Implant Placement After Marsupialization of a Dentigerous Cyst

Implant placement, after enucleation of jaw cysts and bone grafting, is an acceptable and well-documented procedure in clinical practice.1–4 There are cases, however, where cyst enucleation may present a potential risk of damaging sensitive anatomic structures such as the mandibular nerve canal. On the other hand, graft procedures—especially when a large defect is to be filled—are a concern for a number of patients. Although marsupialization is a reliable alternative in these cases, to our knowledge there is a lack of references to implant placement after bone regeneration via marsupialization. This paper presents a case of single implant placement after marsupialization in the mandible and discusses the advantages and disadvantages of this treatment option.

An 18-year-old female patient presented to the clinic with a history of pain and swelling in the left mandible. At that time, clinical examination revealed nothing out of the ordinary. The panoramic examination, however, revealed a large, ovoid, and well-defined radiolucency, extending from the third left mandibular molar up to the first premolar and containing the second molar. The roots of the first molar presented partial resorption, while the lower borders of the lesion were in close proximity to the roof of the mandibular canal. The apices of both premolars were within the lesion and the pulp vitality test was negative for both. The initial diagnosis was dentigerous cyst (Figure 1). The plan was the endodontic treatment of the premolars, extraction of the first molar, marsupialization of the cyst, and orthodontic movement of the second molar.

The removal of the cyst wall was performed through the postextraction socket of the first molar. In order to facilitate the second molar's erupting, the incision and bone removal were extended distally (Figures 2 and 3). Intra-operatively however, resorption of the lingual aspect of the distal root of the second molar was noted. Extraction of the second molar was then preferable to moving it orthodontically. The extraction was performed 3 months later because of the close proximity of its apices to the mandibular canal. The biopsy of the cyst wall revealed absence of keratinized epithelium and therefore confirmed the initial diagnosis.

Twelve months after marsupialization almost total disappearance of the radiolucency was noted. Moreover, the radiograph showed that a sufficient amount of bone was deposited over the roof of the mandibular canal (Figure 4). A very satisfactory clinical result was observed; the defect was flattened and totally covered by oral mucosa (Figure 5). In addition, no hyperplastic tissues or fistulas were observed. An implant of 15 × 4 mm (ICE, 3i Implant Innovation Inc, Palm Beach, Fla) was inserted in the region of first left mandibular molar (Figure 6). The bone formation on the buccal and lingual aspect of the defect was very satisfactory and resulted in excellent primer stability of the implant. However a thin central zone of the defect remained devoid of bone. After intensive excision of all soft tissues, an alloplastic bone substitute was placed (Biogran, Orthovita, Malvern, Pa). Eight months later (20 months postsurgery), the implant was uncovered and the restorative procedure (customized University of California at Los Angeles abutment and cement-fixed metal-ceramic crown) followed. The implant and the crown have been functioning for 48 months postinsertion, with no clinical, radiographic signs or symptoms observed or reported by the patient (Figures 7 and 8).

After considering procedural advantages, marsupialization instead of enucleation was performed in this case for the following reasons.

There was no possibility of damaging the nerve canal. Although asymptomatic dentigerous cysts do not usually involve the mandibular canal and subsequently are easily separated from surrounding tissues and removed, this might not be expected in cases with a history of inflammation. The possible existence of adhesions may have complicated the procedure and made it less predictable. Beside these anatomic and surgical concerns, enucleation would have resulted in the creation of a large defect. The size of the latter would have necessitated grafting procedures in order to be filled, partially by autologous bone, making the operation more invasive and complex. Further, the patient was not anxious to undergo a second operation. In addition there are still controversies with respect to the ability of osseoconductive graft materials, when used alone, to generate vital bone comparable to the preexisting one and to mimic the natural mechanical properties. Tadjoedin et al5 and Cordioli et al 6 reported satisfactory bone regeneration patterns when bioactive glass was used as bone substitute in sinus lift procedures, but only in combination with autologous bone. Carmagnola et al7 reported that although they confirmed new bone formation after grafting defects with osseoconductive bone xenograft, histological examinations revealed absence of bone-implant contact. On the other hand, Valentini et al8 stated that both osteogenesis and bone-implant contact were satisfactory after placement of osseoconductive bone xenografts. It is worthy of mentioning that the long-term good prognoses of dental implants are related to their placement in preexisting natural bone.9,10 To our knowledge, positive long-term results, fully comparable to the previous ones of implant survival rates, currently are not available for insertion in newly generated bone.

Enucleation, unlike marsupialization, would have necessitated apicectomy of both premolars in order to gain good access and completely remove the cyst. This would have made the surgery more invasive. Alternatively we performed conventional endodontic treatment. It is a matter of concern, however, that although dentigerous cysts do not usually prevent blood supply to the pulp of the adjacent teeth due to their slow development, the premolars were nonvital (confirmed by the vitality test). It is speculated that the history of inflammation of this area may have influenced the pulp vitality of these teeth.

Additional reasons for marsupialization rather than enucleation were that the potential risk of postoperative inflammation would have been greater after enucleation and bone grafting in a large defect like this; the quantity of alloplastic graft material needed was very small; and the extraction of the second molar was easier due to its movement coronally.

It is unclear to us why this tooth presented with root resorption. A possible explanation might be that the cyst formation process preceded that of amelogenesis, and this in part influenced the completion of the latter.

The disadvantages of the chosen treatment plan were the long healing period and the relative discomfort of the patient, especially during the initial phase of marsupialization (due to the use of the stent). It was estimated, however, that the advantages mentioned above outweighed the disadvantages in this case.

It is believed that a more conservative surgical management of jaw cysts in a young population might be preferable because of the rapid developmental changes in this area. This approach is consistent with the findings of Bonder11 and Jones et al.12 The panoramic images in our case revealed sufficient bone apposition over the roof of the mandibular canal. This is consistent with the findings of Bonder et al13 who used more advanced imaging modalities, such as CT with multiplanar reconstruction. They also observed postmarsupialization remodeling of the cortex of the mandibular canal and the increased distance between the cyst's wall and adjacent structures.

Implant insertion after marsupialization of a cyst defect, in combination with placement of a small quantity of an osseoconductive bone substitute, may present an advantageous alternative solution over enucleation, when anatomic limitations are a concern, and autograft procedures, especially in a young population, are not acceptable as a treatment option. However, this paper is a case report and more scientific data in this field are necessary.

The information presented here was reported at the 23rd Pan-Hellenic Dental Congress, Athens, 2003. The authors claim to have no financial interest in any company or product mentioned in this article.