Publications by authors named "Muhanad M Hatamleh"

33 Publications

Effect of freshly placed core buildup composites on setting of silicon impression materials.

J Indian Prosthodont Soc 2021 Apr-Jun;21(2):186-191

Department of Industrial Engineering, The University of Jordan, Amman, Jordan.

Aim: The aim is to study the effect of freshly placed composite build-ups on setting of additional silicone impression materials.

Settings And Design: In vitro - experimental study.

Materials And Methods: Three composite materials; Build-It™ F. R™, Filtek™ Bulk Fill flow and Filtek™ Z350 and three light-bodied additional silicone impression materials; Elite HD+, Aquasil LV Ultra and Express™ were used. Cylindrical-shaped specimens were made of each material (diameter 15 mm and height 10 mm). The silicone specimens were brought into contact with the composite specimens, which were either freshly cured (9 groups, n = 90) or cured and then stored in normal saline for 1 week (9 groups, n = 90). Shore A hardness (SAH) scores of silicone surfaces were recorded following the ASTM D2240-5 standards for shore A Durometer testing. Six measurements were made per each silicone surface and medians were calculated. Kruskal-Wallis and Mann-Whitney tests (SPSS v20) were used to check statistical significant differences between all groups and paired comparisons, respectively (P < 0.05).

Statistical Analysis Used: Kruskal-Wallis and Mann-Whitney tests.

Results: The SAH scores of additional silicones in direct contact with freshly placed composites were significantly less than SAH scores of additional silicones in direct contact with composites specimens aged for 1 week in 7 out of 9 combinations (P < 0.05). Only when Express™ and Elite HD+ were applied over freshly placed Filtek™ Bulk Fill flow, the SAH scores difference was not statistically significant to SAH scores of matching combinations applied after 1 week of composite storage.

Conclusions: Freshly placed composite might affect setting of additional silicone impression materials. Dentists should carefully assess final impression on areas of prepared teeth that have received composite fillings recently.
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http://dx.doi.org/10.4103/jips.jips_606_20DOI Listing
May 2021

Successful prosthetic salvage of a suboptimal autogenous auricular reconstruction with digital technologies: A report of 3 challenging treatments.

J Prosthet Dent 2021 Mar 29. Epub 2021 Mar 29.

Associate Professor, ENT department, Faculty of Medicine, Jordan University of Science and Technology, Irbid, Jordan.

The surgical reconstruction of congenitally missing or malformed ears is challenging and involves complicated surgeries. Ear shape, position, and skin color will likely be compromised in patients with relative anatomic symmetry, and it is easier to reproduce these features with a prosthesis. This article describes the prosthetic reconstruction of 3 patients who had received failed or suboptimal surgical reconstruction of their missing or deformed ears. Challenging characteristics included limited soft-tissue availability, skeletal hypoplasia with prominent concavity defect, and bilaterally missing ears with abnormally low hairline. Three-dimensional planning using a software program was used to determine the ideal implant locations and mirror the contralateral ear. The mirrored ear was 3-dimensionally printed with a stereolithography printer. The skin color was reproduced digitally by using the Spectromatch Pro system.
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http://dx.doi.org/10.1016/j.prosdent.2021.02.026DOI Listing
March 2021

Effect of universal adhesives on microtensile bond strength to hybrid ceramic.

BMC Oral Health 2019 08 6;19(1):178. Epub 2019 Aug 6.

Engineer Abdullah Bugshan research chair for Dental and Oral Rehabilitation, King Saud University, Riyadh, 11545, Saudi Arabia.

Background: The aim of this study was to evaluate the effect of universal adhesives (UA) and silane on the microtensile bond strength (μTBS) of resin cement to a hybrid ceramic Vita Enamic (VE).

Methods: VE specimens were acid etched using hydrofluoric acid (HF) and were assigned to three groups (n = 10) based on the applied bonding technique. In group 1 (S), a silane-based primer was used as a surface treatment prior to the application of a resin cement (Variolink Esthetic DC). In group 2, a silane-containing UA, Clearfil Universal Bond (CUB) was used for the surface treatment, and in group 3, A silane-free UA, Tetric N-Bond Universal (TNU) was used for surface treatment. Resin cement build-ups were prepared. The bonded specimens were sectioned into resin-ceramic beams. Half of the beams of each group were stored for 24 h at 37 °C and the other half were subjected to a thermo-cycling aging. The microtensile bond strength (μTBS) was measured at a crosshead speed of 0.5 mm/min. Failure modes were assessed accordingly. Data were analyzed using a) two-way analysis of variance ANOVA followed by one-way ANOVA and Tukey tests between groups and b) independent t-test to detect differences (α = 0.05) for each group. The surface topographies of the ceramic surface were evaluated using scanning electron microscopy.

Results: The results showed that silane-based primer (S) application resulted in significantly higher (p < 0.05) μTBS values after 24 h and after thermocycling compared to both silane-containing UA (CUB) and silane-free UA (TNU). The μTBS values of all groups were significantly reduced after thermocycling. No statistically significant difference was observed between the μTBS of CUB and TNU after 24 h. However, TNU showed significantly higher μTBS after thermocycling. Different failure modes were observed, and adhesive failure was the most common in all groups. Marked surface topographic changes were observed following HF etching.

Conclusion: It is concluded that, the UAs tested cannot be recommended as substitutes to the silanization of Hybrid ceramic.
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http://dx.doi.org/10.1186/s12903-019-0865-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6685274PMC
August 2019

Developing an In-house Interdisciplinary Three-Dimensional Service: Challenges, Benefits, and Innovative Health Care Solutions.

J Craniofac Surg 2018 Oct;29(7):1870-1875

Consultant Maxillofacial Surgeon, King's College Hospital NHS Foundation Trust, London, UK.

Three-dimensional printing (3DP) technologies have been employed in regular medical specialties. They span wide scope of uses, from creating 3D medical models to design and manufacture of Patient-specific implants and guidance devices which help to optimize medical treatments, patient education, and medical training. This article aims to provide an in-depth analysis of factors and aspects to consider when planning to setup a 3D service within a hospital serving various medical specialties. It will also describe challenges that might affect 3D service development and sustainability and describe representative cases that highlight some of the innovative approaches that are possible with 3D technology. Several companies can offer such 3DP service. They are often web based, time consuming, and requiring special call conference arrangements. Conversely, the establishment of in-house specialized hospital-based 3D services reduces the risks to personal information, while facilitating the development of local expertise in this technology. The establishment of a 3D facility requires careful consideration of multiple factors to enable the successful integration with existing services. These can be categorized under: planning, developing and sustaining 3D service; 3D service resources and networking workflow; resources and location; and 3D services quality and regulation management.
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http://dx.doi.org/10.1097/SCS.0000000000004743DOI Listing
October 2018

Surface characteristics and biocompatibility of cranioplasty titanium implants following different surface treatments.

Dent Mater 2018 Apr;34(4):676-683

University of Manchester, School of Medical Sciences and Photon Science Institute, JR Moore Building, Oxford Road, Manchester, M13 9PL, UK. Electronic address:

Objective: Surface and mechanical properties of titanium alloys are integral for their use in restoring bone defects of skull and face regions. These properties are affected by the method of constructing and surface treatment of the titanium implant. This study aimed to investigate the effects of titanium finishing protocols on the surface morphology, hardness and biocompatibility of TiAl6V4.

Methods: Square shaped TiAl6V4 specimens (ASTM F68) (10×10×0.5mm) were divided into seven groups of different surface treatments (n=10). The treatments included mechanical polishing, sandblasting with ALO (50μm), immersion in different acids, and/or electro-chemical anodization. Weight loss %; 3D micro-roughness; Knoop micro-hardness, and osteoblast cell attachment and proliferation (after 3 days) were determined for each specimen. Data was analysed using one way ANOVA and Dunett T3 post-hoc tests, and t-test (p<0.05).

Results: Weight loss % was in the range of 1.70-5.60 as mechanical polishing produced the highest weight loss, followed by sandblasting, and combined protocol of mechanical polishing and acid treatment (p<0.05). Micro-roughness values (μm) were in the range of 2.81-16.68. It was the highest for control specimens (p<0.05), and smoothest surfaces after combined mechanical polishing and acid treatment; or after electro-chemical treatment (p<0.05). Micro-hardness values (MPa) ranged 170.90-442.15 as sandblasting with/without acid treatment caused statically significantly the highest values (p<0.05) while control and mechanically polished specimens had the lowest values (p<0.05). All treatments produced equally biocompatible surfaces (p>0.05) after 1h or 3 days. Furthermore, osteoblast cell proliferation statistically significantly increased after 3days among each surface treatment (p<0.05).

Significance: Different finishing treatments have variable effect on cranioplasty titanium surface loss, micro-roughness and micro-hardness but constant improved biocompatibility effect. Electro-chemical treatment caused less material loss and produced biocompatible smoothest surface of comparable hardness; hence it can be suitable for cranioplasty titanium surface finishing.
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http://dx.doi.org/10.1016/j.dental.2018.01.016DOI Listing
April 2018

Fracture load and survival of anatomically representative monolithic lithium disilicate crowns with reduced tooth preparation and ceramic thickness.

J Adv Prosthodont 2017 Dec 14;9(6):416-422. Epub 2017 Dec 14.

School of Dentistry and Oral Health, Griffith University, Gold Coast, Australia.

Purpose: To investigate the effect of reducing tooth preparation and ceramic thickness on fracture resistance of lithium disilicate crowns.

Materials And Methods: Specimen preparation included a standard complete crown preparation of a typodont mandibular left first molar with an occlusal reduction of 2 mm, proximal/axial wall reduction of 1.5 mm, and 1.0 mm deep chamfer (Group A). Another typodont mandibular first molar was prepared with less tooth reduction: 1 mm occlusal and proximal/axial wall reduction and 0.8 mm chamfer (Group B). Twenty crowns were milled from each preparation corresponding to control group (n=5) and conditioned group of simultaneous thermal and mechanical loading in aqueous environment (n=15). All crowns were then loaded until fracture to determine the fracture load.

Results: The mean (SD) fracture load values (in Newton) for Group A were 2340 (83) and 2149 (649), and for Group B, 1752 (134) and 1054 (249) without and with fatigue, respectively. Reducing tooth preparation thickness significantly decreased fracture load of the crowns at baseline and after fatigue application. After fatigue, the mean fracture load statistically significantly decreased (<.001) in Group B; however, it was not affected (>.05) in Group A.

Conclusion: Reducing the amount of tooth preparation by 0.5 mm on the occlusal and proximal/axial wall with a 0.8 mm chamfer significantly reduced fracture load of the restoration. Tooth reduction required for lithium disilicate crowns is a crucial factor for a long-term successful application of this all-ceramic system.
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http://dx.doi.org/10.4047/jap.2017.9.6.416DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5741444PMC
December 2017

Survey of Ocular Prosthetics Rehabilitation in the United Kingdom, Part 2: Anophthalmic Patients' Satisfaction and Acceptance.

J Craniofac Surg 2017 Jul;28(5):1297-1301

*Department of Oral and Maxillofacial Surgery, King's College Hospital, London, UK †Faculty of Dentistry, Taibah University, Madina, Saudi Arabia ‡Department of Ocular Prosthetics, Manchester Royal Eye Hospital, Manchester, UK §Faculty of Medicine, Jordan University of Science and Technology, King Abdullah University Hospital, Irbid, Jordan ||Manchester Royal Eye Hospital, Manchester, UK.

Aim: Ocular prostheses are integral for anophthalmic patients. Part 1 of this study reported that patients' aetiology, opinions, and attitudes significantly affected their prosthetic eyes experience. Part 2 investigates the patient satisfaction and acceptance in light of some of the aetiological demographics reported in Part 1.

Methodology: One hundred sixty questionnaires were delivered to anophthalmic patients attending oculoplastic clinic. Etiological aspects presented in the questionnaire were disseminated in part 1. Patient satisfaction was assessed through 8 closed-end statements reflecting aspects concerning patient's views on prosthesis comfort and appearance; patient's expectations, self-esteem, and perception; and cooperation with ocularist. Each statement had 3 categories as agree, moderately agree, and disagree. A total of 126 questionnaires were returned (response rate was 78.8%). Data was analyzed using SPSS software. Association coefficients and correlations between variables were also analyzed.

Results: Total number of responses for the 8 statements was 888, averaging of 111 (expected 126) respondent per statement. Overall, 95.4% of our patients agreed with all satisfaction statements presented echoing very high satisfaction rate with their ocular prosthetics. Having an eye replacement that covers the defect is associated with high satisfaction among patients regardless of ocular prosthetic type. Patient acceptance of prosthesis in relation to employment status was high but not the same among the different categories (P > 0.05). High satisfaction with ocular prosthetics was prevalent among both genders, but there were no statistically significant differences in percentages of agreement in all statements (P > 0.05). Satisfaction and acceptance with ocular prosthetics was the same among all age groups of 12 to 85 years old (P > 0.05).

Conclusions: The patient satisfaction is associated with the interplay of different variables that is related to ocular prosthesis design and its ability to disguise disfigurement (ie, prosthesis shape, resemblance to existing contra-lateral eye, etc.); patients themselves (ie, gender, age, occupation, marital status, etc); and psychological well-being and social support provided. Anophthalmic patients of the north west of England are significantly happy with their ocular prosthetic rehabilitation and support they receive from their regional hospital. Ocular prosthetics enhances their psychological well-being and social interaction and factors like patients' sex, age, employment status, and type of ocular prosthesis have no effect on their acceptance and satisfaction.
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http://dx.doi.org/10.1097/SCS.0000000000003656DOI Listing
July 2017

Novel Treatment Planning of Hemimandibular Hyperplasia by the Use of Three-Dimensional Computer-Aided-Design and Computer-Aided-Manufacturing Technologies.

J Craniofac Surg 2017 May;28(3):764-767

*Cranio-Maxillofacial Prosthetics Unit, King's College Hospital NHS Foundation Trust †King's College Hospital NHS Foundation Trust, London, UK.

Rationale And Aim: Hemimandibular hyperplasia is characterized by an obvious overgrowth in the size of the mandible on one side, which can extend up to the midline causing facial asymmetry. Surgical resection of the overgrowth depends heavily on the skill and experience of the surgeon. This report describes a novel methodology of applying three-dimensional computer-aided-design and computer-aided-manufacturing principles in improving the outcome of surgery in 2 mandibular hyperplasia patients.

Methodology: Both patients had their cone beam computer tomography (CBCT) scan performed. CMF Pro Plan software (v. 2.1) was used to process the scan data into virtual 3-dimensional models of the maxilla and mandible. Head tilt was adjusted manually by following horizontal reference. Facial asymmetry secondary to mandibular hypertrophy was obvious on frontal and lateral views. Simulation functions were followed including mirror imaging of the unaffected mandibular side into the hyperplastic side and position was optimized by translation and orientation functions. Reconstruction of virtual symmetry was assessed and checked by running 3-dimensional measurements. Then, subtraction functions were used to create a 3-dimensional template defining the outline of the lower mandibular osteotomy needed. Precision of mandibular teeth was enhanced by amalgamating the CBCT scan with e-cast scan of the patient lower teeth. 3-Matic software (v. 10.0) was used in designing cutting guide(s) that define the amount of overgrowth to be resected. The top section of the guide was resting on the teeth hence ensuring stability and accuracy while positioning it. The guide design was exported as an .stl file and printed using in-house 3-dimensional printer in biocompatible resin.

Conclusion: Three-dimensional technologies of both softwares (CMF Pro Plan and 3-Matic) are accurate and reliable methods in the diagnosis, treatment planning, and designing of cutting guides that optimize surgical correction of hemimandibular hyperplasia at timely and cost-effect manner.
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http://dx.doi.org/10.1097/SCS.0000000000003438DOI Listing
May 2017

Survey of Ocular Prosthetics Rehabilitation in the United Kingdom, Part 1: Anophthalmic Patients' Aetiology, Opinions, and Attitudes.

J Craniofac Surg 2017 Jul;28(5):1293-1296

*Department of Oral and Maxillofacial Surgery, King's College Hospital, London †Department of Ocular Prosthetics, Manchester Royal Eye Hospital, Manchester, UK ‡Faculty of Medicine, Jordan University of Science and Technology, King Abdullah University Hospital, Irbid, Jordan §Manchester Royal Eye Hospital, Manchester, UK.

Purpose: Ocular prostheses are constructed to aid cosmetic, functional, and psychological rehabilitation of anophthalmic patients. Part-1 of this study aimed to evaluate anophthalmic patients' opinions, attitudes, and experience about aspects related to their postfit ocular prostheses.

Methods: One hundred sixty questionnaires were delivered to anophthalmic patients inquiring about different information such as age, gender, occupation, eye-loss cause, prosthesis type, prosthesis-wearing frequency, prosthesis-cleaning frequency, and problems encountered. A total of 126 questionnaires were returned (response rate was 78.8%). Data was analyzed using SPSS software (P <0.05).

Results: The patients were 74 males and 52 females (57.55 years ± 17.57). Almost 50% of the patients lost their eye due to trauma that was the highest among other causes (P <0.05). High proportion clean their prosthesis daily (37.4%) which was the highest among other cleaning regimes (P <0.05). Almost 30.3% experienced having problems with their prosthetic eye. Patients who clean their prosthetic eye every 6 months have experienced more problems (P <0.05). Majority of patients wear their prosthetic eyes 24 hours (92%) (P <0.05). Half of patients who received a prosthetic eye for the first time experienced problems with it (P <0.05) such as excess discharge (45%), infection (25%), and soreness (20%). However, the problems were independent of prosthesis-type (P >0.05).

Conclusions: Trauma is the most common cause of anophthalmic patients in the North-West of England. Anophthalmic patients are likely to experience problems with their prosthetic eye if they have lost their natural eye due to disease; it is their first prosthesis; or if they clean it once every 6 months.
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http://dx.doi.org/10.1097/SCS.0000000000003370DOI Listing
July 2017

Simultaneous Computer-Aided Design/Computer-Aided Manufacture Bimaxillary Orthognathic Surgery and Mandibular Reconstruction Using Selective-Laser Sintered Titanium Implant.

J Craniofac Surg 2016 Oct;27(7):1810-1814

*Reconstructive Science, Cranio-Maxillofacial Prosthetics Unit †Orthodontics ‡Maxillofacial Surgery §King's College Hospital NHS Foundation Trust, London, UK.

This patient report describes simultaneous bimaxillary orthognathic surgery and mandibular reconstruction by means of three-dimensional (3D) planning, 3D printed biocompatible surgical wafers, and 3D selective-laser sintered titanium implant. A 26-year-old male patient presented with a left mandibular defect secondary to trauma. The whole body of the mandible on the left hand side was deficient with a narrow connection with the remaining left condyle. He had undergone orthodontic treatment for 18 months and was ready to undergo bimaxillary orthognathic surgery. Advanced cranio-maxillofacial software was used in processing his cone beam computer tomography scan data, and e-casts of his upper and lower dental arches. Bimaxillary surgery was planned with Le Fort 1 maxillary impaction and mandibular advancement to achieve a class 1 incisor relationship. Intermediate and final surgical wafers were designed following the planned movements and printed using biocompatible resin. The deficient left side of the mandible was reconstructed by means of mirror imaging the contra-lateral right side into the deficient left side with the aim of restoring normal facial symmetry. Biomedical software was then used in designing a reconstruction plate that connected the condylar head and the mandible following the planned bimaxillary surgery and mandibular continuity symmetry reconstruction. The plate was printed in titanium following state-of the-art selective laser sintering technology. The bimaxillary surgery and mandibular reconstruction were done simultaneously as planned along with an iliac-crest bone graft. This patient confirms the advantages of 3D computer-aided design/computer-aided manufacture technologies in optimizing clinical outcomes for cranio-maxillofacial reconstruction, especially when conducting two simultaneous clinical procedures.
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http://dx.doi.org/10.1097/SCS.0000000000003039DOI Listing
October 2016

The Impact of Core/Veneer Thickness Ratio and Cyclic Loading on Fracture Resistance of Lithium Disilicate Crown.

J Prosthodont 2018 Jan 9;27(1):75-82. Epub 2016 Mar 9.

School of Dentistry and Oral Health, Griffith University, Queensland, Australia.

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http://dx.doi.org/10.1111/jopr.12473DOI Listing
January 2018

Mechanical Properties and Simulated Aging of Silicone Maxillofacial Elastomers: Advancements in the Past 45 Years.

J Prosthodont 2016 Jul 24;25(5):418-26. Epub 2016 Jan 24.

Department of Substitutive Dental Science, Faculty of Dentistry, Taibah University, Madinah, Saudi Arabia.

Purpose: To identify and discuss the findings of publications on mechanical behavior of maxillofacial prosthetic materials published since 1969.

Methods: Original experimental articles reporting on mechanical properties of maxillofacial prosthetic materials were included. A two-stage search of the literature, electronic and hand search, identified relevant published studies up to May 2015. An extensive electronic search was conducted of databases including PubMed, Embase, Scopus, and Google Scholar. Included primary studies (n = 63) reported on tensile strength, tear strength, and hardness of maxillofacial prosthetic materials at baseline and after aging.

Results: The search revealed 63 papers, with more than 28 papers being published in the past 10 years, which shows an increased number of publications when compared to only 6 papers published in the 1970s. The increase is linear with significant correlation (r = 0.85). Such an increase reflects great awareness and continued developments and warrants more research in the field of maxillofacial prosthetic materials properties; however, it is difficult to directly compare results, as studies varied in maxillofacial prosthetic materials tested with various silicone elastomers being heavily investigated, standards followed in preparing test specimens, experimental testing protocols, and parameters used in setting simulated aging conditionings.

Conclusion: It is imperative to overcome the existing variability by establishing unified national or international standards/specifications for maxillofacial prosthetic materials. Standardization organizations or bodies, the scientific community, and academia need to be coordinated to achieve this goal. In the meantime and despite all of these theoretically significant alternatives, clinical practice still faces problems with serviceability of maxillofacial prostheses.
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http://dx.doi.org/10.1111/jopr.12409DOI Listing
July 2016

Bond strength of self-adhesive resin cements to tooth structure.

Saudi Dent J 2015 Apr 28;27(2):70-4. Epub 2015 Jan 28.

Faculty of Dentistry, The University of Jordan, Amman 11942, Jordan.

Objectives: The aim of this study was to evaluate the strength of the bond between newly introduced self-adhesive resin cements and tooth structures (i.e., enamel and dentin).

Methods: Three self-adhesive cements (SmartCem2, RelyX Unicem, seT SDI) were tested. Cylindrical-shaped cement specimens (diameter, 3 mm; height, 3 mm) were bonded to enamel and dentin. Test specimens were incubated at 37 °C for 24 h. The shear bond strength (SBS) was tested in a Zwick Roll testing machine. Results were analyzed by one-way ANOVA and t-test. Statistically significant differences were defined at the α = 0.05 level. Bond failures were categorized as adhesive, cohesive, or mixed.

Results: The SBS values ranged from 3.76 to 6.81 MPa for cements bonded to enamel and from 4.48 to 5.94 MPa for cements bonded to dentin (p > 0.05 between surfaces). There were no statistically significant differences between the SBS values to enamel versus dentin for any given cement type. All cements exhibited adhesive failure at the resin/tooth interface.

Conclusions: Regardless of their clinical simplicity, the self-adhesive resin cements examined in this study exhibit limited bond performance to tooth structures; therefore, these cements must be used with caution.
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http://dx.doi.org/10.1016/j.sdentj.2014.11.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4459118PMC
April 2015

Closed-eye orbital prosthesis: a clinical report.

J Prosthet Dent 2015 Mar 20;113(3):246-9. Epub 2014 Nov 20.

Consultant maxillofacial surgeon, Maxillofacial Department, Queens Medical Centre, Nottingham University Hospital Trust, Nottingham, UK.

One of the most challenging prostheses to fabricate is an acceptable orbital prosthesis. Successful reconstruction of the complex missing tissues, the globe, muscle, skin, and bony elements requires time and high levels of practical skill. A good match to the contralateral nondefect side will help mask the underlying defect and give the patient confidence to return to normal, routine life. The contralateral eye opening will commonly dictate the eye opening of such a prosthesis, but because of the expressive nature of the eye and its high levels of mobility, this can be difficult to achieve. This clinical report presents a patient who had an extended orbital exenteration and right maxillectomy to remove a maxillary squamous cell carcinoma. An alternative approach to constructing an orbital prosthesis was undertaken with the eye closed. Compared to the normal method of fabrication, this process was less complex and quicker, made the prosthesis less "staring," camouflaged the defect, and reduced the detection of the prosthesis because of movements in the remaining eye. The patient engaged in his routine daily life, which reinforced his self-esteem, confidence, and reintegration into the community.
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http://dx.doi.org/10.1016/j.prosdent.2014.07.018DOI Listing
March 2015

Complete integration of technology for improved reproduction of auricular prostheses.

J Prosthet Dent 2014 May 17;111(5):430-6. Epub 2014 Jan 17.

Maxillofacial Prosthetist, Maxillofacial Department, Queens Medical Centre; and Lecturer, School of Dentistry, University of Manchester, Manchester, UK.

The accurate reproduction of the form and surface details of missing body structures is an essential part of any successful prosthetic rehabilitation. It helps mask the prosthesis and gives confidence to the patient. This clinical report details the integration of multiple in-house digital technologies of laser scanning, rapid prototyping, and digital color scanning and formulating to improve the shape, texture, orientation, and color of auricular prostheses for 3 patients with missing unilateral ears. A structured light laser scanner was used to digitize the patient's nondefect ear. The digitized data were then manipulated in specialist software and mirrored to reflect the opposing side. A rapid prototyping machine was used to manufacture a 3-dimensional (3D) model of the soft tissue required. This 3D mirrored ear model allowed the accurate reproduction of missing soft tissue. A color spectrometer was used to accurately reproduce the skin tones digitally and physically.
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http://dx.doi.org/10.1016/j.prosdent.2013.07.018DOI Listing
May 2014

A novel approach to immediate restoration of the cosmetic deformity after regional temporalis flap reconstruction of a maxillary defect: a case report.

J Craniofac Surg 2013 Nov;24(6):2186-9

From the *Faculty of Applied Medical Science, Jordan University of Science and Technology, Irbid, Jordan; and †Maxillofacial Department, Queens Medical Centre Campus, Nottingham University Hospital Trust, Nottingham, England.

Restoration of large maxillary defects can be achieved by using various muscle and bone flap transfers. Free muscle and bone transfer has become the reconstruction standard because it offers a combination of bone and soft tissues, which allows primary closure of the defect and secondary placement of dental implants for a full rehabilitation approach. If free tissue transfer is not a viable option, regional flaps such as temporalis muscle offer a viable alternative. This report presents a novel approach to immediate reconstruction of temporalis defects after muscle transfer to repair a maxillary defect. A custom-made titanium onlay was constructed preoperatively using a three-dimensional model of the patient to restore the absent muscle contour. The implant was placed at the same time as the muscle transfer. A good cosmetic outcome was achieved, and no postoperative complications were reported.
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http://dx.doi.org/10.1097/SCS.0b013e3182a41c7fDOI Listing
November 2013

Management of extensive frontal cranioplasty defects.

J Craniofac Surg 2013 Nov;24(6):2018-22

From the *Maxillofacial Unit, Maxillofacial Surgery, Queens Medical Centre Campus, Nottingham University Hospital, Nottingham, England; †Faculty of Applied Medical Science, Jordan University of Science and Technology, Irbid, Jordan; and ‡Neurosurgery Department, Queens Medical Centre Campus, Nottingham University Hospital Trust, Nottingham, England.

Cranioplasty is a medical technique to correct cranial bone defects. Depending on the size and location of the defect, a bone substitute can be used to replace the missing bone. Frontal bone defects are important to patients in terms of cosmetics because they are visible. Advances in computer design allow the production of customized implants with improved cosmetic and functional results. This report describes hybrid optimization of three-dimensional technological methods along with traditional methods toward the manufacture of deep-buried titanium implants, restoring frontal skull defects for 4 patients. A three-dimensional model was produced from the computed tomographic scan data of 3 patients using an in-house three-dimensional printer. A new approach was followed in treating the fourth patient. The defect was restored using preoperative scan before cranioplasty. These data were transported digitally into the defect skull to recreate the bone contour required, and a three-dimensional model was produced from the "new" digital model using the three-dimensional printer. Defect areas of the patients were large and measured 101.21 × 123.35 (vertical × horizontal) in average (mm). Conventional wax-up of the defect was carried to restore normal conformity. A titanium sheet (0.5 mm) was swaged into the desired shape; however, convexity of the defect area makes titanium swaging challenging, especially at the deep lateral undercuts. Making side flanges at reasonable lengths made it easy to swage without creasing. Three-dimensional models aided to produce accurately fitting plates. Finally, the sequential method of using both digital and manual procedures is a low-cost, reliable, accurate, and reproducible method.
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http://dx.doi.org/10.1097/SCS.0b013e3182a41bccDOI Listing
November 2013

Accuracy and reliability of methods to measure marginal adaptation of crowns and FDPs: a literature review.

J Prosthodont 2013 Jul 4;22(5):419-28. Epub 2013 Jan 4.

Griffith University, School of Dentistry and Oral Health, Gold Coast, Australi.

Purpose: To review methods used to investigate marginal adaptation of crowns and fixed dental prostheses (FDPs), and to discuss testing variables employed and their influence on results.

Methods: Online libraries including PubMed, Scopus, and Ovid were searched for articles evaluating the marginal adaptation of crowns and FDPs using a combination of the keywords: "marginal accuracy," "marginal fit," "marginal gap," "marginal discrepancy," "fitting accuracy," "crown," and "FPD." Peer-reviewed publications in English in the period 1970 to December 2011 were collected, evaluated by their abstract, and included if they met the inclusion criteria. The criteria involved studies evaluating marginal adaptation of crowns and FDPs through clear experimental protocols. Exclusion criteria involved longitudinal prospective and retrospective clinical evaluations, studies using subjective tactile sensation, and other predefined criteria.

Results: A total of 277 papers were identified; only 183 met the inclusion criteria. Direct view technique was used by 47.5% of the articles followed by cross-sectioning (23.5%), and impression replica (20.2%) techniques. The marginal gap values reported by these techniques varied among individual crown systems and across different systems because of variations in study type (in vivo vs. in vitro), sample size and measurements per specimen, finish line design, and stage at which the marginal gap was measured.

Conclusion: There was a substantial lack of consensus relating to marginal adaptation of various crown systems due to differences in testing methods and experimental protocols employed. Direct view technique was the most commonly used method of reproducible results. Also, conducting an experimental set-up of testing a minimum of 30 specimens at 50 measurements per specimen should produce reliable results. Additionally, using a combination of two measurement methods can be useful in verification of results.
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http://dx.doi.org/10.1111/jopr.12006DOI Listing
July 2013

Prosthetic eye rehabilitation and management of completely blind patients.

Int J Prosthodont 2012 Nov-Dec;25(6):631-5

Jordan University of Science and Technology, Irbid, Jordan.

Facial prostheses aim to restore the appearance, contours, and esthetics of the face while consequently enhancing patients' self-esteem and reintegration into social life. Restoring unilateral missing ocular and orbital tissues is a challenging task that requires great skill from the clinician (anaplastologist) to accurately mimic the opposing natural tissues. Bilateral defects present additional technical and clinical challenges for clinicians and patients alike. This article presents two cases involving restoration of the ocular and orbital components of bilaterally blind patients. The first case comprised the construction of indwelling scleral eye shells for both eyes, while the second comprised left orbital (implant-retained) and right indwelling eye shell prostheses. Custom-made bilaterally indwelling eyes are more esthetically pleasing than stock options and show better fit and comfort following conventional impression techniques. Clinical challenges include impression taking, prosthesis fabrication, identification of the correct orientation into the socket, communication with the patient, and satisfaction of patient expectations. Since both patients were blind, their families played a vital role in describing their prostheses and thus in improving the patients' self-esteem and satisfaction with treatment.
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January 2013

Fracture resistance of fixed partial dentures supported by different abutment combinations: an ex vivo study.

Gen Dent 2012 Sep-Oct;60(5):e295-301

Department of Fixed Prosthodontics, School of Dentistry, Jordan University of Science & Technology, Irbid, Jordan.

This study sought to compare the fracture resistance of and categorize failure modes exhibited by fixed partial dentures (FPDs) supported by natural teeth, implants, or mixed tooth-implant abutments. Three groups utilized three different abutment combinations: all natural teeth, all implants, and a mixture of teeth and implants. The teeth were prepared and zero-angled titanium abutments were installed over the implants. Standardized conventional three-unit porcelain-fused-to-metal FPDs were fabricated, following the conventional ceramic build-up technique. The inner surfaces of the bridges were air-abraded (50 μm Aluminum Oxide at 80 psi), cleaned in an ultrasonic bath for 10 minutes, and cemented over abutments using glass ionomer cement. The FPDs were fixed in a universal testing machine and compressed to fracture using a three-unit metal block at a 5 mm/minute crosshead speed. Fracture loads ranged from 460 to 5,700 N. Bridges supported by either implant abutments only or mixed implant-tooth abutments showed higher fracture loads (2,940 and 3,390 N, respectively) than those supported entirely by natural teeth (1,386 N) (p < 0.05). However, fracture of the veneering porcelain was common among all types of abutments.
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November 2013

Construction of an implant-retained auricular prosthesis with the aid of contemporary digital technologies: a clinical report.

J Prosthodont 2013 Feb 4;22(2):132-6. Epub 2012 Sep 4.

Faculty of Applied Medical Science, Jordan University of Science and Technology, Irbid, Jordan.

Implant-retained auricular prostheses are a successful treatment modality for children with microtia. They involve only minor surgical intervention of implant placement and result in an esthetically pleasing outcome. Integration of digital technologies (DT) in the prosthetic reconstruction process is a new approach toward enhancing outcomes. In this report we present a case of auricular prosthetic reconstruction following two implant placements in the right mastoid region. The ear prosthesis was constructed with the aid of various DTs. A structured light laser scanner was used to digitize the nondefect patient ear. The digitized 3D ear was then manipulated in specialist software, mirrored to reflect the opposing side, and a Rapid Prototyping (RP) machine (Z-Corp) was used to manufacture the soft tissue required. This RP-mirrored ear model allows very accurate reproduction to replicate missing soft tissue. A color Spectrometer was used to accurately reproduce skin tones. The use of these technologies is now routine practice at our unit. They enhance prosthetic outcomes and esthetics, save the prosthetist's time, and are digitally stored and subsequently readily available and reproducible.
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http://dx.doi.org/10.1111/j.1532-849X.2012.00916.xDOI Listing
February 2013

Effect of extraoral aging conditions on mechanical properties of maxillofacial silicone elastomer.

J Prosthodont 2011 Aug 20;20(6):439-46. Epub 2011 Jul 20.

Biomaterials Research Group, School of Dentistry, University of Manchester, Manchester, UK.

Purpose: The purpose of this study was to investigate the effect of extraoral human and environmental conditions on the mechanical properties (tensile strength and modulus, elongation, tear strength hardness) of maxillofacial silicone elastomer.

Materials And Methods: Specimens were fabricated using TechSil-S25 silicone elastomer (Technovent Ltd, Leeds, UK). Eight groups were prepared (21 specimens in each group; eight tensile, eight tear, five hardness) and conditioned differently as follows (groups 1 through 8): Dry storage for 24 hours; dry storage in dark for 6 months; storage in simulated sebum solution for 6 months; storage in simulated acidic perspiration for 6 months; accelerated artificial daylight aging under controlled moisture for 360 hours; outdoor weathering for 6 months; storage in antimicrobial silicone-cleaning solution for 30 hours; and mixed conditioning of sebum storage and light aging for 360 hours. The conditioning period selected simulated a prosthesis being in service for up to 12 months. Tensile and tear test specimens were fabricated and tested according to the International Standards Organization (ISO) standards no. 37 and 34, respectively. Shore A hardness test specimens were fabricated and tested according to the American Standards for Testing and Materials (ASTM) D 2240. Data were analyzed with one-way ANOVA, Bonferroni, and Dunnett's T3 post hoc tests (p < 0.05). Weibull analysis was also used for tensile strength and tear strength.

Results: Statistically significant differences were evident among all properties tested. Mixed conditioning of simulated sebum storage under accelerated artificial daylight aging significantly degraded mechanical properties of the silicone (p < 0.05).

Conclusions: Mechanical properties of maxillofacial elastomers are adversely affected by human and environmental factors. Mixed aging of storage in simulated sebum under accelerated daylight aging was the most degrading regime.

Clinical Significance: Accelerated aging of silicone specimens in simulated sebum under artificial daylight for 12 months of simulated clinical service greatly affected functional properties of silicone elastomer; however, in real practice, the effect is modest, since sebum concentration is lower, and daylight is less concentrated.
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http://dx.doi.org/10.1111/j.1532-849X.2011.00736.xDOI Listing
August 2011

3D-FE analysis of soft liner-acrylic interfaces under shear loading.

Dent Mater 2011 May 26;27(5):445-54. Epub 2011 Feb 26.

Biomaterials Research Group, School of Dentistry, University of Manchester, Higher Cambridge Street, Manchester M15 6FH, UK.

Aim: To analyze the distribution of stresses at the bond interface of Molloplast-B soft-liner attached to PMMA acrylic surface of different geometries (smooth and rough) and at different load-application distances by 3D-FEA modeling of typical shear-bond test. Methodology Three-dimensional finite element analysis (3D-FE) was performed utilizing Patran and Marc softwares (MSC.Software, USA). Models of Molloplast-B disk liner (diameter: 8mm, thickness: 3mm) bonded to smooth and rough acrylic geometries were designed. A total of 8 models (4 models for each surface geometry) were used to analyze Von Mises, maximum principal and shear stresses for the nodes corresponding to the vertical diameter of the acrylic-liner interface when applying a uniform shear-loading at different distances from the interface; 0.25, 0.5, 1, and 2mm. Materials properties were assumed to be isotropic, homogeneous, linear and elastic.

Results: Shear loadings, at various distances from the bond-interfaces, produced different magnitudes of shear and tensile stresses. They were more uniform for both smooth and rough geometries when loading was applied at smaller distances from the interface (0.25 and 0.50). The maximum shear stress did not surpass maximum tensile stress in the areas subjected to the highest stress. These values were higher for the models with increased distances and bending moment associated with rough surfaces.

Conclusions: It can be concluded that in conducting shear bond tests, shear and tensile stresses are present regardless of the distance from the bond interface at which the shearing stress is applied. However, at increased distances from the bond interface, tensile stresses are greater than shear stresses. When shear stress is applied at shorter distances from the bond interface (0.25 or 0.50mm), and regardless of bond-interface geometry; there is more uniform stress distribution and lower effect of bending moment. However, in vitro studies of bond strengths between soft liners and acrylic substrates obtained by shear test should be approached with caution, considering the distance of load application and the surface treatment of the substrate as the most important factors that could interfere with the shear test values.
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http://dx.doi.org/10.1016/j.dental.2011.01.003DOI Listing
May 2011

Effects of bond primers on bending strength and bonding of glass fibers in fiber-embedded maxillofacial silicone prostheses.

J Prosthodont 2011 Feb;20(2):113-9

Department of Allied Dental Science/Faculty of Applied Medical Sciences, Jordan University of Science and Technology, Irbid, Jordan.

Purpose: To evaluate the effect of three commonly used bond primers on the bending strength of glass fibers and their bond strength to maxillofacial silicone elastomer after 360 hours of accelerated daylight aging.

Materials And Methods: Eighty specimens were fabricated by embedding resin-impregnated fiber bundles (1.5-mm diameter, 20-mm long) into maxillofacial silicone elastomer M511 (Cosmesil). Twenty fiber bundles served as control and did not receive surface treatment with primers, whereas the remaining 60 fibers were treated with three primers (n = 20): G611 (Principality Medical), A-304 (Factor II), and A-330-Gold (Factor II). Forty specimens were dry stored at room temperature (23 ± 1°C) for 24 hours, and the remaining specimens were aged using an environmental chamber under accelerated exposure to artificial daylight for 360 hours. The aging cycle included continuous exposure to quartz-filtered visible daylight (irradiance 760 W/m(2) ) under an alternating weathering cycle (wet for 18 minutes, dry for 102 minutes). Pull-out tests were performed to evaluate bond strength between fiber bundles and silicone using a universal testing machine at 1 mm/min crosshead speed. A 3-point bending test was performed to evaluate the bending strength of the fiber bundles. One-way Analysis of Variance (ANOVA), Bonferroni post hoc test, and an independent t-test were carried out to detect statistical significances (p < 0.05).

Results: Mean (SD) values of maximum pull-out forces (N) before aging for groups: no primer, G611, A-304, A-330-G were: 13.63 (7.45), 20.44 (2.99), 22.06 (6.69), and 57.91 (10.15), respectively. All primers increased bond strength in comparison to control specimens (p < 0.05). Primer A-330-G showed the greatest increase among all primers (p < 0.05); however, bonding degraded after aging (p < 0.05), and pull-out forces were 13.58 (2.61), 6.17 (2.89), 6.95 (2.61), and 11.72 (3.03). Maximum bending strengths of fiber bundles at baseline increased after treatment with primers and light aging in comparison with control specimens (p < 0.05), and were in the range of 917.72 to 1095.25 and 1124.06 to 1596.68 MPa at both baseline and after 360 hours aging (p < 0.05).

Conclusions: The use of A-330-G primer in conjunction with silicone Cosmesil M511 produced the greatest bond strength for silicone-glass fiber surfaces at baseline; however, bond strength was significantly degraded after accelerated daylight aging. Treatment with primer and accelerated daylight aging increased bending strength of glass fibers.
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http://dx.doi.org/10.1111/j.1532-849X.2010.00653.xDOI Listing
February 2011

Porosity and color of maxillofacial silicone elastomer.

J Prosthodont 2011 Jan 5;20(1):60-6. Epub 2010 Nov 5.

Department of Allied Dental Science, Faculty of Applied Medical Sciences, Jordan University of Science and Technology, Irbid, Jordan.

Purpose: Prosthesis color production and stability as a result of pore entrapment during mixing has not been investigated for maxillofacial silicone prostheses. The purpose of this study was to investigate pore numbers and percentages of a maxillofacial silicone elastomer mixed by two different techniques, using X-ray microfocus computerized tomography (Micro-CT), and to investigate the effect of porosity on color reproducibility and stability after two different aging conditions.

Materials And Methods: Sixty-four disk-shaped specimens were prepared (8-mm diameter, 3-mm thick) by mixing TechSil S25 silicone elastomer (Technovent, Leeds, UK) following two techniques: manual mixing (n = 32) and mechanical mixing under vacuum (n = 32). Half the specimens in each group were intrinsically pigmented, and the other half remained unpigmented. Pore numbers, volumes, and percentages were calculated using the Micro-CT, and then specimens of each subgroup were stored in simulated sebum for 6 months (n = 8), and exposed to accelerated daylight aging for 360 hours (n = 8). Color change (ΔE) was measured at the start and end of conditioning. Pore numbers and percentages were analyzed using one-way Analysis of Variance (ANOVA) and Dunnett's-T3 post-hoc tests (p < 0.05). Independent t-test was used to detect differences (p < 0.05) in ΔE between manually and mechanically mixed specimens, in both unpigmented and pigmented states and to detect differences (p < 0.05) in ΔE before and after conditioning within each mixing method.

Results: Mechanical mixing under vacuum reduced the number and percentage of pores in comparison to manual mixing, within pigmented and unpigmented silicone specimens (p < 0.05). Perceptible ΔE between manual and mechanical mixing techniques were 5.93 and 5.18 for both unpigmented and pigmented specimens, respectively. Under sebum storage, manually mixed unpigmented specimens showed lower ΔE (p < 0.05) than those that were mechanically mixed; however, pigmented silicone specimens showed the same ΔE (p > 0.05). After light aging, mixing method had no effect on ΔE of unpigmented specimens (p > 0.05). Furthermore, mechanically mixed pigmented specimens showed lower ΔE (p < 0.05).

Conclusions: Within silicone elastomers (whether pigmented or unpigmented), mechanical mixing under vacuum reduced pore numbers and percentages in comparison to manual mixing. For selected skin shade, pores affected the resultant color of prosthesis (color reproducibility). Additionally, silicone pores affected silicone color stability upon service.

Clinical Significance: In fabricating maxillofacial prostheses, mechanically mixing silicone under vacuum produces pore-free prostheses, tending to enhance their color production and stability.
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http://dx.doi.org/10.1111/j.1532-849X.2010.00652.xDOI Listing
January 2011

Effect of extraoral aging conditions on color stability of maxillofacial silicone elastomer.

J Prosthodont 2010 Oct 16;19(7):536-43. Epub 2010 Aug 16.

School of Dentistry, The University of Manchester, Manchester, UK.

Purpose: Maxillofacial prostheses require enhancement or replacement due to deterioration in their color during service. The purpose of this study was to investigate color stability of pigmented and nonpigmented maxillofacial silicone elastomer exposed to different human and environmental aging conditions.

Material And Methods: One hundred and twelve disk-shaped silicone (TechSil S25, Technovent, Leeds, UK) specimens were prepared and equally divided into pigmented (using intrinsic rose-pink skin shade, P409, Principality Medical, Newport, UK) and nonpigmented categories of seven groups (n = 16; 8 pigmented and 8 nonpigmented): dark storage (control) (group 1), sebum solution storage (group 2), acidic perspiration storage (group 3), light aging (group 4), natural outdoor weathering (group 5), silicone-cleaning solution (group 6), and mixed conditioning of sebum storage and light aging (group 7). Conditioning periods (groups) were 6 months (groups 1, 2, 3, 5), 360 hours (groups 4, 7), and 30 hours (group 6). Color change (ΔE) was measured at the start and end of conditioning. In addition, for groups 1, 2, and 4, ΔE was measured at fixed intervals of 30 days, 15 days, and 30 hours, respectively. Data were analyzed with one-way analysis of variance (ANOVA), Dunnett's-T3 post hoc, and independent t-tests (p < 0.05). Linear regression was implemented to investigate ΔE with time for groups 1, 2, and 4.

Results: Six of the seven treatment conditions induced perceivable color change (ΔE > 3). Within the nonpigmented category, specimens stored in the dark for 6 months (group 1) exhibited high ΔE (6.17), which was greater (p < 0.05) than that produced by silicone-cleaning solution for 30 hours (group 6) (ΔE = 2.08). Within the pigmented category, light aging (group 4), outdoor (group 5), and mixed (group 7) conditionings induced greatest color changes (ΔE = 8.26, 8.30, 9.89, respectively) (p < 0.05); however, there was a strong positive linear function of log-time after dark storage (group 1) and light aging (group 4).

Conclusions: There is inherent color instability of nonpigmented silicone elastomer, which adds to the overall color change of silicone prostheses. Storing silicone elastomer in simulated sebum under light aging induced the greatest color changes. Overall, the color stability of TechSil S25 maxillofacial heat-temperature-vulcanizing (HTV) silicone elastomer was unacceptable (ΔE > 3.0, range from 3.48 to 9.89 for pigmented and 3.89 to 10.78 for nonpigmented) when subjected to six of the seven extraoral aging conditionings used in this study. Inherent color instability of nonpigmented facial silicone elastomers primarily contributes to the color degradation of extraoral facial prostheses. Sebaceous skin secretions along with daylight radiation cause the greatest perceivable color change to the silicone and pigment used in this study.
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http://dx.doi.org/10.1111/j.1532-849X.2010.00627.xDOI Listing
October 2010

Effects of accelerated artificial daylight aging on bending strength and bonding of glass fibers in fiber-embedded maxillofacial silicone prostheses.

J Prosthodont 2010 Jul 15;19(5):357-63. Epub 2010 Mar 15.

Biomaterials Research Group, School of Dentistry, The University of Manchester, Manchester, UK.

Purpose: The purpose of this study was to test the effect of different periods of accelerated artificial daylight aging on bond strength of glass fiber bundles embedded into maxillofacial silicone elastomer and on bending strength of the glass fiber bundles.

Methods And Materials: Forty specimens were fabricated by embedding resin-impregnated fiber bundles (1.5-mm diameter, 20-mm long) into maxillofacial silicone elastomer. Specimens were randomly allocated into four groups, and each group was subjected to different periods of accelerated daylight aging as follows (in hours); 0, 200, 400, and 600. The aging cycle included continuous exposure to quartz-filtered visible daylight (irradiance 760 W/m(2)) under an alternating weathering cycle (wet for 18 minutes, dry for 102 minutes). Pull-out tests were performed to evaluate bond strength between fiber bundles and silicone using a universal testing machine at 1 mm/min crosshead speed. Also a three-point bending test was performed to evaluate bending strength of the fiber bundles. One-way ANOVA and Bonferroni post hoc tests were carried out to detect statistical significance (p < 0.05).

Results: Mean (SD) values of maximum pull-out forces (in N) for groups 1 to 4 were: 13.63 (7.45), 19.67 (1.37), 13.58 (2.61), and 10.37 (2.52). Group 2 exhibited the highest pull-out force that was statistically significant when compared to the other groups. Maximum bending strengths of fiber bundles were in the range of 917.72 MPa to 1124.06 MPa. Bending strength significantly increased after 200 and 400 hours of aging only.

Conclusions: After 200 hours of exposure to artificial daylight and moisture conditions, bond strength between glass fibers and heat-cured silicones is optimal, and the bending strength of the glass fiber bundles is enhanced.
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http://dx.doi.org/10.1111/j.1532-849X.2010.00584.xDOI Listing
July 2010

Effect of net fiber reinforcement surface treatment on soft denture liner retention and longevity.

J Prosthodont 2010 Jun 19;19(4):258-62. Epub 2010 Feb 19.

School of Dentistry/Biomaterials Science Research Group, University of Manchester, Manchester, UK.

Purpose: To evaluate shear bond strength of Molloplast-B soft liner attached to different acrylic surfaces (smooth, rough, and Sticktech net fiber-reinforced interfaces) after 3000 thermal cycles.

Materials And Methods: Sixty-nine specimens were fabricated by attaching Molloplast-B soft liner to acrylic bases of three interfaces (n= 23); smooth (Group 1, control), rough (Group 2), and Sticktech net fiber-reinforced interface (Group 3). The specimens underwent 3000 thermocycles (5 and 55 degrees C) before being subject to a shear bond test at 2 mm/min crosshead speed. Debonding sites were investigated using an optical microscope at 40x magnification. Bond failures were categorized as adhesive, cohesive, or mixed.

Results: Mean (SD) bond strength values (MPa) were: 0.71 (0.15); 0.63 (0.07); and 0.83 (0.12) for smooth, rough, and fiber-reinforced acrylic interfaces, respectively. The mean values were analyzed using one-way ANOVA and Bonferroni post hoc test for pairwise comparisons (p< or = 0.05). The net fiber-reinforced acrylic interface exhibited a statistically significantly higher bond strength value when compared to smooth and rough acrylic interfaces (P= 0.003 and P= 0.000, respectively). Modes of failure were mainly cohesive (91%), followed by mixed failures (9%).

Conclusions: Molloplast-B exhibited a stronger bond to StickTech Net fiber-reinforced surfaces when compared to smooth and rough acrylic interfaces after thermocycling. This may enhance prosthesis serviceability during clinical use.
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http://dx.doi.org/10.1111/j.1532-849X.2009.00566.xDOI Listing
June 2010

Bonding of maxillofacial silicone elastomers to an acrylic substrate.

Dent Mater 2010 Apr 1;26(4):387-95. Epub 2010 Feb 1.

Biomaterials Research Group, School of Dentistry, University of Manchester, Higher Cambridge Street, Manchester, UK.

Objective: To investigate the effect of three different primers on shear and peel bond strengths between three maxillofacial silicone elastomers and an acrylic resin after 360 h of accelerated daylight-aging.

Materials And Methods: Peel and shear-bond strengths of three maxillofacial silicone elastomers (TechSil S25, Cosmesil M511, Cosmesil Z004) to acrylic denture resin bases using three adhesive primers (611, A304, A330-G) were assessed at baseline and after 360 h of accelerated artificial light-aging. Data were collected and statistically analyzed by two-way ANOVA, one-way ANOVA, and Bonferroni post hoc tests (alpha=0.05). Independent t-test was used to investigate the effect of light-aging on bond strengths (alpha=0.05). Modes of failure were visually analyzed and categorized as adhesive, cohesive, or mixed.

Results: In the peel bond test, at both baseline and after aging, there was a significant influence of primers and silicones on bond strength (p<0.001) and a strong interaction was also found between primers and silicones (p<0.05). Peel bond strengths ranged from 0.85 to 5.31 and 0.76 to 8.22 N/mm at baseline and after aging, respectively. The Z004 and 611 and Z004 and A330-G combinations showed the highest peel bond strength (5.31 and 8.22 N/mm, respectively) (p<0.05), as baseline and after aging. In the shear-bond test, there was only a significant influence of silicones on shear-bond strength (p<0.001), whereas primers did not affect it (p>0.05), and no interaction between primers and silicones was found (p>0.05). Shear-bond strengths ranged from 0.42 to 0.66 and 0.48 to 1.00 MPa at baseline and after aging, respectively. The combinations of Z004 and 611, Z004 and A304, Z004 and A330-G, M511 and A304, M511 and A330-G exhibited the highest bond strength (0.59-0.65 MPa) at baseline, and the Z004 with any of the primers (611, A304, and A330-G) showed greater bond strengths (0.89-1.00 MPa) (p<0.05) after aging. All the silicone elastomers at baseline, regardless of the adhesive primers, failed predominantly by cohesive debonding under peel and shear forces (68.9% and 100% respectively). However, after light-aging, peel and shear forces predominantly exhibited adhesive (79.5%) and cohesive (84.4%) failures, respectively.

Conclusions: Shear and peel test-regimes were both relevant and suitable for studying bonding and debonding characteristics of maxillofacial silicone elastomers bonded to an autopolymerising acrylic resin. The silicone/acrylic bond strengths were different for shear versus peel tests: 0.42-1.00 MPa for shear and 0.51-8.22 N/mm for peel. Cohesive failures were predominant with shear-tests, whereas peel-tests showed predominant cohesive failures at baseline but adhesive failures after light-aging. The optimum bonding achieved (best bonding at baseline that increased or was unaffected after light-aging) varied between shear and peel. For shear, it was achieved using Cosmesil Z004, with any primer, and M511 (but only with A304, and 330-G primers). For peel, it was achieved using both Cosmesil Z004 and TechSil S25 bonded using A330-G primer. Consequently, Cosmesil Z004 along with primer A330-G was the optimum silicone/primer combination to select on the basis of bond strengths.

Significance: A wide variety of new maxillofacial silicone elastomers and primers used in this study gave serviceable bond strengths. However, Cosmesil Z004 along with primer A330-G gave the optimum silicone/primer combination to select on the basis of bond strengths.
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http://dx.doi.org/10.1016/j.dental.2010.01.001DOI Listing
April 2010

Mechanical properties and bonding of maxillofacial silicone elastomers.

Dent Mater 2010 Feb 4;26(2):185-91. Epub 2009 Nov 4.

Biomaterials Research Group, School of Dentistry, University of Manchester, Higher Cambridge Street, Manchester M14 5FH, UK.

Objectives: Maxillofacial silicone elastomers are used to replace facial parts lost through disease or trauma. However, these materials do not possess ideal properties. The purpose of this study was to investigate the mechanical properties of recently and previously introduced maxillofacial silicone elastomers and their bond strength to acrylic resin substrate.

Materials And Methods: Specimens of three maxillofacial silicone elastomers (TechSil S25, Cosmesil M511, and Cosmesil Z004) were prepared according to manufacturers' instructions. Tear and tensile strengths, elongation percentage, modulus of elasticity and hardness were evaluated for each material. Shear bond strengths of these silicone elastomers to primed acrylic resin surfaces were evaluated. Data was analyzed with 1-way ANOVA, Bonferroni, and Dunnett's T3 post hoc tests (P < 0.05).

Results: The tensile strength of S25 was higher than M511 and Z004 (P < 0.05). Also S25 had higher elongation percentage in comparison to the other materials (P < 0.05). Z004 and S25 were harder (P < 0.05) than M511. All materials had the same tear strength and modulus of elasticity (P > 0.05). Z004 had higher shear bond strength than S25 (P < 0.05). There was a positive linear correlation between shear bond strength, and tear strength (r = 0.974) and shore A hardness (r = 0.717).

Conclusions: All silicone elastomers tested showed desirable properties. TechSil S25 had more favorable combination of high tensile strength and elongation at break, comparable tear strength, and hardness within the favorable range. However, Cosmesil Z004 was more resistant to shear debonding than other silicone elastomers.

Significance: TechSil S25 silicone elastomer has promising properties that favor its use in fabricating maxillofacial prostheses.
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http://dx.doi.org/10.1016/j.dental.2009.10.001DOI Listing
February 2010