Delayed tooth replantation after root surface treatment with sodium hypochlorite and sodium fluoride: Histomorphometric analysis in rats

In cases of delayed tooth replantation, non-vital periodontal ligament remnants have been removed with sodium hypochlorite in an attempt to control root resorption. Nevertheless, reports of its irritating potential in contact with the alveolar connective tissue have been described. Therefore, this study evaluated the healing process on delayed replantation of rat teeth, after periodontal ligament removal by different treatment modalities. Twenty-four rats, assigned to 3 groups (n=8), had their upper right incisor extracted and left on the workbench for desiccation during 60 min. Afterwards, the teeth in group I were immersed in saline for 2 min. In group II, root surfaces were scrubbed with gauze soaked in saline for 2 min; and in group III, scrubbing was done with gauze soaked in 1% sodium hypochlorite solution. Thereafter, root surfaces were etched with 37% phosphoric acid and immersed in 2% acidulate-phosphate sodium fluoride solution, at pH 5.5. Root canals were filled with a calcium hydroxide-based paste and the teeth were replanted. The animals were sacrificed 60 days postoperatively and the pieces containing the replanted teeth were processed and paraffin- embedded. Semi-serial transversally sections were obtained from the middle third of the root and stained with hematoxylin and eosin for histomorphometric analysis. Data were analyzed statistically using Kruskal-Wallis and Dunn's tests. The results showed that root structure and cementum extension were more affected by resorption in group III (p<0.05). All groups were affected by root resorption but the treatment performed in group III was the least effective for its control. The treatment accomplished in groups I and II yielded similar results to each other.

Antimicrobial endodontic compounds do not modulate alkylation-induced genotoxicity and oxidative stress in vitro

Objective: To investigate if formocresol, paramonochlorophenol, or calcium hydroxide modulate the genotoxic effects induced by the oxidatively damaging agent hydrogen peroxide (H 2O 2) or the alkylating agent methyl methanesulfonate (MMS) in vitro by using single cell gel (comet) assay. Study design: Chinese hamster ovary (CHO) cells in culture were exposed directly to formocresol, paramonochlorophenol, or calcium hydroxide (adjusted to 100 μg/mL) for 1 hour at 37°C. Subsequently the cultures were incubated with increasing concentrations (0-10 μmol/L) of MMS in phosphate-buffered solution (PBS) for 15 minutes at 37°C or of H 2O 2 at increasing concentrations (0-100 μmol/L) in distilled water for 5 minutes on ice. The negative control cells were treated with PBS for 1 hour at 37°C. The parameter from the comet assay (tail moment) was assessed by the Kruskal-Wallis nonparametric test followed by a post hoc analysis (Dunn test). Results: Clear concentration-related effects were observed for the genotoxin-exposed CHO cells. Increase of MMS-induced DNA damage was not significantly altered by the presence of the compounds tested. Similarly, no significant changes were observed when hydrogen peroxide was used with the endodontic compounds evaluated. Conclusion: Formocresol, paramonochlorophenol, and calcium hydroxide are not able to modulate alkylation-induced genotoxicity or oxidative DNA damage as depicted by the single cell gel (comet) assay. © 2006 Mosby, Inc. All rights reserved.

Associação do hidróxido de cálcio e metronidazol no tratamento de dentes de cães com lesão periapical crônica

One of the primary objectives of endodontic treatment of teeth with pulp necrosis is the elimination of microorganisms from the root canal system, as effectively as possible, especially in cases with chronic periapical lesions. AIM: The purpose of this study was to analyze the response of the periapical tissue of dogs' teeth with chronic periapical lesions to endodontic treatment performed with utilization of metronidazole, calcium hydroxide, and an association of both as root canal dressings. METHODOLOGY: Forty root canals were submitted to pulpectomy and the root canals were kept exposed to the oral environment for 6 months. Then, they were submitted to biomechanical preparation and divided into 4 study groups with 10 specimens: group I - no root canal dressing; group II - calcium hydroxide; group III - metronidazole; group IV - calcium hydroxide associated to metronidazole. After 15 days, the root canals were filled with Fill Canal sealer. After 90 days, the animals were killed and the especimens processed for histological analysis. RESULTS: Calcium hydroxide dressing provided a significantly better outcome compared to other experimental groups (α = 0.01). Also, the results of the association of metronidazole and calcium hydroxide were similar to those observed for the metronidazole group. The worst results were obtained by the no root canal dressing group. CONCLUSION: The use of metronidazole alone or associated with Calcium hydroxide, did not improve periapical healing when compared to Calcium hydroxide dressing.

Histomicrobiologic aspects of the root canal system and periapical lesions in dogs' teeth after rotary instrumentation and intracanal dressing with Ca(OH)2 pastes

OBJECTIVE: The purpose of this study was to evaluate the distribution of microorganisms in the root canal system (RCS) and periapical lesions of dogs' teeth after rotary instrumentation and placement of different calcium hydroxide [Ca(OH)2]-based intracanal dressings. MATERIALS AND METHODS: Chronic periapical lesions were experimentally induced in 80 premolar roots of four dogs. Instrumentation was undertaken using the ProFile rotary system and irrigation with 5.25% sodium hypochlorite. The following Ca(OH) 2-based pastes were applied for 21 days: group 1 - Calen (n=18); group 2 - Calen+CPMC (n=20); group 3 - Ca(OH)2 p.a. + anaesthetic solution (n=16) and group 4 - Ca(OH)2 p.a.+ 2% chlorhexidine digluconate (n=18). Eight root canals without endodontic treatment constituted the control group. Histological sections were obtained and stained with Brown & Brenn staining technique to evaluate the presence of microorganisms in the main root canal, ramifications of the apical delta and secondary canals, apical cementoplasts, dentinal tubules, areas of cemental resorption and periapical lesions. The results were analyzed statistically by the Mann-Whitney U test (p<0.05). RESULTS: The control group showed the highest prevalence of microorganisms in all sites evaluated. Gram-positive cocci, bacilli and filaments were the most frequent morphotypes. Similar microbial distribution patterns in the RCS and areas of cementum resorption were observed in all groups (p>0.05). The percentage of RCS sites containing microorganisms in groups 1, 2, 3, 4 and control were: 67.6%, 62.5%, 78.2%, 62.0% and 87.6%, respectively. CONCLUSION: In conclusion, the histomicrobiological analysis showed that the rotary instrumentation and the different calcium hydroxide pastes employed did not effectively eliminate the infection from the RCS and periapical lesions. However, several bacteria seen in the histological sections were probably dead or were inactivated by the biomechanical preparation and calcium hydroxide-based intracanal dressing.

Biocompatibility of resin-based dental materials applied as liners in deep cavities prepared in human teeth

Background: Since only a few data have been published concerning the effects of resinous dental materials on the pulp-dentin complex, the aim of this study was to evaluate the biocompatibility of resin-based materials applied as liners in deep cavities prepared in duman teeth. Methods: After preparing class V cavities, the following dental materials were applied on the axial walls: group 1, Vitrebond™ (VIT; 3M ESPE); group 2, Ultra-Blend® Plus™ (UBP; Untradent); and group 3, Clearfil™ SE Bond (CSEB; Kuraray). In group 4 (control), the hard-setting calcium hydroxide cement Dycal (CH; Caulk/Dentsply) was used. The teeth extracted at 7 days or between 30 and 85 days after the clinical procedures were processed for histological evaluation. Results: For all the experimental and control groups, most of specimens exhibited no pulpal response or slight inflammatory reaction associated with slight tissue disorganization at 7-day period. Moderate inflammatory pulpal response occurred only in one tooth (RDT = 262 μm) of group 3 in which transdentinal diffusion of resin components was observed. Conclusion: The resin-based dental cements VIT and UBP as well as the bonding agent CSEB presented acceptable biocompatibility when applied in deep cavities prepared in sound human teeth. © 2006 Wiley Periodicals, Inc.

Cytotoxic effects of hard-setting cements applied on the odontoblast cell line MDPC-23

Objective: The present study evaluated the cytotoxic effects of hard setting applied on the odontoblastlike cells MDPC-23. Study design: Eighty round-shaped samples were prepared with the following experimental materials: calcium hydroxide, Vitrebond, RelyX Luting, and RelyX Unicem. The samples were placed in serum-free culture medium and incubated for 24 hours or 7 days at 37°C with 5% CO 2 and 95% air. The odontoblast cells were plated in the wells and incubated for 72 hours. After this period, the complete culture medium was replaced by the extracts obtained from every sample, and the methyltetrazolium assay was carried out to evaluate the cell metabolism. Results: For the 24-hour period, the experimental materials calcium hydroxide, Vitrebond, RelyX Luting, and RelyX Unicem decreased the cell metabolic activity by 91.52%, 81.14%, 78.17%, and 2.64%, respectively. For the 7-day period, calcium hydroxide, Vitrebond, RelyX Luting, and RelyX Unicem decreased the metabolic activity of the MDPC-23 cells by 91.13%, 87.27%, 79.04%, and 10.51%, respectively. Conclusion: RelyX Unicem presented the lowest cytopathic effects to the cultured odontoblast cell line. © 2007 Mosby, Inc. All rights reserved.

Conservative treatment of patients with periapical lesions associated with extraoral sinus tracts

This paper describes the clinical courses of three cases with extra-oral sinus tract formation, from diagnosis and treatment to short-term follow-up and evaluation. All teeth involved had periradicular radiolucent areas noted on radiographic examination and extra-oral sinus tracts appearing on the chin with exudation and unpleasant aesthetic appearance. The adopted treatment protocol included treating the sinus tract surface simultaneously with the root canal therapy. After root canal shaping using 5.25% sodium hypochlorite solution, calcium hydroxide-based pastes associated with different vehicles were inserted into the root canal for 4 months, and were changed monthly. All the sinus tracts healed in 7 to 10 days. The apical lesions were completely repaired in a maximum period of 24 months. The treatment adopted provided a complete healing of the periapical lesions in a short follow-up period. Surgical repair of the cutaneous sinus tract was therefore unnecessary. © 2007 The Authors. Journal compilation © 2007 Australian Society of Endodontology.

Periapical tissue healing after post space preparation with or without use of a protection plug and root canal exposure to the oral environment. Study in dogs

The purpose of this study was to evaluate the influence of coronal leakage on the healing of dogs' periapical tissues after root canal filling, post space preparation and protection or not with a temporary sealer plug. Forty root canals of dogs' teeth were instrumented and filled by the lateral condensation technique with gutta-percha points and Endomethasone or CRCS sealers. After post space preparation, the remaining filling material was protected or not with a plug of temporary Coltosol sealer and exposed to the oral environment for 90 days. Thereafter, the animals were sacrificed and the specimens were removed and prepared for histomorphological and histobacteriological analysis. The findings revealed 35% of microbial leakage in the groups without plugs and 15% of leakage in the groups with plugs. Statistical analysis showed that the use of a Coltosol plug improved significantly the histomorphological results regardless of the type of root canal sealer (p=0.05) and that CRCS and Endomethasone sealers showed similar results (p>0.05).

Evolution of the mechanical properties of a tropical soil stabilized with lime and ash of rice rind

The ash of rice rind is a pozzolanic material that reacts with the calcium hydroxide (Ca (OH)2) forming bonding composites, when finely worn out and in water presence. Considering this behavior, the objective of the present work was to evaluate the potential use of this residue in the enrichment of the content of pozzolanic materials of a tropical soil stabilized with a commercial hydrated lime. The laboratory testing program incorporated unconfined compression strength tests performed on the soil and on its mixtures with contents of 8% of lime enriched with 5 and 10% of ash of rice rind in relation to the soil dry mass. The results of the testing program supported that the use of the residue was effective in increasing the degree of reactivity of the soil that was also directly related with the increase in the ash content and the period of cure of the mixtures.

Antimicrobial analysis of chlorhexidine gel and intracanal medicaments against microorganisms inoculated in root canals

The aim of this paper was to evaluate the antimicrobial activity of 2% chlorhexidine gel (CLX) associated with various intracanal medicaments against Candida albicans and Enterococcus faecalis inoculated in root canals. Thirty six human single-rooted teeth were contaminated with C.albicans and E.faecalis. The canals were instrumented using 2% CLX gel and were divided into three groups according to the intracanal medicaments (ICM) used. Group 1: calcium hydroxide paste [Ca(OH)], Group 2: 2% chlorhexidine gel (CLX) and Group 3: 2% CLX gel + Ca(OH). The root canal collections were performed after 21 days of contamination (control collection), after instrumentation (1st collection), after 14 days of intracanal medicament (2nd collection) and 7 days after medicament removal (3rd collection). The microbiological samples were plated in culture media and incubated for 48 hours. The results were submitted to Kruskal-Wallis test (P ≤ 0.05). It was verified that the instrumentation with CLX reduced the number of CFU/ml significantly when compared with the confirmation collection (control). However, the use of the ICM was only capable to eliminate completely the microorganisms in the root canals without difference statistics between them. Although the use of 2% chlorherixidine gel reduces the number of microorganisms significantly, only the ICM calcium hydroxide and calcium hydroxide associated with chlorhexidine are able to eliminate these microorganisms completely.

Effect of zoledronic acid used in the root surface treatment of late replanted teeth: A study in rats

This study evaluated the use of zoledronic acid, a resorption inhibitor, as a medication for root resorption treatment of late replanted teeth. Twenty-four maxillary right central incisors of rats were avulsed and kept dry for 30 min. Then, the teeth were divided into 2 groups. In group I, root surface was treated with 2% sodium fluoride for 20 min; in group II, 10-6M zoledronic acid solution was used for 20 min. All root canals were filled with calcium hydroxide. Next, teeth were replanted in their respective sockets. After 15 and 60 days post-replantation, the animals were killed and the anatomic pieces were obtained and prepared for microscopic and morphometric analyses. The results showed that zoledronic acid was capable of limiting the occurrence of root resorption and preserving cementum resorption. Further research must be performed to confirm the use of zoledronic acid in root surface treatment of late replanted teeth.

Evaluation of tissue reaction, cell viability and cytokine production induced by Sealapex Plus

The aim of this study was to investigate the effects of mineral trioxide aggregate (MTA), Sealapex, and a combination of Sealapex and MTA (Sealapex Plus) on the reaction of subcutaneous connective tissue of rats, and on cell viability and cytokine production in mouse fibroblasts. The tissue reaction was carried out with dentin tubes containing the materials implanted in the dorsal connective tissue of rats. The histological analysis was performed after 7 and 30 days. Millipore culture plate inserts with polyethylene tubes filled with materials were placed into 24-well cell culture plates with mouse fibroblasts to evaluate the cell viability by MTT assay. ELISA assays were also performed after 24 h of exposure of the mouse fibroblasts to set material disks. Histopathologic examination showed Von Kossa-positive granules that were birefringent to polarized light for all the studied materials at the tube openings. No material inhibited the cell viability in the in vitro test. It was detected IL-6 production in all root-end filling materials. MTA and Sealapex Plus induced a slight raise of mean levels of IL-1β. The results suggest that Sealapex Plus is biocompatible and stimulates the mineralization of the tissue.

Effectiveness of castor oil extract on Escherichia coli and its endotoxins in root canals

The results of the present study showed a significant decrease in the number of E. coli in root canals (first collection) after irrigation with castor oil extract during biomechanical preparation. All medications tested in this study were able to eliminate E. coli in root canals; however, they could not neutralize endotoxins completely.

The challenges of treating a fused tooth

This paper describes and discusses the multidisciplinary treatment involving a permanent maxillary lateral incisor fused to a supernumerary tooth, both presenting pulp necrosis and periapical lesion. A 15-year-old male patient sought treatment complaining of pain, swelling and mobility on the maxillary right lateral incisor. After clinical and radiographic examination, root canal preparation was performed according to the crown-down technique and a calcium hydroxide dressing was placed for 15 days. The patient returned and the definitive endodontic filling was done with thermomechanical compaction of gutta-percha and sealer. After 18 months, clinical and radiographic examinations were carried out and no pain or swelling was reported. Two years after endodontic treatment, the patient returned for periodontal and cosmetic treatments. Nine months later, a cone-beam computed tomography (CBCT) revealed that the previously detected periodontal defect and periapical lesion were persistent. Apical endodontic surgery was indicated. The supernumerary tooth was removed, the communicating distal surface was filled and the surgical site received bioactive glass and demineralized bovine organic bone. The pathological tissue was submitted to histopathological examination and the diagnosis was periapical cyst. One year after the apical endodontic surgery, CBCT showed bone formation at maxillary lateral incisor apical area. Two years after the surgery, the restoration was replaced due to aesthetic reasons and periapical radiograph showed success after 5 years of treatment. A correct diagnosis and establishment of an adequate treatment plan resulted in a successful management of the case.

Composição química e degradabilidade ruminal de silagens da cana-de-açúcar tratada com aditivos químicos e bacteriano1

The objective of this trial was to evaluate the effect of the addition of chemical and bacterial additive in the ensiling of sugar cane (Saccharum officinarum L.) on chemical composition, pH, kinectic fraction and in situ degradation of nutritions components of silages. Five rumen-cannulated 1/2 Simental + 1/2 Zebu steers were allotted to a completely randomized design. The steers were placed in individual cages and they were fed with diets with 76% forage (%DM). Five silages were evaluated: control - sugar cane, no additives; urea - sugar cane + 0.5% of urea (wet basis); inoculant - sugar cane inoculated with LactoSilo® (390 g/40 t forage); NaOH - sugar cane + 1.0% of sodium hydroxide (wet basis); CaOH - sugar cane + 0.6% of calcium hydroxide (wet basis). The silage additives with sodium hydroxide showed the highest pH values before (11.20) and after (4.87) for silage. No differences were observed among the silages for dry matter (26.85), crude protein (5.25) and acid detergent fiber (57.21). Fractionation of dry matter and organic matter of silages showed similar behavior, with higher values of the soluble fraction (fraction A) for silages with sodium hydroxide (45.86 and 30.95%) and calcium hydroxide (29.47 and 26.13%). The use of sodium hydroxide allowed obtaining higher values for the degradation of cell wall components of silages from cane sugar. The potencial and effective degradability with 3, 5 and 8%/h of passage rate were respectively 88.44, 64.45, 56.73 and 49.83% for NDF and 82.57, 55.51, 46.72 and 38.83% for ADF, indicating that the use of sodium hydroxide as chemical additives can improve the nutritive value of cane sugar silage.