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Adverse hypersensitivity reactions in orthodontics
Adverse Hypersensitivity Reactions in Orthodontics Luis P. Leite and Ronald A. Bell Among health care workers and patients, material reactions of both an irritant and hypersensitivity nature are not uncommon. These reactions can also occur on the everyday practice of orthodontics. The most common and problematic hypersensitivity reactions in orthodontic practice are due to the use of latex-based products and to alloy components of metal-based orthodontic appliances. This article reviews the implications of such reactions and provides suggestions for their management in the orthodontic office. Semin Orthod 10:240-243 © 2004 Elsevier Inc. All rights reserved.
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n modern orthodontic practice, adverse patient reactions to orthodontic materials are of both an irritant and a hypersensitivity nature. Although reactions of irritant origin are usually associated with direct friction between soft tissues and parts or accessories of the orthodontic appliances, hypersensitivity reactions are related to the antigenicity of some materials that results in an adverse patient response. Adverse hypersensitivity reactions are manifested most often as allergic contact dermatitis (ACD) of the face and neck; but mucosal and gingival reactions, as well as a potential general dermal and systemic reaction, can occur in unusual circumstances. The most common and problematic hypersensitivity reactions in orthodontic practice are due to the use of latexbased products and to the alloy components of metal-based orthodontic appliances. Addressing the most likely hypersensitivity reactions in the practice of orthodontics, this article will review the implications of latex- and metal-based allergens and provide suggestions for management of such reactions in the orthodontic office.
Latex-Based Allergic Reactions Allergic-type reactions to natural rubber latex have increased considerably since the 1980s and have become a significant problem in affecting patients and health care workers in general1,2 as well as dental professionals and dental patients.3,4 The increase in latex allergic reactions has been primarily attributed to the establishment of Universal Precautions by the Centers for Disease Control and Prevention and the atDepartment of Pediatric Dentistry and Orthodontics, College of Dental Medicine, Medical University of South Carolina, Charleston, SC. Address correspondence to: Luis P. Leite, DMD, MS, Associate Professor and Chairman, Department of Pediatric Dentistry and Orthodontics, Medical University of South Carolina, 25 Bee Street, Box 250126 Charleston, SC 29425; Phone: 843-792-3916; Fax: 843-792-3917; E-mail: [email protected].
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tendant increased use of latex-based gloves. Disposable medical gloves, particularly powdered gloves, are considered the major reservoir of latex allergens in health care.5 The aerosolization of the powder that may have bound with the latex protein antigen during donning or removal of gloves has been associated with heightened exposure. Although latexbased gloves are a primary consideration in orthodontic practice, elastic bands represent another potential source of latex allergy protein that must be factored into the equation. Two distinct types of allergic reactions to natural rubber latex are described in the literature.1,6,7 Type I hypersensitivity to natural rubber latex represents an immediate antibodymediated allergic response to multiple proteins on the latex product. A type I immunological reaction to latex protein components may be responsible for a serious and potentially life-threatening systemic immune allergic episode. A type I reaction occurs within minutes or as long as several hours after direct skin or mucosal contact with the allergen. Although fewer than 1% of the general population are reported to be diagnosed with potential type I natural rubber hypersensitivity based on skin prick test results,8 a higher prevalence of between 6% and 12% is reported among dental professionals.9-12 In addition to a detailed medical history, which might document a prior episode, diagnosis of potential type I hypersensitivity in an individual should include identification of sources of natural rubber latex product exposure and any other previous allergic reactions. Patients at particular risk of allergy to natural rubber latex are those with a history of atopy, those who have had repeated operations and extensive contact with rubber surgical drains and tubes, and those with spina bifida.1,7,13 A history of itching and redness from contact with balloons, rubber dams, and so on, as well as other allergies such as hay fever, asthma, eczema, and contact dermatitis, can also be taken as potential risk factors. Food allergy can also point to a potential latex allergy with some
Adverse hypersensitivity reactions fruits such as banana, avocado, passion fruit, kiwi, and chestnuts having proteins that are capable of cross-reacting with latex proteins. These foods can thereby act as a possible mode of sensitization to the natural rubber latex materials.14-19 Clinical tests, of which the skin prick test is considered the most accurate, can determine the presence of circulating antinatural rubber latex antibodies.20,21 However, although easy and quick, reagents for the skin prick test are not widely available and other less sensitive clinical tests are used routinely. Multiple testing is recommended for increased accuracy of diagnosis.22,23 A more delayed reaction, known clinically as type IV hypersensitivity to natural rubber latex, usually presents a reaction localized to the area of skin contact, thus the more common name of allergic contact dermatitis.1,6,7 This generally localized reaction is typically characterized by diffuse or patchy eczema on the contact area. It is often accompanied initially by itching, redness, and vesicle formation, which later evidence dry skin, fissures, and sores. Initial signs of reaction develop in minutes to hours and may persist for several weeks. These reactions are not considered life-threatening but can cause permanent damage to the skin if mismanaged or left untreated. Type IV hypersensitivity is usually an allergic reaction to one or more of the compounding chemicals added to liquid natural rubber latex during the manufacturing process. Definitive diagnosis should be based on medical history, analysis of symptoms, and a positive skin reaction to specific chemicals present in natural rubber latex products. Patch testing, which consists of a series of allergens applied to the upper back for 24 to 48 hours, is followed by a specialist examination for 1 to 7 days after the patches are removed.24 Positive testing reveals areas of red and inflamed skin under the patches, indicative of an allergy to the applied chemical. Among health care workers, the risk of becoming sensitive to latex protein is increased by prolonged and repeated exposure to the allergen. In the case of latex-based clinical gloves and the multiple potential allergens associated with their use, the response is not necessarily a true latex allergy; but rather an allergic contact dermatitis to the base rubber material or associated products. During the processing of untreated natural latex, ammonia and other chemicals such as thiurams, carbamates, and mercaptobenzothiazoles are added as accelerators or antioxidants during the manufacture of latex-based products. These compounds are thought to function as possible allergens in the final product.1,7,25,26 In addition, distribution of some natural rubber latex products with higher latex protein content than traditional sources may result from insufficient leaching times during the manufacturing process. During production of latex-based gloves, the glove is soaked in hot water to complete the curing process. It is during this stage that protein allergens are drawn toward the heat source and toward the surface of the glove. The glove is then turned inside out before packing, resulting in the concentrated protein latex allergens being closest to the skin surface of the operator. Common initial signs of allergic reaction among health care workers is erythema on the backs of the hands and between the
241 fingers. Once the dermatitis extends, the allergens will have access to the bloodstream through breaks in the epithelial layer, leading to an increased production of antibodies to the allergen. Patients will for the most part have a similar localized reaction at first contact with allergens from latex gloves or other products. The typical response is the development of a circumoral erythema, which usually represents a type IV reaction. Unfortunately, no single natural rubber latex allergen can be used to predict product allergenicity.7,26 In the dental office, natural rubber latex allergic patients must be clearly identified in their records to prevent inadvertent use of natural rubber latex-containing products. The rule is simple: natural rubber gloves should not be used by or near individuals with a known type I hypersensitivity. This rule applies regardless of the manufacturer’s stated protein levels or safety claims. This is because total protein and antigenic protein values do not directly correlate. In sum, so-called low-protein gloves can contain higher levels of natural rubber latex allergens than gloves with higher levels of total protein.8,14 Thus, the best management of natural rubber latex hypersensitivity is the practice of avoiding contact with the product and use of alternative products made of synthetic rubber or plastic. Natural rubber latex gloves should be substituted with alternative ones made of other components such as nitrile, neoprene, vinyl, polyurethane, and styrenebased rubbers or blends of these synthetic materials.1,7,10,27 In addition, the use of powder-free gloves will diminish the amount of aerosolized allergens. Importantly, if an individual has been diagnosed with allergic contact dermatitis to a specific chemical on natural rubber latex gloves; similar chemical additives are likely to be present on nitrile and neoprene gloves. In this case, gloves made of vinyl, polyurethane, and styrene-based rubbers, all of which are not vulcanized, should be utilized. Although a safer alternative to help prevent hypersensitivity reactions to the latex-related materials, these nonvulvanized products may contain allergenic plasticizers, epoxy resins, and other added stabilizers and fungicides that can still trigger an allergic contact dermatitis in certain patients. For any kind of natural rubber latex hypersensitivity reaction, topical medicaments and barrier creams can potentially worsen skin symptoms and should therefore be avoided.1,27 While total elimination of natural rubber latex products present in the orthodontic office may seem unreasonable, the goal should be to significantly reduce any patient exposure to these elements on a routine basis. Additionally, more frequent office cleanings, air-duct filter changes and cleanings, and early morning appointments can reduce patient exposure to airborne natural rubber latex particles. In certain cases appropriate treatment may have to include administration of pretreatment antihistamines. In the event of a severe type I reaction, emergency procedures such as administration of epinephrine are recommended. Finally, proper education of patients and workers regarding natural rubber latex allergies is a very important component in management of these cases. The education process should involve training on proper identification of natural rubber latex products, recog-
242 nition of allergy symptoms, and initiation of appropriate treatment.
Metal-Based Allergic Reactions The metal components of orthodontic appliances are generally composed of 18/8 stainless steel (18% chromium and 8% nickel). Both of these metal components are known allergens, but the nickel in particular is considered a common cause of contact allergy.28-30 Since orthodontic appliances almost always consist of metallic components, leaching of these elements may be a potential trigger to an allergic reaction. This consideration receives even greater attention with the expanded use of nickel titanium alloys, which contain up to 70% nickel. Nickel is the most common metal-based contact allergy among women, with the incidence of nickel sensitivity in the female population reported as high as 30% compared with only 3% of males among the studied individuals.28-30 A key element in a study by Romageura and colleagues31 was the finding that nickel sensitivity was higher among subjects with a history of pierced ears; there was 31% prevalence compared with subjects without pierced ears at 2% prevalence. Other studies have reported lower percentages of individuals with nickel sensitivity— on the order of no more than 10% in the general population.28,29 These studies have generally found females 10 times more likely than males to express sensitivity to nickel-based metals. Turning to studies of nickel hypersensitivity that specifically target the issue in orthodontic patients, a study by Bass and colleagues32 of 29 subjects (18 female, 11 male) reported an initial positive skin patch test to nickel sulfate in five of the female patients and in none of the male patients. Importantly, these five subjects plus the negative patch-testers were followed over the course of treatment after banding and bracketing with fixed stainless steel appliances. None of the positive or negative test patients evidenced inflammatory reactions or discomfort as a result of the orthodontic appliances. Two of the original negative test result patients, one female and one male, converted to a positive patch test to nickel. Again, no localized allergic-type responses were noted relative to the appliances. The authors concluded that the nickel-containing appliances had no allergic effects on the oral tissues, although the appliances may play a role in inducing nickel sensitivity. In the study by Romageura and colleagues previously cited relative to the frequency of nickel sensitivity in 700 Finnish adolescents and a history of ear piercing, the population included 476 subjects with a history of orthodontic treatment using metallic appliances. The study concluded orthodontic treatment did not affect the prevalence or risk of nickel hypersensitivity. None of the subjects with fixed orthodontic appliances before ear piercing had a positive sensitivity test to nickel. Staerkjaer and Menne33 also reported no allergic reactions of the adjacent oral mucosal from orthodontic appliances in nickel-sensitive patients. The issue of nickel-containing intraoral metal devices has also received attention in the prosthetic and restorative areas. Spiechowicz and colleagues34 reported on 10 patients with positive history of
L.P. Leite and R.A. Bell recurrent hypersensitivity reactions to nickel patch tests and who had nickel-containing prosthetic devices. No intraoral tissue reactions were found in relation to the prosthetic devices. The same conclusion was drawn by Jones and colleagues35 in the examination of five subjects with positive nickel patch tests who wore very high nickel (70% nickel)containing oral prosthesis. Such high nickel-containing metals reported in the Jones and colleagues35 study leads to the issue of what happens in the oral environment and the release of nickel from metal devices in order for the metal to act as an allergen. Nickel release from metal-based orthodontic materials has been demonstrated in several in vitro studies36-38 and in vivo assessments.39,40 These studies clearly show some corrosion of intraoral orthodontic components over time. The in vitro corrosion study by Grimsdottir and colleagues37 reported that nickel release from orthodontic metal appliances is most related to the solder composition and manufacturing of the appliances rather than being directly related to the actual nickel content. The study analyzed face bows, brackets, molar bands, and both stainless steel and nickel titanium arch wires for nickel release when stored in physiologic saline. The analysis indicated that appliances using silver and gold solders (eg, face bows and molar bands) showed enhanced release of nickel and chromium. In contrast, alloys containing titanium, for example arch wires, released little nickel when tested under the static conditions of this study. As noted by these studies, titanium has the advantage of being highly resistant to corrosion and may bind the nickel from release in these in vitro studies. What is unknown is what happens when friction of the arch wires in brackets might enhance the release of metal components from the appliances. Despite the research evidence to suggest otherwise, there have been several case reports of localized allergic responses credited to nickel-containing orthodontic appliances in the literature.41-46 Although each of these case reports is anecdotal and not conclusive to orthodontic appliances being the definitive causative agent, an associative link is a logical premise, given the individual presentations. The issue of possible nickel allergic responses in orthodontic patients is further expanded in terms of patient and clinician perspectives. In a survey of Norwegian orthodontists by Jacobsen and Hensten-Patterson,30 participants were asked to assess the number and nature of adverse reactions among their patients and to relate them to materials or treatment provided. The reactions reported were divided into dermal (extraoral) and intraoral/systemic reactions. Dermal reactions reported included redness, irritation, itching eczema, soreness, fissuring, and desquamation most often attributed to a metal extraoral (eg, headgear face bow) component of the appliances. Intraoral reactions included redness, swelling, itching and soreness of the lips and oral mucosa, and inflammation of the gingival tissues. Occasionally, symptoms such as fever, compatible with a general allergic reaction, were reported. Although not all the symptoms were attributed to the presence of metal components, they were assumed to be the primary allergens in these reported cases of hypersensitivity reactions.
Adverse hypersensitivity reactions In summary, the research literature suggests that metalbased orthodontic appliances do not increase the risk for nickel hypersensitivity to patients. Our current knowledge of intraoral orthodontic appliance corrosion patterns and the rare occurrence of possible nickel allergic responses in patients, even those with positive patch tests, suggests that concerns about sensitizing orthodontic patients to nickel are not supported in the literature. However, it would seem that caution and close monitoring should be exercised in patients with a defined history of atopic dermatitis to nickel-containing metals but that orthodontic treatment avoidance is unnecessary.
References 1. ADA Council on Scientific Affairs. The dental team and latex hypersensitivity. J Am Dent Assoc. 130(2):257-264, 1999 2. Slater JE: Allergic reactions to natural rubber. Ann Allergy 68:203-209, 1992 3. Smart ER, Macleod RI, Lawrence CM: Allergic reactions to rubber gloves in dental patients: report of three cases. Br Dent J 172:445-447, 1992 4. Wrangsjo K, Osterman K, Van Hage-Hamsten M. Glove-related skin symptoms among operating theatre and dental care unit personnel (II). Clinical examination, tests and laboratory findings indicating latex allergy. Contact Dermatitis 30:139-143, 1994 5. Beezhold D, Beck W: Surgical glove powders bind latex antigens. Arch Surg 127:1354-1357, 1992 6. Adams RM, Fletcher: J. Occupational skin disease, ed. 3. Philadelphia: W.B. Saunders Co. 1999. 7. Hammann CP, Rodgers PA, Sullivan K: Management of dental patients with allergies to natural rubber latex. Gen Dentistry 526-536, 2002 8. Yeang HY, Chow KS, Yusof F, et al: Appraisal of latex glove proteins in the induction of sensitivity to multiple latex allergens. J Investig Allergol Clin Immunol 10:215-222, 2000 9. Liss GM, Sussman GL: Latex sensitization: Occupational versus general population prevalence rates. Am J Int Med 35:196-200, 1999 10. Hamann CP, Turjanmaa K, Rietschel R, et al: Natural rubber latex hypersensitivity: Incidence and prevalence of Type I allergy in the dental professional. J Am Dent Assoc 129:43-54, 1998 11. Tarlo SM, Sussman GL, Holness DL: Latex sensitivity in dental students and staff: A cross-sectional study. J Allergy Clin Immunol 99:396-401, 1997 12. Safadi GS, Safadi TJ, Terezhalmy GT, et al: Latex hypersensitivity: Its prevalence among dental professionals. J Am Dent Assoc 127:83-88, 1996 13. Snyder HA, Settel S: The rise in latex allergy–implications for the dentist. J Am Dent Assoc 125:1089-1097, 1994 14. Yip E, Palosuo T, Alenius H, et al: Correlation between total extractable protein and allergen levels of natural rubber latex gloves. J Nat Rubber Res 12:120-130, 1997 15. Chen Z, Posch A, Cremer R, et al: Identification of hevein (Hev b 6.02) in Hevea latex as a major cross-reacting allergen with avocado fruit in patients with latex allergy. J Allergy Clin Immunol 102:476-481, 1998 16. Levy DA, Mounedji D, Noirot C, et al: Allergic sensitization and clinical reactions to latex, food and pollen in adult patients. Clin Exp Allergy 30:270-275, 2000 17. Garcia Ortiz JC, Moyano JC, Alvarez M, et al: Latex allergy in fruitallergic patients. Allergy 53:532-536, 1998 18. Tucke J, Posch A, Baur X, et al: Latex Type I sensitization and allergy in children with atopic dermatitis. Evaluation of cross-reactivity to some foods. Pediatr Allergy Immunol 10:160-167, 1999 19. Brehler R, Theissen U, Mohr C, et al: Latex-fruit syndrome: Frequency of cross-reacting IgE antibodies. Allergy 52:404-410, 1997 20. Blanco C, Carrillo T, Ortega N, et al: Comparison of skin-prick test and
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specific serum IgE determination for the diagnosis of latex allergy. Clin Exp Allergy 28:971-976, 1998 Guber C, Buck D, Wahn U, et al: Is there a role for immunoblots in the diagnosis of latex allergy? Intermethod comparison of in vitro and in vivo IgE assays in spina bifida patients. Allergy 55:476-483, 2000 Kim KT, Safadi GS, Sheikh KM: Diagnostic evaluation of Type I latex allergy. Ann Allergy Ashma Immunol 80:66-70, 1998 Pridgeon C, Wild G, Ashworth F, et al: Assessment of latex allergy in a healthcare population: Are the available tests valid? Clin Exp Allergy 30:1444-1449, 2000 Rietschel RL, Fowler JF Jr: Chapter 2: Practical aspects of patch testing. In: Fisher’s Contact Dermatitis, ed5. Baltimore: Lippincott, Williams & Wilkins; 2001. Field EA, Fay MF: Issues of latex safety in dentistry. Br Dent J 179:247253, 1995 Posch A, Chen Z, Raulf-Heimsoth M, et al: Latex allergens. Clin Exp Allergy 28:134-140, 1998 Hamilton RG, Brown RH: Impact of personal avoidance practices on health care workers sensitized to natural rubber latex. J Allergy Clin Immunol 105:839-841, 2000 Peltonen L: Nickel sensitivity in the general population. Contact Dermatitis 5:27-32, 1979 Shubert H, Berova N, Czernielewski A, et al: Epidemiology of nickel allergy. Contact Dermatitis 16:122-128, 1987 Jacobsen N, Hensten-Pattersen A: Occupational health problems and adverse patient reactions in orthodontics. Eur J Orthod 11:254-264, 1989 Romageura C, Grimalt F, Vilaplana J: Contact dermatitis from nickel: an investigation of its sources. Contact Dermatitis 19:52-57, 1988 Bass JK, Fine H, Cisneros GJ: Nickel sensitivity in the orthodontic patient. Am J Orthod Dentofac Orthop 103:280-285, 1993 Starkjaer L, Menne T: Nickel allergy and orthodontic treatment. Eur J Orthod 12:284-289, 1990 Spiechowicz E, Glantz O, Axell T, et al: Oral exposure to a nickelcontaining dental alloy of persons with hypersensitive skin reactions to nickel. Contact Dermatitis 10:206-211, 1984 Jones TK, Hansen CA, Singer MT, et al: Dental implications of nickel hypersensitivity. J Prosth Dent 56:507-509, 1986 Park HY, Shearer TR: In vitro release of nickel and chromium from simulated orthodontic appliances. Am J Orthod Dentofac Orthop 84: 156-159, 1983 Grimsdottir MR, Gjerdet NR, Hensten-Pattersen A: Composition and in vitro corrosion of orthodontic appliances. Am J Orthod Dent Orthop 101:525-532, 1992 Barrett RD, Bishara SE, Quinn JK: Biodegradation of orthodontic appliances: part I, biodegradation of nickel and chromium in vitro. Am J Orthod Dentofac Orthop 103:8-14, 1993 Maijer R, Smith DC: Corrosion of orthodontic bracket bases. Am J Orthod 81:43-48, 1982 Gjerdet NR, Erichsen ES, Remlo HE, et al: Nickel and iron in saliva of patients with fixed orthodontic appliances. Acta Odontol Scand 49:7378, 1991 Dunlap CL, Vincent SK, Barker BF: Allergic reaction to orthodontic wire: report of a case. J Am Dent Assoc 118:449-450, 1989 Trombelli L, Virgili A, Corazza M, et al: Systemic contact dermatitis from an orthodontic appliance. Contact Dermatitis 27:259-260, 1992 Veien NK, Borchorest E, Hattel T, et al: Stomatitis or systemicallyinduced contact dermatitis from metal wire in orthodontic materials. Contact Dermatitis 30:210-213, 1995 Kerouso H, Kanerva L: Systemic contact dermatitis caused by nickel in a stainless steel orthodontic appliance. Contact Dermatitis 36:112-113, 1997 De Silva BD, Doherty VR: Nickel allergy from orthodontic appliances. Contact Dermatitis 42:102-103, 2000 Mancuso G, Berdondini RM: Eyelid dermatitis and conjunctivitis as sole manifestations of allergy to nickel in an orthodontic appliance. Contact Dermatitis 46:245, 2002
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n modern orthodontic practice, adverse patient reactions to orthodontic materials are of both an irritant and a hypersensitivity nature. Although reactions of irritant origin are usually associated with direct friction between soft tissues and parts or accessories of the orthodontic appliances, hypersensitivity reactions are related to the antigenicity of some materials that results in an adverse patient response. Adverse hypersensitivity reactions are manifested most often as allergic contact dermatitis (ACD) of the face and neck; but mucosal and gingival reactions, as well as a potential general dermal and systemic reaction, can occur in unusual circumstances. The most common and problematic hypersensitivity reactions in orthodontic practice are due to the use of latexbased products and to the alloy components of metal-based orthodontic appliances. Addressing the most likely hypersensitivity reactions in the practice of orthodontics, this article will review the implications of latex- and metal-based allergens and provide suggestions for management of such reactions in the orthodontic office.
Latex-Based Allergic Reactions Allergic-type reactions to natural rubber latex have increased considerably since the 1980s and have become a significant problem in affecting patients and health care workers in general1,2 as well as dental professionals and dental patients.3,4 The increase in latex allergic reactions has been primarily attributed to the establishment of Universal Precautions by the Centers for Disease Control and Prevention and the atDepartment of Pediatric Dentistry and Orthodontics, College of Dental Medicine, Medical University of South Carolina, Charleston, SC. Address correspondence to: Luis P. Leite, DMD, MS, Associate Professor and Chairman, Department of Pediatric Dentistry and Orthodontics, Medical University of South Carolina, 25 Bee Street, Box 250126 Charleston, SC 29425; Phone: 843-792-3916; Fax: 843-792-3917; E-mail: [email protected].
240
1073-8746/04/$-see front matter © 2004 Elsevier Inc. All rights reserved. doi:10.1053/j.sodo.2004.09.002
tendant increased use of latex-based gloves. Disposable medical gloves, particularly powdered gloves, are considered the major reservoir of latex allergens in health care.5 The aerosolization of the powder that may have bound with the latex protein antigen during donning or removal of gloves has been associated with heightened exposure. Although latexbased gloves are a primary consideration in orthodontic practice, elastic bands represent another potential source of latex allergy protein that must be factored into the equation. Two distinct types of allergic reactions to natural rubber latex are described in the literature.1,6,7 Type I hypersensitivity to natural rubber latex represents an immediate antibodymediated allergic response to multiple proteins on the latex product. A type I immunological reaction to latex protein components may be responsible for a serious and potentially life-threatening systemic immune allergic episode. A type I reaction occurs within minutes or as long as several hours after direct skin or mucosal contact with the allergen. Although fewer than 1% of the general population are reported to be diagnosed with potential type I natural rubber hypersensitivity based on skin prick test results,8 a higher prevalence of between 6% and 12% is reported among dental professionals.9-12 In addition to a detailed medical history, which might document a prior episode, diagnosis of potential type I hypersensitivity in an individual should include identification of sources of natural rubber latex product exposure and any other previous allergic reactions. Patients at particular risk of allergy to natural rubber latex are those with a history of atopy, those who have had repeated operations and extensive contact with rubber surgical drains and tubes, and those with spina bifida.1,7,13 A history of itching and redness from contact with balloons, rubber dams, and so on, as well as other allergies such as hay fever, asthma, eczema, and contact dermatitis, can also be taken as potential risk factors. Food allergy can also point to a potential latex allergy with some
Adverse hypersensitivity reactions fruits such as banana, avocado, passion fruit, kiwi, and chestnuts having proteins that are capable of cross-reacting with latex proteins. These foods can thereby act as a possible mode of sensitization to the natural rubber latex materials.14-19 Clinical tests, of which the skin prick test is considered the most accurate, can determine the presence of circulating antinatural rubber latex antibodies.20,21 However, although easy and quick, reagents for the skin prick test are not widely available and other less sensitive clinical tests are used routinely. Multiple testing is recommended for increased accuracy of diagnosis.22,23 A more delayed reaction, known clinically as type IV hypersensitivity to natural rubber latex, usually presents a reaction localized to the area of skin contact, thus the more common name of allergic contact dermatitis.1,6,7 This generally localized reaction is typically characterized by diffuse or patchy eczema on the contact area. It is often accompanied initially by itching, redness, and vesicle formation, which later evidence dry skin, fissures, and sores. Initial signs of reaction develop in minutes to hours and may persist for several weeks. These reactions are not considered life-threatening but can cause permanent damage to the skin if mismanaged or left untreated. Type IV hypersensitivity is usually an allergic reaction to one or more of the compounding chemicals added to liquid natural rubber latex during the manufacturing process. Definitive diagnosis should be based on medical history, analysis of symptoms, and a positive skin reaction to specific chemicals present in natural rubber latex products. Patch testing, which consists of a series of allergens applied to the upper back for 24 to 48 hours, is followed by a specialist examination for 1 to 7 days after the patches are removed.24 Positive testing reveals areas of red and inflamed skin under the patches, indicative of an allergy to the applied chemical. Among health care workers, the risk of becoming sensitive to latex protein is increased by prolonged and repeated exposure to the allergen. In the case of latex-based clinical gloves and the multiple potential allergens associated with their use, the response is not necessarily a true latex allergy; but rather an allergic contact dermatitis to the base rubber material or associated products. During the processing of untreated natural latex, ammonia and other chemicals such as thiurams, carbamates, and mercaptobenzothiazoles are added as accelerators or antioxidants during the manufacture of latex-based products. These compounds are thought to function as possible allergens in the final product.1,7,25,26 In addition, distribution of some natural rubber latex products with higher latex protein content than traditional sources may result from insufficient leaching times during the manufacturing process. During production of latex-based gloves, the glove is soaked in hot water to complete the curing process. It is during this stage that protein allergens are drawn toward the heat source and toward the surface of the glove. The glove is then turned inside out before packing, resulting in the concentrated protein latex allergens being closest to the skin surface of the operator. Common initial signs of allergic reaction among health care workers is erythema on the backs of the hands and between the
241 fingers. Once the dermatitis extends, the allergens will have access to the bloodstream through breaks in the epithelial layer, leading to an increased production of antibodies to the allergen. Patients will for the most part have a similar localized reaction at first contact with allergens from latex gloves or other products. The typical response is the development of a circumoral erythema, which usually represents a type IV reaction. Unfortunately, no single natural rubber latex allergen can be used to predict product allergenicity.7,26 In the dental office, natural rubber latex allergic patients must be clearly identified in their records to prevent inadvertent use of natural rubber latex-containing products. The rule is simple: natural rubber gloves should not be used by or near individuals with a known type I hypersensitivity. This rule applies regardless of the manufacturer’s stated protein levels or safety claims. This is because total protein and antigenic protein values do not directly correlate. In sum, so-called low-protein gloves can contain higher levels of natural rubber latex allergens than gloves with higher levels of total protein.8,14 Thus, the best management of natural rubber latex hypersensitivity is the practice of avoiding contact with the product and use of alternative products made of synthetic rubber or plastic. Natural rubber latex gloves should be substituted with alternative ones made of other components such as nitrile, neoprene, vinyl, polyurethane, and styrenebased rubbers or blends of these synthetic materials.1,7,10,27 In addition, the use of powder-free gloves will diminish the amount of aerosolized allergens. Importantly, if an individual has been diagnosed with allergic contact dermatitis to a specific chemical on natural rubber latex gloves; similar chemical additives are likely to be present on nitrile and neoprene gloves. In this case, gloves made of vinyl, polyurethane, and styrene-based rubbers, all of which are not vulcanized, should be utilized. Although a safer alternative to help prevent hypersensitivity reactions to the latex-related materials, these nonvulvanized products may contain allergenic plasticizers, epoxy resins, and other added stabilizers and fungicides that can still trigger an allergic contact dermatitis in certain patients. For any kind of natural rubber latex hypersensitivity reaction, topical medicaments and barrier creams can potentially worsen skin symptoms and should therefore be avoided.1,27 While total elimination of natural rubber latex products present in the orthodontic office may seem unreasonable, the goal should be to significantly reduce any patient exposure to these elements on a routine basis. Additionally, more frequent office cleanings, air-duct filter changes and cleanings, and early morning appointments can reduce patient exposure to airborne natural rubber latex particles. In certain cases appropriate treatment may have to include administration of pretreatment antihistamines. In the event of a severe type I reaction, emergency procedures such as administration of epinephrine are recommended. Finally, proper education of patients and workers regarding natural rubber latex allergies is a very important component in management of these cases. The education process should involve training on proper identification of natural rubber latex products, recog-
242 nition of allergy symptoms, and initiation of appropriate treatment.
Metal-Based Allergic Reactions The metal components of orthodontic appliances are generally composed of 18/8 stainless steel (18% chromium and 8% nickel). Both of these metal components are known allergens, but the nickel in particular is considered a common cause of contact allergy.28-30 Since orthodontic appliances almost always consist of metallic components, leaching of these elements may be a potential trigger to an allergic reaction. This consideration receives even greater attention with the expanded use of nickel titanium alloys, which contain up to 70% nickel. Nickel is the most common metal-based contact allergy among women, with the incidence of nickel sensitivity in the female population reported as high as 30% compared with only 3% of males among the studied individuals.28-30 A key element in a study by Romageura and colleagues31 was the finding that nickel sensitivity was higher among subjects with a history of pierced ears; there was 31% prevalence compared with subjects without pierced ears at 2% prevalence. Other studies have reported lower percentages of individuals with nickel sensitivity— on the order of no more than 10% in the general population.28,29 These studies have generally found females 10 times more likely than males to express sensitivity to nickel-based metals. Turning to studies of nickel hypersensitivity that specifically target the issue in orthodontic patients, a study by Bass and colleagues32 of 29 subjects (18 female, 11 male) reported an initial positive skin patch test to nickel sulfate in five of the female patients and in none of the male patients. Importantly, these five subjects plus the negative patch-testers were followed over the course of treatment after banding and bracketing with fixed stainless steel appliances. None of the positive or negative test patients evidenced inflammatory reactions or discomfort as a result of the orthodontic appliances. Two of the original negative test result patients, one female and one male, converted to a positive patch test to nickel. Again, no localized allergic-type responses were noted relative to the appliances. The authors concluded that the nickel-containing appliances had no allergic effects on the oral tissues, although the appliances may play a role in inducing nickel sensitivity. In the study by Romageura and colleagues previously cited relative to the frequency of nickel sensitivity in 700 Finnish adolescents and a history of ear piercing, the population included 476 subjects with a history of orthodontic treatment using metallic appliances. The study concluded orthodontic treatment did not affect the prevalence or risk of nickel hypersensitivity. None of the subjects with fixed orthodontic appliances before ear piercing had a positive sensitivity test to nickel. Staerkjaer and Menne33 also reported no allergic reactions of the adjacent oral mucosal from orthodontic appliances in nickel-sensitive patients. The issue of nickel-containing intraoral metal devices has also received attention in the prosthetic and restorative areas. Spiechowicz and colleagues34 reported on 10 patients with positive history of
L.P. Leite and R.A. Bell recurrent hypersensitivity reactions to nickel patch tests and who had nickel-containing prosthetic devices. No intraoral tissue reactions were found in relation to the prosthetic devices. The same conclusion was drawn by Jones and colleagues35 in the examination of five subjects with positive nickel patch tests who wore very high nickel (70% nickel)containing oral prosthesis. Such high nickel-containing metals reported in the Jones and colleagues35 study leads to the issue of what happens in the oral environment and the release of nickel from metal devices in order for the metal to act as an allergen. Nickel release from metal-based orthodontic materials has been demonstrated in several in vitro studies36-38 and in vivo assessments.39,40 These studies clearly show some corrosion of intraoral orthodontic components over time. The in vitro corrosion study by Grimsdottir and colleagues37 reported that nickel release from orthodontic metal appliances is most related to the solder composition and manufacturing of the appliances rather than being directly related to the actual nickel content. The study analyzed face bows, brackets, molar bands, and both stainless steel and nickel titanium arch wires for nickel release when stored in physiologic saline. The analysis indicated that appliances using silver and gold solders (eg, face bows and molar bands) showed enhanced release of nickel and chromium. In contrast, alloys containing titanium, for example arch wires, released little nickel when tested under the static conditions of this study. As noted by these studies, titanium has the advantage of being highly resistant to corrosion and may bind the nickel from release in these in vitro studies. What is unknown is what happens when friction of the arch wires in brackets might enhance the release of metal components from the appliances. Despite the research evidence to suggest otherwise, there have been several case reports of localized allergic responses credited to nickel-containing orthodontic appliances in the literature.41-46 Although each of these case reports is anecdotal and not conclusive to orthodontic appliances being the definitive causative agent, an associative link is a logical premise, given the individual presentations. The issue of possible nickel allergic responses in orthodontic patients is further expanded in terms of patient and clinician perspectives. In a survey of Norwegian orthodontists by Jacobsen and Hensten-Patterson,30 participants were asked to assess the number and nature of adverse reactions among their patients and to relate them to materials or treatment provided. The reactions reported were divided into dermal (extraoral) and intraoral/systemic reactions. Dermal reactions reported included redness, irritation, itching eczema, soreness, fissuring, and desquamation most often attributed to a metal extraoral (eg, headgear face bow) component of the appliances. Intraoral reactions included redness, swelling, itching and soreness of the lips and oral mucosa, and inflammation of the gingival tissues. Occasionally, symptoms such as fever, compatible with a general allergic reaction, were reported. Although not all the symptoms were attributed to the presence of metal components, they were assumed to be the primary allergens in these reported cases of hypersensitivity reactions.
Adverse hypersensitivity reactions In summary, the research literature suggests that metalbased orthodontic appliances do not increase the risk for nickel hypersensitivity to patients. Our current knowledge of intraoral orthodontic appliance corrosion patterns and the rare occurrence of possible nickel allergic responses in patients, even those with positive patch tests, suggests that concerns about sensitizing orthodontic patients to nickel are not supported in the literature. However, it would seem that caution and close monitoring should be exercised in patients with a defined history of atopic dermatitis to nickel-containing metals but that orthodontic treatment avoidance is unnecessary.
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