Histological evaluation of therapy using a calcium hydroxide dressing for teeth with incompletely formed apices and periapical lesions.

Periapical tissue response was evaluated histologically in teeth of 6-month-old dogs with incomplete root formation and periapical lesions in order to compare the effects of two calcium hydroxide-containing pastes prepared with different vehicles on induced root apex formation and repair of the periapical region. A group of teeth with no root canal dressing was used as control. After induction of the periapical lesion, the root canals were instrumented and filled with one of the two pastes (Calen and Calasept), which were renewed monthly for 90 days. At the end of the follow-up period (3 months), the animals were killed. Block sections from the actual areas were dissected free and prepared for histopathological analysis. Both calcium hydroxide pastes helped induce apical sealing and repair of the region, but the Calen paste yielded better results than Calasept. The induced mineralized tissue was predominantly of the cementoid type after the use of both pastes, but the inflammatory infiltrate was significantly less intense with the use of the Calen paste. In the control group, the absence of a root canal dressing impaired the process of periapical repair and yielded no apical root closure in any of the cases analyzed.

Histopathological observations of periapical repair in teeth with radiolucent areas submitted to two different methods of root canal treatment.

Dogs' teeth with induced chronic periapical periodontitis were treated endodontically by two different methods, and the results were compared. A total of 40 root canals from the upper and lower premolars of two dogs were prepared chemomechanically. In method 1, a high-concentration (5.25%) hypochlorite solution was used during the instrumentation of the root canal, and an antibacterial dressing was applied between sessions, followed by filling of the root canal. In method 2, a low-concentration (0.5%) sodium hypochlorite solution was used as an adjunct to mechanical debridement, and the root canal was filled during the same session. The histopathological results showed that method 1 led to better periapical repair than method 2.

Calcium hydroxide root canal sealers--histopathologic evaluation of apical and periapical repair after endodontic treatment.

Eighty root canals of the premolars of 4 dogs, with vital pulp, were instrumented and filled during the same session with the Sealapex, CRCS, Sealer 26, and Apexit sealers. The animals were sacrificed 180 days after root canal filling and their maxillae and mandibles were removed and fixed in 10% formalin. After routine histologic processing, the sections were stained with hematoxylin-eosin and Mallory trichrome. Histopathologic analysis showed that Sealapex was the sealer that best permitted the deposition of mineralized tissue at the apical level and was the only sealer that provided complete sealing (37.5% of cases). With the use of Sealapex, no inflammatory infiltrate occurred and there was no reabsorption of mineralized tissues. In contrast, partial sealing and a moderate inflammatory infiltrate occurred with the use of CRCS. When Apexit and Sealer 26 were used the absence of sealing was frequent and active reabsorption of mineralized tissues occurred in most cases. The inflammatory infiltrate predominating with the use of Apexit was of the severe type, whereas with the use of Sealer 26 the inflammatory infiltrate was mild or absent.

Effect of different root canal sealers on periapical repair of teeth with chronic periradicular periodontitis.

Teeth with induced chronic periradicular periodontitis in dogs were root canal treated. After the biomechanical preparation, using K files and 5.25% sodium hypochlorite as the irrigant solution, all root canals were dressed with an antibacterial dressing based on calcium hydroxide, which was left in place for 7 days. After this time, the root canals were obturated with lateral condensation of cold gutta-percha with either a calcium hydroxide root canal filling material (Sealapex) or a zinc oxide-eugenol sealer (Fill Canal). After 270 days, histopathological analysis showed better apical and periapical repair in the teeth obturated with Sealapex (P < 0.05).

Histological evaluation of the response of apical tissues to glass ionomer and zinc oxide-eugenol based sealers in dog teeth after root canal treatment.

The object of the study was to compare two commercial root canal sealers: Ketac-Endo (a glass ionomer cement) and Fill Canal (a zinc oxide-eugenol cement). A total of 34 root canals from dog premolars with vital pulps were used. After instrumentation, the root canals were sealed with Ketac-Endo and Fill Canal cements using gutta-percha and a lateral condensation technique. After 270 days the animals were sacrificed with an anesthetic overdose and the maxillae and mandibles were removed and fixed in formalin for 48 h. After routine histological processing the sections were stained with hematoxylin-eosin and Mallory trichrome stains. Microscopic analysis revealed that Ketac-Endo cement presented better results than Fill Canal cement.

Tissue response to an epoxy resin-based root canal sealer.

The objective of the present study was to evaluate two different types of root canal sealers: AH Plus (an epoxy resin-based sealer) and Fill Canal (a zinc oxide-eugenol based sealer). A total of 34 root canals with vital pulp from dogs' premolars were used. After instrumentation, the root canals were filled with gutta-percha and AH Plus or gutta-percha and Fill Canal sealers using a classical technique of lateral condensation. After histological processing, the sections were stained with hematoxylineosin or Mallory's trichrome stain. Inflammatory cells or areas of necrosis were not associated with AH Plus. Hard tissue formation apically to the material was observed in 14 specimens. The Fill Canal sealer presented an inflammatory response of moderate intensity in the periapical region, mainly adjacent to the material.

Connective tissue responses to calcium hydroxide-based root canal medicaments.

AIM: The objective of the present study was to evaluate the tissue inflammatory response induced by calcium hydroxide pastes, with or without paramonochlorophenol and camphor. METHODOLOGY: Isogenic BALB/c mice were inoculated into the subcutaneous tissue with either 0.1 mL of a suspension of Calen, Calen with camphorated paramonochlorophenol, Calen with paramonochlorophenol, Calasept paste or phosphate-buffered saline (control). After 6, 12 and 24 h and 2, 3, 5, 7 and 15 days, three animals in each group were sacrificed and the excised lesions processed for histopathological evaluation of the inflammatory response. Events monitored and graded included the assessment of vascular congestion, oedema, haemorrhage, inflammatory infiltrate, necrosis and tissue repair. RESULTS: The pastes induced an inflammatory response at every observation period, although the intensity, duration and extension of inflammation varied. Calen paste always produced an initial short-term inflammatory response whilst the other pastes produced extended reactions. All pastes allowed repair to take place by the end of the experimental period, although the speed of this process varied between the materials. Calen presented the best biocompatibility; the phenolic compound caused greater tissue response, which was even more severe in the absence of camphor. Calasept paste was damaging and the repair process slower. CONCLUSIONS: All calcium hydroxide formulations caused an inflammatory response. The severity and longevity of the responses varied between pastes as a result of the various antiseptic agents. Although irritating, repair was apparent with all formulations.

Comparison of subcutaneous connective tissue responses among three different formulations of gutta-percha used in thermatic techniques.

A study of the subcutaneous connective tissue response of 24 white rats to three different formulations of gutta-percha was undertaken. The prepared specimens were examined under the light microscope after intervals of 7, 21, 60 and 120 days. The results showed identical tissue responses after the initial period of 7 days. However, after 120 days the gutta-percha supplied with the Ultrafil system presented mature granulation tissue with neither oedema nor vascular congestion, in contrast to the responses observed with the McSpadden and Obtura formulations.

Effect of intracanal dressings on repair and apical bridging of teeth with incomplete root formation.

Periapical repair and apical bridging were studied in dog's teeth with incomplete root formation and induced chronic periapical lesions treated with different dressings. A total of 75 root canals from the upper and lower premolars of 4 dogs approximately 6 months of age were chemo-mechanically prepared and filled with the following dressings: antibacterial dressing consisting of a calcium hydroxide+camphorated p-monochlorophenol paste applied for 7 days and followed by monthly renewed calcium hydroxide paste as temporary dressing at 30, 60 and 90 days (Group A); antibacterial dressing consisting of camphorated p-monochlorophenol alone for 7 days, followed by temporary dressing with calcium hydroxide paste renewed at 30, 60 and 90 days (Group B). A control group (Group C) received no dressings. Ninety days after the last calcium hydroxide paste (Groups A, B) and after the last irrigation/aspiration (Group C), the animals were killed, the maxillae and mandibles were removed, and the material submitted to routine histological processing and examination. Both root canal dressings, were of fundamental importance for apical repair and bridging. The apical bridging was predominantly complete in Group A, incomplete in Group B, and absent in Group C. The calcium hydroxide+camphorated p-monochlorophenol combination gave better results than camphorated p-monochlorophenol alone.

Can cocaine block the uptake of neurotoxin produced by Trypanosoma cruzi?

In the present study we describe the morphological and morphometric alterations induced by Trypanosoma cruzi (Bolivia strain) on the mice parotid gland, and the action of cocaine on the development of the gland of growing infected animals. The acinar cells of animals inoculated 28 d after birth showed reduced eosinophilia, greater chromatin condensation, reduced height, and basally dislocated nucleus. The area occupied by the acini was decreased and the nuclear volume was reduced. Reduced height of epithelial cells and decreased nuclear volume occurred in the striated and excretory ducts. The presence of lymphoplasmocyte infiltrates was also observed. The present results indicate delayed development of the infected mouse parotid gland. Our results indicate that cocaine perceptibly reduced the atrophy of the acinar cells and minimized the histopathological changes caused by T. cruzi in the parotid gland, in addition to significantly increasing the survival of infected animals. The presence of stroma with dilated capillaries and frequent inflammatory infiltrates showed that cocaine does not interfere with the inflammatory response.

Morphological and morphometric study of the alterations on young mouse parotid gland with subpatent Chagas' disease.

In the present study we describe the morphological and morphometric alterations induced by two Trypanosoma cruzi strains (strains Y and Bolivia) in the mouse parotid gland during the subpatent period of infection. The acinar cells of animals inoculated 27 d after birth showed reduced eosinophilia, greater chromatin condensation, reduced height, and basally dislocated nucleus. The area occupied by the acini was decreased (999.38 micron 2 to 546.76 micron 2) and the volume of the acinar cells was reduced (116.28 micron 3 to 63.28 micron 3). Reduced height (21.20 micron to 14.28 micron) and decreased nuclear volume (125.28 micron 3 to 77.28 micron 3) occurred in the striated ducts. In the excretory duct there was reduced nuclear volume (121.16 micron 3 to 76.14 micron 3) and decreased height of the epithelial cells (26.05 micron to 14.00 micron). The presence of lymphoplasmocyte infiltrates was also observed. The changes induced by the Bolivia strain were qualitatively similar to those induced by strain Y, but more severe in nature. The present results indicate that infection with T. cruzi induces delayed development of the mouse parotid gland during the subpatent phase.

[Morphologic and morphometric study of changes in the mouse parotid gland in the acute phase of Chagas' disease]. / Estudo morfológico e morfométrico das alterações da glândula parótida de camundongos na fase aguda da doença de Chagas.

In the present study we describe the morphological and morphometric alterations induced by Bolivia strain of the Trypanosoma cruzi in the mouse parotid gland during the acute period of infection. The acinar cells exhibit reduced eosinophilia, greater chromatin condensation, reduced height and consequent dislocation of the nucleus towards the basal pole. Then lumen is reduced. The ducts are dilated and lined with low cylindrical epithelium. The septa are wider. An intense lymphoplasmocytic infiltrate is present. Amastigotes was found in glandular acini cells, striated duct cells, inter and intralobular connective tissue, muscle walls of blood vessels, and inside the striated duct lumen.

[Comparative histological study of palatal mucosa in patients with and without complete dentures before and after insertion of new dentures]. / Estudo histológico comparativo da mucosa palatina em pacientes portadores e não portadores de próteses totais antes e após a instalação de novas proteses.

The authors verified histologically in 20 no dentates patients, the influence of complete dentures on the hard palate mucosa. The patients were divided in two groups: I. Patients that never used complete dentures; II. Patients that were using complete dentures when this research was realized. New prosthesis were made for each one of the 20 patients. Immediately before they received the new prosthesis and ninety days after this, biopsies were realized. The circunferencial pieces of the hard palate mucosa were fixed in formol 10% and coloured with Hematoxylin/Eosin and Mallory's Tricomic for histomorphologic analysis and measuring of the stratum corneum of the epithelium. It was made the statistical analysis and the results showed that: 1. In normal conditions, the utilization of the full dentures produces the reduce of the thickness of the stratum corneum. This was more observed in Group I. 2. The range difference of the thickness of the stratum corneum between the first and the second biopsies in the groups I and II (4.86 microns and 2.18 microns) were not statistically significant. 3. With the use of complete dentures the stratum corneum of the epithelium showed tendence to parakeratinization.