Is the misinterpretation of association and causation a never‐ending story?

Dear editor, we congratulate you for the editorial “Opportunistic Dentistry is Harming Our Credibility”.1 We applaud the initiative to revive the discussion on association and causation. Even though the topic has been exhaustively explored, there seems to be a need to extrapolate results in order to get a better audience to journals or newspapers, more patients into the clinics, justify grants, more respect or admiration from other colleagues, and so on. Indeed, opportunistic dentistry is harming our credibility among our peers and patients. Frequently, we are asked by colleagues and patients to elucidate whether causation is present in the almost 100 associations described so far between periodontitis and other health conditions.1 Spurious associations can be easily found when the respect for the existence of biological plausibility and temporal relationship between exposure and outcome are neglected. We recommend reading the case of dental flossing and obesity as an example.2 For the time being, we accept that “there is still no definitive evidence that treating oral disease has any clinically meaningful effect on the prevention, treatment, or outcomes of any systemic disease.”3 It is not surprising that individuals with systemic diseases may present several (un)healthy conditions at the same time, as a consequence of the exposure to and interaction of a multitude of shared risk factors. When a study detects a positive association between periodontitis and a systemic condition, it only shows that this group of people, in addition to periodontitis, also has a higher chance of suffering from the systemic condition under investigation. It is entirely different from saying that the development of periodontitis caused or contributed to the onset and progression of a specific systemic disease. Causal inference studies are scarce in the dental field and, even when found, suffer from relevant methodological limitations in data quality (particularly insufficient sample size and inaccurate analytical approach), which preclude the drawing of causal relationships.No Full Tex

Quantification of Endotoxins in Infected Root Canals and Acute Apical Abscess Exudates: Monitoring the Effectiveness of Root Canal Procedures in the Reduction of Endotoxins

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Introduction: This clinical study was conducted to measure the endotoxin levels in infected root canals (RCs) and exudates related to acute apical abscesses (AAAs). In addition, the effectiveness of RC procedures in reducing the endotoxin levels in RCs was monitored. Methods: Paired samples of infected RCs and exudates from AAAs were collected from 10 subjects by using paper points. RCs samples were collected before (RCS1) and after chemomechanical preparation (CMP) (RCS2), after 17% EDTA (RCS3), and after 30 days of intracanal medication (Ca[OH](2) + chlorhexidine) (RCS4). A turbidimetric kinetic limulus amebocyte lysate assay was used for the measurement of endotoxins. Results: Endotoxins were detected in 100% of the baseline samples of AAAs and RCs (RCS1) with median values of 175 EU/mL and 41.5 EU/mL, respectively (P < .05). After CMP (RCS2), endotoxins were reduced to a median value of 0.54 EU/mL (P < .05). Subsequent irrigation with EDTA (RCS3) failed to present a significant effectiveness in reducing the endotoxin levels (median = 0.37 EU/mL) (P = .07). However, intracanal medication for 30 days (RCS4) reduced endotoxins to median values of 0.03 EU/mL (P < .01). Conclusions: The present study revealed a strong association between the high levels of endotoxins found in AAAs and RCs collected from the same tooth. Moreover, the effectiveness of CMP in reducing the endotoxin levels from RCs in acute endodontic infection was improved by the use of RC medication.402177181Brazilian agencies: PAPESP [10/17877-4, 10/19136-1, 11/09047-4]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Brazilian agencies: PAPESP [10/17877-4, 10/19136-1, 11/09047-4]CNPq [302575/2009-0, 150557/2011-6

Antigenic Activity of Bacterial Endodontic Contents from Primary Root Canal Infection with Periapical Lesions against Macrophage in the Release of Interleukin-1 beta and Tumor Necrosis Factor alpha

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Introduction: Periradicular tissue chronic stimulation by endotoxin may cause apical periodontitis. This study investigated the microbial profile and the levels of endotoxin found in primary root canal infection with apical periodontitis, determined their antigenicity against macrophages through the levels of interleukin (IL)-1 beta and tumor necrosis factor alpha (TNF-alpha), and evaluated their relationship with clinical and radiographic findings. Methods: Samples were taken from 21 root canals with primary endodontic infection and apical periodontitis with paper points. PCR technique (16S rDNA) was used for the detection of the target bacteria. Limulus Amebocyte Lysate (LAL) was used to measure endotoxin. The amounts of IL-1 beta/TNF-alpha in macrophages supernatants were measured by enzyme-linked immunosorbent assay - Duoset-kit (ELISA). Results: Prevotella nigrescens (13/21), Porphyromonas endodontalis (6/21), and Treponema socranskii (6/21) were the most frequently detected gram-negative bacterial species. The presence of the sinus tract (2/21) was related to the detection of Filifactor alocis (p = 2 mm was related to the detection of Treponema denticola. A correlation was found between the number of gram-negative bacteria and the levels of IL-1 beta/TNF-alpha (p < 0.05). Increased levels of endotoxin were followed by TNF-alpha release (p < 0.05). Higher levels of IL-1 beta (p < 0.05) and endotoxin contents were related to the larger size of the radiolucent area. Conclusion: The antigenicity of the endodontic contents is not only related to the amount of endotoxin found in the root canal but also to the number of different species of gram-negative bacteria involved in the infection. Moreover, a larger size (2 mm) of the radiolucent area was related to IL-1 beta and endotoxin. (J Endod 2010;36:1467-1474)36914671474Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [07/58518-4, 08/58299-3, 08/ 57954-8, 08/57551-0]CNPq [3470820/2006-3, 471631/2008-6, 302575/2009-0

Dietary vitamin D and calcium and periodontitis: A population-based study

Aim: This study aimed to explore the relationship between dietary vitamin D and calcium intake and periodontitis among adults and whether it differs from males to females. Methods: Cross-sectional analysis of a population-based cohort study with adults aged 20 to 60 from Southern Brazil. Intake of vitamin D and calcium were gathered in 2012 using two 24h-dietary recalls. Clinical examination assessed the clinical attachment level and bleeding on probing. Confounders included sex, age, family income, smoking, and obesity. The controlled direct effect of vitamin D and calcium on periodontitis was examined using marginal structural modeling. Analyses were also stratified by sex. Results: Of the 1,066 investigated adults (mean age 35 ± 11.7 years; 49% females), 12.3% (95%CI 10.2;14.7) had periodontitis. Calcium intake had a direct protective effect on periodontitis (risk ratio (RR) 0.61; 95%CI 0.45;0.83), whereas no association between vitamin D and periodontitis was observed (RR 1.13; 95%CI 0.82;1.56). Stratified analyses revealed a null association between both vitamin D and calcium intake and periodontitis among men, but a protective association between calcium and intake and periodontitis among women (RR 0.56; 95%CI 0.38;0.79), while vitamin D remained without any association (RR 1.07; 95%CI 0.72;1.61). Conclusion: Our findings suggest a protective association between dietary calcium intake and periodontitis among women.Full Tex

Cumulative smoking exposure and cessation associated with the recurrence of periodontitis in periodontal maintenance therapy: A 6‐year follow‐up

Background: This study followed individuals in periodontal maintenance therapy (PMT) over 6 years and longitudinally evaluated the effects of cumulative smoking exposure and duration of smoking cessation on the recurrence of periodontitis. Methods: From a 6-year follow-up cohort study with 212 individuals in PMT, 142 patients who attended at least one PMT visit within 12 months were determined to be elegible. According to smoking habits they were categorized into three groups: non-smokers (NS; n = 95), former smokers (FS; n = 22), and current smokers (CS; n = 25). Complete periodontal examination and smoking habits were evaluated at two instances: T1 (first time, after active periodontal therapy) and T2 (second time, 6 years). Associations between the recurrence of periodontitis (RP; probing depth ≥4 mm and clinical attachment loss ≥3 mm, together with the presence of bleeding on probing and/or suppuration), smoking status, and potential risk variables were analyzed by univariate and multivariate analysis, when appropriate. Results: The RP in NS, FS, and CS groups was 44.2%, 68.2%, and 80.0%, respectively. After adjusting for confounders, odds ratios (95% confidence interval) for the RP in T2 was 2.80 (2.11 to 5.14) for FS and 5.97 (3.58 to 9.88) for CS. There was a significant dose-response relationship between pack-years of smoking and the RP, as well as a significant decrease in the risk for the RP as the years of smoking cessation increased. Conclusion: During 6 years of PMT, cumulative smoking exposure and shorter time since smoking cessation were significantly associated with the RP

Signaling pathways associated with the expression of inflammatory mediators activated during the course of two models of experimental periodontitis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Aims: Evaluate the signaling pathways associated with inflammatory mediators activated in two models of experimental periodontitis. Main methods: Two models were used: lipopolysaccharide (LPS) injections and ligature placement. Wistar rats were used and 30 mu g LIPS from Escherichia coli was injected twice a week into the palatal aspect of the upper molars. Ligatures were placed around lower first molars. A control group received injections of PBS on the palatal gingivae whereas no ligatures were placed on the lower molars. Samples were collected 5,15 and 30 days and processed for analysis by Western blotting and stereometry. Key findings: The ligature model was associated with rapid and transient activation of extracellular-regulated kinases (ERK) and p38 mitogen-activated protein kinase (MAPK) as well as of nuclear factor kappa B (NF-kappa B). Activation of these signaling pathways on the LPS model was delayed but sustained throughout the 30-day experimental period. Inflammatory changes induced by both models were similar; however there was a significant reduction on inflammation degree on the ligature model, which paralleled the decrease observed on the activation of the signaling pathways. Activation of signal transducer and activator of transcription (SEAT)-3 by phosphorylation of Tyrosine residues and of SPAT-5 was observed only on the ligature model. Significance: Regulation of gene expression results from the activation of signaling pathways initiated by receptor-ligand binding of external antigens and also of cytokines produced by the host immune system. Understanding the signaling pathways relevant fora given condition may provide information useful for novel therapeutic approaches. (C) 2009 Elsevier Inc. All rights reserved.8421-22745754Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2005/04428-9, 2006/07283-4

Blood cell attachment to root surfaces treated with EDTA gel Adesão de células sangüíneas a superfícies radiculares tratadas com gel de EDTA

Root debridement generates a smear layer which contains microorganisms and toxins that could interfere in periodontal healing. For this reason, different substances have been used to remove it and to expose collagen fibers at the tooth surface. Blood element adhesion to demineralized roots and clot stabilization by collagen fibers are extremely important for the success of periodontal surgery. The aim of this study was to evaluate the different patterns of blood element adsorption and adhesion to root surfaces only irrigated with distilled water and after application of a manipulated or an industrialized EDTA gel. Thirty samples were planed, equally divided into three groups and treated with distilled water (control), a manipulated EDTA gel or an industrialized one. Immediately after, samples were exposed to fresh blood and prepared for scanning electron microscopy. Untreated planed dentin presented the best results with blood cells entrapped in a thick web of fibrin. In the manipulated EDTA group, the web of fibrin was thick with sparse blood elements. The worst result was seen with the industrialized EDTA group, in which no blood elements could be seen. Statistical difference was obtained between control and industrialized EDTA groups. Surfaces only irrigated presented the most organized fibrin network and cell entrapment.<br>A raspagem gera "smear layer", a qual contém microrganismos e toxinas que podem interferir no reparo periodontal. Por esse motivo, diferentes substâncias têm sido empregadas para remover esta camada e expor fibras colágenas da superfície dental. A adesão de elementos sangüíneos a superfícies radiculares desmineralizadas e a estabilização do colágeno pelas fibras colágenas são de extrema importância no sucesso da cirurgia periodontal. O objetivo deste estudo foi avaliar os diferentes padrões de adsorção e adesão de elementos sangüíneos a superfícies radiculares apenas irrigadas com água destilada e após aplicação de um gel de EDTA manipulado ou um industrializado. Trinta amostras foram raspadas, eqüitativamente divididas em 3 grupos e tratadas com água destilada (controle), um gel de EDTA manipulado ou um industrializado. Imediatamente foram expostas a sangue fresco e preparadas para microscopia eletrônica de varredura. As superfícies dentinárias apenas raspadas apresentaram os melhores resultados, com moderada quantidade de células sangüíneas entremeadas em uma fina rede de fibrina. No grupo de EDTA manipulado, a rede de fibrina foi pouco visível com escassas células. Os piores resultados foram observados com o EDTA industrializado, caracterizados pela ausência de elementos sangüíneos. Estatisticamente houve diferença apenas entre os grupos controle e EDTA industrializado. As superfícies apenas irrigadas apresentaram rede de fibrina mais bem organizada com células entremeadas

Comparação in vitro da eficácia de diferentes formulações do gel de EDTA 24% no condicionamento da superfície radicular

INTRODUCTION: The main goal of root biomodification is to modify the root surface in order to improve the repair of periodontal tissues destroyed by periodontal disease. OBJECTIVE: To evaluate the conditioning efficacy of 24% EDTA gel of different trademarks, considering the variables time and application method, by scanning electron microscopy. MATERIAL AND METHOD: 225 samples were randomly assigned to five groups: sterile saline solution (control); 24% EDTA (Santa Paula Pharmacy); 24% EDTA-T (Santa Paula Pharmacy); 24% EDTA (PrefGel - Straumann); 24% EDTA (Biodinâmica). For each experimental group the gels were applied for 1, 2 or 3 minutes by topical application; vigorous or smooth friction. The Kruskal-Wallis and Dunn tests (p < 0,05) were used and individually applied to the variables commercial brand, time and type of application. RESULT: The statistical analysis showed that 24% EDTA Biodinâmica gel promoted less smear layer removal compared to the other groups. No significant differences could be detected among the different times of application. The smooth friction resulted in lower amount of residual smear layer. CONCLUSION: All 24% EDTA gels tested were able to remove smear layer and to expose dentinal tubules irrespective of application time; however, the application method by smooth friction was more effective than the other ones. The comparative analysis demonstrated that the Biodinâmica gel was the least effective product, promoting less smear layer removal and exposure of collagen fibers than the other EDTA gels.INTRODUÇÃO: A biomodificação radicular visa a alterar a superfície radicular para auxiliar no reparo das estruturas periodontais de suporte destruídas pela doença periodontal. OBJETIVO: Avaliar por meio de microscopia eletrônica de varredura a eficácia do condicionamento químico com gel de EDTA 24% na remoção de smear layer e na exposição de fibras colágenas, verificando-se diferentes marcas comerciais, modos e tempos de aplicação. MATERIAL E MÉTODO: Um total de 225 amostras foram obtidas e distribuídas aleatoriamente em cinco grupos: soro fisiológico (controle); EDTA 24% (Farmácia Santa Paula); EDTA-T 24% (Farmácia Santa Paula); EDTA 24% (PrefGel; Straumann); EDTA 24% (Biodinâmica). As amostras de cada grupo foram redistribuídas aleatoriamente em subgrupos (n = 5) e condicionadas com os diferentes géis de EDTA nos tempos de 1, 2 e 3 minutos, e nos modos de aplicação tópica, fricção vigorosa e fricção suave. Os testes de Kruskal-Wallis e Dunn (p < 0,05) foram utilizados e aplicados separadamente para os fatores: marca comercial, tempo e modo de aplicação. RESULTADO: A análise estatística revelou que o gel de EDTA 24% da Biodinâmica promoveu a menor remoção de smear layer. Não foram detectadas diferenças estatísticas para os tempos de aplicação. O modo de aplicação fricção suave resultou em menor quantidade de smear layer residual. CONCLUSÃO: Todos os géis de EDTA 24% utilizados foram eficazes na remoção de smear layer e na exposição de fibras colágenas, independentemente do tempo de aplicação; no entanto, o modo de fricção suave foi mais efetivo. Na análise comparativa entre os produtos, o EDTA da Biodinâmica foi menos efetivo, já que promoveu menor remoção de smear layer e exposição de fibras colágenas.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Univ Estadual Paulista Faculdade de Odontologia de AraraquaraUniv Estadual Paulista Faculdade de Odontologia de Araraquara Departamento de Odontologia RestauradoraUniv Estadual Paulista Faculdade de Odontologia de Araraquara Departamento de Diagnóstico e CirurgiaUniv Estadual Paulista Faculdade de Odontologia de AraraquaraUniv Estadual Paulista Faculdade de Odontologia de Araraquara Departamento de Odontologia RestauradoraUniv Estadual Paulista Faculdade de Odontologia de Araraquara Departamento de Diagnóstico e Cirurgi