The Journal of Prosthetic Dentistry

159March 2012

Schneider et alSchneider et al

This report describes the surgical and prosthodontic rehabilitation of a patient traumatized by a self-inflicted gun-shot wound to the mandible which required rehabilitation with a free fibula microvascular graft, single stage dental implant placement, and rehabilitation with CAD/CAM and laser assembled prosthetic components. (J Prosthet Dent 2012;107:158-162)

Complex mandibular rehabilitation of a self-inflicted gunshot wound: A clinical report

Robert Schneider, DDS, MS,a Kirk Fridrich, DDS, MS,b and Kristi Chang, MDc

University of Iowa Hospitals and Clinics, Iowa City, Iowa

aProfessor and Division Director, Maxillofacial Prosthodontics, Hospital Dentistry Institute.bProfessor and Head, Hospital Dentistry Institute.cAssociate Professor, Otolaryngology, Head and Neck Surgery Institute.

Self-inflicted gunshot wounds are devastating. Frequently the larger the caliber of the bullet, the more damage can be expected to hard and soft tis-sues.1,2 Rehabilitation of the resultant facial wounds is a significant challenge for the prosthodontist and surgical team. Recently the use of advanced 3-D imaging, microvascular grafts, and significant advances in prosthodontic techniques such as computer-aided design/computer-aided manufactur-ing (CAD/CAM) and laser assembled prostheses have allowed these pa-tients to be rehabilitated to near nor-mal function and esthetics.3-5

Several authors have illustrated the successful use of osseointegrat-ed implants in the reconstruction of traumatic craniomaxillofacial inju-ries.1-3-,6-9 A multidisciplinary team of several experienced clinicians and dental laboratory technicians was re-quired to rehabilitate the patient.

This article describes commonly used surgical techniques, dental clini-cal techniques, and dental laboratory procedures to provide a state of the art reconstruction of a self-inflicted gunshot wound of the mandible, em-phasizing the role of a team approach to patient treatment. In difficult or complex restoration situations, modi-fication of traditional techniques is

required. Modification of standard components and techniques will be presented.

CLINICAL REPORT A 39-year-old man presented with

a self-inflicted gunshot wound from a .40 caliber handgun to his right pos-terior mandible. In a hospital near the incident, he underwent closure of the lip, tongue, and mouth lacera-tions along with debridement and a percutaneous tracheostomy. When stabilized, he was transferred to the University of Iowa Hospitals and Clin-ics near his hometown.

When the patient arrived at the

University of Iowa Hospitals and Clinics, a computerized tomography (CT) scan and 3-D stereolithic medi-cal model (Medical Modeling Inc, Golden, Colo) was fabricated to as-sist in contouring a plate for his os-seous reconstruction (Fig. 1). He was taken to the operating room for fur-ther wound debridement, a left fibula free flap procedure, and mandibular reconstruction by a head and neck surgeon from the Otolaryngology department.5,6 Initial healing was un-eventful (Fig. 2).

After adequate healing of the fibu-la flap, the patient was referred to the Division of Maxillofacial Prosthodon-tics. On examination, he exhibited 1)

1 Lateral view of medical model of mandibular trauma gener-ated from CT scan showing extensive dentoalveolar damage.

some extraoral scarring from the fibu-lar reconstruction in the right sub-mandibular area, 2) a neck tracheos-tomy scar, and 3) a neck scar from the bullet entrance/exit wound. Intraoral evaluation of his dentition exhibited minimal restorations, no significant periodontal disease, and absence of the teeth distal to his mandibular right lateral incisor caused by the injury and resultant reconstructive surgery (Fig. 3). The occlusion was stable but not in the original maximum intercus-pal position (MICP) as a result of the fibula flap. A prosthodontic concern with his rehabilitation was that the skin paddle from the flap was in oc-clusion with the opposing dentition in the MICP, leaving minimal space for a prosthesis. The thickness of the skin paddles with such flaps is problem-atic in that they frequently preclude the use of a removable prosthesis and often require debulking to provide a firmer base for the planned prosthe-sis, which in this patient was to be an implant-supported fixed dental prosthesis. An alternative treatment plan for fabricating a partial remov-able dental prosthesis was also dis-cussed; however, the patient declined this plan. It was anticipated that the use of a removable dental prosthesis could be significantly compromised by the mobile soft tissue bed of the graft site.

After a debulking procedure of the skin paddle by the otolaryngolo-

gist and an appropriate healing pe-riod, mounted diagnostic casts were evaluated. A diagnostic waxing was completed for trial insertion and for patient evaluation and approval (Fig. 4). After approval, the patient was scheduled for implant placement by an oral and maxillofacial surgeon. A minimally restrictive surgical guide was provided to the surgeon, indicat-ing implant type and position. The minimal restriction was important as the surgeon was managing numer-ous factors such as the reconstruc-tion plate and its retaining screws. Optimal implant placement locations were limited.

Although a debulking procedure had been completed earlier, the thick-ness of the soft tissue at the proposed implant site was approximately 15 mm. As a single stage implant was to be used and as the maximum height of the manufactured healing abut-ments was 4.5 mm, tissue thickness required careful consideration. The prosthodontist waxed healing abut-ments to the desired height/dimen-sion and used a CAD (computer aided design) scanner (Etkon ES1; Straumann AG, Basel, Switzerland) to design an appropriate length healing abutment and custom milled 10 mm high titanium screw-retained healing abutments This made a single stage surgery possible.

The plan specified regular width platforms for the 2 anterior implants

and a wide platform for the molar. This required 2 different diameter custom designs, one for the standard diameter (4.8 mm) and one for the wide diameter (6.5 mm). The digital designs were sent to the milling cen-ter, and the healing abutments were milled from type IV titanium (Strau-mann AG)

The implant placement was un-eventful and was completed in a sin-gle stage surgery by using the custom, extended length, healing abutments. Hyperplastic tissue overgrowth led to coverage of some dental implants with skin; this was addressed with gingi-vectomy and improved hygiene before the definitive impressions were made7 (Fig. 5). Because of the atypical tis-sue thickness, another challenge was the length of routine stock impression copings for an implant-level impres-sion. At the request of the prosth-odontist, custom impression copings – double the standard 10 mm height – were fabricated by a dental labora-tory technician. By using the custom impression copings, implant level im-pressions were made with a custom tray (SternTek; Sterngold Dental, At-teboro, Mass) and a heavy bodied vinyl polysiloxane (Extrude; Kerr Cor-poration, Romulus, Mich). A verifica-tion index is useful in restoring mul-tiple implants to ensure the definitive cast accurately matches the patient. One custom impression coping and two 15 mm prefabricated impression

2 Radiograph of healed fibula graft. Note thickness of skin paddle in contact with opposing occlusion.

The Journal of Prosthetic Dentistry

159March 2012

Schneider et alSchneider et al

This report describes the surgical and prosthodontic rehabilitation of a patient traumatized by a self-inflicted gun-shot wound to the mandible which required rehabilitation with a free fibula microvascular graft, single stage dental implant placement, and rehabilitation with CAD/CAM and laser assembled prosthetic components. (J Prosthet Dent 2012;107:158-162)

Complex mandibular rehabilitation of a self-inflicted gunshot wound: A clinical report

Robert Schneider, DDS, MS,a Kirk Fridrich, DDS, MS,b and Kristi Chang, MDc

University of Iowa Hospitals and Clinics, Iowa City, Iowa

aProfessor and Division Director, Maxillofacial Prosthodontics, Hospital Dentistry Institute.bProfessor and Head, Hospital Dentistry Institute.cAssociate Professor, Otolaryngology, Head and Neck Surgery Institute.

Self-inflicted gunshot wounds are devastating. Frequently the larger the caliber of the bullet, the more damage can be expected to hard and soft tis-sues.1,2 Rehabilitation of the resultant facial wounds is a significant challenge for the prosthodontist and surgical team. Recently the use of advanced 3-D imaging, microvascular grafts, and significant advances in prosthodontic techniques such as computer-aided design/computer-aided manufactur-ing (CAD/CAM) and laser assembled prostheses have allowed these pa-tients to be rehabilitated to near nor-mal function and esthetics.3-5

Several authors have illustrated the successful use of osseointegrat-ed implants in the reconstruction of traumatic craniomaxillofacial inju-ries.1-3-,6-9 A multidisciplinary team of several experienced clinicians and dental laboratory technicians was re-quired to rehabilitate the patient.

This article describes commonly used surgical techniques, dental clini-cal techniques, and dental laboratory procedures to provide a state of the art reconstruction of a self-inflicted gunshot wound of the mandible, em-phasizing the role of a team approach to patient treatment. In difficult or complex restoration situations, modi-fication of traditional techniques is

required. Modification of standard components and techniques will be presented.

CLINICAL REPORT A 39-year-old man presented with

a self-inflicted gunshot wound from a .40 caliber handgun to his right pos-terior mandible. In a hospital near the incident, he underwent closure of the lip, tongue, and mouth lacera-tions along with debridement and a percutaneous tracheostomy. When stabilized, he was transferred to the University of Iowa Hospitals and Clin-ics near his hometown.

When the patient arrived at the

University of Iowa Hospitals and Clinics, a computerized tomography (CT) scan and 3-D stereolithic medi-cal model (Medical Modeling Inc, Golden, Colo) was fabricated to as-sist in contouring a plate for his os-seous reconstruction (Fig. 1). He was taken to the operating room for fur-ther wound debridement, a left fibula free flap procedure, and mandibular reconstruction by a head and neck surgeon from the Otolaryngology department.5,6 Initial healing was un-eventful (Fig. 2).

After adequate healing of the fibu-la flap, the patient was referred to the Division of Maxillofacial Prosthodon-tics. On examination, he exhibited 1)

1 Lateral view of medical model of mandibular trauma gener-ated from CT scan showing extensive dentoalveolar damage.

some extraoral scarring from the fibu-lar reconstruction in the right sub-mandibular area, 2) a neck tracheos-tomy scar, and 3) a neck scar from the bullet entrance/exit wound. Intraoral evaluation of his dentition exhibited minimal restorations, no significant periodontal disease, and absence of the teeth distal to his mandibular right lateral incisor caused by the injury and resultant reconstructive surgery (Fig. 3). The occlusion was stable but not in the original maximum intercus-pal position (MICP) as a result of the fibula flap. A prosthodontic concern with his rehabilitation was that the skin paddle from the flap was in oc-clusion with the opposing dentition in the MICP, leaving minimal space for a prosthesis. The thickness of the skin paddles with such flaps is problem-atic in that they frequently preclude the use of a removable prosthesis and often require debulking to provide a firmer base for the planned prosthe-sis, which in this patient was to be an implant-supported fixed dental prosthesis. An alternative treatment plan for fabricating a partial remov-able dental prosthesis was also dis-cussed; however, the patient declined this plan. It was anticipated that the use of a removable dental prosthesis could be significantly compromised by the mobile soft tissue bed of the graft site.

After a debulking procedure of the skin paddle by the otolaryngolo-

gist and an appropriate healing pe-riod, mounted diagnostic casts were evaluated. A diagnostic waxing was completed for trial insertion and for patient evaluation and approval (Fig. 4). After approval, the patient was scheduled for implant placement by an oral and maxillofacial surgeon. A minimally restrictive surgical guide was provided to the surgeon, indicat-ing implant type and position. The minimal restriction was important as the surgeon was managing numer-ous factors such as the reconstruc-tion plate and its retaining screws. Optimal implant placement locations were limited.

Although a debulking procedure had been completed earlier, the thick-ness of the soft tissue at the proposed implant site was approximately 15 mm. As a single stage implant was to be used and as the maximum height of the manufactured healing abut-ments was 4.5 mm, tissue thickness required careful consideration. The prosthodontist waxed healing abut-ments to the desired height/dimen-sion and used a CAD (computer aided design) scanner (Etkon ES1; Straumann AG, Basel, Switzerland) to design an appropriate length healing abutment and custom milled 10 mm high titanium screw-retained healing abutments This made a single stage surgery possible.

The plan specified regular width platforms for the 2 anterior implants

and a wide platform for the molar. This required 2 different diameter custom designs, one for the standard diameter (4.8 mm) and one for the wide diameter (6.5 mm). The digital designs were sent to the milling cen-ter, and the healing abutments were milled from type IV titanium (Strau-mann AG)

The implant placement was un-eventful and was completed in a sin-gle stage surgery by using the custom, extended length, healing abutments. Hyperplastic tissue overgrowth led to coverage of some dental implants with skin; this was addressed with gingi-vectomy and improved hygiene before the definitive impressions were made7 (Fig. 5). Because of the atypical tis-sue thickness, another challenge was the length of routine stock impression copings for an implant-level impres-sion. At the request of the prosth-odontist, custom impression copings – double the standard 10 mm height – were fabricated by a dental labora-tory technician. By using the custom impression copings, implant level im-pressions were made with a custom tray (SternTek; Sterngold Dental, At-teboro, Mass) and a heavy bodied vinyl polysiloxane (Extrude; Kerr Cor-poration, Romulus, Mich). A verifica-tion index is useful in restoring mul-tiple implants to ensure the definitive cast accurately matches the patient. One custom impression coping and two 15 mm prefabricated impression

2 Radiograph of healed fibula graft. Note thickness of skin paddle in contact with opposing occlusion.

160 Volume 107 Issue 3

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Schneider et al Schneider et al

copings (Etkon ES1; Straumann AG)were joined on the definitive cast with an autopolymerizing acrylic resin (GC Resin; GC America, Chicago, Ill) and used intraorally to verify passive fit,

radiographically and with the 1-screw test, before fabricating the prosthesis substructure10 (Figs. 6 and 7).

The definitive framework could either be fabricated with CAD/CAM

or with a laser assembled framework. Both options were explored and a ti-tanium laser-assembled framework processed with acrylic resin pros-thetic teeth was selected. The litera-

6 Assembled verification index ready for oral trial insertion.

7 Intraoral trial insertion of verification index confirming accuracy of definitive cast.

3 Frontal view of maximum intercuspation after debulk-ing of skin paddle.

8 Laser-assembled titanium framework fabricated on definitive cast with 15 mm custom milled abutments and stock components.

4 Frontal view of intraoral diagnostic waxing.

5 Healing and hyperplastic tissue.

used a second set of custom heal-ing abutments milled to 15 mm and standard titanium components to assemble the framework on the de-finitive cast (Fig. 8). The framework was opaqued (Gradia; GC America, Chicago, Ill) to prevent graying of the processed acrylic resin. The prosthet-ic teeth (Vitapan; Vident, Brea, Calif ) were arranged on the framework ac-cording to the diagnostic arrange-ment, and the prosthesis was com-pleted with an injection molding/polymerizing process (Ivocap; Ivo-clar Vivadent Inc, Amherst, NY). This process may result in less distortion to the framework than conventional press-pack techniques.

The completed prosthesis was re-turned from the laboratory and in-spected for accuracy (Figs. 9 and 10). Polished titanium was used for the transmucosal portion, and the gingival component of the prosthesis was de-signed as a modified ridge-lap pontic for ease of oral hygiene. The healing abutments were removed uneventfully, and the prosthesis was placed with the retaining screws tightened to the man-ufacturer’s specifications (Fig. 11). Oral hygiene was demonstrated and reinforced. A radiograph was made to verify fit and to serve as a baseline for future follow-up (Fig. 12).

The patient has shown satisfac-tory oral hygiene for the last 2 years. A chlorhexidine rinse (GUM alcohol-free chlorhexidine; Sunstar Americas Inc, Chicago, Ill) was locally applied around the implants affected by hy-perplastic tissue. It has been the expe-rience of the authors that hyperplastic tissue is a relatively common occur-rence with dental implants which protrude through skin as opposed to oral mucosa or gingiva. However, no changes in the alveolar bone levels around the implants have been not-ed. The patient is pleased with the es-thetic and functional outcomes. The authors will continue to recall this pa-tient annually for radiographic evalu-ation and every 4 months for routine scaling and prophylaxis.

9 Completed fixed prosthesis showing soft tissue con-tours for optimal oral hygiene.

10 Completed prosthesis showing polished transmuco-sal titanium custom abutments.

11 Frontal view of the prosthesis at insertion.

ture reveals various techniques for the successful fabrication of this type of restoration.8,11,12 This framework provides a better retentive and mate-rial support design than the available

CAD/CAM designs, especially with the extraordinary length required be-cause of the implant level, not abut-ment level, prosthesis design.

The dental laboratory technician

160 Volume 107 Issue 3

The Journal of Prosthetic Dentistry

161March 2012

Schneider et al Schneider et al

copings (Etkon ES1; Straumann AG)were joined on the definitive cast with an autopolymerizing acrylic resin (GC Resin; GC America, Chicago, Ill) and used intraorally to verify passive fit,

radiographically and with the 1-screw test, before fabricating the prosthesis substructure10 (Figs. 6 and 7).

The definitive framework could either be fabricated with CAD/CAM

or with a laser assembled framework. Both options were explored and a ti-tanium laser-assembled framework processed with acrylic resin pros-thetic teeth was selected. The litera-

6 Assembled verification index ready for oral trial insertion.

7 Intraoral trial insertion of verification index confirming accuracy of definitive cast.

3 Frontal view of maximum intercuspation after debulk-ing of skin paddle.

8 Laser-assembled titanium framework fabricated on definitive cast with 15 mm custom milled abutments and stock components.

4 Frontal view of intraoral diagnostic waxing.

5 Healing and hyperplastic tissue.

used a second set of custom heal-ing abutments milled to 15 mm and standard titanium components to assemble the framework on the de-finitive cast (Fig. 8). The framework was opaqued (Gradia; GC America, Chicago, Ill) to prevent graying of the processed acrylic resin. The prosthet-ic teeth (Vitapan; Vident, Brea, Calif ) were arranged on the framework ac-cording to the diagnostic arrange-ment, and the prosthesis was com-pleted with an injection molding/polymerizing process (Ivocap; Ivo-clar Vivadent Inc, Amherst, NY). This process may result in less distortion to the framework than conventional press-pack techniques.

The completed prosthesis was re-turned from the laboratory and in-spected for accuracy (Figs. 9 and 10). Polished titanium was used for the transmucosal portion, and the gingival component of the prosthesis was de-signed as a modified ridge-lap pontic for ease of oral hygiene. The healing abutments were removed uneventfully, and the prosthesis was placed with the retaining screws tightened to the man-ufacturer’s specifications (Fig. 11). Oral hygiene was demonstrated and reinforced. A radiograph was made to verify fit and to serve as a baseline for future follow-up (Fig. 12).

The patient has shown satisfac-tory oral hygiene for the last 2 years. A chlorhexidine rinse (GUM alcohol-free chlorhexidine; Sunstar Americas Inc, Chicago, Ill) was locally applied around the implants affected by hy-perplastic tissue. It has been the expe-rience of the authors that hyperplastic tissue is a relatively common occur-rence with dental implants which protrude through skin as opposed to oral mucosa or gingiva. However, no changes in the alveolar bone levels around the implants have been not-ed. The patient is pleased with the es-thetic and functional outcomes. The authors will continue to recall this pa-tient annually for radiographic evalu-ation and every 4 months for routine scaling and prophylaxis.

9 Completed fixed prosthesis showing soft tissue con-tours for optimal oral hygiene.

10 Completed prosthesis showing polished transmuco-sal titanium custom abutments.

11 Frontal view of the prosthesis at insertion.

ture reveals various techniques for the successful fabrication of this type of restoration.8,11,12 This framework provides a better retentive and mate-rial support design than the available

CAD/CAM designs, especially with the extraordinary length required be-cause of the implant level, not abut-ment level, prosthesis design.

The dental laboratory technician

162 Volume 107 Issue 3

The Journal of Prosthetic Dentistry Tan et alSchneider et al

SUMMARY

This treatment illustrates the value of a surgical and prosthetic team ap-proach in restoring a patient to near normal function and esthetics by us-ing current technology.

REFERENCES

1. Torabi K, Ahangari AH, Vojdani M, Fattahi F. Prosthodontic rehabilitation of a shotgun injury: a patient report. J Prosthodont 2010;19:634-8.

2. Sipahi C, Ortakoglu K, Ozen J, Caglar A. The prosthodontic restoration of a self-inflicted gunshot maxillofacial defect: a short-term follow-up case report. Int J Prosthodont 2007;20:85-8.

3. Cheung LK, Leung AC. Dental implants in reconstructed jaws: implant longevity and peri-implant tissue outcomes. J Oral Maxil-lofac Surg 2003;61:1263-74.

4. Stevens MR, Heit JM, Kline SN, Marx RE, Garg AK. The use of osseointegrated implants in craniofacial trauma. J Cranio-maxillofac Trauma 1998;4:27-34.

5. Wells MD. Part I. Mandibular reconstruc-tion using vascularized bone grafts. J Oral Maxillofac Surg 1996;54:883-8.

6. Roumanas ED, Markowitz BL, Lorant JA, Calcaterra TC, Jones NF, Beumer J 3rd. Re-constructed mandibular defects: fibula free flaps and osseointegrated implants. Plas Reconstr Surg 1997;99:356-65.

7. Mitchell DL, Synnott SA, VanDercreek JA. Tissue reaction involving an intraoral skin graft and CP titanium abutments: a clini-cal report. Int J Oral Maxillofac Implants 1990;5:79-84.

8. Jemt T, Henry P, Lindén B, Naert I, Weber H, Bergström C. A comparison of laser-welded titanium and conventional cast frameworks supported by implants in the partially edentulous jaw: a 3-year prospec-tive multicenter study. Int J Prosthodont 2000;13:282-8.

9. Wong TL, Wat PYP, Pow EHN, McMillan AS. Rehabilitation of a mandibulotomy/onlay/graft-reconstructed mandible using a milled bar and a tooth- and implant-sup-ported removable dental prosthesis: A clini-cal report. J Prosthet Dent 2010;104:1-5.

10.Tan KB, Rubenstein JE, Nicholls JI, Yuodelis RA. Three-dimensional analysis of the cast-ing accuracy of one piece, osseointegrated implant retained prostheses. Int J Prostho-dont 1993;6:346-63.

11.Rubenstein JE. Stereo laser welded titanium implant frameworks: clinical and laboratory procedures with a summary of 1-year clinical trials. J Prosthet Dent 1995;74:284-93.

12.Schneider R. Full mouth restoration on dental implants utilizing titanium laser-welded frameworks. J Esth Restor Dent 2009;21:215-26.

Corresponding author:Dr Robert L. SchneiderDivision Director, Maxillofacial ProsthodonticsHospital Dentistry InstituteUniversity of Iowa Hospitals and Clinics200 Hawkins Dr.Iowa City, IA 52242-1049Fax: 319-353-6923E-mail: robert-schneider@uiowa.edu

AcknowledgmentsThe authors thank the Iowa City Dental Ce-ramics (Iowa City, IA) for their scanning and providing the CAD/CAM custom abutments, and also Danny Roberts, CDT (Hawkeye Den-tal Studio, Cedar Rapids, IA) for his expertise in laser assembly and processing the definitive prosthesis are greatly appreciated.

Copyright © 2012 by the Editorial Council for The Journal of Prosthetic Dentistry.

12 Radiograph of prosthesis at insertion showing good fit previously evaluated with verification index.

Clinical ImplicationsThe failure of porcelain and its bond to zirconia is known to be the dominant clinical failure mechanism of zirconia based restorations. Meaningful knowledge of the porcelain to zirconia bond can be used to optimize zirconia surface preparation, firing schedules, and framework design.

Statement of problem. Porcelain fused to zirconia prostheses are widely used. However, porcelain chipping, spalling, fracture, and delamination are common clinical problems. Residual stresses of thermal origin have received attention, but clear data and firing guidelines remain absent.

Purpose. The purpose of this study was to measure the influence of heating and cooling protocols on the strength of porcelain fused to zirconia.

Material and methods. A modified 4-point flexural testing technique was used to measure strength, and porcelain buttons were bonded to the beam between the 2 central loading points. Beams (n=54) were made of a tetragonal polycrystalline zirconium dioxide that was partially stabilized with an yttria core and a feldspathic dental porcelain. Three different heating rates and 3 different cooling regimens were used during firing. Two-way analysis of variance (ANOVA) was used to evaluate the 2 main effects of the heating and cooling regimens and their interaction with the delamination force (α=.05). The Tukey multiple comparisons test was used to identify differences among heating or cooling regimens.

Results. During loading, the porcelain buttons separated from the zirconia beams because of delamination within the porcelain, which was close to the porcelain to zirconia interface. ANOVA revealed that the effects of the cooling regi-men and heating rate had statistically significant effects on failure load (P<.05). The effect of the cooling regimen was greater than that of the heating regimen.

Conclusions. Slow cooling and slow heating regimens should be used when firing porcelain to zirconia. Cooling regimens were found to be more influential than heating rates. Failure was localized to the porcelain adjacent to the porcelain-zirconia interface, not to the interface itself, indicating that the residual stresses of thermal origin within the porcelain dominated. The preparation of zirconia with 50 µm aluminum oxide at a pressure of 0.34 MPa was suffi-cient to prevent interfacial failure. (J Prosthet Dent 2012;107:163-169)

The use of slow heating and slow cooling regimens to strengthen porcelain fused to zirconia

John P. Tan, DDS,a Dalene Sederstrom, CDT,b Joshua R. Polansky, BA,c Edward A. McLaren, DDS,d Shane N. White, BDentSc PhDe

UCLA School of Dentistry, Los Angeles, Calif

Presented at the 22nd International Symposium on Ceramics, Los Angeles, California, June 2008 and the 23rd International Symposium on Ceramics, San Diego, California, June 2011

aPrivate practice, McAllen, Texas.bDental Laboratory Technician.cDental Laboratory Technician.dAdjunct Associate Professor.eProfessor.

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