Histopathology of furcation lesions associated with pulp degeneration in primary molars.

The purpose of this report is to describe the histopathology of radiolucent lesions associated with pulp necrosis in primary molars. Twenty-one carious, previously untreated, primary molars with radiolucent lesions were extracted with forceps under local anesthesia. If a lesion remained attached to the root, the specimen was transferred to 10% neutral buffered formalin. The sockets were gently curretted and the tissue transferred to formalin fixative. Specimens were processed, stained with hematoxylin and eosin and viewed under a light microscope. Most specimens contained a mixed response including granulomatous inflammation, chronic proliferative inflammation, acute inflammation, and epithelium. Granulomatous inflammation was the predominant response. The cellular population varied as to the relative amounts of lymphocytes, plasma cells, monocytes, macrophages, and polymorphonuclear leukocytes. Odontogenic epithelium was observed in 10 of the 21 specimens. Radiolucent lesions associated with nonvital primary molars may be classified as furcation granulomas, granulomas with epithelium suggesting potential for cystic transformation or furcation cysts. A radiolucent lesion in the root furcation is a classic radiographic sign of pulp necrosis in a primary molar (Winter 1962; Moss and Addelston 1965). In contrast, lesions associated with pulp necrosis in a permanent molar usually appear as a periapical radiolucency (Lalonde and Lueke 1968). These lesions may be diagnosed as either a granuloma or a cyst and histological examination is required to establish a final diagnosis.’ Granulomatous inflammation is a consistent feature of the periapical radiolucent lesions associated with permanent teeth (Weiner et al. 1982) and consists of a classical fasicular or swirling pattern of mononuclear series cells Block et al. 1976; Lalonde and Lueke 1968; Langeland et al. 1977; Weiner et al. 1982. surrounded by lymphocytes and fibroblasts (McKinney 1981). Compared to the extensive information describing periapical lesions in permanent teeth, limited information is available concerning the histopathology of lesions associated with pulp degeneration in primary teeth. Pulp pathology in primary teeth may cause pain and infection and adversely affect the developing successional tooth. Enamel hypoplasia, cessation of root development, positional alterations and arrested tooth development have been reported. 2 Knowledge of the histopathology of these lesions could provide additional insight for improving the treatment rationale. The purpose of this report is to describe the histopathology of radiolucent furcation lesions associated with pulp degeneration in primary molars. Materials and Method Specimens were obtained during extraction of 21 primary molars from 17 healthy children, eight females and nine males between four and 12 years of age. The extracted teeth included 10 maxillary first primary molars, four maxillary second primary molars, five mandibular first primary molars, and two mandibular secondary primary molars. All the teeth had carious pulp exposures and displayed a radiolucent lesion in the root furcation characteristic of pulp degeneration (Fig 1, page 280). In a few instances, the radiolucent lesion appeared to extend beyond the root furcation and encompass a portion of the remaining root structure. None of the teeth had received any previous pulp therapy although several teeth had been previously restored. None were considered suitable candidates for conservative pulp treatment. All the teeth were extracted in the usual manner with elevators and forceps under local anesthesia. When a lesion remained attached to the root structure after extraction, it was detached and transferred to 2 Binns and Escobar 1967; Brook and Winter 1975; Messer et al. 1980. PEDIATRIC DENTISTRY: DECEMBER 1987/VoL. 9 NO. 4 279 FIG 1. Mandibular first primary molar with radiolucent furcation lesion characteristic of pulp pathology. 10% neutral buffered formalin for fixation. All extraction sockets were gently curretted and the contents transferred to 10% formalin. The tissue specimens were processed for routine paraffin embedding and cut as 5 um serial sections. The sections were stained with hematoxylin and eosin (H&E) and examined under a light microscope to differentiate cell type and general features of the lesion.