Copyright © 2015 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited. et al 7 demonstrated that the a2 adrenergic receptors activates the extracellular signal-regulated kinase pathway and stimulates the proliferation of epithelial cells derived from the proximal renal tubule of rat and pig. The study showed that systemic administration of a2 agonists stimulate the proliferation of epithelial cells derived from the proximal renal tubule and modulate regeneration of tubular cells. Although dexmedetomidine is a2 agonists, in the current study we found similar proliferative effect of dexmedetomidine on nasal mucosal tissue in rats via IN and IP administrations as compared with IN saline usage. Iirola et al 8 demonstrated that dexmedetomidine is rather rapidly and efficiently absorbed after IN administration. Compared with intravenous administration, IN administration may be a feasible alternative in patients requiring light sedation. Their study also indicates high bioavailability of IN usage of dexmedetomi- dine. The strength of our study is the assessment of cytotoxicity of IN dexmedetomidine for the first time. However, usage of one staining method was the limiting point of the study. The results presented are preliminary and the literature concerning this issue is poor. As a result the current study showed that IN administration of dexme- detomidine has not any additional proliferative effect as compared with IN saline. Further studies are needed to support the conven- ience and safety of this drug. Fatih Oghan, MD Isa Ozbay, MD Cuneyt Kucur, MD Department of Otorhinolaryngology Dumlupinar University Medical Faculty Kutahya, Turkey fatihoghan@hotmail.com Bahadir Baykal, MD Department of ORL Bakirkoy Sadi Konuk Education and Research Hospital Istanbul, Turkey Muhammet Kasim Cayci, PhD Department of Biology Dumlupinar University Kutahya, Turkey Mehmet Esref Kabalar, MD Department of Pathology Erzurum Region Education and Research Hospital Erzurum, Turkey Ayse Nur Deger, MD Department of Pathology Dumlupinar University Kutahya, Turkey REFERENCES 1. Gertler R, Brown HC, Mitchell DH, et al. Dexmedetomidine: a novel sedative-analgesic agent. BUMC Proc 2001;14:13–21 2. Hayashi Y, Maze M. Alpha 2 adrenoceptor agonists and anaesthesia. Br J Anaesth 1993;71:108–118 3. Yuen VM, Irwin MG, Hui TW, et al. A double blind, crossover assessment of the sedative and analgesic effects of intranasal dexmedetomidine. Anesth Analg 2007;105:374–380 4. Sayani AP, Chien YW. Systemic delivery of peptides and proteins across absorptive mucosa. Crit Rev Ther Drug Carrier Syst 1996;13: 85–184 5. Oghan F, Apuhan T, Terzi H, et al. Cytotoxic effects of nasal buserelin on nasal mucosal tissue in rabbits. Eur Arch Otorhinolaryngol 2012;269: 1771–1776 6. Michel MC, Rump LC. Alpha-adrenergic regulation of human renal function. Fundam Clin Pharmacol 1996;10:493–503 7. Cussac D, Schaak S, Gales C, et al. alpha2B-Adrenergic receptors activate MAPK and modulate proliferation of primary cultured proximal tubule cells. Am J Physiol Renal Physiol 2002;282:F943–F952 8. Iirola T, Vilo S, Manner T, et al. Bioavailability of dexmedetomidine after intranasal administration. Eur J Clin Pharmacol 2011;67: 825–831 Dental Implant Placement in Patients With Osteoporosis To the Editor: Even though dental implants have a high rate of success on long term, failures are still present. There are some risk factors associated with dental implant failures, such as: smoking, radiotherapy, diabetes, and osteoporosis. 1,2 Especially, osteoporosis has been subjected to controversy about its importance and effects on dental therapy outcomes. Using dental implants for patients with osteoporosis is still debated in dental literature 3 because of quality of local bone, which is a key factor that determines success of dental implant 4 and because of effect of bisphosphonates used in treatment of osteoporosis that could induce osteonecrosis of the jaws. 5 Osteoporosis is recognized as a common skeletal disorder characterized by reduced bone mass and modification of bone architecture, which leads to increased bone fragility and increased fracture risk. 6 This condition is associated with a decrease in bone quality and quantity and successful dental implant osseointegration depends partially on the recipient site. 7 Furthermore, low bone mineral density and consequently bone loss is significantly associ- ated with periodontitis. 8 There are relatively few clinical studies that report outcomes of dental implant treatments in patients with osteoporosis and relation- ship between osteoporosis therapy and outcomes of endosseous implant treatments. The aim of this study is to assess osseointegration of dental implant in bone with low density. A total of 573 implants were placed for subjects with total or partially maxillary edentulism; 341 implants for subjects (group A) with osteoporosis, and 232 for subjects without osteoporosis (group B). All subjects required bone augmentation techniques. For all subjects, bone density was assessed pre- and postoperatively at 12 months. In both groups, women are prevalent: 92.59% in group A and 83.72% in group B. Main cause of tooth loss is periodontitis (61.11%) in group A, when in group B, there is a balance between periodontitis (41.86%) and caries (44.18%). There is a statistically higher association between osteoporosis and periodontitis. The frequency of complete edentu- lism was similar 31.48% in group A and 30.23% in group B. The mean number of implants per subject is 6.31 in group A and 5.39 in group B. Failure appeared for 27.78% subjects and 7.33% implants in group A and for 6.98% subjects and 2.59% implants in group B and is related with achieving initial stability. The rate of failure is statistically higher for group A, but there is a significant statistically association between strontium ranelate and low rate of implant failure for subjects with osteoporosis. According to our findings in this study, it is reasonable to place endosseous implants with bone augmentation in subjects with Correspondence The Journal of Craniofacial Surgery  Volume 26, Number 6, September 2015 e558 # 2015 Mutaz B. Habal, MD