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 »  Home  »  Endodontic Articles 9  »  Prevalence of different periapical lesions associated with human teeth and their correlation with the presence and extension of apical external root resorption
Prevalence of different periapical lesions associated with human teeth and their correlation with the presence and extension of apical external root resorption
Introduction - Materials and methods.

F.V.Vier & J. A. P. Figueiredo
Post-Graduate Programof Dentistry, ULBRA, Canoas, Brazil.

Following pulp necrosis, the root-canal system encourages the colonization and proliferation of microbes (Estrela & Figueiredo 1999). The low intensity, chronic stimulus provided by bacteria and their products allows for the maintenance of inflammation in the periapical region (Yanagisawa 1980, Lin et al.1984). Chronic periapical lesions bearinga proliferative character, represented by granulomas and periapical cysts, are the result of this process (Leonardo et al. 1998). The slow growth of these lesions results in bone resorption that is visible radiographically.
The precise nature of such lesions can only be determined histologically (Linenberg et al. 1964). However, true prevalence of each pathological condition is unclear. Cystic lesions have been reported to account for between 3.2% (Nair 1987) and 54% (Priebe et al. 1954) of apical lesions, and granulomas for between 45% (Lalonde & Luebke 1968) and 96.8% (Nair 1987). Some of this may be explained by differences in sample source and histological methods.
A number of chemical mediators of inflammation, including the cytokynes IL-1a, IL-1b, TNFa, prostaglandins and LPS, seem to be related to the pathogenesis of periapical lesions (Schein & Schilder 1975, Schonfeld et al. 1982, Burchett et al. 1988, Wang & Stashenko 1993a,b). These substances may stimulate root resorption in the same way that they stimulate bone resorption (Hammarstrom & Lindkog1992).
Although radiographic examination is an important resource in clinical diagnosis, it is rarely helpful in the diagnosis of small areas of external root resorption associated with teeth having apical periodontitis (Bhaskar & Rappaport1971, Ferlini Filho1999, Laux et al. 2000).
Irregular resorbed areas are frequently situated in sites that are not within the reach of root-canal instruments or medication and may act as niches for extraradicular bacterial colonization (Tronstad et al. 1990, Lomc¸ali et al.1996), besides causing technical problems for rootcanal treatment (Delzangles1989, Malueg et al.1996).
There are few reports correlating periapical lesions with external inflammatory root resorption (Delzangles 1989, Bohne 1990,Vier & Figueiredo 2000). The aim of this study was to evaluate the prevalence of different periapical lesions as well as to evaluate the presence and extension of apical external resorption and its association with different categories of disease.

Materials and methods.
The sample comprised 113 extracted human teeth with visible periapical lesions. These extracted teeth were obtained from the Public Dental Services in the state of Rio Grande do Sul, Brazil, where endodontic or restorative treatment is not provided. Some of the teeth were symptomatic, others were removed because the crown was completely compromised by dental caries. Care was taken to include only teeth with whole and intact periapical lesions.
The specimens were stored at room temperature in a solution of formaldehyde (10%, w/v), and radiographed to exclude previous root-canal treatment or incomplete root formation. Fifteen teeth were discarded, leaving a final sample of 98 teeth, amongst which six presented two lesions on separate roots. A total of 104 apical lesions and104 root apices were analyzed.
The periapical lesions were gently removed from the root apices and labeled before processing. Semi-serial sections (0.5 m at 0.5-mm intervals) of soft periapical lesions were stained with HE. The periapical lesions were classified as:

Noncystic lesions
  • Periapical granuloma: Lesions predominantly in filtrated by lymphocytes, plasma cells and macrophages, with or without epithelial remnants (Nair et al.1996), and covered by a capsule of collagen fibres. In these lesions, neutrophils were sparse forming no abscess microcavities or concentrated infiltrates.
  • Periapical abscess: Lesions with a distinct collection of neutrophils in the interior of a previously existent granuloma (Nair et al.1996). These were further categorized as 1 јabscess cavity occupying up to one third; 2 ј1/3-2/3; 3 _2/3 of the total area of the visualized lesion in the histological sections.
Cystic lesions
  • Periapical cyst: Lesions with a layer of stratified squamous epithelium a long a surface of sufficient quantity of conjunctive tissue to indicate a delineated cavity and surrounded by a slight fibrous capsule (Patterson et al.1964, Lalonde&Luebke1968, Lalonde1970,Nobuhara & Del Rio1993,White et al.1994).
  • Abscessed periapical cyst: Cysts containing pus-filled cavities were classed as1, 2 or 3 as above.
The histological sections were analysed by two blinded and previously calibrated observers, using 32, 100 and 400x magnification (Zeiss microscope, Thornwood, USA).
The diagnosis of each lesion was determined by considering all the histological sections. The presence of epithelium delineating a pathological cavity in one or more sections of a lesion characterized it as a periapical cyst. Classification of abscess severity was based on the section showing its largest dimension. Thereafter, the periapical lesions were grouped in two subgroups:
  • noncystic lesions: A1 - with absence or with a small abscess (periapical granuloma and abscess degree 1); A2 - with advanced abscess (periapical abscess degrees 2 and 3).
  • cystic lesions: B1-withabsence or with a small abscess (periapical cyst and abscessed cyst degree1); B2-with advanced abscess (abscessed cysts degree 2 and 3).
The apical portion of the root was cut perpendicular to the long axis with carborundum disc to favour placement on stubs. The root apices were submerged in a solution of 2.5% sodium hypochlorite for 3 h, dehydrated in an ascending sequence of alcohols (70, 90 and 99.96%, for 5 h in each), attached to the stubs with the apex up wards, and sputtered (Balzers, Liechtensten) with gold palladium, to a thickness of 150 A. Scanning electron microscopy was conducted using a PhilipsXL 20 (Eindhmoven, Netherlands) microscope, operating at 15 Kv. The areas that surrounded the apical foramina of the apices were imaged at 100_. The apical foramen occupied the central region of the video screen and was totally surrounded by the root. If a root presented more than one apical foramen, more than one image was obtained, so as to guarantee the analyses of all the foramina. SEM images were analysed separately by two blinded and previously calibrated observers.
The dental apices were classified depending on the presence or absence of external apical resorption, as well as to its extent:

Periforaminal resorption:
Periforaminal resorption was defined as the area of resorption not comprising the outline of the foramen, but the surrounding area. The degrees of severity 0-3 were employed when there was absence of resorption, resorption of up to 1/4, from 1/4 to1/2 and in more than1/2 of the area that surrounded or circumscribed the apical foramen, respectively.

Foraminal resorption:
Defined as the resorption within the outline or the perimeter of the foramen. The degrees of severity 0-3 were employed when there was absence of resorption, resorption of up to 1/4, from 1/4 to 1/2 and in more than1/2 of the area of the outline or the perimeter of the apical foramen, respectively.
Whenever a tooth presented with two or more apical foramina or had fused roots, the degree of final resorption measured was the foramen where the resorption was most severe.
Kappa coefficient was employed to evaluate the degree of agreement amongst the examiners, both in diagnosing the periapical lesions and in the presence and extension of periforaminal and foraminal external resorption.
The anova statistical test was used to evaluate the correlation between the histopathological diagnosis of the periapical lesions and the presence and extension of the external apical root resorption, followed by the Duncan test of multiple comparisons. Due to the ordinal nature of the data, the Kruskal-Wallis anova was also used. The frequencies observed in the groups were compared using the Chi-square test.