Pathologies for allergens and irritants in dentistry

Dentistry is one of the professions in which there is the most contact with a large battery of substances common to the entire population, to which must be added dental materials, which do not they can only cause injuries to patients, but also to the professionals themselves (auxiliaries, hygienists, prosthetists, dentists).

The list of irritating and sensitizing agents is immense, so we will limit ourselves to talking about those products most commonly used in the daily activity of a dental clinic.

Regarding the "allergic" concept, remember that anyone who is not allergic to any substance ceases to be so at a given moment, even with products with which they have lived all their lives. So the correct answer to the question "Are you allergic?" is: "Until now." In general terms, they are diseases caused by physical agents (dust, pollens...), chemicals (drugs, metals...) and biological agents (microorganisms, plants...) that affect certain organs, either due to an irritative toxic effect, or by triggering a reaction disproportionate of the immune system.

The clinical pictures they cause present similar symptoms (rhinitis, conjunctivitis, asthma, eczema, urticaria...) that only due to the characteristics of the causative agent and the personal and family history of immune system alterations, allow us to differentiate between a clinical picture irritant and other allergic type.

Sensitizers

They are substances that when inhaled (respiratory sensitizer) can give rise to allergic reactions in the respiratory system, or that are introduced into the body through the skin (dermal sensitizer), producing hypersensitivity that culminates in the appearance of a skin eczema.

These substances can be found within a large number of work activities. Exposure to sensitizers can and does cause significant illness and even in some cases death. Within respiratory diseases we can mention: asthma, extrinsic allergic alveolitis (EAA), rhinitis and reactive pathway dysfunction syndrome (RSDS). Among the dermatological diseases: allergic contact dermatitis, immunological contact urticaria and photoallergic contact dermatitis.

They are characterized by having an immunological pathogenesis, because there must be prior sensitization to the allergen –which can be years– and because it is more frequent in people with a personal and family history of allergic reactions.

Irritating

An irritant is a substance that deteriorates the body (skin, airways, mucosa...) of all individuals by direct action through non-immunological mechanisms.

These agents can be physical (radiation, dust, fibers...), mechanical (rubbing, trauma...), biological (secretions, infections...), and chemical products (acids, bases and solvents...).

The severity of the damage caused by an irritant will depend on its degree of toxicity, the concentration of the substance and the duration of exposure, and the route of entry into the body and from the first contact.

By the respiratory tract it can produce: rhinitis, asthma, broncho-alveolitis and pneumocomiosis.

Topically: conjunctivitis, stomatitis, irritant contact dermatitis and nonimmunological contact urticaria.

Dermatoses are usually the most common clinical conditions along with respiratory ones. They can be irritative or allergic, their prevalence varies between 1.5 and 5.4% and, in relation to the world of work, they are considered an occupational disease.

In the health field, they are due to the handling of various chemical products, sometimes as work material and others, used as hygiene or disinfection.

Eczema is usually the most common clinical picture and is characterized by: starting with very accentuated erythema, edema and pruritus; over the course of hours vesiculation begins, with multiple grouped vesicles that can come together and form larger ones and even blisters, with serous content; these break and leave small punctate exudative depressions that, if the agent has ceased, form scabs and inflammation decreases, returning the skin to its natural state in a few weeks, leaving no residual lesion (eczema does not leave a scar).

Clinical forms of contact injuries

Contact eczema or contact dermatitis (D.C.)

At the D.C. three aspects must be considered: morphology (typical eczema and atypical forms), topography (in any part of the body) and evolution, which can be acute (typical picture), subacute (attenuated symptoms and signs) and chronic (persistence of the agent little aggressive for a long period of time, tends to lichenification).

The misuse of topical medications (antihistamines, powerful corticosteroids, furantoins...) can complicate dermatitis.

The D.C. Irritative is nonspecific damage to the skin after exposure to an irritant. It comprises various clinical reactions that are influenced by the type of irritant, temperature, humidity, anatomical location, and the idiosyncrasies of the individual (age, sex, race, and previous allergies).

The D.C. Allergic is an eczematous skin reaction resulting from exposure of the skin, in previously sensitized individuals, to sensitizing or allergic substances by contact.

Often, the patient has been in contact with the substance for several years, before becoming sensitized. Substances that cause D.C. they are very varied.

Contact photodermatitis

Eczema is produced by the interaction of the skin with the result of a chemical substance foreign to the organism and electromagnetic radiation (indispensable condition).

The most important substances are: phenothizins, psoralens, NSAIDs, dyes, coal tar, antibiotics, diuretics, antifungals, fragrances, and sunscreens.

Contact urticaria

The wheal is the elementary lesion of urticaria. It is a raised skin that reflects an edema in the dermis and that lasts for a short period of time (minutes to hours).

Clinical aspects: a) Urticaria located in the contact area; b) Generalized urticaria and post-contact angioedema; c) Urticaria associated with gastrointestinal symptoms, rhinitis, asthma and conjunctivitis; and d) Urticaria associated with anaphylactic reactions.

Acute contact urticaria to latex deserves special mention due to its clinical significance, which can cause the death of the person who develops this condition. First described in 1980, it is defined as an IgE-mediated allergy to protein antigens present in natural latex and persisting in manufactured latex. Atopy and the existence of previous lesions (hand eczema) can facilitate this picture.

Clinical: it is an immediate hypersensitivity to latex that on contact with the skin begins only with itching; Subsequently, erythema, edema or hives appear in the contact area, generalized urticaria, systemic symptoms (ocular, respiratory, gastrointestinal and cardiovascular), anaphylactic shock and in very severe cases, death.

When the exposure is aerial, the symptoms can only be rhinitis, conjunctivitis or asthma. Itching, edema and risk of anaphylactic shock appear on the mucous membranes due to the greater ease of absorption of the antigen.

Pathologies due to allergens and irritant in Dentistry

Latex sensitization cross-reacts with certain fruits (banana, avocado, chestnut, kiwi, papaya, custard apple, passion fruit, mango, pineapple, peach, tomato, and wheat flour), leading to the description of latex syndrome -fruits (anaphylaxis, oral syndrome and urticaria or angioedema). Cross-reactions with some pollens and fungi have also been described, further complicating the problem.

In Dentistry, cases of allergy or hypersensitivity reaction have been reported to some components of prosthetic, orthodontic and restorative materials, among others, such as methyl methacrylate, BisGMA, alginate, plaster, eugenol, latex, metals (nickel, chrome, cobalt, mercury, gold…); disinfectants (formaldehyde, glutaraldehyde, sodium hypochlorite); iodoform pastes, calcium hydroxide, carbamide peroxide, and X-ray developer/fixer fluids.

In sensitized patients, various types of lesions are produced by contact with the oral and perioral mucosa (mucositis, lichenoid reactions, cheilitis, gingivitis, burning mouth syndrome). Special care must be taken with patients who are sensitized to latex since it is a product present in many rubber materials, and especially if they use latex gloves or rubber dams.

In professionals, sensitization and subsequent injuries are produced, fundamentally, by direct contact with the skin; on other occasions they will be by respiratory route. We must not forget that sensitization to any substance can occur outside of professional activity, just like any other person, and if you are atopic, it is more likely.

In the professional environment, you are not only in contact with dental materials, but with all kinds of substances such as soaps, disinfectants, medicines, aerosol fragrances, air fresheners, hand creams, textiles and pigments for pajamas, gowns and shoes , metal doorknobs, etc. The list of irritating and sensitizing substances is endless and new products are added every day (there are more than 5 million chemical products on the market, of which some 3,000 are known as allergens).

Reactions to latex and methacrylates are the most prevalent among dental professionals, varying the percentages between 4% and 30% depending on the different cases. Due to the multitude of sensitizing proteins in latex (heveins) and due to direct contact with the skin of the methacrylate monomers, when handling them without protection.

In the first publications that exist in the literature of symptoms related to the use of latex gloves in dentists and students (early 1990), the percentages varied according to countries between 10% and 31% in students, and from 13.7% to 22.8% in general dentists, who in turn reflected a personal history of allergies to pollen and grasses (35.5% and 30.2%), eczema (16.8% and 11, 7%) and allergies to latex (16.8% and 5.2%); from this it follows that they were more likely to have or develop skin reactions to latex gloves.

In subsequent studies, these percentages drop to figures between 3.8% and 6.2% related to greater awareness and better management of these situations, after the establishment of standards and protocols that promote the use of gloves free of powder and low in accelerating and extracting substances from latex proteins or its replacement by those of vinyl or nitrile.

Confirmation of the agent to which one is sensitized involves consulting a specialist who, after taking a detailed clinical history, will request specific complementary tests to reach a certain diagnosis, since this pathology can be the cause of an occupational disease , with the corresponding legal connotations (change of job, profession or temporary or total disability), and because the general analysis and biopsy are non-specific. These tests are:

– The puncture test or Prick test (the type I reaction is assessed, the early appearance of a wheal in the inoculation area). In some cases, such as latex sensitization, anaphylaxis has occurred, so they must be performed in a hospital setting.

– Contact tests or Patch tests (assess the type IV reaction, appearance of erythema or eczema in the contact area). The patches are placed with the standard battery of products proposed by the Spanish Contact Dermatitis Research Group and the specific ones for each professional group, which are lifted 48 hours later and read at that time and 72 and 96 hours after their placement.

– Blood tests for blastoid transformation of lymphocytes, MELISA (Memory Lymphocite Immuno-Stimulation Assay) and determinations of specific Immunoglobulins (IgE),

Prevention involves working correctly with adequate hygiene and individual protection, apart from the collective ones that the company must implement (training on products that are handled and how to protect oneself from them, and having the appropriate means to minimize risks and put them into practice).

Treatment involves avoiding contact with the irritating or sensitizing substance, and timely medical treatment to cure the lesions (corticosteroids, pure Vaseline, etc.). Topical antihistamines and anesthetics should be avoided due to their great sensitizing power. If contact continues, the lesions will not subside, or they will reappear.

The following are the agents, grouped by families, that mainly cause contact dermatitis.

The clinical pictures caused present very similar symptoms: rhinitis, conjunctivitis, asthma, eczema and hives.

Metals

The harmful effect can be caused by the metal itself, but most frequently it is caused by metal salts or by the ions released by corrosion or oxidation.

• Gold: as such it is not sensitizing, but alloys with Ni, Pd, Cu, Zn, or Ag, can cause concomitant sensitization.

• Nickel: accompanies us throughout the day (door handles, keys, coins, food, etc.). In men it has a more professional character than in women (for costume jewelery and jewelry in general). It is one of the sensitizers with the highest incidence (approximately 20% of the population). Data to take into account when making a prosthesis that contains it.

• Chromium: very ubiquitous, and the fourth most abundant element in nature. The most sensitizing form is the hexavalent. Awareness is very important, especially professionally due to the use of cement. Present in dental alloys, cleaning agents and in many industries.

• Cobalt: another ubiquitous metal, widely used (found in most cleaning agents) and sensitizer (the ion and its salts). It is found in dental alloys, B vitamins, ceramics, and resins.

• Mercury: it was the first substance described as capable of causing contact allergy by simply applying it to the skin. We can see lesions on the conjunctiva and eyelids, on the skin due to cosmetics, antiseptics, glossitis, stomatitis and generalized involvement due to accidental ingestion. It sensitizes as metal and due to its organic and inorganic salts.

• Titanium: increasingly used in implants and prostheses due to its non-sensitization (experimentally demonstrated in mice). In humans, Camarasa et al did not describe any positive case in a series of 600 patients.

• Palladium: used in the manufacture of “white gold” and in alloys. Cross-sensitization reaction with Ni is suggested.

• Platinum: in prosthetics. In addition to contact dermatitis and urticaria, rhinitis, conjunctivitis and asthma have been described.

• Silver: the pure metal does not sensitize, but its nitrate salt does. Contained in amalgams and prostheses.

• Osmium: in prostheses. Osmium oxide is highly sensitizing to the skin and toxic by air.

• Copper: in jewelery and costume jewellery, and in Dentistry as it is part of the composition of white gold and amalgams. It is more irritating than sensitizing.

• Tin: used to protect Cu. and Fe. It is sensitizing in the form of chloride.

• Iron: slightly irritating and allergic. It produces tattoos.

• Aluminum: in prostheses together with Ni and Ti, and in toothpastes.

• Zinc: in dental prostheses, cosmetics, insulin... It can sensitize.

• Beryllium: very sensitizing and possible carcinogen, it is replaced by Yttrium.

Other metals that may be present in prosthetic alloys include: rhodium, ruthenium, iridium, gallium, indium, manganese, silicon, molybdenum, tungsten, vanadium, carbon, and tungsten.

Cosmetics and perfumes

In Dentistry we find them in toothpastes and mouthwashes, soaps and cleaning and disinfection products. The most typical allergens are:

• Fragrances: in soaps and topical medicines. They stand out: aldehydes (in soaps, toothpastes, cleaning products...) and eugenol (in cements and to stabilize resin monomers). It is considered as a source of professional awareness.

• Balsam of Peru: has antiseptic, anti-inflammatory and anesthetic properties.

• Preservatives: to avoid contamination and bacterial and fungal growth. Highlights: parabens (methyl, ethyl, propyl and butyl), formaldehyde and quaternary ammoniums.

Rubber and gums

• Natural rubber (due to the additives used in its manufacture: thiuram, mercaptobenzothiazole, carbamates, thioureas, antioxidant amines derived from PPDA, pigments…).

• Synthetic rubber (styrenes, butadienes…).

• Latex: latex is extracted from the Hevea brasiliensis tree, it is a milky product that has multiple proteins (heveins, hevamine, chitinases, profilin, among others) and to which ammonium, preservatives, and 200 more chemical products are added, such as accelerators, pigments, antioxidants and activators in their manufacture that modify these proteins, causing the appearance of new sensitizers.

Plastics and resins

They are synthetic or natural products that constitute one of the main branches of the current industry, which can make us think that we live in the «Age of Plastic». In Dentistry, they are components of dental prostheses and of composites and adhesives, with dental technicians being the most affected. We are talking about monomers, polymers and copolymers as components of these substances that are obtained by the polymerization process (by addition, by condensation or by transfer of the activating group) giving rise to thermoplastic and thermosetting plastics.

Polyethylene, propylpropylene, polyvinylidene, polystyrene, polyvinyl chloride (PVC) are the plastics that are part of our daily lives (wrapping, bags, pipes, insulation, cars, toys, sporting goods...). They are sensitizing due to the presence of monomer or additives.

This section includes silicones that do not have an irritant or sensitizing capacity, unlike the other large group of substances that are resins (natural and synthetic).

• Synthetic resins: epoxy, acrylic, PTBP (contact glue), phenoplastic and aminoplast. Epoxies constitute a large family –among which those with bisphenol A and epoxy-acrylate (Bis GMA) stand out–, it can act as an irritant or sensitizer, being one of the most frequent causes of contact dermatitis, due to the epoxy group. or whole molecules as in the case of BisGMA. Acrylics are another large group that is classified as: monoacrylates and monomethylacrylates, multifunctional acrylates, acrylonitriles, acrylamides and derivatives, and cyanoacrylates. All of them are important sensitizers and also have irritant potential (dimethacrylates the most).

The prevention of these injuries depends on having good information about the risks and manipulation. It should be known that:

• If the resin is well cured, there is usually no risk of irritation or sensitization.

• The maximum power of sensitization, especially in epoxies, is in the epoxy group and is directly proportional to its molecular weight (the smaller, the greater the ability to penetrate and, therefore, to sensitize).

• Hardeners (additives) are the cause of irritation or sensitization.

• Use protective measures (gloves –preferably polyvinyl chloride, because they are not attacked by resins and catalysts–, glasses, appropriate clothing…)

• Maximum hygiene, splashes must be washed quickly with plenty of soapy water. Gloves must also be washed before being removed.

Plants and wood

They produce both type I irritative and allergic lesions (urticarizing reactions) and type IV (direct and airborne contact dermatitis, and photosensitization).

This section includes alginates, derived from algae which, due to their pigments, can cause contact dermatitis and mucositis. In atopics there may be a greater risk.

Medications

Reactions due to topical drug applications (skin or mucosa) can be manifested by type I, III or IV immunological mechanisms and by irritative mechanisms.

The influencing factors are: the sensitizing power of the drug; high concentration and the vehicle that favors absorption; occlusive cure; disruption of the skin barrier; topical route as application for systemic effect; continuous application of the drug to get a faster result.

The main sensitizers of drugs are:

• Preservative agents: parabens, sorbic acid, quaternary ammoniums (benzalkonium chloride), formaldehyde, etc.

• Local anesthetics: benzoic and “para” group: benzocaine, procaine, etc.

• Antibiotics: neomycin is largely responsible; erythromycin, clindamycin, and mupirocin are rare.

• Antifungals: the imidazole group is the major sensitizer, highlighting ketoconazole, clotrimazole, sertoconazole and, above all, tioconazole.

• Antihistamines: very photosensitizing, especially promethazine. They should not be used topically.

• Topical antiseptics: thiomerosal was the most used; piroxicam, benzoyl peroxide, nitrofurazone, and glutaraldehyde are also sensitizers.

• Corticosteroids: in dermatitis resistant to treatment with topical corticosteroids, the complete drug must be studied to rule out the corticoid itself or other components. In some countries, topical corticosteroids are among the ten most common sensitizers.

• Non-steroidal anti-inflammatory drugs: ketoprofen, piketoprofen, ibuprofen and ibuproxam, derivatives of aricalkanoic acid, benzidiamine, fepranidol and piroxicam.

• Antivirals: idoxyuridine and tromantadine are the most reviewed.

• Miscellaneous: phenylephrine, epinephrine, beta-blockers, minoxidil, and spironolactone may also sensitize.

Conclusions

After reading the article we can conclude that we live in a hostile world and any substance that is around us can be a potential enemy. Well, from the immunological point of view, that's right.

Therefore, we must be prepared and act consistently in each activity, to avoid being injured. We run physical, chemical and biological risks that can make us go through life in a less comfortable way, due to the mere fact of not having paid all the attention that was required in each case.

Regarding the subject we have discussed, the first thing is to know ourselves, that is, how our immune system responds, because if we have a basic alteration (atopy), we run a greater risk of sensitization. Then, to know the products that we handle most frequently, both in the work environment and at home or other activities, to minimize contact with those substances that may be harmful and, if it is not possible to avoid it, put the appropriate measures (barriers , handling, hygiene…) so that it does not occur, since, no matter how small the exposure may seem, sensitization can develop.