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The Seven-year Journey of an Ectopic Canine: Multidisciplinary Management of a Dentigerous Cyst in the Early Mixed Dentition Thibault Colloc Roderick Morrison Mark Burrell Colin Larmour Dental Update 2024 48:10, 707-709.
Authors
ThibaultColloc
DDS, MFDS RCPS(Glasg)
Post Dental Core Trainee Fellow, OMFS Department, Ninewells Hospital, Dundee
The Aberdeen Royal Infirmary oral and maxillofacial surgery department is involved in the joint planning of cases with the orthodontic and restorative departments of the Aberdeen Dental Hospital to agree an optimal treatment plan for patients, with input from all three specialties. A 7-year-old girl was referred to the orthodontic department by her GDP due to non-eruption of the upper left central incisor. This was related to an associated dentigerous cyst. This presentation illustrates the phases of treatment involving marsupialization of the dentigerous cyst; surgical extraction and orthodontic treatment in order to provide the patient with the optimal outcome for her dentition. A retrospective assessment of the case is presented through photographs and radiological imaging outlining the chronology of the treatment and the outcome of marsupialization of the dentigerous cyst. It highlights this more conservative surgical approach as giving the best chances of preserving unerupted teeth in a younger patient. Marsupialization of a dentigerous cyst associated with UL1 and conservative management of cystic pathology led to preservation and natural mesial eruption of UL3 into the position of UL1. The unerupted UL1 associated with cystic pathology was extracted due to its ectopic position and root dilaceration. Seven years after diagnosis of the dentigerous cyst associated with the unerupted UL1, surgical and orthodontic management has facilitated the for patients tooth to erupt into the UL1 position. Restorative treatment is being planned following orthodontic treatment to restore for patients tooth to simulate the missing UL1.
CPD/Clinical Relevance: This case encourages the appropriate referral of young patients with dentigerous cysts to achieve a satisfactory outcome.
Article
A dentigerous cyst is one that encloses the crown of an unerupted tooth by expansion of its follicle.1 It is the most prevalent type of developmental odontogenic cyst with about 1.44 cases in every 100 unerupted teeth2 comprising almost 20% of all odontogenic cysts and 60% of developmental odontogenic cysts.3 In the paediatric population, they account for 30% of the total number.4 It is most frequently encountered in association with impacted third molar teeth in the lower jaw, their distribution is directly compared to the frequency of impacted teeth. These cysts develop most commonly around the crown of an unerupted impacted tooth and attach to it at the cemento-enamel junction.5
On imaging, dentigerous cysts are usually present as a well-defined and unilocular radiolucency surrounding the crown of an unerupted or impacted tooth. They have a thin, regular sclerotic margin and can expand the overlying cortical plate. They are sometimes identified on orthopantomographic imaging as an incidental finding. An expanding peri-coronal lesion containing the crown of an impacted tooth projecting into the cystic cavity is considered pathognomonic and often, no further imaging is indicated unless there are other features, such as displacement of adjacent teeth and/or evidence of other pathology, for example resorption.6
Enucleation is the modality of treatment that involves complete removal of the cystic lining and extraction of the associated tooth, although this option is not always straightforward owing to the location and size of the cyst. Marsupialization is a conservative approach and is indicated when managing very large cysts when complete removal of the cystic lining would be difficult, and also when attempting to preserve and facilitate eruption of involved teeth.7 It is a particularly useful technique for the management of odontogenic cysts in paediatric patients when an important objective is to facilitate the eruption of developing teeth.
The marsupialization technique involves creating a surgical cavity on the wall of the cyst and emptying its content and subsequently maintaining the continuity between the cyst and the oral cavity by suturing the cystic lining to the oral mucosa. Close follow up is necessary in the post-operative period to ensure patency of the cyst cavity with the use of packs and careful patient irrigation. It is generally contraindicated for infected lesions unless the source of the infection, such as a non-vital tooth is managed concurrently.8
Following marsupialization and decompression of the cyst, subsequent bony healing and dental development will often facilitate spontaneous eruption of unerupted teeth. Eruption is not always successful and for some patients, subsequent surgical exposure and orthodontic alignment may be required. If successful, this will facilitate cyst resolution along with preservation and alignment of the unerupted tooth. It is generally agreed that there is a close relationship between the ability of a tooth to erupt and the stage of dental root formation. A permanent tooth erupts through the alveolar bone when approximately two-thirds of the root has formed and emerges into the oral cavity at approximately three-quarters to complete root formation with a wide-open apex.9 Therefore, the younger paediatric group of patients will have a greater potential for successful eruption following cyst marsupialization compared with older patients for whom root development is complete. This is supported in the literature with case reports such as Hu et al10 who reported successful management of an odontogenic cyst, including subsequent tooth eruption with marsupialization.
Marsupialization is, unfortunately, not always successful and the literature reports cases where the dentigerous cyst was marsupialized in the first instance but subsequently required enucleation along with removal of the associated tooth. Aoki et al describe a case where, following marsupialization of a dentigerous cyst involving a deeply impacted UR3, the tooth failed to erupt despite surgical exposure and orthodontic traction. Thanks to multidisciplinary management, the marsupialization allowed bone regeneration in the cystic area and despite loss of the UR3, this bone formation allowed the placement of a dental implant to restore function and aesthetic appearance for the young patient.11 Failure of eruption can be influenced by many factors, such as age of the patient, tooth depth, tooth inclination, stage of root formation (open or closed apex) and the amount of space available.12,13 By contrast, other authors reported that these factors are not significant and do not effect tooth eruption.14
Case report
A 7-year-old girl was referred to the hospital orthodontic service by her GDP due to non-eruption of the upper left central incisor and displaced position of the erupted upper left lateral incisor. She was fit and well with no other complicating medical problems. She was a regular dental attender with no history of trauma or other injuries. There was no family history of dental eruption problems.
The patient presented with a mild Class III malocclusion with an anterior open bite tendency exacerbated by a thumb-sucking habit, and was in the mixed dentition. On assessment her main concern was delayed eruption of the upper left central incisor (UL1).
Clinical examination revealed an unerupted UL1 with retained deciduous teeth ULA and ULB. A firm buccal bulge was noted overlying these teeth. The upper left lateral incisor had erupted in a marked ectopic position distal to the ULB (Figure 1). An initial radiograph confirmed probable cystic pathology related to the UL1, with associated follicular expansion and significant distal displacement of the upper left permanent canine, which was in an ectopic position being apical to the UL6 and developing UL7 (Figure 2). The panoramic radiograph showed a large radiolucent lesion measuring 14 x 15 mm associated with UL1, which was in an ectopic position being high and horizontal. Otherwise, all permanent teeth were present apart from the developing third permanent molar teeth.
Figure 1.
(a, b) Initial clinical assessment shows non eruption of UL1 and retained ULA and ULB along with ectopic position of UL2.Figure 2.
(a, b) Initial radiographic assessment confirms ectopic position of UL1 and marked distal positioning of UL3, with evidence of circumscribed radiolucency related to UL1 extending distally to UL3.
Following this assessment, the patient was referred to the combined speciality clinic for further assessment by both orthodontic and oral and maxillofacial clinicians to consider management options. Following assessment, the following plan was agreed with the patient:
Surgery to marsupialize the dentigerous cyst;
To monitor bony healing and dental development, particularly in relation to the eruption of UL1 and UL3. In view of their ectopic positions, the patient was advised that there was a guarded prognosis for successful eruption.
The patient was subsequently admitted to the oral and maxillofacial department for surgical removal of ULA and ULB, biopsy of cyst UL1/UL2 region and marsupialization of the cyst (Figure 3) The procedure was carried out without complications. The patient was followed up closely in the immediate post-operative period with a Whitehead's varnish pack being used initially and removed under general anaesthetic 2 weeks after the initial procedure. Careful instructions for the patient and parents were given about wound care, including cleaning of the wound with distilled water using a syringe after each meal.
Figure 3. Radiographic assessment after marsupialization of cyst. It was taken 6 months post-operatively and confirmed good bony healing and favourable mesial movement of the UL3 with little change in position of UL1.
At the 3-week post-operative review the wound had healed well, and the cavity was noted to be patent and free from debris. The patient reported no problems or significant discomfort. The pathology of the biopsy was reported as benign squamous epithelial cells consistent with the diagnosis of a dentigerous cyst. Six months post-operatively, a minor favourable change in the vertical position of the UL1 was noted radiographically, although it remained in a high horizontal position. Radiographically, UL3 showed signs of favourable mesial migration following marsupialization and was noted to be transposing in position with the UL2. CT imaging was organized to allow more detailed assessment of UL1 and to assess bony healing. The imaging confirmed root dilacerations of the UL1 and a ‘fuzzy’ root appearance in the apical third which was suggestive of external resorption (Figure 4).
Figure 4. CBCT confirming horizontal positioning of UL1 and root dilaceration and possible early resorption
Following discussion with the patient, a decision was made to surgically remove the UL1 due to its continued unfavourable ectopic position and root dilaceration and probable early resorption. Six-monthly reviews were organized to follow the progress of her dental development, including the eruption progress of UL3. Approximately 5 years after her initial surgical procedure, the UL3 was noted to have continued to erupt in a transposed in relation to UL2 (Figure 5). Following planning with surgical, restorative and orthodontic clinicians, a decision was made, after discussion with the patient, to surgically expose UL3 with a view to subsequent orthodontic traction to align this tooth in the position of the missing upper left central incisor and its probable restoration long-term to simulate the missing upper central incisor, depending on its appearance, following full eruption. This surgical procedure was successful, and 13 months into orthodontic treatment, the UL3 was in line of the arch in the position of UL1 (Figure 6). Careful management of the orthodontic alignment phase was required to avoid damaging the root of UL2 because the transposed UL3 was aligning, which was achieved by delaying any labial root movement of UL2 until the later stages of the alignment phase. The patient underwent the final phases of orthodontic treatment prior to the removal of her orthodontic appliances. The restorative team were happy with the canine crown form, size, shade and emergence profile, and restoration of UL3 to simulate the missing central incisor on removal of the appliances was planned with composite additions initially. They also planned to review the need for any reduction on the palatal aspect. The final restoration was delayed because of COVID-19.
Figure 5. Radiographic assessment prior to surgical exposure of UL3 confirms continued mesial movement and transposition of UL3.Figure 6.
(a, b) UL3 following exposure and orthodontic alignment in UL1 position with ongoing orthodontic treatment. Note bracket inversions on UL3 and UL2 helping with tooth root movements (UR3 root torqueing palatally and UL2 labially)
Discussion
In view of the patient's age, conservative management with marsupialization was the preferred option for management of this dentigerous cyst because it would give the best chance of preserving and encouraging spontaneous eruption of as many permanent teeth as possible. Complete enucleation is often the preferred treatment for dentigerous cyst management, but with such a young paediatric patient and the very large expanding nature of the cyst, it would have been much more invasive with more risk of damage to adjacent unerupted teeth. The marsupialization approach adopted in this case allowed resolution of the cystic cavity with subsequent bony healing and also allowed the preservation of adjacent displaced teeth, which subsequently erupted successfully. Physiologically, a younger patient's bone is more dynamic with a greater healing and regeneration capacity to allow resolution of areas of bony destruction through which teeth can subsequently erupt.15 Therefore, a conservative treatment approach, such as the marsupialization adopted in this case, should be considered to improve the potential for spontaneous eruption of affected teeth. Hyotomo et al16 showed 72% success for natural eruption of impacted teeth in a dentigerous cyst after marsupialization. Disadvantages of marsupialization include pathological tissue remaining in situ, possibly resulting in a more aggressive lesions occurring in the residual tissue, for example odontogenic keratocysts or ameloblastoma. This highlights the importance of the histological examination of a sample of the cyst following surgery.17 Another disadvantage of marsupialization is the longer post-operative duration of treatment, with the potential discomfort of leaving the wound open and the need for patient diligence with maintaining good oral hygiene with irrigation to maintain patency of the cavity created.18
Unfortunately, the upper left central incisor could not be preserved in this case owing to its very ectopic position and root dilaceration and possible early external root resorption, and this tooth was ultimately removed. At initial assessment the patient did not have 3D imaging, which may have allowed this to be identified, along with a more detailed assessment of the central incisor anatomy and positioning relative to the cyst and other structures. The multidisciplinary team now have a lower threshold for taking 3D images in such cases in view of the useful clinical information it can provide to better inform decision making and patient care at an early stage.
Conclusion
This case shows the importance of early detection of the abnormal sequence in dental eruption in the mixed dentition and highlights the necessity for early diagnosis and treatment for impacted teeth associated with a dentigerous cyst. Marsupialization can be a very effective treatment strategy for a dentigerous cyst in younger patients to preserve compromised teeth associated with the cyst. 3D imaging is recommended as a valuable diagnostic tool to optimize the patient's journey and treatment planning. The case report also highlights the importance of careful multidisciplinary planning with early orthodontic and restorative input to optimize treatment planning at the start and during the care of these patients, who will often have a long patient journey. Collaborative planning and working will optimize the care for these patients for a positive outcome restoring both function and aesthetics.
