Microscopic qualitative evaluation of fixation time and decalcification media in rat maxillary periodontium

Qualitative Histological Evaluation of Various Decalcifying Agents on Human Dental Tissue

OBJECTIVE

 Dental hard tissue is among the hardest tissue of humans because it contains high amounts of inorganic substances. This leads to difficulty in preparing histological sections for histopathological examination. Acid and chelating agents are generally used to decalcify teeth. We aimed to compare the histological quality of teeth decalcified with various calcifying agents including 5% nitric acid, 50% formic acid with 20% sodium citrate (Anna Morse solution), 10% formic acid, commercial solution, and 14.4% neutral EDTA.

MATERIALS AND METHODS

 Freshly extracted premolar teeth were fixed and submitted for decalcification using different agents. Histological examination was qualitatively evaluated for tissue integrity and staining quality.

RESULTS

 Dentin integrity of teeth decalcified with all decalcifying agents did not show any statistical differences except that with the formic acid, whereas cementum integrity decalcified with neutral EDTA showed a superior score compared with other agents. Tissue integrity and staining quality of dental pulp cells were the best decalcified with neutral EDTA or Anna Morse solution.

CONCLUSION

 Our findings demonstrated that EDTA and Anna Morse solution gave a similar efficiency in the preservation of tissue integrity while Anna Morse solution may be recommended as a decalcification agent in routine use due to the more satisfying decalcification time than EDTA.

Interactions between lipid source and vitamin A on broiler performance, blood parameters, fat and protein deposition rate, and bone development

A total of 2622 male broilers were distributed in a 2 × 5 factorial design, using 2 lipid sources (soybean oil and palm fat), 5 levels of vitamin A supplementation (0, 3,000, 6,000, 12,000, and 24,000 IU kg⁻¹), with 10 replicates, and also 1 control diet (CD) for each lipid source used (7 replicates), each experimental unit being composed of 23 birds. During the first 21 d (how were the birds fed) and from 22 to 42 d of age, a redistribution of the treatments was carried out in a 2 × 2 × 5 factorial design: half of the repetitions of each treatment received the diet of the initial treatment, and the others received the CD with its type of lipid source. In the phase from 1 to 21 d of age, the effect of lipid source on feed intake (FI) and feed conversion ratio (FCR), and the effect of vitamin supplementation on FI and weight gain (WG) were observed, with a quadratic response for both variables. At 42 d of age, the lipid source and vitamin A level influenced the FI, whereas the WG and FCR showed interactions between period and the level of vitamin A supplementation. Neither lipid source resulted in blood parameters out of the typical pattern for birds, and the same was observed in relation to dietary vitamin A supplementation. From 1 to 21 d of age, a vitamin A supplementation of 15,585 IU kg⁻¹ was estimated, and at 42 d, 15,527 IU kg⁻¹ and 15,148 IU kg ⁻¹ were estimated for the periods 1 to 21 d and 1 to 42 d, respectively.

Evaluation of bone marrow preparations and sections of teeth prepared with modified Bouin's solution

The quality of bone marrow preparation and sections of teeth depends on the preparation method. We investigated the posterior mandibles of male rats that were processed using a modified Bouin's solution (MBS) and stained with Harris' hematoxylin and eosin, and the results were compared to a routine decalcification process using 5% formal nitric acid. We found that MBS was applicable to both soft and hard components in bone tissues and sections of teeth. MBS provided good decalcification, which facilitated sectioning. The bone marrow specimens treated with MBS exhibited clearly distinguishable hematopoietic cells, clear tissue integrity and good cell preservation. Treatment with 5% formal nitric acid for 5 days caused degeneration, poor differentiation and poorer staining of hematopoietic components, and deteriorated soft and solid tissues in bone and sections of teeth compared to MBS treatment. MBS preserved cell and tissue integrity and good staining quality. MBS can be used for rapid preparation and diagnosis for pathology and toxicity studies.

Tibiotarsus bone characteristics and tibial dyschondroplasia incidence of broilers fed diets supplemented with leucine and valine

Two experiments were conducted to study the effect of standardized ileal digestible (SID) leucine and valine levels on tibiotarsus bone characteristics and the incidence of tibial dyschondroplasia of broilers from day 1 to 21 (Experiment I) and day 21 to 42 post-hatch (Experiment II). Each experimental phase was evaluated independently. In both experiments, a total of 1,500 one-day-old Cobb 500 male broiler chickens were distributed in a completely randomized design 5 × 5 factorial arrangement for a total of 25 treatments. The SID leucine and valine levels were ranged from 10.0 to 19.6 g/kg, and 6.0 to 12.0 g/kg from day 1 to 21 post-hatch, respectively, while day 21 to 42 post-hatch ranged from 10.0 to 18.0 g leucine/kg, and 5.2 to 11.2 g valine/kg. Serum calcium and phosphorus, bone concentrations of calcium, phosphorus and ash, diameter and Seedor index of the tibiotarsus were not affected (p > .05) by the treatments at 21 or 42 days of age. There was an interaction (p ≤.06) between the SID levels of leucine and valine on tibiotarsus breaking strength at 21 days, but not at 42 days of age (p > .05). Tibiotarsus breaking strength was maximized in broilers from day 1 to 21 with the dietary levels of leucine and valine at 14.2 and 9.0 g/kg respectively. Dietary leucine levels reduced linearly (p < .05) the hypertrophic zone of tibiotarsus cartilage at 21 days of age. Therefore, leucine and valine supplementation interact positively on bone strength of broilers from day 1 to 21 post-hatch. Leucine can be a useful amino acid for reducing the hypertrophic cartilage zone in broilers from day 1 to 21, but not from day 21 to 42 post-hatch.

Comparison of Different Decalcification Methods Using Rat Mandibles as a Model

Selection of decalcification agents is an essential consideration when processing mineralized tissues because the integrity and immunohistochemical characteristics of the tissues may be affected. Here, we report results obtained from the decalcification of rat mandibles using 10% ethylenediaminetetraacetic acid (EDTA) at room temperature (RT), 10% EDTA at 37C, 5% nitric acid, and 10% formic acid at RT. Decalcification endpoints were determined by microcomputed tomography. Morphological preservation and antigenicity were evaluated by hematoxylin and eosin staining and immunohistochemistry. Decalcification of the anterior and posterior portions of the mandible took 220 and 191 hr in 10% EDTA RT, 102 and 73 hr in 10% EDTA 37C, 13.5 and 4.3 hr in 5% nitric acid, and 140 and 36 hr in 10% formic acid, respectively. Decalcification in 10% EDTA at 37C was accelerated, but 10% EDTA at RT provided optimal results for immunohistochemistry and cellular and structural details. Decalcification using 5% nitric acid was accomplished in the shortest time and exhibited good cellular and architectural morphology, whereas 10% formic acid was suboptimal with respect to tissue and cellular morphology. Despite being the slowest method, EDTA at RT is still the recommended method for decalcifying mineralized tissues; however, if rapid decalcification is needed, 5% nitric acid is the best option, yielding acceptable tissue integrity and speed.

Driving the Mineral out Faster: Simple Modifications of the Decalcification Technique

INTRODUCTION

Quicker decalcification is essential for faster diagnosis of hard tissue pathology. Heat and mechanical agitation are known to hasten decalcification.

AIM

To compare the rate of decalcification, cellular and staining characteristics of decalcified specimens of bone and teeth by using the conventional method (10% formal formic acid), heating to 45(o)C and by physical agitation with magnetic stirrer.

MATERIALS AND METHODS

Weight-matched samples of caprine-origin bone (n=15) and teeth (n=15) were decalcified using three methods namely: a) Gooding and Stewart's fluid; b) Gooding and Stewart's fluid heated to 45(o)C for 6 hours daily; and c) Gooding and Stewart's fluid agitated using a magnetic stirrer for 6 hours daily. Non-lesional skin tissue samples were placed along with each specimen. End point of decalcification (chemical test) was noted; 4 micron sections were taken and stained with H&E.

STATISTICAL ANALYSIS

Differences in rate of decalcification and staining characteristics were assessed by Kruskal Wallis test and chi-square test respectively.

RESULTS

Hard tissues decalcified faster with stirring and heating methods. The amount of osteocyte retraction noted in bone was significantly reduced in the stirring method. In tooth specimens, modified techniques resulted in poorer nuclear-cytoplasmic contrast of pulp cells. Heating affected the odontoblast layer. Soft tissues exhibited higher eosinophilia in stirring and conventional methods, whereas nuclear-cytoplasmic contrast and chromatin staining was poorest in heating and conventional methods.

CONCLUSION

Physical agitation of decalcifying fluid may be recommended while maintaining satisfactory quality of tissue morphology and staining.

Efficiency of different decalcification protocols for nasal osseous structures in a rat experimental model of allergic rhinitis, and their effects on epithelial histology: an attempt at standardization

INTRODUCTION

Decalcification of osseous specimens is required for histological analysis; this however may cause tissue damage. In rodent models of allergic rhinitis (AR), epithelial histologic assessment necessitates prior decalcification of the nasal osseous structures. However, respiratory epithelium is highly susceptible to damage, and rat nasal architecture is elaborate and its sectioning is challenging. Nevertheless, decalcification is not standardized in experimental AR. We therefore undertook this task, in order to reduce experimental bias.

METHODS

Six-to-eight week-old Wistar rats underwent an AR protocol. Subsequently, nasal structures were decalcified in the following mediums: (i) formic acid 10% for 5 and 20 days; (ii) formic acid 15% for 5 and 15 days; (iii) Morse Solution for 5 and 20 days and (iv) EDTA for 20 and 40 days. Decalcification efficiency/speed was evaluated via radiographic analysis. Furthermore, specimens were stained with hematoxylin and eosin and assessed for preservation of epithelial features.

RESULTS

Specimens were appropriately decalcified in 5 days in the formic acid-based mediums and in 20 days in EDTA with minimal epithelial damage. EDTA for 40 days had no unacceptable adverse effects; conversely, 15 and/or 20 days in acid-based agents provided no extra benefit for decalcification and were detrimental to the epithelium.

CONCLUSIONS

EDTA treatment for 20 days is appropriate for decalcification of nasal structures in rat models of allergic rhinitis; further incubation preserves epithelial integrity but is not required. When urgency is a factor, formic-acid-based decalcification for 5 days yields acceptable results.

Histological processing of teeth and periodontal tissues for light microscopy analysis

It is possible to obtain histological preparation of teeth and periodontium with satisfactory levels of quality by means of routine histological techniques, since specific cares are implemented during the sample processing. The formation of access ducts for the quick penetration of the fixative solution, the complete removal of the demineralizing agent and the increase of the time of dehydration, clearing, and paraffin embedding are some of these cares. A variety of fixing and demineralizing solutions have been proposed in the literature for teeth and periodontium processing. The author's' experience along the years demonstrated the possibility of satisfactory results with 10% buffered neutral formalin as fixative solution and 10% pH 7.3 EDTA as demineralizing solution. Sections of 6 μm in thickness obtained from paraffin-embedded samples, stained with hematoxylin and eosin, comply with the most morphological and morphometric evaluations. Besides, this routine protocol allows the use of serial sectioning for more specific techniques such as histochemical and immunohistochemical analyses, which are suitable for cellular constituent and extracellular matrix evaluation of teeth and periodontium. For the study of mineralized phases of isolated human teeth, ground sections can be obtained by the cutting-grinding technique. Though it is a recognized method of study, there are some technical difficulties involved, which are little exploited in the literature. This chapter presents a detailed cutting-grinding protocol for the histological evaluation of undecalcified isolated teeth and routine histology, which can be easily reproduced in any research or teaching support laboratory.