Journal of Mashhad Dental School
Year:2007 | Volume:31 | Issue:3|Papers Count:18

Introduction: The term bioadhesion refers to the attachment of a natural or systhetic polymer to a biological substrate: when this substrate is mucus, mucodhesion is the term used. The aim of this study was formulation and clinical evaluation of the first mucoadhesive film in Iran.Materials & Methods: In this clinical trial four mucoadhesive films (A, B, C, D) were formulated based on theoretical knowledge of adhesive polymers and physical properties of a mucoadhesive layer. For this, Hydroxy Propyle Metyle Cellulose (HPMC) polyvinyl povolidion (PVP) and carbapol (C), were used as adhesive layer and nitrocellulose (NC) and Ethylcellulose (EC) were used as hydrophobe layer. Films were assessed in a double-blind clinical trial study among 20 healthy volunteers on attached gingiva of maxillary canine. Maximum duration of attachment of films and effects of related factors were evaluated. Data were analysed using SPSS and by chi-square, t-test and repeated measurments.Results: There was a significant difference among four films according to mean duration of adhesion (P<0.001) so as film A showed maximum adhesion time (13 hours) and film D showed minimum adhesion time (5.15 hours). Mucosal compatibility of the adhesive films was good and eating and drinking had no effects on seperation of films from gingiva.Conclusion: It seems that film A is appropriate for mucosal adhesion. Further studies with different dimensions on this film are needed prior to its use as a mucoadhesive film in oral mucosa.

Introduction: Post endodontic treatment pain and swelling or both is named as Flare-up which is one of the problems after root canal therapy. This problem is particulary important in necrotic teeth because of infiltration of bacterial agents into the periapical region. Adequate and appropriate irrigation of canal removes intracanal microganisms, debris and infected agents from canal space and decreases the incidence of pain and swelling. Sodium hypochlorite is one of the most effective antibacterial irrigants which dissolves vital and non vital tissues. Chlorhexidine is another irrigant that has antibacterial characteristics. The aim of this study was comparison between the incidence of Flare-up after using chlorhexidine and sodium hypochlorite as irrigatns in root canal therapy of necrotic pulp.Materials & Methods: In this clinical trial study, 50 patients with single canal necrotic pulp without any symptoms were selected and were divided into two groups of 25. In any group, after isolation and access preparation, canals were prepared using rotary Race files. Canals were then irrigated with chlorhexidine 0.2% and sodium hypochlorite 2.5% and were finally obturated by lateral condensation. A questionnaire was given to the patients to fill the amount of their experienced pain using a visual analogue scale and swelling with a scale with 4 degrees. Patients were followed for 48 hours. The data were analyzed by Mann Whitney, Wilcoxon and Kruskal-Wallis tests.Results: There was no significant difference between irrigant solutions in decreasing the amount of pain and swelling after endodontic treatment. No significant relationship was detected between amount of pain and swelling, and age and sex. Flare-up was observed more in maxilla compared to mandible.Conclusion: According to less toxicity effect of chlorhexidine, sodium hypochlorite can be replaced by chlorhexidine.

Introduction: Since remaining impacted teeth may result in pathologic lesions, prophylactic extraction of third molarwhich is the most frequent impaction-is among the most common surgical procedures. Our study was performed to evaluate the histopathological changes of impacted molar teeth follicles.Materials & Methods: In this descriptive study, 54 impacted molar teeth follicles of 50 patients with age range of 15-38, and examined in the surgery ward of Mashhad dental school from June to November 2005, were extracted by a surgeon and pathologic evaluation were performed.Results: In this study, the most commonly extracted teeth were mandibular molars (79%) and 74% of patients were under 25. The most frequent location of the extracted teeth was mesioangular (46%). In microscopic evaluation of specimens, 61% were unchanged dental follicles, 12.9% were odontogenic cysts and 24% had inflammation.Conclusion: Considering the low incidence of pathologic changes in impacted third molar follicles, it is better not to extract them except in a clear indication. These teeth are better to be monitored by imaging with the 6-12 month intervals.

Introduction: Today most of endodontic treatments are successful and just a low percentage of them may lead to failure. This failure may be due to remaining necrotic and infected agents in root canal system which is because of the complex anatomy of root canal and the rooms not available during mechanical and chemical cleaning. So use of chemical solutions for bacterial disinfection and necrotic agent removal is recommended. The aim of this study was to compare NaClO chlorhexidine and normal saline solutions in eradication of S.faecalis as a resistant bacterium in routine endodontic treatments.Materials & Methods: In this experimental & In vitro study 50 single canal human extracted teeth were selected we made conventional access cavities on all of them. Then, the teeth were divided into five equal groups randomly. Next, they were sterilized in autoclave. After that, we injected S.faecalis in root canals and put them in 37°C incubator for 36 hours. After bacterial growth a culture was prepared from each tooth to determine bacterial growth rate. Finally endodontic treatment was done on the teeth. Duration, method of filling and type of files were the same in groups but the type of chemical solution was different. (group 1: Saline, group 2: Chlorhexidine, group 3: NaClO 2.5%, group 4: NaClO 1%, group 5: NaClO 5.25%). Another culture was prepared after treatment. At last the number of colony forming units before and after treatment was compared with each other. The data were analyzed by one-way ANOVA.Results: The results showed that there was a significant difference among NaClO (2.5%, 5.25) and other solutions in decreasing the number of bacteria in root canals after instrumentation. Normal saline, NaClO 1% and chlorhexidine solutions developed similar antimicrobial activites.Conclusion: Considering the results of this study,when we have limitations using Naclo, we Can use Normal Saline as a safe material. In necrotic teeth, use of NaClO 2.5% for better removal of organisms is recommended.

Introduction: Diabetes mellitus is one of the most common disorders of endocrine glands, which causes various complications including the increase of susceptibility to many infections such as oral candidiasis. The purpose of the present study was to investigate the association between median rhomboid glossitis (MRG) and diabetes mellitus.Materials & Methods: In this descriptive study 200 patients were selected randomly from Khorasan diabetes mellitus research center. The data were collected through a questionnaire and oral examination. The data were analyzed using Mann Whitney test, Exact-Fisher test.Results: In the present study, 19% of the diabetic patients male and 81% were female. The examination indicated that 7% of the diabetic patients had MRG. None of the males had MRG and 8.6% of the females had MRG. The highest frequency of MRG-infection was observed in patients over 40 years old, particularly in the age group of 70-79 years old prevalence of MRG was 14.3%.Conclusion: In this study the prevalence of MRG in diabetic patients was 7%.

Introduction: The appearance of superficial and deep dentin differs and this may affect the bond strength of adhesive system. The aim of this study was to evaluate the shear bond strength of superficial and deep dentin using self-etch system.Materials & Methods: This in vitro and experimental study was done on 48 human extracted premolar teeth. After mechanical cleaning, they were disinfected with hypochlorite 5.25 % and the roots mounted in acrylic resin. Teeth were divided into 4 groups: A, B, C, D. In A and B groups, buccal surface was reduced until dentino-enamel junction (DEJ). In C and D groups, buccal surface was reduced 3 mm deeper than DEJ. We used 2 groups of self-etch systems: Prompt-Lpop and Prime & Bond NT. Prompt-Lpop were used in A and C groups and Prime & Bond NT was used in B and D, according to their manufacturers’ instructions. Pieces of composite with 1.5 mm diameter and 2 mm height were bonded on treated buccal surface of teeth. Finally specimens were loaded to failure in a universal testing machine at a crosshead speed of 1mm/min. The two-way analysis of variance was used for comparing the shear bond strength among the various groups.Result: The mean value of shear bond strength of Prompt-Lpop in superficial dentin was 26.42±3.40 MPa and in deep dentin was 11.83±2.62, and of Prime & Bond NT in superficial dentin was 24.33±4.70 MPa and in deep dentin was 12.91±2.21. The mean value of shear bond strength of superficial dentin was 25.37±4.10 MPa and deep dentin was 12.35±2.42 Mpa. Statistical analysis of the data showed that there was not a significant difference in shear bond strength between Prompt-Lpop and Prime & Bond NT (P=0.613). There was a statistically significant difference in shear bond strength between superficial and deep dentins in each self etch system separately.Conclusion: According to data analysis conservative cavity preparation with less depth is recommended for efficient restoration when using self etchant dentin adhesive systems.

Introduction: Some reports show that oral manifestations such as uremia osteomatiis, self bleeding, periodontal diseases, xerostomia and calculus formation are increased in patients with renal disease. Based on similar structural composition and similar process of production of kidney stones and dental calculus, we performed this study to evaluate the prevalence of dental calculus in patients with kidney diseases.Materials & Methods: In this case-control study, 30 patients with idiopathic nephrolithiasis were selected as case group and 30 sex and age matched healthy persons were selected as control. They had no systemic and periodontal diseases. Silness-Loe plaque index and Green-Vermillion calculus index were recorded for both groups. Data were analyzed by Chi-square, Fisher’s Exact test, T-student and Two-way ANOVA.Results: Results of this study showed that there were not any significant differences between case and control groups in amount of plaque and dental calculus P=0.79.Conclusion: Patients with nephrolithiasis are not more susceptible to calculus formation.

Introduction: Today there are two common and different systems available for orthodontic treatments: Begg and Edgewise techniques. Occlusal indices have the greatest reliability for comparing treatment outcomes, so in this study we used Peer Assessment Rating index for comparison of treatment outcomes of these two systems. Peer Assessment Rating index evaluates buccal occlusion (Antero-posterior, vertical and transverse), overjet, overbite and midline by scoring them. The purpose of this study which has been conducted for the first time, was to compare occlusal PAR index in class I patients treated by means of Begg and Edgewise methods.Materials & Methods: In this cross sectional study, 120 pre-treatment models of 60 class I patients were evaluated by Peer Assessment Rating index. (30 class I patients with Begg method and 30 class I patients treated with edgewise method were selected randomly from two separate private clinics). Pre-treatment PAR indices in both groups were comparable. Changes in PAR index after treatment was compared between the two groups. Result was analyzed by general linear model and mANOVA.Results: Sex and age distribution between the two groups were matching. Using PAR index, only improvement in buccal occlusion in Begg group was more significant than edgewise group. Considering total PAR index, no significant difference was obtained between the two groups, although duration of treatment in Begg method was significantly shorter than Edgewise.Conclusion: Occlusal outcomes (total PAR index) were similar in Begg and Edgewise methods. Treatment results by Begg method accomplished in shorter duration than Edgewise treatment.

Introduction: Humans need food to provide energy, growth and development of body. A Standard dietary regimen can be established in childhood with satisfactory general and oral health. The purpose of this study was to analyze the food diet of Mashhad preschool children and its relationship to dental health status in 2005.Materials & Methods: In this descriptive study, 191 randomly selected children (boys and girls), aging 5 to 6 years old from Mashhad kindergartens were evaluated. A 3-day dietary history was recorded to assess children's diet and food guide pyramid was used for analysis. dmft index was also determined. Friedman, Kruskal Wallis, Mann Whitney and Wilcoxon tests and pearson correlation coefficient were used for statistical analysis.Results: The results of this study showed that 59.2%, 47.1%, 49.2%, 1.6% and 24.6% of children consumed recommended amount of meet and beans, fruits, dairy products, vegetables and grains respectively. The data revealed a sufficient consumption of meat and beans but the amount of vegetable consumption was very poor in study group (P<0.001). Mean dmft index was 4.5±4.05 in study group. There was no relationship between each of five main dietary groups and dmft in this study, but there was a reverse correlation ship between the amount of protein and fat consumption with dmft index (P<0.05).Conclusion: In this cross sectional study, there was a reverse relationship between the amount of fat and protein consumption with dmft index. Nutrition has a great effect on oral and dental health status in long time, so conducting longitudinal studies in this field is recommended.

Introduction: Disinfection of dental prostheses is important, so determining an appropriate disinfectant and the effective time for disinfection is necessary. The aim of this study was to evaluate of the disinfecting effect of 0.5% Sodium hypochlorite and 2% Glutaraldehyde on heat cure acrylic resin contaminated by two types of bacteria.Materials & Methods: In this experimental & In vitro study 90 acrylic resin samples, 6mm×17mm, were made using Acropars acrylic resin. The sterilized samples were divided into two groups. One group was exposed to a microbial suspension containing Streptococcus viridance and the other was exposed to a microbial suspension containing Bacillus subtilis. Two negative controls not contaminated with barteria were considered. Two samples from each group were used as the positive controls and were not disinfected. Each group was divided into two subgroups. The subgroups were immersed in either 2% glutaraldehyde or 0.5% sodium hypochlorite. After 30 min, 2h and 4h, seven samples were removed from each solution and transferred to individual tubes containing Brain Heart Inpusion (BHI) culture medium.The tubes were incubated for 24h at 37oC and then examined for turbidity. A sample of each tube was plated onto blood agar plate and the results were observed after 24h. Statistical analysis was made by Chi-Square tests (Fisher's exact test) and Kendalls tau-b.Results: The difference between 3 time interval in all samples for hypochlorite solution (P=0.057) was not significant but it was significant for glutaraldehyde (P=0.021). Comparing 3 time intervals in the samples contaminated with Bacillus subtilis for hypochlorite solution (P=0.032) and glutaraldehyde (P=0.014) showed significant difference. The analysis was not made for Streptococcus viridance because all the results were negative. The difference between the disinfecting ability of the solutions after 30 min (P=1) and 2h (P=0.266) was not significant.Conclusion: The results indicate that both disinfecting solutions eliminated Streptococcus viridance after 30min but could not eliminate Bacillus subtilis until 4h immersion time. Within the number of the samples in this study there was no difference between the disinfecting ability of 0.5% sodium hypochlorite and 2% glutaraldehyde.

Introduction: Lateral cephalometry is mostly used when cephalometric measurements are made from radiographs.However, because of the superimposed images appearing on the lateral cephalograms, reliable measuring of the individual angles (for example Gonial angle) becomes very difficult. How reliable the cephalometric measurements are when determined from an orthopantomogram is the purpose of this study.Materials & Methods: In the first stage of this descriptive analytical study, five different measurements (Gonial angle, FMA, Condyle height, Ramus height and Body length of the mandible) were studied on two dry skulls. The same measurements were made on the panoramic images of these dry skulls and then compared with these measurements in lateral cephalometirc radiography. In the second stage of this study, the same measurements were studied on the panoramic and lateral cephalometry of 101 subjects (52 females and 49 males, mean age of 16). Then the measurements were compared in different growth patterns. For data analysis, the pearson correlation coefficient was used.Results: In comparison of actual measurements obtained from dry skulls and panoramic radiographic measurements, it was revealed that all the five measurements (except length of the body of the mandible) in panoramic radiographs were close to actual degrees in dry skulls. Correlation tests showed the hightest correlation between panoramic and cephalometric radiographs in gonial angle (r=0.89, P<0.001) whereas the least correlation was seen in the length of mandibular body. In different growth patterns, it was seen that gonial angle and ramus height showed the highest correlation between the two radiographs.Conclusion: The ability to determine growth direction from the orthopantomogram will be useful because majority of dentists request an OPG for patients during routine dental examination.

Length of bridge has direct effects on stress of abutments. This study evaluates the changes in pattern and quantity of stress with the pontic length variation. We can use the results to design the dimension of pontic and also in fixed partial denture treatment planning when the load applied to bridge is important.Materials & Methods: In this in vitro study, the finite element method was used to analyze mechanical behavior of prosthesis and its supporting structures when a fixed prosthesis with two designs replaces a mandibular first molar. In finite element stress analysis method, models were designed similar to the actual one with ANSYS computer software.Two PFM bridge models with normal pontic were designed which one of them was 3-unit F.P.D and the other was 4-unit F.P.D. Physical propertics of Ni-Cr-Be alloy, dentine, PDL, spongy and compact bone were determined for the software program. A 700 N load was applied vertically to the center of pontic, and then stress in abutment, bone and prosthesis were analyzed by ANSYS software.Results: Stress concentration was in the mesial of premolar, apex of premolar and distal of molar (13.4 MPa) in the supporting bone of 3-unit F.P.D. Stress pattern in the bone was the same in 3-unit F.P.D and 4-unit F.P.D. When the length of pontic was doubled, stress in the bone was doubled too (26.2 MPa). Stress concentration in 3-unit F.P.D was in distal of premolar (cervical region), mesial of molar (cervical region) and Furca in tooth structure (45.8 MPa).Maximum stress in 3-unit F.P.D prosthesis was respectively in joints (511 MPa), distal margin of premolar and mesial margin of molar. Maximum stress in 4-unit F.P.D was in the joint of two pontic (1903 MPa).Conclusion: When the length of pontic was doubled, stress in the bone was doubled too. Maximum stress concentration in 3-unit F.P.D was in the distal joint. In 4-unit F.P.D, maximum stress was in the joint between the pontics.

Introduction: The success of tooth-colored restorations depends on bonding them to hard tooth tissue that will retain the restoration to the cavity preparation and prevent microleakage. Different adhesive systems have been introduced that provide bonding between tooth-colored filling materials and tooth structure (dentin) that will withstand the contraction forces generated by polymerization shrinkage while maintaining a marginal seal during functioning of the restored tooth. The purpose of this investigation was to study the microleakage of class V resin restorations and the shear bond strength of composite resin to dentin using four different types of current bond adhesive systems.Materials & Methods: This experimental study has been done on 96 intact human premolar teeth extracted for orthodontic purposes within a 3-month period.The teeth were randomly divided into two parts as A and B. In part A, Standardized classic class V cavity dimensions of 3.0 mm (occlusal-gingival), 2.0 mm (mesial-distal), and 2.0 mm (depth) prepared in buccal and lingual surfaces of teeth at the cemento-enamel junction with the cervical margin in dentin or cementum and the occlusal margin in enamel. Enamel Cavosurface margin of cavities were beveled. The cavities were etched with 36% phosphoric acid for 15 second then were rinsed. The cavities were restored with a composite resin (Z100 3M ESPE) using four different dentin adhesive systems [SingleBond (3M-ESPE), Excite (vivadent), One-Step (Bisco), Prime & Bond NT (Dentsply-Detry)]. The specimens' thermocycled for 3000 cycles (5-55°C) and were then immersed in a 10% solution of methylene blue dye for 72 hours. After rinsing, the restorations were sectioned buccolingualy and the microleakages were scored by an optical stereomicroscope with x40 magnification. In part B, the teeth mounted in a 2.5 cm diameter acrylic cylinder mold and buccal surfaces of teeth were ground to expose dentin. After etching and rinsing, the four adhesive systems mentioned before were applied to dentin surface with the wet bonding technique. A cylinder of Z100 dental composite with a 3 mm diameter and 2 mm height was placed on the adhesive covered dentin surface of all groups and light-cured. The specimens were kept in distilled water at room temperature for one week and then thermocycled for 3000 times (5-55oc).Shear bond strength of specimens was measured using an instron universal mechanical testing machine with the cross-head speed of 0.5 mm/minute. Data were analyzed with one way ANOVA, Kruskal-Wallis, Tukey HSD and Mann-Whitney U tests.Results: The mean & standard deviation of shear bond strengths (Mpa) of groups were as follows: One-Step: 19.60±1.83, Single Bond: 21.44±3, Prime & Bond NT: 26.51±5.02, Excite: 29.78±3.85. Analysis of the results revealed that One-step had lowest and Excite had highest shear bond strength (P<0.05). Prime & Bond system had the least and One-Step system had the most microleakage in dentin margins of restorations (P<0.05). Single Bond and Excite bonding systems statistically had no difference in dentin marginal microleakage (P>0.05).Conclusion: Different types of one bottle dentin bonding agents had different micro leakage scores and different shear bond strengths.

Introduction: The knowledge of root canal anatomy and morphology and understanding the cases with variations from the normal anatomy are necessary to achieve success in endodontic. No cases with four separate roots in the mandibular second molars have been reported sofar. The purpose of this study was to report the presence of four separate roots in a mandibular second molar in a patient.Results: A 29 year old male patient was referred for root canal therapy of a mandibular right second molar with a history of emergency treatment. The diagnostic radiograph revealed the presence of four separate roots. The presence of five orifices was confirmed in the pulp chamber after access cavity completion. Conventional root canal treatment was performed in the five root canals of the tooth.Conclusion: The knowledge of common anatomic configurations and possible variations in root canal morphology is one of the important factors for a successful root canal treatment. Report of uncommon cases can motivate the dentist to always perform exact radiographic and clinical evaluations of the teeth and consider the rarities during root canal treatment.