scholarly journals A microscopic study on the intercanalar isthmuses of the maxillary premolars and associated iatrogenic cracks

2020 ◽  
Vol 25 (6) ◽  
pp. 2161-2167
Author(s):  
PAULA PERLEA ◽  
◽  
SUCIU IOANA ◽  
MIHAI CIOCARDEL ◽  
RUXANDRA IOANA BARTOK ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Microscopic Study ◽  
Root Canal ◽  
Microscopic Investigation ◽  
Moderate Intensity ◽  
Thin Sections ◽  
Tertiary Dentin ◽  
Straight Line ◽  
Maxillary Premolars ◽  
Root Surfaces

The purpose of this microscopic investigation, using stereomicroscopy and light transmited microscopy was to evaluate the configuration of the endodontic treated maxillary premolars, making correlations between the presence of the intercanalar isthmuses and also, to identify possible associated fracture lines. We also evaluated the thickness of the tertiary dentinal layer (irritation dentin layer). The study was based on microscopic investigation on thin sections on fragments or separate preparations resulting from 12 premolars that were clinically compromised. The tertiary dentin is deposited in response to irritations and moderate intensity injuries. As the tendency of crack propagation is directed to the areas corresponding to the root canal towards one of the root surfaces (which is the closest) the crackline – almost without exception, is more or less arched, without detecting an eventual crack in a straight line.

An Electron Microscopic Study of the Acute Effects of Hypothalamic Releasing Factors on the Anterior Pituitary Gland

1968 ◽  
Vol 26 ◽  
pp. 232-233
Author(s):  
P.W. Coates ◽  
E.A. Ashby ◽  
L. Krulich ◽  
A. Dhariwal ◽  
S. McCann
Keyword(s):  
Anterior Pituitary ◽  
Microscopic Investigation ◽  
Uranyl Acetate ◽  
Electron Microscopic Investigation ◽  
Electron Microscopic ◽  
Tissue Samples ◽  
Thin Sections ◽  
Dense Membrane ◽  
Membrane Bound ◽  
Releasing Factors

The morphologic effects on somatotrophs of crude sheep hypothalamic extract prepared from stalk-median eminence were studied by electron microscopy in conjunction with concurrently run bioassays performed on the same tissue samples taken from young adult male Sherman rats.Groups were divided into uninjected controls and injected experimentals sacrificed at 5', 15', and 30' after injection. Half of each anterior pituitary was prepared for electron microscopic investigation, the other half for bioassay. Fixation using collidine buffered osmium tetroxide was followed by dehydration and embedment in Maraglas. Uranyl acetate and lead citrate were used as stains. Thin sections were examined in a Philips EM 200.Somatotrophs from uninjected controls appeared as described in the literature (Fig. 1). In addition to other components, these cells contained moderate numbers of spherical, electron-dense, membrane-bound granules approximately 350 millicrons in diameter.

scholarly journals Lower First Permanent Molar with an Additional Root Diagnosis and Management

2019 ◽  
Vol 2019 ◽  
pp. 1-4
Author(s):  
Abdullah Mahmoud Riyahi
Keyword(s):  
Early Diagnosis ◽  
Sodium Hypochlorite ◽  
Root Canal ◽  
Three Dimensional ◽  
Operating Microscope ◽  
High Quality ◽  
New Techniques ◽  
Permanent Molar ◽  
Straight Line ◽  
Warm Vertical Compaction

Three rooted lower first permanent molar represents one of the main anatomical variants which is a treatment challenge of clinicians. This study is aimed at presenting a case of a lower first molar with an additional root that was diagnosed and managed successfully using new techniques in endodontics. Tooth #46 was diagnosed as a necrotic pulp with symptomatic apical periodontitis. Different angle radiographs were obtained, and they clearly showed three roots. The procedure was completed under magnification and illumination using an operating microscope. The access cavity was modified to achieve straight line access for all the canals. Careful step-by-step instrumentation was performed using flexible NiTi rotary files. The canals were irrigated using 6% sodium hypochlorite. Afterwards, three-dimensional obturation was completed using warm vertical compaction. Knowledge of the anatomy and an early diagnosis are required to achieve high-quality root canal treatment.

Root Surface Resorption in Two Cases of Rapid Maxillary Expansion

1982 ◽  
Vol 9 (1) ◽  
pp. 37-40 ◽  
Author(s):  
L. Odenrick ◽  
E. Lilja ◽  
K-F. Lindbäck
Keyword(s):  
Active Surface ◽  
Root Surface ◽  
Rapid Maxillary Expansion ◽  
Histological Investigation ◽  
Maxillary Expansion ◽  
Maxillary Premolars ◽  
Root Surfaces ◽  
Expansion Period

The purpose of the present investigation was to study the root surfaces of maxillary first premolars after rapid maxillary expansion. In one girl and one boy with posterior skeletal cross-bites and bimaxillary crowding, midpalatal expansion appliances anchored to the first maxillary premolars and molars were used. After the transversal expansion period all first premolars were examined radiographically and then extracted and investigated histologically. The histological investigation revealed active surface resorption of the maxillary first premolars.

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