews. High-quality systematic reviews and meta-analyses were available to clarify the association between periodontal disease and preterm birth, LBW, preeclampsia, and preterm LBW. The chance of PTB can be greatly reduced when periodontal care is coupled with other medical procedures, according to research. This connection was corroborated by further facts through the reviews that pointed to higher-quality primary studies for a variety of outcomes. We provide substantiation that contradictory results in systematic reviews of diseases of the periodontium and poor pregnancy outcomes were mostly the effect of older research with a moderate to high risk of bias.,
Pregnant women may be advised to get regular dental checkups to evaluate their oral health as well as periodontal disease therapy to manage and prevent complications. They should also be informed that taking such medications during pregnancy will definitely reduce their chance of having PTBs of babies born with LBW.
Our exhaustive review also has certain restrictions. Numerous factors, like as tobacco use in the form of smoking, social and ecnomic standards, mother's age, and background, may exacerbate link between diseases of the periodontium and unfavorable pregnancy outcomes. The omission to take into consideration important variables may have contributed to the overestimation of the link and its results between diseases of the periodontium and poor pregnancy outcomes. Various original publications included in the systematic reviews used the term “periodontitis” in different ways.
More investigation is a requisite to establish if specific MetS apparatus function synergistically or autonomously. Furthermore, it may be useful to conduct studies that measure and scrutinize changes in the metabolic outline before conception, also during pregnancy,, as it is presently unclear if women in certain studies had a poor metabolic profile before pregnancy. Young women who are recognized as having poor metabolic health during pregnancy are more likely to experience pregnancy problems, and these women will probably require ongoing metabolic monitoring in the years after their pregnancies. Future research should include more studies.
| Conclusion|| |
We may draw the conclusion that periodontal therapy, when combined with other medical interventions, can assist to lower the prevalence of premature delivery. However, when it is not combined with any other medical interventions, the therapeutics of the diseases of the periodontium alone cannot be regarded as the only effective strategy to lower the incidence of premature delivery.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Spivakovsky S. Periodontal treatment for the prevention of adverse birth outcomes. Evid Based Dent 2018;19:12-3. doi: 10.1038/sj.ebd.6401286.
Iheozor-Ejiofor Z, Middleton P, Esposito M, Glenny AM. Treating periodontal disease for preventing adverse birth outcomes in pregnant women. Cochrane Database Syst Rev 2017;6:CD005297. doi: 10.1002/14651858.CD005297.pub3.
Corbella S, Taschieri S, Del Fabbro M, Francetti L, Weinstein R, Ferrazzi E. Adverse pregnancy outcomes and periodontitis: A systematic review and meta-analysis exploring potential association. Quintessence Int 2016;47:193-204. doi: 10.3290/j.qi.a34980.
Teshome A, Yitayeh A. Relationship between periodontal disease and preterm low birth weight: systematic review. Pan Afr Med J 2016;24:215. doi: 10.11604/pamj.2016.24.215.8727.
Ide M, Papapanou PN. Epidemiology of association between maternal periodontal disease and adverse pregnancy outcomes--systematic review. J Periodontol 2013;84(4Suppl):S181-94. doi: 10.1902/jop.2013.134009.
Sgolastra F, Petrucci A, Severino M, Gatto R, Monaco A. Relationship between periodontitis and pre-eclampsia: a meta-analysis. PLoS One 2013;8:e71387. doi: 10.1371/journal.pone.0071387.
Konopka T, Paradowska-Stolarz A. Periodontitis and risk of preterm birth and low birthweight--a meta-analysis. Ginekol Pol 2012;83:446-53.
Kunnen A, van Doormaal JJ, Abbas F, Aarnoudse JG, van Pampus MG, Faas MM. Periodontal disease and pre-eclampsia: a systematic review. J Clin Periodontol 2010;37:1075-87. doi: 10.1111/j.1600-051X.2010.01636.x.
Wimmer G, Pihlstrom BL. A critical assessment of adverse pregnancy outcome and periodontal disease. J Clin Periodontol 2008;35(8 Suppl):380-97. doi: 10.1111/j.1600-051X.2008.01284.x.
Xiong X, Buekens P, Fraser WD, Beck J, Offenbacher S. Periodontal disease and adverse pregnancy outcomes: a systematic review. BJOG. 2006;113:135-43. doi: 10.1111/j.1471-0528.2005.00827.x.
Xiong X, Buekens P, Vastardis S, Yu SM. Periodontal disease and pregnancy outcomes: state-of-the-science. Obstet Gynecol Surv 2007;62:605-15. doi: 10.1097/01.ogx.0000279292.63435.40.
Madianos PN, Bobetsis GA, Kinane DF. Is periodontitis associated with an increased risk of coronary heart disease and preterm and/or low birth weight births? J Clin Periodontol 2002;29(Suppl 3):22-36; discussion 37-8. doi: 10.1034/j.1600-051x.29.s3.2.x.
López NJ, Smith PC, Gutierrez J. Periodontal therapy may reduce the risk of preterm low birth weight in women with periodontal disease: a randomized controlled trial. J Periodontol 2002;73:911-24. doi: 10.1902/jop.2002.73.8.911.
Jeffcoat MK, Hauth JC, Geurs NC, Reddy MS, Cliver SP, Hodgkins PM, et al
. Periodontal disease and preterm birth: results of a pilot intervention study. J Periodontol 2003;74:1214-8. doi: 10.1902/jop.2003.74.8.1214.
López NJ, Da Silva I, Ipinza J, Gutiérrez J. Periodontal therapy reduces the rate of preterm low birth weight in women with pregnancy-associated gingivitis. J Periodontol 2005;76(11 Suppl):2144-53. doi: 10.1902/jop.2005.76.11-S.2144.
Michalowicz BS, Hodges JS, DiAngelis AJ, Lupo VR, Novak MJ, Ferguson JE, et al
.; OPT Study. Treatment of periodontal disease and the risk of preterm birth. N Engl J Med 2006;355:1885-94. doi: 10.1056/NEJMoa062249. PMID: 17079762.
Offenbacher S, Boggess KA, Murtha AP, Jared HL, Lieff S, McKaig RG, et al
.. Progressive periodontal disease and risk of very preterm delivery. Obstet Gynecol. 2006;107:29-36. doi: 10.1097/01.AOG.0000190212.87012.96.
Sadatmansouri S, Sedighpoor N, Aghaloo M. Effects of periodontal treatment phase I on birth term and birth weight. J Indian Soc Pedod Prev Dent. 2006;24:23-6. doi: 10.4103/0970-4388.22831.
Tarannum F, Faizuddin M. Effect of periodontal therapy on pregnancy outcome in women affected by periodontitis. J Periodontol. 2007;78:2095-103. doi: 10.1902/jop.2007.060388.
Newnham JP, Newnham IA, Ball CM, Wright M, Pennell CE, Swain J, et al
. Treatment of periodontal disease during pregnancy: a randomized controlled trial. Obstet Gynecol. 2009;114:1239-48. doi: 10.1097/AOG.0b013e3181c15b40.
Macones GA, Parry S, Nelson DB, Strauss JF, Ludmir J, Cohen AW, et al
. Treatment of localized periodontal disease in pregnancy does not reduce the occurrence of preterm birth: results from the Periodontal Infections and Prematurity Study (PIPS). Am J Obstet Gynecol. 2010;202:147.e1-8. doi: 10.1016/j.ajog.2009.10.892.
Govindasamy R, Periyasamy S, Narayanan M, Balaji VR, Dhanasekaran M, Karthikeyan B. The influence of nonsurgical periodontal therapy on the occurrence of adverse pregnancy outcomes: A systematic review of the current evidence. J Indian Soc Periodontol 2020;24:7-14.
] [Full text]
Lavigne SE, Forrest JL. An umbrella review of systematic reviews of the evidence of a causal relationship between periodontal disease and cardiovascular diseases: Position paper from the Canadian Dental Hygienists Association. Can J Dent Hyg. 2020;54:32-41.
Boggess KA. Choosing the left fork: Steven Offenbacher and understanding maternal periodontal disease and adverse pregnancy outcomes. J Periodontol. 2020;91(Suppl 1):S40-S44. doi: 10.1002/JPER.20-0090.
Daalderop LA, Wieland BV, Tomsin K, Reyes L, Kramer BW, Vanterpool SF, et al
. Periodontal Disease and Pregnancy Outcomes: Overview of Systematic Reviews. JDR Clin Trans Res. 2018;3:10-27. doi: 10.1177/2380084417731097.
Offenbacher S, Beck JD, Jared HL, Mauriello SM, Mendoza LC, Couper DJ, et al
. Maternal Oral Therapy to Reduce Obstetric Risk (MOTOR) Investigators. Effects of periodontal therapy on rate of preterm delivery: a randomized controlled trial. Obstet Gynecol. 2009;114:551-59. doi: 10.1097/AOG.0b013e3181b1341f.
Oliveira AM, de Oliveira PA, Cota LO, Magalhães CS, Moreira AN, Costa FO. Periodontal therapy and risk for adverse pregnancy outcomes. Clin Oral Investig. 2011;15:609-15. doi: 10.1007/s00784-010-0424-8.
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]