High-quality acrylic fibers from waste textiles

The objective of this work is to develop a closed-loop recycling method specifically tailored for acrylic fibers. Recycling waste acrylic is essential, given the vast volumes of acrylic-containing textiles produced yearly and the strong capability of acrylics to generate toxic microplastics. However, none of the available closed-loop recycling, mechanical recycling, chemical recycling, and direct extrusion technologies work for acrylics. Acrylic fibers are always blended with other textile fibers, making fiber separation via mechanical recycling almost impossible. Polyacrylonitrile, an addition-polymerized thermoplastic material, cannot be depolymerized into its original monomer. Direct extrusion of waste acrylics faces issues of uncontrollable colors on fibers and pollution of spinning lines due to the influence of existing colorants. In our method, acrylic fibers were extracted from waste textiles using a novel approach involving maximized acrylic swelling and dissolution with dimethyl sulfoxide and butanediol. Cationic dyes were effectively removed through cost-effective recycling technology. This work demonstrates that cationic dyes seriously affect the acrylic dissolution, color consistency, and dyeability of regenerated fibers via direct wet extrusion. Such negative impacts of dyes have been eliminated by our cost-effective and closed-loop acrylic recycling technology, which enables the efficient separation of non-acrylic fibers and dyes from acrylic fibers. Our recycling system achieved zero discharges through recycling solvents, dyes, and acrylics. The regenerated acrylic fibers exhibited mechanical properties and dyeability comparable to virgin acrylic fibers. The material and energy costs to produce pure acrylic from waste textiles were only 40 % of those from fossils. This study successfully introduces a closed-loop recycling method for acrylic fibers from waste textiles, addressing key challenges in acrylic fiber recycling. Further research and implementation of this technology are recommended to advance its commercial viability and widespread adoption.

Dichloromethane-Induced Poisoning from Acrylic Paint Cleaner - Shenzhen City, Guangdong Province, China, 2023

What is already known about this topic?

Dichloromethane (DCM) is a colorless and transparent organic solvent that commonly causes poisoning during occupational contact.

What is added by this report?

Unknown to teachers and students, they were utilizing an acrylic paint cleaner that contained DCM. At the time of the poisoning incident, the art room was occupied beyond its capacity with inadequate local ventilation. The primary cause of the incident was determined to be the students' inhalation of DCM during the cleaning process.

What are the implications for public health practice?

The unclear composition of environmental cleaning products available for purchase online presents a major obstacle for consumers trying to assess their toxicity. It is imperative that robust regulatory measures and proactive public education campaigns are implemented to mitigate instances of poisoning.

Parametric and heat affected zone study on CO2 laser cutting of acrylic

Laser cutting is a non-contact machining employed for producing small, intricate shapes. The acrylic materials are widely used in many applications. The parametric and heat affected zone study of acrylic materials by using CO₂ laser machining is attempted in this research to evaluate the process variables, laser scanning speed, current, and nozzle-work material gap.•Research result indicate that the higher the current and the higher the cutting speed, result in higher the material removal rate•Other parameter such as current and nozzle, work material gap are also significant impact on the cutting process of the acrylic material.•In addition, heat affect zone increase with laser scanning speed.

Current and future trends in the teaching of removable partial dentures in dental schools in Malaysia: A cross sectional study

AIMS

To investigate, using a validated questionnaire, the teaching of removable partial dentures (RPDs) in dental schools of Malaysia.

MATERIALS AND METHODS

A validated questionnaire to investigating trends in the teaching of RPDs in dental schools in Oceania was emailed (in English version form) to Heads of Restorative/Prosthodontics/course coordinators in the 13 dental schools in Malaysia. Follow-up reminders were sent and participants were given six weeks to complete and return the questionnaire. Data was entered into an Excel spreadsheet and results compiled and analyzed.

RESULTS

Completed questionnaires were received from 13 dental school - a 100% response rate. All schools (n = 13) provided a preclinical technical course in RPD design. In most schools (n = 9, 69.2%), course work was supervised by senior lecturers while rest of the institutions made use of associate professor/professors. There were significant differences (p<0.05) between dental schools in terms of the contact hours dedicated to preclinical teaching. Students received an average of 62 h of instruction. Didactic instruction was the primary focus with practical (78 h) and didactic teaching (32 h). All dental schools (n = 13) provided practical surveyor design teaching (8 h). The staff student ratio for formal lectures (1:61), tutorials (1:29) and lab demonstrations (1:12) were recorded. Majority of the schools (n = 11, 84.6%) employed paired teaching in clinical sessions. All schools (n = 13, 100%) emphasized on increased teaching of RPD design and prescription writing in future clinical RPD courses.

CONCLUSION

Teaching of RPDs in Malaysia may be considered sufficient and comparable to the teaching in other parts of the world.

CLINICAL SIGNIFICANCE

Whilst the teaching of partial dentures at Dental Schools in Malaysia provides the core competencies involved in partial denture design and construction based on sound fundamental, scientific principles they should address the challenges of teaching partial dentures and other areas of dental education including improving working conditions for dental professionals.

Forensic examination of textile fibres using Raman imaging and multivariate analysis

Vibrational spectroscopic techniques have shown to be highly suitable for the identification and comparison of textile fibres and clothing fabrics. On the other hand, new chemical imaging modes based on these spectroscopic techniques are becoming useful in multiple fields. This is particularly important to, for instance, chemically visualize and screen different samples including forensic evidence (crime scene investigation), chemical and food products (quality control), biological tissues and living beings (medical imaging), among others. This study explores the forensic examination and selective chemical visualization of textile fibres and clothing fabrics using Raman imaging. Four experiments were performed, which were focused on the screening of (i) white different materials made of 100 % cotton (gauze, cotton wool, t-shirt, and swab), (ii) polyester and cotton fabrics evidence of the same colour, (iii) five different coloured cotton fabrics, and (iv) textile fibres of different materials (acrylic, cotton, nylon, polyester, and silk). Several methods of multivariate chemometric analysis including principal component analysis (PCA), multivariate analysis of variance (MANOVA), and multivariate curve resolution (MCR) were applied to enhance the limited visual comparison of the spectra accomplished with the unaided eye. The results evidenced the suitability of Raman imaging to statistically discriminate textile fibres and fabrics due to the chemical composition of both the clothing material and the dyestuff.

Intraocular Acrylic Allergy: Is it Something to Sneeze at?

Cataract surgery is most commonly performed with acrylic intraocular lens (IOL) implantation. To date, there have been no reported cases of intraocular acrylic allergy despite increasing rates of acrylic-induced contact dermatitis elsewhere in the body. Concern regarding acrylate sensitization is gaining traction in the ophthalmology community. This commentary explores the lack of intraocular atopy and whether an acrylic allergy necessitates extensive preoperative consideration.

Incidence of posterior capsule opacification following phacoemulsification in patients with uveitis

PURPOSE:

The purpose of this study was to evaluate the incidence of posterior capsule opacification (PCO) in patients with inactive uveitis who underwent phacoemulsification with acrylic hydrophobic intraocular lens.

METHODS:

Thus was a retrospective review of 25 consecutive patients (31 eyes) with uveitis who underwent phacoemulsification. A group of 100 patients (140 eyes) without uveitis served as historical controls.

RESULTS:

In patients with uveitis, PCO occurred in 11 eyes (35.5%), 6 (19%) of which were visually significant and required treatment with neodymium-doped yttrium aluminum garnet (Nd: YAG) laser. In the control group, PCO developed in 17 (12%) eyes which required treatment with Nd: YAG laser. The incidence of PCO was significantly higher in uveitis patients compared to the control group (P = 0.001), but the incidence of visually significant PCO requiring laser capsulotomy was not statistically significant (P = 0.3).

CONCLUSION:

The incidence of PCO in patients with uveitis was significantly higher than those without uveitis, but the need for Nd: YAG laser capsulotomy for visually significant PCO was not statistically significant.

Six-year clinical outcomes of implant-supported acrylic vs. ceramic superstructures according to the All-on-4 treatment concept for the rehabilitation of the edentulous maxilla

The aim of the current study was to document the long-term clinical results of the use of two prosthetic techniques for the rehabilitation of completely edentulous maxillae according to the “All-on-Four” concept: Fixed, screw-retained prosthesis mounted on a chrome-molybdenum framework with (1) metal-ceramic veneers and (2) Acrylic prosthesis with acrylic resin prosthetic teeth. A total of 34 patients were assigned to subgroups according to their own preference of the superstructure type (ceramics [n: 17] or acrylic resin [n: 17]). Prosthetic complications, marginal bone loss, plaque accumulation, bleeding on probing, bite force and oral-health-related quality of life were assessed over a period of 6 years. Marginal bone loss around implants of the ceramic group remained well within the limits for ‘success’, as defined by the 2007 Pisa consensus over the time (1.43 ± 0.35 mm). However, marginal bone loss was significantly more pronounced around the implants in the acrylic group (2.15 ± 0.30) and the difference between two groups was statistically significant (p: 0.00). Bleeding on probing and plaque accumulation showed also positive correlation with marginal bone loss. Both acrylic and ceramic suprastructures appeared to be equivalent after 6 years; however, ceramic suprastructures revealed superior clinical results in terms of bone loss and plaque accumulation. Current study determines the long-term clinical outcomes of different prosthetic management alternatives in All-on-Four and aids to increase dental professionals’ ability to meet the patients’ expectations.

Replication of the tensile behavior of knee ligaments using architected acrylic yarn

Knee ligament injury diagnosis is achieved by a comparison between the laxity levels sensed by a clinician in the injured and healthy limb. This is a difficult-to-learn task that requires hands-on practice to achieve proficiency. The inclusion of a physical knee simulator with biomechanically realistic passive components such as knee ligaments could provide consistent training for medical students and lead to improved care for knee injury patients. In this study, we developed a material construct that is both adaptable to a physical knee model and capable of replicating the non-linear mechanical behavior of knee ligaments with the use of helically arranged acrylic yarn. The microstructure of four different types of acrylic yarn were measured and then tested under uniaxial tension. While the fiber twist angle was similar amongst the four yarn types (range = 17.9-18.8°), one yarn was distinct with a low ply twist angle (15.2 ± 1.6°) and high packing fraction (Φ=0.32±0.08). These microstructural differences yielded a lower toe length and higher stiffness and best corresponded to ligament mechanical behavior. We then made looped-yarn constructs to modulate the sample's toe length and stiffness. We found that the load-displacement curve of the construct can be tuned by changing the loop length and loop number of the looped-yarn constructs, matching the load-displacement curve of specific knee ligaments. This study shows how spun yarn can be used to replicate the mechanical behavior of knee ligaments, creating synthetic ligament constructs that could enable the construction of biomechanically realistic joints.

Study on polymeric coatings on fly ash concrete under seawater

This study is focused on polymeric coatings on fly ash concrete submerged under seawater. The specimens were casted and coated with acrylic resin and epoxy resin of three layers each. The mechanical, durability, and microstructural properties of coated and uncoated fly ash concrete specimen were studied as pre- and post-exposed in seawater. Fly ash concrete coated with epoxy and acrylic had attained more strength compared to uncoated specimens. An increased strength in coated specimens and a decrease in value were observed in uncoated fly ash concrete specimens during split tensile strength. Coated specimens showed less reduction in pH value as compared to uncoated specimens. Rapid chloride permeability test (RCPT) analysis confirmed that epoxy and acrylic-coated concrete specimens appear to be denser than uncoated specimens leading to more resistance against the penetration of aggressive chemicals. The X-ray diffraction (XRD) comparative analysis of 56 and 90 days acrylic resin and epoxy resin-coated and uncoated specimen showed higher intensity in 90 days coated specimens than the uncoated specimens. Field emission scanning electron microscope (FESEM) investigation of uncoated 56 and 90 days concrete specimens subjected to seawater demonstrated dense appearance of hydrated products, whereas epoxy and acrylic-coated specimens were verified with no visible micro-cracks or holes on the surface, even at higher magnification. The epoxy and acrylic-coated fly ash concrete showed high physical strength and good bonding with concrete and will be appropriate for construction.

Improved methods for MRI-compatible implants in nonhuman primates

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We created custom PEEK implants coated with hydroxylapatite to promote osseointegration.

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Headposts and chambers were implanted with ceramic screws and the surgical incision was closed subcutaneously.

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We prevented the animal from picking and scratching after surgery by using a head cap that protects the wound margin.

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Implants integrated with the skull and remained robust after a year with no growth of granulation tissue.

•

MRI signal and contrast-to-noise ratio improved in NHPs implanted with our new methods.

Background

Neuroscientists commonly use permanently implanted headposts to stabilize the head of nonhuman primates (NHPs) during electrophysiology and functional magnetic resonance imaging (fMRI). Here, we present improved methodology for MRI-compatible implants without the use of acrylic for head stabilization in NHPs.

New method

MRI is used to obtain a 3D-reconstruction of NHP skulls, which are used to create customized implants by modeling intersections with the bone. Implants are manufactured from PEEK using computer numerical control machining and coated with hydroxyapatite to promote osseointegration. Surgically, implants are attached to the skull with ceramic screws, while the skin flap is pulled over the implant and closed subcutaneously.

Results

Quality of blood oxygen level dependent (BOLD) fMRI signal is improved in animals implanted with our method as compared to traditional acrylic implants. Additionally, implants are well-integrated with the skull, remain robust for more than a year and without granulation tissue around the skin margin.

Comparison with existing method(s)

Previous improvements on NHP implants (Chen et al., 2017; McAndrew et al., 2012; Mulliken et al., 2015; Overton et al., 2017) lacked fMRI-compatibility, as they relied on titanium headposts and/or titanium screws. Thus, most fMRI studies in NHPs today still rely on the use of acrylic-based headposts for stabilization and the use of contrast-enhanced agents to improve MRI signal.

Conclusions

Our method preserves fMRI-compatibility and results in measurable improvement in BOLD signal without the use of contrast-enhanced agents. Furthermore, the long-term stability of our implants contributes positively to the wellbeing of NHPs in neuroscience research.

Effect of Different Dentifrices on the Surface Roughness of Acrylic Resins: An in vitro Study

AIM

This study was undertaken to study the effect of three most commonly used dentifrices for denture cleaning and to find out any positive association between number of strokes by toothbrush and surface roughness of acrylic resin.

MATERIALS AND METHODS

About 40 acrylic rectangular blocks with high finish were polished until surface roughness was calculated as 0 pirn. The materials tested were distilled water as a control group, Patanjali Dant Kanti, Colgate Total Cream, and Cleansodent as dentifrices. Stroking was done with dentifrices, and surface roughness readings were recorded at 1,000, 9,000, and 18,000 strokes.

RESULTS

Patanjali Dant Kanti was found to have maximum abrasive potential followed by Colgate Total Cream, followed by Cleansodent and least by distilled water.

CONCLUSION

Surface roughness was found to be directly proportional to the type, size, and fineness of the abrasive component used; the professional denture cleanser (Cleansodent) has less abrasive potential than the regular toothpastes. Among those tested, the highest abrasive potential was found in Patanjali Dant Kanti and lowest by Cleansodent (denture cleanser).

CLINICAL SIGNIFICANCE

The patient as well as dentist should choose the dentifrice with utmost care noting the size and type of abrasives used. Washing the dentures normally with water without toothbrush daily and cleaning of dentures once in 10 to 15 days with a soft toothbrush and professional denture cleanser should be the line of maintenance of dentures.

Reversible opacification of hydrophobic acrylic intraocular lens- two cases report

Background

The opacification of the intraocular lens (IOL) can cause significant visual deterioration. It is known that opacity of hydrophobic acrylic IOLs is rare. We report 2 cases of reversible optic opacification of hydrophobic acrylic intraocular lenses (Tecnis ZCB00, Abbott), observed within 2 months after uneventful cataract surgery.

Case presentation

Case 1: Uneventful cataract surgery was performed on the left eye of an 86-year-old diabetic man with chronic open-angle glaucoma. A hydrophobic acrylic intraocular lens (IOL; Tecnis ZCB00, Abbott, Lake Bluff, IL) was implanted in the bag. Eye drops containing 0.5% levofloxacin and 1.0% prednisolone were used after surgery along with topical anti-glaucoma medications. At 7 weeks postoperative, cloudy, concentric IOL opacification developed, accompanied by decreased visual acuity and increased intraocular pressure. However, the opacification completely disappeared after 9 weeks.

Case 2: Uneventful cataract surgery was performed on the left eye of a 72-year-old woman. A hydrophobic acrylic IOL (Tecnis ZCB00) was implanted in the bag. At 2 weeks postoperative, cloudy, concentric IOL opacification developed, accompanied by ocular discomfort. After 4 weeks, opacification and discomfort completely disappeared.

Conclusions

We observed two cases of completely reversible opacification of hydrophobic acrylic IOLs. The exact nature of the transient opacity remains unclear, but an inflammatory origin cannot be completely ruled out.

Comparative study of visual function and ocular aberrations of two different one-piece designed hydrophilic acrylic intraocular lens

PURPOSE

To determine whether the aspherical IOL, Tecnis ZCB00, can improve the visual quality by measuring visual acuity, wavefront aberrations, and contrast sensitivity.

METHODS

It was a retrospective case series. Patients who underwent phacoemulsification cataract surgery were divided into two groups. One group (Group TC) was implanted with one-piece aspherical acrylic IOL (Tecnis ZCB00, AMO); the other (Group SA) was implanted with one-piece spherical acrylic IOL (Sensar AAB00, AMO). Eighty-eight eyes were selected into this study, among them 43 eyes in 26 male cases and 45 eyes in 29 female cases. Thirty-six eyes in 23 cases were in Group TC, and 52 eyes in 32 cases were in Group SA. Three months postoperatively, aberrations were analyzed with i-Trace visual function analyzer (Tracy Technologies, USA). Contrast sensitivities were measured with Takaci-CGT-1000 contrast glare tester (Seiko, Japan).

RESULTS

All the 88 eyes underwent phacoemulsification with intraocular lens implantation, without complications during or after surgery. Three months postoperatively, the uncorrected vision acuity in Group TC was significantly better than in Group SA (P = 0.007). At the pupil size of 5.0 mm, higher-order aberrations in Group TC were significantly higher than in Group SA (P = 0.02), especially the spherical aberration (Z ₄⁰ ) (P < 0.001); at the pupil size of 4.0 mm, Z ₄⁰ in Group SA was statistically higher than in Group TC (P < 0.001); at the pupil size of 3.0 mm, higher-order aberrations such as coma (Z ₃^-1,1 ) and trefoil aberration (Z ₃^-3,3 ) in Group SA were obviously higher than in Group TC (P = 0.01). In the low spatial frequency, the contrast sensitivity and the glare sensitivity in Group TC were significantly higher than in Group SA (P < 0.05).

CONCLUSIONS

By the short-term follow-up (3 months), the aspherical acrylic IOL can reduce the higher-order aberrations (especially the spherical aberration) and increase the contrast sensitivity to improve the visual performance.

The effectiveness of adhesives on the retention of mandibular free end saddle partial dentures: An in vitro study

OBJECTIVES

Existing in vitro methods for testing denture adhesives do not fully replicate the complex oral geometries and environment; and in vivo methods are qualitative, prone to bias and not easily reproducible. The purpose of this study was to develop a novel, quantitative and more accurate model to test the effect of adhesives on the retentive force of mandibular free end saddle partial dentures.

METHODS

An in vitro model was developed based on an anatomically accurate cast of a clinical case. Experimentally, the amount of adhesive was varied (0.2g-1g) and the tensile force required for displacement was measured. Different commercially available adhesives were then tested at the optimum volume using the in vitro model. A 3D finite element model of the denture was used to assess how the forces to induce denture displacement varied according to the position of the force along the saddle length.

RESULTS

The mass of adhesive was found to significantly alter retention forces, with 0.4-0.7g being the optimum range for this particular scenario. Use of adhesives significantly improved mandibular free end saddle partial denture retention with the worst performing adhesive increasing retention nine-fold whilst the best performing adhesive increased retention twenty three-fold. The finite element model revealed that 77% more force was required to displace the denture by positioning forces towards the mesial end of the saddle compared to the distal end.

CONCLUSIONS

An in vitro denture adhesive model was developed, which demonstrated that mass of adhesive plays a significant role in enhancing denture retention and supported the design principle of placing as few teeth as clinically necessary on the distal end of the free end saddles.

CLINICAL SIGNIFICANCE

Limiting the position of teeth on free end saddles to the mesial and mid portion of the saddle will reduce displacements caused by mastication. The movement of mandibular free end saddle partial dentures can be restricted with the use of denture adhesives. Altering the mass of adhesive used can further improve the retention of mandibular free end saddle partial dentures for patients.

Reinforcement of Aluminum Oxide Filler on the Flexural Strength of Different Types of Denture Base Resins: An In vitro Study

INTRODUCTION

Acrylic resins have been used extensively for the fabrication of denture bases because of their aesthetic qualities, ease of manipulation and repairability. Flexural fatigue of the denture base has been shown to be a factor in the clinical failure of polymethyl methacrylate resin dentures. Also, the fracture can result from impact, fatigue or degradation of the base material. Hence, there is a need to increase the strength of denture base resins.

AIM

To evaluate the effect of reinforcing alumina oxide filler on the flexural strength of different acrylic resins.

MATERIALS AND METHODS

A total of 180 acrylic specimens were fabricated, which were divided into three groups self cure acrylic resin (SC), conventional heat cure resin (HC) and high strength heat cure resin (HI). Each group was divided into four subgroups i.e., control group and the specimens of the remaining three groups were reinforced with aluminum oxide (Al2O3) powder by 5%, 10% and 15% by weight. Specimens were stored in distilled water for one week; flexural strength was tested by universal testing machine. Results were analysed by one-way analysis of variance and post-hoc Tukey paired group comparison tests.

RESULTS

Flexural strength of SC increased by 9%, 13% and 19%, Flexural strength of HC increased by 8%, 15% and 19% and that of HI increased by 21%, 26% and 29% compared to control group by adding 5%,10% and 15% of alumina filler (p-value <0.001). Addition of 15% of alumina powder to SC showed high flexure strength compared to control group of HC (p-value <0.001). Addition of 10% and 15% of alumina powder to HC showed high flexural strength compared to control group of HI (p-value <0.001).

CONCLUSION

Addition of alumina to self cure acrylic resin, conventional heat cure acrylic resin and high strength heat cure acrylic resin increased the flexural strength. Increasing the flexural strength of the acrylic resin base material could lead to more clinical success.

Canalization and maintaining the patency of external auditory canal in a congenital aural atresia patient: a multidisciplinary approach

This clinical report describes the role of a prosthodontist in rehabilitating a patient with congenital aural atresia. The external auditory canal and structure in the middle ear fail to develop completely in cases of congenital aural atresia. Canalization procedure to establish the communication between the external ear and middle ear, and maintaining the patency of the created canal plays an important role in the success of treatment in selected patients. Post Operative external auditory canal restenosis is the most common complication after congenital aural atresia surgery. The prosthodontist has an important role in assisting ENT surgeons in canalization procedure and also maintaining the patency of the canal during healing phase.

The impact of frenulum height on strains in maxillary denture bases

PURPOSE

The midline fracture of maxillary complete dentures is a frequently encountered complication. The purpose of this study was to assess the effect of frenulum height on midline strains of maxillary complete dentures.

MATERIALS AND METHODS

A removable maxillary complete denture was fabricated and duplicated seven times. Four different labial frenulum heights were tested for stresses occurring on the palatal cameo surface. The strains were measured with strain gauges placed on 5 different locations and the stresses were calculated. To mimic occlusal forces bilaterally 100 N of load was applied from the premolar and molar region.

RESULTS

A statistically significant association between the height of the labial frenulum and the calculated stresses and strains was shown (P<.05) predominantly on the midline and especially on the incisive papilla. The results showed that stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum.

CONCLUSION

Within the limitations of this in vitro study, it can be concluded that the stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. Surgical or mechanical precautions should be taken to prevent short-term failure of maxillary complete dentures due to stress concentration and low cycle fatigue tendency at the labial frenulum region.

The effect of Parylene coating on the surface roughness of PMMA after brushing

OBJECTIVES

Acrylic resins, used in the manufacturing of different types of intra-oral prostheses, are vulnerable to colonisation by microorganisms which potentially endanger the general health of the prostheses, wearers. The aim of this study was to investigate the influence of a novel coating (Parylene) on surface roughness of poly-methyl-methacrylate (PMMA) samples after simulated cleansing using an electric toothbrush and two brushing media (paste and pumice).

METHODS

Fifty-six square PMMA samples were fabricated. Half of the samples were coated with a uniform 10μm, coating of Parylene. All samples were subjected to simulated brushing with either paste or pumice. Changes in surface roughness were measured with a laser non-contact profilometer and compared between groups. Scanning electron microscopy (SEM) and Raman spectroscopy were utilised for surface visualisation and analysis.

RESULTS

In the coated samples, the mean surface roughness remained the same before and after brushing in the Paste group 2.69μm (SD=0.92 and SD=0.87 respectively), and increased from 3.73μm (SD=1.25) to, 5.05μm (SD=1.40) in the Pumice Group. In the uncoated samples, the mean surface roughness increased from 4.45μm (SD=0.92) to 6.73μm (SD=1.73) in the Paste group, and from 3.67μm (SD=0.74), to 7.50μm (SD=2.25) in the Pumice Group. Differences between the coated and uncoated groups were statistically significant (p<0.05). The surface analyses revealed that the coating remained adhered to the PMMA, although signs of partial detachment were noticed in the Pumice Group.

CONCLUSION

The Parylene coating resulted in a reduction of surface roughness of PMMA after brushing procedures.

CLINICAL SIGNIFICANCE

Parylene appears to maintain a low surface roughness of PMMA after abrasion by brushing.

Custom made acrylic tracheal stent for tracheal stenosis

The purpose of stenting for tracheal lesions varies from palliation, to cure, to stabilization while a reconstructive effort heals. This article describes a technique of fabricating customised acrylic tracheal stent for a patient with tracheal stenosis. Custom made acrylic tracheal stent described in this article facilitates easy manipulation during surgery and is cost effective when compared to pre fabricated silicone or other metallic stents.

Features and management of an acute allergic response to acrylic ocular prostheses

PURPOSE

To report the occurrence, causes and treatment of an acute allergic response to the acrylic resin used in ocular prostheses.

METHODS

Retrospective review of presenting history, clinical findings and treatment of two cases.

RESULTS

Both patients developed an acute onset hypersensitivity reaction thought to be due to the acrylic resin found in the ocular prosthesis. The first patient was successfully switched to a glass eye. The prosthesis of the second patient was treated with an extra long curing cycle, after which, the patient was able to tolerate their prosthesis with no complications.

CONCLUSION

The residual unpolymerized monomer that is present within poly-methylmethacrylate (PMMA) can rarely cause an allergic reaction. As an alternative to a glass eye the prosthesis may be subjected to an extended curing cycle converting more of the monomer to polymer.