Effect of periodontal treatment on preterm birth rate: a systematic review of meta-analyses.

Preterm birth is a major cause of neonatal morbidity and mortality in both developed and developing countries. Preterm birth is a highly complex syndrome that includes distinct clinical subtypes in which many different causes may be involved. The results of epidemiological, molecular, microbiological and animal-model studies support a positive association between maternal periodontal disease and preterm birth. However, the results of intervention studies carried out to determine the effect of periodontal treatment on reducing the risk of preterm birth are controversial. This systematic review critically analyzes the methodological issues of meta-analyses of the studies to determine the effect of periodontal treatment to reduce preterm birth. The quality of the individual randomized clinical trials selected is of highest relevance for a systematic review. This article describes the methodological features that should be identified a priori and assessed individually to determine the quality of a randomized controlled trial performed to evaluate the effect of periodontal treatment on pregnancy outcomes. The AMSTAR and the PRISMA checklist tools were used to assess the quality of the six meta-analyses selected, and the bias domain of the Cochrane Collaboration's Tool was applied to evaluate each of the trials included in the meta-analyses. In addition, the methodological characteristics of each clinical trial were assessed. The majority of the trials included in the meta-analyses have significant methodological flaws that threaten their internal validity. The lack of effect of periodontal treatment on preterm birth rate concluded by four meta-analyses, and the positive effect of treatment for reducing preterm birth risk concluded by the remaining two meta-analyses are not based on consistent scientific evidence. Well-conducted randomized controlled trials using rigorous methodology, including appropriate definition of the exposure, adequate control of confounders for preterm birth and application of effective periodontal interventions to eliminate periodontal infection, are needed to confirm the positive association between periodontal disease and preterm birth.

Routine prophylaxes every 3 months improves chronic periodontitis status in type 2 diabetes.

BACKGROUND: Periodontitis and type 2 diabetes mellitus (T2DM) are major health problems, especially in low-income populations with little access to dental care. Low-cost models for treatment of periodontal disease have not been tested in controlled studies in low-income populations. Dental prophylaxis, which includes removal of supragingival calculus and plaque, has been shown to arrest the progression of periodontitis. A controlled clinical trial was conducted to determine the effect of dental prophylaxis on periodontitis in T2DM. METHODS: Twenty-six patients with T2DM and chronic periodontitis (CP) and 26 without T2DM with CP were selected. Periodontal probing depth (PD), gingival bleeding on probing (BOP), clinical attachment level (CAL), and surfaces with plaque were recorded at baseline and 3, 6, and 9 months after initial treatment. All the participants received instructions on oral hygiene and one session of dental prophylaxis at baseline and every 3 months. Glycated hemoglobin (HbA1c) levels were measured at baseline and every 3 months in patients with T2DM. RESULTS: A significant improvement of PD, BOP, and sites with plaque was observed 3 months after treatment in patients with T2DM (P = 0.001). In controls, mean PD significantly improved after 6 months compared with baseline (P = 0.001). No significant improvement of CAL occurred in either group. No significant differences in periodontal parameters between the groups were detected, and no participant showed progression of CP during the 9-month study period. Dental prophylaxis did not influence HbA1c levels, and no association among HbA1c concentration, pretreatment metabolic status, and severity of CP was found. CONCLUSION: Routine prophylaxes every 3 months significantly improve periodontal health and prevent progression of CP in both poorly controlled and well-controlled patients with T2DM.

Effects of periodontal therapy on systemic markers of inflammation in patients with metabolic syndrome: a controlled clinical trial.

BACKGROUND: The systemic inflammation in both metabolic syndrome (MetS) and periodontitis is a common denominator of the association of these conditions with higher risk of atherosclerosis. The current study investigates whether periodontal therapy may reduce systemic inflammation in patients with MetS and reduce cardiovascular risk. METHODS: A parallel-arm, double-blind, randomized clinical trial of 1-year duration in patients with MetS and periodontitis was conducted. Participants were randomized to an experimental treatment group (ETG) (n = 82) that received plaque control and root planing plus amoxicillin and metronidazole or to a control treatment group (CTG) (n = 83) that received plaque control instructions, supragingival scaling, and two placebos. Risk factors for cardiovascular disease were recorded; serum lipoprotein cholesterol, glucose, body mass index (BMI), C-reactive protein (CRP) and fibrinogen concentrations, and clinical periodontal parameters were assessed at baseline and every 3 months until 12 months after therapy. The primary and secondary outcomes were changes in CRP and fibrinogen levels, respectively. RESULTS: The baseline patients' characteristics of both groups were similar. No significant changes in lifestyle factors, frequency of hypertension, BMI, serum lipoprotein cholesterol, and glucose levels were observed during the study period. The periodontal parameters significantly improved in both groups 3 months after therapy (P = 0.0001) and remained lower than baseline up to 12 months. The improvement of periodontal status was significantly greater in the ETG (P = 0.0001). A multiple linear regression analysis, controlled for sex, smoking, hypertension, and extent of periodontitis, demonstrated that CRP levels decreased with time and that this reduction was significant at 9 (P = 0.024) and 12 (P = 0.001) months in both groups, without difference between the groups. Fibrinogen levels significantly decreased in the ETG at 6 and 12 months but not in the CTG. CONCLUSION: Reduction of periodontal inflammation either with root planing and systemic antibiotics or with plaque control and subgingival scaling significantly reduces CRP levels after 9 months in patients with MetS.

[Association between atherosclerosis and periodontitis]. / Aterosclerosis en sujetos con periodontitis.

BACKGROUND: Chronic inflammation and infections are involved in the development and progression of atherosclerotic vascular disease. AIM: To evaluate the association between periodontitis and early atherosclerosis. MATERIAL AND METHODS: Fifty-three subjects who received periodontal treatment and regular maintenance for at least 10 years, and 55 subjects with periodontitis but without a history of periodontal treatment were studied. Carotid artery intima-media wall thickness (CIMT) was measured with high-resolution B-mode ultrasonography. A blood sample was obtained to measure high sensitivity C-reactive protein, fibrinogen, lipoprotein cholesterol, leukocyte count and erythrocyte sedimentation rate. Covariates included age, gender, smoking, level of education, body mass index and physical activity. The benzoyl-DL-arginine-naphthylamide (BANA) test was used to determine the number of periodontal sites with periodontal pathogens. RESULTS: CIMT value was significantly higher in subjects with periodontitis than those without it (0.775 ± 0.268 and 0.683 ± 0.131 mm respectively, p = 0.027). C-reactive protein, leukocyte count and percentage of sites with periodontal pathogens were also significantly higher in subjects with periodontitis. Regression analysis identified age, periodontitis, and smoking as independent predictors of CIMT. CONCLUSIONS: These results suggest that untreated periodontitis is associated with early atherosclerotic carotid lesions and higher levels of inflammatory markers.

Aterosclerosis en sujetos con periodontitis / Association between atherosclerosis and periodontitis

Background: Chronic infl ammation and infections are involved in the development and progression of atherosclerotic vascular disease. Aim: To evaluate the association between periodontitis and early atherosclerosis. Material and Methods: Fifty-three subjects who received periodontal treatment and regular maintenance for at least 10 years, and 55 subjects with periodontitis but without a history of periodontal treatment were studied. Carotid artery intima-media wall thickness (CIMT) was measured with high-resolution B-mode ultrasonography. A blood sample was obtained to measure high sensitivity C-reactive protein, fibrinogen, lipoprotein cholesterol, leukocyte count and erythrocyte sedimentation rate. Covariates included age, gender, smoking, level of education, body mass index and physical activity. The benzoyl-DL-arginine-naphthylamide (BANA) test was used to determine the number of periodontal sites with periodontal pathogens. Results: CIMT value was significantly higher in subjects with periodontitis than those without it (0.775 ± 0.268 and 0.683 ± 0.131 mm respectively, p = 0.027). C-reactive protein, leukocyte count and percentage of sites with periodontal pathogens were also significantly higher in subjects with periodontitis. Regression analysis identified age, periodontitis, and smoking as independent predictors of CIMT. Conclusions: These results suggest that untreated periodontitis is associated with early atherosclerotic carotid lesions and higher levels of infl ammatory markers.

[Effects of periodontal therapy on markers of systemic inflammation in patients with coronary heart disease risk]. / Efectos del tratamiento periodontal sobre los marcadores de inflamación sistémica en pacientes con riesgo de enfermedad cardiaca coronaria. Estudio piloto.

BACKGROUND: Studies investigating effects of periodontal treatment (PT) on markers of inflammation in healthy subjects show conflicting results. Few studies have investigated the effects of PT among subjects with coronary heart disease (CHD) risk factors. AIM: To report the results of a pilot prospective study on the effects of periodontal treatment on markers of inflammation among subjects with CHD risk factors. MATERIAL AND METHODS: Seventy three patients aged 53+/-6 years (25% males) with chronic periodontitis, dyslipidemia and other CHD risk factors were subjected to PT consisting on root planning and oral metronidazol and amoxicillin for 7 days. Periodontal clinical parameters, serum C-reactive protein (CRP), fibrinogen levels and erythrocyte sedimentation rate (ESR) were assessed before and at 6 weeks after PT. Polymorphisms at the ILlA-889 and IL1B+3954 genes were also genotyped. RESULTS: After the treatment period, CRP levels significantly increased from 3.6+/-3.7 mg/ L to 5.4+/-5.7 mg/L (p =0.001). No significant changes were observed in fibrinogen levels and ESR. Higher post-treatment CRP levels were significantly associated with the composite polymorphic genotype at the ILlA-889 and IL1B+3954 genes (p =0.0001), and extensive periodontitis (p =0.005). Moderate alcohol consumption appeared as a protective factor for CRP elevation (p =0.029). CONCLUSIONS: The increase of the CRP levels after PT in patients with CVD risk factors appeared associated with IL-1 gene polymorphisms and extensive periodontitis.

Interleukin-1 gene cluster polymorphisms associated with periodontal disease in type 2 diabetes.

BACKGROUND: Epidemiologic studies have shown an increased frequency, severity, and risk of periodontitis in patients with diabetes. Periodontitis is associated with certain interleukin (IL)-1 gene cluster polymorphisms. Diabetes is a proinflammatory state with increased levels of circulating cytokines suggesting a causal role for inflammation in its etiology. Common genetic factors may be involved in the susceptibility for diabetes and periodontitis. We evaluated the relationships among IL-1 gene polymorphisms, type 2 diabetes, and periodontitis. METHODS: One hundred twelve patients with diabetes and chronic periodontitis, 224 patients without diabetes but with chronic periodontitis, and 208 healthy subjects without periodontitis were studied. All received a clinical periodontal examination and assessment of standard periodontal parameters. IL-1A -889, -1B +3954, and -1B -511 polymorphisms were identified by polymerase chain reaction (PCR) amplification followed by restriction enzyme digestion and gel electrophoresis. Variable numbers of IL-1RN tandem repeats were detected by PCR amplification and fragment-size analysis. RESULTS: The severity and extent of periodontitis was significantly greater in patients with diabetes than in patients without diabetes. No significant differences in IL-1A -899, -1B +3954, or -1RN genotype frequencies were found between patients with diabetes and patients without diabetes. The IL-1A -889 TT genotype (odds ratio [OR] = 2.90; 95% confidence interval [CI] = 1.20 to 7.02), IL-1B +3954 TT genotype (OR = 3.54; 95% CI = 1.15 to 10.85), and IL-1B -511 CC genotype (OR = 2.10; 95% CI = 1.25 to 3.58) were significantly associated with periodontitis. The presence of an IL-1 positive genotype was significantly associated with periodontitis (OR = 1.61; 95% CI = 1.04 to 2.49). No interaction between smoking status and polymorphisms was found. CONCLUSIONS: Periodontitis was significantly associated with some IL-1 gene polymorphisms. No association between diabetes and IL-1A and -1B gene polymorphisms was found.

Efectos del tratamiento periodontal sobre los marcadores de inflamación sistémica en pacientes con riesgo de enfermedad cardiaca coronaria: Estudio piloto / Effects of periodontal therapy on markers of systemic inflammation in patients with coronary heart disease risk

Background- Studies investigating effects of periodontal treatment (PT) on markers of inflammation in healthy subjects show conflicting results. Few studies have investigated the effects ofPT among subjects with coronary heart disease (CHD) risk factors. Aim: To report the results of a pilot prospective study on the effects of periodontal treatment on markers of inflammation among subjects with CHD risk factors. Material and methods: Seventy three patients aged 53±6 years (25 percent males) with chronic periodontitis, dyslipidemia and other CHD risk factors were subjected to PT consisting on root planning and oral metronidazol and amoxicillin for 7 days. Periodontal clinical parameters, serum C-reactive protein (CRP), fibrinogen levels and erythrocyte sedimentation rate (ESR) were assessed before and at 6 weeks añerPT. Polymorphisms at the ILlA-889 andIL1B+3954genes were also genotyped. Results: After the treatment period, CRP levels significantly increased from 3.6±3.7 mg/ L to 5.4±5.7 mg/L (p =0.001). No significant changes were observed in fibrinogen levels and ESR. Higher post-treatment CRP levels were significantly associated with the composite polymorphic genotype at the ILlA-889 and IL1B+3954 genes (p =0.0001), and extensive periodontitis (p =0.005). Moderate alcohol consumption appeared as a protective factor for CRP elevation (p =0.029). Conclusions: The increase of the CRP levels after PT in patients with CVD risk factors appeared associated with IL-1 gene polymorphisms and extensive periodontitis.

Effects of metronidazole plus amoxicillin as the only therapy on the microbiological and clinical parameters of untreated chronic periodontitis.

AIM: To determine the effect of metronidazole plus amoxicillin (M+A) as the sole therapy, on the subgingival microbiota of chronic periodontitis. MATERIAL AND METHODS: Twenty-two patients with untreated chronic periodontitis were randomly assigned to a group that received M+A for 7 days, or to a group receiving scaling and root planing (SRP) and two placebos. Clinical measurements including sites with plaque, bleeding on probing (BOP), probing depth (PD) and attachment level (AL) were made at baseline, 3, 6, 9 and 12 months. Subgingival plaque samples were taken from all teeth at baseline 3, 6, 9 and 12 months for the counts of 40 subgingival species using checkerboard DNA-DNA hybridization. RESULTS: Mean PD was reduced from 2.80+/-0.45 at baseline to 1.95+/-0.05 at 12 months (P<0.001) and from 2.39+/-0.41 to 1.95+/-0.10 (P<0.001) in the M+A- and SRP-treated patients, respectively. Corresponding values for relative mean AL were 10.07+/-1.30-9.77+/-0.34 (P<0.001) and 9.94+/-0.28-9.77+/-0.26 (P<0.001). Percentage of sites exhibiting BOP were 40.6+/-18.3-14.0+/-1.4 (P<0.001), and 38.5+/-5.1-19.0+/-2.8 (P<0.001) in the M+A and SRP groups, respectively. Mean total DNA probe counts and counts of the majority of the 40 test species were significantly reduced over time in both groups, with no significant differences detected at any time point between groups. At 12 months many of the species were still present at significantly lowered levels compared with their baseline counts in both groups. CONCLUSIONS: Changes in clinical and microbiological parameters were similar after receiving systemically administered M+A as the sole therapy or after receiving SRP only.

Periodontal therapy reduces the rate of preterm low birth weight in women with pregnancy-associated gingivitis.

BACKGROUND: One hypothesis to explain the association between periodontal disease (PD) preterm/low birth weight (PT/LBW) is that PT/LBW may be indirectly mediated through translocation of bacteria or bacterial products in the systemic circulation. Transient bacteremias occur in subjects with marginal periodontitis or with gingivitis, and it is possible that bacteria and their products may reach the placental membranes hematogenously and provide the inflammatory effect to induce preterm labor. The effect of gingivitis as a potential risk factor for PT/LBW has still not been studied. A randomized controlled trial was undertaken to determine the effect of routine plaque control and scaling on the pregnancy outcomes in women with gingivitis. METHODS: Eight hundred seventy (870) pregnant women with gingivitis, aged 18 to 42, were enrolled while receiving prenatal care in Santiago, Chile. Women were randomly assigned in a two-to-one fashion to either a treatment group (N = 580), receiving periodontal treatment before 28 weeks of gestation or to a control group (N = 290), receiving periodontal treatment after delivery. Periodontal therapy consisted of plaque control, scaling, and daily rinsing with 0.12% clorhexidine. Maintenance therapy was provided every 2 to 3 weeks until delivery, and consisted of oral hygiene instruction and supragingival plaque removal by instrumentation, as needed. The primary outcomes assessed were delivery at less than 37 weeks of gestation or an infant weighing less than 2,500 g. RESULTS: Of the 870 women enrolled, 36 women (27 in the treatment group and nine in the control group) were excluded from the analyses for different reasons. The incidence of PT/LBW in the treatment group was 2.14% (12/560) and in the control group, 6.71% (19/283) (odds ratio [OR] 3.26; 95% confidence interval [CI] 1.56 to 6.83; P = 0.0009). Multivariate logistic regression analysis showed that, after adjusting for several known risk factors for PT/LBW, women with gingivitis were at a higher risk of PT/LBW than women who received periodontal treatment (OR 2.76; 95%CI 1.29 to 5.88; P = 0.008). CONCLUSIONS: Periodontal treatment significantly reduced the PT/LBW rate in this population of women with pregnancy-associated gingivitis. Within the limitations of this study, we conclude that gingivitis appears to be an independent risk factor for PT/LBW for this population.

Association of interleukin-1 polymorphisms with periodontal disease.

BACKGROUND: Several studies have investigated genetic polymorphisms for cytokines as potential genetic markers for periodontitis. Some studies have found that interleukin (IL)-1A and IL-1B polymorphisms are associated with a higher severity of periodontitis, while others found no association. The aims of this study were to determine the prevalence of the IL-1A-889 and IL-1B+3954 (previously described as +3953) polymorphisms in Chileans and their association with periodontitis. METHODS: Subjects aged 20 to 48 were selected from people requesting dental treatment at a public health center in Santiago, Chile. A case-control study of 330 cases of periodontitis patients and 101 healthy controls was performed. A full-mouth periodontal examination was performed on each subject and a structured questionnaire was conducted to determine smoking habits. Cases were categorized as having initial, moderate, or severe periodontitis according to the percentage of sites with clinical attachment loss > or =3 mm. Genomic DNA was analyzed for polymorphism in the IL-1A gene at site -889 and IL-1B gene at site +3954 by polymerase chain reaction (PCR) amplification followed by restriction enzyme digestion and gel electrophoresis. Data were analyzed by chi square test, analysis of variance (ANOVA), and by calculating odds ratio (OR) and 95% confidence intervals (CI). RESULTS: Demographic and socio-economic characteristics of subjects were similar in cases and in controls. A higher frequency of heterozygous of the IL-1A-889 was found in cases than in controls, but the difference was not significant. The heterozygous of the IL-1B+3954 was significantly higher in cases than in controls and was associated with periodontitis (OR 3.12, 95% CI 1.59 to 6.09, P = 0.001). The homozygous for allele 1 of the IL-1B+3954 was a protective factor for periodontitis (OR 0.35, 95% CI 0.19 to 0.66, P = 0.001). The prevalence of positive genotype (at least one allele 2 present at each locus) was significantly higher in cases (26.06%) than in controls (9.9%) and was significantly associated with periodontitis (OR 3.21, 95% CI 1.60 to 6.44, P = 0.001), irrespective of the smoking status and periodontitis severity. Sensitivity of positive genotype was 26%, the specificity 90%, and the positive predictive value 89%. CONCLUSION: Within the limits of this study, the results show that individuals carrying the positive genotype have significantly greater risk for developing periodontitis.

Periodontal Therapy Reduces the Rate of Preterm Low Birth Weight in Women With Pregnancy-Associated Gingivitis.

BACKGROUND: One hypothesis to explain the association between periodontal disease (PD) preterm/low birth weight (PT/LBW) is that PT/LBW may be indirectly mediated through translocation of bacteria or bacterial products in the systemic circulation. Transient bacteremias occur in subjects with marginal periodontitis or with gingivitis, and it is possible that bacteria and their products may reach the placental membranes hematogenously and provide the inflammatory effect to induce preterm labor. The effect of gingivitis as a potential risk factor for PT/LBW has still not been studied. A randomized controlled trial was undertaken to determine the effect of routine plaque control and scaling on the pregnancy outcomes in women with gingivitis. METHODS: Eight hundred seventy (870) pregnant women with gingivitis, aged 18 to 42, were enrolled while receiving prenatal care in Santiago, Chile. Women were randomly assigned in a two-to-one fashion to either a treatment group (N = 580), receiving periodontal treatment before 28 weeks of gestation or to a control group (N = 290), receiving periodontal treatment after delivery. Periodontal therapy consisted of plaque control, scaling, and daily rinsing with 0.12% clorhexidine. Maintenance therapy was provided every 2 to 3 weeks until delivery, and consisted of oral hygiene instruction and supragingival plaque removal by instrumentation, as needed. The primary outcomes assessed were delivery at less than 37 weeks of gestation or an infant weighing less than 2,500 g. RESULTS: Of the 870 women enrolled, 36 women (27 in the treatment group and nine in the control group) were excluded from the analyses for different reasons. The incidence of PT/LBW in the treatment group was 2.14% (12/560) and in the control group, 6.71% (19/283) (odds ratio [OR] 3.26; 95% confidence interval [CI] 1.56 to 6.83; P = 0.0009). Multivariate logistic regression analysis showed that, after adjusting for several known risk factors for PT/LBW, women with gingivitis were at a higher risk of PT/LBW than women who received periodontal treatment (OR 2.76; 95%CI 1.29 to 5.88; P = 0.008). CONCLUSIONS: Periodontal treatment significantly reduced the PT/LBW rate in this population of women with pregnancy-associated gingivitis. Within the limitions of this study, we conclude that gingivitis appears to be an independent risk factor for PT/LBW for this population.

Subgingival microbiota of chilean patients with chronic periodontitis.

BACKGROUND: An association between race/ethnicity and the composition of the subgingival microbiota has been found in chronic periodontitis. A study was undertaken to determine the characteristics of the subgingival microbiota of chronic periodontitis in Chileans residing in Santiago. METHODS: Twenty-six subjects (mean age 45 +/- 7 years) with chronic periodontitis, mean probing depth (PD) 2.63 +/- 0.5 mm, mean attachment level (AL) 3.70 +/- 0.77 mm, and without a history of periodontal therapy were selected. Measurements of PD, AL, bleeding on probing, and plaque accumulation were recorded at six sites per tooth. Subgingival plaque samples were taken from the mesial aspect of every tooth and evaluated for the presence, levels, and proportions of 40 bacterial taxa using whole genomic DNA probes and checkerboard DNA-DNA hybridization. The microbial data of the Chileans were compared with data from 115 chronic periodontitis patients from Boston, Massachusetts. Since several clinical and demographic parameters differed between the two populations, significance of differences for each species was determined using analysis of covariance, adjusting for age, plaque level, mean PD, gender, and smoking status. RESULTS: Each of the individual test species was present in at least 25 of the 26 subjects, and 12 subjects (46.1%) harbored all 40 test species. With the exception of Prevotella intermedia, all test species colonized more than 75% of sites, and 25 species colonized > or = 90% of sites including the co-colonizing species of advanced periodontal lesions, termed the red complex, composed of the three species Porphyromonas gingivalis, Tannerella forsythensis (formerly Bacteroides forsythus), and Treponema denticola as well as Fusobacterium nucleatum subspecies, Campylobacter rectus, Peptostreptococcus micros, and Treponerma socranskii. Sixteen of the 40 species differed significantly between Chilean and U.S. subjects. Red, yellow, and other complexes were significantly higher in the Chileans, while the Actinomyces were higher in the U.S. subjects. CONCLUSIONS: The composition of the subgingival plaque differs among different subject populations. Thus, care should be taken when extrapolating the findings of one study to different ethnic groups.

Association of interleukin-1 polymorphisms with aggressive periodontitis.

BACKGROUND: Genetic polymorphisms for interleukin (IL)-1alpha and -1beta have been proposed as potential genetic markers for periodontal diseases. Since the prevalence of these polymorphisms could be race-related, and no data exist about the frequency of these polymorphisms in the Chilean population, the aim of the current study was to investigate the association of the interleukin-1 gene polymorphisms with aggressive periodontitis (AgP). METHODS: Thirty-six patients with AgP, 75 healthy controls, and 75 subjects of unknown periodontal status (reference population) were genotyped for the IL-1A -889 and IL-1B +3954 loci, by polymerase chain reaction (PCR) amplification followed by restriction enzyme digestion and gel electrophoresis. Data were analyzed using the chi-square test, calculating odds ratios (OR) and confidence intervals (CI). RESULTS: The prevalence of the positive composite IL-1 genotype was higher in patients (25%) than in healthy controls (12%), but the difference was not significant (P= 0.14). The IL-1B +3954 homozygous for allele 1 frequency was higher in controls than in patients suggesting a protective factor for AgP. The heterozygous for allele 2 of the IL- 1B showed a significant association with AgP (OR = 2.86, 95% CI 1.06 to 7.71, P= 0.030). No association was observed in localized AgP and generalized AgP between the extent of disease and the presence of the composite positive genotype. Because the number of smokers was too small in patients and in controls, no other analyses were performed. CONCLUSION: The results of the present study support a positive association between AgP and the presence of the IL-1B +3954 allele 2 polymorphism.

1.4 Research and the dental student.

There has been significant concern that the dental curriculum and system of clinical education, in particular, is not designed to take advantage of the explosion in knowledge in biomedical science and its application to the health of the public. Although there are some examples of innovations in dental education on a global scale that have the capacity to increase the assimilation of basic and clinical knowledge, most of the dental education models are mired in the traditional '2 + 2' approach to education. This can be seen in North America and the European '2 + 3' model or the stomatological '4 + 2' approach. In each of these systems, the basic and behavioural science courses continue to be perceived as hurdles over which students must leap in order to reach the clinical programmes where there is little opportunity to use basic science information to advance patient care and treatment. Examples of issues that are not well represented include: innovations in imaging; diagnosis; bio-materials; science-based approaches to clinical practice; novel approaches to therapeutics; interactions between the oral, dental and craniofacial complex and systemic health and disorders; the role of oral infections and systemic disease; the increasing appreciation of chronic diseases and disorders such as osteoporosis and diabetes that affect oral tissues; the promise of bioengineering, tissue engineering and biomimetics; the potential use of saliva as a diagnostic tool; the understanding of oral complications of cancer treatment; the treatments of HIV/AIDS diseases and hepatitis; the use of dental and dental hygiene staff on health-care teams to deal with issues such as birth defects, orofacial trauma, head and neck cancer, chronic pain management and so on. There seems to be an excessive emphasis on restorative dentistry and, to a lesser extent, on the more biological approaches to diagnosis, prevention and therapeutics. This continued lack of integration of basic and clinical sciences in the curriculum continues to foster a dental workforce that is highly technically competent to provide specific clinical services but poorly equipped to evaluate and implement new biological approaches to diagnosis, therapeutics and intervention. Unfortunately, after many attempts by organized dental symposia aimed at the integration of basic and clinical sciences, there has been little discernible curricular change. It appears that there is an opportunity through this global congress to identify the best practices in the various global curricula that could change this paradigm in dental education and lead us toward the education of a more scientifically orientated practitioner-one who can take advantage of innovations in new and emerging technologies in their application to patient care. It is the challenge of this section to try to ascertain the best method or methods by which dental education promotes research to the dental student and what research represents in terms of critical thinking and evidence-based approaches to dental education and clinical practice.

Periodontal therapy may reduce the risk of preterm low birth weight in women with periodontal disease: a randomized controlled trial.

BACKGROUND: Recent studies have suggested that periodontal disease is a risk factor for preterm low birth weight (PLBW). A randomized controlled trial was undertaken to help further evaluate the proposed association between periodontal disease and PLBW. METHODS: Four hundred pregnant women with periodontal disease, aged 18 to 35, were enrolled while receiving prenatal care in Santiago, Chile. Women were randomly assigned to either an experimental group (n = 200), which received periodontal treatment before 28 weeks of gestation or to a control group (n = 200) which received periodontal treatment after delivery. Previous and current pregnancies and known risk factors were obtained from patient medical records and interviews. The primary outcome assessed was the delivery at less than 37 weeks of gestation or an infant weighing less than 2,500 g. RESULTS: Of the 400 women enrolled, 49 were excluded from the analyses for different reasons. The incidence of PLBW in the treatment group was 1.84% (3/163) and in the control group was 10.11% (19/188), (odds ratio [OR] 5.49, 95% confidence interval [CI] 1.65 to 18.22, P= 0.001). Multivariate logistic regression analysis showed that periodontal disease was the strongest factor related to PLBW (OR 4.70, 95% CI 1.29 to 17.13). Other factors significantly associated with such deliveries were: previous PLBW (OR 3.98, 95% CI 1.11 to 14.21), less than 6 prenatal visits (OR 3.70, 95% Cl 1.46 to 9.38), and maternal low weight gain (OR 3.42, 95% CI 1.16 to 10.03). CONCLUSIONS: Periodontal disease appears to be an independent risk factor for PLBW. Periodontal therapy significantly reduces the rates of PLBW in this population of women with periodontal disease.