مجله تحقیق در علوم دندانپزشکی
سال یازدهم شماره 2 (پیاپی 40، تابستان 1393)

The current study compared the implant stability and radiographic crestal bone loss between HA/coated and RBM short Dentis implants in posterior maxilla. In this single-blind controlled clinical trial, 30 implants (15 RBM and 15 HA/coated Dentis implant) were placed bilaterally symmetrical or beside each other in posterior maxilla of 15 patients. All implants were placed in either the second premolars or the first and second molars area of maxilla. Implant stability and degree of crestal bone loss were recorded using Periotest and standard parallel radiography on the day of surgery, 1 and 3 months post surgery, and 3 months after loading the implant. Repeated measures ANOVA and T-test were used for data analysis. There was no statistically significant difference between the mean implant stability of the two implant surface at the baseline (-3.77±0.71), 1 (-3±0.77) and 3 months after surgery (-5.07±0.50), and 3 months after loading (-5±0.48) (P=0.67). The mean radiographic crestal bone loss revealed no statistically significant difference between the two implant types at baseline (P=0.42); however it was considerably lower in HA/coated implants at 1 and 3 months after surgery and 3 months after loading. (P<0.05) Since bone loss surrounding short dental implants is an important issue, it is recommended to use short implants with rougher surface (like HA/coated) in areas with poor bone quality.

The gag reflex is prevalent during dental impression taking. Conventional methods are available for controlling the gag reflex; however, they are not without side effects. Alternative treatments have been proposed for this purpose. The current study assessed the effects of acupuncture on patients who had nausea during the upper alginate impression taking. The study populations in this crossover clinical trial included (20) female dental students experiencing gagging during the upper alginate impression taking. Gagging Severity Index (GSI) and the Gagging Prevention Index (GPI)1-5 were used objectively by the operator and the Visual Analogue Scale (VAS) (0-10) was used subjectively by the patient to assess and record the Gagging Reflex (GR). The patients were allocated to groups of control, empirical 1 and empirical 2. Kruskal-Wallis test was used to analyze the changes of reflex ranking. A total of 60 samples (20 individuals) were assessed in this study. Their initial reflex during impression taking was observed to be 3.3±0.22, 1.35±0.53 in Sham group, indicating about 59% decrease (P<0.0001). In empirical group 2 it was equal to 1 showing 70% decrease (P<0.0001). Based upon VAS, GR had decrease by 49% in Sham group and 100% in case group (P<0.0001). According to results of this study it seems that acupuncture decreases the gag reflex during upper alginate impression taking.

Corrosion of orthodontic appliances is influenced by changes in the saliva composition resulting from physiologic stress. This study was conducted to assess the effect of stress on the level of nickel (Ni) and chromium (Cr) ions in the saliva of patients treated with fixed orthodontic appliances. Ten patients participated in this study. Saliva samples were collected at three different stages: T1: before placement of orthodontic appliances, T2: Three months after placement of fixed orthodontic appliances before stress, T3: 15 minutes after induction of stress (Trier Social Stress Test). Ion levels were measured by Atomic Absorption Spectophotometry. Data were analyzed by ANOVA and post hoc Bonferroni statistical tests. Ni levels increased from 12.78 ± 5.26 in T1 to 14.9 ± 5.75 in T3 and this increase was statistically significant. (P<0.05) Chromium (Cr) levels changed from 5.21 ± 3.38 to 6.27 ± 2.68, and the changes were not significant.(P<0.05) Stress significantly increases the release of Ni ions from orthodontic appliances into the saliva. Chromium levels of the saliva elevate gradually with time, however the change is not statistically significant.

Placebo analgesia has not been investigated extensively in dental settings. Using scaling and root planning (SRP) as a model, this investigation aimed at evaluating the placebo analgesia during SRP. Patients participated in this double-blind, randomized, controlled clinical trial. Having signed an informed consent form, and obtaining demographic characteristics, all the individuals filled a modified dental anxiety index questionnaire. Based on random blocks, 91 patients were given one placebo capsule 30 minutes before SRP as a potent pain killer, and 91 control subjects received SRP alone. Pain was recorded using a 10 centimeter VAS as well as a 5-point verbal Likert scale (VRS-5) during SRP for each sextant of dentition. Statistical analysis was done by chi-square, Spearman correlation coefficient, and Mann-U-Whitney tests using SPSS software version19. There was no statistical difference between placebo and control groups regarding anxiety, age, sex, pocket depth, and clinical attachment level (P>0.05). VAS and VRS-5 scores were not statistically different between case and control subjects using Mann-Whitney test. Spearman rank test revealed a correlation between the two pain measuring methods (P<0.0001). Within the limitations of this study, the placebo medication is not capable of reducing pain during SRP.

The current study evaluated the antimicrobial effects of MTAD, chlorhexidine and sodium hypochlorite on aerobic microorganisms in necrotic root canals. For this in vivo study, 17 necrotic single-rooted teeth with chronic apical periodontitis were used. After anesthesia and access cavity preparation, bacterial samples were taken from each canal using sterile paper points which were immediately transferred into BHI broth and were incubated at 37°C for 24 hours. For each sample, 4 aerobic plates were prepared and colonies were counted. Out of each series of plates, one without any antimicrobial agents was considered as positive control and the three others contained 100µl of MTAD, chlorhexidine0.2% and sodium hypochlorite 5.25%, respectively. After 3 days of incubation, the colonies remaining on the surface of the plates were counted and recorded as CFU/ml. Kruskal-Wallis test was performed to evaluate the difference between the antimicrobial activities of the irrigants. The mean percentage of bacterial growth inhibition in the presence of MTAD, chlorhexidine and sodium hypochlorite was 29.42%, 82.64% and 39.40%, respectively (P<0.0001). The antimicrobial effects of Chlorhexidine on aerobic microorganisms in necrotic canals seem to be higher than MTAD and sodium hypochlorite.

Lack of dental materials with adequate adhesion and sealing properties and the resultant microleakage is a major concern in dentistry. The use of denting bonding agents(DBA) in sealant therapy and their effect on microleakage remains controversial. This study was conducted with the aim to evaluate the level of microleakage in fissure sealants with and without DBA. In this experimental study, 45 sound premolars which were suitable for sealant application were chosen and assigned randomly into three groups. Sealant was applied to all teeth with the same conventional technique. In the first group, fissure sealant was applied without bonding agent, in the second group, it was used with total etch bonding agent (single/3M), and finally in the third group it was applied with self-etch bonding agent (G-bond/GC). Microleakage assessment was done by a stereomicroscope. Results were evaluated with Mann-U-Whitney and one way-ANOVA tests. This study was performed on 45 tooth samples. In the first group, %7 and in the third group, %7 had no leakage. In the second group, %60 of specimens had no leakage. The amounts of microleakage in control, experimental 1 and 2 were 42.6%,12% and 37.3% respectively, and their difference was significant (P < 0.001). Single-bond significantly increased the retention of sealant (P < 0.05). It seems that the best practice for the placement of sealants remains enamel preparation with acid etch and the use of an intermediate bonding layer. The results showed that using 5th-generation bonding agent in comparison with 7th-generation bonding agent and not using any bonding decreased microleakage

One of the major influential factors in the success of composite restorations is color stability over time. Discoloration of composite restorations can result in patient dissatisfaction and treatment failure in the long term. Lack of adequate information and contradictory reports regarding this issue lead to the current study which was performed to evaluate the effects of coffee on discoloration of three nanocomposites using spectrophotometry method. In this experimental study, 30 disc-shaped specimens (8.5×2mm) of three composite brands (Z350 XT (3M ESPE), Grandio (VOCO, Germany) and Herculite XRV Ultra (Kerr Co., USA) were prepared. All specimens were of A2 shade. Ten samples of each brand were divided into two subgroups, 5 to be stored in coffee and 5 in distilled water for 72 hours. Color measurements were obtained using a Spectrophotometer before and after immersion in solutions. The two-way ANOVA test was used to evaluate the results. All composite samples immersed in coffee showed significant discoloration compared to baseline values (P<0.05). Discoloration in samples immersed in distilled water was not significant compared to baseline (P>0.05). The difference in composite discoloration within the three sample groups immersed in coffee was significant (p=0.0001), however, no significant difference in discoloration was reported within sample groups immersed in distilled water (p=0.1). Based on the results of this study, some degree of discoloration was reported in all three composite brands immersed in coffee. The degree of discoloration was clinically unacceptable.

Tumor associated tissue eosinophilia (TATE) is observed in several types of neoplasms, however, its relation with cancers such as Squamous Cell Carcinoma (SCC) which is the most common malignancy of head and neck has not been identified; This study aims to evaluate the relationship between TATE and histologic grading of head and neck SCC (HNSCC) by Luna’s histochemical staining. In this descriptive study, 67 slides of 4μ HNSCC tissue sections were stained with hematoxylin and eosin. Samples were reviewed to evaluate histologic grading and then were divided into three groups as follows: Well-Differentiated, Moderately-Differentiated and Poorly-Differentiated. Eosinophil infiltration in tumor was assessed with Luna’s histochemical staining technique and eosinophils were counted and classified as follows: none (0), low (1-4), moderate (5-19), high (≥20). They were randomly evaluated per 10 microscopic fields. Kruskal-Wallis test and Spearman correlation coefficient were used to analyze the results. Tissue eosinophilia was found to be zero in only one case (1.5%) whereas in other 66 patients (98.5%) it was reported to be positive. The mean±SD number of counted eosinophil cells was 5.41±4.74. There was a significant correlation between the degree of histopathologic grade and TATE (P=0.04), but no significant relationship was detected between TATE and age, sex and lesion location. Tissue eosinophilia in Poorly-Differentiated group of HNSCC patients was lower than the other two groups, but no relationship associated with other clinicopathologic factors was found.

Early diagnosis of strip root perforation is a critical factor which has considerable impact on the treatment prognosis. The current study assessed the sensitivity, specificity and accuracy of cone-beam computed tomography (CBCT) compared to conventional periapical radiography (PA) in detecting the strip root perforations. The mesial root canals of 97 extracted human mandibular molar teeth were assessed in this diagnostic in-vitro study. The Distal wall of the mesiolingual canals were thinned in the danger zone. Then strip perforations were created randomly in 51 teeth. PA images (3 horizontal angles: 20̊ mesial, orthoradial and 20̊ distal) and CBCT were taken and they were evaluated by two observers. Accuracy, sensitivity and specificity of each method were calculated. Data were analyzed statistically by the Chi-square and Fisher’s exact tests (significance level=0.05). The sensitivity, specificity and accuracy of CBCT method in detecting strip perforations were 90.1, 100 and 94.8, respectively, and for the PA method they were 70.5, 69.5 and 70.1. The difference between PA and CBCT was statistically significant (P <. 05). It can be concluded that CBCT was superior to PA in detecting strip root perforations, and that conventional radiography was not efficient enough to detect strip root perforation.

The actual fluoride content of packaged milk and infant formulas are among the main concerns of the dental society. Regarding the lack of information about this issue, the current study aims to determine the concentration of fluoride in cow’s milk and formulae widely used in Tehran, Iran, 2012. In this cross-sectional study, samples of 9 common brands of cow’s milk and 2 milk-based powdered infant formulas were obtained and the fluoride content of the samples was assessed using potentiometry method. The ANOVA test was performed to analyze the statistical results of the study. The mean fluoride concentration in milk samples was 0.15 ± 0.06 ppm however, the difference was not statistically significant. (P<0.5) The minimum fluoride level was 0.12 ± 0.1 ppm in Damdaran brand of cow’s milk while the maximum fluoride concentration was found to be 0.17 ± 0.08 ppm in Choopan Brand. The difference in fluoride content was not statistically different. (p<0.5) It seems that there is not statistically difference between the amount of fluoride in drinking milk brands in Tehran. Clarification of the amount of fluoride content in this products is suggested.

Measurement of stress in children during dental procedures is one of the treatment concerns. The Modified Child Dental Anxiety Scale (MCDAS) is a questionnaire capable of appropriate assessment of dental anxiety in children. The present study aims to investigate the adequacy of the Persian translated version of the questionnaire for assessment of dental anxiety in Iranian children. In this descriptive study, 260 children aged 9-12 were selected by non-randomized sampling method; and they were subjected to the MCDAS, Corah’s Dental Anxiety Scale (CDAS), and Venham Picture test (VPT). The MCDAS was first translated into Persian, and then retranslated to English and it appeared to be reversible. After completing the questionnaires, internal consistency and correlation of these three questionnaires were measured using Cronbach’s alpha and Pearson test, respectively. The Cronbach’s alpha showed internal consistency of MCDAS, CDAS and VPT to be 0.8, 0.6 and 0.6, respectively. The consistency of MCDAS with CDAS and VPT was higher compared to CDAS and VPT (P<0.01). The MCDAS seems to functions better than VPT and CDAS. Further studies are also recommended in this regard.