Journal of Oral Implantology April 2013 - (Page 234)

LETTER TO THE EDITOR Dear Editor, I would like to highlight a few key aspects of Ohno and colleagues1 excellent paper published in this issue of Journal of Oral Implantology (JOI) and thank the authors from Kanagawa Dental College for their collaboration and outstanding work. The article focuses on using OsteoGen crystals coated with a biomimetic nano-crystalline fluorapatite surface technology to promote osteoblast cell differentiation, migration, and proliferation, which are expected to accelerate bone growth; a finding supported by our own and a related researcher’s histologic findings.2 The paper established increased physiologic bioactivity for bone mineralization due to the unique fluorapatite nano-crystalline surface coating. Increased levels of the osteogenic differentiation marker, alkaline phosphatase (ALP), demonstrated this physiologic bioactivity. Osteoblast cell recruitment is also true, but to a lesser degree, with the original nonfluoridated OsteoGen crystals and clusters.3–5 Ohno and colleagues’1 paper (Figure 2a, the control noncoated crystals) confirms that OsteoGen is chemotactic with ;6 to 7 osteoblast cells in the field of microscopic view. This control is compared to the experiment (Ohno et al1, Figure 2b) having fluorapatite coated crystals showing ;18 to 21 osteoblast cells, or an improvement of 300% to accelerate osteoblast cell recruitment and proliferation for the purpose of laying down new bone formation. I would like to thank JOI for the opportunity to clarify some misconceptions regarding the differences between nonresorbing dense filler granules classified as ceramics (eg, hydroxylapatite [HA], tricalcium phosphate [TCP], bovine, coralline, glass, and plastics) and nonceramic synthetic bioactive resorbable HA crystals. Physicochemically ceramic grafts are distinctively different from OsteoGen grafts. OsteoGen nonceramic crystals are not sintered like ceramics. By avoiding high temperatures associated with ceramics, the material does not lose its natural state [Ca5(PO4)3(OH)] and retains physicochemical properties similar to human trabecular bone.3,4,6 DOI: 10.1563/AAID-JOI-D-Letter.3902 234 Vol. XXXIX /No. Two / 2013 Similarities exist between nonceramic OsteoGen crystals and human bone mineral as the two have the same formulation and crystallographic structure for HA, as defined by the International Center for Diffraction Data. Ceramic granules [CA 1 0 (PO4)6(OH)2], including bovine ceramics, dehydroxylate under high heat sintering and convert to oxyapatite [Ca10(PO4)6O2], losing their hydroxyl and calcium carbonate groups.7,8 Ceramic HA is not truly an HA and these ceramic granules are dissimilar to OsteoGen crystals or biological bone, as evidenced by infrared spectroscopy and X-ray diffraction.4 Nonresorbable dense and monolithic particulates are mostly removed by macrophages and giant cells through fragmentation. This could result in passage of these particles to the regional lymph nodes, lungs, and spleen for further processing, and therefore, interfering with the normal function of these organs and possibly compromise the immune system.9,10 Artzi and colleagues’ clinical study9 reports that ‘‘OsteoGen is physiochemically and crystallographically equivalent to human bone,’’ and the ‘‘threedimensional configuration of OsteoGen (crystal clusters) provides more space between particles when compared to ceramics. These spaces facilitate cellular and tissue proliferation into the grafted material, thus enhancing osseointegration.’’ Reference is made to the Sinus Consensus Conference11 where Artzi et al5 clarifies that ‘‘what is important is the implant success rate over time (3 to 5 years).’’ Fifteen papers have reported on the safety, effectiveness, and over 5 year cumulative 98% success rate of OsteoGen.12 In conclusion, as Ohno et al1 have demonstrated: nonceramic OsteoGen crystals coated with a biomimetic nano-crystalline fluorapatite surface technology promote osteoblast cell differentiation, migration, and proliferation, which is expected to accelerate bone formation. This reaffirms the work of previous investigators.2 Beyond these benefits, the microfine nano-crystalline fluorapatite coating, both loosely and firmly bound on the nonceramic OsteoGen crystal surface provides a time-release mechanism of having a bioactive barrier resulting in the creation of a bacteriostatic state. This bacterio-

Table of Contents for the Digital Edition of Journal of Oral Implantology April 2013

Evidence-Based Practice or Practice-Based Evidence?
Evaluation of Optimal Taper of Immediately Loaded Wide-Diameter Implants: A Finite Element Analysis
A Prospective, Randomized Controlled Preclinical Trial to Evaluate Different Formulations of Biphasic Calcium Phosphate in Combination With a Hydroxyapatite Collagen Membrane to Reconstruct Deficient Alveolar Ridges
Retention of Implant-Supported Overdenture With Bar/Clip and Stud Attachment Designs
The Clinical and Histologic Outcome of Dental Implant in Large Ridge Defect Regenerated With Alloplast: A Randomized Controlled Preclinical Trial
Fluoride-Treated Bio-Resorbable Synthetic Hydroxyapatite Promotes Proliferation and Differentiation of Human Osteoblastic MG-63 Cells
Resonance Frequency Analysis of 208 Straumann Dental Implants During the Healing Period
A Simplified Technique for Solving the Transfer Problem of Implant-Supported Fixed Partial Dentures for Patients With Microstomia
Esthetic Evaluation of Single-Tooth Morse Taper Connection Implants Placed in Fresh Extraction Sockets or Healed Sites
A Technique for Improving the Retention of Dentures Retained by Ramus Frame Implants
Treatment of Congenitally Missing Maxillary Lateral Incisors: An Interdisciplinary Approach
Use of Titanium Mesh in Lieu of a Fixation Screw to Stabilize an Autogenous Block Graft: A Case Report
A Novel Approach to Preserve the Buccal Wall in Immediate Implant Cases: A Clinical Report
Implant Failure Associated With Actinomycosis in a Medically Compromised Patient
Replacement of Mandibular Posterior Teeth With Implants in a Postmandibular Resection Case: A Case Report
Zygomatic Implants/Fixture: A Systematic Review
An Overview of Immediate Root Analogue Zirconia Implants
Letter to the Editor
Reviews of Current Literature

Journal of Oral Implantology April 2013