Keywords periodontal diseases - premature birth - adverse birth outcomes - pregnancy - evidence
Background
Premature birth: Epidemiology and etiology
Birth before the 37th week of pregnancy is the second leading cause of death for children
under the age of five, according to data from the WHO, and is also the leading cause
of neonatal
mortality and severe early and long-term morbidity [1 ]
[2 ]
[3 ]
[4 ]
[5 ]. Every year, about 15
million children are born prematurely worldwide [6 ]. In 50% of all spontaneous premature births, the etiology is uncertain [5 ]. Despite intensive efforts and advances in medicine, the rate of premature births
has not seen a significant global decrease [5 ]
[6 ]
[7 ]. That means that each
year nearly one million premature babies die in the first 28 days after birth [2 ]. Developing countries account for a large part of this
figure [6 ]. The rate of premature birth in Germany was 7.99% in 2020. Thus, Germany is among
the lowest in Europe. Preterm infants face
particular health risks due to the immaturity of their organ systems [2 ]
[3 ]. Among
other things, the immaturity of the central nervous system causes apnea, bradycardia
and temperature regulation disorders [3 ]. They
often suffer from long-term physical and mental limitations, developmental disorders
of the nervous system and breathing problems [2 ]
[5 ]. Last but not least, risks of clinical treatment, such as nosocomial infections,
must be taken into account.
Causal therapy for an impending premature birth is not yet possible. For medical reasons,
planned premature birth plays an important role in reducing the premature birth rate
[2 ]. A further starting point is risk-based prevention, which is of particular importance,
especially in the outpatient sector [2 ]
[7 ]. This includes, in particular, discussion of maternal dental health in
pregnancy.
Periodontitis in pregnancy
For many years, periodontology has been concerned with the potential connection between
the inflammatory foci in the oral cavity and systemic diseases such as diabetes, arthritis,
dementia
and cardiovascular diseases. Similarly, an association with undesirable consequences
for pregnancy such as premature birth, low birth weight and preeclampsia is discussed
[4 ]
[5 ]
[8 ]. Inflammation of the
periodontal bed (periodontitis) and gums (gingivitis) are common in women of reproductive
potential [5 ]
[8 ]. The risk of periodontal inflammation is increased especially during pregnancy,
and pre-existing gum disease tends to worsen during
pregnancy [4 ]
[5 ]
[8 ]
[9 ]. The occurrence of chronic periodontitis in pregnancy is reported in the literature
as 5% to 20%, and gingivitis as 30% to 100% [5 ]
[8 ]
[9 ]. The susceptibility of
pregnant women to inflammation in the oral cavity could be explained by the significantly
altered hormonal balance in pregnancy, which changes the tissue morphology in the
oral cavity [4 ]
[5 ]
[8 ]. Increased vascular
permeability, vascular proliferation and dilatation may contribute to susceptibility
to inflammation. However, immunological mechanisms could also play a role, since the
maternal immune
system is suppressed during pregnancy in order to prevent premature delivery (rejection)
of the fetus [5 ]
[8 ].
Periodontitis and risk of premature birth
With regard to premature birth, a much-discussed mechanism is the rise of bacteria
via the vagina and cervix into the uterine cavity [2 ]
[5 ]
[8 ]. This obvious mechanism has been relatively
marginalized in the scientific discussion in recent years in favor of other pathological
mechanisms in its weighting. Among other hypotheses, the question arises of a connection
between
inflammation in the oral cavity and pregnancy complications. One mechanism would be,
for example, the hematogenic spread of microorganisms in the oral cavity [5 ]
[8 ]. In the case of a periodontal infection, bacteria can pass via the pocket
epithelium into blood vessels and from there reach the fetal placental unit [5 ]
[8 ]. Thus, Katz et al. 2009 detected the periodontal bacterium Porphyromonas gingivalis
in the placenta of women with increased concentration of chorioamnionitis [5 ]. Indirect biological mechanisms could also explain a possible correlation between
inflammation of the oral cavity and premature births.
Through the oral infection, endogenous inflammatory mediators are increasingly excreted,
such as the tumor necrosis factor-α (TNF-α) [5 ]
[8 ]. The result is increased prostaglandin synthesis, which can lead to uterine contractions,
cervical dilatations
and premature rupture of membranes. Additively, bacteria and their products can reach
the liver and likewise cause an increased release of inflammatory mediators there
[5 ]. Kumar et al. 2014 were able to show that the serum level of TNF-α was statistically
significantly higher in women with periodontitis
and preeclampsia than in pregnant women with inconspicuous oral hygiene and preeclampsia
[5 ]. However, an alternative explanation could
also be that pregnant women who get a periodontal disease have a genetic predisposition
to an excessive local or systemic inflammatory response to a certain stimulus (e.g.,
bacteria) [5 ]
[8 ]. In addition to this explanation, it would also be conceivable to increase the
production of cytokines after contact with bacteria, which, for example, can lead
to premature labor or a rupture of membranes [5 ]
[8 ]. It remains to be seen whether the presumed association between dental health and
the risk of premature birth and the association with
other pregnancy complications can be confirmed epidemiologically.
Objectives of the paper
This paper is based on two research questions.
How can the correlation between periodontal disease in pregnant women and pregnancy
complications be assessed using meta-analyses and systematic reviews?
How can the efficacy of periodontal treatment vs. no treatment in pregnant women with
periodontal disease be assessed in terms of premature birth and other negative birth
outcomes (see
definition below) using meta-analyses and systematic reviews?
In this way, conclusions can be drawn for evidence-based midwifery in terms of proper
counselling during pregnancy, and gynecologists and midwives in private practice can
be supported in
clinical decision-making when caring for pregnant women.
Materials and Methods
Study design
The present study sees itself as a narrative review, which provides a broad overview
of a specific topic [10 ].
The PRISMA statement (Preferred Reporting Items for Systematic reviews and Meta-analyses)
is to be used to improve reporting of systematic reviews and meta-analyses. Consisting
of a
checklist and a flow chart, which is divided into four phases of a systematic overview
[11 ], the PRISMA statement was applied in some
parts due to its high relevance in the present study.
Primary and secondary outcomes
This narrative review examined the correlation between periodontal diseases and certain
outcomes. The primary outcome of the present narrative review is premature birth up
to a maximum of
36+6 weeks of pregnancy. Perinatal outcomes (low birth weight below 2500 g, very low
birth weight below 1500 g, low premature birth weight, low gestational age, premature
birth before 35
weeks of pregnancy or < 35 weeks of pregnancy [up to 34+6 weeks of pregnancy] or before
32 weeks of pregnancy or < 32 weeks of pregnancy [up to 31+6 weeks of pregnancy],
stillbirths)
and maternal outcomes (mortality, preeclampsia, undesirable effect of therapy, plaque
values, gum health, change in the depth of probing, change in the clinical attachment
values) were
defined as secondary outcomes.
Selection of studies
In February 2021, an electronic database search (PubMed and Cochrane database) was
conducted after relevant meta-analyses and systematic reviews, which was updated in
February 2022. Three
independent authors (AK, NF, DS) searched for relevant articles on the basis of the
previously defined inclusion and exclusion criteria. Finally, the search results of
all three authors were
combined as part of a collegial scientific exchange.
Search terms
In the studies used, the treatment of inflammatory gum diseases such as gingivitis
and periodontitis was mostly analyzed. No classification of the severity of the periodontal
disease has
been established.
The databases used for research were PubMed and the Cochrane database. For the research
on PubMed, the filters “Systematic Review” and “Meta-analysis” have been activated.
Another filter
was the inclusion of the publication of the studies in the period between January
1, 2010, and February 1, 2022. The search strategy was to connect relevant search
terms by the Boolean
operators. One search term describes the primary outcome of the present paper (“preterm
birth”), while another search term describes the intervention to be investigated (“periodontal
treatment”). These search terms were linked by the Boolean operators (e.g., “preterm
birth” AND “periodontal treatment”). Likewise, the search term of the primary outcome
(“preterm birth”)
was combined with the search term “periodontal disease” (e.g., “preterm birth” AND
“periodontal disease”). In the Cochrane database, the search term “periodontal disease”
was researched with
the filter of the “Cochrane Reviews”. The last search took place on February 14, 2022.
Inclusion criteria and exclusion criteria
One inclusion criterion was the study design of the meta-analysis. Studies that carried
out both a meta-analysis and a systematic review were also accepted. Only studies
that were written
in English and published between January 1, 2010, and February 1, 2022, were included.
The participants of the studies should represent women in pregnancy. In addition,
studies were included
that looked at the gestational age at birth in connection with periodontal diseases.
Another inclusion criterion was perinatal and maternal outcomes in the context of
periodontal diseases,
which are related to negative birth events. Studies analyzing the correlation between
premature birth and the treatment of periodontal disease were also included. All study
designs (e.g.,
observational or interventional study) as well as other literature (e.g., textbooks
or grey literature) apart from the systematic reviews and meta-analyses were excluded.
Studies which
exclusively represented the study design of systematic review work (not in combination
with meta-analyses) were also excluded.
Data extraction
The methodological characteristics of the included studies were analyzed and presented.
These presented the study type, country and intervention of the examined studies,
the characteristics
of the subjects, the study objective, the endpoints/outcomes as well as the inclusion/exclusion
criteria of the selected studies. The results of the included studies were also considered.
The endpoints and results of the studies were extracted. The relative risk (RR) or
odds ratio (OR) (95% confidence interval) was considered as an outcome measure of
the included
meta-analyses.
Evaluation of the quality of the included studies
High-quality review papers systematically identify the evidence, evaluate it methodically,
and summarize it descriptively or meta-analytically. Systematic distortions of systematic
reviews
should be evaluated [12 ]. To assess the quality of the included systematic reviews and meta-analyses, the
validated and frequently used
AMSTAR checklist was applied, which contains 11 key questions. The answer options
Yes, No, Uncertain and Not applicable were available for each key question. However, no
cut-off was planned for the overall assessment. For this review, the AMSTAR checklist
(A MeaSurement Tool to Assess Systematic Reviews) was applied in German, and with
a slightly modified
translation, taking into account the current standards – and was presented in tabular
form [12 ].
Results
Results of the narrative literature search
The electronic search in the databases yielded 13 results. After screening the abstract,
four articles were excluded. The eight remaining articles were evaluated in full text,
whereby one
article was excluded due to its low relevance for the question focused here. Finally,
seven articles [4 ]
[8 ]
[13 ]
[14 ]
[15 ]
[16 ]
[17 ] were included in
this narrative review (cf. [Fig. 1 ]). The seven meta-analyses and systematic reviews come from Great Britain, Spain,
Poland, Brazil, Canada and
Greece.
Fig. 1 Fig. Flow chart for narrative literature research according to the PRISMA Schema [11 ].
Methodological characteristics of the included studies
A total of seven studies were included in this narrative review. These studies presented
meta-analyses and systematic reviews. Four meta-analyses and systematic reviews [4 ]
[13 ]
[14 ]
[17 ] looked at randomized and controlled intervention studies (intervention periodontal
treatment vs. no treatment), whereas three
meta-analyses and systematic reviews included observational studies that analyzed
the association of negative birth outcomes with periodontal diseases [8 ]
[15 ]
[16 ]. The meta-analyses include studies from five
different continents (America, Europe, Asia, Australia, Africa) and seven different
countries (Chile, Iraq, India, Brazil, Malaysia, Madagascar, Canada). The number of
subjects in the
included studies varied between n = 6558 and n = 12047. For all the studies considered
here, the total number of female subjects was n = 56755. In all studies, pregnant
women represented the
subjects and the exposure was periodontal disease. In all the meta-analyses and systematic
reviews examined, the primary outcome was premature birth (< 37 weeks) [4 ]
[8 ]
[13 ]
[14 ]
[15 ]
[16 ]
[17 ]. In addition, in six of the seven [4 ]
[8 ]
[13 ]
[14 ]
[15 ]
[17 ] meta-analyses and systematic reviews, the low birth weight in SGA (< 2500 g) was
considered a primary
outcome. The secondary outcomes of the studies represented different maternal or perinatal
outcomes. The methodological characteristics of the studies are shown in detail in
[Table 1 ].
Table 1
Methodological characteristics of the included studies.
Study
Study type
Country and intervention of the examined studies
Identification of subjects
Study objective
Endpoints/outcomes
Inclusion/exclusion criteria
Iheozor-Ejiofor et al., 2017 [4 ]
Cochrane Review
Countries of the examined studies: 5 from North America, 4 from South America, 3 from Europe, 2 from Asia and 1 from
Australia.
Intervention of the examined studies: The intervention was periodontal treatment (any combination of mechanical treatment)
vs. no treatment in 11 studies and periodontal
treatment vs. alternative periodontal treatment in 4 studies.
Subjects: 7161 pregnant women
Exposure: Subjects with periodontitis or gingivitis
Further features: Subjects in the first or second trimester of pregnancy (except in 2 studies); severity
of periodontitis from moderate to severe
Goal: Investigation of whether the treatment of gum disease can prevent unfavorable birth
outcomes in pregnant women.
Primary outcomes: Perinatal outcomes (gestational age at birth, birth weight, low gestational age);
maternal outcomes (mortality, preeclampsia, adverse effect of
therapy).
Secondary outcomes: Maternal outcomes (plaque values, gum health, changes in probing depth; changes in
clinical attachment values)
Inclusion criteria: All randomized controlled trials investigating the effects of periodontal treatment
on the prevention or reduction of perinatal and maternal morbidity
and mortality.
Exclusion criteria: Studies in which the obstetric results were not reported were excluded.
Manrique-Corredor et al., 2019 [16 ]
Systematic review and meta-analysis
Countries of the examined studies: 8 studies from America, 6 from Europe, 5 from Asia and 1 from Africa.
Intervention of the examined studies: –
Subjects: 10215 pregnant women
Exposure: Periodontitis in pregnant woman
Goal: Examination of the correlation between periodontitis and premature birth in women
of childbearing potential.
Primary outcomes: Premature birth or no premature birth
Inclusion criteria: Inclusion of analytical case-control studies and prospective cohort studies. Studies
had to express associations with ORs. English or Spanish articles
have been taken into account. WHO definition of premature births.
Konopka et al., 2012 [15 ]
Meta-analysis
Countries of the examined studies: 8 studies from Europe, 7 from South America, 4 from North America and 3 from Asia.
Intervention of the examined studies: –
Subjects: 12047 pregnant women
Exposure: Periodontitis in pregnant woman
Goal: Examination of the influence of periodontitis on premature birth and low birth weight.
Primary outcomes: Premature birth before the 37th week of pregnancy; low birth weight below 2500 g
Inclusion criteria: Non-experimental, case-control prospective or cohort studies; exposure defined as
maternal periodontitis; cases with premature birth prior to the 37th
week of pregnancy or low birth weight below 2500 g; studies conducted in humans; only
case parameters were used in periodontal studies; only one (earliest) study conducted
by the
same group of authors was considered.
Da Rosa et al., 2012 [14 ]
Systematic review and meta-analysis
Countries of the examined studies: Studies come from Chile, USA, Iraq, India, Australia and Brazil.
Intervention of the examined studies: Treatment of periodontal disease compared to usual care.
Subjects: 6988 pregnant women
Exposure: Pregnant women with gingivitis in which ≥ 25% of areas bleed during probing and areas
with a clinical attachment loss of > 2 mm.
Further features: Women over 18 years of age with a single pregnancy of 22 weeks or less.
Goal: Examination of the correlation between periodontal effects, premature birth and low
birth weight as well as the reasons for the ongoing controversy in this field.
Primary outcomes: Premature birth (< 37 weeks), low birth weight (< 2500 g) and/or low premature birth
weight
Inclusion criteria: Studies had to specifically investigate treatments for periodontal diseases during
pregnancy, compare the results of the usual treatment and the
specific treatment, and report at least one outcome of interest. Including only randomized
studies whose subjects met certain criteria.
Boutin et al., 2013 [13 ]
Systematic review and meta-analysis
Countries of the examined studies: 5 studies from the United States, 1 from Australia and 2 from Chile, 2 from Brazil,
1 from Iran and 1 from India.
Intervention of the examined studies: The intervention (periodontal treatment) consisted of root planing and superficial
tartar removal (scaling) and was initiated in all
studies prior to week 28 of pregnancy.
Subjects: 7018 pregnant women
Exposure: Periodontal disease of the pregnant woman
Goal: To investigate the effects of periodontal treatment on the risk of premature birth
and to research the heterogeneity between studies.
Primary outcome: Premature birth, defined as a delivery before the 37th week of pregnancy.
Secondary outcome: Childbirth before the 35th and 32nd week of pregnancy, gestational age at birth,
birth weight, low birth weight, defined as a birth weight below 2500 g,
and very low birth weight, defined as a birth weight below 1500 g.
Inclusion criteria: RCTs in pregnant women with periodontal disease (all degrees of severity, including
gingivitis) who received either periodontal treatment (scaling and
root planing) or no treatment. All comparators have been accepted.
Exclusion criteria: Studies that selected participants from a population of women with systematic or
pregnancy-related health issues or who are at high risk of premature
birth.
Polyzos et al., 2010 [17 ]
Systematic review and meta-analysis
Countries of the examined studies: Studies from Chile, USA, Iran, India, Australia and Brazil.
Intervention of the examined studies: Pregnant women have been treated with scaling and root planing compared to no treatment
or prophylaxis.
Subjects: 6558 pregnant women
Exposure: Periodontal disease of the pregnant woman
Goal: To investigate whether the treatment of periodontal disease is associated with scaling
and root planing during pregnancy with a reduction in the rate of premature
births.
Primary outcome: Premature birth (< 37 weeks)
Secondary outcomes: Low birth weight (< 2500 g), spontaneous abortions/stillbirths and overall adverse
pregnancy outcomes (premature birth < 37 weeks and spontaneous
abortions/stillbirths).
Inclusion criteria: Studies in which pregnant women were treated with scaling and root planing compared
to no treatment or prophylaxis. Studies involving patients with
documented periodontal disease, regardless of the intensity and severity of the disease.
Exclusion criteria: Randomized studies that included patients at risk of premature birth who received
labor inhibitors, and non-randomized and pseudo-randomized
studies.
Moliner-Sánchez et al., 2020 [8 ]
Systematic review and meta-analysis
Countries of the examined studies: Studies from Chile, USA, Malaysia, Brazil, Madagascar, India, Canada.
Intervention of the examined studies: –
Subjects: 6768 pregnant women
Exposure: Periodontal disease of the pregnant woman
Further features: Age of subjects between 18 and 40 years, participation in the study started between
the 6th and 24th week of pregnancy.
Goal: Analyze all evidence available in the scientific literature on the risk of premature
birth and/or a low-birth-weight newborn in pregnant women with periodontal
disease.
Primary outcomes: Premature birth and/or low birth weight.
Inclusion criteria: Cohort studies analyzing the relative risk of premature birth and/or low birth weight
in pregnant women with periodontal disease. Studies that only
describe the possible correlation between these variables, as well as those in which
periodontal treatment was carried out during pregnancy. Periodontitis had to be clinically
diagnosed in the women examined during pregnancy.
Correlation between periodontal diseases, their treatment and birth outcomes
The meta-analyses and systematic reviews lead to heterogeneous results. Five of the
seven examined meta-analyses and systematic reviews [4 ]
[13 ]
[14 ]
[15 ]
[17 ] found no significant correlation between periodontal disease and/or periodontal
treatment with certain
maternal and perinatal outcomes. For example, Iheozor-Ejiofor et al. [4 ] found that there is insufficient evidence to determine which
periodontal treatment is best suited to prevent unfavorable obstetric consequences.
Konopka et al. [15 ] also explained that the
hypothesis that periodontitis is an independent risk factor for premature abortion
and/or low birth weight had to be further examined. Rosa et al. [14 ], on the other hand, found that the treatment of periodontal diseases during pregnancy
cannot offer general protection against premature birth and low birth weight.
Similar results were obtained by Boutin et al. [13 ], who found that there was no significant reduction in the risk of premature birth
due to periodontal treatment. Polyzos et al. [17 ] also confirmed this by showing that the treatment of periodontitis in pregnant women
has no significant effect on the frequency of premature births. Two of the seven meta-analyses
and systematic reviews examined, on the other hand, came to complementary results,
since they
showed correlations between periodontal diseases and certain maternal and/or perinatal
outcomes. Thus, Manrique-Corredor et al. [16 ]
found that the risk of premature birth is doubled by maternal periodontitis. Moliner-Sánchez
et al. [8 ] showed a statistically
significant correlation between periodontitis and the evaluated outcomes when the
results were examined in connection with the per capita income of the countries. A
detailed description of
the central results of the studies can be found in [Table 2 ].
Table 2
Key results of the studies.
Study
Endpoints
Results/conclusion
Iheozor-Ejiofor et al., 2017 [4 ]
No clear difference in premature births < 37 weeks (RR 0.87, 95% CI 0.70–1.10) between
periodontal treatment and no treatment. Low-quality evidence that periodontal treatment
may reduce low birth weight < 2500 g (RR 0.67, 95% CI 0.48–0.95). It is uncertain
whether periodontal treatment may result in a difference in premature birth < 35 weeks
(RR
1.19, 95% CI 0.81–1.76) and < 32 weeks (RR 1.35, 95% CI 0.78–2.32), low birth weight
< 1500 g (RR 0.80, 95% CI 0.38–1.70), perinatal mortality (including fetal and neonatal
deaths up to the first 28 days after birth) (RR 0.85, 95% CI 0.51–1.43) and preeclampsia
(RR 1.10, 95% CI 0.74–1.62).
Total included studies: 15 RCTs
Results: When comparing pregnant women with periodontal gum disease who receive treatment
to those who do not, there is no clear difference in the number of women receiving
periodontal treatment before the 37th week of pregnancy, and fewer babies may be born
weighing less than 2500 g (low-quality evidence).
Conclusion: There is insufficient evidence to determine which periodontal treatment is better
suited to prevent adverse obstetric outcomes.
Manrique-Corredor et al., 2019 [16 ]
The meta-analysis gives an OR of 2.01 (95% CI 1.71, 2.36), which represents a significant
positive correlation between the explanatory and the result variables.
Total included studies: 20 studies
Results: The risk of premature birth is doubled by maternal periodontitis.
Conclusion: Health and education centers should prioritize this risk factor and implement preventive
measures for all women of childbearing potential in order to reduce the
frequency of premature births.
Konopka et al., 2012 [15 ]
The overall odds ratio for premature birth with a low-weight infant for mothers with
periodontitis is 2.35 (1.88–2.93, p < 0.0001). For low birth weight, the total OR
is 1.5
(95% CI: 1.26–1.79, p = 0.001), for premature births −2.73 (95% CI: 2.06–3.6, p < 0.0001).
Total included studies: 15 case-control studies, 1 cross-sectional study and 6 cohorts of studies
Results: The hypothesis that periodontitis is an independent risk factor for premature termination
of pregnancy and/or low body weight in newborns needs to be further
examined.
Conclusion: Dental care for pregnant women should be established as an integral part of the prenatal
care program.
Da Rosa et al., 2012 [14 ]
Treatment of periodontal disease during pregnancy has no significant effect on the
overall birth rate of premature birth < 37 weeks (RR = 0.90, 95% CI: 0.68–1.19; p = 0.45;
I2:
74%). There is a weak correlation between the treatment of periodontal disease during
pregnancy and the reduction of low birth weight < 2500 g, and without a significant
effect
(RR = 0.92, 95% CI: 0.71–1.20; p = 0.55; I2: 56%).
Total included studies: Outcome premature births: 13 studies included; outcome low birth weight: 9 studies.
Results: Treatment of periodontal disease during pregnancy cannot provide general protection
against premature birth and low birth weight.
Conclusion: Primary periodontal treatment during pregnancy cannot reduce the rate of premature
birth or low birth weight.
Boutin et al., 2013 [13 ]
A non-significant correlation between periodontal treatment and premature birth (RR:
0.89; 95% CI: 0.73–1.08) can be determined. Daily use of chlorhexidine mouthwashes
is
associated with a reduction in premature birth rate (RR: 0.69, 95% CI 0.50–0.95).
Total included studies: 12 studies
Results: No significant reduction in the risk of premature birth due to periodontal treatment
with tartar removal (scaling) and root planing. However, the mean gestational
age and mean birth weight in the intervention groups is significantly higher than
in the comparison groups.
Conclusion: Chlorhexidine mouthwash as a preventive agent should be further examined.
Polyzos et al., 2010 [17 ]
In the high-quality studies, the treatment has no significant effect on the overall
rate of premature births (OR 1.15, 95% CI 0.95–1.40; p = 0.15). Treatment does not
result in a
reduction in the rate of low birth weight infants (OR 1.07, 0.85–1.36; p = 0.55),
spontaneous abortions/stillbirths (0.79, 0.51–1.22; p = 0.28) or overall adverse pregnancy
outcomes (premature births < 37 weeks and spontaneous abortions/stillbirths) (1.09,
0.91–1.30; p = 0.34).
Total included studies: 11 studies
Results: Treatment of periodontitis with tartar removal (scaling) and root planing in pregnant
women has no significant effect on the incidence of premature births.
Low-quality studies indicated a positive effect of the treatment, while high-quality
studies clearly show that there is no such effect.
Conclusion: Treatment of periodontal disease with tartar removal (scaling) and root planing cannot
be considered an effective means of reducing premature birth rates.
Moliner-Sánchez et al., 2020 [8 ]
Statistically significant values (RR = 1.67 [1.17–2.38], 95% CI) and low birth weight
(RR = 2.53 [1.61–3.98], 95% CI) are determined for the risk of premature birth in
pregnant
women with periodontitis. A meta-regression, in which these results are related to
the income level of the individual countries, gives statistically significant values
for
premature birth RR = 1.8 (1.43–2.27) 95% CI and for low birth weight RR = 2.9 (1.98–4.26)
95% CI. The risk of premature birth in women with periodontitis is increased by 1.67
times
and the risk of a newborn with low birth weight by 1.42 times (evidence level 2a).
Total included studies: 11 studies
Results: A statistically significant correlation between periodontitis and the two birth complications
studied is found when examining the relationship between these
results and the country’s per capita income.
Conclusion: These results may not only be due to income, but also due to other factors such as
educational attainment, and should therefore be examined in more detail in
future studies.
Evaluation of the quality of the included studies
The quality of the included meta-analyses and systematic reviews can be classified
as sufficient according to the AMSTAR checklist, resulting in an average level of
evidence. The questions
of the checklist can in some cases be answered with yes . Weaknesses in the quality of the included studies result from a priori planning/definition
(classified as Uncertain in
6 studies) as well as grey and unpublished literature included in the studies (classified
as Uncertain in all studies). Similarly, six studies present only the references of the
included studies, but not of the excluded studies. In addition, three out of seven
studies do not provide information on a potential conflict of interest. All other
seven questions of the
checklist could be consistently assessed as yes in all included studies. The results of this evaluation are shown in [Table 3 ].
Table 3
Evaluation of the quality of the included studies according to the AMSTAR checklist.
Study
A priori planning/definition
Study selection/extraction of 2 independent persons
Comprehensive systematic literature search
Unpublished and grey literature included
References of the included and excluded literature
Study characteristics indicated
Risk of distortion assessed
Risk of distortion taken into account in the interpretation of results
Statistically adequate evaluation
Potential publication bias addressed
Potential conflicts of interest addressed
Iheozor-Ejiofor et al., 2017 [4 ]
Yes
Yes
Yes
Uncertain
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Manrique-Corredor et al., 2019 [16 ]
Uncertain
Yes
Yes
Uncertain
No
Yes
Yes
Yes
Yes
Yes
Yes
Konopka et al., 2012 [15 ]
Uncertain
Yes
Yes
Uncertain
No
Yes
Yes
Yes
Yes
Yes
No
Da Rosa et al., 2012 [14 ]
Uncertain
Yes
Yes
Uncertain
Yes
Yes
Yes
Yes
Yes
Yes
No
Boutin et al., 2013 [13 ]
Uncertain
Yes
Yes
Uncertain
No
Yes
Yes
Yes
Yes
Yes
No
Polyzos et al., 2010 [17 ]
Uncertain
Yes
Yes
Uncertain
No
Yes
Yes
Yes
Yes
Yes
Yes
Moliner-Sánchez et al., 2020 [8 ]
Uncertain
Yes
Yes
Uncertain
No
Yes
Yes
Yes
Yes
Yes
Yes
Discussion
Summary of results
A total of seven meta-analyses and systematic reviews [4 ]
[8 ]
[13 ]
[14 ]
[15 ]
[16 ]
[17 ] were included in the narrative review (n = 56755). The examined studies of
the meta-analyses and systematic reviews used periodontal treatment vs. no treatment
as an intervention, or they investigated the correlation between periodontal diseases
and negative birth
results. The studies came to heterogeneous results, whereby the majority of the examined
meta-analyses and systematic reviews [4 ]
[13 ]
[14 ]
[15 ]
[17 ] do not find a significant correlation between periodontal disease and/or periodontal
treatment with certain maternal and/or perinatal
outcomes. A medium level of evidence may be assumed based on the AMSTAR assessment.
Embedding in the state of research
Periodontal diseases are discussed as a risk factor for premature births and/or low
birth weight. Nevertheless, there is little consensus on the extent to which periodontal
treatment in
pregnancy can prevent or reduce negative birth outcomes [14 ]. However, most of the studies included here did not confirm the
correlation between periodontal health and risk of premature birth or risk of negative
maternal or perinatal outcomes. It should be noted that only two of the seven meta-analyses
examined
indicated significant correlations with regard to an increase in risk in the case
of deficient oral health [8 ]
[16 ]. Both studies were published in 2019 and 2020, and were therefore younger than those
meta-analyses (including the included Cochrane
review [4 ]), which did not postulate any significant correlations. For the benefit of periodontal
treatment in terms of risk reduction
for premature birth and negative outcomes, there was no clear evidence of efficacy
[13 ]
[14 ]
[17 ]. According to the AMSTAR assessment, a medium quality is indicated for all included
studies, so whether
oral health influences the risk of premature birth or the risk of negative outcomes
cannot be conclusively assessed.
Other reviews arrive at similar results: Teshome and Yitayeh also conducted a systematic
review, which analyzed the correlation between periodontal disease and low premature
birth weight.
It was found that periodontal disease could be a possible risk factor for premature
births with low birth weight, but further studies would be necessary [18 ]. Ide and Papapanou also show that maternal periodontitis is slightly but significantly
related to low birth weight and premature
birth. However, the results are influenced by the exposure definition of periodontitis
[19 ]. The same can be found in the present
narrative review. The heterogeneity of the classifications of the severity of periodontal
disease causes difficulties, both in the meta-analyses and systematic reviews themselves,
as well as
in the studies considered therein. López et al. also reported something similar in
a review. They found that those people included in studies who showed a positive effect
of the treatment of
periodontitis on premature birth were not based on consistent scientific findings
[20 ]. Rangel-Rincón et al. also showed in their
review that the different findings are not sufficient to demonstrate that the frequency
of undesirable pregnancy outcomes in pregnant women receiving periodontal treatment
decreases
significantly [21 ].
It should also be noted that premature birth and other outcomes considered here represent
multifactorial events. Risk factors such as smoking, low socio-economic status, maternal
age and
ethnicity can promote both periodontitis and premature birth. This can lead to misinterpretation
of the data, as there may be no causal relationship between the outcomes examined
and
periodontitis [4 ]. The results of this narrative review underline the results of some systematic reviews,
which focus on the same topic.
There is insufficient evidence to conclusively assess the correlation between periodontal
disease and negative birth outcomes.
Limitations
The present study also showed some limitations, which resulted, on the one hand, from
the methodological approach and, on the other hand, from the included studies. One
limitation was that
only English-language articles were included in the review, which can lead to distortion.
Despite the independent search of three authors, it remains uncertain whether all
relevant studies
could really be identified. With regard to the limitations of the included studies,
reference should be made to the heterogeneity of the included meta-analyses and systematic
reviews. This
was calculated in all meta-analyses, which in some cases led to significant values
and considerably restricted the comparability of the results. Many of the meta-analyses
examined here also
demonstrate publication distortion. In addition, there is no consensus about which
time of the dental examination is considered suitable in pregnancy [4 ]. It is also critical to note that in some studies, subjects who have experienced
premature birth were also included during a previous birth, which was insufficiently
taken into account in the examinations from a statistical standpoint [4 ]. In addition, the periodontal treatments in the studies are
very diverse, which makes comparability difficult. The meta-analyses and systematic
reviews also include different study designs. For example, in some papers, only randomized
studies were
considered [4 ]
[13 ]
[14 ]
[17 ], while others also included observational studies [8 ]
[15 ]
[16 ]. It should also be noted that some of the
included meta-analyses partially evaluated the same studies. However, the meta-analyses
each examine further, differing studies, which is why these were nevertheless included
separately in
this narrative review. It should be noted that Polyzos et al. [17 ] and Boutin et al. [13 ] investigated similar studies and presented similar results. Despite the limitations,
the results outlined here can be described as an extension of the state of
research due to the overall high total number of subjects (n = 56755) and the inclusion
criterion of the meta-analyses and systematic reviews.
Answering the research questions
Based on the results, the above research questions can be answered as follows:
How can the correlation between periodontal disease in pregnant women and pregnancy
complications be assessed using meta-analyses and systematic reviews? Periodontitis as a risk
factor for premature birth must be further examined, since heterogeneous study results
are available, some of them of inadequate quality. However, one of the examined studies
indicates
that the risk of premature birth doubles in the presence of maternal periodontitis
[16 ]. Another examined study shows a significant
correlation between periodontitis and certain maternal and perinatal outcomes when
the results are analyzed in relation to the countries’ per capita income [8 ]. Here, however, it remains uncertain whether periodontitis really has an influence
on the risk of premature birth, or an existing
low socio-economic status, which as a risk factor influences both the risk of premature
birth and the risk of poor dental health [22 ]
[23 ].
How can the efficacy of periodontal treatment vs. no treatment in pregnant women with
periodontal disease be assessed in terms of premature birth and other negative birth
outcomes
(see definition below) using meta-analyses and systematic reviews? The majority of the examined meta-analyses and systematic reviews show that there
is no significant correlation
between periodontal treatment and certain maternal and perinatal outcomes [4 ]
[13 ]
[14 ]
[17 ]. There is insufficient evidence [4 ] to determine which periodontal treatment is best suited to avoid negative obstetric
consequences. Periodontal treatment during
pregnancy does not significantly reduce the risk or frequency of premature birth [13 ]
[14 ]
[17 ] and low birth weight [14 ].
Conclusion
Most of the included studies indicate that there is no significant correlation between
dental health and the risk of premature birth or negative maternal and perinatal outcomes
or between
periodontal treatments during pregnancy and the reduction of the risk of premature
birth. However, the quality of the studies is not high enough to be able to record
this with a high level of
evidence. To improve the evidence level, further randomized controlled trials must
be conducted to systematically control the bias. Nevertheless, it is recommended that
all pregnant women be
advised to improve daily oral hygiene, so that this is promoted and inflammatory diseases
can be counteracted by preventive efforts. This should be a routine part of health
advice,
irrespective of pregnancy. In the context of a benefit/harm assessment, the treatment
of periodontitis based on an individualized risk assessment is recommended in pregnant
women, since in
many cases periodontal treatment leads to an improvement in periodontal health. Since,
as part of the reformulation of the German Midwifery Act, midwives will also be asked
to provide
evidence-based advice and care in future, the results of the present paper are equally
relevant for both gynecologists and midwives [24 ].
