Allergic sensitization of the skin and oral mucosa to acrylic denture materials

[Chemical and physical properties of PMMA bone cements]

PMMA-based bone cements are used for anchoring artificial joints. The cements are offered as two-component systems. During mixing, a liquid paste is formed by free-radical polymerization, which completely hardens into a solid cement matrix as polymerization progresses with an increase in viscosity. Polymerization from MMA to PMMA is an exothermic process, energy is released in the form of heat. After fixation of the prosthesis and curing of the cement, the cement fills the space between the prosthesis and the bone. With the filler PMMA, a strong force-locking and interlocking mechanical bond is created. The essential properties of PMMA cements are dictated by the powder component. In vivo, the hard and brittle bone cements absorb body fluids and become more elastic and softer. The properties of various PMMA bone cements differ significantly, although the chemical acrylate base is identical.

Methacrylate perspective in current dental practice

OBJECTIVE

To provide a current perspective concerning dental personnel sensitivity to methacrylate materials.

OVERVIEW

Methacrylate related sensitivity and allergies are currently beyond traditional thoughts concerning denture base resins and methyl methacrylate provisional materials. Methacrylates are now ubiquitous in current dental practice and dental personnel should be aware that dental adhesives contain potent sensitizers that may also cross-sensitize individuals to other methacrylates not experienced. The growing sensitivity to 2-hydroxyethyl methacrylate (HEMA) has been described to be epidemic in nature due to the artificial nail industry with dental patients and dental personnel may be more susceptible to dental methacrylate sensitization. While contact dermatitis remains the most prevalent methacrylate-related clinical presentation, respiratory complications and asthma are increasing associated with methacrylate exposure. While additional personal protective equipment (PPE) is thought to be first protective choice, the National Institute for Occupational Safety and Health (NIOSH) considers PPE overall largely ineffective and should be considered only as a last resort.

CONCLUSION

Dental personnel need to be more aware of methacrylate sources and use workplace control measures to limit methacrylate exposures to both dental personnel and patients.

CLINICAL SIGNIFICANCE

Sensitivity to methacrylate materials is a growing dental workplace major concern and dental personnel should be aware of both the methacrylate content of current materials and the products that contain ingredients with the most sensitization potential.

The effects of the dental methacrylates TEGDMA, Bis-GMA, and UDMA on neutrophils in vitro

Objectives

The prevalent usage of methacrylates in modern dentistry demands good knowledge of their biological impacts. While there have been several studies demonstrating the effects of different methacrylic monomers on mononuclear white blood cells, very little is known about the effects caused by these monomers on neutrophilic granulocytes. The objective of this study was to add novel knowledge about how neutrophils are affected by exposure to triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), and bisphenol A glycol dimethacrylate (Bis‐GMA) alone or in combinations.

Materials and Methods

Isolated neutrophils were cultured in the presence or absence of methacrylates. The IL‐8 release was measured using a DuoSet ELISA development kit. Apoptosis and necrosis were analyzed using flow cytometry. The formation of neutrophil extracellular traps (NETs) was investigated using Sytox green DNA staining combined with microscopically examination of released DNA and myeloperoxidase (MPO).

Results

The release of IL‐8 was significantly increased after exposure to TEGDMA, Bis‐GMA, UDMA, or TEGDMA in combination with Bis‐GMA or UDMA compared to the unstimulated controls. Exposure to TEGDMA, UDMA, and Bis‐GMA for 24 hr separately or in combination did not affect apoptosis or necrosis of the exposed neutrophils. NET structures were formed by neutrophils after exposure to the different combinations of the methacrylates.

Conclusion

The combination of TEGDMA and Bis‐GMA had a synergistic proinflammatory effect on neutrophils by increasing the release of IL‐8 and the formation of NET structures. The changes in the normal functions of neutrophils caused by methacrylate exposure may lead to altered inflammatory response and relate to previously reported adverse immune reactions caused by these substances.

Triethylene glycol dimethacrylate: adjuvant properties and effect on cytokine production

Objective: Leakage of monomers from dental fillings due to incomplete curing is very common. The objective of the present study was to examine the cytokine profile in cells exposed to triethyleneglycol dimethacrylate (TEGDMA) and the adjuvant properties of TEGDMA.

Materials and methods: Human peripheral blood mononuclear cells were exposed to TEGDMA (500 and 1000 μM) for 24 h in vitro. Bio-Plex Pro™ assays were used for analysis and detection of cytokines. In vivo, BALB/c mice were immunized subcutaneously in the base of the tail with TEGDMA in combination with ovalbumin (OVA).

Results: The cytokine levels of IL-8, IL-18, GRO-α and MCP-1 were significantly increased for both concentrations. IL-1β, IL-6 and TNF-α was only significantly increased in cultures exposed to 500 μM TEGDMA. The concentration of TNF-α was significantly decreased in cultures exposed to 1000 μM TEGDMA. Animals immunized with OVA co-administrated with TEGDMA had a significantly higher IgE and IgG anti-OVA antibody levels in blood than animals immunized with OVA only.

Conclusions: TEGDMA affects production of proinflammatory cytokines IL-1β, IL-6, IL-8, IL-18 and TNF-α. This inflammatogenic capacity renders TEGDMAs adjuvant properties, which may interfere with the homeostasis between the immune system and the indigenous microflora in the oral cavity.

Ultrasonic cleaning reduces the residual monomer in acrylic resins

Background/purpose

The residual monomer remaining in acrylic resin can cause an allergic reaction and is toxic to oral soft tissue. This study determined the effect of the duration of ultrasonic cleaning on the amount of residual methyl methacrylate monomer in one heat-polymerized acrylic resin, Meliodent, and three autopolymerized acrylic resins, Unifast Trad Ivory, Unifast Trad Pink, and Unifast III.

Materials and methods

Thirty-six disc-shaped specimens of each brand were prepared and randomly divided into six groups: control (no treatment), positive control, and ultrasonic treatment in 50°C water for 3 minutes, 5 minutes, 10 minutes, or 15 minutes. The residual monomer was extracted and analyzed using high performance liquid chromatography.

Results

There were no significant differences in the residual monomer amount in the Meliodent groups. The amounts of residual monomer in the autopolymerized acrylic resin positive control group and ultrasonic treatment groups were significantly lower than those of the control group for the Unifast Trad Ivory, Unifast Trad Pink, and Unifast III groups (P < 0.05). The amount of residual monomer was not significantly different between the ultrasonic treatment in 50°C water (3 minutes for Unifast Trad Pink and 5 minutes for Unifast Trad Ivory and Unifast III) groups and the positive control group (P > 0.05).

Conclusion

Ultrasonic treatment with 50°C water for 3–5 minutes for autopolymerized resin and 3 minutes for heat-polymerized acrylic resin reduced the amount of residual monomer similarly to previously recommended methods, using shorter treatment times.

Description of a Rat Palatal Acrylic Plate That Can Be Relined

PURPOSE

The objective of this article is to describe a method to construct an intraoral acrylic device that permits a reline material to be added to the inner surface of the palatal plate.

MATERIALS AND METHODS

Fifteen 60-day-old adult female rats (Rattus Norvegicus Albinus Wistar), weighing 150 to 250 g were used for this study and allocated to three groups (n = 5): G1, animals wearing a heat-polymerized acrylic resin palatal plate (Lucitone 550) for 14 days; G2, animals wearing a heat-polymerized acrylic resin palatal plate (Lucitone 550) relined with Tokuyama Rebase II for 14 days; and G3, animals maintained under the same conditions as the experimental groups, without wearing palatal plates for 14 days. The manipulation of the animals followed the guidelines of the Brazilian College of Animal Experimentation, under the approval of the animal ethics committee of the State University of Ponta Grossa. The palatal plates covered the whole palate, were fixed in the molar region with light-cured resin, and were kept there for 14 days. The animals received a paste diet and water ad libitum. Before and after the trial period, the rats were weighed individually on a precision scale. Statistical analysis was performed using a two-way analysis of variance (α = 0.05) test for comparison of the animals' weight (g) at time 0 and after 14 days of using the palatal plate.

RESULTS

No statistical differences were observed regarding the weight of the animals among the experimental groups in the study.

CONCLUSIONS

The individual master impressions, the molar teeth coverage, and the method of cementation with nonadhesive composite resin provided good stability for the palatal plate showed in this study, not disturbing the eating habits and nutrition of the animals. This model seems reproducible, offering adequate histopathological evaluation. Differences in tissue morphology exist between the animals that used the palatal plate and the animals that did not use this device. Use of these palatal plates could clarify how prostheses bring changes in the palatal mucosa of users.

Comparative effect of different polymerization techniques on residual monomer and hardness properties of PMMA-based denture resins

PURPOSE

The aim of this study was to compare the residual monomer and microhardness of poly(methyl methacrylate) (PMMA)-based denture resins processed by using autoclave and conventional water bath techniques.

METHODS

To determine the amount of residual methyl methacrylate (MMA) monomer, disk-shaped specimens (n=5) were prepared from 3 different acrylic resins (Meliodent, Paladent and Qc-20). Control groups were polymerized in water bath for 30 minutes at 100°C. The study groups were prepared in an autoclave device for 60°C/30 min followed 130°C/10 min and the other group for 60°C/30 min followed by 130°C/20 min. According to standard calibration curves, ultraviolet spectrophotometry at 230 nm was used to determine the residual monomer. For the Vickers hardness measurements, disk-shaped specimens (n=5) were prepared for each test group. Hardness measurements were performed with a Vickers hardness tester under a 4.91-N press load for a 30 seconds, after immersion in distilled water at 37ºC for 48 hours. The data were analyzed by ANOVA and Tukey HSD test (p<0.05).

RESULTS

Autoclave polymerization produced a significant decrease in the amount of residual monomers for all resin groups (p<0.05). This procedure also showed a significant increase in hardness for all resin groups (p<0.05). For the 3 resin groups, no significant differences were found between autoclave polymerization for 10 minutes and for 20 minutes (p>0.05).

CONCLUSIONS

The autoclave polymerization technique exhibited significantly lower residual monomer content and greater hardness than conventional heat polymerization.

[Serious adverse events after microbial sealant application in paediatric patients]

BACKGROUND

Integuseal(®) is a cyanoacrylate-based medical device (IIa class), used in surgery after skin preparation to reduce bacterial contamination. It is not officially contraindicated for children.

OBJECTIVES

To describe a case series of skin lesions in pediatric patients after using Integuseal(®) in cardiac surgery.

METHODS

Case series.

RESULTS

Between September 2012 and February 2013, 153 pediatric patients were treated by Integuseal(®) to prepare for a cardiac surgery in our center: 5 patients (2%) had serious cutaneous reactions. The average age of patients having had lesions is 16months (the youngest patient being 1month old and the oldest being 5years and 8months old).

ISSUES

The risk factor in the development of skin lesion seems to be particularly related to the patient's age and sternal location. Other medical literature reports instances of cyanoacrylate intolerance in a variety of other situations.

CONCLUSION

Using Integuseal(®) on children does not appear to be safe.

Methyl methacrylate levels in orthopedic surgery: comparison of two conventional vacuum mixing systems

Poly-methyl methacrylate bone cements contain methyl methacrylate (MMA), which is known for its sensitizing and toxic properties. Therefore, in most European countries and in the USA, guidelines or regulations exist for occupational exposures. The use of vacuum mixing systems can significantly reduce airborne MMA concentrations during bone setting. Our goal was to test two commonly used vacuum mixing systems (Palamix(®) and Optivac(®)) using Palacos(®) R bone cement for their effectiveness at preventing MMA vapor release in a series of standardized trials in a laboratory as well as in an operating theatre. MMA was quantified every second over a period of 3 min using a photoionization detector (MiniRAE(®) 3000) device positioned in the breathing area of the user. Significant differences in MMA mean vapor concentrations over 180 s were observed in the two experimental spaces, with the highest mean concentrations (7.61 and 7.98 ppm for Palamix(®) and Optivac(®), respectively) observed in a laboratory with nine air changes per hour and the lowest average concentrations (1.06 and 1.12 ppm for Palamix(®) and Optivac(®), respectively) in an operating theatre with laminar flow ventilation and 22 air changes per hour. No significant differences in overall MMA concentrations were found between the two vacuum mixing systems in either location. Though, differences were found between both systems during single mixing phases. Thus, typical handling of MMA in orthopedic procedures must be seen as not harmful as concentrations do not reach the short-term exposure limit of 100 ppm. Additionally, laminar airflow seems to have an influence on lowering MMA concentrations in operation theatres.

An in vitro investigation into the cytotoxicity of methyl methacrylate monomer

Aim of this study was to assess the cytotoxicity of monomer. An in vitro study was designed to study the growth inhibitory effect of monomer (Stellon, Denture Material Improved, Type I, Class I, Dental Products of India Limited) on cells seeded in petri dishes and maintained in an incubator with 5% carbon dioxide at 37 °C. The growth of V79 cells (fibroblast cells) maintained in a culture medium to which monomer was added was studied for a period of 5 days. Results of this study pointed out that even at a concentration of 1 µl of monomer, the cell growth was significantly inhibited, when compared to the control group. The number of viable cells decreased dramatically whereas dead cells increased in the culture groups treated with the monomer. The cytotoxic effect was dose dependent. As the concentration increased from 1 to 10 µl there was a marked inhibition of cell growth and a corresponding increase in dead cell count. Results of this study proved beyond doubt that monomer is indeed cytotoxic even in very low concentrations. Thus, it becomes imperative to adopt every possible means to minimize residual monomer content in heat cured resins. Also precautions to minimize tissue contact should be taken while handling monomer by the dentist and dental personnel in the laboratory.

Allergic patch test reactions associated with cosmetics: retrospective analysis of cross-sectional data from the North American Contact Dermatitis Group, 2001-2004

BACKGROUND

Allergy to cosmetics is common.

OBJECTIVES

We sought to characterize patients with positive patch test reactions associated with a cosmetic source, to identify common allergens; and to explore gender and occupational associations.

METHODS

We performed a retrospective, cross-sectional analysis.

RESULTS

Of 6621 female and 3440 male patients, 1582 female (23.8%) and 611 of male (17.8%) patients had at least one allergic patch test reaction associated with a cosmetic source. Of "allergic" patients (>1 allergic reaction, n = 6815), females were 1.21 times more likely to have an allergic reaction associated with a cosmetic source than were male patients (p < .0001, 95% confidence interval [CI] 1.12-1.31). Within the "cosmetic allergic" group (n = 2243), head and neck involvement was significantly higher in female than in male patients (49.3% vs 23.7%, p < .0001). One hundred twenty-five patients had occupationally related allergic reactions associated with a cosmetic.

LIMITATIONS

This study is limited by its cross-sectional, retrospective design.

CONCLUSION

Of all patients studied, 21.8% had an allergic reaction associated with a cosmetic. Site of dermatitis, cosmetic categories, and specific allergens differed somewhat by gender.

Influence of Novel Resin Monomer on Viability of L-929 Mouse Fibroblasts in vitro

We have previously synthesized a novel acrylic resin monomer, methacryloyloxyethyl methyl succinate (TA). The aim of this in vitro study, therefore, was to examine its influence on cell viability using L-929 mouse fibroblasts and then compare the results with MMA, EMA, and LMA. Medium containing each monomer was changed every 15 minutes as some monomers were volatile. After one hour of exposure, these mediums were replaced with a normal medium and cells were further incubated for 72 hours. IC50 value for each monomer was determined, and chronological cell viability and cytomorphologic observation were evaluated. Viability was impaired in a dose-dependent manner. All monomers, except TA, tended to correlate between molecular weight and cell viability. On the other hand, TA showed excellent viability and did not impair growth abruptly. These results thus demonstrated that cellular damage by TA was much lower than that by other monomers.

The development and course of patch-test reactions to 2-hydroxyethyl methacrylate and ethyleneglycol dimethacrylate

Because Methacrylic monomers are used in dental work, dental personnel, technicians, and patients are at risk of being sensitized. 2-hydroxyethyl methacrylate (2-HEMA) and ethyleneglycol dimethacrylate (EGDMA) are commonly used. Allergic test reactions to them sometimes appear beyond D7. This study was designed to study the development and course of positive test reactions to 2-HEMA and EGDMA in allergic patients as a mean to elucidate the issue of patch-test sensitization. 12 patients with contact allergy to 2-HEMA and EGDMA were retested with dilution series. The clinical course was followed for 1 month. During the study, 25 positive test reactions to 2-HEMA and 19 to EGDMA were diagnosed. Within the 1st week, 21 were noted for 2-HEMA and 18 for EGDMA. After 10 days, another 2 reactions appeared for 2-HEMA and 1 for EGDMA. All but 1 patient with the latter reactions also had positive reactions within the 1st week. After 1 month, 12 reactions for 2-HEMA and 10 for EGDMA remained. Patch-test reactions to 2-HEMA and EGDMA are long-lasting. The patch-test concentrations of 2.0% for 2-HEMA and EGDMA may be continually used. Positive test reactions emerging after 10 days do not automatically imply active sensitization.

Use of a light-polymerized composite removable partial denture base for a patient hypersensitive to poly(methyl methacrylate), polysulfone, and polycarbonate: a clinical report

This article describes a light-polymerized composite denture base used for a patient with hypersensitivity to poly(methyl methacrylate) (PMMA), polysulfone (PSF), and polycarbonate (PC). A urethane-dimethacrylate (UDMA) composite was used as an alternative to fabricate both the denture base and the custom artificial teeth. Immediately after placing the new prosthesis, allergic symptoms disappeared from the patient's mucous membrane. The denture has functioned satisfactorily for more than 2.5 years without recurrence of the hypersensitivity.

A method for measuring the potential dermal exposure to methyl methacrylate during two different dental technical work tasks

Dental technicians are exposed on a daily basis to undiluted methyl methacrylate (MMA) when performing various routine tasks. Although the clinical effects of this chemical have been known for decades, no previous studies have been performed to estimate the potential dermal exposure to it. In this study we describe a patch-sampling technique to intercept the MMA that would otherwise have contaminated the skin on different parts of the hand and lower arm. Two different work tasks, making an orthodontic splint and denture preparation, were both performed under simulated workplace conditions twice by two recent graduated dental technicians. Air measurements were collected simultaneously. The results indicate that the exposure patterns associated with producing an orthodontic splint and denture preparation differed. We found work task-dependent differences in the amounts of MMA collected at the different parts of each hand, and differences between the right and left hands. There was also an interaction between hand and work task, especially for the right hand. The air measurements were positively correlated with the dermal exposure. This study highlights the importance of using a measurement strategy that takes the variability within the hand/arm body parts into account when measuring potential exposure during these kinds of work tasks. In order to establish future dermal exposure limits, more workplace and experimental studies are required.

Assessment of genetic damage by methyl methacrylate employing in vitro mammalian test system

Methyl methacrylate (MMA) is a volatile liquid widely used in the manufacture of acrylic polymers. In modern dentistry, MMA is the mainstream material in denture bases. MMA has been implicated as primary irritant and sensitizer, which can cause allergic eczematous reaction on the oral mucosa as well as skin. To date, there is growing concern that MMA may produce genetic damage by inducing mutation. In this study, colony forming efficiency, DNA synthesis, and cytogenetic assays were performed to investigate the adverse effects of MMA in cultured CHO cells. MMA was found to decrease colony formation in a dose- and time-dependent manner (P<0.05). MMA also inhibited DNA synthesis in a dose-dependent manner (P<0.05). The chromosome aberrations induced by MMA were the chromatid-type aberrations in the treated cultures. Moreover, the gaps and breaks were the most common type of aberrations observed. The sister-chromatid exchange frequencies were found to increase in the concentration of MMA. In this study, MMA was found to be not only a cytotoxic agent but also a genotoxic agent. The effects observed following treatment with low dose for longer duration is of relevance to the condition of the oral mucosa of the denture wears. Denture base resin could constantly release MMA extended periods, possibly causing moderate toxic reactions and possibly contributing to adverse effects on the mucosa.

Denture sore mouth

The majority of the lesions associated with DSM are preventable and can be managed successfully by the dental professional. The hyperplastic tissue response seen in denture wearing patients generally requires surgical excision and follow-up. Health care providers should be encouraged to ask patients to remove their prostheses during a thorough examination of the oral tissues. In addition, patients should be asked about the fit and comfort of their dentures, and referred to their dental health care team for appropriate follow-up when required.

Contact stomatitis

Contact stomatitis is inflammation or pain of the oral mucosa due to both irritant and allergic substances. Irritants include heat, frictional trauma, and chemicals. Oral flavorings, preservatives, and dental materials are common allergens. Simplification of oral care and avoidance of contactants is the primary mode of therapy. Patch testing to a broad series of antigens may be required to identify specific causes of allergic contact stomatitis.

Allergic contact stomatitis caused by acrylic monomer in a denture

A 71-year-old edentulous man developed a severely painful red mouth at sites of contact with a new denture. Patch testing showed allergy to samples of the denture material and to 2-hydroxyethyl methacrylate. Patch testing to methyl methacrylate was negative. Prolonged boiling of the denture resulted in reversal of his symptoms and samples of this fully cured denture material produced negative patch tests. While allergy to acrylates is a rare cause of stomatitis, this possibility must be considered in patients presenting with oral symptoms. Material safety data sheets are unreliable in providing information regarding the type of acrylate present in the material. Hence, patch testing should be performed with a battery of acrylate allergens as well as with small samples of the denture material.

Allergic contact gingivostomatitis from a temporary crown made of methacrylates and epoxy diacrylates

Occupational allergic contact dermatitis caused by (meth)acrylates is common in dental personnel, whereas dental acrylic fillings and crowns have rarely been reported to cause problems in dental patients. Here we report on a 48-year-old woman who developed gingivitis, stomatitis, and perioral dermatitis after a temporary crown made of restorative, two-component material had been inserted. The manufacturer stated that the temporary crown base paste and catalyst contained three (meth)acrylates, namely, a proacrylate, which is a modification of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (BIS-GMA); a tricyclate, which is a saturated, aliphatic, tricyclic methacrylate; and urethane methacrylate. The manufacturer refused to give more exact information on the (meth)acrylates. Patch testing revealed that the patient was highly allergic to BIS-GMA, other epoxy diacrylates, and (meth)acrylates, as well as to the base paste and catalyst of the temporary crown. Accordingly, it was concluded that the allergic reaction was caused by BIS-GMA, or a cross-reacting (meth)acrylate, or other (meth)acrylates in the temporary crown.

Component release from light-activated glass ionomer and compomer cements

The purpose of this study was to identify and quantify any component released from seven commercially available light-cured or resin-modified glass ionomer and compomer cements. Twenty-one separate cylindrical stainless steel moulds 6 mm in diameter and 1.0 mm deep were filled with one of seven glass ionomer or compomer cements, light activated and then immediately immersed in separate containers of distilled water. Water samples were retrieved over a time period of up to 30 days and retained for analysis. An occlusal cavity 6 mm in diameter was prepared in extracted human third molar teeth with a remaining dentin thickness of 1.6-2.0 mm. A polypropylene chamber was attached to the cemento-enamel junction of each tooth to contain 1 mL of distilled water. Ten teeth were each filled with one of three cements and light activated. Water samples (eluates) were retrieved over a period of time. All samples were analysed by high performance liquid chromatography. Only one component, hydroxyethyl methacrylate (HEMA), was detected in the eluates from both tooth and mould samples. Analysis of diffusion of the HEMA through dentin showed a relatively sustained movement into the pulp space during the first day, with exponential decline thereafter. Our data show that HEMA was released from all of the light activated glass ionomer cements studied and from the compomer, both directly into water and through dentin. This release may be relevant both to the risk of adverse pulpal responses in patients and to the risk of allergy in patients and dental personnel.

Management of embossment following the frontal osteoplastic operation

The deformity in the bony contour of the forehead following the osteoplastic flap procedure on the frontal sinus, termed embossment, occurs in a small but definite number of cases. This complication arises from the combined processes of resorption and deposition of bone following disturbance of the periosteum in performing the operation. A simple and highly reliable method of cosmetic correction employing acrylic cranioplasty has been successfully utilized in a series of cases without complications. The details of the operative technique will be outlined.

Bioavailability of components of resin-based materials which are applied to teeth

Chemical components of many materials used in dental practice can move into the local biophase, where they can have beneficial or adverse effects. The strongest indirect evidence that components of resin-based materials used in dentistry can move into the biophase are the many reports of allergic dermatitis in dental personnel. Direct measurement of component release has shown that triethylene glycol dimethacrylate (TEGDMA), hydroxyethyl methacrylate (HEMA), and, in the case of some orthodontic cements, bis-glycidyl methacrylate and benzoyl peroxide can move into an aqueous medium from a range of resin-based materials which are applied to teeth as part of oral care. In the case of resin composite restorations, HEMA and TEGDMA are available in microgram quantities via the salivary surface in the minutes and hours after clinical placement and via dentin and pulp in the hours and days after placement. Fortunately, moderate thickness of dentin protects pulp tissue against local toxicity. There are no data which suggest that systemic toxicity is a risk with any of these materials. There are some case reports of allergic responses to the monomers in patients, but the incidence of such responses appears at present to be much lower than that in dental personnel.

Evaluation of patch test results with denture material series

791 patients, among them 59 dental technicians and 732 other patients, were tested with the denture material series (DMS) recommended by the German Contact Dermatitis Research Group (DKG) in the hospitals of the Information Network of Departments of Dermatology (IVDK) between January 1990 and July 1993. Most frequently, positive reactions occurred to cadmium chloride in both groups. However, there was no evidence at all for relevance of these reactions. Benzoyl peroxide (BPO) ranked 2nd in patch test positivity. Although not statistically significant, reactions were more frequent in dental technicians, who might be exposed to BPO the in working environment. Methyl methacrylate (MMA) and triethylene glycol dimethacrylate (TEGDMA) were common sensitizers in dental technicians but not in other patients. This finding, too, has its explanation in the working process of manufacturing dental prostheses.

Occupational skin diseases in dental laboratory technicians. (I). Clinical picture and causative factors

In Germany, occupational skin disease (OSD) in dental technicians (DT) has been steadily rising in recent years and causing considerable costs for medical care and rehabilitation. Our objective in this study was to: (i) examine affected workers; (ii) perform patch tests to identify causative agents; (iii) develop strategies of prevention. 7 dental laboratories were inspected as to materials used, working habits, safety regulations, etc. A computer data base was developed for products (trade name, active ingredient, additives, etc.). A questionnaire regarding development of OSD was sent out to 1132 dental technicians (45 questions). 55 DT with suspected OSD were examined and patch tested with the standard series, an extensive series of methacrylates, and own materials. Working conditions, and knowledge of potential hazards, varied greatly in the laboratories visited. The safety data sheets of working materials were of little use and required supplementation by the computer data base, which provided rapid access to allergological information (e.g., type of acrylate, concentration). In the questionnaire (173 answers), 36% reported skin lesions attributed to work and 1/3 suspected plastic materials as their primary cause. Among the 55 DT examined, allergic contact dermatitis was diagnosed in 63.6% and irritant contact dermatitis in 23.6%. Most of the allergens identified (74%) were found in plastic materials (methyl methacrylate (MMA), 9 patients (16%); 2-hydroxyethyl methacrylate (2-HEMA), 18 patients (33%); ethyleneglycol dimethacrylate (EGDMA), 15 patients (27%)). In 16 patients, multiple sensitizations to various methacrylates were found. The fingertips were primarily involved in allergic contact dermatitis (93%), whereas in irritant contact dermatitis, the dorsa of the fingers (especially of the dominant hand) were affected (80%). 9 patients also showed lesions on the face, neck and forearms. The main irritant factors included wet work, contact with plaster, mechanical friction and thermal changes. Based on experience with DT, various preventive measures have been tried and found to be effective (reduction of skin contact, 4H Gloves, etc.). In conclusion, better knowledge of OSD in dental laboratories (in physicians, DT and their employers) would lead to a reduced rate of new cases.

Adverse contact reactions to sculptured acrylic nails: 4 case reports and a literature review

4 cases with differing presentations of contact allergy to acrylates in sculptured acrylic nails are presented. These reactions include nail fold, fingertip and hand dermatitis, face and neck dermatitis, dystrophic nail changes and paraesthesia. We discuss acrylic nails and review the previously published reactions to acrylates in acrylic nails.

Skin problems among Danish dental technicians. A cross-sectional study

Our objective was to evaluate changes in the prevalence of skin problems on the hands among dental technicians during the last 10 years by comparison with results of a previous study, to study whether the presence and location of skin problems could be related to work with acrylates, and to study whether the use of gloves had any influence on the prevalence of the skin problems. A cross-sectional questionnaire study among 192 dental technicians at work was performed using an expanded version of a questionnaire from a Danish survey 10 years ago. The cumulative prevalence of skin problems on the hands was 53%. The 1-year prevalence of skin problems on the hands was 43%. The point prevalence of skin problems on the hands was 36%. These prevalence figures were profoundly higher than the figures reported for the general population, and the figures did not differ from those obtained in the study 10 years ago. The point prevalence of skin problems on the hands among individuals handling acrylates was 38% higher than among individuals who never worked with acrylates. No difference in the occurrence of skin problems was observed between individuals using gloves and individuals who did not use gloves while handling acrylates. The prevalence difference of skin problems on the fingertips was 7.3% between individuals handling acrylates daily or several times a week and individuals handling acrylates less frequently.(ABSTRACT TRUNCATED AT 250 WORDS)

Occupational allergic contact dermatitis caused by exposure to acrylates during work with dental prostheses

Between 1974 and 1992, we were consulted by 4 patients (an orthodontist, 2 dental technicians and a dental worker trained in-house) who had developed occupational allergic contact dermatitis from working with dental prostheses. All patients had positive allergic patch test reactions to methyl methacrylate (MMA), the acrylate which is the most widely used in work with prostheses. All but the orthodontist also reacted to dimethacrylates, which are used in cross-linked dental prostheses. The last patient, investigated in 1992, had been exposed mainly to light-cured acrylics, which are similar in composition to dental composite resins. These acrylics, only recently introduced into prosthetic work, contain more potent acrylic sensitizers than MMA. Accordingly, dental personnel working with prostheses may face a higher risk of sensitization than previously. To detect cases of occupational allergic contact dermatitis, we suggest that patients working with dental prostheses should be patch tested with MMA, 2-hydroxyethyl methacrylate, dimethacrylates, epoxy acrylates and urethane acrylates.

Effect of the curing cycle on residual monomer levels of acrylic resin denture base polymers

It has been shown previously that high levels of residual monomer have a deleterious effect on the properties of denture base polymers. Levels of residual monomer were determined on a homopolymer and a copolymer using gas-liquid chromatography. A wide range of recommended and 'short cut' curing cycles were then investigated which produced values ranging from 0.56 to 18.46%. From the ranges examined an optimum cycle of 7 h at 70 degrees C and 1 h at 100 degrees C was established which was used to polymerize 23 currently available synthetic denture base polymers. Only small differences were found between the materials tested with a range from 0.54 to 1.08% of residual monomer.

Occupational contact dermatitis due to acrylonitrile

Within DSM Chemicals BV, a producer of acrylonitrile, skin complaints are frequent. The majority of these are of an irritant nature, while a smaller portion is based on acquired allergies. Allergological examination revealed 5 employees with an allergy to acrylonitrile. 1 of these subjects also developed paraesthesiae in the skin sites affected, a finding not previously described for acrylonitrile. In the guinea pig maximization test (GPMT), acrylonitrile showed strong allergenic potential. For prevention and treatment of contact allergologic disorders, close cooperation between occupational health officer, dermatologist and toxicologist in chemical companies is recommended.

A method of determining residual monomer in acrylic resin using methyl ethyl ketone

An improved method of extraction of residual monomer from acrylic resin has been described for determination of the concentration of residual monomer by gas chromatography. Four kinds of organic solvent selected according to their physicochemical properties (methanol, N,N-dimethylformamide, ethyl acetate and methyl ethyl ketone) were tested for their capacity to extract residual monomer at varying temperatures and time periods. Extraction with methyl ethyl ketone at 4 degrees C was found to be the most effective. The method is simpler and more effective than others reported so far, and therefore seems to be suitable for clinical laboratory use.

Laser-induced damage to transparent polymers: chemical effect of short-pulsed (Q-switched) Nd:YAG laser radiation on ophthalmic acrylic biomaterials. I. A review

The use of short-pulsed lasers in ophthalmic surgery inspired and called for research on the damage inflicted by the laser radiation upon the acrylic polymers from which artificial intraocular lenses are made. The possible release of toxic monomers by laser-induced depolymerization is of great concern but past investigations of this phenomenon have been very limited. The present knowledge of various types of laser-induced damage to transparent polymers is reviewed with particular emphasis on the acrylic materials and intraocular lenses.

Panels of allergens for specific occupations

It is important to have available panels of materials for patch testing patients working in specific occupations. Although it is not essential in every case to test with each substance listed on a given panel, careful consideration of the patient's work environment should suggest the specific test items that will provide the highest diagnostic yield in cases of allergic contact dermatitis.