ORAL HEALTH EVIDENCE-BASED PRACTICE PROGRAM
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Title A Biopsy Is Necessary to Distinguish Pathological Findings Around Impacted Third Molars
Clinical Question In a 15-30 year old patient with a radiolucent lesion around an impacted third molar, would removal of the pericoronal tissue for histopathological examination help clinicians make a more accurate diagnosis, that potentially could be a serious pathological finding, instead of just assuming the radiolucency is innocuous?
Clinical Bottom Line Multiple clinically significant entities may appear as a radiolucent lesion around an impacted third molar. In order to determine a specific diagnosis, evidence supports excision of the pericoronal radiolucency, and submission of the tissue for histopathologic examination, as the most accurate way to distinguish the radiographic findings.
Best Evidence (you may view more info by clicking on the PubMed ID link)
PubMed ID Author / Year Patient Group Study type
(level of evidence)
#1) 22945737Kaushal/20122 females, ages 20 and 25 with impacted third molars selected for extractionCase report
Key resultsExtracted impacted third molars with a radiolucency less than 2.5 mm in size were found to exhibit pathological abnormalities, most of which were dentigerous cysts. During follow up, the radiographic appearance was inferior to histopathological examination of the excised tissue in determining whether or not the periocornonal tissue had transformed into a more clinically significant pathological entity.
#2) 24293941Wali/201130 patients with impacted third molars selected for extraction; 18-30 year age group with maximum follicular space of 2.5 mm.Prospective Cohort Study
Key resultsFollicular tissue in 7 out of 30 patients studied was found to represent a dentigerous cyst lined by stratified squamous epithelium, as opposed to a dental follicle (23%; 90% CI = 13.2-37.9; P<0.001). Further examination of the dentigerous cysts revealed 20% arising in 18-20 year olds (P value = 0.861) and 35.3% arising in 21-25 year olds (P value = 0.242). Radiographs were not sufficient in revealing the cystic pathology associated with the teeth examined, resulting in the necessity of excision of the pericoronal tissue in order to determine the definitive diagnosis.
#3) 24323536Avril/201311,725 panoramic radiographs over a 6 year period.Narrative Review
Key resultsAfter extensive review of radiolucent lesions in the mandible, the authors concluded that most radiographic findings are clinically insignificant. However, certain lesions, especially those around impacted third molars, may be aggressive or malignant. Excision of these lesions, with submission of the tissue for histopathologic examination, is the only way to ensure a specific diagnosis. An odontogenic keratocyst, unicystic ameloblastoma, and central mucoepidermoid carcinoma may radiographically resemble a dentigerous cyst and may be misdiagnosed if a clinician relies on radiographic appearance alone.
Evidence Search 1) radiographic[All Fields] AND appearance[All Fields] AND ("tooth, impacted"[MeSH Terms] OR ("tooth"[All Fields] AND "impacted"[All Fields]) OR "impacted tooth"[All Fields] OR ("impacted"[All Fields] AND "teeth"[All Fields]) OR "impacted teeth"[All Fields]) AND ("pathology"[Subheading] OR "pathology"[All Fields] OR "pathology"[MeSH Terms]) 2) ("dentigerous cyst"[MeSH Terms] OR ("dentigerous"[All Fields] AND "cyst"[All Fields]) OR "dentigerous cyst"[All Fields]) AND ("tooth, impacted"[MeSH Terms] OR ("tooth"[All Fields] AND "impacted"[All Fields]) OR "impacted tooth"[All Fields] OR "impacted"[All Fields]) AND ("molar, third"[MeSH Terms] OR ("molar"[All Fields] AND "third"[All Fields]) OR "third molar"[All Fields] OR ("third"[All Fields] AND "molars"[All Fields]) OR "third molars"[All Fields]) 3) radiolucent[All Fields] AND lesions[All Fields] AND ("mandible"[MeSH Terms] OR "mandible"[All Fields])
Comments on
The Evidence
Validity: Most reported evidence related to a dentigerous cyst transforming into more clinically significant lesion was written in the manner of Case Reports. Although no Randomized Control Trials, Systematic Reviews, or Meta-Analysis were found on this topic, the evidence collected encompassed a detailed search for validity. The Case Report showed that dentigerous cysts arose in the 15-30 year age group and the radiographic appearance of these cysts cannot be used to determine the specific type of pathology associated with the follicular tissue. The Prospective Cohort Study noted that over time, the reduced enamel epithelium in the dental follicles around impacted third molars had an increased potential to undergo squamous metaplasia. This squamous metaplasia may form the basis for the development of an odontogenic keratocyst, unicystic ameloblastoma, and central mucoepidermoid carcinoma. The Review Article provided an overview of 11,725 radiographs with clinically significant radiolucent lesions in the mandible. The radiographic appearance alone could not be used to determine the pathologic reason for the radiolucent lesions. The common finding in each of the three articles was that excision of a radiolucent lesion around an impacted third molar, with submission of the tissue for histopathologic examination, is necessary in order to establish a definitive diagnosis. Perspective: Based on the articles chosen for support, the consensus of excising radiolucent lesions around impacted third molars, and submitting the tissue for histopathologic examination, provides a way to bring clarity to the uncertain radiographic diagnosis. The evidence supports the current teaching guidelines in Oral Pathology at the University of Texas Health Science Center at San Antonio School of Dentistry. Further research should be conducted on this topic to prevent serious pathological findings from going undiagnosed.
Applicability Radiographic findings alone are not sufficient for a clinician to make an adequate diagnosis of a radiolucent lesion around an impacted third molar. Histopathologic examination of excised follicular tissue provides a definitive diagnosis, which can then be used to distinguish a dental follicle from a dentigerous cyst, or from other more clinically significant pathological entities. Clinicians must realize that several entities present as a radiolucency around an impacted third molar (e.g., dentigerous cyst, odontogenic keratocyst, unicystic ameloblastoma, and central mucoepidermoid carcinoma) and their radiographic appearance may be similar. Therefore, the only definitive way to establish a diagnosis is to excise the follicular tissue and submit it for histopathologic examination.
Specialty/Discipline (Oral Medicine/Pathology/Radiology) (General Dentistry) (Oral Surgery)
Keywords Impacted third molar, Dentigerous cyst, Radiolucency, Cystic pathology
ID# 2809
Date of submission: 03/17/2015spacer
E-mail goodwinkl@livemail.uthscsa.edu
Author Kristin Goodwin
Co-author(s)
Co-author(s) e-mail
Faculty mentor/Co-author Anne Jones, DDS
Faculty mentor/Co-author e-mail JONESAC@uthscsa.edu
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