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Comparative Soft and Hard Tissue Responses to Titanium and Polymer Healing Abutments

Permanent Link: http://ufdc.ufl.edu/UFE0041745/00001

Material Information

Title: Comparative Soft and Hard Tissue Responses to Titanium and Polymer Healing Abutments
Physical Description: 1 online resource (46 p.)
Language: english
Creator: Richardson, Joseph
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: dental, implants, mucosa, peek, periimplant
Dentistry -- Dissertations, Academic -- UF
Genre: Dental Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Comparative Soft And Hard Tissue Responses To Titanium And Polymer Healing Abutments A dental implant at the time of placement is a direct communication from the oral cavity to the alveolar crest. Fortunately, soft tissue components exist that protect the implant structure within the bone. It is known that connective tissue fibers align parallel to the titanium surface circumferentially in order to ?seal? the communication of the junctional epithelium from the alveolar crest. To our knowledge there is limited information from human studies assessing the soft tissue interface for abutments with different material composition using clinical outcome measures. In order to test this hypothesis, sixteen patients were randomly assigned to either the experimental group (PEEK healing abutments) or the control group (Titanium healing abutments). Standard surgical protocols were applied to install Straumann Bone Level implants. Buccal and lingual cortical plate thickness (post-osteotomy) and alveolar ridge thickness (post-implant placement) were measured surgically during implant placement. Other clinical parameters used for comparative analysis were measured at 14 and 90 days postoperatively. They included plaque levels and bleeding on probing at four surfaces as well as probing depth and recession at six sites. In addition, width of keratinized mucosa around the healing abutment was measured from the three buccal surfaces. Lastly, radiographs were exposed at placement and 90 days postoperatively and subjected to comparative analysis to determine bone loss. The study was completed after 90 days and patients were referred for final abutment placement and restoration. Results demonstrate statistically significant differences regarding plaque accumulation between test and control groups (20.5% vs. 48.5%) at the two week examination. Secondly, implants of the test group had a significantly higher proportion of sites with probing depths < 3mm (87.9% vs. 47%) and lower proportion of sites with probing depths 4-5mm (12.1% vs. 48.5%) compared to the control group at fourteen days. No other notable clinical differences were observed between the test polymer abutments and the control titanium abutments. Findings of the current clinical study utilizing implants temporarily restored with PEEK or titanium healing abutments indicate that PEEK healing abutments do not render an increased risk for marginal bone loss and soft tissue recession during the initial healing period.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Joseph Richardson.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Wallet, Shannon.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0041745:00001

Permanent Link: http://ufdc.ufl.edu/UFE0041745/00001

Material Information

Title: Comparative Soft and Hard Tissue Responses to Titanium and Polymer Healing Abutments
Physical Description: 1 online resource (46 p.)
Language: english
Creator: Richardson, Joseph
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: dental, implants, mucosa, peek, periimplant
Dentistry -- Dissertations, Academic -- UF
Genre: Dental Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Comparative Soft And Hard Tissue Responses To Titanium And Polymer Healing Abutments A dental implant at the time of placement is a direct communication from the oral cavity to the alveolar crest. Fortunately, soft tissue components exist that protect the implant structure within the bone. It is known that connective tissue fibers align parallel to the titanium surface circumferentially in order to ?seal? the communication of the junctional epithelium from the alveolar crest. To our knowledge there is limited information from human studies assessing the soft tissue interface for abutments with different material composition using clinical outcome measures. In order to test this hypothesis, sixteen patients were randomly assigned to either the experimental group (PEEK healing abutments) or the control group (Titanium healing abutments). Standard surgical protocols were applied to install Straumann Bone Level implants. Buccal and lingual cortical plate thickness (post-osteotomy) and alveolar ridge thickness (post-implant placement) were measured surgically during implant placement. Other clinical parameters used for comparative analysis were measured at 14 and 90 days postoperatively. They included plaque levels and bleeding on probing at four surfaces as well as probing depth and recession at six sites. In addition, width of keratinized mucosa around the healing abutment was measured from the three buccal surfaces. Lastly, radiographs were exposed at placement and 90 days postoperatively and subjected to comparative analysis to determine bone loss. The study was completed after 90 days and patients were referred for final abutment placement and restoration. Results demonstrate statistically significant differences regarding plaque accumulation between test and control groups (20.5% vs. 48.5%) at the two week examination. Secondly, implants of the test group had a significantly higher proportion of sites with probing depths < 3mm (87.9% vs. 47%) and lower proportion of sites with probing depths 4-5mm (12.1% vs. 48.5%) compared to the control group at fourteen days. No other notable clinical differences were observed between the test polymer abutments and the control titanium abutments. Findings of the current clinical study utilizing implants temporarily restored with PEEK or titanium healing abutments indicate that PEEK healing abutments do not render an increased risk for marginal bone loss and soft tissue recession during the initial healing period.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Joseph Richardson.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Wallet, Shannon.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0041745:00001


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1 COMPARATIVE SOFT AND HARD TISSUE RESPONSES TO TITANIUM AND POLYMER HEALING ABUTMENTS By JOSEPH P HILIP RICHARDSON A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMEN TS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2010

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2 2010 Joseph Philip Richardson

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3 For my wife Cyndi

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4 ACKNOWLEDGMENTS I would like to thank Theo filo s Koutouzis and Tord Lundgren They are my mentors and friends. I am a be tter clinician and person because of their tireless commitment to my education.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 6 LIST OF FIGURES ................................ ................................ ................................ .......... 7 ABSTRACT ................................ ................................ ................................ ..................... 8 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 10 2 BACKGROUND ................................ ................................ ................................ ...... 12 Indication for Dental Implants in Modern Dentistry ................................ ................. 12 History of Root Form Endosseous Dental Implants ................................ ................ 13 Endosteal Implants ................................ ................................ ........................... 13 Osseointegration ................................ ................................ .............................. 14 Implant Design and Surfaces ................................ ................................ ........... 14 Implant material ................................ ................................ ......................... 15 Surface topography ................................ ................................ .................... 15 Peri Implant Mucosa ................................ ................................ ........................ 16 Characteristics of the peri implant mucosa ................................ ................ 16 Effect of materials on peri implant mucosa ................................ ................ 18 Biomedical Application of PEEK ................................ ................................ ............. 19 3 MATERIALS AND METHODS ................................ ................................ ................ 20 Implant Treatment ................................ ................................ ................................ ... 21 Clinical Examinations ................................ ................................ .............................. 22 Examiner Variability ................................ ................................ ................................ 22 Radiographic Examination ................................ ................................ ...................... 23 Data Analysis ................................ ................................ ................................ .......... 23 4 RESULTS ................................ ................................ ................................ ............... 34 5 DISCUSSION ................................ ................................ ................................ ......... 39 LIST OF REFER ENCES ................................ ................................ ............................... 43 BIOGRAPHICAL SKETCH ................................ ................................ ............................ 46

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6 LIST OF TABLES Table page 3 1 Demographics of patients i ncluded in the study.. ................................ .................. 25 4 1 Measurements recorded at 2 weeks and 3 months. ................................ ........... 36 4 2 Changes in peri implant mucosa height and k eratinized mucosa. ....................... 36

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7 LIST OF FIGURES Figure page 3 1 Two types of healing abutments ................................ ................................ ............ 26 3 2 Straumann Bone Level implant. ................................ ................................ ............. 27 3 3 Measurement of mucosal thickness ................................ ................................ ....... 28 3 4 Measurement of bone thickness ................................ ................................ ............ 29 3 5 Healing abutments at placement and 3 months ................................ ..................... 30 3 6 Measurement of p eri implant mucosa height ................................ ......................... 31 3 7 Measurement of keritinized tissue width ................................ ............................... 32 4 8 Radiographic Examinations ................................ ................................ ................... 33 4 1 Distribution of implant sizes an d locations ................................ ............................. 37 4 2 Cumulative distribiton of mesial and distal bone level changes ............................ 38

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8 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science COMPARATIVE SOFT AND HARD TISSUE RESPONSES TO TITANIUM AND POLYMER HEALING ABUTMENTS By Joseph Philip Richardson May 2010 Chair: Tord Lundgren Major: Dental Sciences A dental implant at the time of placement is a direct communication from the oral cavity to the alveolar crest. Fortunately, soft tissue components exist that protect the implant structure within the bone. It is known that connective tissue fibers align parallel junctional epithelium from the alveolar crest. To our knowledge there is limited information from human studies assessing the soft tissue interface for abutments with different material composition using clinical outcome measures. In order to test this hypothesis, sixteen patients were randomly assigned to either the experimental group (PEEK healing abutments) or the control group (Titanium healing abutments). Standard surgical protocols were applied to install Straumann Bone Level implants. Buccal and lingual cortical plate thickness (post-osteotomy) and alveolar ridge thickness (post-implant placement) were measured surgically during implant placement. Other clinical parameters used for comparative analysis were measured at 14 and 90 days postoperatively. They included plaque levels and bleeding on probing at four surfaces as well as probing depth and recession at six sites. In

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9 addition, width of keratinized mucosa around the healing abutment was measured from the thr ee buccal surfaces. Lastly radiographs were exposed at placement and 90 days postoperatively and subjected to comparative analysis to determine bone loss. The study was c ompleted after 90 days and patients were referred for final abutment placement and restoration. Results demonstrate statistica lly significant differences regarding plaque accumulation between test and control groups (20.5% vs. 48.5%) at the two week exami nation. Secondly, implants of the test group had a significantly higher proportion of sites with probing depths < 3mm (87.9% vs. 47%) and lower proportion of sites with probing depths 4 5mm (12.1% vs. 48.5%) compared to the control group at fourteen days. No other notable clinical differences were observed between the test polymer abutments and the control titanium abutments. Findings of the current clinical study utilizing implants temporarily restored with PEEK or titanium healing abutments indicate tha t PEEK healing abutments do not render an increased risk for marginal bone loss and soft tissue recession during the initial healing period.

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10 CHAPTER 1 INTRODUCTION Tissue integration to dental implants is a wound healing process that involves several st ages of t issue formation and degradation 1,2 The establishment of the mucosal barrier around the implant is characterized by the gradual shift from a coagulum to granulation tissue followed by the formation of a barrier epithelium and the matu ration of the connective tissue 3 The soft tissue around implants was described in a series of experimental studies 4,5,6, 7 Thus, the peri implant mucosa consisted of a 2mm long bar rier epithelium and a 1 connective tissue i 4 Collagen fibers occurre d in large proportions and were mainly aligned in a direction that was parallel to the implant surface. Furthermore, the connective tissue integration zone had a low density of blood vessels an d a large number of fibroblasts 8 Additional animal studies 9 d ocumented that the material used in the abutment portion of the implant was of decisive importance for the quality of the attachment that occurs between the mucosa and the implant. Hence, abutments made of titanium or highly sintered aluminum based ceramic established similar conditions for mucosal healing to the abutment surface and allowed the formation of an attachment that included one epithelial and one connective tissue portion that were about 2 mm and 1 1.5 mm high respectively. On the contrary, at s ites where the abutments made of gold alloy or dental porcelain were installed at second stage surgery, no proper attachment seemed to form at the abutment level, but the soft tissue margin receded and bone resorption occurred. The abutment fixture junctio n was hereby occasionally exposed

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11 There is limited information from human studies assessing the soft tissue interface for abutments with different material chemistry using clinic al outcome measures 10 To our knowledge there is limited data evaluating the effect of materials such as polymers that are commonly used for implant provisionalization on the peri implant soft tissue interface. The aim of the present study was to comparati vely evaluate soft and hard tissue responses to titanium and polymer provisional implant abutments over a three month period.

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12 CHAPTER 2 BACKGROUND Indication for Dental Implants in Modern Dentistry Records of ancient civilizations indicated that dental d iseases such as tooth decay and periodontal disease s have affected mankind for thousands of years. 11 As the initial stage in the gastrointestinal cascade of nutritional procurement, the action of teeth set the stage for subsequent enzymatic act ivity requi red for breakdown of a food bolus. This bolus travels through the body to be broken down for essential nutrients that all animals require to survive. Secondly, teeth play an important role in communication. Specifically in the English language, the appro ximation of the teeth, lips and tongue provide the appropriate phonetic sounds required to annunciate a vast majority of words. There is history long evidence of the importance of teeth from an esthetic and interpersonal perspective. In biblica l times, wri tten words have express ed the importance and acknowledge concepts of tooth color, evenness, alignment, bilateral symmetry, and completeness. It is with these concepts that the value and appreciation of these attributes are expressed. 12 These very same con cepts could not be more exaggerated today. Dental implants provide a means for the replacement of missing teeth that have surpassed the traditional concepts and drawbacks of removable and fixed partial dentures. Dental implants also allow the restoratio n and prevention of further breakdown in a severely deteriorated alveolar complex.

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13 History of Root Form Endosseous Dental Implants The Glossary of Prosthodontic Terms 13 defines and implant as a prosthetic device or alloplastic material implanted into the oral tissues beneath the mucosal and/or periosteal layer, and/or within the bone to provide retention and support for a fixed or removable prosthesis. There are several forms of implants that have been used throughout history including transosteal epo ste al and endosteal With the exception of the endosteal implant, all other types were short lived and are no t considered the standard of care For the purposes of this discussion, only the endosteal implant will be discussed further. Endosteal Implants En dosteal implants include those that approximate the size and form of a tooth intraos category of endosteal implants; however, as referred to previously, only the endosseous root form implant as we know it today will be discussed further. A variety of materi als hav e been described to fabricate early dental implants including gold by Maggiolo in 1809, porcelain with roughened lead lining by Harris in 1886, platinum foil covered with lead and soldered with silver by Edmunds in 1889, iridio platiunum soldered with gold by Greenfield in 1909 and rubber pins by Brill in 1936. 14 Per Invar Br nemark and his colleagues completed

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14 experiments with bone healing around titanium surfaces, that the most widely used implant in the world today was inve nted. 15 To date, there are over 1,300 varieties of endosseous root form implants to choo se from in the United States alone 16 All varieties are structurally and functionally similar to those invented by Br nemark almost 60 years ago. Osseointegration In order to provide long term structural support under the masticatory forces in the oral ca vity, a dental implant must be inserted carefully and undergo a process termed osseointegration. Osseointegration refers to the direct structural and functional connection between ordered, living bone and the surface of a load carrying implant. 17 This d efinition supports the idea that under proper conditions, there is an absence of connective tissue or any non bone tissue in the interface between the implant and the bone. However, it is important to note that bone to implant contact (BIC) is only expect ed under light microscopy. Schroeder reports an amorphous, cell free layer, ranging in width from 20 to 1000nm and composed of glycosaminoglycans and proteoglycans interposed between the bone and the titanium 18 Implant Design and Surfaces The surgical pr ocess of implant placement requires initial fixation and lack of macromovement during the initial phases of the development of the implant bone interface in order to achieve osseointegration. It is important to emphasize that multiple factors play a role in proper integration and long term success of dental implant therapy. These factors include surface topography, thread design, implant material, bone quality, surgical technique and implant loading conditions. 17 Implant material and surface topography will be discussed in more detail as they are more relevant to this project.

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15 Implant material Since its biocompatibility was noted by Br nemark in 1982, titanium is the most widely used material to fabricate dental implants in the world. Titanium is a meta l that presents low weight, high strength weight ratio, low modulus of elasticity, excellent corrosion resistance, excellent biocompatibility, and easy shaping and finishing. 19 Titanium is used as a commercially pure variant (cpTi) or as an alloy. The mos t common alloy used for dental implants is composed of 90% titanium, 6% aluminum and 4% vanadium. 20 Although there are many studies that compare the two materials, the alloy is most often used today due to its mechanical advan tages of cpTi. The tit anium alloy is estimated to be four times stronger than grade 1 cpTi and 2.4 times stronger than grade 3 cpTi. 21 Due to similar values in BIC and reverse torque, the alloy is often used to decrease complications such as implant fracture. Surface topography Tur ned surfaces. The turned or machined surfaces were the most commonly used surface s in the past. They were machined and only sterilized prior to placement. accurate bec ause the machining process left grooves in the titanium surface. The machined implant was used universally until it was proposed that a shift be made from turned implants to purposefully roughened implants. Roughened surfaces. It was observed that the im plant surface morphology plays a role in stabilization of the implant (due to friction) and provides m ore surface area. 22 This lead s to a increased interaction between the surface of the i mplant and the cellular behavior that initiates osseointegration. 23 With this in mind, a variety of surface roughening method s were and continue to be developed. The ideal roughness for

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16 optimal bone formation is debatable and in fact, other characteristics such as wettability and free energy have since been studied to u nderstand their role in osseointegration. 24 Peri Implant Mucosa Although dental implants characteristically differ from teeth in multiple perspectives both entities are secured within the alveolar bone and pass transgingivally (or in the case of implant s transmucosally) into the oral cavi ty. Natural teeth erupt from the alveolar bone through the mucosa and into the oral cavity with a physical barrier or attachment of the epithelium and connective tissue directly to the supracrestal root surface. In heal thy cases, this attachment prevents subgingival bacterial invasion beyond the epithelial sulcus Similar conditions must be replicated in transmucosal dental implant therapy so that a seal is formed between the oral cavity and the alveolar crest that is s ecuring the stability of the implant body. Presumably, a higher quality seal will result in greater longevity of the implant. Characteristics of the peri implant mucosa Anatomy of peri implant mucosa. The anatomy of the peri implant mucosa around a denta l implant is widely based on evidence originally obtaine d from histological experiments in dogs and monkeys 4,26 The peri implant mucosa is established during wound healing that occurs subsequent to surgical flap closure at implant placement (or implant u ncovery a nd abutment attachment). It is compositionally similar to the macroscopic gingival comp lex around teeth including an epithelium and cellular composition and orien tation are much different. Composition and c ollagen fiber orientation. Schroeder et al in 1981 analyzed the soft tissue around implants placed in monkeys and reported the presence of

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17 26 In agreeme nt with Schroeder, Berglundh et al also noted the orientation of the collagen fibers and that they aligned parallel t o the surface of the implant as opposed to bundles of fibers that project lateral, coronal, and apical directions from the tooth root. 4,26 Furthermore, it was also noted in the same article that there was a higher concentration of collagen fibers but fewer fibroblasts and vascular structures compared to the gingival apparatus around a to oth. This was further validated in a dog study by Moon et al in 1999 where two zones were m zone of connective tissue contained a higher density of fibroblasts and lower volum e of fibroblasts than the adjacent outer 160 m zone 8 They also suggested that the thi n fibroblast rich barrier next to the titanium surface plays a role in the maintenance of proper seal between the oral environment and the peri implant bone. It is concluded from the above mentioned studies that the transmucosal att achment that occurs at implants is composed from a 2mm barrier epithelium ( th at is functionally similar to a junctional epithelium ) and a 1 1.5mm connective tissue zone that adheres to and runs a course parallel to the surface of the implant. Biologic widt h. Traditionally, the term biologic width refers to the minimum soft tissue dimension around teeth required to maintain the current alveolar bone level and is comprised of approximately 1mm of connective tissue and 1mm of junctional epithelial attachment to the root surface. 28 First, Berglund and Lindhe tested the 27 The invaded what they believed to be the minimum distance between the peri implant mucosa margin and the alveolar crest in five dog s and observed bone loss in those respective sites compared to

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18 an unchanged control side in each dog. Since the bone loss observed in the test sites was approximately the distance invaded, it was confirmed that there was a minimum i mplants 2 7 These findings were further confirmed by Cochran et al in 1997, when a similar dimension as described by Berglundh and Lindhe was observed when non submerged placement of implants resulted in an implant soft tissue junction that had a physiolo gic dimension that persisted despite being loaded. 7 Effect of materials on peri implant mucosa Implant surface. In further attempt to understand the characteristics of the peri implant mucosa, Abrahamsson in 1996 and 2002 observed the previously describ ed mucosal attachment in multiple implant systems. 6,32 He concluded that the attachment was the same despite the implant system used (and th e th eir respective surface characteristics) as well as whether or not the implants were submerged. Abutment materi al. In a continuing effort to identify the factors that affect peri implant mucosa dimensions, Abrahamsson in 1998 performed a study where the material composition of the transmucosal abutment was tested. 9 Abutments made of aluminum based sintered cerami c (Al 2 O 3 ), gold and dental porcelain were inserted and tested against titanium abutments. It was observed that the Al 2 O 3 allowed for the establishment of a mucosal attachment similar to that which occurred at titanium abutments; however, the gold alloy an d dental porcelain provided inferior conditions for mucosal healing and apical repositioning of the bone and soft tissue apparatus occurred until the proper dimension could be re established on the titanium surface of the implant. This simply exemplifies the decisive importance of the material that is to be chosen for the transmucosal abutment.

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19 Biomedical Application of PEEK Following confirmation of its biocompatibility two decades ago 31 polyaryletherketones (PAEKs) have been increasingly employed as b iomaterials for orthopedic, trauma, and spinal implants. Two PAEK polymers, used previously for orthopedic and spinal implants, include poly(aryl ether ether ketone) (PEEK) and poly(aryl ether ketone ether ketoneketone (PEKEKK).Numerous studies documenting the successful clinical performance of polyaryletherketone polymers in orthopedic and spinal patients continue to emerge in the literature 32,33 but very few reports exist about application of PEEK in dental implant therapy. Evaluation of oral mucosal inte gration at implant abutments made from PEEK material has not been performed in an animal model. However, several in vitro and animal studies have been performed confirming the biocompatibility of PEEK materials. Williams et al 31 reported the first animal studies of PEEK in the literature. Neat PEEK and carbon fiber reinforced samples were subcutaneously implanted in rabbits for 6 months and submuscularly implanted in rats for 30 weeks. Williams stated that PEEK models The growth and attachment of osteoblasts and fibroblasts to PEEK was evaluated by Hunter et al 34 in a series of cell culture experiments. 450G PEEK resin was employed and Ti alloy, CoCr alloy were used as controls. No significant differences were observed for fibroblast and osteoblast attachment among the various materials evaluated. The results of this study suggested that PEEK did not appear to deleteriously affect osteoblasts and fibroblasts

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20 CHAPTER 3 MATERIALS AND METHODS This study was design ed as a prospective, randomized, controlled clinical trial. Sixteen patients who had at least one tooth missing posterior to the maxillary or mandibular canine were enrolled in the study. The following conditions were reasons for excluding a subject from participating in the study: insufficient bone volume at the recipient sites for placement of an implant with a diameter of at least 4.1mm and length of at least 8mm, active infection or severe inflammation in the areas intended for implant placement, uncon trolled diabetes mellitus, hemophilia, metabolic bone disorders, history of renal failure, current chemotherapy and pregnancy, treatment with therapeutic radiation to the head region within the past 12 months, alcohol or drug abuse and smoking of more than 10cig/day. The study protocol was reviewed and approved by the Institutional Review Board of University of Florida. All subjects received detailed information on the study and signed a written consent before the start of the treatment. Control of periodon tal infection, if applicable, was achieved by an initial treatment phase consisting of scaling and root planing, motivation and oral hygiene instructions. If indicated, supplement mechanical debridement with periodontal surgery was performed. The initial t herapy was completed 30 60 days before the time of patient entry into the study. Patients were randomly assigned to a test or control treatment groups by a computer generated list. In the test group, following standard placement of the dental implant, a po lymer healing abutment (PEEK) was connected to the implant (test n=8). In the control group, following a similar dental implant installation procedure, a titanium

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21 healing abutment was connected to the implant (control n=8). Figure 3 1 illustrates componen ts used for test and control groups. The characteristics of the patients of the test and control groups are given in Table 3 1. Implant T reatment The implants used in the current study were Straumann Bone Level Implants with a diameter of 4.1mm or 4.8mm an d with lengths varying from 8mm to 12mm. The selection of implant type was based on existing bone dimensions. Figure 3 2 illustrates the structural characteristics of Straumann Bone Level Implant system. The surgical treatment performed under local anesthe two periodontists (J.R. and T.K.). Im mediately following local anest hesia, an endodontic file with a rubber stop was inserted into the buccal mucosa perpendicularly at a point 5mm apical to the crest of the ede ntulous ridge until bone contact was perceived. The rubber stop was positioned at the mucosal surface and the distance from the rubber stop to the tip of the endodontic file was measured to the lowest half millimeter to determine mucosal thickness (Figure 3 3 ) Crestal incisions were used and full thickness flaps were elevated to expose the bone. The recipient sites were enlarged according to the protocol of the manufacturer. Subsequent to osteotomy preparation, the thickness of buccal and lingual bony p lates was measured at a point 2mm apical to the crest of the ridge with a caliper instrument at the lowest half millimeter (Figure 3 4 ) Dental implants were installed in the edentulous segments according to patient needs. Healing abutments, either titani um (Straumann RC Healing Abutment, conical shape D 4.5mm, H 6mm) or polymer (Straumann RC Healing Abutment, customizable, D 7mm,polymer) were placed according to the randomi zation protocol (Figures 3 5 ). All

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22 abutments extended transmucosally and remained c ompletely out of occlusion. After abutment installation, the flaps were closed with interrupted sutures. Each patient received 1 g amoxicillin twice daily from the day of the implant surgery for seven days and chlorhexidine 0.12% rinse twice daily for two weeks. Three months following implant installation the prosthetic treatment was performed Clinical E xaminations At the 2 week and at the 3 month re examinations, the following clinical parameters were recorded at the im plant sites: presence of visible plaque (mesial, distal, buccal and lingual surfaces), probing depth (PD), bleeding on probing (BoP), peri implant mucosa height (PMH) at six sites of each implant (mesiobuccal, buccal, distobuccal, distolingual, lingual and mesiolingual). Peri implant mucosa height was recorded as the distance between the peri implant mucosa margin and the most coronal part of the healing abutment (Figure 3 6 ) In addition, the width of buccal keratinized mucosa was recorded as the linear di stance from the mucosal margin to the mucogingival line (Figure 3 7 ) All measurements performed with a manual probe (Hu Friedy PCP 15) to the lowest half millimeter. Examiner Variability The two periodontists that performed the surgical procedures also p erformed all clinical examinations. Each subject was assigned to one examiner. Before the start of the study, the examiners were trained to adequate levels of accuracy and reproducibility for the various clinical parameters to be used. The mean inter exami ner difference between repeated measurements was 0.14 (95% CI 0.02 to 0.3) for PD and 0.08 (95% CI 0.09 to 0.24) for PMH.

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23 Radiographic E xamination Radiographic examinations were performed immediately after the surgical procedure and at the 3 month follo w up visit (Figure 3 8 ). The periapical radiographs were taken in a standardized manner using a paralleling device (Dentsply Rinn, York, PA, USA) and a digital imaging software system (MIPACS USA). One periodontist (T.L.) that was not involved in the implan t therapy interpreted the radiographs. Measurements of the marginal bone level (distance between the abutment/fixture junction and the marginal bone to implant contact level) were made at the mesial and distal aspects of the implants. All measurements were determined using a magnification (x7) of the images. The ra diographs were downloaded as 16 bit, JPEG files and analyzed with an image processing system 29 on a laptop computer. The known geometry of each implant was used to assess the distortion of the ima ges. The error of the method used for appraising the measurements on the radiographs was calculated by reassessing 10 randomly selected cases including 40 sites. The mean difference between repeated measurements of the 40 sites was found to be 0.04mm (SD 0 .33 mm). Data A nalysis For description of data, mean values, standard deviations and cumulative frequencies were calculated. The primary outcome variable was the marginal bone level changes from the time of implant installation to the three month follow u p examination. on probing and pocket depth categories between the treatment groups. Differences in changes of peri implant mucosa height, buccal width of keratinized mu cosa and marginal bone levels between the groups were analyzed test

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24 thickness of the bone wall following the osteotomy (buccal and lingual) and cha nges in peri implant mucosa height (buccal and lingual) and thickness of buccal mucosa before implant placement and changes of buccal peri implant mucosa height. In all analysis a p value of <0.05 was considered to represent a statistically significant dif ference.

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25 Test Control Number of patients 8 8 Gender (male/female) 6/2 4/4 Mean age (SD) 59.1 (12.6) 54.2 (13.6) Smokers 0 0 Number of implants 11 11 Table 3 1. Demographics of patients included in the study. Table indicates number of patients gender, mean age, number of smokers, and total number of implants placed for each treatment group. There were no statistical differences between group demographics.

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26 Figure 3 1. This figure illustrates to two types of healing abutments used in the st udy. The control group (A) is a standard titanium healing abutment. The experimental group (B) is a PEEK healing abutment. Both components are currently commercially available by the Straumann Company.

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27 Figure 3 2. Th e structural and thread design o f the Straumann Bone Level implant

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28 Figure 3 3 Measurement of mucosal thickness. Endodontic file with rubber stopper was inserted approximately 5 mm from the mucosal margin. A rubber s top per was placed to the tissue The f ile was removed and mucosal thickness was measured with a periodontal probe

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29 Figure 3 4. T he thickness of buccal and lingual bony plates was measured at a point 2mm apical to the crest of the ridge with a caliper instrument at the lowest half millimeter

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30 Figure 3 5. Heal ing abutments, either titanium (Straumann RC Healing Abutment, conical shape D 4.5mm, H 6mm) labeled (A & B) or polymer (Straumann RC Healing Abutment, customizable, D 7mm,polymer) labeled (B & C) were placed according to the randomi zation protocol.

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31 Fi gure 3 6. Peri implant mucosa height was recorded as the distance between the peri implant mucosa margin and the most coronal part of the healing abutment (denoted by blue bracket). This measurem ent was performed at 6 sites arou nd implant ( MB, B, DB, DL, L, ML ).

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32 Figure 3 7. The width of buccal keratinized mucosa was recorded as the linear distance from the mucosal margin to the mucogingival line (denoted by the blue bracket). This measurement was performed at DB, B, and MB surfaces.

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33 Figure 3 8. R adiographic examinations were performed immediately after the surgical procedure and at the 3 month follow up vis it. A and B represent PEEK healing abutments at placement and 3 months respectively. C and D represent titanium healing abutments at placemen t and 3 months respectively.

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34 CHAPTER 4 RESULTS The distribution of diameter, length and position in the jaw of implants placed in the two g roups is illustrated at Figure 4 1 For both test and control groups 5 patients received one implant and three pati ents received two implants. The results of the clinical measureme nts are illustrated in Table 4 1 and Table 4 2 There was a statistically significant difference regarding plaque accumulation between test and control groups (20.5 % vs 40.9%) at the 2 week examination. Secondly, the test group implants had a significantly high er proportion of sites with PD < 3mm (87.9% vs 47%) and a lower proportion of sites with PD 4 5mm (12.1% vs 48.5%) compared to control group at the 2 week examination. There were no sign ificant differences between the two groups regarding plaque, BoP and frequencies of sites with different PD categories at the 3 month examination. No differences were detected between the different groups in changes of peri implant mucosa height and width of keratinized mucosa from 2 weeks to 3 months. For the test implants, the mean marginal bone level change at the 3 month follow up examination was 0.09 (0.2)mm for the mesial site and 0.04 (0.2) mm for the distal site. The corresponding numbers for the control group were 0.21 (0.40) mm and 0.28 (0.75) mm respectively. The mean marginal bone level change calculated with an implant level analysis was 0.02 (0.2)mm for the test group and 0.25(0.4)mm for the control group. There were no statistical signif icant differences between the two groups. The cumulative distribution of mesial and distal implant surfaces according to marginal bone level changes at the 3 month follow up examination is illustrated in

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35 Figure 4 2 None of the implant surfaces in the tes t group and 10% of the implant surfaces in the control group have marginal bone level reduction > 1mm. There were no significant correlations between the thickness of the bone wall following osteotomy preparation (buccal and lingual) and changes in peri i mplant mucosa height (buccal and lingual) (r=0.14, p=0.37) nor between thickness of buccal mucosa before implant placement and changes of buccal peri implant mucosa height (r=0.24, p=0.27).

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36 Plaque(%) BoP(%) PD 3mm (%) PD4 5mm(%) PD 6mm (%) Test (2 wee ks) 20.5* 31.8 87.9* 12.1* 0 Control(2 weeks) 40.9* 36.3 47* 48.5* 4.5 Test(3 months) 18.2 4.5 93.9 6.1 0 Control(3months) 6.8 12.1 87.9 12.1 0 Table 4 1. Measurements recorded at 2 weeks and 3 months. Frequencies (%) of sites with plaque, BoP, PD < 3mm, 4 5mm and > 6mm. Mesial Distal Buccal Lingual Keratinized M ucosa Test 0.04(0.8) 0.13(0.8) 0.09(0.5) 0.27(0.6) 0.01(0.8) Control 0.13(1.2) 0.36(0.7) 0.27(1.0) 0.18(0.6) 0.24(1.0) Ind ependent sample T test, P value non significant Table 4 2. Changes in peri implant mucosa height (M, D, B, L) and width of keratinized mucosa between 2 weeks and 3 months. Mean values and standard deviations are provided.

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37 Figure 4 1. Distribution of implant sizes used for test and control patients is labeled with

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38 Figure 4 2. The cumulative distribution of mesial and distal implant surfaces acc ording to marginal bone level changes at the 3 month follow up examination changes.

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39 CHAPTER 5 DISCUSSION The results of the present study failed to demonstrate that the mate rial of the healing abutment (PEEK or titanium) significantly influences soft tissue and bone level changes for the period of 3 months following implant installation. The soft tissue barrier around dental implants serves as a protective seal between the or al environment and the underlying peri implant bone. The integration of oral mucosa to implant components of different materials was examined in few studies. Abrahamsson et al 9 in an experimental study in dogs, reported that the abutment material was of decisive importance for the quality of the attachment that formed between the mucosa and the implant abutment. While abutments made of aluminum based ceramic provided conditions for a mucosal attachment that was similar to that of titanium, no proper muco sal attachment was formed to abutments made of gold alloy and dental porcelain. At such sites, recession of the mucosal margin and bone resorption occurred. Similar findings reported from Welander et al 30 that healing to abutments made of gold alloy was d ifferent than that at ceramic and titanium abutments. Although these studies demonstrate optimal soft tissue healing and dimensions for abutments made from titanium, aluminum based ceramic and zirconium, they do not provide information regarding abutments made from polymer materials that are very frequently used as healing abutments. Following confirmation of its biocompatibility two decades ago 31 polyaryletherketones (PAEKs) have been increasingly employed as biomaterials for orthopedic, trauma, and spina l implants. Two PAEK polymers, used previously for

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40 orthopedic and spinal implants, include poly(aryl ether ether ketone) (PEEK) and poly(aryl ether ketone ether ketoneketone (PEKEKK).Numerous studies documenting the successful clinical performance of polya ryletherketone polymers in orthopedic and spinal patients continue to emerge in the literature 32 33 but very few reports exist about application of PEEK in dental implant therapy. Evaluation of oral mucosal integration at implant abutments made from PEEK m aterial has not been performed in an animal model. However, several in vitro and animal studies have been performed confirming the biocompatibility of PEEK materials. Williams et al 31 reported the first animal studies of PEEK in the literature. Neat PEEK and carbon fiber reinforced samples were subcutaneously implanted in rabbits for 6 months and submuscularly implanted in rats for 30 weeks. Williams stated that PEEK The growth and attachment of osteobla sts and fibroblasts to PEEK was evaluated by Hunter et al 34 in a series of cell culture experiments. 450G PEEK resin was employed and Ti alloy, CoCr alloy were used as controls. No significant differences were observed for fibroblast and osteoblast attach ment among the various materials evaluated. The results of this study suggested that PEEK did not appear to deleteriously affect osteoblasts and fibroblasts. The results of our study are in agreement with in vitro and animal reports for PEEK material since no adverse events were experienced by the patients and similar soft tissue and bone responses were observed compared to the titanium healing abutments. In our study, we observed a statistically significant difference regarding plaque accumulation between PEEK and titanium abutments (20.5 % vs 40.9%) at the 2 week examination. During this period, the patients were instructed to use chlorhexidine 0.12%

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41 rinse twice daily without brushing the operated area. This difference was not expected due to the fact tha t the abutments made from PEEK material are slightly more rough compared to m for PEEK, data given from Straumann). These results are in contrast with the study by Wenneberg et al 35 They ev aluated in a clinical study the amount of plaque collected at titanium abutments with different degree of roughness for a period of four weeks and reported greater amounts of plaque for abutments with rougher surfaces. However, the abutments used in our st udy have a roughness similar to the ones that Wenneberg et al used as controls (0.259 0.430 m). The observed difference in plaque accumulation at the 2 week examination can be explained by the possible difference in compliance of the patients using the c hlorhexidine rinse and not by the minimal differences in roughness between the abutment materials. It should be noted that no significant differences were observed for plaque accumulation between the two groups at the 3 month examination. Implants for both groups showed minimal marginal bone loss during the 3 month healing period ( 0.02mm test group vs 0.25 mm control group). One limitation of the study is the short follow up period and one may assume that more bone loss might be expected for longer observ ational periods. However reports from both clinical 36,37 and animals studies 38 have shown that the largest amounts of marginal bone loss can take place following the first three months of implant installation with minor changes occurring subsequently. Dona ti et al 37 reported that the amount of bone loss using different installation protocols varied from 0.25mm to 0.38mm at one year with the major changes occurring at the first 3 months (0.2mm to 0.33mm). Cooper et al 36 in a study of

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42 early loading on impla nts placed with one stage procedure reported that about 0.4mm bone loss occurred during an initial 6 week period, with no further bone level changes at the subsequent 12 months follow up. Similarly Berglundh et al 38 in an animal study reported that the la rgest amount of bone loss occurred following implant installation and abutment connection with almost no bone level alterations during a 10 month period of functional load. In conclusion the findings of the current clinical study utilizing implants tempor ar ily restored with PEEK or titanium healing abutments indicate that PEEK healing abutments do not render an increased risk for marginal bone loss and soft tissue recession du ring the initial healing period.

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43 LIST OF REFERENCES 1. Berglundh T, Ab rahamsson I Lang NP, Lindhe J. De novo alveolar bone formation adjacent to endosseous implants. Clin Oral Implants Res 2003 ; 14(3):251 262. 2. Abrahamsson I, Berglundh T, Linder E, Lang NP, Lindhe J. Early bone formation adjacent to rough and turned endosseous impl ant surfaces. An experimental study in the dog. Clin Oral Implants Res 2004 ; 15(4):381 392 3. Berglundh T, Abrahamsson I, Welander M, Lang NP, Lindhe J. Morphogenesis of the peri implant mucosa: an experimental study in dogs. Clin Oral Implants Res 2007 ; 1 8(1):1 8. 4. Berglundh T, Lindhe J, Ericsson I, Marinello CP, Liljenberg B, Thomsen P. The soft tissue barrier at implants and teeth. Clin Oral Implants Res 1991 ; 2(2):81 90 5. Buser D, Weber HP, Donath K, Fiorellini JP, Paquette DW, Williams RC. Soft tissu e reactions to non submerged unloaded titanium implants in beagle dogs. J Periodontol 1992 ; 63(3):225 235. 6. Abrahamsson I, Berglundh T, Wennstrm J, Lindhe J. The peri implant hard and soft tissues at different implant systems. A comparative study in the dog. Clin Oral Implants Res 1996 ; 7(3):212 219 7. Cochran DL, Hermann JS, Schenk RK, Higginbottom FL, Buser D. Biologic width around titanium implants. A histometric analysis of the implanto gingival junction around unloaded and loaded non submerged implan ts in the canine mandible. J Periodontol 1997 ; 68(2):186 198 8. Moon IS, Berglundh T, Abrahamsson I, Linder E, Lindhe J. The barrier between the keratinized mucosa and the dental implant. An experimental study in the dog. J Clin Periodontol 1999 ; 26(10):65 8 663. 9. Abrahamsson I, Berglundh T, Glantz PO, Lindhe J. The mucosal attachment at different abutments. An experimental study in dogs. J Clin Periodontol 1998 ; 25(9):721 727. 10. Rompen E, Domken O, Degidi M, Pontes AE, Piattelli A. The effect of material c haracteristics, of surface topography and of implant components and connections on soft tissue integration: a literature review. Clin Oral Implants Res 2006 ;17 Suppl 2:55 67. 11. Taylor JA. History of Dentistry. Philadelphia, Lea and Febiger 1922 ; 19 21, 26 2 8, 148, 149. 12. Ring ME. Dentistry. An Illustrated History. New York, Abrams, 1985; 17, 28 45, 160.

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44 13. The Glossary of Prosthodontic Terms, Ed ition 7, St. Louis, Mosby, 1999; 65. 14. Ring ME. A thousand years of dental implants: A definitive therapy part 1. C ompendium 1995 ; 16:1060 1069. 15. Brnemark PI, Zarb GA, Albrektsson T. Tissue Integrated Prosthesis. Chicago, Q uintessence Publishing Co, Ind. 1985 ; 11 76. 16. Binon PP. Implants and components: entering the new millennium. Int J Oral Maxillofac Surg 2000; 15:76 94. 17. Albrektsson T, Brnemark PI, Hanson HA, Lindstrom J. Osseointegrated titanium implants. Acta Orthrop Scand 1981; 52:155. 18. Schroeder A, Sutter F, Krekeler G. Orale implantologie, allegemeine grundlagen und ITI Hohlzylindersystem. G Thieme Stut tgart, 1988. 19. Lautenschlager EP, Monaghan P. Titanium and tita nium alloys as dental materials. Int Dent J 1993 ; 43:245 253. 20. Scarano A, Piattelli M. Superfici implantari. In Novello G. Implantolgia pratica Courdenons, Italy, 2005; New Service Internatio nal. 21. Carr AB, Larsen PE, Gerard DA. Histomorphometric comparison of implant anchorage for two types of dental implants after 3 and 6 months healing in baboon jaws. J Prosthet Dent 2001 ; 85:276 280. 22. Johansson CB, Han CH, Wennerberg A et al A quantitat ive comparison of machined commercially pure titanium and titanium aluminum vandium implants in rabbit bone. Int J Oral Maxillofac Implants 1998 ; 13:315 321. 23. Brunette DM. The effects of implant surface topography on the behavior of cells. Int J Oral Ma xillofac Implants 1988 ; 3:231 236. 24. Rupp F, Scheideler L, Olshanska N et al Enhancing surface free energy and hydrophilicity through chemical modification of microstructured titanium implant surfaces J Biomed Mater Res A 2006 ; 76:323 334. 25. Schroeder, A The reactions of bone, connective tissue, and epithelium to endosteal implants with titanium sprayed surfaces. J Maxillofac Surg 1981 ; 9:15 25. 26. Gargiulo AW, Wentz FM, Orban B. Dimensions and relations of the dentogingival junction in humans J of Perio dontol 1961; 32:261 267. 27. Berglundh T, Lindhe J. Dimensions of the peri implant mucosa. Biological width revisited J Clin Periodontol 1996 ; 23:971 973.

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45 28. Abrahamsson I. The mucosal attachment to titanium implants with different surface characteristics: an experimental study in dogs J Clin Periodontol 2002 29:448 55. 29. ImageJ, U. S. National Institutes of Health, Bethesda, Maryland. Available at http://rsb.info.nih.gov/ij/, 1997 2008. Accessed April 12, 2009. 30. Welander M, Abrahamsson I, Berglundh T. The mucosal barrier at implant abutments of different materials. Clin Oral Implants Res 2008 ; 19(7):635 6 41. 31. Williams DF, McNamara A, Turner RM. Potential of polyetheretherketone (PEEK) and carbon fibre reinforced PEEK in medical applications. J Mat Sci Letters 1987; 6: 190 199 32. Toth JM, Wang M, E stes BT, Scifert JL, Seim HB Turner AS. Polyetheretherketone as a biomaterial for spinal applications. Biomaterials 2006; 27(3):324 334. 33. Brantigan JW, Neidre A, Toohey JS. The Lumbar I/F Cage for posterior lumb ar interbody fusion with the variable screw placement system: 10 year results of a Food and Drug Administration clinical trial. Spine J 2004; 4(6):681 688. 34. Hunter A, Archer CW, Walker PS, Blunn GW. Attachment and proliferation of osteoblasts and fibroblas ts on biomaterials for orthopaedic use. Biomaterials 1995; 16(4):287 295. 35. Wennerberg A, Sennerby L, Kultje C, Lekholm U. Some soft tissue characteristics at implant abutments with different surface topography. A study in humans. J Clin Periodontol 2003 ; 30(1):88 94. 36. Cooper L, Felton DA, Kugelberg CF, Ellner S, Chaffee N, Molina AL, Moriarty JD, Paquette D, Palmqvist U. A multicenter 12 month evaluation of single tooth implants restored 3 weeks after 1 stage surgery. Int J Oral Maxillofac Implants 2001 ; 16(2):182 192. 37. Donati M, La Scala V, Billi M, Di Dino B, Torrisi P, Berglundh T. Immediate functional loading of implants in single tooth replacement: a prospective clinical multicenter study. Clin Oral Implants Res 2008 ; 19(8):740 8. 38. Berglundh T, Abrah amsson I, Lindhe J. Bone reactions to longstanding functional load at implants: an experimental study in dogs. J Clin Periodontol 2005 ; 32(9):925 932.

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46 BIOGRAPHICAL SKETCH Joseph Philip Richardson was born in Lewiston, Maine in 1979 He grew up in Tavares, Florida and attended Wichita State University where he studied Chemistry. He graduated from the University of Florida College of Dentistry with a Doctor of Dental Medicine degree and attended the same institution for his specialty training in Periodontology. Upon graduation in the spring of 2010, he plans to join a private practice in Maitland, Florida and aspires to provide quality health care to all those who are in need.