***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objectives The aim of this study was to evaluate the effects of non-surgical treatment of periodontal disease during the second trimester of gestation on adverse pregnancy outcomes . Material and Methods Pregnant patients during the 1st and 2nd trimesters at antenatal care in a Public Health Center were divided into 2 groups : NIG – " no intervention " ( n=17 ) or IG- " intervention " ( n=16 ) . IG patients were su bmi tted to a non-surgical periodontal treatment performed by a single periodontist consisting of scaling and root planning ( SRP ) , professional prophylaxis ( PROPH ) and oral hygiene instruction ( OHI ) . NIG received PROPH and OHI during pregnancy and were referred for treatment after delivery . Periodontal evaluation was performed by a single trained examiner , blinded to periodontal treatment , according to probing depth ( PD ) , clinical attachment level ( CAL ) , plaque index ( PI ) and sulcular bleeding index ( SBI ) at baseline and 35 gestational weeks-28 days post-partum . Primary adverse pregnancy outcomes were preterm birth ( < 37 weeks ) , low birth weight ( < 2.5 kg ) , late abortion ( 14 - 24 weeks ) or abortion ( < 14 weeks ) . The results obtained were statistically evaluated according to OR , unpaired t test and paired t test at 5 % significance level . Results No significant differences were observed between groups at baseline examination . Periodontal treatment result ed in stabilization of CAL and PI ( p>0.05 ) at IG and worsening of all periodontal parameters at NIG ( p<0.0001 ) , except for PI . Significant differences in periodontal conditions of IG and NIG were observed at 2nd examination ( p<0.001 ) . The rate of adverse pregnancy outcomes was 47.05 % in NIG and 6.25 % in IG . Periodontal treatment during pregnancy was associated to a decreased risk of developing adverse pregnancy outcomes [ OR=13.50 ; CI : 1.47 - 123.45 ; p=0.02 ] . Conclusions Periodontal treatment during the second trimester of gestation contributes to decrease adverse pregnancy outcomes Several European countries have guidelines suggesting that women should not receive mercury-containing dental amalgam fillings  during pregnancy . One concern raised by several studies is that mercury exposure during pregnancy may lead to decreased birth weight . A population -based , case-control study was design ed to investigate whether placement of mercury-containing fillings in 1993 - 2000 during pregnancy increased the low-birth-weight risk . Cases and controls were sample d from enrollees of a dental insurance plan with live singleton births in Washington State ; 1,117 women with low-birth-weight infants ( < 2,500 g ) were compared with a r and om sample of 4,468 women with infants weighing 2,500 g or more . The results indicated that 13 % of a dentally insured population had one or more restorative procedures during pregnancy that , regardless of chemical composition , did not increase the low-birth-weight risk ( odds ratio = 0.96 , 95 % confidence interval : 0.88 , 1.05 ) . The 4.9 % of the women ( n = 249 ) who had at least one mercury-containing amalgam filling during pregnancy were not at an increased risk for a low-birth-weight infant ( odds ratio = 0.75 , 95 % confidence interval : 0.45 , 1.26 ) and neither were women who had 4 - 11 amalgam fillings placed ( odds ratio = 1.00 , 95 % confidence interval : 0.27 , 3.68 ) . This study found no evidence that mercury-containing dental fillings placed during pregnancy increased low-birth-weight risk Oral Conditions and Pregnancy ( OCAP ) is a 5-year prospect i ve study of pregnant women design ed to determine whether maternal periodontal disease contributes to the risk for prematurity and growth restriction in the presence of traditional obstetric risk factors . Full-mouth periodontal examinations were conducted at enrollment ( prior to 26 weeks gestational age ) and again within 48 hours postpartum to assess changes in periodontal status during pregnancy . Maternal periodontal disease status at antepartum , using a 3-level disease classification ( health , mild , moderate-severe ) as well as incident periodontal disease progression during pregnancy were used as measures of exposures for examining associations with the pregnancy outcomes of preterm birth by gestational age ( GA ) and birth weight ( BW ) adjusting for race , age , food stamp eligibility , marital status , previous preterm births , first birth , chorioamnionitis , bacterial vaginosis , and smoking . Interim data from the first 814 deliveries demonstrate that maternal periodontal disease at antepartum and incidence/progression of periodontal disease are significantly associated with a higher prevalence rate of preterm births , BW < 2,500 g , and smaller birth weight for gestational age . For example , among periodontally healthy mothers the unadjusted prevalence of births of GA < 28 weeks was 1.1 % . This was higher among mothers with mild periodontal disease ( 3.5 % ) and highest among mothers with moderate-severe periodontal disease ( 11.1 % ) . The adjusted prevalence rates among GA outcomes were significantly different for mothers with mild periodontal disease ( n = 566 ) and moderate-severe disease ( n = 45 ) by pair-wise comparisons to the periodontally healthy reference group ( n = 201 ) at P = 0.017 and P < 0.0001 , respectively . A similar pattern was seen for increased prevalence of low birth weight deliveries among mothers with antepartum periodontal disease . For example , there were no births of BW < 1000 g among periodontally healthy mothers , but the adjusted rate was 6.1 % and 11.4 % for mild and moderate-severe periodontal disease ( P = 0.0006 and P < 0.0001 ) , respectively . Periodontal disease incidence/progression during pregnancy was associated with significantly smaller births for gestational age adjusting for race , parity , and baby gender . In summary , the present study , although preliminary in nature , provides evidence that maternal periodontal disease and incident progression are significant contributors to obstetric risk for preterm delivery , low birth weight and low weight for gestational age . These studies underscore the need for further consideration of periodontal disease as a potentially new and modifiable risk for preterm birth and growth restriction OBJECTIVE : To investigate whether treating periodontal disease prevents preterm birth and other major complications of pregnancy . METHODS : This single-center trial was conducted across six obstetric sites in metropolitan Perth , Western Australia . Pregnant women identified by history to be at risk ( n=3,737 ) were examined for periodontal disease . Approximately 1,000 women with periodontal disease were allocated at r and om to receive periodontal treatment commencing around 20 weeks of gestation ( n=542 ) or 6 weeks after the pregnancy was completed ( controls ; n=540 ) . The treatment included mechanical removal of oral biofilms together with oral hygiene instruction and motivation at a minimum of three weekly visits , with further visits if required . RESULTS : There were no differences between the control and treatment groups in preterm birth ( 9.3 % compared with 9.7 % , odds ratio [ OR ] 1.05 , 95 % confidence interval [ CI 0.7–1.58 ] , P=.81 ) , birth weight ( 3,450 compared with 3,410 g , P=.12 ) , preeclampsia ( 4.1 % compared with 3.4 % , OR 0.82 , 95 % CI 0.44–1.56 , P=.55 ) , or other obstetric endpoints . There were four unexplained stillbirths in the control group and no pregnancy losses in the treated group ( P=.12 ) . Measures of fetal and neonatal well-being were similar in the two groups , including abnormalities in fetal heart rate recordings ( P=.26 ) , umbilical artery flow studies ( P=.96 ) , and umbilical artery blood gas values ( P=.37 ) . The periodontal treatment was highly successful in improving health of the gums ( P<.01 ) . CONCLUSION : The evidence provided by the present study does not support the hypothesis that treatment of periodontal disease during pregnancy in this population prevents preterm birth , fetal growth restriction , or preeclampsia . Periodontal treatment was not hazardous to the women or their pregnancies . CLINICAL TRIAL REGISTRATION : Clinical Trials.gov , www . clinical trials.gov , NCT00133926 . LEVEL OF EVIDENCE : OBJECTIVE The purpose of this study was to test whether treating periodontal disease ( PD ) in pregnancy will reduce the incidence of spontaneous preterm delivery ( SPTD ) at < or = 35 weeks of gestation . STUDY DESIGN A multicenter , r and omized clinical trial was performed . Subjects with PD were r and omized to scaling and root planing ( active ) or tooth polishing ( control ) . The primary outcome was the occurrence of SPTD at < 35 weeks of gestation . RESULTS We screened 3563 subjects for PD ; the prevalence of PD was 50 % . Seven hundred fifty-seven subjects were assigned r and omly ; 378 subjects were assigned to the active group , and 379 subjects were assigned to the placebo group . Active treatment did not reduce the risk of SPTD at < 35 weeks of gestation ( relative risk , 1.19 ; 95 % confidence interval [ CI ] , 0.62 - 2.28 ) or composite neonatal morbidity ( relative risk , 1.30 ; 95 % CI , 0.83 - 2.04 ) . There was a suggestion of an increase in the risk of indicated SPTD at < 35 weeks of gestation in those subjects who received active treatment ( relative risk , 3.01 ; 95 % CI , 0.95 - 4.24 ) . CONCLUSION Treating periodontal disease does not reduce the incidence of SPTD 
    Output:
    
From this review it can be concluded that most dental work is safe during pregnancy .