Lichenoid reaction associated with silver amalgam restoration in a Bombay blood group patient: A case report.

The pathogenic relationship between the oral lichenoid reaction (OLR) and dental restorative materials has been confirmed many times. An OLR affecting oral mucosa in direct contact with an amalgam restoration represents a delayed, type IV, cell mediated immune response to mercury or one of the other constituents of the dental amalgam. Bombay blood group patients are more prone to this. A case of bilateral OLR is presented, which is present in relation to amalgam restoration. The lesion healed up after the replacement of restorations with an intermediate restorative material. The clinician should be aware of all the possible pathological etiologies of white lesions. If there is any doubt about the nature or management of a usual oral lesion, a referral to an appropriate specialist is mandatory.

INTRODUCTION

The human oral mucosa is often subjected to many noxious stimuli, either hot or cold, acidic or alkaline substances, and spicy foods, among others. In the dental environment, substances identified as allergenic include local anesthetics, antibiotics, restorative materials, and latex.[1] Silver amalgam has been used as a dental restorative material for over 165 years and still it remains the most commonly placed filling material in the world.[2] Its superior compressive strength and minimal technique sensitivity makes it an ideal material for posterior restorations and core buildups.

Silver amalgam can produce hypersensitivity reaction in the oral mucosa in the form of an oral lichenoid lesion (OLL).[3] The oral lichenoid reaction (OLR) is a lesion clinically and histologically indistinguishable from the oral lichen planus (OLP). However, the OLR disappears when the causing substance is eliminated, generally a drug (antibiotics, antidepressants, antihypertensive, antiaggregants, cardiac glucosides, oral hypoglycemics, nonsteroidal anti-inflammatory agents, sympathomimetics, and vasodilators) or dental materials.[4]

H antigen is a blood group antigen present in all the individuals irrespective of blood group types. It is the precursor for the formation of A and B antigens. In people belonging to A and B blood groups, the precursor H antigen is converted to A and B antigens, respectively; whereas in O blood group individuals, it remains in the original forms. People with O blood group have the highest amount of H antigen, which affords protection against the OLP. Hence, O blood group people were least susceptible to develop the OLP, which is consistent with the results in the oral cancer patients.[5]

Amalgam associated OLLs (AAOLLs) usually appear clinically in the form of white reticular papular lesions involving mucosa occasionally with plaques and erosive, atrophic, or ulcerated areas. Contrary to the OLP, these lesions are usually unilateral and/or asymmetrical and adjacent to amalgam restorations. In terms of diagnosis, these lesions are clinical-pathological.[6]

Patch testing has been used to check their association with amalgam in an attempt to demonstrate allergy to amalgam components as well as the existence of a favorable course subsequent to coating or replacing other related restorations.[7]

It has been suggested that amalgams should be replaced in those cases in which lesions are in direct contact with the latter and whenever patch testing is positive. Although presently silver amalgams are rarely used as a sealing material in the field of restorative dentistry, many adults are still wearing restorations made of this material.[8]

CASE REPORT

A 42-year-old male patient came to the Department of Conservative and Endodontics with a complaint of fractured amalgam restoration in lower left back region of the jaw.

History of present illness

Patient was apparently alright 1 month back. Suddenly, he noticed fractured amalgam restoration in lower left back region of jaw. The patient had also given the history of burning sensation on the left and right cheek for the past 1 month. A detailed history was taken.

Examination

Oral examination revealed the presence of a white lesion on left and right buccal mucosa, adjacent to the amalgam fillings [Figure 1]. The lesions measured approximately 12.5 mm in length at the level of occlusal plane of the occluding molars extending from the region corresponding to first premolar to the second molar on the left side and 11.5mm on the right side. The lesion showed a reticular pattern with a reddish inflamed area surrounding it. The lesions were nonscrapable and tested Candida negative.

Figure 1

(a and b) Lesions on both right and left buccal mucosa present adjacent to amalgam restoration

The patient had silver amalgam restorations on teeth no. 36, 37, 38, 47.

Investigation

The patient's oral hygiene was fairly good. A cutaneous patch test was done to detect contact hypersensitivity. Alloy powder and mix were tested separately on skin on the back of the patient. The patient reported back after 48 h with the complaint of itching on the mix patch [Alloy + Hg]. Patches were removed and examined. A slight erythematous reaction was noted on mix patch area.[9]

To confirm the diagnosis biopsy of the lesion and immunofluorescence assay was done.[10]

Provisional diagnosis

A clinical diagnosis of the OLR was made.

Treatment plan

The patient was informed of the condition. It was decided to replace amalgam restoration with a nonmetallic interim restoration and follow up was advised.[3]

The replacement of amalgam restorations with interim restorative material in left lower arch is done using Type II glass ionomer cement. The patient was asked to report after 1 month. On clinical examination, there was a reduction in size and severity of the lesion only on left side. But lesion on the right side was sustained [Figure 2]. Hence, the replacement of amalgam restoration in lower right arch was also done using Type II glass ionomer cement. One more review conducted after 3 months revealed complete healing of lesion on left buccal mucosa and reduction in size and severity of the lesion on right buccal mucosa was observed. Follow-up for 1 year was taken and complete healing of the lesions on both right and left buccal mucosa was observed [Figure 3].

Figure 2

After 1 month: c) No difference in lesion on right side, d) Reduction in size of the lesion on left side. After 3 months: e) Slight reduction in lesion on right side, f) Complete healing of lesion on left side

Figure 3

After 1 year: g) complete healing of lesion on right side, h) complete healing of lesion on left side

DISCUSSION

The term “oral lichenoid lesion” (OLL) is commonly used to describe oral lichen planus (OLP) lesions that develop in contact with dental restorations, lesions associated with medications, lesions associated with graft versus host disease, and lesions associated with systemic disease. The rate of prevalence of OLL is higher in women than in men. It is most prevalent in the age group of 45-65 years. Clinically and histologically these lesions cannot be distinguished from the OLP.

Topographical relationship between the lesion and restoration is the main difference between the OLL and OLP when the medical status and type of lesions were similar. If OLL is related to a causative factor, the removal of this factor may result in resolution of the clinical lesion, which contrasts with the patients having OLP who may require palliative care and monitoring over many years.[4]

Histopathological aspects of various lichenoid lesions are not discriminative from OLP. The presence of a mixed subepithelial infiltrate, in contrast to the strict lymphohisteocytic infiltrate that defines OLP, and a deeper more diffuse distribution within the lamina-propria and superficial submucosa, focal Para keratosis, focal interruption of the granular layer, cytoid bodies in the cornified and granular layers is as marker of a lichenoid oral lesion.

There is a definitive relationship between Bombay blood group and OLP.[5] The Bombay blood group is the rarest of rare in blood groups. It is called so because Bhende et al. reported it first in Bombay (now Mumbai, India). People bearing this blood group will not possess A, B, and H antigens in their red cells, instead they have anti-A, anti-B, and anti-H antibodies.[11] The cause of H antigen deficiency is homozygous deficiency of FUT1 antigen. In oral cancer, premalignant lesions and conditions there is aberrant expression of ABH antigen. This occurs mainly because of an altered glycosylation of cell surface proteins and lipids.[4]

CONCLUSION

From this case report, it is evident that amalgam restorations may induce lichenoid reactions in susceptible individuals such as Bombay blood group patients. The typical appearance of these lesions usually confirms diagnosis in most cases. Clinical features as well as the results of skin patch testing against Hg and Silver alloy can help in the diagnosis. Several studies have shown the benefit of replacing restorations on the healing of lichenoid reactions.

Para functional habits may also exacerbate lesions close to restorations. Psychological aspects, lifestyle of patient, and genetic susceptibility have also been proposed to be the predisposing factors. Complete healing of lichenoid lesions after the replacement of dental amalgam in 28/62 (42%) patients with positive patch tests results and 3/15 (20%) patients with negative patch test results was reported by Laine et al.[12]

These lesions are rarely symptomatic, and many patients are unaware of their existence. The removal of the offending fillings may result in clearing of the lesions. Patients whose lesions are in direct contact with the fillings have a better prognosis. Amalgam removal, whenever it is necessary, should always be done using absolute isolation with rubber dam, abundant irrigation, and high-volume suction. This avoids ingestion, minimizes inhalation of mercury vapor, and largely eliminates the risk of an exacerbation of the lesion during the amalgam removal.[13]

Financial support and sponsorship

Ranbaxy Laboratory, Karad.

Conflicts of interest

There are no conflicts of interest