Identification and classification of pulp calcifications in posterior teeth according to dental condition using digital panoramic radiography and cone beam computed tomography.

OBJECTIVE: To compare digital panoramic radiography (DPR) and cone beam computed tomography (CBCT) in the detection and classification of pulp calcifications in posterior teeth in relation to tooth condition and its location. METHODS: 250 patients with simultaneous DPR and CBCT scans were selected from a dental image bank. For each posterior tooth, its condition was registered (healthy, restored, or decayed). The presence of calcifications was assessed and classified according to location (coronal or radicular) and type (total obliteration, partial obliteration, narrowing, and no calcification). Chi-square and McNemar tests were used to compare DPR and CBCT results, with a significance level of 5%. DPR diagnostic values were calculated using CBCT as reference. RESULTS: Decayed and restored teeth showed a significantly (p < 0.001) higher prevalence of pulp calcifications than healthy teeth in both imaging exams. There was a significant discrepancy between the imaging modalities in the identification of calcifications (p < 0.001), especially for radicular calcifications of maxillary teeth (DPR = 55.2%; CBCT = 30.9%). In the case of coronal calcifications, there was a greater discrepancy between CBCT and DPR in the mandibular teeth (10.7%) than in the maxillary teeth (7.7%). Overall, DPR presents higher sensitivity (0.855) than specificity (0.483) for pulp calcifications detection. CONCLUSION: DPR considerably overestimates pulp calcifications in posterior teeth, as compared to CBCT. A higher prevalence of pulp calcifications is related to decayed and restored teeth.

Impact of low-fusion gutta-percha cones used in variations of the continuous wave condensation technique with filling sealers based on bioceramic compounds on the quality of root canal filling.

To evaluate the impact on the quality of filling with of low-fusion and conventional gutta-percha cones. Thirty-six maxillary canines were prepared and divided into three groups: I-conventional cone with Downpack at 200 °C at 4 mm from the WL; II-low-fusion cone with Downpack at 100 °C up to 4 mm from the WL; III-low-fusion cone with Downpack at 100 °C up to 7 mm from the WL. Temperature variations were measured in thirds on the external surface of the root. The bond strength was evaluated using the push-out test. The adhesive interface was analyzed by scanning electron microscopy. The bond strength and the temperature variation data were analyzed using analysis of variance and the failure type using the chi-square test. The low-fusion cone group with 7 mm Downpack showed higher bond strength (4.2 ± 2.7) compared with conventional cones (2.8 ± 1.6) and low-fusion cones with 4 mm Downpack (2.9 ± 1.6) (p < 0.05), with occurrence of a higher number of adhesive failures to the filling material and mixed failures. Relative to temperature variation, there was less temperature change in the apical third, in the low-fusion cone with Downpack 7 mm (1.0 ± 1.0) (p < 0.05). The use of low-fusion cones allowed the continuous wave condensation technique to be performed at a lower depth of Downpack at 100 °C at 7 mm, with less heating in the apical third, without compromising the quality of filling. Using gutta-percha cones with low fusion, which permits a lower condensation temperature and reduced Downpack depth, maintains the quality of filling, in order to minimize possible damage to the periapical tissues.

Impact of access cavities on root canal preparation, restorative protocol quality, and fracture resistance of teeth.

The survival of endodontically treated teeth depends on the remaining tooth structure. The aim of this study was to evaluate the impact of different access cavities on root canal preparation, restorative protocol, and fracture resistance of endodontically treated teeth. Fifty-six mandibular molars were divided into control (n=8) and experimental (n=16) groups according to access cavity: Traditional, Conservative, and Truss; and redistributed (n=8) according to instrumentation protocols: Reciproc Blue and R-motion. After, teeth were scanned in micro-CT and then filled and redistributed according to composite resin restoration (n=8): Filtek One BulkFill and Filtek Z350. A new micro-CT scan was performed to analyze the restorative material. Then, samples were submitted to fracture resistance testing and the failure pattern was determined. Data were analyzed using paired T-test, ANOVA, Tukey, and chi-square tests (α=0.05). In Truss, R-Motion promoted less transportation in different thirds of root canals. Higher percentages of voids (5.05%) and filling material (11.7%) were observed in Truss. Fracture resistance values were higher for the control group, followed by Truss, Conservative, and Traditional. The predominant failure pattern was type-II. In Truss, reciprocating instruments with smaller taper showed less canal transportation. Also, Truss provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material. Thus, in Truss, reciprocating files with smaller taper showed less canal transportation, and these cavities provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material.

Systemic inhibition of 5-lipoxygenase by MK-886 exacerbates apical periodontitis bone loss in a mouse model.

BACKGROUND: To investigate if 5-LO selective inhibitor (MK-886) could be used for systemic treatment of experimentally induced apical periodontitis in a mouse model. METHODS: Twenty-four C57BL/6 mice were used. After coronal opening, a solution containing Escherichia coli LPS (1.0 µg/µL) was inoculated into the root canals of the lower and upper right first molars (n = 72 teeth). After 30 days apical periodontitis was established, and the animals were treated with MK-886 (5 mg/kg), a 5-LO inhibitor, for 7 and 14 days. The tissues were removed for histopathological and histometric analyses, evaluation of osteoclast number and gene expression for receptor activator of nuclear factor kappa-B (Tnfrsf11a), receptor activator of nuclear factor kappa-B ligand (Tnfsf11), osteoprotegerin (Tnfrsf11b), tartrate-resistant acid phosphatase (Acp5), matrix metalloproteinase-9 (Mmp9), cathepsin K (Ctsk) and calcitonin receptor (Calcr). Statistical data analysis was performed using Kruskal Wallis followed by Dunn's tests (α = 0.05). RESULTS: Administration of MK-886 for 7 days exerted no effect on apical periodontitis progression compared to LPS inoculation without treatment (p = 0.3549), while treatment for 14 days exacerbated bone loss (p < 0.0001). Administration of MK-886 enhanced osteoclastogenesis signaling and osteoclast formation within 7 days (p = 0.0005), but exerted no effect at 14 days (p > 0.9999). After 7 days of treatment, MK-886 induced mRNA expression for Acp5 (p = 0.0001), Calcr (p = 0.0003), Mmp9 (p = 0.0005) and Ctsk (p = 0.0008), however no effect in those gene expression was observed after 14 days (p > 0.05). CONCLUSION: Systemic treatment with MK-886 exacerbated LPS-induced apical periodontitis in a mouse model.

Evaluation of rotary instruments with whipping motion in the biomechanical preparation of large root canals of young permanent teeth.

Shaping ability evaluation of taper ./01 instruments in large root canals, by microcomputed tomography (micro-CT) and scanning electron microscopy (SEM). Maxillary central incisors with large diameter root canals were divided into two groups (n = 10): XP-Endo Shaper (FKG-Dentaire, Switzerland) and manual instrumentation (FKG-Dentaire). Two- and three-dimensional parameters from cervical to apical root thirds were evaluated by micro-CT. Apical stop was evaluated by SEM images. Data were analysed by ANOVA and Tukey tests (α = 5%). XP-Endo Shaper allowed a regular biomechanical preparation with less dentinal wear compared with manual instrumentation, which showed excessive wear of the thin root canal walls (p < 0.05). Roundness and SMI showed similarity between both protocols (p > 0.05). XP-Endo Shaper SEM showed a regular and well-defined shape of the apical foramen suggesting the formation of the apical stop. Reduced diameter and taper instruments promoted a conservative wear and a well-defined apical stop formation in large root canals.

Genetic polymorphism in the tumour necrosis factor alpha gene (G-308A) is associated with persistent apical periodontitis in Brazilians.

AIM: To investigate if there was an association between genetic polymorphisms in tumour necrosis factor (TNF)-⍺ and its receptors TNFRSF1A and TNFRSF1B with persistent apical periodontitis (PAP) in Brazilian subjects. METHODOLOGY: Patients who had pulpal necrosis and apical periodontitis at the time of treatment, with at least 1-year of follow-up after non-surgical root canal treatment were recalled. Three hundred and seventy eight subjects were included, 150 subjects with signs/symptoms of PAP and 228 subjects with root canal-treated teeth exhibiting healthy perirradicular tissues (healed). Genomic DNA was extracted from saliva and used for TNF-⍺ (rs1800629), TNFRSF1A (rs1800693) and TNFRSF1B (rs1061622) genotyping by real-time PCR. Genotypes and alleles frequencies were evaluated by c2 or Fisher's exact tests and odds ratios were implemented (α = 5%). RESULTS: The genetic polymorphism in TNF-α (rs1800629) was associated as a protective factor for the development of PAP (p < .05), once subjects who presented at least one allele A (AA+AG X GG), had a higher chance to lesion repair (p < .05). The polymorphisms rs1800693 and rs1061622 in TNF receptors (TNFRSF1A and TNFRSF1B, respectively) were not associated with the development of PAP (p > .05). CONCLUSIONS: The observed results demonstrate that polymorphism in TNF-α but not in its receptors is associated with PAP.

Impact of access cavities on root canal preparation, restorative protocol quality, and fracture resistance of teeth

Abstract The survival of endodontically treated teeth depends on the remaining tooth structure. The aim of this study was to evaluate the impact of different access cavities on root canal preparation, restorative protocol, and fracture resistance of endodontically treated teeth. Fifty-six mandibular molars were divided into control (n=8) and experimental (n=16) groups according to access cavity: Traditional, Conservative, and Truss; and redistributed (n=8) according to instrumentation protocols: Reciproc Blue and R-motion. After, teeth were scanned in micro-CT and then filled and redistributed according to composite resin restoration (n=8): Filtek One BulkFill and Filtek Z350. A new micro-CT scan was performed to analyze the restorative material. Then, samples were submitted to fracture resistance testing and the failure pattern was determined. Data were analyzed using paired T-test, ANOVA, Tukey, and chi-square tests (α=0.05). In Truss, R-Motion promoted less transportation in different thirds of root canals. Higher percentages of voids (5.05%) and filling material (11.7%) were observed in Truss. Fracture resistance values were higher for the control group, followed by Truss, Conservative, and Traditional. The predominant failure pattern was type-II. In Truss, reciprocating instruments with smaller taper showed less canal transportation. Also, Truss provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material. Thus, in Truss, reciprocating files with smaller taper showed less canal transportation, and these cavities provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material.

Heat-treated NiTi instruments and final irrigation protocols for biomechanical preparation of flattened canals.

This study evaluate shaping ability of heat-treated NiTi-alloy instruments associated with different final irrigation protocols in flattened root canals. Thirty human mandibular incisors with flattened root canals were divided into 5 groups (n = 10): (XP) Original Protocol XP-endo Shaper; (XP-WT) Original Protocol XP-endo Shaper with working time variation; (XP-K) XP-endo Shaper with kinematics variation; (XP-WTK) XP-endo Shaper with kinematics and working time variations; (Hyflex) Hyflex CM. For the variation in working time protocols the same sample of the XP-endo Shaper groups with and without kinematic variation were used. To evaluate final irrigation protocols, groups 1, 3 and 5 were submitted to 3 protocols: (NI) No irrigation (n = 2); (CI) conventional irrigation (n = 4), and (EndoVac) irrigation (n = 4). The samples were scanned by microcomputed tomography and prepared for scanning electron microscopy evaluation. Quantitative data were evaluated using the parametric ANOVA test, with statistical significance level set at 5%, and qualitative data obtained were compared to establish the agreement between examiners through the Kappa test. It was observed that in the analysis of XP-endo Shaper protocols, the additional working time did not cause difference in any of parameters evaluated (p > 0.05) in relation to time recommended by manufacturer. Compared to Hyflex, XP-K showed highest mean volume increase (p < 0.05) and lowest percentage of untouched walls (p < 0.05). In the qualitative evaluation, final irrigation protocol with EndoVac provided the best cleaning results when associated with XP-K and with Hyflex. Thus, supplementary techniques are effective tools to enhance cleaning and to promote higher touch of walls during root canal preparation.

Genetic, Cellular and Molecular Aspects involved in Apical Periodontitis.

The development, establishment and repair of apical periodontitis (AP) is dependent of several factors, which include host susceptibility, microbial infection, immune response, quality of root canal treatment and organism's ability to repair. The understanding of genetic contributions to the risk of developing AP and presenting persistent AP has been extensively explored in modern Endodontics. Thus, this article aims to provide a review of the literature regarding the biochemical mediators involved in immune response signaling, osteoclastogenesis and bone neoformation, as the genetic components involved in the development and repair of AP. A narrative review of the literature was performed through a PUBMED/MEDLINE search and a hand search of the major AP textbooks. The knowledge regarding the cells, receptors and molecules involved in the host's immune-inflammatory response during the progression of AP added to the knowledge of bone biology allows the identification of factors inherent to the host that can interfere both in the progression and in the repair of these lesions. The main outcomes of studies evaluated in the review that investigated the correlation between genetic polymorphisms and AP in the last five years, demonstrate that genetic factors of the individual are involved in the success of root canal treatment. The discussion of this review gives subsides that may help to glimpse the development of new therapies based on the identification of therapeutic targets and the development of materials and techniques aimed at acting at the molecular level for clinical, radiographic and histological success of root canal treatment.

Genetic, Cellular and Molecular Aspects involved in Apical Periodontitis

Abstract The development, establishment and repair of apical periodontitis (AP) is dependent of several factors, which include host susceptibility, microbial infection, immune response, quality of root canal treatment and organism's ability to repair. The understanding of genetic contributions to the risk of developing AP and presenting persistent AP has been extensively explored in modern Endodontics. Thus, this article aims to provide a review of the literature regarding the biochemical mediators involved in immune response signaling, osteoclastogenesis and bone neoformation, as the genetic components involved in the development and repair of AP. A narrative review of the literature was performed through a PUBMED/MEDLINE search and a hand search of the major AP textbooks. The knowledge regarding the cells, receptors and molecules involved in the host's immune-inflammatory response during the progression of AP added to the knowledge of bone biology allows the identification of factors inherent to the host that can interfere both in the progression and in the repair of these lesions. The main outcomes of studies evaluated in the review that investigated the correlation between genetic polymorphisms and AP in the last five years, demonstrate that genetic factors of the individual are involved in the success of root canal treatment. The discussion of this review gives subsides that may help to glimpse the development of new therapies based on the identification of therapeutic targets and the development of materials and techniques aimed at acting at the molecular level for clinical, radiographic and histological success of root canal treatment.

Resumo O desenvolvimento, estabelecimento e reparo da periodontite apical (PA) depende de vários fatores, que incluem a susceptibilidade do hospedeiro, infecção microbiana, resposta imune, bem como a qualidade do tratamento do canal radicular e a capacidade de reparo do organismo. A compreensão das contribuições genéticas para o risco de desenvolver a PA e apresentar PA persistente tem sido extensivamente explorada na Endodontia moderna. Assim, este manuscrito pretende fornecer uma revisão da literatura em relação aos mediadores bioquímicos envolvidos na sinalização da resposta imune, osteoclastogênese e neoformação óssea, bem como os componentes genéticos envolvidos no desenvolvimento e reparo da PA. Uma revisão narrativa da literatura foi realizada através de uma pesquisa nas bases PUBMED/MEDLINE e uma pesquisa manual nos principais livros sobre a PA. O conhecimento sobre as células, receptores e moléculas envolvidas na resposta imuno-inflamatória do hospedeiro durante a progressão da PA somado ao conhecimento da biologia óssea, especialmente o papel dos osteoblastos, osteócitos e osteoclastos no turnover ósseo, permite a identificação de fatores inerentes ao hospedeiro que podem interferir tanto na progressão como no reparo destas lesões. Os principais resultados dos estudos avaliados na revisão que investigaram a correlação entre polimorfismos genéticos e PA, nos últimos cinco anos, demonstram que os fatores genéticos do indivíduo estão envolvidos no sucesso do tratamento do canal radicular. A discussão desta revisão fornece subsídios que podem ajudar a vislumbrar o desenvolvimento de novas terapias baseadas na identificação de alvos terapêuticos e no desenvolvimento de materiais e técnicas destinadas a atuar a nível molecular para o sucesso clínico, radiográfico e histológico do tratamento endodôntico.

Impact of several NiTi-thermally treated instrumentation systems on biomechanical preparation of curved root canals in extracted mandibular molars.

AIM: To evaluate the shaping ability of several heat-treated nickel-titanium systems used to prepare root canals with moderate and severe curvature, in extracted mandibular molars, by micro-computed tomography, considering their variation in kinematics and design. METHODOLOGY: Curved-mesial roots of mandibular molars were randomly selected and assigned into 4 balanced experimental groups (n = 10), established by determining homogeneous 3D parameters of volume and surface area: R-Motion (RM) size 30, 0.04 taper (RM; FKG Dentaire), Reciproc Blue (RCB) size 25, 0.08 taper (RCB; VDW GmbH), HyFlex CM (HFX) size 30, 0.04 taper (HFX; Coltène Whaledent) and XP-endo Shaper size (XPS) 30, 0.01 taper (XPS; FKG Dentaire). The volume of irrigation was established at 10 ml of 2.5% NaOCl. Throughout the entire root canal preparation procedures, the samples were fixed in a vice submerged in a container with water monitored at 37°C. Dimensional cross-sectional measures of area, perimeter, roundness, major/minor diameters and 3-dimensional (volume, surface area, structure model index - SMI) parameters as well as the smallest dentine thickness along the cervical and middle root thirds were evaluated by micro-CT. Data were analysed using analysis of variance and post hoc Tukey tests (α = 5%). RESULTS: Reciproc Blue and XPS had significantly greater mean increases in cross-sectional area measurements, only in the middle third, when compared with RM and HFX (p < .05). RM, RCB and XPS had a similar increase in measurements of length and width of perimeter (p > .05), and HFX had significantly lower mean increases in perimeter values only when compared with XPS (p < .05). RCB and XPS had significantly greater mean increases in volume when compared with RM and HFX (p < .05). RM had a significantly lower difference in SMI after preparation, compared with RCB, HFX and XPS (p < .05). The smallest dentine thickness was observed after the use of RCB (p < .05), in the danger and safety zones. CONCLUSIONS: XP-endo Shaper and RM had a shaping ability similar to that of instruments with larger tapers, achieved with less dentine removal in danger and safe zones in curved-mesial canals of extracted molar teeth treated on a laboratory benchtop.

Impact of Endodontic Kinematics on Stress Distribution During Root Canal Treatment: Analysis of Photoelastic Stress.

INTRODUCTION: Structural defects created by endodontic treatment are the most common cause of major dental failures. This study analyzed levels of stress produced by endodontic instruments during the root canal treatment by photoelastic analysis of stress. METHODS: Twenty-four human premolars were randomly divided into 4 groups (n = 6) according to instrumentation protocol: ProTaper Next (GPT), One Shape (GOS), Wave One Gold (GWO), and TF Adaptive (GTF). The evaluation of the photoelastic model was performed at 4 dental zones: dental-crown region, cervical third of root, middle third of root, and apical third of root. Silicone molds were prepared (2 × 15 mm), and pinjets were used inside the root canals to fixate teeth. Photoelastic resin (2:1 ratio) was poured into the silicone molds to form photoelastic models. A transmission polariscope was used to analyze the positions of interest and recorded with a digital camera. Tardy's method was used to quantify the fringe order (n) and calculate the maximum stress value (τ) at each selected point. Data were analyzed with two-way analysis of variance, Tukey test (P < .05), fringe descriptive analysis. RESULTS: All groups showed a significant increase in the level of stress created during biomechanical preparation of the root canals. In the quantitative analysis, there was no statistically significant difference among the groups (P > .05). In the qualitative analysis, GPT and GTF instruments achieved greater levels of stresses compared with GWO and GOS instruments. At the beginning of instrumentation, stresses were concentrated at the coronary level and the end of instrumentation at the middle and apical root level. CONCLUSIONS: All endodontic systems resulted in accumulation of stress along the dental structure. Stress was found in different concentrations along the tooth and at different levels.

Heat-treated NiTi instruments and final irrigation protocols for biomechanical preparation of flattened canals

Abstract This study evaluate shaping ability of heat-treated NiTi-alloy instruments associated with different final irrigation protocols in flattened root canals. Thirty human mandibular incisors with flattened root canals were divided into 5 groups (n = 10): (XP) Original Protocol XP-endo Shaper; (XP-WT) Original Protocol XP-endo Shaper with working time variation; (XP-K) XP-endo Shaper with kinematics variation; (XP-WTK) XP-endo Shaper with kinematics and working time variations; (Hyflex) Hyflex CM. For the variation in working time protocols the same sample of the XP-endo Shaper groups with and without kinematic variation were used. To evaluate final irrigation protocols, groups 1, 3 and 5 were submitted to 3 protocols: (NI) No irrigation (n = 2); (CI) conventional irrigation (n = 4), and (EndoVac) irrigation (n = 4). The samples were scanned by microcomputed tomography and prepared for scanning electron microscopy evaluation. Quantitative data were evaluated using the parametric ANOVA test, with statistical significance level set at 5%, and qualitative data obtained were compared to establish the agreement between examiners through the Kappa test. It was observed that in the analysis of XP-endo Shaper protocols, the additional working time did not cause difference in any of parameters evaluated (p > 0.05) in relation to time recommended by manufacturer. Compared to Hyflex, XP-K showed highest mean volume increase (p < 0.05) and lowest percentage of untouched walls (p < 0.05). In the qualitative evaluation, final irrigation protocol with EndoVac provided the best cleaning results when associated with XP-K and with Hyflex. Thus, supplementary techniques are effective tools to enhance cleaning and to promote higher touch of walls during root canal preparation.

Root canal contamination or exposure to lipopolysaccharide differentially modulate prostaglandin E 2 and leukotriene B 4 signaling in apical periodontitis.

Purpose To evaluate the kinetics of apical periodontitis development in vivo , induced either by contamination of the root canals by microorganisms from the oral cavity or by inoculation of bacterial lipopolysaccharide (LPS) and the regulation of major enzymes and receptors involved in the arachidonic acid metabolism. Methodology Apical periodontitis was induced in C57BL6 mice (n=96), by root canal exposure to oral cavity (n=48 teeth) or inoculation of LPS (10 µL of a suspension of 0.1 µg/µL) from E. coli into the root canals (n= 48 teeth). Healthy teeth were used as control (n=48 teeth). After 7, 14, 21 and 28 days the animals were euthanized and tissues removed for histopathological and qRT-PCR analyses. Histological analysis data were analyzed using two-way ANOVA followed by Sidak's test, and qRT-PCR data using two-way ANOVA followed by Tukey's test (α=0.05). Results Contamination by microorganisms led to the development of apical periodontitis, characterized by the recruitment of inflammatory cells and bone tissue resorption, whereas inoculation of LPS induced inflammatory cells recruitment without bone resorption. Both stimuli induced mRNA expression for cyclooxygenase-2 and 5-lipoxygenase enzymes. Expression of prostaglandin E 2 and leukotriene B 4 cell surface receptors were more stimulated by LPS. Regarding nuclear peroxisome proliferator-activated receptors (PPAR), oral contamination induced the synthesis of mRNA for PPARδ, differently from inoculation of LPS, that induced PPARα and PPARγ expression. Conclusions Contamination of the root canals by microorganisms from oral cavity induced the development of apical periodontitis differently than by inoculation with LPS, characterized by less bone loss than the first model. Regardless of the model used, it was found a local increase in the synthesis of mRNA for the enzymes 5-lipoxygenase and cyclooxygenase-2 of the arachidonic acid metabolism, as well as in the surface and nuclear receptors for the lipid mediators prostaglandin E2 and leukotriene B4.

Effects of 5-lipoxygenase gene disruption on inflammation, osteoclastogenesis and bone resorption in polymicrobial apical periodontitis.

OBJECTIVES: To investigate the regulation of inflammatory and osteoclastogenic signaling by 5-lipoxygenase (5-LO) in apical periodontitis induced by oral contamination of dental root canals in mice. DESIGN: Apical periodontitis was induced in 5-lipoxygenase enzyme knockout (129-Alox5tm1Fun) and 129 wild-type mice (n = 96) by exposure of the dental root canal to the oral cavity. After 7, 14, 21, and 28 days, the animals were euthanized and the tissues removed (n = 12 teeth per period) for histopathological and histometric analyses (hematoxylin and eosin [HE]), evaluation of osteoclastogenic activity (tartrate-resistant acid phosphatase enzyme [TRAP]), and determination of inflammatory and osteoclastogenic signaling (qRT-PCR). RESULTS: Oral contamination of dental root canals induced recruitment of neutrophils and osteoclasts to the periodontal ligament, resulting in bone resorption. Absence of 5-LO did not impair neutrophil recruitment while osteoclastic formation was increased. Nonetheless, early bone resorption progressed similarly to lesions in wild-type animals. Interestingly, in the absence of 5-LO, the synthesis of mRNAs for cytokines, chemokines, and their receptors was significantly reduced while that of regulators of osteoclastogenesis (RANK, RANKL, and OPG) was increased in comparison with the corresponding levels in wild-type animals. CONCLUSIONS: The 5-LO pathway plays a role in the stimulation of inflammatory mediator synthesis and inhibition of osteoclastogenesis in apical periodontitis in mice. However, the paradoxical inflammatory-osteoclastogenic signaling did not impair inflammatory cell recruitment and bone resorption during early development of the disease.

Root canal contamination or exposure to lipopolysaccharide differentially modulate prostaglandin E 2 and leukotriene B 4 signaling in apical periodontitis

Abstract Purpose To evaluate the kinetics of apical periodontitis development in vivo , induced either by contamination of the root canals by microorganisms from the oral cavity or by inoculation of bacterial lipopolysaccharide (LPS) and the regulation of major enzymes and receptors involved in the arachidonic acid metabolism. Methodology Apical periodontitis was induced in C57BL6 mice (n=96), by root canal exposure to oral cavity (n=48 teeth) or inoculation of LPS (10 µL of a suspension of 0.1 µg/µL) from E. coli into the root canals (n= 48 teeth). Healthy teeth were used as control (n=48 teeth). After 7, 14, 21 and 28 days the animals were euthanized and tissues removed for histopathological and qRT-PCR analyses. Histological analysis data were analyzed using two-way ANOVA followed by Sidak's test, and qRT-PCR data using two-way ANOVA followed by Tukey's test (α=0.05). Results Contamination by microorganisms led to the development of apical periodontitis, characterized by the recruitment of inflammatory cells and bone tissue resorption, whereas inoculation of LPS induced inflammatory cells recruitment without bone resorption. Both stimuli induced mRNA expression for cyclooxygenase-2 and 5-lipoxygenase enzymes. Expression of prostaglandin E 2 and leukotriene B 4 cell surface receptors were more stimulated by LPS. Regarding nuclear peroxisome proliferator-activated receptors (PPAR), oral contamination induced the synthesis of mRNA for PPARδ, differently from inoculation of LPS, that induced PPARα and PPARγ expression. Conclusions Contamination of the root canals by microorganisms from oral cavity induced the development of apical periodontitis differently than by inoculation with LPS, characterized by less bone loss than the first model. Regardless of the model used, it was found a local increase in the synthesis of mRNA for the enzymes 5-lipoxygenase and cyclooxygenase-2 of the arachidonic acid metabolism, as well as in the surface and nuclear receptors for the lipid mediators prostaglandin E2 and leukotriene B4.

Periapical bone response to bacterial lipopolysaccharide is shifted upon cyclooxygenase blockage.

OBJECTIVES: Infection, inflammation and bone resorption are closely related events in apical periodontitis development. Therefore, we sought to investigate the role of cyclooxygenase (COX) in osteoclastogenesis and bone metabolism signaling in periapical bone tissue after bacterial lipopolysaccharide (LPS) inoculation into root canals. METHODOLOGY: Seventy two C57BL/6 mice had the root canals of the first molars inoculated with a solution containing LPS from E. coli (1.0 mg/mL) and received selective (celecoxib) or non-selective (indomethacin) COX-2 inhibitor. After 7, 14, 21 and 28 days the animals were euthanized and the tissues removed for total RNA extraction. Evaluation of gene expression was performed by qRT-PCR. Statistical analysis was performed using analysis of variance (ANOVA) followed by post-tests (α=0.05). RESULTS: LPS induced expression of mRNA for COX-2 (Ptgs2) and PGE2 receptors (Ptger1, Ptger3 and Ptger4), indicating that cyclooxygenase is involved in periapical response to LPS. A signaling that favours bone resorption was observed because Tnfsf11 (RANKL), Vegfa, Ctsk, Mmp9, Cd36, Icam, Vcam1, Nfkb1 and Sox9 were upregulated in response to LPS. Indomethacin and celecoxib differentially modulated expression of osteoclastogenic and other bone metabolism genes: celecoxib downregulated Igf1r, Ctsk, Mmp9, Cd36, Icam1, Nfkb1, Smad3, Sox9, Csf3, Vcam1 and Itga3 whereas indomethacin inhibited Tgfbr1, Igf1r, Ctsk, Mmp9, Sox9, Cd36 and Icam1. CONCLUSIONS: We demonstrated that gene expression for COX-2 and PGE2 receptors was upregulated after LPS inoculation into the root canals. Additionally, early administration of indomethacin and celecoxib (NSAIDs) inhibited osteoclastogenic signaling. The relevance of the cyclooxygenase pathway in apical periodontitis was shown by a wide modulation in the expression of genes involved in both bone catabolism and anabolism.

Genetic Polymorphisms in RANK and RANKL are Associated with Persistent Apical Periodontitis.

INTRODUCTION: The outcome of root canal treatment has been reported as intimately related to the host response. Genetic polymorphisms might be associated with apical periodontitis repair. The aim of this study was to evaluate the association between receptor activator of nuclear factor kappa B (RANK), receptor activator of nuclear factor kappa B ligand (RANKL), and osteoprotegerin (OPG) genetic polymorphisms with persistent apical periodontitis (PAP) in Brazilian subjects. METHODS: Subjects with at least 1 year of follow-up after nonsurgical root canal therapy were recalled. Sixty-four subjects with signs/symptoms of PAP and 86 subjects with root canal-treated teeth exhibiting healthy periradicular tissues (healed) were included. Genomic DNA was extracted from saliva and used for RANK (rs3826620), RANKL (rs9594738), and OPG (rs2073618) genotyping by real-time exact tests, and odds ratio were implemented using Epi Info 3.5.2 (Centers for Disease Control and Prevention, Atlanta, GA). A logistic regression analysis was also performed using the time of follow-up as the covariate. All tests were performed with an established alpha of 0.05 (P = .05). RESULTS: An association between allele distribution and the polymorphism in RANK was observed. Subjects who carry the T allele had a lower risk of having PAP (P < .05). In RANKL polymorphism, the genotype distribution was statistically significant different between the PAP and healed groups (P = .05). The time of follow-up was associated with PAP (P < .05). In the logistic regression analysis using time as a covariant, RANK (P < .05) and RANKL (P < .05) were associated with PAP. The polymorphism rs2073618 in OPG was not associated with PAP (P > .05). CONCLUSIONS: These findings suggest that polymorphisms in RANK and RANKL genes are associated with PAP.

Examination of OPG, RANK, RANKL and HIF1A polymorphisms in temporomandibular joint ankylosis patients.

PURPOSE: To evaluate the association between polymorphisms in genes that regulate bone metabolism, such as OPG, RANK, RANKL, and HIF1A, in patients with temporomandibular joint (TMJ) ankylosis. METHODS: The sample consisted of 181 individuals, the study included 17 individuals with TMJ ankylosis and 164 controls. DNA was extracted from buccal epithelial cells. The genotyping of genetic polymorphisms in OPG (rs2073618), RANK (rs3826620), RANKL (rs9594738), and HIF1A (rs2301113 and rs2057482) was performed by real-time PCR using TaqMan™ technology (Applied Biosystems). The data were subjected to statistical analysis with a level of significance of 0.05. RESULTS: The OPG (rs2073618) polymorphism was associated with TMJ ankylosis, both in the additive model and in the dominant model (p < 0.05). In the additive model, when the individuals carried the CC genotype, they presented as 10.80 times more likely to develop the condition (p = 0.03). In the dominant model, individuals that carried at least one C allele were 5.76 times more likely to have TMJ ankylosis, than those with the G allele (p = 0.01). CONCLUSION: The polymorphism rs2073618 of OPG is a possible marker that is associated with the risk of manifestation of TMJ ankylosis.

Influence Of Genetic Polymorphisms In Genes Of Bone Remodeling And Angiogenesis Process In The Apical Periodontitis.

Persistent apical periodontitis (AP) is a situation involving an inflammatory and immune response caused mainly by anaerobic polymicrobial infection of the root canal system and the outcome and follow-up of the root canal treatment has been reported as intimately related to host response. The apical periodontitis repair might be associated with genetic polymorphisms. This study aimed to evaluate the association between HIF1A genetic polymorphisms (rs2301113 and rs2057482) with PAP in Brazilian patients. Subjects with at least 1 year of follow-up after root canal therapy (RCT) were recalled. Sixty-four subjects with signs/symptoms of PAP and 84 subjects with root canal-treated teeth exhibiting healthy perirradicular tissues (healed) were included. Genomic DNA was extracted from saliva and used for HIF1A genotyping by real-time PCR. Genotype and allele frequencies were compared by c2 or Fisher's exact tests and odds ratio was implemented, using Epi Info 3.5.2. All tests were performed with an established alpha of 0.05. There was no association between allele and genotype distribution for HIF1As polymorphisms and PAP (p>0.05). The genetic polymorphisms in HIF1A were not associated with persistent apical periodontitis.