Journal of Dental Medicine

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The cleaning and shaping of root canals is one of the most important proccesses in endodontics. In many cases, the physiologic or pathologic proccedures can affect the canals. So, using the instruments and materials, which could be applied in cleaning and shaping of narrow canals is necessary. The aim of this study was the evaluation of Iranian and foreign chelating agents on periradicular tissue of cats. After cleaning and shaping of canals in 18 lower canines of cats, the original RC-Prep and an Iranian chelating agents were placed equally in two groups with 9 teeth in each one. The patency of canals preserved for materials leakage. In 3 lower canines of cats, phosphoric acid was placed as positive controls.3 canine teeth as negative controls had nothing in them. The crowns were sealed and the cats were sacrificed in 1/21/42 days periods after conducting vital perfussions. The teeth samples with their surrounding osseous tissues were gathered and placed in three groups each contained 6 samples. Histologic preparations were done and the tissue reactions to these materials were evaluated by counting the proliferative inflammatory cells. Also the morphometric analysis for these samples was done. The inflammatory reactions of these materials (the original RC-Prep. & the Iranian chelating agent) were not statistically different. Both of these materials were different in inducing tissue reactions in comparison with those of positive and negative controls, and these differences were statistically important.

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Determination of puberty age of girls have been the research subject of researches and jurisprudents. The aim of this study was to investigate the relationship between tooth eruption and puberty in 12 year - old girl students. This cross-sectional study was conducted on 300, 12-year-old girl students in Mashhad, selected randomly. For each subject, a questionnaire was completed, including the information about the eruption rate of the teeth number 3,4,5,7 and the first menstruation, as puberty index to analyze the results, Mann Whitney test was used. The results of this study showed that, from among 300 female students, just 25% of them attained puberty at the age of 12.On the other hand, a direct relationship was observed between puberty and complete eruption of the second right maxillary molar and the first and second left mandibular premolars, which was statistically significant.

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Statement of Problem: One of the easiest and most practical methods to predict the size of permanent canines and premolars, is of Tanaka-Johnston, but their research has been only performed on white skin North Europeans and it should be noted that the size of teeth, in various races, differ from each other.
Purpose: The aim of this study was to determine the validity of Tanaka-Johnston method, in a sample population taken from Ghazvin city.
Materials and Methods: The numbers of 235 pairs of study casts, prepared before any kind of treatment, were selected. The size of lower permanent incisors and permanent canines and premolars of both arches were measured. To analyze the results, "regression analysis" and "t test" were used.
Results: Based on the findings obtained from this study, new prediction equations as Y=12.9+0.4(X) and Y=]0.6+0.5(X) were presented for maxilla and mandible, respectively. However, these equations did not differ from Tanaka-Johnston equations statistically.
Conclusion: Tanaka- Johnston equations can be acceptably applied for the sample population taken from Ghazvin city, if the predictions are not overestimated.

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Statement of Problem: Panoramic radiography seems necessary at examination, diagnosis and treatment plan phases of removable prostheses treatment since most of the patients who request removable prostheses treatment have retained root fragments, impacted teeth, cycts and tumors that might not otherwise be detected.
Purpose: The aim of the present study was to investigate the incidence rate of retained roots, impacted teeth and suspected pathologic conditions in panoramic radiographics of patients referred to removable prosthodontics departments of four dental schools and five public centers.
Materials and Methods: In this case series study, 1232 panoramic radiographs were analyzed to detect retained root fragments, impacted teeth and pathologic conditions.

Results: From among 850 panoramic radiographs of patients seeking complete denture, the incidence rates of impacted teeth, retained roots and pathologic lesions were 1.3%, 9.5% and 4.0% respectively.Also from 382 panoramic radiographs of removable partial denture patients the corresponding measures were 2.9%, 11% amd 0.1%.
Conclusion: Due to the significant and evident problems in residual ridge, as well as pathologic conditions of the remaining teeth structures and their supporting tissues as partial prosthesis base, the necessity for panoramic radiographics in edentolous and semi- edentulous patients is reemphasized.

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Statement of Problem: Tooth extraction is always considered as the final treatment option in dentistry.Considering the numerous advances in dentistry, nowadays the preservation of the permanent teeth until old age is common. However, in most economically poor countries or those without security service insurance,the high rate of extraction, particularly among restorable teeth, is regrettable.
Purpose: The aim of the present study was to determine the reasons for tooth extraction among patients referred to the faculty of Dentistry, Tehran University of Medical Sciences in 2002.
Materials and Methods: This descriptive and cross-sectional study was conducted on 320 patients. The information about patient's general knowledge, oral health status, tooth location and causes of extraction were collected and recorded in a questionnaire. The data were submitted to statistical Chi-Square test.
Results: No statistically significant difference was found between two genders in their mentioned causes for extraction. The most prevalent reasons were as follows: Caries (50%), Periodontal diseases (16.6%). Absence of an acceptable occlusion, prosthetic problems, patient's request, etc... make up the remaining 33.4% of the reasons.
Conclusion: According to this study, it is suggested to investigate extraction etiology at the society level and if similar results are obtained, necessary steps should be taken to prevent caries and periodontal problems as the major mentioned causes for tooth extraction.

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Statement of Problem: There are different tooth brushing methods for removing dental plaque from tooth surfaces. The effectiveness of these methods, and the time needed for instruction, learning and using seem to be different. Also, it is possible that the effectiveness of each method reduces with time, based on its difficulty level and the reduction of the patient s attention in following the given instructions. Purpose: The aim of this research was to compare the effectiveness of six different accepted tooth brushing methods on total and specific teeth, as well as on special tooth surfaces. The research also compared the time needed for instruction, learning and using the methods. Materials and Methods: The study was designed as a single blind randomised controlled trial protocol to compare the six accepted tooth brushing methods: Roll, Bass, Charters (C), Modified Stillman (MS), and Modified Bass in two ways (MB1-MB2). 15 volunteers were selected from the basic science level dental students at Tehran University of Medical Sciences. All the six methods were instructed to each volunteer, using a randomly selected sequence. Each participant should, therefore, pass six consequent courses, by the same sequences as follow: 1st Visit: After polishing the teeth, the participant was asked to abstain any kind of tooth cleaning. - 2nd visit (48-72 hours later): O Leary Plaque Index (PI) was recorded and then the randomised selected method was instructed. Then, the participant brushed his/her teeth and PI was registered again. The time needed for instruction and using the method was registered too. The participant was then asked to use this newly learned tooth brushing method twice a day for 7±1 days. - 3rd visit (7±1 days later): PI was recorded. The teeth were polished. The participant was asked to abstain any kind of tooth cleaning for 48-72 hours, as washout period of the previous method and preparation period for the next method (2nd visit of the next course). The final stage was comparing the results, in which the effectiveness of each method was evaluated based on the mean percentage of plaque reduction after the first usage, and also the mean percentage of the plaque remained after using the method for 7±1 days. The time needed for instruction, learning and using the methods were also compared. The statistical analysis was done using the SPSS software and variance analysis (randomised block design).

Results: Considering all the teeth and their total surfaces after 1st usage, the methods of C and MB1 were statistically more effective than the other methods. But the difference between these two methods was not significant. Also after 7±1 days, the differences between all methods were not statistically significant. On the posterior teeth, after 1st usage and also after 7±1 days, the method of C was significantly more effective than the others, with the exception of MB1 for which their differences were not significant. Also MB1 was significantly more effective than the methods of Bass and Roll, but only after the 1st usage. On the anterior teeth, after 1st usage, method of C was statistically more effective than the methods of Bass, MB2 and MS. Also MB1 was significantly more effective than MB2 and MS. But after 7±1 days, the differences proved insignificant. Considering the specific surfaces of the teeth on the proximal surfaces, after the 1st usage of the methods, the methods of C and MB1was significantly more effective than the others, except each other, which their difference was not significant. But after 7±1days the method of C was statistically more effective only than the methods of Bass, MB2 and MS, and the method of MB1was significantly more effective than MB2. On the buccal and lingual surfaces the differences were not statistically significant at both stage of evaluation. When statistically considering the time needed for instruction, learning and usage, the method of C needed more time than Bass and Roll methods. In the same way, MB1 needed more time than Roll method. The most time needed was related to MB2 which was more than the time needed for the methods of Bass, Roll and MS (P<0.001 and α=0.05).

Conclusion: The tooth brushing methods of Charters’ and a kind of Modified Bass method (in which Bass and Roll methods are used separately and consequently) were evaluated as the most effective methods.

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Statement of Problem: Tooth extraction is a common technique in orthodontics and most of the specialists believe that this technique is able to change the facial appearance.

Purpose: The aim of this study was to investigate facial vertical changes in orthodontic patients following tooth extraction.

Materials and Methods: Thirty patients, after their growth spurt, with CLI malocclusion all treated by a specific orthodontist through Edgewise technique along with the extraction of four first premolars were chosen. Lateral cephalograms of patients, before and after treatment were compared and facial vertical changes and teeth were studied.

Results: Anterior and posterior facial heights were increased during treatment. Despite the limited use of intermaxillary elastics, teeth were extruded. The most increase in facial heights was observed in the lower third of face. Patients with longer faces before treatment showed more extrusion of mandibular molars as well as more increase of mandibular slope.

Conclusion: Tooth extraction in orthodontic treatments can not guarantee the decrease or even non-increase of facial height. Among patients with long faces, it is particularly suggested to refrain from the application of extrusive orthodontic forces.

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Background and Aim: With the introduction of porcelain veneers to fulfill patients’ esthetic needs, question raises about the ability of the veneers to cover the substructure discoloration. It seems that using shade modifiers under the porcelain veneers can neutralize the discoloration. The goal of this study was to determine the efficacy of shade modifiers in correcting tooth discoloration, when used with resin cements under porcelain veneers.

Materials and Methods: In this experimental study, 60 porcelain discs with two thicknesses of 0.7 mm and 2 mm (30 porcelain of each thickness) were made from ceramco porcelain powder. 40 of them were in A2 shade and 20 were made by the mixture of A2 shade porcelain powder and porcelain stain to represent tooth discoloration. Then all the laminate discs (0.7 mm) were cemented over the 2 mm thick discs to make groups of 10 samples as followed: 1- The first group: laminate discs + resin cement + 2mm thick discs with A2 shade. 2- The second group: laminate discs + resin cement + 2mm thick discolored discs. 3- The third group: laminate discs+ resin cement+ shade modifier+ 2mm thick discolored discs. The color of 30 specimens was measured by spectrophotometer in 2 conditions. 1- To include the specular reflection (SCI). 2- To exclude specular reflection (SCE). In each condition the specimens were measured on both a white background (W) and a black one (B). The mean color differences (E) of each specimen in the second and third group with the specimens of the first group were calculated. Data were analyzed using Paired sample t-test and P<0.05 of significance.

Results: Color measurements showed that in SCIW condition L was significantly different among the three groups except the first and the third. In SCEW condition all the parameters showed significant differences. In SCIB condition, E was not significantly different between the second and the third groups. Hue (h) parameter wasn’t different between groups one and three neither was chroma (c) among the three groups. In SCEB condition, E was not statistically different between groups two and three.

Conclusion: Considering the statistical results, shade modifier couldn’t completely match the color of the specimens in the third group with the first one. But, the lower E for the third group comparing to the second one means that shade modifier was successful in reducing the effect of substructure discoloration.

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Background and Aim: In recent years, different substances have been considered in gingival cervical fluid (GCF) as diagnostic markers due to the evaluation of biologic events and biochemical process related to bone turnover during orthodontic movements. IL-6 concentration increases in GCF during the first week after force loading. The aim of this study was to investigate the levels of IL-6 in GCF during orthodontic movements.

Materials and Methods: Fourteen orthodontic patients (9 females and 5 males, mean age 15.1±2.5 years) with Cl I malocclusion needing first bicuspid extraction participated in this clinical trial. In each patient one maxillary canine was distalized (DC) with a NiTi push coil spring. The contra-lateral canine (CC) was included in the orthodontic appliance but was not subjected to the orthodontic force  and one of the mandibular canines was used as control with no orthodontic appliance (Antagonist canine: AC). The concentration of IL-6 was evaluated at the baseline and 14th and 28th days after intervention. GCF was taken with periopapers from both mesial and distal sides of tooth before appliance activation, on the 14th and 28th days. Concentration of IL-6 in DC, CC, and AC detected by ELISA reader was compared by repeated measure ANOVA and LSD multiple comparison, P<0.05 was considered statistically significant.

Results: Although the inflammatory gingival indices increased in both DC and CC teeth but it was not significant. The amount of IL-6 in GCF increased on day 14th in DC teeth in comparison with AC and CC teeth. In addition, the concentration of IL-6 in DC teeth was significantly greater than the 1st and 28th days. The maximum concentration of IL-6 was detected in both pressure and tension sides of DCs at T₁₄. At T₂₈, although the IL-6 levels were significantly higher than baseline levels but, it was significantly less than T₁₄.

Conclusion: The results of this study support the hypothesis that mechanical stimuli cause an inflammatory reaction within the periodontal tissues.

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Background and Aim: Multiple systemic and local factors contribute to the incidence and progression of periodontal diseases. Osteoporosis is defined as changes in trabecular bone structure and probably as a systemic risk factor of periodontitis. Since both diseases are considered as major public health problems and affect numbers of adults the aim of this study was to investigate the relationship between osteoporosis and periodontal disease and the role of oral hygiene in this process.

Materials and Methods: In this historical cohort study, 68 patients were selected from 111 individuals for whom femoral and hip BMD (Bone Mineral Density) with DXA (dual energy X-ray absorptiometry) procedure was performed and PI (Plaque Index) recorded. Cases were divided into four groups of 17 persons each as follow: osteoporotic with good oral hygiene (OH), osteoporotic with poor oral hygiene (OP) normal with good oral hygiene (NH), and normal with poor oral hygiene (NP). Clinical examinations including BOP (bleeding on probing),GR (gingival recession), PPD (probing pocket depth) and TL (tooth loss) was performed for all cases. Data were analyzed by two-way and four-way ANOVA test, with p<0.05 as the level of significance.

Results: Significant relation was observed between GR (P=0.045), and TL (P=0.050) with BMD independent of oral hygiene. Whereas such relation was not true for BOP and PPD (P=0.989).

Conclusion: Our finding showed that osteoporosis can make patients more vulnerable to periodontal diseases by reducing trabecular bone mass and is related to gingival recession as well as tooth loss.

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Background and Aim: Plaque control has always been important in preventive dentistry. Various methods and materials have been introduced for this purpose. Recently a three-colored tooth paste has been introduced which claims to prevent plaque formation. The aim of this study was to compare three-colored pouneh tooth paste containing triclosan with the conventional one in preventing plaque formation.

Materials and Methods: This was a randomized double blind cross over clinical trial which was carried out on 40 dental students of Tehran azad university in 2005. Before beginning the trial, the index of plaque was evaluated, registered and reduced to null. The subjects were randomly divided into two groups, the case group (three color tooth paste) and the control group (conventional tooth paste). The participants were asked to apply the specified tooth paste with an oral B Advantage Artica toothbrush for two weeks. After two weeks, the amount of plaque was re-registered and again reduced to null. The type of tooth paste was changed among two groups and the plaque was registered for the third time at the end of two weeks. Then the patients and assessors were not aware of the type of tooth paste in the tubes (double blind). McNamar and ManWhitney test were used.

Results: From the 40 subjects, 4 cases were omitted due to the different reasons. The amount of initial plaque index was 88.3 12.1 which was reduced to 78.2 16.9 in the control and 74.1 19.3 in the case group. The difference between primary plaque and secondary plaque (after applying tooth paste) was significant in both case and control groups, however there was not any significant difference between two groups.

Conclusion: Based on the results of this study, there was not any significant difference between conventional and three-colored tooth paste in reducing the plaque index.

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Background and Aim: Black staining after taking iron drops on the primary teeth is always concern of parents. There is not an exact explanation for the mechanism of iron black staining. The purpose of this study was to compare tooth discolorations, atomic absorption and structural changes of primary teeth enamel caused by two kinds of iron drops[ Kharazmi(Iran) and Fer-in-sol(USA)].

Materials and Methods: In this ex-vivo study, 93 sound primary teeth in normal color range were divided into five groups. Two groups of samples were immersed into the Artificial Caries Challenge(ACC) for two weeks before getting exposured to iron drops: Group 1 Control(NS): sound enamel teeth which were kept in Normal Saline environment(NS)(13teeth). Group 2 (NS-KH): NS, kharazmi iron drop (20 teeth). Group 3 (ACC-KH): ACC, Kharazmi iron drop (20teeth). Group 4 (NS-F-in-S): NS, Fer-in-Sol iron drop (20teeth). Group 5 (ACC-F-in-S): ACC, Fer-in-Sol iron drop. Visual tooth discolorations were determined by a specialist in operative dentistry who was not aware of experimental groups. The iron concentration was measured by ICP system (Vista-pro, Australia) and the structural changes were studied by SEM (Philips, Netherland). The data of discoloration were studied with Kruskal-Wallis test and multiple comparison using Bonferroni type test, and with the data of atomic absorption were studied with oneway ANOVA test and Tukey HSD test.

Results: The discoloration in the teeth immersed into the ACC (ACC-KH, ACC-F-in-S) was more severe than the sound enamel surface (NS-KH, NS-F-IN-S) (p<0.001) and Kharazmi iron drop caused more discoloration in the teeth immersed into the ACC (p=0.018). The teeth immersed into the ACC, absorbed more iron than the sound enamel surface (p<0.001) and also the teeth immersed into the ACC absorbed more Kharazmi iron drop (p<0.001). In the Scanning Electron Microscopy study, at low magnification in the sound teeth the perikymata was arranged regular. At low magnification in the teeth immersed into the ACC, many fractures were observed. The fractures in group 3(ACC-KH) were more and deeper.

Conclusion: Being immersed into the ACC, caused more iron absorption, severe discoloration and structural changes in the enamel of primary teeth. Such changes were more distinct in the teeth exposed to Kharazmi iron drop than the teeth exposed to Fer-in-Sol iron drop.

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Background and Aim: Extracted teeth used in preclinic should be disinfected. The aim of this study was to evaluate the effects of some disinfectants on microorganisms cultured from pulp chamber of extracted teeth.
Materials and Methods: In this experimental study 54 intact human teeth were collected. After access cavity preparation, 10 8 B. streothermophillus endospors were inoculated into pulp chamber. Then cavities were sealed with a temporary restorative material. Teeth were divided into 5 groups of 10 each. The teeth were then stored in these disinfectants: 5.25% hypochlorite sodium, 5% Microten, 5% Deconex, 2% Glutaraldehyd, and 10% Formalin for 48 hours. Two teeth were autoclaved as negative controls and two were stored in normal saline as positive controls. The teeth were then sectioned in cervical area and cultured in Trypticase Soy Broth. After three days turbidity in tubes was evaluated. Statistical analysis was done by Fisher's exact test.
Results: None of these solutions were able to prevent microorganism growth in all samples however, Formalin was better in six cases than that of other disinfectants. Differences between these five groups were not statistically significant (P=0.384).
Conclusion: Sterilization of the teeth with autoclave is the only absolute method for disinfecting the root canals of extracted teeth and disinfectants are not reliable for this purpose.

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Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movements and to inhibit the pain during tooth movements. Considering the contradictory finding in this respect, the effect of low level laser therapy (LLLT) was evaluated on the pain during orthodontic tooth movement.

Materials and Methods: In this randomized clinical trial study, 12 patients were included with extracted upper first premolars and required canine retraction into extraction site. While in both sides canines were retracted by Niti coil spring, one side was exposed to GaAlAs laser (890nm). LLLT was done on the buccal and palatal mucosa by slow movement of probe. The patients were asked about their pain on both sides 2 days after beginning of retraction. Pain measurement was evaluated with VAS.

Results: Pain perception in LLLT side significantly decreased (P=0.007).

Conclusion: Based on the results, single irradiation of GaAlAs laser (12J energy per tooth) can decrease pain perception.

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Background and Aims: Freestanding fixed partial prosthesis is considered the first choice whenever possible. However, anatomical limitations for implants and other reasons may create situation in which it would be preferable to connect the implants to teeth. A biomechanical dilemma in a tooth/implant-supported system comes from dissimilar mobility. This disparity cause the bridge to function as a cantilever and a series of potential problems such as osseointegration loss, screw loosening arise. The aim of this study was to analyze the tooth-implant supported bridges in rigid/non-rigid connectors in cemented prostheses using finite element stress analysis.

Materials and Methods: In this study four three-dimensional models were simulated by use of Solid works software. These models are: 1-RCCP: rigid connector between tooth and implant, 2-NRC CP1: non-rigid connector at mesial side of implant, 3-NRC CP2: non-rigid connector at distal side of second premolar, 4-NRC CP3: non-rigid connector at the middle of pontic, The stress values of four models loaded with vertical forces (150 N) were analyzed.

Results: The maximum stress concentration was located at the crestal bone around implant and stress distribution was more balanced around the teeth except in the model of NRCCP2. Stress distribution was imbalanced in non-rigid connection especially in the NRCCP1 model. The presence of non-rigid connector in bridge increases the stress values in suprastructure and transfers to the adjacent structures. Conclusion: The tooth-implant supported prosthesis should be considered as a valuable prosthetic option. It could be suggested that if tooth and implant abutments are to be used together as fixed prostheses supports, rigid connector is the choice because the prosthesis and implant possess the inherent flexibility to accommodate dissimilar mobility characteristics.

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Background and Aims: Multiple supernumerary teeth are rare and often found in association with syndromes such as Gardner, Cleidocranial dysplasia and cleft lip and palate, with a much less chance for isolated non-syndromic cases. The aim of this study was to report a case with 6 supernumerary teeth without syndromic association.
Case Report: The patient was a 33 year-old female, referred to oral diseases and diagnosis department with chief complaint of sensitivity to cold and hot food in right upper premolar region. Oral examination revealed 5 erupted lingually supernumerary teeth (four in mandibular and one in maxillary premolar region, respectively). Further panoramic radiography clarified an extra impacted tooth in the palatal region of left premolar maxillary area. All extra teeth had been appeared since the age of 17 during one year, as the patient claimed. Medical history and thorough clinical and paraclinical examinations were not significant except for the hypothyroidism, since 5 years ago. No other family member noticed to be the case. Based on our findings, a diagnosis of non-syndromic multiple supernumerary teeth was established.
Conclusion: A thorough examination of each patient presented with supernumerary teeth, including panoramic and intraoral radiographic images may provide valuable information regarding accompanying syndromes and unerupted teeth. Early diagnosis is an essential step for orthodontic or surgical decisions making, preventing or avoiding worsening complications such as malocclusion, adjacent normal teeth delayed eruption or rotation, diasthema, cystic lesions and resorption of contiguous teeth.

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Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movement. Considering the contradictory findings in this regard, this study was designed to assess the effect of low level laser therapy (LLLT) on the rate of orthodontic tooth movement.
Materials and Methods: In this randomized clinical trial study, 12 patients (4 boys and 8 girls average age:16.9 ± 3.4) with extracted upper first premolars and required canine retraction into extraction site were included. While in both sides canines were retracted by NiTi coil spring, one side was exposed to GaAlAs laser (890 nm). LLLT was done (on the buccal and palatal mucosa by slow movement of probe) at the beginning of the first month. Impression and cast fabrication performed at the beginning of retraction, one and two months later. The amount of retraction on the cast was measured with the aid of a reference plaque fabricated on the rogae using a digital caliper. Data were analyzed using paired sample T-test and one-sample Kolmogorov-Simirnov test.
Results: There was no significant difference in the amounts of canine movement between laser exposed and control sides (P>0.05).
Conclusion: The energy dose of laser used in this study (72 J per each tooth) was not appropriate for increasing dental movement.

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Background and Aims: The exfoliated human deciduous tooth contains multipotent stem cells [Stem Cell from Human Exfoliated Deciduous tooth (SHED)] that identified to be a population of highly proliferative and clonogenic. These cells are capable of differentiating into a variety of cell types including osteoblast/osteocyte, adiopcyte, chondrocyte and neural cell. The aim of this study was to evaluate the differentiation of SHED to osteoblast in standard osteogenic medium and comparing the results with medium which supplemented with glucosamine in form of chitosan.

Materials and Methods: Dental pulp cells were isolated from freshly extracted primary teeth, digested with 4 mg/ml collogenase/dispase, and grown in Dulbecco's modified Eagle's medium with 10 percent fetal bovine serum. The clonogenic potential of cells was performed after 3 weeks of culture. Flowcytometric analysis, performed at day 21 of culture to identify surface markers of mesenchymal stem cells. The cells from 3rd passage were used for osteogenic differentiation in routine osteoinductive medium. Chitosan (10 μg/ml) was added to the culture medium of case group. Alizarin Red Staining and Alkaline Phosphatase (ALP) activity were done to evaluate osteogenic differentiation in the developing adherent layer on the third passage. The results were analyzed using T-test. For the analysis of normal distribution of data, non-parametric Kolmogrov-Smirnov test was used.

Results: The colonogenic efficiency was more than 80%. Flowcytometric analysis showed that the expression of mesenchymal stem cell marker CD90, CD105 and CD146 were positive in SHED, while hematopoietic cell marker CD34, CD45 and endothelial cell marker CD31 were negative. Quantitative analysis of Alizarin Red Staining demonstrated that: mineralized nodule formation was higher in the group supplemented with glucosamine (chitosan). Results from Alkaline Phosphatase activity test, on day 21, demonstrated a significantly higher ALP activity in the group supplemented chitosan (P<0.001).

Conclusion: Stem cells isolated and cultured from exfoliated deciduous teeth pulp can be differentiated to osteoblast. Addition of chitosan can be beneficial to promote osteogenic differentiation of these cells.

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  Background and Aims: Iatrogenic damage to adjacent tooth during proximal cavity preparation is one of the most common side effects in operative dentistry. The aim of this study was to determine prevalence of iatrogenic damages to adjacent tooth during the preparation of proximal Class II cavities among undergraduate students at dental faculty of Tehran University of Medical Sciences in 2010 .

  Materials and Methods: 106 posterior permanent teeth which had Class II decay with sound proximal surfaces of adjacent teeth were selected and restored by dental students awarding the aims of the present study. After finishing restoration, proximal surfaces were completely dried by air and evaluated with dental chair light. In doubtful cases, surfaces were evaluated with × 3 magnification. Damages were classified into 2 groups abrasion and groove. Data were analyzed using Fishers exact and Pearson chi square tests .

  Results: The frequency of adjacent surfaces damage were 57.5%, with 31.1% damages as abrasion and 26.4% as groove. Students who used matrix band and wedge in proximal area as preventive instruments showed 53.4% damages and other students showed 57.3% damages (P>0.05). A significantly higher number of females and students at restorative course level (3) used wedge and matrix band than males and students at restorative course level (4) for protecting adjacent teeth (P<0.05).

  Conclusion: According to the high percentage of iatrogenic damages on adjacent sound teeth in class II cavity preparation, teaching of preventive methods and using proper techniques is necessary for dental students as future dentists.

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  Background and Aims: Impacted third molar reduces the bone level in the distal aspect of second molar, and sometimes it can lead to root resorption of the adjacent tooth. The purpose of this study was to determine this resorption using panoramic and periapical radiographs.

  Materials and Methods: In this cross-sectional descriptive study 54 patient (28 men, 26 women) above 15 years old with the average of 22 years in Oral and Maxillofacial Department of Tehran University were studied. A periapical radiography from the third molar and a panoramic radiograph were taken from each patient (Because of their routine use and evaluation of accuracy of panoramic compared with periapical), and the magnitude of the root resorption for the second molar was determined by 2 observers and written in a questionnaire. Data were analyzed using Fisher test.

  Results: The prevalence of the root resorption of the second molar adjacent to the impacted third molar in the panoramic and the periapical radiographies, with respect to the limitation of the sample size were 46.3% and 31.5%, respectively, with 95% confidence(P>0.05). Most of these resorptions were in the cervical third of the second molar roots and in cases in which the third molars were mesially oriented or horizontal. There was also no significant difference between panoramic and periapical radiographs.

  Conclusion: Due to the increased risk of the resorption of the second molar adjacent to the third molar, extraction of the impacted third molars, especiall y mesially oriented or horizontal ones are recommended.