Craniofacial Reconstruction and Aging of Human Mesenchymal Stem Cells

Oral Abstract Session 4 method or the distraction osteogenesis has been selected. In the bone grafting method, there is a problem of bone resorption. In the distraction osteogenesis, there is a difficulty of making the transport segment. The method of doing both the bone grafting and the distraction osteogenesis simultaneously has not been reported. If both methods could be done simultaneously, those problems might be able to be solved. The purpose of this research is to do the immediate distraction osteogenesis with bone grafting for the mandible in dogs. Materials and Methods: All animal experiments were conducted according to the Guidelines for Animal Experimentation at Kyushu Dental College, Japan. Ten beagle dogs were used in this experiment. The right side was the immediate distraction osteogenesis side (IDO). The left side was augmented by the bone grafting method (BG). Mandibular premolars were extracted and buccal corticotomy performed in each dog, and alveolar defect models were created. The cortical bone block of 2 mm in thickness was made from the same side of the mandible. The block bone was transplanted to the alveolar defect region, and a horizontal alveoler distraction device (Alveo-Wider) was installed. After a 10-day latency period of soft tissue restoration, distraction commenced at a rate of 0.2 mm per day for 10 consecutive days to allow for horizontal elongation of 2.0 mm at the top of crest. Immediately after the distraction osteogenesis, the left mandibular premolars were extracted and the cortical bone block was transplanted to the region. The dogs were sacrificed 1 month (1m group; n⫽5) or 3 months (3m group; n⫽5) after the bone augmentation. Method of Data Analysis: Amounts of bone augmentation were compared by means of Student t tests. Results: Bone augmentation: 1 m group; The amount of bone augmentation was 3.6 mm in IDO and was 1.6 mm in BG. 3 m group; the amount of bone augmentation was 2.6 mm in IDO and was 1.4 mm in BG. Histomorphology: New bone formation could be seen in the distraction gap 1 month after the bone augmentation. 3 months after bone augmentation, a mature bone tissue was admitted in the distraction gap, although the transport segment was almost absorbed. Conclusion: The amount of the bone augmentation in IDO was more than that in BG. IDO reported on this experiment seemed one of useful bone augmentation methods.

Craniofacial Reconstruction and Aging of Human Mesenchymal Stem Cells Robert J. Gassner, MD, DMD, PhD, Department of Cranio-Maxillofacial Surgery, Medical University of Innsbruck, Maximilianstrasse 10, University Hospital of Innsbruck, Innsbruck, 6020, Austria (Kloss F; Rasse M; Fehrer C; Brunauer R; Laschober G; Unterluggauer H; Gu ¨ lly C; Reitinger S; Lepperdinger G) Statement: Corrective surgery of craniofacial anomalies often requires bone harvesting and transplantation. The aim of this study was to assess biopsies from iliac crests of differently aged human donors for the presence of mesenchymal stem cells (MSC). MSC are self-renewing entities while generating multipotential progeny. Therefore, this class of cells is of paramount importance for bone repair and bone healing. We studied MSC aging and provide evidence that besides the individual age of the cell, stem and progenitor cell functions are influenced by the cellular environment. Materials and Methods: Biopsies from iliac crests were digested to collect MSC. Mesenchymal progenitor cells were isolated from spongious bone biopsies. Due to a ten-fold higher cell number from the tight meshwork of the surface of trabecular bone after collagenase treatment than from surrounding marrow mesenchymal progenitor cells in bone different oxygen tensions of 3 and 20% were evaluated. Method of Data Analysis: Primary colony forming units, growth rates during long-term culture, senescent marker expression, in vitro differentiation capacity into osteogenic and adipogenic lineage as well as expression profiles employing whole genome arrays were determined using standard procedures. Results: Oxygen levels appeared to effectively influence the respective differentiation potential of cultured MSC. While high oxygen tension was supporting osteogenesis and adipogenesis, hypoxia greatly inhibited celluar differentiation into the osteogenic lineage. Moreover, the onset of growth arrest was found to be delayed under reduced oxygen levels. Conclusion: Taking these results together, the efficacy of corrective surgery of craniofacial anomalies using bone transplantation, tissue engineering applications and regenerative technologies is dependent on the age of MSC. In particular, we have experienced that MSC are sensitive to oxidative stress, a fact which, we believe, is relevant for clinical therapy.

References

References

Nosaka Y, Kitano S. Wada K, Komori T. Endosseous implants in horizontal alveolar ridge distraction osteogenesis. Int J Oral Maxillofac Implants 2002; 17:846-853 Takahashi, T, Funaki K, Shintani H, Haruoka T. Use of Horizontal Alveolar Distraction Osteogenesis for Implant Placement in a Narrow Alveolar Ridge: A Case Report. Int J Oral Maxillofac Implants 2004 19-2; 291-294

Kloss F, Gassner R (2006): Bone and Aging: Effects on the maxillofacial skeleton. Invited Mini-Review. Experimental Gerontology 41: 123-129 Steinmueller-Nethl D, Kloss F, Najam-Ul-Haq M, Rainer M, Larson K, Linsmeier C, Koehler G, Gassner R, Huck C, Lepperdinger G, Bonn G (2006): Physisorption of BMP-2 on nanocrystalline diamond retains bioactivity. Biomaterials 27: 4547-4556

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AAOMS • 2007

Oral Abstract Session 4 Halaschek-Wiener J, Brooks-Wilson A (2007): Progeria of stem cells: stem cell exhaustion in hutchinson-gilford progeria syndrome. J Gerontol A Biol Sci Med Sci 62:3-8

A Retrospective Review of the Types of Chronic Sialadenitis Encountered and Outcomes of Sialoendoscopic Treatment at New York University/Bellevue Hospital Michael D. Turner, DDS, MD, New York University College of Dentistry, Department of Oral and Maxillofacial Surgery, 345 E 24th Street, New York, NY 11375 (Glickman RS) Statement: There are many potential factors that can initiate and propagate recurrent sialadenitis. The primary initiating factor of sialadenitis is either a decrease, or a complete cessation, of salivary flow. Salivary stagnation allows a retrograde bacterial migration of the oral flora into the sterile gland, initiating an immune and inflammatory response, termed bacterial sialadenitis. The inflammation causes damage to the epithelium and fibrotic tissue formation causing adhesions and strictures. Partial obstruction of the gland is gradually followed by salivary retention and duct dilatation, leading to recurrent infections and propagation of adhesion formation. This ultimately leads to a continuous sialostasis. The continual inflammation causes a necrosis of the acinar cells in addition to the proliferated fibrotic process. The avascular environment leads to a transformation of the bacterial flora from predominant aerobic gram positive cocci to a combination of anaerobic bacilli and peptostreptococcus (Brook, 2002). Materials and Methods: Sialoendoscopy has been used in the management of obstructive sialadenitis since 1990. Depending on the etiology of the sialadenitis, it has had a significant high success rate with a very low morbidity and recurrence rate. Although the treatment of chronic sialadenitis still remains a difficult disease to manage, the treatment modality of sialoendoscopy allows for a combination of treatment, including removal of sialolith, lysis of adhesions and other ductal obstructions, irrigation of infected regions, removal of necrotic tissue, creation of a patent ductal system, under direct visualization (Nahlieli et al, 2006). Method of Data Analysis: A retrospective case analysis was performed, dividing the data by eitiology, short term success, long term success, and type of anesthesia. Each area was evaluated individually. Results: In the thirty patients we have treated over the past 36 months at our facilities, can be divided into three distinct diagnoses based upon etiological cause: Chronic Sialadenitis Secondary to Sialolithiasis (CSL) (N⫽16), Chronic Sialadenitis Secondary to Stricture Formation (CSS) (N⫽12), and Juvenile Recurrent Parotitis (JRP) AAOMS • 2007

(N⫽2). The criterion of success used was divided into two categories, short term and long term. Short term success was defined as a resolution of symptoms 30 days following endoscopy. Long term is defined by resolution 1 year and longer following surgery. Our overall short term success rate for CSS was (15/16) 94%, with a long term success rate of 81% (13/16). Short term success rate for CSL was (10/12) 83%. Percentages for long term follow up are not relevant because either the stone was removed or it was not. One case that was performed as an open surgical procedure as sialoendoscopic assist case was not performed by the author and is classified as a failure. Of the JRP cases (N⫽2), one was symptom free at one year and one relapsed four months later and is scheduled for surgery. Conclusion: Of interest, in comparing cases performed under local anesthesia/sedation, in an office setting versus general anesthesia in the operating room, the local/sedation cases were successful (short and long term) 60% (6/10) and the general anesthetic cases were successful (short and long term) 90% (18/20). Although no statistically significant conclusions can be drawn from this data, it does appear that an association between the type of anesthesia and the success rate can be inferred in our experience. As case numbers increase, this variable needs to be monitored for significance. References Brook I (2002). Aerobic and anaerobic microbiology of suppurative sialadenitis. J Med Microbiol 51(6):526-9 Nahlieli O, Nakar LH, Nazarian Y, Turner MD (2006). Sialoendoscopy: A new approach to salivary gland obstructive pathology. J Am Dent Assoc 137(10):1394-400

Retrospective Review of Odontogenic Infections at a Tertiary Medical Center: Clinical Correlations Based on Culture and Sensitivity Data Armond Kotikian, DDS, MD, University of Michigan, Section of Oral and Maxillofacial Surgery, 1500 Medical Center Drive, Room B1222, Ann Arbor, MI 48109 (Kotikian A; Edwards S; Le T) Statement: Odontogenic infections are a significant source of morbidity. Cultures from these infections have shown a greater incidence of nosocomial microbes presenting as community acquired infections. These microbes have a greater propensity toward resistance to traditional empiric antibiotic choices. This is a review of our experience with resistance patterns of odontogenic infections presenting to our tertiary academic medical center over the past 5 years. Materials and Methods: This study is a retrospective review of 92 patients with odontogenic infections deemed severe enough to require incision and drainage in the operating room setting. These patients presented 36.e4