Introduction: floating teeth is a condition when teeth lose their supporting alveolar bone as a result of a destructive process, which is most frequently occur in the molar/ premolar region of both jaws. The aim of this study was to review the common conditions associated with floating teeth. Materials and methods: We used general search engines and specialized databases including Google Scholar, Pub Med, Pub Med Central, Science Direct, and Scopus to find relevant studies by using keywords such as "jaw lesion", "jaw disease", "floating tooth", “, floating teeth”, , "tooth mobility", and “, tooth loss”, . About 100 articles were found, of which approximately 80 were broadly relevant to the topic, and finally 30 articles closely related to the above topic were chosen. Results: When the data were compiled, the following 9 lesions were found to have more relationship with floating teeth appearance: Aggressive periodontitis, Langerhans histiocytosis, Burkitt’, s lymphoma, multiple myeloma, Metastatic tumors, Primary intraosseous carcinoma (intraosseous squamous cell carcinoma), Ewing’, s sarcoma, Hyperparathyroidism, and Cherubism. Conclusion: When clinicians encounter a lesion associated with floating teeth, they should consider these entities especially malignant disorders in differential diagnosis to make more accurate diagnoses and develop better treatment plans according to patients' imagings.

Background and Aims: Caries and bone loss are the most common diseases in oral cavity. The prevalence of these diseases will be reduced by controlling their risk factors. In this study, bitewing radiographs of patients were examined to illustrate the relationship between caries and bone loss.Materials and Methods: One-hundred and fifty bitewing radiographs of 86 patients were evaluated. In these radiographs, caries and distance between alveolar crest and CEJ were measured. In addition, confounding variables (contact type, tooth type, tooth surface) were assessed. Furthermore, patients were asked about the use of other possible risk factors of bone loss like smoking, brushing, and flossing. The data were analyzed using Regression analysis.Results: Findings of this study showed that the relationship between caries and bone loss was significant (P=0.02). Also, there were significant relationships between flossing (P=0.03), tooth type (P=0.0001) tooth surface (P=0.02) and bone loss. Finally the multivariate analyses considering confounding variables illustrate significant relationship between caries and bone loss (P=0.0001(Conclusion: Caries and bone loss have important roles as the risk factors for each other. Thus, it is necessary to prevent these risk factors and treat them as soon as possible to reduce these diseases.

Background and Aim: One of the most common problems after tooth extraction is alveolar bone resorbtion and in sufficient remaining bone for future implant insertion or appropriate denture fabrication to obtain adequate function and aesthetics. The aim of this study is to assess the effect of Ceno-bone (allograft) on reduction of alveolar bone resorption after tooth extraction.Materials and Methods: This research was rolled on 42 dental sockets in patients who were referred to oral and maxillofacial department of Shahed University during two years (2009-2011).The study design was split-mouth in which all sockets were divided in to case and control groups. Each socket was filled with Ceno-bone (FDBA) and sutured in case group and no material was added to the fresh sockets in control group. Follow-up radiographs were taken 1week, 2 months, and 6 months after surgical procedures. The results were statistically analyzed by paired T- test.Results: Alveolar bone loss in case and control groups were (0.86±0.36) and (1.33±0.48). respectively. Six months after surgery and there was significantly differences between two groups (p<0.002). There was not any significant differences between two groups one week and two months after surgical procedures. (P>0.05)Conclusion: Ceno-bone allograft (FDBA) seems to be an appropriate material for filling bony defects and accelerates bone regeneration and decreases resorption in remaining alveolar bone after tooth extraction.

Background & Aim: OPN gene has been shown to play an important role during bone resorption. The significant expression role of OPN gene in bone resorption hypothesizes the increased quantity of this glycoprotein during bone resorption induced by orthodontic tooth movement. The aim of this study was to assess the expression of OPN gene in rat bone resorption induced by orthodontic tooth movement.Materials & Methods: In an experimental study, fixed Ni-Ti closed coil springs were applied for mesial movement of the maxillary left first molars in 13 male 8-week-old Wistar rats. The animals' right maxillary first molars were used as internal controls of the study. The rats were sacrificed 21 days after application of orthodontic appliances. The scratched materials from mesial sides of the alveolar bone were used for PCR evaluation. The collected data were subjected to Wilcoxon Signed Rank Test.Results: Densitometry analysis of OPN coding mRNA on electrophoresis gel exhibited significant increase in gene expression on resorptive (mesial) side of the alveolar bone (P<0.001). The authenticity of PCR assessments was verified by GAPDH gene.Conclusion: Based on the results of this investigation and considering the study limitations, OPN gene expression increases during bone resorption induced by orthodontic tooth movements.

Background and Aim: The product of RANKL gene expression has a fundamental role in bone resorption and activates the chain of osteoclast differentiation from its predecessor cells. Reports of this gene participation and role in physiologic and pathologic bone resorption led to hypothesis that it may play a role in bone resorption induced by orthodontic tooth movement.Materials & Methods: A closed coil spring (Dentaurum Ispringen, Germany) was fixed by two pieces of ligature wires to mesial side of the maxillary right first molar and anteriorly to both incisors of fifteen 7 week old Wistar male rats to tip the first molars mesially. The maxillary left first molar of each animal used as an internal control group for the contralateral tooth. The animals were sacrificed on the 21st day of the experiment and the tissue from the mesial side of maxillary molars was used for PCR test. Wilcoxon Sign Rank test was used for densitometric analysis of RANKL mRNA on the electrophoresis gel.Results: Statistical analysis showed a significant increase in expression of gene in the experimental group compared to the control one (P less than 0.002). Genuineness of the PCR tests was verified by household gene of GAPDH.Conclusion: Based on the data obtained in controlled environment of the study, RANKL expression increased significantly following bone resorption induced by orthodontic tooth movement.