The influence of nonsurgical periodontal therapy on the occurrence of adverse pregnancy outcomes: A systematic review of the current evidence

Abstract

Background and Objectives:

The poor maternal oral health in the pregnancy has an impact on the fetus through the oral-systemic link. Various studies have proven the relationship between poor maternal oral health and the occurrence of adverse pregnancy outcomes. Hence, periodontal therapy becomes indispensable during pregnancy. Previous systematic reviews and meta-analysis conducted to assess the influence of periodontal therapy on the occurrence of adverse pregnancy outcomes have shown inconsistent results. Hence, we conducted the present review to assess the influence of periodontal therapy on the occurrence of adverse pregnancy outcomes including the studies published till date.

Materials and Methods:

We searched for the relevant studies using the databases PUBMED, MEDLINE, CINAHL, and EMBASE on the randomized controlled trials evaluating the influence of periodontal treatment on adverse pregnancy outcomes from 2000 to 2018. Nineteen studies were considered for the present review based on the predetermined criteria. The risk of bias tool by Cochrane was used to evaluate the risk of bias among the studies.

Results:

Among the studies included for the present review, the occurrence of preterm birth among the pregnant mothers who received periodontal therapy ranged from 0% to 53.5%, while in the control group, the range was 6.38%–72%. The rate of LBW among the mothers treated for periodontal disease ranged from 0% to 36%, and in the control group, it varied from 1.15% to 53.9%.

Conclusion:

With best possible evidence, it can be inferred that nonsurgical periodontal therapy is safe during pregnancy. Even though it does not completely avert the occurrence of adverse pregnancy outcomes, it can be recommended as a part of antenatal care.

INTRODUCTION

Adverse pregnancy outcomes (preterm birth [PTB], low birth weight [LBW], and preterm LBW [PTLBW]) remain an important public health problem as it is still encountered across several communities globally and pose a considerable challenge to health professionals. PTB is defined as live birth <37 weeks of gestation, and LBW was defined by the World Health Organization in 1976 as a birth weight lower than 2500 g. The proven risk factors for adverse pregnancy outcomes were young and advanced maternal age, multiple gestations, previous PTB, short cervix, low educational status, stress, diabetes, short interpregnancy interval, and fetal genotype.[1] Poor maternal health also plays an important role in the occurrence of adverse pregnancy outcomes. Periodontitis is a chronic destructive inflammatory disease affecting the supporting structures of the tooth which is initiated by the dental plaque with the predominance of Gram-negative anaerobic microorganisms and also mediated by the host inflammatory response. The transit of periodontal pathogens and inflammatory mediators from the periodontal pocket to the fetal placental unit triggering inflammatory cascade could be a plausible link between the periodontal disease and the occurrence of the adverse pregnancy outcomes. This association is inconsistent as shown in previous epidemiological studies.[2,3,4,5]

Various epidemiological studies have shown that periodontal therapy during pregnancy reduces the occurrence of adverse pregnancy outcomes.[2,6,7,8] Preventive strategies implemented during the antenatal period have shown to improve pregnancy outcomes and oral health. Recommendations from health experts suggest women to undergo dental examination and therapeutic intervention during the preconception stage and during pregnancy.[9] However, the consensus statement of the (European Federation of Periodontology-American Academy of Periodontology) EFP-AAP workshop concluded periodontal therapy during pregnancy with or without systemic antibiotics, does not reduce the overall rates of adverse pregnancy outcomes.[10]

Several systematic reviews and meta-analysis conducted to assess the effect of periodontal therapy on the occurrence of adverse pregnancy outcomes among mothers with poor oral health have yielded inconclusive results.[11,12] The discordant results can be attributed to the low quality of the trials and the inclusion of only few published studies. The methodologies used to assess the quality of the studies included were also controversial. Moreover, the previous reviews focused on studies published from 2000 to 2012. Considering the abovementioned limitations and the time gap in the literature, we conducted a systematic review to provide the best possible evidence for the plausible association between periodontal therapy and adverse pregnancy outcomes among pregnant mothers with poor oral health. We included the studies published until 2018 for this present review.

MATERIALS AND METHODS

Types of studies

Randomized controlled trials (RCTs) offer the best possible evidence for assessing the effectiveness of therapeutic procedures. Hence, we included all the RCTs that assessed the influence of periodontal therapy at least on any one of these adverse pregnancy outcomes (PTB, LBW, and PTLBW). Reviews, case reports, editorials, in vitro studies, commentaries, animal studies, qualitative studies, case–control studies, cohort studies, and studies reported in other languages except English were excluded from this review. Only full-text articles were included for the present review.

Types of intervention

1. Scaling and root planning

2. Oral hygiene instructions and maintenance therapy

3. Adjunctive use of antibiotics.

Types of outcome measures

1. PTB

2. LBW

3. PTLBW.

Search strategy

We searched for the relevant studies using the databases PUBMED, MEDLINE, CINAHL, and EMBASE on the RCTs evaluating the influence of periodontal treatment on adverse pregnancy outcomes from January 2000 to October 2018. The keywords used for searching the studies were periodontitis, adverse pregnancy outcomes, periodontal therapy, and periodontal treatment, PTB, LBW and PTLBW. Relevant articles were also hand searched.

Study selection and data extraction

The eligibility for the inclusion of the studies for the present review was assessed by two reviewers independently. The reviewers appraised the full text of the studies which assessed the influence of periodontal therapy on any one of the three adverse pregnancy outcomes (PTB, LBW, and PTLBW). The data were extracted from the studies by each reviewer independently which included information about the study design, study population, timing of intervention, and type of intervention and the occurrence of adverse pregnancy outcomes in a separate sheet. Meta-analysis was not done because of heterogeneity attributed to the variations in the timing of periodontal treatment, type of periodontal intervention, and the type of periodontal disease among the studies included in this review.

Quality assessment

Cochrane collaboration tool for assessing the risk of bias was used to assess the quality of the studies included in this review.[13] The tool helps to determine the internal validity of an intervention; usually, a treatment to control or eliminate a disease or a preventive measure to reduce the risk of having the disease. The source of bias in each study was independently appraised by two reviewers and judged as having an unclear, high, or low risk of bias. No study was excluded based on the Cochrane risk of bias tool.

Risk of bias in the studies included for review

Among the nineteen studies, thirteen studies [3,4,5,6,7,8,14,15,16,17,18,19,20] have reported adequate randomization while allocation concealment was reported only in seven studies.[4,7,17,18,20,21,22] Proper blinding of the participants and personnel was done in eight studies.[3,6,7,15,16,17,22,23] The outcome was assessed by the blinded investigator in eight studies.[6,7,15,16,17,21,23,24] Eleven studies [4,5,6,15,17,18,19,21,24] were categorized having a low risk of bias based on incomplete data. Twelve studies [3,4,5,6,12,14,15,16,18,19,22,25] discussed the study outcomes in a prespecified way [Table 1]. Majority of the studies have not explicitly explained about the adjustment of confounders such as age, gender, socioeconomic status, history of PTB, bacterial vaginosis, gestational diabetes, prenatal care, and maternal weight gain except for six studies [3,15,16,19,21,23] which controlled for the majority of confounders. This is one of the methodological characteristics used for the assessment of individual trials based on Cochrane collaboration tool.

Table 1.

Quality of the studies assessed using the Cochrane risk of bias tool

Author/years	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting
López et al./2002[15]	Low	Unclear	Low	Low	Low	Low
Jeffcoat et al./2003[7]	Low	Low	Low	Low	High	High
López et al./2005[21]	Unclear	Low	Low	Low	Low	Unclear
Michalowicz et al./2006[3]	Low	Unclear	Low	Low	Unclear	Low
Offenbacher et al./2006[22]	Low	Unclear	Low	High	High	Low
Sadatmansouri et al./2006[8]	Low	High	High	High	Unclear	Low
Tarannum and Faizuddin/2007[14]	Low	Unclear	High	High	Low	Low
Gazolla et al./2007[2]	Unclear	High	High	High	High	Low
Newnham et al./2009[19]	Low	Unclear	High	Low	Low	Low
Radnai et al./2009[6]	Low	Unclear	Low	Low	Low	Low
Offenbacher et al./2009[16]	Low	Unclear	High	Low	Unclear	Low
Macones et al./2010[17]	Low	Low	Low	Low	Low	High
Sant’Ana et al./2011[24]	Unclear	High	Unclear	Unclear	Low	High
Oliveira et al./2011[23]	High	Unclear	Low	Low	Low	High
Pirie et al./2013[4]	Low	Low	Low	Low	Low	Low
Weidlich et al./2013[18]	Low	Low	High	Low	Low	Low
Reddy et al./2014[5]	Low	Unclear	High	High	Unclear	Low
Khairnar et al./2015[20]	Low	Low	High	Unclear	High	High
Penova-Veselinovic et al./2015[25]	Unclear	High	High	Unclear	High	Low

RESULTS

Total studies identified through the database search were 967. After assessing the studies for the eligibility criteria, 24 studies considering the title and abstract were selected for full-text reading [Figure 1]. Five studies have been excluded as they did not report the incidence of birth outcomes,[26] did not evaluate clinical parameters,[27] participants were from a part of a cohort study,[28,29] and results of the study were analyzed as per the success of periodontal treatment.[30]

Figure 1.

Flow chart depicting the process of literature search

Patient characteristics

About 8761 pregnant women were included in 19 trials. The majority of participants in the trials included were in the second trimester of pregnancy. The mean age of the participants was 25.6 ± 2.5 years [Table 2].

Table 2.

Baseline Characteristics of the studies included in the review

Author/Year	Country	Total number of subjects	Timing of intervention	Pregnancy outcome	Odds ratio/Relative risk/Incidence/Risk ratio
1.Lopez/2002[15]	Chile	Treatment group - 200 Control group -200	9-21 weeks	PTLBW LBW PTB	OR -6.67 (1.89-23.52) OR -6.96 (0.81-59.62) OR-6.11 (1.3-28.53)
2.Jeffcoat/2003[7]	USA	Treatment group- 246 Control group- 120	21-25 weeks	PTB	OR-0.45 (0.15-1.28)/ RR-1.4 (0.7-2.9)
3.Lopez/2005[21]	Chile	Treatment group-580 Control group-290	28 weeks	PTB LBW PTLBW	OR-4.11 (1.73-9.73) OR-1.47 (0.32-6.54) OR-3.26 (1.56-6.83)
4.Michalowicz/2006[3]	USA	Treatment group -413 Control group-412	13-17 weeks	PTB LBW	Risk ratio1.17 (0.74,1.85) Risk ratio0.92 (0.58,1.45)
5.Offenbacher 2006[22]	USA	treatment group-56 Control group-53.	21 weeks	PTB	OR-0.26 (0.08-0.85)
6.Sadatmonsouri/2006[8]	Iran	Treatment group - 15 Control group-15	13-20 week	PTBLBW	RR-0.12 (0.01,2.45) RR-0.31 (0.01,8.28)
7.Gazolla/2007[2]	Brazil	Treatment group-266 Control group-62	<22 weeks	PTLBW	7.5% Incidence
8. Tarrannum/2007[14]	India	Treatment group-100 Control group-100	<22 weeks	PTB LBW	76.4% Incidence 53.9% Incidence
9.Radnai/2009[6]	Hungary	Treatment group-41 Control group-40	24 weeks	PTLBW PTB LBW	OR- 4.6 (1.3-15.5) OR- 3.4 (1.3-8.6) OR - 4.3 (1.5-12.6)
10.Newnham/2009[19]	Australia	Treatment group-538 Control group-540	20 weeks	PTB	OR -1.05 (0.7-1.58)
11. Offenbacher/2009[16]	USA	Treatment group-903 Control group-903	23 weeks	PTB LBW	OR-1.22 (0.09-1.66) OR-1.01 (0.72-1.42)
12. Macones/2010[17]	Philadelphia	Treatment group-376 Control group-380	NA	PTB PTLBW	RR - 1.38 (0.92–2.08) RR -1.19 (0.62-2.28)
13.Santana/2011[24]	Brazil	Treatment group-16 Control group-15	9-24 weeks	PTB	OR-13.50 (1.47-123.45)
14. Oliveria/2011[23]	Brazil	Treatment group-122 Control group-124	12-20 weeks	PTB LBW PTLBW	RR-0.927 (0.601-1.431) RR-0.735 (0.459-1.179) RR-0.915 (0.561-1.493)
15. Weidlich/2011[18]	Brazil	Treatment group-122 Control group-124	12-20 weeks	PTB	RR-1.25 (0.87,1.78)
16. Pirie/2013[4]	Northern ireland	Treatment group-49 Control group-50	22 weeks	PTB- LBW-	RR-4.08 (0.47-35.24) RR-3.06 (0.33-28.43)
17. Reddy/2014[5]	India	Treatment group-49 Control group-50	22 weeks	PTB LBW	10% Incidence 20%Incidence
18.Khairnar/2015[20]	India	Treatment group-50 Control group-50	<22 weeks	PTB LBW	OR -0.54 (0.38-0.77) OR -0.78 (0.50-1.21)
19.Penova vaselinovic/2015[25]	Australia	Treatment group-50 Control group-50	<22 weeks	PTB	OR -0.33 (0.04-2.99)

OR-Odds ratio, RR-Relative risk, NA – Not applicable, PTLBW-Preterm low birth weight, PTB- Preterm birth, LBW-Low birth weight

Population characteristics

The studies were conducted on different countries among homogenous population in Chile,[15,21] Iran,[8] India,[5,14] Hungary,[6] Ireland,[4,11] Brazil [22] and heterogeneous population in U.S.A [3,7,16,17,18,22,23] and Australia.[19] The studies conducted among homogeneous population showed positive influence of periodontal therapy on the reduction of adverse pregnancy outcomes compared to studies done in heterogeneous population.

Study location

When compared to single center trials with a defined population,[6,7,14,15,21,22] multicenter trials with a larger population [3,16,17] showed negative results due to differences among the study population.

Criteria used for defining periodontal disease

The parameters used for assessing the periodontal status in the studies were probing depth, clinical attachment level (CAL), and bleeding on probing. Among the studies included in this review, there is a disparity in the criteria used for defining the periodontal disease. Some studies used CAL as the only criteria [7,14,17,22] to define periodontal disease, whereas other studies [3,5,6,12,21] used combination of probing depth, CAL, and bleeding on probing.

Periodontal intervention

There was heterogeneity among the studies considering the treatment options provided to pregnant mothers. The participants in the treatment group received oral hygiene instructions, full-mouth scaling, and root planning either in a single visit or multivisits and was followed till delivery. Only two studies [7,15] advocated the use of antibiotics as a part of the intervention. However, the results did not show any significant difference over the additional usage of antibiotics. Nine [7,8,14,15,17,18,19,20] of the RCTs used root planning as the only treatment option. The control group in the studies did not receive any active periodontal therapy during pregnancy [Table 3].

Table 3.

Periodontal characteristics of the participants from the studies included for the review

Author/years	Definition of periodontal disease	Type of periodontal disease	Type of intervention	Conclusion from studies
López et al./2002[15]	4 teeth with 1 site with PD ≥4 mm and CAL ≥3 mm	Mild to moderate	SRP and rinsing with 0.12% CHX maintenance 2-3 weeks till delivery	Periodontal therapy significantly reduces rates of PLBW
Jeffcoat et al./2003[7]	>3 sites with CAL loss ≥3mm	Moderate	SRP and rinsing with CHX maintenance 2-3 weeks till delivery	SRP reduces PTB
López et al./2005[21]	≥25% of sites with BOP and no sites with CAL >2 mm	gingivitis	SRP with 0.12% CHX	Periodontal treatment significantly reduces rate of PTB/LBW
Michalowicz et al./2006[3]	PD ≥4 mm and CAL ≥2 mm and BOP at≥35% of tooth sites	Moderate	SRP and OHI till needed till delivery	Periodontal treatment improves periodontal disease but does not alter pregnancy outcomes
Offenbacher et al./2006[22]	≥2 sites with ≥5 mm PD with CAL 1-2 mm ≥1 site and PD ≥5 mm	Mild	SRP with the use of sonic brush	Potential benefits of periodontal treatment on pregnancy outcomes
Sadatmonsouri et al./2006[8]	≥ 4 mm PD at≥4 teeth≥3 mm CAL at same site	Moderate to severe	SRP with 0.12% CHX	Periodontal therapy reduces the PTB rate
Gazolla et al./2007[2]	P1 - ≥4 teeth PD 4-5 mm and CAL - 3-5 mm. P2 - ≥4 teeth with PD and CAL of 5-7 mm at the same site. P3 - ≥4 teeth withPD and CAL 7mm at the same site	Moderate to severe	SRP, OHI with 0.12% CHX	Periodontal disease is significantly related to PTLBW
Tarannum and Faizuddin/2007[14]	≥2 mm attachment loss at ≥50% of examined sites	Moderate to severe	SRP with CHX and maintenance every 3-4 weeks	Periodontal therapy reduces the risk of PTB
Radnai et al./2009[6]	≥4 mm PD atleast at one site, BOP for ≥50% of teeth	Mild to moderate	SRP and plaque control	Periodontal treatment completed before 35th week have beneficial effect on birth weight and time of delivery
Newnham et al./2009[19]	PD ≥4 mm at ≥12 probing sites	Mild to moderate	SRP with CHX and maintenance every 3 weeks till delivery	Periodontal treatment does not improve pregnancy outcomes
Offenbacher et al./2009[16]	≥20 teeth with ≥3 sites with CAL ≥3 mm	Mild	SRP	Periodontal therapy did not reduce incidence of preterm delivery
Macones et al./2010[17]	CAL ≥3 mm on ≥3 teeth and ≥5 mm on ≥3 teeth	Moderate to severe	SRP	Periodontal treatment does not reduce the incidence of pregnancy outcomes
Sant’Ana et al./2011[24]	NA	NA	SRP and OHI	Periodontal treatment during second trimester did not reduce the risk for PTB, LBW and PTLBW
Oliveira et al./2011[23]	4 or more teeth with one or more sites with PD ≥4 mm and CAL ≥3 mm	Mild to moderate	SRP with maintenance every 3 weeks till delivery	Periodontal treatment during second trimester reduces the risk for PTB, LBW and PTLBW
Weidlich et al./2011[18]	4 or more teeth with one or more sites with PD ≥4 mm and CAL ≥3 mm	Mild to moderate	SRP with maintenance every 3 weeks till delivery	Periodontal treatment during second trimester reduces the risk for PTB, LBW and PTLBW
Pirie/2013[4]	≥4 mm at 4 or more sites and CAL ≥at 4 or more sites	Mild to moderate	SRP	Nonsurgical periodontal therapy completed at 20-24 weeks did not reduce the risk of adverse pregnancy outcomes
Reddy et al./2014[5]	Loss of attachment ≥1 mm, PPD ≥4 mm at 3 to 4 sites in >4 teeth	Mild to moderate	SRP	Treatment reduces pregnancy outcomes
Khairnar et al./2015[20]	PD >2 mm, CAL at 50% examined sites	Mild to moderate	SRP with 0.2% CHX rinse once a day	Nonsurgical periodontal therapy can significantly reduce the risk of PTB and LBW deliveries
Penova-Veselinovic et al./2015[25]	PD ≥3.5mmat 25% of sites	Mild to moderate	Nonsurgical debridement of sub and supragingival calculus and overhanging restoration	Periodontal disease treatment in pregnancy improves periodontal parameters with no effect on pregnancy outcome

NA – Not applicable; SRP – Scaling and root planning; PD – Probing depth; CAL – Clinical attachment level; BOP – Bleeding on probing; RR – Relative risk; PTB – Preterm birth; LBW – Low birth weight; PTLBW – Preterm LBW; CHX – Chlorhexidine; OHI – Oral hygiene instruction

Optimal timing of treatment

The timing of periodontal intervention is a crucial factor which determines the success of periodontal treatment in reducing the adverse pregnancy outcomes. Most of the studies have discussed the optimal timing of periodontal intervention, which was between 28 and 32 weeks of gestation.[2,14,20,21,25]

Outcome measures considered

The outcome measures considered were the occurrence of PTB, LBW, and PTLBW. Twelve [2,5,6,7,8,14,15,20,21,22,24,25] of 19 studies showed the positive influence of periodontal therapy on pregnancy outcomes, and seven studies [3,4,16,17,18,19,23] reported no significant effect of periodontal therapy on pregnancy outcomes. Among the studies included in the present review, the occurrence of PTB [3,4,12,13,17,18,20,21,22,25,26] among the individuals who received periodontal therapy ranged from 0% to 53.5%, while in the control group, the range was 6.38%–72%. The occurrence of LBW [5,14,15,16,17,18,19,21,23] among the individuals treated for periodontal disease ranged from 0% to 36%, and in the control group, it varied from 1.15% to 53.9%. The incidence of PTLBW [2,6,7,15,18,21,23] among the test group ranged from 0% to 26.7%, whereas in the control group, it ranged from 4.15% to 79%. The odds of decreased occurrence of PTB, LBW, and PTLBW among the participants who received periodontal therapy when compared to the control group ranged 0.26–13.50, 1.008–4.3, and 1.05–5.49, consecutively.

DISCUSSION

Adverse pregnancy outcomes remain an important public health problem. Among the adverse pregnancy outcomes, PTB has been estimated as the cause for 28% of neonatal deaths.[31] The other adverse pregnancy outcomes are LBW, preeclampsia, and gestational diabetes. The proven risk factors for the adverse pregnancy outcomes were young and advanced maternal age, multiple gestations, previous PTB, short cervix, low educational status, and fetal genotype.[1] Periodontal disease among pregnant women poses a considerable risk for adverse pregnancy outcomes. Researchers have suggested that translocation of periodontal pathogens to the fetal placental unit or the release of inflammatory mediators by the periodontal pathogens, which spreads through hematogenous route, affects the fetus. Numerous epidemiological studies evaluating the relationship between maternal periodontal disease and adverse pregnancy outcomes have reported conflicting results.

Consistent evidence from systematic reviews and meta-analysis indicates that pregnant women with periodontal disease are at increased risk of adverse pregnancy outcomes.[32,33,34] A meta-analysis concluded that pregnant women with periodontal disease have a 2.8-fold increased risk of PTB.[32] Hence, periodontal care should be given to pregnant mothers to prevent the occurrence of adverse pregnancy outcomes. The mechanism of how periodontal treatment could reduce the occurrence of adverse pregnancy outcomes is uncertain. The possible explanation might be the treatment for periodontal disease reduces the oral bacterial load thereby minimizing the risk of bacteremia and seeding of the fetal placental unit with pathogens which cause infection and adverse pregnancy outcomes. Another possible mechanism might be the reduction in oral bacterial load would reduce the production of inflammatory mediators such as cytokines and prostaglandins associated with adverse pregnancy outcomes.[22,35]

The effectiveness of periodontal therapy in reducing the occurrence of adverse pregnancy outcomes may vary according to the study location and population characteristics. Studies done in USA [3,7,16,17] Australia [19] did not report the significant difference in the occurrence of PTB, LBW, and PTLBW, whereas studies done in Chile, Brazil, India, and Hungary [6,14,15,16,21] showed significant difference among them. The disparity maybe attributed to the sharing of similar characteristics with reference to age, gender, and exposure of risk factors of PTB among homogeneous population.

Among the studies included in this review, single center trials with a defined population [6,7,14,15,21,22] provided positive influence of periodontal treatment when compared to multicenter trials with a larger population [3,16,17] which showed negative results. The inconsistency of the study results can be attributed to the differences in the study population and providing patient care in case of multicenter trials.

Timing of periodontal intervention is a crucial factor which determines the efficacy of reducing signs and symptoms of periodontal disease and associated inflammatory response thereby its impact on reducing adverse pregnancy outcomes. Most of the studies discussed the optimal timing of treatment to be between 28 and 32 weeks.[2,14,20,21,25] While in some studies, periodontal intervention was carried out before 24 or 28^th week,[3,7,8,23] and in a study done by Jeffcoat et al.,[7] the treatment was given before 35^th week of gestation. Majority of large clinical trials did not show positive influence of periodontal therapy on adverse pregnancy outcomes when treatment was given in the second trimester.[3,16,17] The underlying mechanism being the intervention provided too late because by the time periodontal bacteria would have reached the fetoplacental unit and have initiated the process of adverse pregnancy outcomes.[36] Hence, if the adverse pregnancy outcomes could be linked to the presence of periodontal pathogens and inflammatory mediators, the correct timing of treatment could be before pregnancy or in the early stages of pregnancy.

The criteria used for defining the periodontal disease also differed among the studies considered for the review. Four studies [7,14,17,22] used CAL as the only criteria to define periodontal disease, whereas other studies [3,5,6,21] used a combination of probing depth, CAL, and bleeding on probing. Hence, standardized criteria should be used for defining periodontal disease to assess the influence of periodontal therapy on the occurrence of adverse pregnancy outcomes without any disparity among the study results.

Most of the studies included in this review assessed the influence of periodontal treatment on PTB and LBW and only a few studies reported stillbirth as one of the primary outcomes.[3,19] Most of the studies reporting the success of periodontal therapy in this review considered mild to moderate cases of periodontitis because in severe cases, there is systemic dissemination of microorganisms and the infection does not completely resolve.[11,37,38] Hence, the study results cannot be generalized to individuals with severe periodontal disease.

Among the studies included in the review, the treatment and control groups were comparable with reference to the periodontal characteristics and exposure of risk factors. In majority of the studies, the treatment group received full-mouth scaling, root planing with oral hygiene instructions and followed by maintenance till delivery.[3,14] Few studies reported the use of chlorhexidine rinse as an adjunct to scaling and root planing [2,7,8,21] with significant results for control of periodontal disease. Among the control groups, only periodontal examination was done before delivery in some studies.[3,6,21] While in few studies, control groups received periodontal treatment after delivery.[2,14] Both the groups were followed until delivery for the assessment of birth outcomes.

Studies with high risk or unclear risk of bias [2,5,6,7,8,14,15,20,21,22,24,25] supported the beneficial influence of periodontal treatment in contrary to studies with low-risk of bias.[3,4,16,17,18,19,23] Hence, the influence of periodontal treatment on adverse pregnancy outcomes is uncertain, and further studies without the risk of bias evaluating the influence of periodontal treatment on adverse pregnancy outcomes should be conducted.

Previous systematic reviews and meta-analysis revealed a reduction in the occurrence of PTB with periodontal treatment in the population with the high-risk of the occurrence of adverse pregnancy outcomes.[11,39] However, in case of moderate risk of occurrence of events, the results were not statistically significant.[11,37,38] Polyzos et al. in his meta-analysis found that periodontal disease during pregnancy had no significant effect on the reduction of PTB rate (odds ration [OR] – 1.15, 95% confidence interval [CI]: 0.95–1.40)[40] supported by meta-analysis performed by Chambrone et al. and Fogacci et al.[12,41]

In contrast to the above findings, George et al. in his meta-analysis found that periodontal treatment during pregnancy significantly reduces PTB (OR = 0.65, CI: 0.45–0.93).[39] In the recent systematic review, da Silva et al, concluded that intra-pregnancy non-surgical periodontal therapy decrease the level of inflammatory biomarkers from GCF and serum blood but it did not reduce the occurrence of adverse pregnancy outcomes.[42] The differences reported in the study findings can be explained by the variation in strategies applied and the trials included for meta-analysis.

The strength of this systematic review is pertained to the inclusion of RCTs of varied methodological quality. The probable limitations of this systematic review could be the search for the relevant studies pertaining to three databases only, and the studies in the English language only were included. With best available evidence, it is sufficient to state that scaling and root planing alone is not effective in reducing the occurrence of adverse pregnancy outcomes. Hence, this review highlights the need of further multicentered RCTs to be conducted with strict protocol, clearly defined criteria for the periodontal disease, and intervention during the early stages of pregnancy or preconception to assess the influence of periodontal therapy on adverse pregnancy outcomes.

CONCLUSION

The present systematic review concluded that nonsurgical periodontal therapy during pregnancy is safe, but it does not completely reduce the occurrence of adverse pregnancy outcomes. Since nonsurgical periodontal therapy shows significant reduction in the occurrence of adverse pregnancy outcomes among high-risk patients, it can be included as a part of antenatal care.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.