Lipoatrophy Associated With Maxillary Bone Graft for the Purpose of Dental Implants and Correction by Fat Grafting: A Case Report

Abstract

Lipoatrophy could be a manifestation of a metabolic disorder, pharmacological therapy, or as the result of an immune reaction in adipose tissue. Localized lipoatrophy after a dental intervention is a finding rarely described in scientific literature of head and neck pathology. A 56-year-old woman reported experiencing tissue loss on the right cheek. A maxillary bone graft for the purpose of dental implants had been performed 10 months prior to the first signs. Medical imaging showed no signs of any lytic bone lesions. A fat graft harvested from the abdomen was used to fill the deficit. For a clinician, lipoatrophy even if extremely rare should be considered among the inflammatory complications after a dento-alveolar bone graft. Especially because of its rarity, any coincidental systemic disorder should be excluded during the assessment of the condition.

Introduction

Lipoatrophy is defined by a loss in adipose tissue which is usually preceded by an inflammatory process. It could also be primary (idiopathic) or secondary, localized or diffused. Secondary lipoatrophy develops with infections, connective tissue diseases such as lupus or dermatomyositis, neoplasms like T-cell lymphoma, and drug injections. Several clinical forms have been described including annular, semicircular, abdominal, and involutional. ¹

Lipodystrophy is defined as a significant absence, reduction, or redistribution of subcutaneous fat mostly without signs of inflammation. ² It could be primary or secondary to a systemic condition such as type 2 diabetes or highly active antiretroviral therapy in human immunodeficiency virus (HIV)-infected patients. Highly active antiretroviral therapy is the most common cause of lipodystrophy worldwide and can be observed in 20% to 50% of these patients. ^3,4 Primary lipodystrophies are rare conditions with a combined prevalence of 1 in 10⁶ patients. They could be genetic or acquired, generalized or partial. Barraquer-Simons syndrome or acquired partial lipodystrophy usually consists of a symmetrical loss of adipose tissue especially in the lower limbs. It begins during puberty and mostly before 15 years of age. It is commonly seen with low level serum complement components like C3 accompanied with detectable levels of C3 nephritic factor (C3NeF). ^5,6

Alveolar preservation bone graft is a common procedure in oral surgery that is performed after the tooth extraction and before placing a dental implant if the amount of present bone is not favorable for an immediate implant placement. Based on the post-extraction configuration of the bone defect, an allogenic and/or xenogenic bone is used to maintain the alveolar bone ridge. An autologous bone graft is less frequently used because of the morbidity and also because of the proven efficiency and ease of use of non-autologous sources. To have a more predictable result, the surgeon might add osteoinductive agents to the graft like recombinant bone morphogenetic protein. A resorbable membrane of collagen is usually used for preserving the graft in place. A non-resorbable membrane could also be used but should be retracted later on during the follow-up sessions. ^{7 -14}

For the treatment of adipose tissue loss, fat injection was first described in 1893 by Franz Neuber who used a piece of upper arm to reconstruct the cheek of a patient with a large defect caused by the bone tubercular inflammation. In the 1980s, thanks to liposuction, it became possible to aspirate fat and reinject it in small volumes for correction of contour irregularities. The harvest contains adipocytes, adipose-derived stem cells, extracellular matrix, endothelial cells, vascular smooth muscle cells, and pericytes. Several researchers have emphasized the importance of excluding proinflammatory and non-viable elements such as oil, debris, blood cells, and damaged tissue before the transplantation. ¹⁵ For this reason, different techniques such as gravity separation, centrifugation (Coleman method), and washing filtration have been developed. Regardless of the preparation method, the principle for this kind of grafting is that transplanted fat needs to be in contact with living tissue. The graft cells survive by diffusion till the neovascularization happens, something that makes the long-term survival rate unpredictable. According to a prospective study on fat graft longevity to the midface, only 32% of fat transfer to this region is present after 16 months. However, this method is considered to have a definite and long-term efficacy. ^{16 -21}

Case Presentation

A 56-year-old white female was referred for a consultation by her periodentist for the evaluation of the tissue loss on the right cheek. Her medical history was limited to the hormonal replacement therapy for the menopause (Estrace 1 mg and Prometrium 100 mg per day) and a history of cholecystectomy 20 years prior. She was also taking 10 000 units of vitamin D per week. She had no known drug allergies. Revision of social history showed no tobacco usage for 4 years, 2 bottles of wine per week, and no use of any illicit substances. An oral surgery for the purpose of dental implants had been performed 10 months prior to the first manifestations of tissue loss. Prior to the procedure, local anesthesia was injected into the supraperiosteal plane with a concomitant nasopalatine nerve block. A total of 1.5 mL of Lidocain hydrochloride 2% with epinephrine 1:100 000 (Lignospan standard, Septodont, Lancaster, PA) had been injected. The surgery included the extraction of the right lateral incisor and an allogenic bone graft for the alveolar preservation by 1 g of demineralized allogenic bone DynaBlast (Keystone Dental, Inc., Burlington, MA) covered by a type I bovine collagen membrane Cytoplast RTM 15 mm × 20 mm (Osteogenics Biomedical, Inc., Lubbock, TX). The follow-up had shown good healing without any sign of infection. It is worth noting that the patient had undergone a similar surgery without any complication on the left side 3 years prior for the left lateral incisor: extraction followed by alveolar preservation with Straumann, Andover, MA AlloGraft (0.5 g of mineralized ground cancellous and 0.5 g of demineralized ground cortical bone mix) covered with the same kind of collagen membrane. The dental implant for the left lateral incisor was placed 2 years prior and it was well osseointegrated. The patient denied having any other cutaneous or soft tissue deficits.

A cranio-facial computed tomography scan with contrast (Figure 1) has showed mild asymmetry of the premaxillary soft tissue with atrophy on the right side. The absence of any osseous lesion ruled out a diagnosis of Gorham disease primarily posed by otorhinolaryngology. An erosion of the buccal cortical bone in the region of right lateral incisor where which the bone graft was performed was also noted.

Figure 1.

Axial (A) and coronal (B) sections of a computed tomography scan with radiocontrast agent showing a mild atrophy of the soft tissue on the right cheek without any subcutaneous focal lesion or underneath osseous defect. Erosion of the buccal cortical bone is noted in the edentulous region which has received the preimplant bone graft.

The extraoral examination did not reveal any submandibular or cervical lymphadenopathy. Other than the advanced atrophy of the right cheek, facial skin was normal and there was no sign of cheilitis (Figure 2). Examination of cranial nerves was normal. No dysfunction of temporomandibular joint nor masticatory apparatus was noted. Intraorally, the superior right vestibule seemed deeper because of soft tissue loss and has shown a mild superficial erythema. The graft material seemed to be well integrated and was palpable to the bottom of the right superior vestibule. The rest of the oral examination was within normal limits.

Figure 2.

Clinical photographs showing the tissue defect on left cheek in pre-op (A1 and A2) and the correction 3 months after the second intervention of lipograft (B1 and B2).

A working diagnosis of localized lipoatrophy was posed, most probably post-traumatic and iatrogenic in relation with surgical manipulation, periosteal perforation, and foreign body reaction and less probably idiopathic. An atypical form of Barrquer-Simons syndrome (acquired partial lipodystrophy) was considered possible even if much less probable. A manifestation of HIV infection, diabetes, or lupus profundus also considered less probable. A Parry-Romberg syndrome (progressive hemifacial atrophy) was excluded as there had been been no bone involvement nor any progression noted.

To exclude any coincidental or underlying systemic disorder, a thorough blood analysis was performed including erythrocyte sedimentation rate, C-reactive protein, anti-dsDNA, antinuclear antibody (ANA), rheumatoid factor, dosage of complement components C3, C1, C4, and C3NeF, lipid profile, anti-HIV (p24), glycated hemoglobin, and creatinine. The possibility of a magnetic resonance imaging or a scintigraphy and ideally a biopsy of adipose tissue to exclude a lupus profundus was also discussed. All the hematology results were negative/within normal limits except ANA 1:320 subtly positive. Further investigation in dermatology excluded the possibility of lupus.

In order to restore the facial contour on the right cheek, free fat transfer was planned under general anesthesia. Costs being covered by Medicare, 3 sets of fat injection were allowed because of high chance of partial resorption according to the literature. Abdominal fat was harvested peri-umbilically and centrifuged at 5000 rpm in a universal medical apparatus for 5 minutes based on Coleman technique. Oily supernatant and blood pellet discarded and purified lipograft by a total amount of 56 mL was reinjected to the right hemifacial via 2 incisions: a right pretragal and another one under the right internal canthus. A second intervention was performed for a final correction 1 year later. This time a total of 10 mL of purified lipograft was reinjected in right zygomatic region and superior part of the right nasogenian fold. A symmetric aspect of 2 cheeks was obtained at the end of operation. Follow-ups of 20 days and 3 months post-op have shown the preservation of this symmetry (Figure 2).

Discussion

In the case of alveolar preservation graft, like any other surgical intervention, the major post-operative complications are pain, bleeding, swelling, and infection. Hydroxyapatite might cause an inflammatory response if it is implemented in the soft tissue, ^22,23 but a foreign body reaction would usually involve a cascade of inflammation which would usually lead to foreign body giant cells formation. ²⁴ Even if theoretically possible, the inflammatory mediators in a foreign body reaction would rarely cause a complete soft tissue atrophy. This probably would be related to the individual susceptibility facing the foreign body aggression.

A facial lipoatrophy is a finding rarely discussed among the complications after an oral or maxillofacial intervention. In the head and neck region, a case of lipoatrophy has been reported postarthroscopy of temporomandibular joint. ²⁵ A case report by Wollina et al described a case of a 50-year-old female who presented with depression of soft tissue on the right side of her chin after a tooth extraction. ²⁶ Ayhan et al described a similar case of a 24-year-old female who presented with depression of the right periauricular region and right half of the mentum and tongue shortly after a molar tooth extraction. They attempt to explain the soft tissue atrophy by hypothesizing that it may be a result of vasoconstriction of some vessels due to the local anesthetics, but they could not obtain any evidence to support this hypothesis. ²⁷ Again, we could hypothesize that any kind of physical or chemical trauma could potentially lead to inflammation causing a lipoatrophy if a patient is genetically predisposed. The rarity of these kind of reactions might also suggest that they are multifactorial.

Localized after injection of the following substances has been reported in the litterature: has been reported in the literature: corticosteroids, ^{1,2,28 -37} insulin, ^{38 -43} antibiotics, ^{44 -46} methotrexate, ⁴⁷ recombinant growth hormone, ⁴⁸ soft tissue fillers, ⁴⁹ glatiramer acetate, ^{50 -52} diphtheria–pertussis–tetanus vaccine ⁵³ measles–mumps–rubella vaccine, ⁵⁴ and influenza vaccine. ⁵⁵ Most of them are associated with the involutional subtype that is characterized by a decrease in fat lobules containing small adipocytes. In these cases, the inflammatory infiltration is minimal (CD68⁺ macrophages) and is accompanied by a capillary hyperplasia. ^{56 -59} Differential diagnosis usually includes other types of lipoatrophy/lipodystrophy, post-injection panniculitis, atrophoderma, lupus profundus, and localized scleroderma. ^52,55,60 The condition mostly involves proximal extremities and buttocks and is more frequent in women. This might imply the involvement of female hormones or their receptors in the pathogenesis of this kind of lipoatrophy. ^{1,55,57,61 -64} It is worth noting that in our case the patient was receiving hormonal replacement therapy.

Conclusions

We report the case of a patient who presented localized lipoatrophy on her right cheek several months after an allogenic bone graft in premaxillary area. The imaging and hematological analyses showed no significant abnormalities. A fat graft was used to palliate the esthetic defect on facial contour. Albeit extremely rare, localized lipoatrophy near an extraction/bone grafting site may be possible and can be considered once systematic causes have been ruled out.