CLINICAL REPORT
Closed-eye orbital prosthesis: A clinical report Muhanad M. Hatamleh, BSc, MPhil, MSc, Dip, PhD,a Jason Watson, BMedSci,b and Dilip Srinivasan, MDc The crucial role of facial ABSTRACT features in daily interpersonal One of the most challenging prostheses to fabricate is an acceptable orbital prosthesis. Successful relationships is readily apprereconstruction of the complex missing tissues, the globe, muscle, skin, and bony elements requires ciated. High value is placed time and high levels of practical skill. A good match to the contralateral nondefect side will help upon personal attractiveness mask the underlying defect and give the patient confidence to return to normal, routine life. The in most societies, and most 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. people are sensitive to the This clinical report presents a patient who had an extended orbital exenteration and right maxeffect they have on others. illectomy to remove a maxillary squamous cell carcinoma. An alternative approach to constructing Changes in facial features are an orbital prosthesis was undertaken with the eye closed. Compared to the normal method of likely to be accompanied by fabrication, this process was less complex and quicker, made the prosthesis less “staring,” 1-3 various types of difficulties. camouflaged the defect, and reduced the detection of the prosthesis because of movements in the A patient’s self-perception, remaining eye. The patient engaged in his routine daily life, which reinforced his self-esteem, emotional stability, personalconfidence, and reintegration into the community. (J Prosthet Dent 2015;113:246-249) ity characteristics, and social circumstances appear to be the salient factors in dealing the contralateral site.10-14 The patient will continuously with maxillofacial defects and the rehabilitation procompare the artificial prosthesis to the ocular component cess,3 and, when esthetic and functional demands (iris and sclera), skin shape, texture, color, and the lids of cannot be surgically fulfilled, a facial prosthesis is a the contralateral eye. The lids are highly complex and practicable alternative.4-6 Such a prosthesis can improve mobile and are important in adding not only anatomic the patient’s appearance, enable early rehabilitation, contour but also personality and character specific to the shorten surgery and hospitalization time, lower treatpatient. The shaping of the lids is fixed in the definitive ment cost, and allow early psychosocial reintegrastage of fabrication, so the definitive waxing has to caption.1,2,7,8 In 2007, of 1200 facial and body prostheses ture many different “faces” of the patient. This is fabricated in the UK, orbital prostheses ranked third extraordinarily difficult to get right the first time. The (155 orbital).8 following clinical report presents an unusual process for Exenteration, or removal of the entire orbital contents fabricating an orbital prosthesis while the subject keeps (globe, muscle, fat, lids), is performed primarily to eradihis or her eye closed. cate malignant orbital tumors.9 Prostheses designed to cover the remaining defect and replace the missing tissues CLINICAL REPORT are commonly described as orbital prostheses. They can be retained by various methods from the anatomic undercuts A 63-year-old man was referred to the reconstructive left after surgery to medical adhesives or implants. clinic at the Maxillofacial Unit of Queens Medical Center In the majority of patients, satisfaction depends on in Nottingham, UK, for the fabrication of an orbital how the prosthetic eye (and its components) resembles prosthesis. After being diagnosed with a right maxillary
a
Senior maxillofacial prosthetist, Maxillofacial Department, King’s College Hospital, London, UK. Consultant maxillofacial prosthetist, Maxillofacial Department, Queens Medical Centre, Nottingham University Hospital Trust, Nottingham, UK. c Consultant maxillofacial surgeon, Maxillofacial Department, Queens Medical Centre, Nottingham University Hospital Trust, Nottingham, UK. b
246
THE JOURNAL OF PROSTHETIC DENTISTRY
March 2015
247
Figure 1. A, Patient presented with orbital defect extending into his right cheek. B, Silicone prosthesis fabricated. C, D, Prosthesis in situ.
squamous cell carcinoma, he underwent an extended right orbit exenteration that included part of the right cheek and a partial maxillectomy (Fig. 1A). The patient had received no radiotherapy after his primary surgery, and the site had healed well with no complications. After his initial healing (3 months), he was referred to a local prosthetist with little experience at his district general hospital. After 8 months and multiple visits to the hospital, he was provided with a poor prosthesis that he
Hatamleh et al
described as being “staring” and “angry looking.” He was unhappy and had immediately discarded the prosthesis. At the initial consultation in our department, he was dismissive of the possibility that his staring orbital prosthesis could be improved. We discussed possible alternative options, such as extended medical patches and custom, vacuum-formed shields. He was not happy with these options and wanted a skinlike alternative.
THE JOURNAL OF PROSTHETIC DENTISTRY
248
The idea began to form of a nonstaring orbit or a closed eye. He liked the idea, and we outlined the fabrication process for an adhesive-retained prosthesis. The first parts of the process were carried out conventionally.15 His extensive nasal ethmoid sinus complex was packed to relieve the sensitive tissues present. An extended alginate impression (Hydrogum; Coltène/Whaledent) was made of his right and left sides by following a closed impression technique. The impression was poured in hard dental stone (Crystacal R; British Gypsum), and then a wax prototype was fabricated based on this impression. An advantage of this technique was that once a few specific landmarks such as facial planes, contralateral orbital closed fissure angles, and the canthus position had been identified, much of the sculptural carving could be carried out without the patient present. The cast of the contralateral side had a detailed image of the closed eye. The skin shade was recorded at the initial consultation with a digital color system (SpectroMatch Ltd) as reported previously.6,16 Three color points were chosen to represent the base color of the skin tone, the skin underneath the eye, and the eyelids. The color of the eyelashes and eyebrow were also recorded by using natural hair samples from the patient’s head. These were cut and retained. The color formula of his skin tones was prepared and mixed from platinum-polymerized medical silicone elastomer (M511 Cosmesil; Principality Medical). The first wax sculpture was evaluated with the patient at the next visit and required minimal adjustment, and the color match was checked for consistency. The wax was flasked conventionally in a 2-part flask. The silicone was packed and polymerized at 100 C for 1 hour. Once bench cooled, the flask was opened, and the prosthesis was finalized. The patient’s hair collected at the initial visit was used to form eyelashes and an upper eyebrow. At the third visit, the prosthesis was fitted on the patient and external characterization was added (Fig. 1B). The patient expressed satisfaction with the definitive result, as it was less staring (Fig. 1C, D). DISCUSSION Eyes are generally the first features of the face to be noticed. A person in need of an ocular prosthesis may have lost or damaged his or her natural eye as a result of trauma, malignancy, or congenital absence.15 Each of these etiologies leaves its own physical characteristics and psychological traits; they can all be seen as traumatic outcomes for the patient. For example, removal after a diagnosis of malignancy brings with it the constant fear of recurrence. Common to them all, however, is the social stigma associated with facial abnormality. Persons with a
THE JOURNAL OF PROSTHETIC DENTISTRY
Volume 113 Issue 3
facial abnormality may experience great psychological disturbance, such as low self-esteem, depression, dissatisfaction with appearance, or low quality of life.17 Traumatic alterations to the face usually involve some changes in the person’s sense of identity and attractiveness. There is also uncertainty about how prosthetic treatment might improve or even make the defect more obvious to others. Facial prostheses can nominally improve a patient’s appearance and also provide much earlier rehabilitation than more complex surgical options. The patient can get an early inspection of the affected area, manage body image change at an early stage, and look after the defect, an important part of early psychosocial reintegration. This treatment highlights the fragile nature of prosthetic reconstructions. Nonliving material cannot express the underlying changes that are occurring. Orbital prostheses differ from nasal or auricular prostheses in the sense that they must appear alive. The eye is expressive, is part of the character of the person, and transmits mood and feeling directly to others. How can this be accurately copied to reflect the ever-changing life of the patient? Trying to capture this mood at a sculpture sitting based on a single gaze of a patient, mostly in the forward direction, is impossible,15 as this position becomes immediately invalid when the patient looks in a different direction. When the eye is closed, the problems of expression are immediately eliminated. The patient still had function and movement of the left side. The lack of movement on the right side resembled the aftereffects of a severe facial palsy after a stroke. At subsequent follow-ups, the patient supported the view that a closed eye was far less noticeable and more publically acceptable than an eye that did not coincide with the movement of the contralateral eye. The patient expressed extreme satisfaction and was confident wearing it. Gaspare Tagliacozzi (1545-1599), an Italian surgeon who became famous for his skill in reconstructive surgery, once stated, “We restore parts of the face which nature has given but which fortune has taken away, not so much that they may delight the eyes, but that they may bring up the spirit and help the mind of the afflicted.” CONCLUSION Orbital prostheses are challenging for both the practitioner and patient. Reproducing the expression, character, and personality of the patient present in the contralateral eye is almost impossible. This clinical treatment used an original approach of making a closed eye prosthesis that restored esthetics, simplified manufacture, and provided a compromise that was acceptable to the patient.
Hatamleh et al
March 2015
249
REFERENCES 1. Atay A, Peker K, Gunay Y, Ebrinc S, Karayazgan B, Uysal O. Assessment of health-related quality of life in Turkish patients with facial prostheses. Health Qual Life Outcomes 2013;11:11. 2. Nemli SK, Aydin C, Yilmaz H, Bal BT, Arici YK. Quality of life of patients with implant-retained maxillofacial prostheses: a prospective and retrospective study. J Prosthet Dent 2013;109:44-52. 3. Bailey LW, Edwards D. Psychological considerations in maxillofacial prosthetics. J Prosthet Dent 1975;34:533-8. 4. Scolozzi P, Jaques B. Treatment of midfacial defects using prostheses supported by ITI dental implants. Plast Reconstr Surg 2004;114:1395-404. 5. Chalian VA, Phillips RW. Materials in maxillofacial prosthetics. J Biomed Mater Res 1974;8:349-63. 6. Watson J, Hatamleh MM. Complete integration of technology for improved reproduction of auricular prostheses. J Prosthet Dent 2014;111:430-6. 7. Goiato MC, Pesqueira AA, Ramos da Silva C, Gennari Filho H, Micheline Dos Santos D. Patient satisfaction with maxillofacial prosthesis. Literature review. J Plast Reconstr Aesthet Surg 2009;62:175-80. 8. Hatamleh MM, Haylock C, Watson J, Watts DC. Maxillofacial prosthetic rehabilitation in the UK: a survey of maxillofacial prosthetists’ and technologists’ attitudes and opinions. Int J Oral Maxillofac Surg 2010;39: 1186-92. 9. Perman K, Baylis H. Evisceration, enucleation, and exenteration. Otolaryngol Clin North Am 1988;21:171-82. 10. Bi Y, Wu S, Zhao Y, Bai S. A new method for fabricating orbital prosthesis with a CAD/CAM negative mold. J Prosthet Dent 2013;110:424-8.
11. Dugad JA, Dholam KP, Chougule AT. Vacuum form sheet as a guide for fabrication of orbital prosthesis. J Prosthet Dent 2014;112:390-2. 12. Long JA, Gutta R. Orbital, periorbital, and ocular reconstruction. Oral Maxillofac Surg Clin North Am 2013;25:151-66. 13. Pruthi G, Jain V. Light weight prosthesis for a patient with bilateral orbital exenteration-a clinical report. J Prosthodont Res 2013;57:135-9. 14. Worrell E. Ocular prosthetic obturator: an innovative medical device. Br J Ophthalmol 2014;98:862-4. 15. Hatamleh MM, Haylock C, Hollows P, Richmond A, Watson J. Prosthetic eye rehabilitation and management of completely blind patients. Int J Prosthodont 2012;25:631-5. 16. Hatamleh MM, Watson J. Construction of an implant-retained auricular prosthesis with the aid of contemporary digital technologies: a clinical report. J Prosthodont 2013;22:132-6. 17. Robinson E, Rumsey N, Partridge J. An evaluation of the impact of social interaction skills training for facially disfigured people. Br J Plast Surg 1996;49:281-9. Corresponding author: Mr Jason Watson Queens Medical Centre Campus Nottingham University Hospital Trust Nottingham, NG7 2UH UNITED KINGDOM Email: [email protected] Copyright © 2015 by the Editorial Council for The Journal of Prosthetic Dentistry.
Noteworthy Abstracts of the Current Literature Influence of sintering conditions on low-temperature degradation of dental zirconia Inokoshi M, Zhang F, De Munck J, Minakuchi S, Naert I, Vleugels J, Van Meerbeek B, Vanmeensel K Dent Mater 2014;30:669-78 The effect of sintering conditions and concomitant microstructure of dental zirconia (ZrO2) ceramics on their low-temperature degradation (LTD) behavior remains unclear. Objectives. Therefore, their effect on LTD of dental ZrO2 ceramics was investigated. Methods. Three commercial pre-sintered yttria-stabilized dental zirconia materials were sintered at three temperatures (1450 C, 1550 C and 1650 C) applying three dwell times (1, 2 and 4h). Grain size measurements and LTD tests were performed on polished sample surfaces. LTD tests were performed at 134 C in an autoclave. The amount of monoclinic ZrO2 on the exposed surface was measured by X-ray diffraction (XRD). Results. Higher sintering temperatures and elongated dwell times increased the ZrO2 grain size. Simultaneously, a larger fraction of zirconia grains adopted a cubic crystal structure, resulting in a decreased yttria content in the remaining tetragonal grains. Both the larger grain sizes and the lower average stabilizer content made the tetragonal grains more susceptible to LTD. Overall, independent on the commercial dental zirconia grade tested, the specimens sintered at 1450 C for 1h combined good mechanical properties with the best resistance to LTD. Significance. In general, increased sintering temperatures and times result in a higher sensitivity to low-temperature degradation of Y-TZP ceramics. Reprinted with permission of the Academy of Dental Materials.
Hatamleh et al
THE JOURNAL OF PROSTHETIC DENTISTRY
Closed-eye orbital prosthesis: A clinical report Muhanad M. Hatamleh, BSc, MPhil, MSc, Dip, PhD,a Jason Watson, BMedSci,b and Dilip Srinivasan, MDc The crucial role of facial ABSTRACT features in daily interpersonal One of the most challenging prostheses to fabricate is an acceptable orbital prosthesis. Successful relationships is readily apprereconstruction of the complex missing tissues, the globe, muscle, skin, and bony elements requires ciated. High value is placed time and high levels of practical skill. A good match to the contralateral nondefect side will help upon personal attractiveness mask the underlying defect and give the patient confidence to return to normal, routine life. The in most societies, and most 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. people are sensitive to the This clinical report presents a patient who had an extended orbital exenteration and right maxeffect they have on others. illectomy to remove a maxillary squamous cell carcinoma. An alternative approach to constructing Changes in facial features are an orbital prosthesis was undertaken with the eye closed. Compared to the normal method of likely to be accompanied by fabrication, this process was less complex and quicker, made the prosthesis less “staring,” 1-3 various types of difficulties. camouflaged the defect, and reduced the detection of the prosthesis because of movements in the A patient’s self-perception, remaining eye. The patient engaged in his routine daily life, which reinforced his self-esteem, emotional stability, personalconfidence, and reintegration into the community. (J Prosthet Dent 2015;113:246-249) ity characteristics, and social circumstances appear to be the salient factors in dealing the contralateral site.10-14 The patient will continuously with maxillofacial defects and the rehabilitation procompare the artificial prosthesis to the ocular component cess,3 and, when esthetic and functional demands (iris and sclera), skin shape, texture, color, and the lids of cannot be surgically fulfilled, a facial prosthesis is a the contralateral eye. The lids are highly complex and practicable alternative.4-6 Such a prosthesis can improve mobile and are important in adding not only anatomic the patient’s appearance, enable early rehabilitation, contour but also personality and character specific to the shorten surgery and hospitalization time, lower treatpatient. The shaping of the lids is fixed in the definitive ment cost, and allow early psychosocial reintegrastage of fabrication, so the definitive waxing has to caption.1,2,7,8 In 2007, of 1200 facial and body prostheses ture many different “faces” of the patient. This is fabricated in the UK, orbital prostheses ranked third extraordinarily difficult to get right the first time. The (155 orbital).8 following clinical report presents an unusual process for Exenteration, or removal of the entire orbital contents fabricating an orbital prosthesis while the subject keeps (globe, muscle, fat, lids), is performed primarily to eradihis or her eye closed. cate malignant orbital tumors.9 Prostheses designed to cover the remaining defect and replace the missing tissues CLINICAL REPORT are commonly described as orbital prostheses. They can be retained by various methods from the anatomic undercuts A 63-year-old man was referred to the reconstructive left after surgery to medical adhesives or implants. clinic at the Maxillofacial Unit of Queens Medical Center In the majority of patients, satisfaction depends on in Nottingham, UK, for the fabrication of an orbital how the prosthetic eye (and its components) resembles prosthesis. After being diagnosed with a right maxillary
a
Senior maxillofacial prosthetist, Maxillofacial Department, King’s College Hospital, London, UK. Consultant maxillofacial prosthetist, Maxillofacial Department, Queens Medical Centre, Nottingham University Hospital Trust, Nottingham, UK. c Consultant maxillofacial surgeon, Maxillofacial Department, Queens Medical Centre, Nottingham University Hospital Trust, Nottingham, UK. b
246
THE JOURNAL OF PROSTHETIC DENTISTRY
March 2015
247
Figure 1. A, Patient presented with orbital defect extending into his right cheek. B, Silicone prosthesis fabricated. C, D, Prosthesis in situ.
squamous cell carcinoma, he underwent an extended right orbit exenteration that included part of the right cheek and a partial maxillectomy (Fig. 1A). The patient had received no radiotherapy after his primary surgery, and the site had healed well with no complications. After his initial healing (3 months), he was referred to a local prosthetist with little experience at his district general hospital. After 8 months and multiple visits to the hospital, he was provided with a poor prosthesis that he
Hatamleh et al
described as being “staring” and “angry looking.” He was unhappy and had immediately discarded the prosthesis. At the initial consultation in our department, he was dismissive of the possibility that his staring orbital prosthesis could be improved. We discussed possible alternative options, such as extended medical patches and custom, vacuum-formed shields. He was not happy with these options and wanted a skinlike alternative.
THE JOURNAL OF PROSTHETIC DENTISTRY
248
The idea began to form of a nonstaring orbit or a closed eye. He liked the idea, and we outlined the fabrication process for an adhesive-retained prosthesis. The first parts of the process were carried out conventionally.15 His extensive nasal ethmoid sinus complex was packed to relieve the sensitive tissues present. An extended alginate impression (Hydrogum; Coltène/Whaledent) was made of his right and left sides by following a closed impression technique. The impression was poured in hard dental stone (Crystacal R; British Gypsum), and then a wax prototype was fabricated based on this impression. An advantage of this technique was that once a few specific landmarks such as facial planes, contralateral orbital closed fissure angles, and the canthus position had been identified, much of the sculptural carving could be carried out without the patient present. The cast of the contralateral side had a detailed image of the closed eye. The skin shade was recorded at the initial consultation with a digital color system (SpectroMatch Ltd) as reported previously.6,16 Three color points were chosen to represent the base color of the skin tone, the skin underneath the eye, and the eyelids. The color of the eyelashes and eyebrow were also recorded by using natural hair samples from the patient’s head. These were cut and retained. The color formula of his skin tones was prepared and mixed from platinum-polymerized medical silicone elastomer (M511 Cosmesil; Principality Medical). The first wax sculpture was evaluated with the patient at the next visit and required minimal adjustment, and the color match was checked for consistency. The wax was flasked conventionally in a 2-part flask. The silicone was packed and polymerized at 100 C for 1 hour. Once bench cooled, the flask was opened, and the prosthesis was finalized. The patient’s hair collected at the initial visit was used to form eyelashes and an upper eyebrow. At the third visit, the prosthesis was fitted on the patient and external characterization was added (Fig. 1B). The patient expressed satisfaction with the definitive result, as it was less staring (Fig. 1C, D). DISCUSSION Eyes are generally the first features of the face to be noticed. A person in need of an ocular prosthesis may have lost or damaged his or her natural eye as a result of trauma, malignancy, or congenital absence.15 Each of these etiologies leaves its own physical characteristics and psychological traits; they can all be seen as traumatic outcomes for the patient. For example, removal after a diagnosis of malignancy brings with it the constant fear of recurrence. Common to them all, however, is the social stigma associated with facial abnormality. Persons with a
THE JOURNAL OF PROSTHETIC DENTISTRY
Volume 113 Issue 3
facial abnormality may experience great psychological disturbance, such as low self-esteem, depression, dissatisfaction with appearance, or low quality of life.17 Traumatic alterations to the face usually involve some changes in the person’s sense of identity and attractiveness. There is also uncertainty about how prosthetic treatment might improve or even make the defect more obvious to others. Facial prostheses can nominally improve a patient’s appearance and also provide much earlier rehabilitation than more complex surgical options. The patient can get an early inspection of the affected area, manage body image change at an early stage, and look after the defect, an important part of early psychosocial reintegration. This treatment highlights the fragile nature of prosthetic reconstructions. Nonliving material cannot express the underlying changes that are occurring. Orbital prostheses differ from nasal or auricular prostheses in the sense that they must appear alive. The eye is expressive, is part of the character of the person, and transmits mood and feeling directly to others. How can this be accurately copied to reflect the ever-changing life of the patient? Trying to capture this mood at a sculpture sitting based on a single gaze of a patient, mostly in the forward direction, is impossible,15 as this position becomes immediately invalid when the patient looks in a different direction. When the eye is closed, the problems of expression are immediately eliminated. The patient still had function and movement of the left side. The lack of movement on the right side resembled the aftereffects of a severe facial palsy after a stroke. At subsequent follow-ups, the patient supported the view that a closed eye was far less noticeable and more publically acceptable than an eye that did not coincide with the movement of the contralateral eye. The patient expressed extreme satisfaction and was confident wearing it. Gaspare Tagliacozzi (1545-1599), an Italian surgeon who became famous for his skill in reconstructive surgery, once stated, “We restore parts of the face which nature has given but which fortune has taken away, not so much that they may delight the eyes, but that they may bring up the spirit and help the mind of the afflicted.” CONCLUSION Orbital prostheses are challenging for both the practitioner and patient. Reproducing the expression, character, and personality of the patient present in the contralateral eye is almost impossible. This clinical treatment used an original approach of making a closed eye prosthesis that restored esthetics, simplified manufacture, and provided a compromise that was acceptable to the patient.
Hatamleh et al
March 2015
249
REFERENCES 1. Atay A, Peker K, Gunay Y, Ebrinc S, Karayazgan B, Uysal O. Assessment of health-related quality of life in Turkish patients with facial prostheses. Health Qual Life Outcomes 2013;11:11. 2. Nemli SK, Aydin C, Yilmaz H, Bal BT, Arici YK. Quality of life of patients with implant-retained maxillofacial prostheses: a prospective and retrospective study. J Prosthet Dent 2013;109:44-52. 3. Bailey LW, Edwards D. Psychological considerations in maxillofacial prosthetics. J Prosthet Dent 1975;34:533-8. 4. Scolozzi P, Jaques B. Treatment of midfacial defects using prostheses supported by ITI dental implants. Plast Reconstr Surg 2004;114:1395-404. 5. Chalian VA, Phillips RW. Materials in maxillofacial prosthetics. J Biomed Mater Res 1974;8:349-63. 6. Watson J, Hatamleh MM. Complete integration of technology for improved reproduction of auricular prostheses. J Prosthet Dent 2014;111:430-6. 7. Goiato MC, Pesqueira AA, Ramos da Silva C, Gennari Filho H, Micheline Dos Santos D. Patient satisfaction with maxillofacial prosthesis. Literature review. J Plast Reconstr Aesthet Surg 2009;62:175-80. 8. Hatamleh MM, Haylock C, Watson J, Watts DC. Maxillofacial prosthetic rehabilitation in the UK: a survey of maxillofacial prosthetists’ and technologists’ attitudes and opinions. Int J Oral Maxillofac Surg 2010;39: 1186-92. 9. Perman K, Baylis H. Evisceration, enucleation, and exenteration. Otolaryngol Clin North Am 1988;21:171-82. 10. Bi Y, Wu S, Zhao Y, Bai S. A new method for fabricating orbital prosthesis with a CAD/CAM negative mold. J Prosthet Dent 2013;110:424-8.
11. Dugad JA, Dholam KP, Chougule AT. Vacuum form sheet as a guide for fabrication of orbital prosthesis. J Prosthet Dent 2014;112:390-2. 12. Long JA, Gutta R. Orbital, periorbital, and ocular reconstruction. Oral Maxillofac Surg Clin North Am 2013;25:151-66. 13. Pruthi G, Jain V. Light weight prosthesis for a patient with bilateral orbital exenteration-a clinical report. J Prosthodont Res 2013;57:135-9. 14. Worrell E. Ocular prosthetic obturator: an innovative medical device. Br J Ophthalmol 2014;98:862-4. 15. Hatamleh MM, Haylock C, Hollows P, Richmond A, Watson J. Prosthetic eye rehabilitation and management of completely blind patients. Int J Prosthodont 2012;25:631-5. 16. Hatamleh MM, Watson J. Construction of an implant-retained auricular prosthesis with the aid of contemporary digital technologies: a clinical report. J Prosthodont 2013;22:132-6. 17. Robinson E, Rumsey N, Partridge J. An evaluation of the impact of social interaction skills training for facially disfigured people. Br J Plast Surg 1996;49:281-9. Corresponding author: Mr Jason Watson Queens Medical Centre Campus Nottingham University Hospital Trust Nottingham, NG7 2UH UNITED KINGDOM Email: [email protected] Copyright © 2015 by the Editorial Council for The Journal of Prosthetic Dentistry.
Noteworthy Abstracts of the Current Literature Influence of sintering conditions on low-temperature degradation of dental zirconia Inokoshi M, Zhang F, De Munck J, Minakuchi S, Naert I, Vleugels J, Van Meerbeek B, Vanmeensel K Dent Mater 2014;30:669-78 The effect of sintering conditions and concomitant microstructure of dental zirconia (ZrO2) ceramics on their low-temperature degradation (LTD) behavior remains unclear. Objectives. Therefore, their effect on LTD of dental ZrO2 ceramics was investigated. Methods. Three commercial pre-sintered yttria-stabilized dental zirconia materials were sintered at three temperatures (1450 C, 1550 C and 1650 C) applying three dwell times (1, 2 and 4h). Grain size measurements and LTD tests were performed on polished sample surfaces. LTD tests were performed at 134 C in an autoclave. The amount of monoclinic ZrO2 on the exposed surface was measured by X-ray diffraction (XRD). Results. Higher sintering temperatures and elongated dwell times increased the ZrO2 grain size. Simultaneously, a larger fraction of zirconia grains adopted a cubic crystal structure, resulting in a decreased yttria content in the remaining tetragonal grains. Both the larger grain sizes and the lower average stabilizer content made the tetragonal grains more susceptible to LTD. Overall, independent on the commercial dental zirconia grade tested, the specimens sintered at 1450 C for 1h combined good mechanical properties with the best resistance to LTD. Significance. In general, increased sintering temperatures and times result in a higher sensitivity to low-temperature degradation of Y-TZP ceramics. Reprinted with permission of the Academy of Dental Materials.
Hatamleh et al
THE JOURNAL OF PROSTHETIC DENTISTRY
