2006 Research Forum Oral Session Abstracts

The abstracts below were presented at the 2006 AAP Annual Meeting Research Forum Oral Sessions on new and significant concepts related to periodontics. In the list below, click the title to view an abstract of the presentation.

ORAL SESSION I—WOUND HEALING, REGENERATION AND IMPLANTS

• A Comparative Study Utilizing Enamel Matrix Derivatives as Minimal-Invasive Treatment of Periodontal Intrabony Defects with and without Root Conditioning: A 24 Month Clinical-Controlled Study
• Conventional versus Modified Technique for Root Coverage Using Acellular Dermal Matrix: 36-month Comparative Follow-up
• Induction of Human Embryonic Stem Cell Differentiation by Periodontal Ligament Fibroblasts In Vitro
• Effect of Enamel Matrix-Derived, Transforming Growth Factor-β1 and Both on Human Periodontal Ligament Fibroblasts
• Phenotype Characteristics of Mouse Dental Follicle Cells at Different Developmental Stages
• Evaluation of Synthetic Polymers-Gelatin Composite Scaffold As rhBMP-2 Delivery System in Bone Regeneration
• PLAP-1: A Novel Negative Regulator of Mineralization of Periodontal Ligament
• Efficacy and Safety of rhGDF-5 in Advanced Intrabony Periodontal Defects in Dogs
• Effect of Calcium Phosphate Cement on In Vivo Osseous Repair Using a Critical Size Defect in the Rattus Norvegicus Calvarium
• Applicability of Calcium Phosphate Bone Cement in One-Wall Infrabony Defects
• Radiographic Bone Levels on 6x5.7 mm Implants: A 5-Year Follow-up Study
• An integrated System for 3D Imaging, Implant Planning and Guided Implant Surgery

ORAL SESSION II—RISK ASSESSMENT, PREVENTION AND TREATMENT

• Bioinformatic Prediction of Leader Genes in Human Periodontitis
• Positive Association of IL-1R2 with Aggressive Periodontitis in Japanese Population
• Expression of Antimicrobial Peptides, IL-8, and Bone Morphogenetic Proteins by Gingival Epithelial Cells in Response to Various Oral Bacteria
• Periodontopathic Bacteria are Resistant to Antimicrobial Peptides and Phagocytosis by Neutrophils
• The Effect of Periodontal Diagnosis and Prognosis on the Survival of Prosthodontic Abutments: A Pilot Study
• The effect of In Vitro Fertilization (IVF) Therapy on Periodontal Tissues
  I. Clinical Findings
• The effect of In Vitro Fertilization (IVF) Therapy on Periodontal Tissues
  II. Microbiological Results
• Conebeam CT Precision in Alveolar Bone Density Measurement
• Periodontal Treatment Improve the Systemic CRP and Pro-inflammatory Cytokine Levels
• Quadrant Root Planing Versus Same-Day Full-Mouth Root Planing With and Without Chlorhexidine
• Comparing the Efficacy of Two Mouth Rinses in Reducing Bacterial Aerosol Contamination
• Gingival Recession Treatment with Connective Tissue Grafts in Smokers and Non-Smokers

RESEARCH FORUM ORAL SESSION I
WOUND HEALING, REGENERATION AND IMPLANTS

Research contributor names, credentials, training institutions abstract content and abstract titles are listed below as provided by submitting author. In the list of authors for each abstract, an asterisk (*) indicates the presenting author at the Annual Meeting session.

A Comparative Study Utilizing Enamel Matrix Derivatives as Minimal-Invasive Treatment of Periodontal Intrabony Defects with and without Root Conditioning: A 24 Month Clinical-Controlled Study

Wolf-D. Grimm * D.D.S., University of Witten/Herdecke; Christian Kaltschmidt, University of Witten/Herdecke; Sylvia Lovrov, University of Witten/Herdecke; Sylvia Lovrov ,University of Witten/Herdecke

• Background: Studies have demonstrated that enamel matrix derivative (EMD) has the ability to improve clinical parameters when used to treat intrabony defects. The aim of this 24 months comparative study was to evaluate the efficacy of utilizing Enamel Matrix Derivatives as minimal-invasive treatment with and without root conditioning using clinical parameters and standardized radiographs.
• Methods: 31 patients displaying at least one pair of intrabony defects were chosen. 143 defects (20 patients) received EMD without root conditioning (EMDw-out). Thirty-five defects (11 patients) received EMD with root conditioning (EMDwith). At baseline and at 6, 12 and 24 months after surgery, the following clinical parameters were assessed: bleeding on probing (BOP), probing pocket depth (PPD), clinical attachment level (cAL) and gingival recession (GR). All intrabony defects were assessed for radiographical attachment level (rAL) differentiating into defect width (rALW) and depth (rALD) by standardized intraoral radiographs using stents to serve as fixed reference points. The statistical significance was tested applying the Wilcoxon rank test.
• Results: All clinical parameters improved statistically significant in respect to both analyzed groups (p 0.02): reduction of PPDw-out of 1,9mm±1,55mm in comparison to PPDwith of 2,9±1,2mm, reduction of cALw-out of 3mm±2,4mm in comparison to cALwith of 3,1±1,2mm. The average percent of defect fill after adjusting for defect width (rALW) and depth (rALD) showed no statistically significant results between the groups (rALWw-out 0,6mm ±0,9mm, rALDw-out -0,2mm±0,7mm, rALWwith 0,5mm±0,9mm, rALDwith –0,1mm ±1,2mm) after 24 month (p<0,23).
• Conclusion: From our results we conclude good soft tissue healing after minimal-invasive periodontal surgery including the use of EMD with and without root conditioning. Except in single cases no positive effect on bone regeneration due to EMD application with and without root conditioning could be demonstrated.

Conventional versus Modified Technique for Root Coverage Using Acellular Dermal Matrix: 36-month Comparative Follow-up

Mario Taba, Jr.,* D.D.S. University of Sao Paulo; Raquel Barros, University of Sao Paulo; Sergio Luis Scombatti de Souza, University of Sao Paulo; Daniela Palioto, University of Sao Paulo; Marcio Grisi, University of Sao Paulo; Arthur Belem Novaes, Jr., University of Sao Paulo

• Background: Long-term evaluation of gingival recession treatment is important for clinical decision-making. The aim of this clinical trial was to evaluate the acellular dermal matrix graft (ADMG) in the treatment of gingival recessions over a 3-year follow-up period, comparing a extended flap approach (test group) to a conventional procedure (control group).
• Methods: A total of 28 bilateral Miller Class I or II gingival recessions were selected and randomly assigned to test and control groups. Gingival recession (GR), width of keratinized tissue (KT), probing depth (PD) and relative clinical attachment level (RCAL) were assessed at baseline, 12 months and 36 months post-surgery.
• Results: Although both procedures improved all the evaluated parameters for all periods, comparisons between groups revealed statistically significant greater recession reduction favoring the new technique from baseline to the 12-month evaluation and from baseline to the 36-month evaluation (p=0.000). GR was 3.3 mm at baseline, 1.3 mm at 1 year and 1.4 mm at three years in the control group and 3.9 mm, 0.7 mm and 0.7 mm at the same periods in the test group. Statistically significant differences were not found between the 12-month and the 36-month evaluations, however the root coverage obtained with the conventional technique decreased from 60% at 1 year to 58% at 3 years, while for the new technique it remained stable around 83% over 3 years.
• Conclusion: In conclusion, the new technique is more suitable for root coverage with ADMG when compared to the other technique, showing a statistically significant better clinical performance that was maintained over a 3-year evaluation period.

Induction of Human Embryonic Stem Cell Differentiation by Periodontal Ligament Fibroblasts In Vitro

Bulend Inanc,* Ankara University, Biotech Institute and Gazi University; A. Eser Elcin, Ankara University, Biotech Institute and Gazi University; Evrim Unsal, Ankara University and Biotech Institute; Koksal Balos, Gazi University; Ates Parlar, Gazi University; Murat Elcin, Ankara University and Biotech Institute. This study was supported by AU-BIBAP 97; GU-BAP 03/2003-36; TUBITAK-TBAG 2370

• Background: Human embryonic stem cells (hESC) are pluripotent cells with unlimited proliferation potential and differentiation capacity to all types of somatic cells. Periodontal tissue engineering based on in vitro expanded cells holds the promise to overcome the limitations associated with contemporary regenerative techniques. The aim of this study was to investigate whether hESCs could be directed to differentiate towards the periodontal ligament progenitor cell lineage upon induction in vitro.
• Methods: Human embryonic stem cells (HUES-1 cell line) were expanded and characterized for pluripotency morphologically and immmunohistochemically. The cells were co-cultured with human periodontal ligament fibroblastic cells for 21 days. Two experimental groups were established with different medium constituents, and expansion cultures were used as controls. Specimens were fixed in the 7th, 14th, and 21st days and analyzed morphologically under inverted light microscope and immunohistochemically using antibodies against collagen type I, fibronectin, osteonectin, osteopontin, bone sialoprotein and osteocalcin.
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• Results: Morphological and immunohistochemical findings indicate different patterns of cell differentiation between groups, with fraction of cells in some areas of colonies acquiring characteristics similar to periodontal ligament fibroblastic progenitors.
• Conclusion: Results indicate the feasibility to direct the differentiation of human embryonic stem cells towards the periodontal ligament fibroblastic progenitors to some extent. With further improvement of the techniques, hESCs may become a cell source with unlimited supply for periodontal tissue engineering applications.

Effect of Enamel Matrix-Derived, Transforming Growth Factor-β1 and Both on Human Periodontal Ligament Fibroblasts

Daniela B. Palioto,* D.D.S., University of São Paulo; Thaisangela Rodrigues Lopes-Silva, University of São Paulo ; Julie Marchesan, University of São Paulo; Mario Taba Jr., University of São Paulo; Sergio Luis Scombatti de Souza, University of São Paulo; Arthur Belém Novaes Jr., University of São Paulo. This study was supported by FAPESP 02/07316-9.

• Background: Tissue regeneration is a complex biological process in itself, requiring intricately regulated interactions between cells and biological factors. Enamel matrix proteins (EMD) were recently introduced as biologic mediators to encourage periodontal regeneration. TGF-beta1 is the prototype of the TGF-beta superfamily of multifunctional peptides that controls cell proliferation, differentiation, and other functions in many types of cells. The objective of this study was to evaluate the effect of EMD, TGF-beta1, and the combination of these two factors (EMD+TGF-beta1) in periodontal ligament (PDL).
• Methods: Human PDL fibroblasts were obtained from premolars or third molars extracted for orthodontic reasons from three adult patients with clinically healthy periodontium, using explant technique. Proliferation rate was measured by counting cells at 1, 4, 7, and 10 days, and by incorporation of BrdU at 24 h. Cell adhesion was also analyzed by counting cells at 2 h. Wound healing was analyzed qualitatively at 2 and 6 days. Type I collagen production was determined by enzyme-linked immunosorbent assay (ELISA) at 3 days. Total protein content was determined using a modification of the Lowry method, and alkaline phosphatase (ALP) activity was assayed in the same lysates used for determining total protein content at 14 days. Bone-like nodule formation was evaluated qualitatively at 21 days.
• Results: Treatment with EMD at 4, 7 and 10 days increased cell proliferation compared to the negative control (p<0.05). At 10 days, EMD and EMD+TGF-beta1 showed greater cell proliferation compared to TGF-beta1 (p<0.01). Cell adhesion was significantly greater when sensitized with TGF-beta1 compared to EMD and EMD+TGF-beta1 (p<0.01). EMD seemed to enhance wound fill compared to the other treatments at 2 and 6 days. Collagen production of the TGF-beta1 group was greater than the positive control, EMD and EMD+TGF-beta1 (p<0.01). Total protein content was greater at 14 days with EMD than the other treatments (p<0.05). The negative control showed a total protein content lower than TGF-beta1 and EMD+TGF. At 14 days, treatment with EMD had higher ALP activity compared to the negative control and EMD+TGF-beta1. A modest bone-like nodule formation was observed in the EMD group.
• Conclusion: These findings support the hypothesis that EMD and TGF-beta1 may play a role in periodontal regeneration. EMD increased PDL fibroblast proliferation, wound healing, total protein content, ALP activity and mineralization. TGF-beta1 increased production of collagen and cell adhesion. However, the combination of both factors did not positively influence PDL fibroblast behavior.

Phenotype Characteristics of Mouse Dental Follicle Cells at Different Developmental Stages

Shaohua Ge,* School of Stomatology, Shandong University; Pishan Yang, School of Stomatology, Shandong University; Ning Zhao, School of Stomatology, Shandong University; Shu Li, School of Stomatology, Shandong University. This study was supported by Supported by National Natural Scientific Foundation of China (No.30371537).

• Background: Dental follicle(DF) has the ability to differentiate into periodontal ligament fibroblasts, cementoblasts and osteoblasts. The development of DF to periodontium is a precisely timed and sequenced event. The characteristics of DF cells varies and the factors are expressed sequentially in time. However, the sequence of cells differentiation and factors expression has not been confirmed. The purpose of this study was to explore the phenotype characteristics of DF cells and the expression sequence of matrix molecules at different developmental stages.
• Methods: DF of mandibular first molars from 3,5,7,9-day-old Balb/c mice were isolated and cultured in Dulbecco’s modified Eagle’s medium(DMEM) containing 10% fetal bovine serum(FBS). The shape and ultrastructure of cells were observed under introverted microscope, scanning electron microscope(SEM) and transmission electron microscope(TEM). Immunocytochemistry was used to detect the expression of alkaline phosphatase(ALP), collagen typeⅠ,bone sialoprotein(BSP), osteopontin(OPN) and osteocalcin(OCN).
• Results: There were two major cell types: some were cuboidal; the others were spindle-shaped. The cells were pleomorphism under SEM and had many filipodia and microvilli. DF cells had the ultrastructure of fibroblast-like cells, osteoblast-like cells and cementoblast-like cells. Cell composition of DF changed at different developmental stages: the cells were homogeneous at day 3 while heterogeneous cell subpopulations appeared at day 5,7,9. According to the expression of matrix molecules, DF cells could be divided into two subtypes: positive and negative. However, the presence time and expression amount were different: with the development of periodontium, the expression of ALP, BSP and OCN increased while that of collagen typeⅠand OPN decreased.
• Conclusion: DF had the potential of differentiating from homogeneous cells to heterogeneous cells. Moreover, it could differentiate into various types of cells and molecules expression changed at different stages of periodontium development.

Evaluation of Synthetic Polymers-Gelatin Composite Scaffold As rhBMP-2 Delivery System in Bone Regeneration

Chin-Lung Liu,* D.D.S., Department of Periodontology, National Taiwan University Hospital and Graduate Institute of Clinical Dental Sciences; Lein-Tuan Hou, Department of Periodontology, National Taiwan University; Bu-Yuan Liu, Department of Periodontology, National Taiwan University; Tai-I Lee, Graduate Institute of Clinical Dental Sciences; Yuan-Hui Sun, Graduate Institute of Clinical Dental Sciences. This study was supported by NSC grant 93-2314-B002-187.

• Background: Tissue engineering for bone regeneration relies on the presence of proper growth factors inside a suitable delivery system. Bone morphogenetic proteins (BMPs) are well-known important growth factors capable of inducing ectopic bone formation. However, an effective carrier/delivery system is critical for BMPs to accomplish this result. The objective of this study was to test the in vitro and ex vivo potential of the novel composite scaffold (synthetic polymers/gelatin) as a delivery system for rhBMP-2.
• Methods: The synthetic polymers poly(DL-lactide) (PLA) was incorporated with gelatin (GA) to be a composite (PLA/GA0 scaffold for carrying rhBMP-2. The structure, pore sizes, and cell affinity of PLA/GA and PLA were studied by scanning electron micrograph (SEM). In ex vivo assessment, PLA/GA and GA loaded with 30μg rhBMP-2 (rhBMP-2-PLA/GA, rh-BMP-2-GA) and PLA/GA control scaffolds were implanted into calf muscle of 16 male Wistar rats (4-5 weeks-old) to assess the ectopic bone formation in 3, 7, 14, and 28 days. The tissue blocks were harvested and ectopic bone formation was examined by histology with Masson's trichrome staining and immunohistochemistry of bone matrix proteins. RT-PCR analysis was performed for expression of alkaline phosphatase (ALP) and osteopontin (OPN). The compression strength between GA and PLA/GA was also compared.
• Results: All implants showed good biocompatibility without severe inflammatory responses or foreign body reaction. Under SEM observation, PLA showed a dense non-porous outer surface and a mean 10μm pore size with a poor pores interconnection inside. PLA/GA exhibited minimal porous outer surface while a larger inside porosity (pores size 50-60μm) than PLA. Cell affinity of PLA/GA was better than that of PLA. In ex vivo study, control scaffolds failed to induce bone formation throughout study. Initial ectopic bone formation was found in rhBMP-2-GA and rhBMP-2-PLA/GA at 7 and 14 days, respectively. The results of RT-PCR analysis indicated that rhBMP-2-PLA/GA induced ALP and OPN expression while PLA/GA showed better compression strength than the GA did.
• Conclusion: The PLA/GA composite scaffolds showed proper pore structure, good biocompatibility and seemed to have good mechanical property for space-making purpose in the present study. The rhBMP-2-PLA/GA induces ectopic bone formation, as shown by histology and gene expression, within 2 weeks. The results suggest that the novel PLA/GA composite may be a promising delivery system for carrying rhBMP-2 in tissue engineering of bone in dental implantology.

PLAP-1: A Novel Negative Regulator of Mineralization of Periodontal Ligament

Satoru Yamada ,* D.D.S., Osaka University Graduate School of Dentistry; Miki Tomoeda, Osaka University Graduate School of Dentistry; Yasuhiro Ozawa, Osaka University Graduate School of Dentistry; Masahiro Saito, Kanagawa Dental College; Shinya Murakami, Osaka University Graduate School of Dentistry. This study was supported in part by a Grant-in-Aid from the Japan Society for the Promotion of Science (No. 17390560 and 17390561).

• Background: PLAP-1 (periodontal ligament associated protein-1) is a recently-identified novel member of small leucine-rich repeat proteoglycan family. Recently significance of PLAP-1 in chondrogenesis and implications in the pathogenesis of osteoarthritis were identified. Here we report that PLAP-1 was also expressed specifically and predominantly in periodontal ligament (PDL) and regulated the mineralization of PDL cells.
• Methods: We assessed PLAP-1 expression in various tissues of mouse by RT-PCR. In order to examine PLAP-1 expression in mouse maxilla and tooth germs at different stages of development, in situ hybridization analysis was performed. To explore the role of PLAP-1 in cytodifferentiation and mineralization of PDL cells, we stably transfected MPDL22 (mouse PDL cell clone) with a vector containing PLAP-1 gene. We cultured the transfected cells in alpha-MEM supplemented with 10%FCS, 10mM beta-glycerophosphate and 50 microgram/ml ascorbic acid. Alkaline phosphatase (ALPase) activities and calcified nodule formation were evaluated by Bessay’s method and Alizarin Red staining, respectively.
• Results: RT-PCR and in situ hybridization revealed the specific and dominant expression of PLAP-1 in PDL tissues. During the course of tooth development, PLAP-1 mRNA was specifically detected in dental follicle which is the progenitor tissue to form cementum, alveolar bone and PDL. The ALPase activities and calcified nodule formation were significantly down-regulated in PLAP-1-over-expressing MPDL22.
• Conclusion: Present results demonstrated that PLAP-1 was expressed specifically in PDL tissues and probably functioned as a negative regulator of cytodifferentiation and mineralization of PDL cells.

Efficacy and Safety of rhGDF-5 in Advanced Intrabony Periodontal Defects in Dogs

Ulf ME Wikesjö,* Departments of Periodontics, Oral Biology & Maxillofacial Pathology, Medical College of Georgia Augusta Susanne Pippig, Scil Technology GmbH; Chong-Kwan Kim, Department of Periodontology, College of Dentistry, Yonsei University; Tae-Gyun Kim, Department of Periodontology, College of Dentistry, Yonsei University; Jung-Seok Lee, Department of Periodontology, College of Dentistry, Yonsei University Seong-Ho Choi, Department of Periodontology, College of Dentistry, Yonsei University

• Background: Autogenous bone represents the gold standard for bone grafting. Disadvantages include a second surgical procedure and donor site morbidity. Commercially available bone biomaterials may not predictably support bone formation. Thus development of novel biomaterials is desirable combining scaffolding and bone growth-inducing properties. The objective of this study was to evaluate the influence of GDF-5, an important factor in skeletal patterning and bone formation, in a ß-TCP or an ACS carrier on bone and cementum formation using an established dog model.
• Methods: Twenty adult Beagle dogs were used. Bilateral, critical-size, mandibular, one-wall, intrabony periodontal defects were implanted with recombinant human growth/differentiation factor-5 (GDF-5) in ß-tricalcium phosphate (ß-TCP) (rhGDF-5 at 20 µg) or absorbable collagen sponge ACS (rhGDF-5 at 0, 1, 20, 100 µg). Controls included ß-TCP and sham-surgery. Experimental sites were allowed to heal for 8 weeks following wound closure for primary intention healing when the animals were euthanized and block sections processed for histologic analysis.
• Results: Clinical healing was generally uneventful. rhGDF-5 based technologies showed significantly enhanced bone and cementum formation over controls (p<0.05). rhGDF-5/ß-TCP supported enhanced bone regeneration over rhGDF-5/ACS (p<0.05). Healing, in part, included a functionally oriented periodontal ligament. Limited, if any, adverse reactions were observed.
• Conclusion: rhGDF-5 supports bone and cementum formation in advanced intrabony periodontal defects. Application of rhGDF-5 appears safe as it is associated with limited, if any, adverse effects.

Effect of Calcium Phosphate Cement on In Vivo Osseous Repair Using a Critical Size Defect in the Rattus Norvegicus Calvarium

Richard L. Williams,* D.M.D., U.S. Army Periodontic Residency Program, Fort Gordon; Royce R. Runner, Department of Clinical Investigations, Eisenhower Army Medical Center, Fort Gordon; Gary D. Swiec, Director, U.S. Army Periodontic Residency Program, Fort Gordon; James C. McPherson III, Department of Clinical Investigations, Eisenhower Army Medical Center, Fort Gordon; Mohamed Sharawy, Medical College of Georgia

• Background: The purpose of this experiment was to evaluate the effect of a calcium phosphate cement [Norian® CRS® Fast Set™ Putty (CRS® Putty)] in the rat calvarial critical size defect and determine if superior bone-healing properties were demonstrated when compared to demineralized freeze-dried bone allograft (DFDBA).
• Methods: Fifty-three eleven-week old male Norwegian rats were randomly placed into the following surgical groups: Group I: DFDBA - 20 rats; Group II: CRS® Putty – 20 rats; Group III: 10 rats unfilled defect. A circular craniotomy procedure was performed on each animal. Defects were filled to capacity with the appropriate material and isolated by two sterile precut, 9-mm MilliporeTM PTFE membranes. Animals were sacrificed after 20 weeks. Data collection consisted of histomorphometric, radiographic, and strength comparison analyses. Strength tests were conducted on 10 rats from each of the treatment groups receiving graft materials (the CRS® Putty and DFDBA groups) and compared to specimens from a group of animals with intact calvaria (8-month-old retired male breeders).
• Results: The rate of bone formation and the strength test demonstrated no significant differences (P>0.05) among the three groups. Histomorphometrically, the DFDBA group demonstrated higher percent bone fill (31.0%) than the CRS® Putty group (26.4%) and the negative control (16.2%). Both experimental group values were significantly (P<0.05) higher than negative control values. Densitometric analysis showed the CRS® Putty group to be superior in mean percent radiographic density when compared to the other surgical treatment groups. Although there were no significant differences between the CRS® Putty and DFDBA groups (P>0.05), significant differences between the negative control and both the CRS® Putty and DFDBA groups (P<0.05) were noted.
• Conclusion: This guided bone regeneration (GBR) study showed CRS® Putty and DFDBA to be comparable in strength, amount of bone fill, and radiographic density. The results support future consideration of the CaPO4 cement as a bone replacement graft in periodontal therapy. It could also possibly serve as an effective treatment modality, in GBR cases, to manage voids or dehiscences around endosseous implants.

Applicability of Calcium Phosphate Bone Cement in One-Wall Infrabony Defects

Yoshinori Shirakata,* D.D.S., Department of periodontology Kagoshima University Graduate School of Medicine and Dental Sciences; Takehiko Yoshimoto, Department of periodontology Kagoshima University Graduate School of Medicine and Dental Sciences; Kadomatsu Hideshi, Department of periodontology Kagoshima University Graduate School of Medicine and Dental Sciences; Motoharu Miyamoto, Department of periodontology Kagoshima University Graduate School of Medicine and Dental Sciences; Toshiaki Nakamura, Department of periodontology Kagoshima University Graduate School of Medicine and Dental Sciences; Yuichi Izumi, Department of periodontology Kagoshima University Graduate School of Medicine and Dental Sciences. This study was supported by the Grant-in-Aid for Encouragement of Young Scientists (16791317) from the Ministry of Education, Science, Sports and Culture of Japan. The grafting material was provided by Shoufu Inc., Kyoto, Japan.

• Background: Although various periodontal regenerative therapies are currently in practice, their effects on non-contained infrabony defects are unpredictable. An earlier study showed that an injectable moldable, fast-setting calcium phosphate cement (CPC) promoted histocompatible periodontal healing in three-wall intrabony defects. This study was designed to evaluate healing pattern after surgical application of a CPC wall with or without enamel matrix derivative (EMD) in one-wall infrabony defects in dogs.
• Methods: One-wall infrabony defects were surgically created on the mesial and distal sides of bilatelal mandibular fourth premolars in 4 beagle dogs. After a full thickness flap was elevated, the exposed root surfaces were thoroughly planed. The sixteen defects were randomly assigned to one of the following treatments; CPC, CPC+EMD, EMD, and open flap debridement (OFD). Ten weeks postsurgery, the animals were sacrificed and histological specimens were prepared for histomorphometric evaluation.
• Results: Defect sites treated with EMD only exhibited new cementum and new bone formation to a varying extent, while the OFD group presented only limited new cementum and bone formation. Defect sites where a CPC wall was implanted revealed significantly greater regeneration of new bone and new cementum-inserting collagen fibers than the EMD or the OFD groups. No significant differences were observed between CPC treated groups.
• Conclusion: CPC wall with or without EMD promoted the regerenation of alveolar bone and cementum in one-wall infrabony defects. Providing space and stable wound healing might be crucial for periodontal regeneration in non-contained infrabony defects.

Radiographic Bone Levels on 6x5.7 mm Implants: A 5-Year Follow-up Study

Caterina Venuleo,* D.D.S., Boston University, Goldman School of Dental Medicine, Department of Periodontology; Sung-Kiang Chuang, Harvard University, School of Dental Medicine; Meghan Weed, Meghan Weed; Rainier Urdaneta, Harvard University; Serge Dibart, Boston University, Goldman School of Dental Medicine, Dept. Periodontology. This study was supported by Educational Grant Bicon LLC (Boston, MA).

• Background: Placement of short endosseous implants represents a valid tratment alternative to more complex surgical techniques such as ridge augmentation/sinus lift implant-associated procedures, in the setting of limited alveolar bone height. This study's objectives were: 1) to estimate the 5-year clinical survival of Bicon® 6x5.7mm implant 2) to evaluate radiographic bone level changes around 6x5.7mm implants in comparison with Bicon® longer non-6x5.7mm implants.
• Methods: A retrospective cohort study design was used. The cohort was composed of patients who had at least one 6x5.7mm implant placed for 5 years, at least one non-6x5.7mm implant, and who were willing to return to the dental office for radiographic evaluation. A total of 141 implants, 32 6x5.7mm (test group) and 109 non-6x5.7mm (control group), were placed in 20 patients (12 males and 8 females) with a mean age of 59.2 +/- 11.8 years. Mean length of non-6x5.7mm implants was 9.7 mm, (range: 8 mm to 14 mm, mean diameter was 4.39 mm (range: 3.5 mm to 5 mm). Bone loss, defined as the vertical difference in crestal bone level measurements from the baseline (day of implant placement) to 5 years follow-up, was digitally determined on periapical radiographs. Generalized linear mixed models were used for the statistical analysis.
• Results: Five-years survival rates for test and control groups were 90.3 % and 97.7% respectively, but this difference was not statistically significant (p>0.05). There was no significant difference between the two groups with regard to mean changes of radiographic bone levels.
• Conclusion: Short implants with large diameter (6x5.7mm) have a long-term (>5 years) survival rate and crestal bone level maintenance similar to that observed for non-6x5.7mm implants. The results of this radiographic study support the hypothesis that 6x5.7mm implants can be successfully used in edentulous maxillary and mandibular areas with limited bone height.

An integrated System for 3D Imaging, Implant Planning and Guided Implant Surgery

Lutz Ritter,* Surgical Systemes Laboratory; Timo Dreiseidler, Surgical Systemes Laboratory; Robert A. Mischkowski, Department of Craniomaxillofacial and Plastic Surgery, University of Cologne; Joerg Neugebauer, Department of Craniomaxillofacial and Plastic Surgery, University of Cologne; J.E. Zöller, Department of Craniomaxillofacial and Plastic Surgery, University of Cologne; Erwin Keeve; Surgical Systemes Laboratory

• Background: Today surgical drill guides based computer-aided dental implant planning are available but users have to handle several pieces of software, specific radiological protocols and data transfer from the radiologist. The aim of this study was to evaluate an integrated system for computer-aided implant planning consisting of a 3D cone beam scanner including software for planning and producing surgical drill guides.
• Methods: 25 patients were scanned using a novel cone beam scanner, producing a 3D dataset visualizing all relevant anatomy for implant planning. Patients were divided in two groups, for 13 patients in group A, a scan prosthesis indicating teeth to be replaced was applied for scanning and the scanner inherent software was used for implant planning and ordering of a CAD/CAM drill guide. 12 patients from group B were treated with a standard lab-fabricated drill guide worn during the scan and when necessary intraoperative adaptation of the implant position was performed.
• Results: 22 patients received 83 implants in the planed positions that were used for rehabilitation. 3 patients had to be augmented to provide a sufficient implant be. No anatomical complication as nerve injury has occurred. 2 out of 44 implants in group A showed minor deviations of the implant axis, being compensable by the use of standard angle abutments. 4 out of 39 implants in group B showed major deviation of the axis, requiring custom milled abutments. The planning process with the intuitive user interface for selecting the appropriate implant and its location took between 15 and 25 minutes. The drill guides were externally fabricated and returned after one week. Intraoperative handling of CAD/CAM and conventional drill guides was similar.
• Conclusion: Using CAD/CAM drill-guides shows to be precise and safe. It lets surgeons place implants exactly as planned, helps to avoid surgical complications, reduces costs for individual abutments and opens up possibilities for immediate prefabricated prosthetics. Compared to conventional planning the 3D-based computer aided planning approach facilitates documentation of implant planning and is helpful for patient education.

RESEARCH FORUM ORAL SESSION II
RISK ASSESSMENT, PREVENTION AND TREATMENT

Monday, September 18, 1:00–4:00 p.m.

Research contributor names, credentials, training institutions abstract content and abstract titles are listed below as provided by submitting author. In the list of authors for each abstract, an asterisk (*) indicates the presenting author at the Annual Meeting session.

Bioinformatic Prediction of Leader Genes in Human Periodontitis

Simone Marconcini,* D.D.S., Department of Oral Pathology and Medicine, School of Dental Medicine, University of Genova; Luca Giacomelli, Department of Oral Pathology and Medicine, School of Dental Medicine, University of Genova; Victor Sivozhelezov, Department of Oral Pathology and Medicine, School of Dental Medicine, University of Genova; Antonio Barone, Department of Oral Pathology and Medicine, School of Dental Medicine, University of Genova; Ugo Covani, Department of Oral Pathology and Medicine, School of Dental Medicine, University of Genova

• Background: A very large amount of genes is involved in each different biological process, but only few of them are actually the most important ones, i.e. the so-termed leader genes, as defined in previous bioinformatic and experimental studies concerning T lymphocyte cell cycle and osteogenesis (1-4). In this work, starting on the results of a more general bioinfomatic study on human inflammation (5), genes involved in human periodontitis are identified and ranked using different bioinformatic and datamining techniques, in order to identify the most important ones.
• Methods: Among the general inflammation gene set (5), composed of 341 genes, we identified a subset genes specifically involved in human periodontitis using a keyword-based query. This subset was then expanded by calculating direct protein-protein interactions using STRING database (6) and the results were filtered in order to avoid false positives. In the final set, the interactions among the genes are mapped and calculated according to the leader gene identification algorithm (1). We calculated, then, a combined score for each gene of the identified gene set, which is the weighed sum of every interactions in which the gene is involved. As last, we applied clustering methods to the combined association scores in order to rank genes and identify the group of leader genes, i.e. those with the highest number of interactions.
• Results: In total, we identify 61 genes specifically involved in periodontitis. Among all these genes, only 5 are invariably identified as leader genes, while other 12 are ranked in an immediately lower importance group, for a total of 17 genes with a significantly higher number of interactions, if compared to the rest of the gene set. It was interesting to notice that for 10 out of 17 genes there is evidence of involvement into the periodontitis process; 7 new genes involved in this disease are identified with this bioinformatic algorithm. Interestingly, among the 5 leader genes, the involvement of only 2 of them is known in periodonitis. Several metabolic pathways important in periodontitis were also recognized with this theoretical analysis.
• Conclusion: Specific molecular basis of periodontitits are still unclear. In this study, we applied a validated bioinformatic algorithm to increase our knowledge of molecular mechanisms of periodontitis. This theoretical analysis can suggest ad hoc experimentation, based on significant genes and therefore being simpler than mass scale molecular genomics. Moreover, with the identification of leader genes we can identify new promising therapeutic targets.

Positive Association of IL-1R2 with Aggressive Periodontitis in Japanese Population

Yuichi Ishihara,* D.D.S., Department of Periodontology, School of Dentistry, Aichi Gakuin University; H. Kamei, Department of Periodontology, School of Dentistry, Aichi Gakuin University; D. Fuma, Department of Periodontology, School of Dentistry, Aichi Gakuin University; M. Suzuki, Department of Periodontology, School of Dentistry, Aichi Gakuin University; T. Noguchi, Department of Periodontology, School of Dentistry, Aichi Gakuin University; T. Kojima, Human Genome Research Group, RIKEN Genomic Sciences Center, Yokohama, Japan. This study was supported by a "AGU High-Tech Research Center" Project for private Universities: matching fund subsidy, 2003-2007, and a grant to Aichi-gakuin University (16592082) and to RIKEN GSC from MEXT (the Japanese Ministry of Education, Culture, Sports, Science and Technology).

• Background: Aggressive periodontitis (AgP) is characterized by a rapid rate of periodontal tissue destruction in systemic healthy individuals. Genetic polymorphisms of the IL-1 gene cluster on chromosome 2 are thought to be associated with increased susceptibility to periodontitis. However, a positive association between the Type-2 IL-1 receptor gene (IL1R2) and periodontal disease has not yet been reported. Therefore, in this study, we investigated genetic polymorphisms in the IL1R1 and IL1R2 in the IL-1 gene cluster in Japanese population.
• Methods: A total of 102 Japanese patients and 88 periodontally healthy volunteers were recruited at the Department of Periodontology in Aichi-gakuin University from 2002 to 2004. The diagnostic criteria of AgP based on the age of onset of periodontitis less than 35 years, and attachment loss of 4mm or more on at least 4 permanent teeth, with at least one first molar affected. Written informed consent was obtained from all participants. Ethical committees of the School of Dentistry, Aichi-gakuin University and of the RIKEN YOKOHAMA INSTITUTE approved this study. Polymorphisms were identified by direct sequence method. After the single nucleotide polymorphisms (SNPs) identification, allelo- and haplotype analysis were performed.
• Results: A 14.5-kb genomic region containing all exons and relevant exon-intron boundaries of IL1R1 and IL1R2 were sequenced in 24 AgPs and 24 controls. Within genomic regions containing all exons and relevant exon-intron boundaries in IL1R1 and IL1R2, 38 SNPs were identified in 48 subjects. Five were located within coding elements, 2 in the 5' flanking region, 22 within introns, and 9 in the 3' untranslated region. Frequency of 3 SNPs and 3 haplotypes in IL1R2 showed significant differences between patients with AgP and controls (p<0.05).
• Conclusion: The results of this study suggested that the genetic susceptibility locus for AgP lies within or close to the IL1R2 locus and that allelic variations in IL1R2 may be useful genetic susceptibility markers for diagnosis, prevention, prognosis and treatment of AgP and may partly determine risk of periodontal disease.

Expression of Antimicrobial Peptides, IL-8, and Bone Morphogenetic Proteins by Gingival Epithelial Cells in Response to Various Oral Bacteria

Youngnim Choi,* D.D.S., School of Dentistry, Seoul National University; Youngsook Kim, School of Dentistry, Seoul National University; Suk Ji, School of Dentistry, Seoul National University

• Background: Gingival epithelia contact with plaque-forming bacteria continuously and initiate immune responses that may contribute to both defense to the bacteria and tissue destruction. To explore differences in the epithelial cell responses to commensal and periodontopathic bacteria, we analyzed the expressions of antimicrobial peptides, IL-8, and bone morphogenetic proteins by human oral keratinocytes in response to 9 oral bacterial species classified into non-periodontopathic, weak periodontopathic, and periodontopathic group.
• Methods: Three bacterial species for each group were used in this study: Streptococcus sanguinis, S. gordonii, Veillonella atypica for non-periodontopathic, Eikenella corrodens, Fusobacterium nucleatum, Prevotella intermedia for weak periodontopathic, and Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola for periodontopathic. HOK-16B cells, immortalized human oral keratinocytes derived from normal gingival epithelia, were plated and incubated g/ml bacterialovernight to allow adhesion. Then, cells were stimulated with 50 lysate in the presence of 2% human sera for 24 h. The expressions of LL-37, human beta defensins (HBD-1, -2, and -3) and bone morphogenetic proteins (BMP-2, and -4) were analyzed by real-time PCR and the amount of IL-8 accumulated in the supernatants was measured by ELISA.
• Results: Weak periodontopathic bacteria, especially F. nucleatum and P. intermedia, were the strongest inducers of antimicrobial peptides and IL-8. The secretion of IL-8 was suppressed by most other bacteria except T. forsythia. The regulation of BMP expression showed an opposite pattern: up-regulated by non-periodontopathic and periodontopathic bacteria but not by the weak periodontopathic group.
• Conclusion: Among the tested bacteria, F. nucleatum and P. intermedia were unique by highly up-regulating antimicrobial peptides and IL-8. It is interesting because those two bacteria were most susceptible to antimicrobial peptides and phagocytosis by neutrophils in our previous study. The role of the two bacteria in the pathogenesis of periodontitis may depend on biofilm formation through co-aggregating with diverse other bacteria.

Periodontopathic Bacteria are Resistant to Antimicrobial Peptides and Phagocytosis by Neutrophils

Suk Ji,* D.D.S., School of Dentistry and Dental Research Institute, Seoul National University; Youngnim Choi

• Background: Although ten to twenty out of hundreds of plaque-associated bacterial species are known as potentially periodontopathic, the nature of true periodontopathic bacteria remains to be answered. We hypothesized that non-periodontopathic bacteria are susceptible but periodontopathic ones are resistant to host defense.
• Methods: To address this issue, we studied 14 oral bacterial species 21 strains classified into non-periodontopathic, weak periodontopathic, and periodontopathic group for the susceptibility to phagocytosis by human neutrophils and antimicrobial peptides LL-37 and human beta defensin-3 (HBD-3). The MICs of LL-37 and HBD-3 were determined by a liquid dilution assay and phagocytic efficiency in the absence or presence of various opsonins was examined by a standardized flow cytometric phagocytosis assay.
• Results: Combined susceptibility to the antimicrobial peptides and phagocytosis in the absence of opsonins clearly characterized non-periodontopathic and periodontopathic groups as susceptible and resistant, respectively. The weak periodontopathic group showed a mixed characteristic. Pooled human IgG significantly increased the phagocytosis of most oral bacteria especially periodontopathic ones but some non-periodontopathic bacteria required both Ab and complement components for efficient phagocytosis. In addition, phagocytosis-sensitive bacteria served as opsonin probably through co-aggregation or the activation of neutrophils.
• Conclusion: In conclusion, we have shown that periodontopathic bacteria are resistant to both phagocytosis and antimicrobial peptides, which may provide new insights into the pathogenesis of periodontitis.

The Effect of Periodontal Diagnosis and Prognosis on the Survival of Prosthodontic Abutments: A Pilot Study

Leyvee Lynn Cabanilla,* D.D.S., University of Detroit Mercy; Flor Hernandez, University of Detroit Mercy; Anthony Neely, University of Detroit Mercy

• Background: The suitability of prosthodontic abutments is often made based on the periodontal diagnosis and prognosis. There is a lack of evidence regarding the true impact of periodontal diagnosis and prognosis on the survival of abutments. The purpose of this study was to determine if periodontal diagnosis and prognosis has an effect on the survival of prosthodontic abutments. The relationship of age, gender, ethnicity, smoking status and diabetes with the survival of prosthodontic abutments will be also presented.
• Methods: The study material consisted of 30 randomly selected patients with either fixed partial denture (FPD) or removable partial denture (RPD) made by Dental students at the University of Detroit Mercy School of Dentistry (UDMSD). All prostheses were delivered from 1992 to 2005. The following data were abstracted from dental charts: procedure performed, abutment tooth number, year of prosthesis delivery, year of most recent periodontal examination, year of tooth loss, patient information (age, gender, ethnicity, pertinent medical history, smoking status), periodontal diagnosis and prognosis (both overall and specific) at the time of prosthesis delivery and at the most recent periodontal examination (UDMSD IRB approval# 0304-28).
• Results: Subjects had a mean age of 66.13 +11.78 (range of 43-87) and 66.7% were female. Caucasians, African Americans and others comprised 36.7%, 53.3% and 10% of the population respectively. Smokers made up 13.3% while 43.3% were former smokers. Diabetes was found in 20%. Periodontal status showed 60% of the subjects had gingivitis, 26.7% had slight periodontitis, and 13.3% had moderate periodontitis. A good prognosis was seen for 76.7% of the population. Subjects had interim RPDs (37.9%), FPDs (34.5%) and RPDs (27.6%). Follow up of abutment teeth ranged from 3 to 166 months (mean of 38.3 + 39.66). Analysis showed 83.3% of the subjects lost no abutment teeth while 16.7% lost at least one tooth. No significant difference (p<0.05) in tooth loss was related to periodontal diagnosis, prognosis, age, ethnicity, gender, prosthesis, diabetes and smoking status using Chi- square analysis.
• Conclusion: In this pilot study of 30 patients with FPDs or RPDs, few abutment teeth were lost. Periodontal diagnosis, prognosis, age, ethnicity, gender, prosthesis, diabetes and smoking status were not significantly associated with abutment tooth loss. Most abutment teeth were lost by a few individuals. Anecdotally, most abutments were lost to caries and tooth fracture. Additional research is needed to identify variables that help predict abutment tooth loss over time. Future analysis of a larger sample size will include proportional hazards modeling analysis and regression analysis of tooth survival over time.

The effect of In Vitro Fertilization (IVF) Therapy on Periodontal Tissues
I. Clinical Findings

Anthodesmi Pavlatou,* D.D.S., Department of Periodontology, University of Athens; Alexandra Tsami, Department of Periodontology, University of Athens; Evdoxia Pepelasi, Department of Periodontology, University of Athens; William Papaioannou, Department of Preventive and Community Dentistry, University of Athens; Themis Mantzavinos, Ioannis Vrotsos and Zacharias Mantzavinos Department of Preventive and Community Dentistry, University of Athens

• Background: There are questions concerning the effect of sex hormones on periodontal tissues during In Vitro Fertilization (IVF); a technique that an increasing number of women are undertaking and which is characterized by the administration of large amounts of factors that stimulate production of large concentrations of estrogens and progesterone to produce large numbers of ova. The purpose of the present pilot study was to explore the possible effect of hormones administered for IVF therapy on the soft periodontal tissues.
• Methods: For this purpose a total of 19 women were studied. The patient selection criteria were: free medical history, no smoking, no hormone, antibiotic or antiseptic treatment for the last 12 months. Each woman was subjected to clinical examination prior to the initiation of the hormone administration for IVF (initial examination) and upon completion of the IVF program, when the pregnancy test was performed (final examination). Both at the initial and final examination the gingival index, plaque index and periodontal treatment needs index (CPITN) were evaluated. The estradiol levels were assessed at 4 consecutive times: at the initial examination, at the peak of the estradiol levels, upon ova collection and at the final examination. Furthermore, the number of produced ova and the number of inseminated ova were assessed for each woman.
• Results: The results of the present study revealed a small but not statistically significant increase for the gingival index upon completion of the IVF program. However, the gingival index increase was significantly correlated to the amount of gonadotrophins administered during IVF as well as to the final number of inseminated ova that were implanted in the uterus. There was no correlation between the elevated gingival index and the plaque index.
• Conclusion: The results of the present study indicate that the hormones administered for in vitro fertilization seem to affect the soft periodontal tissues. Further investigation is required to confirm these initial results.

The effect of In Vitro Fertilization (IVF) Therapy on Periodontal Tissues
II. Microbiological Results

Anthodesmi Pavlatou,* D.D.S., Department of Periodontology, University of Athens; Alexandra Tsami, Department of Periodontology, University of Athens; William Papaioannou, Department of Preventive and Community Dentistry, University of Athens; Marc Quirynen, Evdoxia Pepelasi, Themis Mantzavinos, Ioannis Vrotsos and Zacharias Mantzavinos Department of Preventive and Community Dentistry, University of Athens; Anne Haffajee, Department of Periodontology, Forsyth Institute

• Background: There are questions concerning the effect of sex hormones on periodontal tissues during In Vitro Fertilization(IVF); a technique that an increasing number of women are undertaking and which is characterized by the administration of large amounts of factors that stimulate production of large concentrations of estrogens and progesterone to produce large numbers of ova. The present pilot study was designed to investigate the possible changes in the subgingival flora that may occur due to the effect of increased hormonal levels in women undergoing IVF therapy.
• Methods: 19 women of reproductive age (≤45 years), who were to begin IVF were selected based on their having good general health, and no use of antibiotics, hormonal or other medicines during the last 6 months. A complete periodontal examination and subgingival plaque sampling were performed at the start as well as after completion of the IVF program. Two pooled subgingival plaque samples were collected from selected teeth based on probing depth; 4 sites (one per quadrant) with the greatest depth (representing diseased periodontium) and 4 sites (one per quadrant) with the smallest depth (representing healthy periodontium). Samples were obtained using paper-points that were placed in the respective pockets for 10 seconds. The qualitative and quantitative examination of the subgingival flora was performed using DNA probes and the Checkerboard technique.
• Results: The subgingival plaque collected from the deepest pockets after IVF showed a significant shift in the red bacteria group (significant correlation with the gingival index (p<0.05)), as well as significant changes in the actino, yellow and green groups (significant correlation with the type of IVF protocol (p<0.01)). The changes in the actino and yellow in these pockets also correlated significantly with blood estradiol levels (p<0.01 and p<0.05, respectively),while the number of ova correlated (p<0.05) with changes in the yellow and green groups. Microbial changes in the shallow pockets after IVF concerned significant shifts in the orange, red, actino, yellow and green groups which correlated significantly with blood estradiol levels (p<0.05).
• Conclusion: From the analysis of all periodontopathogens it was determined that their quantitative changes were significantly correlated to the protocol used in IVF therapy as well as the estradiol levels after the administration of gonadotrophins. These significant changes concerned the deep as well as the shallow pockets, although to a different degree.

Conebeam CT Precision in Alveolar Bone Density Measurement

Pirkka V. Nummikoski,* D.D.S., University of Texas Health Science Center at San Antonio

• Background: Radiographic follow-up of bone healing after grafting is challenging because of the overlapping of gaining and losing areas within the graft. The new volumetric imaging method, cone beam computed tomography (CBCT), offers an opportunity to see inside the bone, and pinpoint and measure densities in small localized areas such as a vertical periodontal defect, or an alveolar bone graft. This study was carried out to assess the reproducibility (precision) of bone density measurement in the alveolar bone using high-resolution CBCT imaging.
• Methods: 3D Accuitomo CT was used in the imaging of 26 patients. The scanning was completed twice at separate appointments. Prior to scanning, a bone density device containing 3 blocks (each 4x4x4mm) of different known tissue densities, was positioned between the tongue and the alveolus. The repeated image volumes were registered globally using 3-D Voxel Registration (Analyze 6.0; Mayo Clinic). The voxel densities of the reference blocks were measured and plotted against the known tissue densities. The average voxel value of two different size volumes were measured in the baseline and follow-up scans. Obtained voxel densities were transformed into bone densities using the fitted equation calculated for each scan. The precision was defined as the pooled standard deviation of the duplicate measurements, and described as coefficient of variation (C.V.).
• Results: 32 paired scans were acquired. Overall precision (repeatability) of density measurements in the alveolar bone area was (C.V.) = 9.6%. For large size volumes (Mean±SD; 68±11mm3) the C.V. was 9.0%, and for smaller volumes (12.3±1.6mm3) C.V. was 10.6%. It was discovered that, if the density reference device was not in a similar location in the follow-up scan, the measurement discrepancy was large. Therefore, the data was re-analyzed using only the scans where the reference blocks were in similar location. In this data set of 24 scan pairs, the precision for larger volume measurements was 6.1% and for smaller volumes was 9.7%. The C.V. of the measurements done using the original, untransformed, voxels values of the scan was 41.5%.
• Conclusion: The study revealed that density measurements done using the original voxel values of the scans have a very high variability, and therefore are useless in density assessment. However, using a scanning protocol with an intraoral density reference device and well-standardized techniques, resulted in a much better precision of 6 to 9%. This precision would make it possible to reproducibly quantify the bone remodeling following bone grafting.

Periodontal Treatment Improve the Systemic CRP and Pro-inflammatory Cytokine Levels

Kazuhisa Yamazaki,* D.D.S., Niigata University Faculty of Dentistry; Tomoyuki Honda; Niigata University Graduate School of Medical and Dental Sciences; Takafumi Okui, Niigata University Graduate School of Medical and Dental Sciences; Keiko Kajita, Niigata University Graduate School of Medical and Dental Sciences; Hisanori Domon, Niigata University Graduate School of Medical and Dental Sciences; Takako Nakajima; Niigata University Medical and Dental Hospital. This studay was supported by Grant-in Aids for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (16390613, 16592066).

• Background: Growing evidence of animal and population-based studies has demonstrated an association between periodontal disease and cardiovascular disease (CVD). Although several potential mechanisms have been postulated, the mechanism by which periodontal infection associate with CVD is still unclear. The aim of this study is to examine whether periodontal treatment has influence on serological markers of systemic inflammation in Japanese population.
• Methods: Sera were obtained from 50 Japanese patients with periodontitis at the baseline examination and at reassessment after completion of periodontal treatment. hs-CRP was measured using nephelometry with a latex particle-enhanced immunoassay and IL-6 and TNF-α were determined by sensitive enzyme-linked immunosorbent assay.
• Results: Periodontal examination demonstrated that probing pocket depth and clinical attachment level were significantly improved following treatment. After periodontal treatment, significant decrease in the levels of hs-CRP and IL-6 was observed (median of hsCRP; 352ng/ml to 346ng/ml, p<0.01, median of IL-6; 0.673pg/ml to 0.579pg/ml, p<0.05). The levels of TNF-α, however, did not show significant difference between baseline and reassessment.
• Conclusion: These data suggest that infection derived periodontal inflammation could be a risk factor for atherosclerosis, and periodontal treatment may improve the levels of systemic inflammatory markers.

Quadrant Root Planing Versus Same-Day Full-Mouth Root Planing With and Without Chlorhexidine

Katrin Swierkot,* Dental School of Medicine, Marburg, Germany; Lavin Flores-de-Jacoby, Dental School of Medicine, Marburg, Germany; Reiner Mengel, Dental School of Medicine, Marburg, Germany

• Background: The aim of this study was to test the hypothesis that the one-stage full-mouth disinfection (FMD) resulted in greater clinical improvement compared to same-day full-mouth scaling and root planing (FM-SRP) and quadrant scaling and root planing (Q-SRP) in chronic periodontitis patients over a period of 8 months.
• Methods: 28 patients with untreated chronic periodontitis were randomised into three groups. The control group (Q-SRP) was scaled and root planed quadrant per quadrant at one-week intervals for four consecutive sessions. The two other groups received a one-stage full-mouth scaling and root planing (all pockets within 24h) with (FMD) and without (FM-SRP) the adjunctive use of chlorhexidine. At baseline and after 1, 2, 4 and 8 months clinical parameters were recorded and microbiological samples from the deepest site of each quadrant were taken and in addition after 24h. The number of A. actinomycetemcomitans, P. gingivalis, P. intermedia, P. micros, D. pneumosintes, F. nucleatum, C. gingivalis and C. rectus and total bacteria were quantified with Real-time PCR.
• Results: The FM-SRP group showed significant differences in PD reduction after 2 months compared to the Q-SRP group (p = 0,045). This could also be shown for medium pockets (4 - 6 mm) of the multi-rooted teeth (p = 0,025). Significant improvements in the other clinical indices could not be revealed in any group. All three treatment modalities resulted in significant reduction of the total bacteria over a period of 8 months and reached peak levels after 4 months. There were significant reductions in the number of P. intermedia in FM-SRP patients compared to the other two groups (p ≤ 0,003). FMD doesn't show advantages in comparison to the other groups.
• Conclusion: In conclusion, all three treatment modalities revealed clinical improvements and led to a significant reduction of bacteria.

Comparing the Efficacy of Two Mouth Rinses in Reducing Bacterial Aerosol Contamination

Dharmarajan Gopalakrishnan,* M.D.S., IOMIT' S SSR Medical College, Mauritius; Vidya Gopalakrishnan, IOMIT' S SSR Medical College, Mauritius; Abbasakoor A.R. Esmail, Superintending Dental Surgeon, Ministry Of Health, Mauritius; Raj Sungker, Ministry Of Health, Mauritius; D.S.Vijayanarayanan, Tamilnadu, India

• Background: Cross–Contamination from microbial aerosols produced during dental procedures is of great concern.The purpose of this study was to compare bacterial aerosol contamination generated by ultrasonic scalers following two consecutive 30-second rinses with chlorhexidine gluconate (0.12% w/v)(Hex) and a mouthrinse containing cetylpyrinidinium chloride (0.5% w/v) and sodium fluoride (0.05% w/v)(CPC).
• Methods: 36 subjects free from any systemic disease (18 males, 18 females; aged 18 to 45 years) with moderate to severe forms of gingivitis were included in the study. They were divided into 2 groups of 15 each; one group rinsed with Hex while the other rinsed with CPC. Blood agar plates were placed uncovered in eight standardized locations to determine aerosols during the experimental procedure. The subjects of each group were instructed to rinse for two consecutive 30-second periods before ultrasonic scaling. The blood agar plates were collected at different time intervals (without rinsing before scaling, after rinsing before scaling and 30 minutes after scaling) to assess the aerosol contamination. After each sampling, the plates were incubated in an increased CO2 chamber for 48 hours in order to assess colony-forming units at each interval.
• Results: Results of this study showed that both groups had demonstrated reduced colony forming units at all eight locations after rinsing as compared prior to rinsing. The group that had rinsed with chlorhexidine gluconate had significantly reduced colony-forming units when compared with the group that had rinsed with a mouthrinse containing cetylpyridinium chloride and sodium fluoride [P < 0.001].
• Conclusion: The above study suggests that pre-procedural rinsing with chorhexidine had significantly reduced bacterial aerosol contamination when compared to rinsing with cetylpyridinium chloride & sodium fluoride. It also demonstrates that aerosol contamination remains a significant hazard to dental personnel.

Gingival Recession Treatment with Connective Tissue Grafts in Smokers and Non-Smokers

Kenneth J. Erley,* D.M.D., U.S. Army Periodontic Residency Program, Fort Gordon; Gary D. Swiec, U.S. Army Periodontic Residency Program, Fort Gordon; Robert W. Herold, U.S. Army Periodontic Residency Program, Fort Gordon; Frederick C. Bisch, U.S. Army Periodontic Residency Program, Fort Gordon; Mark E. Peacock, U.S. Army Europe, Landstuhl

• Background: The effect of cigarette smoking adversely effects wound healing in many surgical procedures. The purpose of this study was to determine if cigarette smoking had any effects on subepithelial connective tissue graft wound healing in the oral cavity.
• Methods: 17 systemically healthy patients with 22 Miller Class I or II mucogingival defects were placed into a non-smoker group or smoker group. Patients were regarded as smokers if they reported smoking over 10-20 cigarettes a day. The following parameters were documented at surgery date, 3 months and 6 months: relative attachment level, recession depth, recession width, keratinized gingiva height, probing depths, the presence of bleeding on probing and a full-mouth plaque score. Salivary cotinine samples were taken at the surgery date to confirm the health history and to quantify cigarette consumption.
• Results: Non-smokers (0-10 ng/ml cotinine level) healed with 98.6% Root Coverage, 97.2% Defect Fill, and 3.2 mm KG increase. Light Smokers (10-40 ng/ml cotinine level) healed with 94.5% Root Coverage, 89.1% Defect Fill and 2.1 mm KG increase. Heavy smokers (>40ng/ml cotinine levels) healed with 90.3 % Root Coverage, 75.8% Defect Fill and 1.9 mm KG increase. Defect Fill was significant at the (P<0.0011) between the smokers and no-smokers. No difference was noted in other parameters measured.
• Conclusion: Root Coverage, defect fill and keratinized gingiva appear to be negatively associated with the number of cigarettes smoked in patients treated with connective tissue grafts. Smokers healed with significantly less coverage the root surface.

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