Topographical, diametral, and quantitative analysis of dentin tubules in the root canals of human and bovine teeth.

The aim of this study was to evaluate the number and the diameter of dentin tubules in root canals, in the cervical, middle, and apical thirds, of human and bovine teeth. Twenty-four single-rooted, human premolars were divided into four groups (n = 6): GH1, 10 to 15 years; GH2, 16 to 30 years; GH3, 31 to 45 years; and GH4, 46 to 80 years; and 24 bovine incisors were divided into four groups (n = 6): GB1, central; GB2, lateral first; GB3, lateral second; and GB4, lateral third. The crowns were removed from the specimens, which were then debrided, sectioned longitudinally in the vestibular-lingual direction, and submitted to ultrasonic cleaning. Scanning electron microscopic evaluations were made with 1,000x and 5,000x magnification. According to the root thirds, statistically significant differences were found both for the number and the diameter of dentin tubules, with the cervical third presenting the highest mean values for both specimen types. As regards the number of dentin tubules, it was observed that the bovine specimens presented a significantly higher mean value than the human specimens; this difference was not observed when the diameters of the two types were compared.

Clinical Investigation of Matrix Metalloproteinases, Tissue Inhibitors of Matrix Metalloproteinases, and Matrix Metalloproteinase/Tissue Inhibitors of Matrix Metalloproteinase Complexes and Their Networks in Apical Periodontitis.

INTRODUCTION: This clinical study investigated the levels of metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) and respective forms (MMP/TIMP complexes) in apical periodontitis to determine their networks in the development of clinical/radiographic features, thus quantifying the levels of endotoxins (lipopolysaccharides) present in primarily infected root canals with apical periodontitis. METHODS: Twenty primarily infected root canals with apical periodontitis were selected. The presence of pain on palpation, tenderness to percussion, and the size of the radiographic lesion were recorded. The levels of MMPs (MMP-1, -2, and -9), TIMPs (TIMP-1 and -2), and their MMP/TIMP complexes (MMP-1/TIMP-1, MMP-1/TIMP-2, MMP-2/TIMP-1, MMP-2/TIMP-2, MMP9/TIMP-1, and MMP-9/TIMP-2) present in the periapical interstitial fluid were measured using the enzyme-linked immunosorbent assay. The kinetic chromogenic LAL test was used to quantify endotoxins. RESULTS: A higher mean level of MMP-9 (968.35 ± 342.00 pg/mL) was followed by MMP-2 (894.00 ± 591.62 pg/mL) and MMP-1 (789.43 ± 342.83 pg/mL). The linear regression analysis revealed a positive association of MMP-1 with both MMP-2 and MMP-9 (all P < .001). TIMP-1 (481.79 ± 86.09 pg/mL) (24/24) was found in higher levels than TIMP-2 (206.45 ± 86.09 pg/mL) (P < .05), including a positive correlation of MMP-1 with both TIMP-1 and TIMP-2 (all P < .05). Higher mean levels of MMP1, -2, and -9 were found in teeth with larger-size radiolucent lesions (>7 mm) compared with smaller ones (≤7 mm) (all P < .01). Higher levels of MMP-1 decreased the chance of TTP, whereas MMP-9 (odds ratio = 0.97) increased the chance of pain on percussion (odds ratio = 1.01). Higher levels of endotoxins present in root canals were positively correlated with larger amounts of MMP -9 (P < .05). CONCLUSIONS: MMPs, TIMPs, and their complexes (MMP/TIMP) are involved in apical periodontitis by interacting with complex networks in the development of clinical features and the severity of bone destruction.

Microbiological profile resistant to different intracanal medications in primary endodontic infections.

INTRODUCTION: This clinical study aimed to determine the microbiological profile resistant to different intracanal medications in primary endodontic infections by using both microbiological culture and the checkerboard DNA-DNA hybridization technique. METHODS: Twenty primarily infected root canals were selected and then instrumented before being randomly divided into 2 groups according to the intracanal medications: calcium hydroxide (Ca[OH]2) or Ca(OH)2 + chlorhexidine (CHX). Samples were collected before and after root canal procedures, which consisted in submitting them to microbiological culture and processing them for checkerboard DNA-DNA hybridization. RESULTS: No differences were found between the Ca(OH)2 (99.98%) and Ca(OH)2 + CHX groups (99.76%) regarding the median percentage values for the reduction of cultivable bacteria. The most frequently detected species were Capnocytophaga ochracea (70%) and Fusobacterium nucleatum ssp. vincentii (70%) in the initial samples. After instrumentation, the most frequently detected species were E. faecium (60%). After root canal treatments using either Ca(OH)2 or Ca(OH)2 + CHX as intracanal medications, the most frequently detected species were F. nucleatum ssp. vincentii (90%) and Enterococcus faecium (40%), respectively. Both treatments significantly decreased the number of bacterial species compared with the initial sample. However, this reduction was significantly greater in the Ca(OH)2 + CHX group (P < .05). This difference was also observed when evaluating the total bacterial load (P < .05). CONCLUSIONS: The use of Ca(OH)2 associated with CHX as an intracanal medication showed better results by acting on gram-positive and gram-negative microorganisms although such an action to eradicate enterococci should also be sought.

Correlation between Volume of Apical Periodontitis Determined by Cone-beam Computed Tomography Analysis and Endotoxin Levels Found in Primary Root Canal Infection.

INTRODUCTION: This clinical study was conducted to correlate the levels of endotoxins and bacterial counts found in primary endodontic infection with the volume of periapical bone destruction determined by cone-beam computed tomography (CBCT) analysis. Moreover, the levels of bacteria and endotoxins were correlated with the development of clinical features. METHODS: Twenty-four root canals with primary endodontic disease and apical periodontitis were selected. Clinical features such as pain on palpation, pain on percussion, and previous episode of pain were recorded. The volume (cubic millimeters) of periapical bone destruction was determined by CBCT analysis. Endotoxins and bacterial samplings were collected by using sterile/apyrogenic paper points. Endotoxins were quantified by using limulus amebocyte lysate assay (KQCL test), and bacterial count (colony-forming units [CFU]/mL) was determined by using anaerobic culture techniques. Data were analyzed by Pearson correlation and multiple logistic regression (P < .05). RESULTS: Endotoxins and bacteria were detected in 100% of the root canal samples (24 of 24), with median values of 10.92 endotoxin units (EU)/mL (1.75-128 EU/mL) and 7.5 × 10(5) CFU/mL (3.20 × 10(5)-8.16 × 10(6) CFU/mL), respectively. The median volume of bone destruction determined by CBCT analysis was 100 mm(3) (10-450 mm(3)). The multiple regression analysis revealed a positive correlation between higher levels of endotoxins present in root canal infection and larger volume of bone destruction (P < .05). Moreover, higher levels of endotoxins were also correlated with the presence of previous pain (P < .05). CONCLUSIONS: Our findings revealed that the levels of endotoxins found in root canal infection are related to the volume of periapical bone destruction determined by CBCT analysis. Moreover, the levels of endotoxin are related to the presence of previous pain.

One-visit versus two-visit root canal treatment: effectiveness in the removal of endotoxins and cultivable bacteria.

INTRODUCTION: This clinical study was conducted to compare the effectiveness of 1-visit versus 2-visit root canal treatment in removing endotoxins and cultivable bacteria from primarily infected root canals. METHODS: Forty-eight primarily infected root canals were selected and randomly divided into 4 groups: G1, 1% NaOCl; G2, 2% chlorhexidine (CHX) gel; G3, 1% NaOCl + Ca(OH)2; and G4, 2% CHX gel + Ca(OH)2 (all, n = 12). G1 and G2 involved 1-visit treatment, whereas G3 and G4 involved 2-visit treatment with the placement of Ca(OH)2 medication for 14 days. Samples were collected before and after root canal procedures. A chromogenic LAL assay test was used to quantify endotoxins. Culture techniques were used to determine bacterial counts. RESULTS: Endotoxins and cultivable bacteria were detected in 100% of the initial samples. All treatment protocols were effective in reducing bacterial load from infected root canals: G1 (1% NaOCl, 99.97%), G2 (2% CHX gel, 99.75%), G3 (1% NaOCl + Ca(OH)2, 99.90%), and G4 (2% CHX gel + Ca(OH)2, 96.81%), respectively (P < .05). No differences were found in bacterial load reduction when comparing 1-visit and 2-visit treatment groups, irrespective of the irrigant tested (P > .05). Higher median percentage values of endotoxin reduction were achieved in the 2-visit treatment groups (G3, 98.01% and G4, 96.81%) compared with 1-visit treatment groups (G1, 86.33% and G2, 84.77%) (all P < .05). CONCLUSIONS: Both 1-visit and 2-visit root canal treatment protocols were effective in reducing bacteria and endotoxins, but they were not able to eliminate them in all root canals analyzed. Furthermore, 2-visit root canal treatment protocols were more effective in reducing endotoxins than 1-visit root canal treatment protocols.

Assessment of the apical seal of root canals using different filling techniques.

The aim of this study was to investigate the apical leakage of roots filled by three different gutta-percha techniques: lateral condensation, Tagger's hybrid and E&Q Master. Forty-two extracted single-rooted teeth were used. The coronal part of each tooth was removed and the root received biomechanical preparation using a 60-K file. The roots were randomly divided into three groups according to the technique of filling the root canal: Group I, lateral condensation; Group II, Tagger's hybrid; Group III, E&Q Master. The roots were submitted to dye leakage test with Rhodamine B for 7 days, using vacuum during the initial 30 min. The teeth were sectioned longitudinally and the leakage was measured in a linear fashion from apex to crown. Statistical analysis indicated that lateral condensation and E&Q Master techniques showed lower leakage than Tagger's technique (P = 0.0016). However, statistically no difference was found between lateral condensation and E&Q Master system techniques.