The buccal bifurcation cyst (BBC) is an uncommon lesion associated with the permanent
    mandibular first or second molar in children. Usually it is identified just prior to
    eruption. Stoneman and Worth in 1983 were the first to describe the lesion and report its
    radiographic and clinical features.1 They named the lesion mandibular infected
    buccal cyst. Similar lesions have been described in the literature under a variety of
    names. They include the circumferential dentigerous cyst,2 the inflammatory
    paradental cyst,3 and the inflammatory collateral dental cyst.4 The World
    Health Organization5 describes this lesion under the name "paradental
    cyst." Neville, Damm and Allen et al. state that this latter name should be avoided
    because it is non-specific.6 Pompura, Sāndor and Stoneman7 argue
    for the term BBC, because the lesion is site- and age- specific. It has a constant
    relationship to the mandibular first molar's buccal bifurcation (Table I).
    
      
        |  Table II | 
      
      
        | Radiographic Features of the Buccal Bifurcation
        Cyst | 
      
      
        | 
         | 
      
    
    The histology of this lesion is non-specific and reveals non-keratinized
    stratified squamous epithelium, areas of epithelial hyperplasia and an inflammatory
    infiltrate in the connective tissue wall. Bacteriology reports have shown a mixed flora.7-9
    The differential diagnosis of this lesion includes eosinophilic granuloma, lateral
    periodontal cyst, traumatic bone cyst and periostitis ossificans. Usually, the clinical
    and radiographic features distinguish the BBC from other conditions.8
    Treatment of the BBC has evolved over time. The low incidence of this lesion makes
    randomized controlled trials impractical. Stoneman and Worth report successful treatment
    through tooth extraction and curettage of the lesion, as well as with endodontic treatment
    of the tooth and curettage of the lesion.1 Enucleation and extraction are reported by
    Trask, Sheller and Morton10 and more recently by Martinez-Conde, Aguirre and Pindborg.11
    Stanback reports treatment via marsupialization.12 Enucleation alone is
    reported by several authors.8,9,13,14 Pompura, Sāndor and Stoneman7 recently
    report the successful treatment of 44 BBCs with enucleation alone (without tooth
    extraction). The following cases illustrate an even more conservative approach to
    treatment.
    
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    Cases 
    Case 1
    During an orthodontic consultation, an 8-year-old male was noted to have bilateral
    cystic lesions of the mandible. He was asymptomatic, but on intraoral examination buccal
    tilting of the associated teeth and deep buccal periodontal pockets were noted. Mild
    bilateral swelling was noted extraorally. The lesions were pointed out to the patient and
    his mother, who were advised to see an oral and maxillofacial surgeon for management.
    The family moved away for a year and never sought treatment. At a follow-up visit 15
    months later, the lesions showed definite signs of radiographic resolution. Six months
    after this initial follow-up, there was no clinical or radiographic evidence of the cysts
    at all (Figs. 2a-2f).
    Case 2
    A 9-year-old male had BBCs associated with teeth 3.6 and 4.6. These teeth were tilted
    buccally and were associated with deep buccal periodontal pockets. No treatment was
    rendered. During nine months of follow-up, the cyst adjacent to tooth 4.6 enlarged and
    required surgical treatment, and the cyst adjacent to tooth 3.6 regressed without
    treatment (Figs. 3a-3d).
    Case 3
    A 7-year-old male was treated by his physician with a course of amoxicillin for pain
    and swelling of the mandible and was subsequently referred to his dentist. On examination,
    the patient had swelling and tenderness in the region of the right angle of the mandible.
    Intraorally, the soft tissues buccal to teeth 3.6 and 4.6 were inflamed and slightly
    erythematous. Periodontal probing revealed depths of 11 mm to 12 mm bucally. Both crowns
    were tilted buccally. The pockets were irrigated with saline and hydrogen peroxide and the
    patient was instructed to irrigate these areas at home daily with saline rinses. The
    patient was reassessed weekly. Over several months, the defects resolved with irrigation
    and the periodontal status returned to normal. The probing depths were 2 mm to 3 mm
    buccally, and the patient's pain, swelling and inflammation ceased (Figs.
    4a-4d).
    
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    Discussion 
    The etiology of the BBC remains uncertain. Different theories have been proposed.
    During eruption, as the cusps penetrate the oral epithelium, a localized area of
    inflammation may occur beneath the epithelial attachment. The fact that the mesiobuccal
    cusp of the first molar is the first to break through the epithelium might explain the
    development of the lesion on the buccal surface at about the time of eruption.1
    The cystic epithelium may be derived from the cell rests of Serres, the cell rests of
    Malassez, apical migration of cells of the dental lamina or reduced enamel epithelium.7 As
    Camarda, Pham and Forest8 state, however, this explanation does not account for the reason
    these lesions have not been seen with erupting incisors. Another hypothesis is simply that
    this cyst is a variant of the lateral periodontal cyst.1 This lesion is also
    site-specific, namely to the canine and premolar region, and rarely occurs in children.7
    Enamel projections into the buccal bifurcation may also be a causative factor.
    Pompura, Sāndor and Stoneman point out that these lesions are not seen in adults and
    questioned whether they may be self-limiting.7 Evidence from these three
    patients with five cysts indicates that some of these lesions are self-limiting. The
    authors speculate that perhaps microtrauma and subsequent inflammation of the buccal
    gingival tissues and the cyst lining may induce a small opening into the lesion. This
    "automarsupialization" may allow the cyst to depressurize and heal
    spontaneously. Periodontal probing may also result in "micromarsupialization."
    Case 2 illustrates simultaneous regression of a lesion on one side and continued growth of
    a BBC on the contralateral side. Factors that predict which lesions may be more
    susceptible to spontaneous resolution are unknown. Although there are no guidelines on
    which cysts need to be watched and which require surgical treatment, the authors emphasize
    that at least some BBCs may not require surgery. Consideration should therefore be given
    to managing BBC cases conservatively with an expectant "watchful inactivity."
    Clinical and radiographic re-evaluation should occur at three- to six-month intervals.
    Infected lesions or those increasing in size must be managed surgically. 
    
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    Acknowledgment: the authors thank Dr. M. Dagenais for her
    radiographic contribution to this paper.
    Dr. David is resident, Oral and Maxillofacial Surgery,
    University of Toronto.
    Dr. Sāndor is coordinator of Oral and Maxillofacial Surgery,
    Hospital for Sick Children and Bloorview MacMillan Centre; director, graduate residency
    program in Oral and Maxillofacial Surgery, The Toronto Hospital; and assistant professor,
    University of Toronto.
    Dr. Stoneman is professor emeritus, Department of Radiology,
    Faculty of Dentistry, University of Toronto; and consultant oral radiologist, Hospital for
    Sick Children and The Toronto Hospital.
    Reprint requests to: Dr. G.K.B. Sāndor, Hospital for Sick
    Children, 555 University Ave., Toronto, ON M5G 1X8.
    
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    Click to see the larger image 
    Fig. 1: Occlusal radiograph of a buccal
    bifurcation cyst showing lingual displacement of the first molar roots and the resultant
    increased prominence of the lingual cusps. Note also the thinning of the buccal cortex and
    periosteal reaction.
    
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    Click to see the larger image 
    Fig. 2a: Large buccal bifurcation cyst around
    tooth 4.6.
    
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    Fig. 2b: Bone fill noted at 15 months without
    treatment.
    
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    Fig. 2c: Complete resolution of cyst with
    uprighting of tooth 4.6 at 21 months.
    
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    Fig. 2d: Lesion around tooth 3.6.
    
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    Fig. 2e: Bone fill at 15 months without treatment.
    
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    Fig. 2f: Complete resolution of cyst
    
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    Fig. 3a: Lesion around tooth 4.6 with faint radiopaque
    concave line at apices and prominent lingual cusps.
    
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    Fig. 3b: Spontaneous enlargement of lesion 9 months
    later.
    
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    Fig. 3c: Lesion around tooth 3.6 with faint radiopaque
    lines at apices and prominent lingual cusps.
    
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    Fig. 3d: Spontaneous bone fill around apices and mesial
    and distal of tooth 3.6 at 9 months without treatment.
    
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    Fig. 4a: Faint radiopaque line at apices and distally
    around tooth 3.6.
    
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    Fig. 4b: Resolution of cyst at tooth 3.6.
    
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    Fig. 4c:Smaller cyst at tooth 4.6; faint radiopaque
    line at mid apices
    
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    Fig. 4d: Spontaneous healing of cyst at tooth 4.6..
    .