Indian Journal of Dental Research

: 2010  |  Volume : 21  |  Issue : 3  |  Page : 385--390

Histopathologic changes in soft tissue associated with radiographically normal impacted third molars

Vijayalakshmi S Kotrashetti1, Alka D Kale1, Sudhir S Bhalaerao2, Seema R Hallikeremath1,  
1 Department of Oral Pathology and Microbiology, KLE VK Institute of Dental Sciences and Hospital, Belgaum - 590 010, Karnataka, India
2 Department of Oral Pathology and Microbiology, D Y Patil Dental College and Hospital, Navi Mumbai, India

Correspondence Address:
Vijayalakshmi S Kotrashetti
Department of Oral Pathology and Microbiology, KLE VK Institute of Dental Sciences and Hospital, Belgaum - 590 010, Karnataka


Background: The incidence of impacted or embedded third molars accounts for approximately 98%. Since 1948, there are studies reporting pathological changes in an asymptomatic dental follicle. Controversy still exists for removal of asmptomatic impacted teeth. Hence, this study was performed to histologically evaluate soft tissue pathosis in the pericoronal tissues of impacted third molars with pericoronal radiolucency measuring up to 2.5 mm on orthopantomographs. Materials and Methods: Forty-one asymptomatic impacted third molars with follicular space of up to 2.5 mm on radiographs were included. The disimpacted teeth and the follicular tissues were obtained for histological examination. Results: Age of the patients ranged from 14 to 25 years. Of 41 tissues evaluated, histopathological reports of 18 follicles were suggestive of dentigerous cyst, two follicles showed odontogenic keratocyst, one follicle each of calcifying epithelial odontogenic cyst, ameloblastoma-like proliferation, odontogenic myxoma and odontogenic fibroma. Conclusion: This study showed 58.5% of asymptomatic cases with definite pathological changes. Hence, thorough clinical and radiographic examination should be carried out for all impacted third molars and the dental follicular tissue should be submitted for histopathological evaluation.

How to cite this article:
Kotrashetti VS, Kale AD, Bhalaerao SS, Hallikeremath SR. Histopathologic changes in soft tissue associated with radiographically normal impacted third molars.Indian J Dent Res 2010;21:385-390

How to cite this URL:
Kotrashetti VS, Kale AD, Bhalaerao SS, Hallikeremath SR. Histopathologic changes in soft tissue associated with radiographically normal impacted third molars. Indian J Dent Res [serial online] 2010 [cited 2021 Aug 1 ];21:385-390
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Removal of impacted third molars (3 rd molars) is a common procedure performed in oral surgery. Although indications for removal of 3 rd molars have generated much discussion in dentistry, there is still no general agreement about the need for surgical removal of asymptomatic fully impacted 3 rd molars. [1] Radiographic interpretations of impacted 3 rd molars without obvious diagnostic features are often assumed to be normal. Previous literature suggested that pericoronal radiolucency of <2.5 mm in width is nonpathologic. The reason for disimpaction of impacted teeth remains a controversy.

It is reported that 3 rd molars that are overdue for normal eruption but remain impacted may develop pathologies. The decision to remove an impacted tooth is less challenging when signs and symptoms of pathosis are present, but it is made more demanding when the patient is asymptomatic. Controversy exists over the prophylactic removal of asymptomatic impacted teeth. The National Institute of Health Consensus Development Conference on removal of third molars in 1979 developed criteria for the treatment of impacted teeth with pathosis, but no consensus was reached regarding the management of asymptomatic impacted teeth. However, the literature review suggests development of cystic lesions with long-term retained asymptomatic third molars. Girod et al. in 1993 presented three cases of long-standing impacted third molar, which developed cystic lesion over a period of 2-12 years. [2]

Histologically, dental follicle is referred to as condensed ectomesenchyme, limiting the dental papilla and encapsulating the dental organ characterized by fibrous connective tissue with reduced enamel epithelium, epithelial rests, myxoid tissue and calcification [3] . Reports in the literature discuss the prevalence of cyst and tumor development associated with impacted teeth. Clinical studies reported by the US National Institute of Health indicated that 1.5-13.3% of 3 rd molars were removed primarily due to cyst formation. [4] Some authors stated that cyst and tumor formation in the pericoronal area of the impacted teeth are rare and thus suggested that prophylactic removal of the impacted 3 rd molar is not necessary. [5],[6],[7] The fact that not all pericoronal cysts and tumors are obvious clinically and radiographically, removal of such lesions is not considered. In majority of the cases, the presence of cysts and tumors are not confirmed at the early stages, which can become hazardous subsequently. Attention should be directed to the natural history of these lesions and their effect on the need for the removal of impacted teeth. This study was carried out with an aim to evaluate the tissues lining the impacted teeth, which were otherwise asymptomatic.

 Materials and Methods

A prospective histological study of the dental follicles of the impacted third molars was carried out at the Department of Oral Pathology and Microbiology, Institute of Dental Sciences, KLE University, Belgaum, after obtaining institutional ethical clearance. The study group comprised of 30 subjects having at least one impacted third molar tooth without obvious clinical and radiographic features. Patients advised for prophylactic removal of third molars as per orthodontic needs (before treatment, after treatment and during the course of orthodontic treatment) with an age range between 14 and 25 years were considered for the study. Patients complaining of any clinical symptoms and obvious radiographic features associated with impacted third molars were excluded. After obtaining an informed written consent, a detailed case history of each subject was recorded.

Orthopantomographs were taken for all the subjects. The contours of the tooth and of the pericoronal space were traced on tracing paper using the X-ray viewer. The widest point of the follicular space was measured using a graduated scale. Subjects who had follicular space >2.5 mm were excluded from the study.

The surgical procedure was carried out at the Department of Oral Surgery under local anesthesia following standard guidelines for surgical procedures. After the tooth was removed, the follicle was carefully enucleated from the socket attachment and was obtained for histopathological evaluation.

The removed specimen was immediately washed and spread on the Watman's number one filter paper to make it flat and the paper was folded without folding the specimen. The specimen was fixed in 10% neutral buffered formalin, processed and 5-μm-thick sections were prepared from paraffin blocks and stained with hematoxylin and eosin stains. Three trained oral pathologists reviewed the stained microslides. Wherever there was disagreement, the slides were discussed and a common consensus was obtained.

The features evaluated by the oral pathologists were (1) presence of epithelial tissue, (2) type of epithelial tissue: (a) reduced enamel epithelium (REE) and (b) stratified squamous epithelium (SSE), (3) presence of inflammation and (4) other features like calcification, giant cells, ghost cells.

Observations were tabulated and percentage was obtained. Associations between the attributes were tested using chi square with Yate's correction.


Forty-one dental follicles were assessed for histological examination from 30 subjects. Thirty-nine follicles were from mandibular 3 rd molars and two follicles were from maxillary 3 rd molars. The age of the subjects ranged from 14 to 25 years. Twenty subjects were female and 10 were male.

Of the 41 follicles evaluated, 15 showed REE (36.5%) [Figure 1], 21 showed SSE (51.2%), absence of epithelium was seen in five follicles (12.19%) [Table 1], 21 dental follicles showed cystic changes out of which 18 follicles showed features of dentigerous cyst [Figure 2], two showed odontogenic keratocyst (OKC) [Figure 3], one follicle showed calcifying epithelial odontogenic cyst (CEOC) changes. One follicle each of odontogenic fibroma, myxoma and ameloblastoma-like proliferation [Figure 4] were observed [Table 1] and [Table 2]. Ten follicles showed presence of inflammatory component within the stroma [Table 3] and 13 (31.7%) showed dystrophic calcification. Proliferating odontogenic epithelial islands were seen in the stroma of six (14.6%) follicles [Figure 2].{Table 1}{Table 2}{Table 3}{Figure 1}{Figure 2}{Figure 3}{Figure 4}


The incidence of impacted or embedded teeth accounts for 14-96% of the population, of which 98% of the impacted teeth are third molars. Only 50% of third molars erupt into the oral cavity. The most common reason for failure in eruption is decreased size of the jaw, which results in lack of space for eruption. [8] Since 1949, both histologic and radiographic studies on dental follicles have reported early pathological changes. Similar study by Sutas Rakprasitkul in 2001 on asymptomatic dental follicle reported presence of dentigerous cyst, OKC and ameloblastoma. [4]

The present study was carried out to analyze early pathologic changes associated with asymptomatic dental follicle of the impacted third molar. The study group comprised 41 follicles with radiolucency up to 2.5 mm because most of the studies suggested that pericoronal radiolucency more than 2.5 mm is pathologic. [7],[9] Radiographic examination is important in identification of an enlarged pericoronal space that is suggestive of pathologic process. The critical width of the follicle as seen radiographically has been estimated to be between 2 and 5 mm. [10] Shear suggests that some unerupted teeth have a slightly dilated follicle in the pre-eruptive phase. This does not signify a cyst or even necessarily a potential cyst unless the pericoronal width is at least 3-4 mm. [11] Campbell and Glosser suggested pericoronal radiolucency of 2.5 mm or more as evidence of radiographic pathology. [12] Radiographic interpretation of a pericoronal space as normal or pathologic is difficult. Thus, several researchers have concluded that radiographs alone are insufficient to diagnose pathological changes, making histological diagnosis necessary. [13]

In the present study, three different oral pathologists analyzed the hematoxylin and eosin section of dental follicles independently. The presence of lining epithelium was noted in 87.8% of the follicles. Of this, reduced enamel epithelium was present in 36.5% (out of 41 follicles) of the follicles and absence of epithelium was found in 12.19% [Table 1]. This is in consistence with studies reported by Damante and Fleury. They concluded that the loss of epithelium may have resulted from the ameloblast cell adherence to the enamel cuticle, which detaches from parts of the specimen during surgical treatment. [13] Using noted that the reduced enamel epithelium was more firmly attached to the enamel surface of the tooth rather than to the dental follicular tissue, because of which it has a tendency to become discontinuous or absent. [3]

In the present study, 51.2% (21 follicles out of 41) of the follicles showed a cyst-like change lined with the stratified squamous epithelium [Table 1], of which two showed OKC, one showed CEOC and 18 showed dentigerous cyst-like appearance, one each of ameloblastoma-like proliferation, odontogenic fibroma and myxoma were also noted (2.4%) [Table 2]. Rukprasitkul Sutas, in his study on asymptomatic pericoronal tissue of impacted third molars, found 58.65% of dentigerous cyst changes, two cases of OKC and one case of ameloblastoma-like proliferation. [4] A similar study by Ali Hossein reported the presence of dentigerous cyst in 38% of the cases, ameloblastoma in 5.8%, followed by sulfur granules (4%), foreign body graulomas and stratified squamous epithelium (3%). [14] Similarly, Curran et al. studied histologic changes in the nonpathologic follicular tissue and diagnosed 32.9% pathologically significant lesions. Dentigerous cyst (77.5%) had the highest incidence followed by OKC (9.1%), odontoma (8.2%), ameloblastoma (1.5%), CEOC (0.7%), carcinoma (0.7%) and myxoma (0.1%) cases. [15] Glosser and Campbell found pathological changes in 32% of the impacted 3 rd molar follicles, [12] Aldelsperger et al. detected pathosis in 34% [9] and Baykul et al. have described cystic changes in 50% of asymptomatic follicles. [1] These findings are in accordance with the present findings.

In the present study, odontogenic fibroma was noted in one follicle (2.4%). Histologic features of the simple type of odontogenic fibroma are often not much different from those of dental follicles. Differentiation of odontogenic fibroma from dental follicle often requires clinical and radiographic evaluation as well as histologic observation. [3] Myxoma-like change was seen in one specimen (2.4%). Conklin observed such myxomatous type of connective tissue in 36% of the cases and observed that this type of tissue resembles embryonic mucoid tissue, which may arise at any place in the mature body where loose connective tissue is stimulated to neoplastic proliferation. [16]

In the present study, proliferating epithelial islands were seen in 14.6% of the follicles. Whereas in a study conducted by Conklin, 86% of the follicles showed epithelial islands. [16] The presence of inactive rests of odontogenic epithelial islands is a frequent finding in the follicles of normally developing teeth. Proliferation of such epithelial rests may indicate neoplastic change. Lukinmaa suggested that the frequency and number of odontogenic epithelial rests appear to decrease with increase in the age of patients. [17] Foci of calcifications are seen as a normal finding in the dental follicles. The present study showed 13.7% of follicles with foci of dystrophic calcification. Jim Kin and Gary. L. Ellis found 37% of follicles with dystrophic calcification whereas Stanley and co-workers found approximately one-third of the unerupted follicles with dystrophic calcification. [18],[3]

On correlating the histopathologic evaluation with clinical data, it was found that the pathological changes in the follicles were more in male (nine out of 10 males) as compared to female (14 out of 20 females). A statistically significant correlation was found in association with dentigerous cyst and gender (90% of all males and 47.6% of all females, with P-value <0.05 ) [Table 4]. The age group ranged from 14 to 25 years. Young adults were considered for study, because studies have shown that as age increases there will be an increase in pathologic changes. [9] These findings were found to be in consistent with the study conducted by Ali Hossein on asymptomatic impacted 3 rd molars. [14]{Table 4}

The present study showed significant changes of dentigerous cyst in the apparently normal follicle in age ranging from 14 to 25 years. Shear and Bernick have reported the peak incidence of dentigerous cyst in the second decade. [11],[19] Mourshed found a 1.44% incidence of dentigerous cysts in a radiographic examination of unerupted teeth. Knight's et al., in a microscopic study, found dentigerous cysts in 44.70% of the impacted teeth. Consolaro showed that with aging there is a tendency of transformation of reduced enamel epithelium into stratified squamous epithelium. [13] Similarly, David Moraes de Oliveria et al., in their study, compared the stage of rhizogenesis (Nolla's classification) with the type of epithelium. They found 28.1% incidence of presence of stratified squamous epithelium in stage 9 thus suggesting that the transformation of reduced enamel epithelium into stratified squamous epithelium with maturation of the follicle and consequently with increasing age. [20]

The present study showed presence of stratified squamous epithelium in the age group of 14-28 years. This metaplastic change could be indicative of early pathological changes. [11],[13] Glosser and Cambell and Curran et al. argue that any follicle with stratified squamous epithelium should be regarded as a dentigerous cyst. [12],[15] Aldesperger et al. demonstrated an association between squamous differentiation and proliferative activity of the epithelium using proliferating cell nuclear antigen. The authors disagree with the view that squamous metaplasia is a normal change that takes place during the maturation of the follicle, and stated that it represents an early pathosis. [9] However, Daley and Wysochi and Olivera contradict, suggested that the presence of stratified squamous epithelium cannot be diagnosed as a dentigerous cyst but rather as follicular tissue with squamous differentiation. [10],[20]

The radiographic width of the follicles ranged from 1 to 2.5 mm. 58.5% of the follicles with pathological changes had follicular space ranging from 2 to 2.5 mm [Table 5] and [Table 6].This was in consistence with studies by Glosser and Campbell, who noted 37% of follicles showing dentigerous cyst in asymptomatic impacted third molars with a pericoronal space width of 2.4 mm. [19] Adelsperger noted 34% of follicles showing cystic change with <2 mm pericoronal follicular space. [9]{Table 5}{Table 6}

Theoretically, inflammation should not be expected in follicles of asymptomatic impacted teeth, but it was observed in some cases in the present study. 38.9% of follicles with stratified squamous epithelium were associated with inflammation [Table 3] as compared to 13.3% of cases with reduced enamel epithelium. Damante and Fleury found 36.1% of follicles showing inflammation. Inflammatory infiltrate in the follicles could be physiological, for example during tooth eruption where the erupting process occurs with an inflammatory reaction originating from the penetration of oral antigens because of the wider intercellular spaces of the epithelial cells of reduced enamel epithelium than oral epithelium and that many unerupted teeth may communicate with the oral environment through the periodontal pocket of an adjacent tooth. [13] Oliveria, in his study, correlated inflammation in the connective tissue to stage of rhizogenesis and concluded that inflammation increased with the progression of the rhizogenesis, which may be due to the physiology of eruption or proximity to the oral environment. [20]

The present study has shown that 58.5% of the follicles were associated with pathological changes, suggesting removal of asymptomatic impacted third molars at an early age. To substantiate this are reports by Daley et al. and Shear, who stated that the incidence of impacted teeth undergoing dentigerous cyst transformation is 0.1-0.6% and 1.5%, respectively. [11],[21] These lesions can be found most commonly in the 2 nd and 3 rd decade of life. [11] Furthermore, Leitner et al. reported the first case of low-grade fibrosarcoma in a 23-year-old female associated with impacted 3 rd molar without any clinical evidence of a follicular lesion. [22]

Stanley et al. reviewed the pathology associated with third molars in an average age group of 47 years and an average retention period of approximately 27 years. They found dentigerous cystic changes in 30 impacted third molars. Some type of pathologic changes can be expected eventually in approximately 12.0% of the impacted third molar population and 1.82% of the general population. [18]

Tokvo et al., in their study on impacted third molars in elderly persons, found 26 cases of pericoronitis, eight infected dentigerous cysts, four abscesses, two osteomyelitis and one case of odontogenic skin fistula. Thus, they suggest that long-term retained third molars in elderly persons are associated with infection, which results in surgical removal complications. [23]

Aging complicates all aspects of surgery and recovery. Moreover, pathologic processes in older persons have more time to enlarge and also require more extensive surgery. Development of large cystic lesions in the mandible reduces the bulk of the bone and reduces in size. Healing is often delayed as age increases. [24] All the above-mentioned data suggests for early removal of third molars even when they are asymptomatic. The present study showed a higher incidence of pathologic change in radiographically normal appearing follicle. This also suggests that the absence of the radiographic feature is not necessarily reflective of the absence of disease. Hence, the clinician, while treating any asymptomatic impacted third molar teeth, should perform a detailed clinical and radiographic examination and, after surgical removal, submit the dental follicular specimen for histological evaluation so as to understand the biologic changes associated with impacted teeth and to decrease the morbidity related to impacted teeth.

Future scope of the study is to include more number of dental follicles and use three-dimensional computerized tomography scan to measure the accurate width of the follicle and compare with histologic findings so that a definite protocol can be obtained for removal of asymptomatic impacted third molars.


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