Abstract
The aim of this study was to report 2 novel clinical cases of reactive lesions of the peri-implant mucosa associated with titanium dental implants where metal-like particles were observed histologically. In both cases, the lesions were diagnosed as epulis, based on clinical evidence. Extirpation biopsies were carried out. Case 1 was diagnosed as pyogenic granuloma and case 2 as peripheral giant cell granuloma. The presence of metal-like particles in the tissues suggests that the etiology of the lesions might be related to the corrosion process of the metal structure. This is the first case of pyogenic granuloma to be reported in association with dental implants. All clinical cases of soft tissue lesions associated with implants should be reported to contribute to the understanding of the etiology and pathogeny of these lesions.
The gingival mucosa is an area of the oral cavity that is exposed to constant irritation. Numerous causes or irritant factors can cause a tissue response, such as inadequate chewing forces, entrapment of food debris, dental calculus, ill-fitting dental appliances or other iatrogenic factors and the presence of microorganisms that can be pathogenic in certain circumstances .
Gingival tissues can react to these irritant factors by developing a lesion commonly known as epulis in clinical practice . This term has been used to describe numerous lesions with a wide scope of histological patterns that have been classified and re-classified .
The main reactive lesions of the gingiva include: piogenous granuloma, peripheral gingival fibroma, peripheral ossifying fibroma and peripheral giant cell granuloma .
Titanium is the osseointegratable metallic biomaterial most used in dental implants as a therapeutic alternative . Although osseointegration can be successful initially, factors inherent to the implant material or the peri-implant milieu can lead to partial or complete loss of osseointegration and subsequent implant failure. Gingival hyperplasia, mucositis and peri-implantitis have been described among the soft tissue complications associated with dental implants . The causes that lead to the development of these reactive lesions associated with dental implants have not been fully elucidated. Within the context of the scarce information available on these lesions, the aim of the present study was to report 2 novel clinical cases of reactive lesions of the peri-implant mucosa associated with titanium dental implants where metal-like particles were histologically observed and might be attributed to a corrosion process.
Case 1
A 75-year-old woman in good general health presented for consultation with a tumor-like lesion on the alveolar ridge of the right lower maxilla. The lesion was associated with the cover screw of an implant that replaced the first lower right molar.
Caries was identified as the cause of tooth loss. The titanium dental implant (Titantec, Buenos Aires, Argentina, ASTM F67 grade 4, acid etched surface, 4.1 mm in diameter and 10 mm in length) had been placed 2 months previously. No alterations and/or lesions were observed in the oral mucosa or bone tissue at the time of implant placement. Following infiltration of anesthesia, a mucoperiostic flap was lifted to expose the alveolar ridge in the corresponding area. The implant, with a threaded external hex, was manually inserted until the implant’s shoulder was level with the surrounding bony crest. The implant was then sealed with a cover screw. Simple suturing was carried out. The patient was instructed to avoid tissue mobility and to rinse her mouth with 2% chlorhexidine. The sutures were removed 7 days after implant placement.
On clinical examination, the lesion, observed 2 months after implant placement, was sessile, 1 × 1 × 0.6 cm in size, had a smooth, shiny surface, was wine-red in color, and bled on palpation ( Fig. 1 ). The implant was clinically stable. No bone loss associated with the implant was observed radiographically ( Fig. 2 ). The patient’s oral hygiene was optimal, with no microbial plaque accumulation or associated trauma.
Total extirpation of the lesion with implant preservation and curettage of the bone surface were carried out. Given that the lesion was superficial and bone tissue was unaltered, tissue repair post-surgery was adequate and the esthetic result was satisfactory.
The resected tissue was fixed in 10% formalin and embedded in paraffin. Histological sections were stained with hematoxylin-eosin (H-E) or eosin alone, to facilitate the detection of potential metal particles. The histopathological analysis revealed an intense vascular proliferation with extensive areas of ulceration, mixed inflammatory infiltrate and abundant macrophages. Numerous granular, blackish, metal-like particles were identified, free and/or phagocytosed by macrophages. The loaded macrophages were detected within the tissue, mostly in a peri-vascular position, and in the blood vessels ( Fig. 3 ). Microchemical identification of the particles was attempted by optic emission spectroscopy with inductively coupled plasma (ICP-OES). No titanium was detected in the sample due to the reduced sample volume (15.1 mg) and/or the determination limit of the system. The absence of the hemosiderin pigment was confirmed by Perls’ stain.
The histopathological diagnosis was pyogenic granuloma. There were no postoperative complications. The implants were loaded at 6 months post-implantation with the corresponding prosthetic rehabilitation. The clinical and radiographic follow-up revealed no lesion recurrence at 4 years.
Case 2
A 64-year-old woman in good general health presented for consultation with a tumor-like lesion in the gingival-vestibular area of the upper maxilla at the level of teeth 2.2 and 2.3. The patient exhibited prosthetic rehabilitation with dental implants and suprastructure mobility.
The implants (Bränemark-like, 4.1 mm in diameter and 11.5 mm in length), had been in place for 12 years. The distributor of the implants is unknown. No further information is available on the implants due to the time elapsed from placement and the fact that the professional who observed the reactive lesion had not carried out the original treatment. The cause of tooth loss and the status of the oral mucosa and bone tissue at the time of implant placement are unknown.
On removing the suprastructure the exophytic lesion was observed on the vestibulo-distal side of the implant that replaced tooth 2.2. On clinical examination, the lesion was sessile, 0.6 × 0.5 × 0.4 cm in size, exhibited an irregular, reddish surface and was firm and elastic on palpation ( Fig. 4 ). The patient described a 10 month evolution of the lesion. The implants that replaced teeth 1.2, 2.1 and 2.2 were clinically stable. The suprastructure included 5 crowns supported by three implants. The anchorage screw of implant 2.1 that connected the crown to the rest of the suprastructure was fractured. Concave bone loss (goblet-shaped) was radiographically observed at the level of the implants that replaced teeth 2.1 and 2.2 ( Fig. 5 ). The patient’s oral hygiene was optimal, with no microbial plaque accumulation.
The lesion was completely extirpated, followed by significant curettage of the affected bone surface. During this surgical procedure, two-thirds of the vestibular cortical were lost at the level of implant 2.2.
The resected tissue was fixed in 10% formalin and embedded in paraffin. The tissue sections stained with H-E and eosin alone, revealed proliferating fusiform and round mesenchymal cells, highly vascularized areas and numerous multinucleated giant cells. Certain areas of the lesion surface were ulcerated. Isolated, free, blackish, metal-like particles were identified ( Fig. 6 ). The histopathological diagnosis was peripheral giant cell granuloma. There were no postoperative complications. Tissue repair was adequate but the esthetic result was not satisfactory. Controls at 2 years revealed no lesion recurrence.
