Reconstruction of Ablative Defects Using Dental Implants

Benign and malignant conditions can result in the need for ablative surgery where segments of the tooth-bearing portions of the jaws require removal for adequate disease control. Aggressive cystlike lesions of the jaws may result in destruction of large areas of the alveolus and underlying structures, resulting in the loss of teeth. Tumors such as ossifying fibroma, aggressive fibromatosis, central giant cell granuloma, and ameloblastoma may lead to defects that are challenging to restore. This article examines the reconstruction of such ablative defects and those areas of deficient growth induced by radiotherapy in childhood to treat tumors such as rhabdomyosarcoma, retinoblastoma, or neuroblastoma.

Excision of benign and malignant orofacial lesions often extends into tooth bearing portions of the jaws in order to provide for adequate disease control. Aggressive cystlike lesions of the jaws may destroy large areas of the dentoalveolar process and underlying structures, resulting in the loss of teeth. Removal of tumors such as ossifying fibroma, aggressive fibromatosis, central giant cell granuloma, and ameloblastoma may create defects that are challenging to restore. This article examines the reconstruction of ablative defects and of regions of the jaws arrested in development by delivery of radiotherapy in childhood to treat tumors such as rhabdomyosarcoma, retinoblastoma, or neuroblastoma.

Odontogenic keratocysts

Odontogenic keratocysts can be aggressive, and their removal can lead to major dentoalveolar loss requiring future reconstruction. The management of odontogenic keratocysts is made more difficult because they tend to recur. The syndromic association of multiple odontogenic keratocysts with basal cell carcinomas is called basal cell nevus (Gorlin) syndrome. The gene responsible for this condition has been identified and is known as the sonic hedgehog gene. The management of both new and recurrent lesions in these patients is challenging. The risk of recurrences is elevated in adolescence and early adulthood so dental reconstruction should be postponed until growth has ceased ( Figs. 1 A– 1 I).

Fig. 1
( A ) Radiograph of maxillary alveolus in an 18-year-old male who had a large maxillary odontogenic keratocyst treated by enucleation and Carnoy’s solution. The maxillary left permanent lateral incisor and canine teeth are missing. ( B ) Two implants placed with labial dehiscences of bone. ( C ) A piece of bone wax is adapted to estimate the size of the ridge defect. ( D ) The estimated size of the ridge defect. ( E ) The suction trap in a blown apart view showing its various components. ( F ) When maxillary implants are being placed, bone can be harvested from the nearby zygomatic process. ( G ) The particulate bone graft harvested by the suction trap. ( H ) The particulate bone graft placed over the labial dehiscences. ( I ) Labial view of the restored implants with a small porcelain flange to correct for some vertical deficiency.

Other aggressive lesions such as the widespread recalcitrant pyogenic granulomas of the maxilla can also be challenging to manage and reconstruct ( Figs. 2 A– 2 H).

Fig. 2
( A ) Recalcitrant recurrent pyogenic granuloma-like lesions on both sides of the maxilla. The child presented at the age of 8 years with recurrent bleeding necessitating multiple soft tissue procedures and then extractions to gain control of lesions that caused chronic hemorrhage. ( B ) Panoramic radiograph taken at 11 years of age. ( C ) Panoramic radiograph at age 13 years after removal of further recurrences of the lesion and the permanent right and left incisors, right canine, and premolar teeth. ( D ) A total of five dental implants were placed at the age of 17 years to replace the missing maxillary teeth. Areas of bone deficiency were treated with particulate bone grafts harvested using the suction trap from the third molar extraction sites. ( E ) The prosthesis was fabricated to replace the missing teeth and alveolus. ( F ) Palatal view of the prosthesis after insertion. ( G ) Labial view of the inserted prosthesis. ( H ) Patient smiling with prosthesis in situ.

Fibro-osseous and giant cell lesions of the jaws

In children who are congenitally missing one or more teeth, treatment is usually postponed until after the cessation of skeletal growth in order to avoid disturbing normal dentoalveolar development. In contrast, in children with certain pathologies, the lesion must be removed irrespective of the stage of growth of the patient. If growth is incomplete at the time of surgery, then some disruption of normal development is inevitable either as a result of scarring or constraint caused by reconstruction hardware or because of failure of a free tissue transfer such as a fibula to grow. In cases such as these, where the ablative surgery itself is expected to impede or restrict growth of the jaws, and little or no further restriction would be expected to be superimposed by dental implants placed into the ablative defect, then a decision to proceed with the placement of implants may be made if there is sufficient functional and psychosocial justification to do so. Certain fibro-osseous lesions of the jaws may require resection during childhood. One such lesion is the ossifying fibroma. Large areas of the tooth-supporting alveolus may be lost when these lesions are resected ( Figs. 3 A– 3 D). Another such lesion is the giant cell granuloma when it cannot be successfully treated with serial steroid injections so that jaw resection is required to gain control of the lesion.

Fig. 3
( A ) Frontal view of an 8-year-old child following resection of an aggressive ossifying fibroma with ablative defect reconstructed with a vascularized fibular graft. ( B ) At the age of 8 years, a total of six dental implants were placed to replace the missing permanent teeth, a gap which extended from the right permanent canine to the left second permanent molar. ( C ) The superstructure of the prosthesis was split in the midline to accommodate potential transverse mandibular growth. The most posterior implant was not restored. ( D ) Labial view of the restored prosthesis.

Placement of implants into an ablative defect reconstructed using plates and screws permits the removal of the reconstruction hardware at the time of implant placement. Removal of reconstruction hardware while the patient is still growing may in some instances permit growth of the affected areas of the jaws to resume as long as it is not further constrained by dental implants or by an implant supported prosthesis. In reconstructions involving the mandibular symphysis we have employed a prosthesis designed with a split at the midline to accommodate potential transversal growth. However, in a series of five young children reconstructed with cross-arch implant-supported fixed bridges split at the midline in vascularized free fibular grafts, we have seen no separation of the right and left sides of the bridges as might be expected were the mandibles to have grown transversally in the intercuspid regions. Implants and implant supported reconstructions are not expected to grow vertically together with the rest of the developing arch. Consequently, the implant reconstruction should be remade periodically in order to avoid distortion of the occlusal plane and overeruption of the opposing dentition.

Such reconstructions can be performed in vascularized bone grafts ( Figs. 4 A– 4 K) or in free nonvascularized bone grafts ( Figs. 5 A– 5 L). The maintenance of good oral hygiene around implant reconstructions is extremely important in young children; despite parental attempts, these patients may find it challenging to keep the tissue around the implants in a healthy state (see Fig. 4 K).

Fig. 4
( A ) An aggressive central giant cell granuloma of the mandible in a 5-year-old boy seen from the labial view. ( B ) Panoramic radiograph of lesion extending from the right first premolar tooth bud to the left second premolar tooth bud. ( C ) The lesion was exposed through an intraoral chin degloving approach. ( D ) The resected mandibular specimen. ( E ) The vascularized free fibular graft is shown with the adapted reconstruction plate. ( F ) Implant placement into the fibular graft at the age of 6 years. ( G ) The reconstruction plate was removed at the time of the implant placement. ( H ) The implants were inserted as a one-staged placement. ( I ) Panoramic tomograph of the restored implants. Note that the restoration does not cross the midline. ( J ) The completed provisional restoration in the mouth. Note the split of the prosthesis at the mandibular midline. ( K ) Two years after insertion of the prosthesis, the patient began to develop inflamed areas of granulation tissue. Oral hygiene had always been a difficult issue in this child. It imperative that the reconstructive team focus on this issue from the outset.

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Jan 23, 2017 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Reconstruction of Ablative Defects Using Dental Implants
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