JOURNAL OF ISFAHAN DENTAL SCHOOL
Year:2011 | Volume:7 | Issue:2|Papers Count:14

Introduction: Irrigation solutions used in root canal therapy might alter the wettability of root canal dentin, thereby affecting adhesion of dental materials. The aim of this study was to compare the effects of three different endodontic irrigants on the free surface energy of radicular dentin.Materials and Methods: In this in vitro study, 48 extracted human maxillary incisors and canines were used. The middle portion of each root was sectioned longitudinally to prepare an appropriate dentin sample. After polishing and embedding each sample in acrylic blocks, the samples were randomly assigned to 4 groups, and immersed in the following solutions for 10 minutes: group 1: saline solution (control), group 2: 2% (or 0.2%) chlorhexidine, group 3: 0.25% iodine, group 4: 1% sodium hypochlorite. The samples were then air-dried and the free surface energy of dentin was measured in dyne/cm. Data were analyzed using one-way ANOVA and Tukey test (a=0.05).Results: The means and standard deviations of free surface energy in groups 1 to 4 were 60.87±2.46, 57.54±2.86, 59.83±5.38 and 51.67±2.22, respectively. One-way ANOVA showed significant differences between the groups (p value<0.001). The results of Tukey test showed that the free surface energy of dentin was significantly lower than other groups after using 1% sodium hypochlorite (p value<0.001).Conclusion: The results of this study showed that endodontic irrigation solutions, mainly 1% sodium hypochlorite, reduce free surface energy of dentin, adversely affecting adhesion of dental materials to dentin.

Introduction: Analysis of gingival crevicular fluid (GCF) may be a good means of examining the biochemical processes associated with bone turnover. The aim of this study was to evaluate the specific activity of acid phosphatase (ACP) in GCF during canine retraction with sliding technique.Materials and Methods: In this clinical trial 5 subjects (aged 12-20 years) with bimaxillary dentoalveolar protrusion were selected. After extraction of four first premolars, the sliding technique was used to retract canines in each subject. GCF samples were collected from the distal aspect of each canine by using sterile paper points (#15) at four time intervals: immediately after the appliances were fitted, at the time of initial activation, and 15 and 30 days afterwards. Acid phosphatase and microprotein levels were assayed by means of quantitative colorimetric technique.Tooth movement at each sampling interval was measured. Data was analyzed with non-parametric tests of Freeman, Mann-Whitney, and Pearson’s correlation coefficient (a=0.05).Results: After activation of the appliances, average specific activity of acid phosphatase in GCF significantly increased (p value<0.001). In addition, the specific activity of ACP at sampling intervals showed significant differences (p value<0.001). No significant relation was noted between changes in specific activity of ACP and tooth movement (p value=0.215).Conclusion: It is possible to measure specific activity of acid phosphatase in the GCF during orthodontic tooth movements. It is elevated in the pressure side during orthodontic tooth movement.

Introduction: Applying the suitable mouthwash can kill bacteria or reduce the bacterial growth, in the same context, diluting mouthwashes can decrease their probable side effects. In this study, the maximum inhibitory concentrations of two common mouthwashes were evaluated.Materials and Methods: In this in vitro study, agar dilution and disk diffusion methods were used.Sixty-nine bacterial plates were cultured to evaluate the effects of thymol and chlorhexidine mouthwashes on Streptococcus mutans and Streptococcus sanguis. The results of agar dilution method were recorded as “growth” and “no growth”, and the results of disk diffusion were recorded as means of growth inhibitory halos. Data was analyzed by Kruskal-Wallis test using SPSS software.(a=0.05).Results: Growth inhibitory halos for different concentrations of the two mouthwashes decreased with an increase in dilution rate. In agar dilution method, dilutions less than 80% of the initial concentration for thymol-based mouthwash and less than 70% for chlorhexidine could not inhibit bacterial growth. Growth inhibition halos with 100% thymol-based mouthwash (Orion Ò) were 10.15±0.1 mm for Steptococcus mutans and 9.27±0.16 mm for Streptococcus sanguis. Mean rank of the two mouthwashes was statistically significant for the two bacterial strains under study (p value<0.001).Conclusion: Both mouthwashes were effective on the bacteria under study, however, this efficacy was higher for Streptococcus sanguis. Chlorhexidine mouthwash was more potent to inhibit bacterial growth than thymol-based mouthwash if diluted.

Introduction: The proliferative capacity of dental pulp cells after replantation in the alveolus facilitates pulp regeneration and subsequent root maturation. The aim of this study was to compare milk, egg white and HBSS (Hanks Balanced Salt Solution) to maintain pulp cells' proliferative capacity in open apex teeth in rabbits.Materials and Methods: Sixty open apex incisors of rabbits were randomly stored for one, three and six hours in tubes containing milk, egg white and HBSS at 4oC, immediately after open surgical extraction. Following fixation and decalcification of the teeth, three histologic sections were prepared from the coronal, middle and apical thirds of the pulp and the presence of Ki-67 antigens was evaluated in the sections by immunohistochemical methods. The mean values of liability index were analyzed using repeated measures ANOVA (a=0.05).Results: Liability index of dental pulp cells stored in milk at one-hour, three-hour, and six-hour intervals were 13.7±4.37, 14.56±4.11, and 15.52±6.56, these indexes in egg white were 14.90±2.87, 17.66±5.9, and 12.23±3.87 and for HBSS they were 14.60±1.57, 14.14±5.02 and 18.85±6.54, respectively, during the same intervals.Conclusion: Pulp cells stored in milk, egg white and HBSS exhibited the same proliferative capacity at one-hour, three-hour, and six-hour intervals, with higher proliferative capacity in the apical third compared to the middle and in the middle third compared to the coronal third.

Introduction: Sucking habits have long been recognized to affect occlusion and dental arch characreristics. The aim of this study was to determine the association between nutritive (breastfeeding and bottle feeding) and non-nutritive (thumb or pacifier sucking) habits and posterior crossbite in the primary dentition.Materials and Methods: This descriptive cross-sectional study was carried out on 200 preschool children aged 3-5 years. The crossbite group (n=100) consisted of children with posterior crossbite and the normal group (n=100) was made up of children without posterior crossbite. Information on breastfeeding, bottle feeding, and non-nutritive sucking habits was collected using a structured questionnaire. Data was analyzed using chi-squared test and student’s t-test. Statistical significance was set at p<0.05.Results: Risk factors for posterior crossbite in preschool children were bottle feeding (OR=2.1), thumb sucking (OR=3.6), and pacifier sucking (OR=2.0). No association was noted between breastfeeding for more than 1 year and posterior crossbite (p value=1).Conclusion: Under the limitations of the present study, it appears posterior crossbite in the primary dentition in preschool children is directly related to bottle feeding, thumb sucking and pacifier sucking habits.

Introduction: The role of occlusal forces on dentition affected by periodontal diseases is not well known. Evidence suggests that high occlusal forces alter the extent of destruction and the nature of lesions. The effect of occlusal relationship on the periodontium has not been elucidated despite large number of studies, which have yielded contradictory results. The aim of this study was to evaluate the effect of different occlusal relationships on periodontal parameters.Materials and Methods: In this cross-sectional study, 60 healthy individuals were selected with anterior rise, cuspid rise, and group function occlusal relationships (n=20). They had no premature contacts on the balancing side. Periodontal parameters of pocket depth, attachment level, keratinized gingiva, gingival recession and plaque index were recorded. Data were analyzed with ANOVA and Kruskal-Wallis test (a=0.05).Results: Tukey test showed significant differences only in keratinized gingiva between anterior rise and cuspid rise occlusal relationships, in addition, Tukey test revealed significant differences in the upper jaw keratinized gingiva between anterior rise and cuspid rise occlusal relationships (p value<0.05).Conclusion: The results of this study did not determine which occlusal relationship is superior to others, although an increase in the keratinized gingiva was noted in cuspid rise occlusal relationship.In other words, all the three relationships had similar effects on periodontal parameters of pocket depth, attachment level, and gingival recession.

Introduction: Effective plaque removal is an important factor in the long-term clinical success of dental implants. The aim of this study was to compare the clinical efficacy of a powered toothbrush (Power Cross-Action) and a manual toothbrush (Cross-Action) in the control of plaque and soft tissue inflammation around implants supporting mandibular overdentures.Materials and Methods: This study was a cross-over clinical trial. The subjects included 10 edentulous subjects, aged 47-73 years, with removable mandibular overdentures supported by 2 unsplinted implants, all the subjects wore maxillary complete dentures. The study consisted of two 4-week phases separated by a 2-week interval. In each phase each subject randomly used one toothbrush type. Two days prior to each phase, the implants were polished. Plaque and bleeding indices were recorded before and after brushing. Data was analyzed by t-test using SPSS software (a=0.05).Results: Both toothbrushes reduced the indices under study. Means of plaque index decreases were 0.5 in manual toothbrush and 0.44 in powered toothbrush. Means of bleeding index decreases were 0.27 in manual toothbrush and 0.3 in powered toothbrush. There were no statistically significant differences between the two toothbrush types in changing plaque index (p value=0.88) and bleeding index (p value=0.91).Conclusion: Both toothbrushes were efficient in plaque control around implants which supported mandibular overdentures and there was no difference between them. Patients can use one of these toothbrushes depending on personal preference and comfort.

Introduction: Methods of root canal obturation, materials used and elimination of the smear layer have important roles in sealing the root canal system. This study compared the sealing ability of a resin-based sealer (Real-Seal) used with three different root canal irrigation protocols to remove the smear layer.Materials and Methods: In this experimental study, 85 single-rooted extracted human teeth were selected. After root canal preparation, the teeth were randomly divided into 5 groups: three experimental groups of 25 and two positive and negative control groups of 5 teeth. The final irrigants in groups 1, 2 and 3 were 17% EDTA+NaOCl, 7% citric acid+NaOCl and 20% citric acid+ NaOCl, respectively. All the groups were obturated with Real-Seal system except for the 5 positive control teeth. All the teeth were kept in an incubator for 48 hours. Root surfaces were covered with nail varnish except for the apical 2 mm. After 48 hours in the incubator, the roots were assembled in the system designed for this experiment, sterilized with ethylene oxide gas and transferred to BHI (Brain Heart Infusion) in an aseptic condition. A fresh solution of Enterococcus faecalis was injected into the system every 3 days. The samples were evaluated daily for 90 days and the time of turbidity was registered in each case. Kaplan-Meier test was used for data analysis (a=0.05).Results: There were no significant differences between the experimental groups (p value>0.05). The longest and shortest microleakage mean times were observed in the 20% citric acid and 17% EDTA groups, respectively.Conclusion: Real-Seal system with its resin-based sealer in association with 20% citric acid irrigation is recommended for root canal treatment.

Introduction: Aggressive periodontitis is associated with widespread systemic inflammation. Creactive protein is known as a mediator capable of establishing a connection between periodontal disease and several systemic diseases. Some studies have shown that C-reactive protein is superior to cholesterol in predicting cardiovascular problems and death as a result of cerebrovascular accidents. Previous studies have demonstrated the relationship between periodontitis and high serum levels of C-reactive protein in various societies. The present study compared the effect of periodontal surgeries and conventional non-surgical treatment modalities on C-reactive protein level variations in patients with moderate-to-advanced generalized periodontitis.Materials and Methods: In this clinical trial, 80 systemically healthy individuals with an age range of 28-37 years, who had moderate-to-advanced generalized periodontitis, were selected and divided into two equal groups of 40. One group was treated by conventional periodontal modality (scaling) and the other was treated by surgery. The subjects’ medical and periodontal parameters, including Creactive protein serum levels, pocket depth, bone loss and clinical attachment loss, were measured before and six months after treatment. Data was analyzed by SPSS 15 software using independent and paired t-tests (a=0.05).Results: The results showed that both treatment modalities decreased C-reactive protein serum levels, with the surgical treatment having a greater role in the decrease without any significant differences. Both treatment modalities significantly decreased pocket depths, but there was no significant reduction in the attachment loss and bone loss.Conclusion: It appears surgical periodontal treatment results in a greater decrease in C-reactive protein levels compared to non-surgical techniques but further studies are necessary.

Introduction: Reducing stress on implats in overdentures supported by two implants via optimal stress distribution is nessecery. The aim of this study was to evaluate stress distribution pattern around implants in overdentures supported by two impalnts with varying cantilever lengths using finite element analysis.Materials and Methods: The model used in this experimental-analytical study was an implantsupported overdenture with bar and clip attachment system on an edentulous mandibular arch. Two vertical impalnts with cantilever lengths of 0 mm, 7 mm, and 13 mm were connected by a bar.Vertical loads of 15 and 30 pounds were applied unilaterally to the first molar and 15 pounds to the first premolar, the stress in bone was analyzed by finite element method.Results: In the 7-mm and 13-mm cantilever models loaded by 15 Ib on the molar area, the stress values around the ipsilateral implants were 2.78 and 2.75 MP, respectively, compared to 3.06 MP in the model without cantilever. By loading a 30-Ib force in the molar area, stress values around the ipsilateral implants were 6.9, 6.42 and 6.28 MP in no cantilever, 7-mm and 13-mm cantilever models, respectively. No uniform pattern of stress distribution was seen by increasing the cantilever length, however, increasing cantilever length did not increase stress around the ipsilaleral implant.Conclusion: Within the limitations of this study, increasing cantilever length did not increase stress values, especially around the ipsilateral implants and it may be helpful to use cantilevers in cases of mandibular overdentures supported by splinted implants with insufficient retention and stability. Based on the findings of this study, optimal cantilever length in mandibular overdentures cannot be determined.

Probiotics are viable microorganisms which improve human health by inhibiting or reducing the number of pathogenic microorganisms. The most common probiotic strains are Lactobacilli and Bifidobacterium. Varying results have been reported about the effect of different probiotic bacterial strains on oral health and decrease in the counts of salivary Streptococcus mutans strains in previous studies. To have a favorable effect on oral health, a probiotic must have the capacity to adhere to tooth surfaces and must be integrated in the bacterial biofilm, it should also be able to compete with cariogenic bacteria and prevent their proliferation. Permanent and daily consumption of probiotics has been recommended for optimal results. Studies have suggested that probiotics can improve the oral cavity microbial equilibrium and the probable benefits increase with an early childhood use, however, caution should be exercised in the administration of probiotics in children because their oral microflora is not been established yet. Although bacteriotherapy with probiotics seems to have inhibitory effects on pathogenic oral microorganisms, further studies are necessary before any recommendations on their clinical use. The aim of this study was to review probiotics, mechanisms of their function, therapeutic effects, application techniques, their cariostatic effects and a review of randomized controlled clinical trials in this regard.

Introduction: Before placing or cementing a restoration into a cavity preparation, the clinician must decide whether a cavity base, liner or a protective cavity sealer should be placed. While this seems simple, the decision is complicated by an ever-increasing number of products available. In addition, the clinical success of an indirect restorative procedure depends, to a great extent, on the relationship between the restoration and the tooth. The practice of fixed prosthodontics has changed dramatically with the introduction of innovative techniques and materials. Adhesive resin systems are examples of these changes that have led to popularity of bonded ceramics and resin-retained fixed partial dentures.Materials and Methods: This review was collected with a scientific search in MEDLINE in relation to the following categories: the definition of liners, bases and cements, their clinical applications, mechanical properties, biocompatibility, principles of adhesion, specific types of materials and their use as liners, bases or cements. In addition, the review discusses cementation techniques for different types of restorations, and other relevant clinical information. Tables of products available and their properties are also presented.Conclusion: Although each cement type has been widely investigated, the correct clinical choice between them is not always clear. None of them is suitable to be used for the entire broad range of indirect restorative procedures. Therefore, their proper application requires a thorough nderstanding and awareness of each material's advantages and disadvantages, taking into account the restorative material, moisture control and preparation design (retentive or adhesive).A review of liners, bases and cements.