JOURNAL OF ISLAMIC DENTAL ASSOCIATION OF IRAN (MAJALLAH-I-DANDANPIZISHKI)
Year:2007 | Volume:18 | Issue:4 (61)|Papers Count:17

Background and Aim: Fluoride is the most important mineral in the prevention of tooth caries. This study evaluated the relationship between salivary pH levels, fluoride baseline concentration in saliva and dmft index in 5-year-old children attending kindergartens in Hamadan, during 2004.Materials and Methods: A total of 200 children (100 male and 100 female), 5 years of age were selected for this cross sectional study. The dmft indices were determined through examination of all subjects using a dental mirror and explorer under natural light. 100 children (50 male and 50 female) were divided into 2 groups: dmft>l and dmft<l which constituted the case and control groups, respectively. Approximately 1-3 ml unstimulated saliva was collected from each subject and fluoride concentration was measured in ppm using a fluoride ion selective electrode. The pH of all samples was assessed by a pH meter. The data were analyzed using T-test.Results: Fluoride concentration and salivary pH levels were 0.0113±0.007ppm and 6.74±0.28 in the case group and 0.0321±0.011 ppm and 6.53±0.44 in the control group, respectively. A statistically significant relationship was observed between the baseline fluoride and pH levels of saliva and dmft indices.Conclusion: According to these results an appropriate concentration of fluoride in the saliva and an increased pH can reduce the dmft index in children.

Background and Aim: In PFM restorations, marginal coverage of the metal framework with porcelain, without producing an over contoured margin is necessary to enhance esthetics. The aim of this study was to evaluate the marginal integrity of porcelain fused to base metal crown after extension of porcelain to the border of the margin.Materials and Methods: Thirty brass standard dies were prepared and divided into 3 groups of 10, based on different finishing lines: 90° shoulder, 1.2-mm-wide; 135° slopping shoulder, 1.2-mm-wide; and shoulder, 0.7-mm-wide with a 45° bevel, 0.5 mm-long. For each die a brass cap was fabricated according to the specific finishing line to accommodate a 0.5 mm thickness. Two metal copings were made on each die which were used as test and control samples. The marginal gap of each coping was measured at 4 points under a reflective microscope after casting and oxidation. Porcelain was applied and extended to the border of the margins in the test group and 0.5 mm short of the borders in the control group. Marginal gaps were measured once more at the same points after porcelain firing. Statistical analysis was performed using t-test.Results: The marginal gaps of all copings increased after porcelain firing. Extension of porcelain to the border of the margins did not significantly increase the marginal gaps.Conclusion: These results indicated that porcelain can be extended to the border of the crown's margin without producing a significant increase in the marginal gap.

Background and Aim: The use of mouthwashes for plaque control and preventing its accumulation on teeth and adjacent mucous membranes is of considerable importance. The aim of this investigation was to compare the effectiveness of chlorhexidine and two Irsha mouthwashes, on aerobic microorganisms in oral flora. Materials and Methods: In this in vitro study, the diffuse-agar method was used to effects of antiplaque-antitartar Irsha mouthwash, antiseptic Irsha mouthwash and 0.2% chlorhexidine on oral aerobic microorganisms. The microorganisms were dispersed and plated on blood agar or Muller Hintone medium. Six-millimeter paper disks immersed in each of the study solutions were inserted into the plates after the incubation period. This procedure was repeated 4 times for each of the microorganisms and the inhibition zones were measured for each microorganism and mouthwash, separately. The data were analyzed using ANOVA and Tukey HSD (post hoc) tests. Results: Antiplaque Irsha was useful in controlling some of the analyzed microorganisms including lactobacilli, Neisseria sicca, C. diphtheroid, Streptococcus salivarius, Streptococcus viridans and Streptococcus mutans, in decreasing order. Antiseptic Irsha did not affect the aerobic bacteria. Chlorhexidine was effective on all complex infections consisting of the studied aerobic microorganisms, especially lactobacilli and Staphylococcus epidermidis.It also successfully controlled Staphylococcus aureus followed by Brevudimonas, Neisseria sicca, Streptococcus salivarius, Streptococcus mutans, Pseudomonas aeruginosa and Streptococcus viridans, in that order.Conclusion: According to these results, 0.2% Chlorhexidine demonstrated a superior antimicrobial effect in most cases as compared to the studied mouthwashes.

Background and Aim: An increase in pH can affect the erosive potential of soft drinks, but the possible role of calcium salts and phosphate has not been fully recognized. The aim of the present investigation was to evaluate the effect of pH on the erosive potential of soft drinks on permanent tooth enamel.Materials and Methods: This experimental in vitro study was performed on 8 beverages and 240 intact premolars extracted for orthodontic purposes. Two Iranian soft drinks (Cola and Orange Zamzam) and 2 imported ones (Pepsi and Mirinda) constituted the case group and 4 solutions with the same pH served as the control group. The teeth were divided into 3 groups (A, Band C) and further subdivided into 8 subgroups and immersed in 20 ml of one of the 8 beverages for 15minutes (A), 45 minutes (B) and 12hours (C). The amount of Ca++ released in each soft drink or solution was estimated by AA-spectrophotometry at the end of each exposure time.Results: A statistically significant difference was found in the extent of erosion between the case and control groups which increased with exposure time (P<0.001). The pattern of Ca++ concentration changes were similar in both study groups (p=0.3915), but the case group revealed a higher erosive potential than the control group (P<0.001).Conclusion: The percentage of titratable acids seems to have a greater effect on the erosive potential of beverages when compared to pH. Measuring pH alone could not accurately estimate the erosive potential of different soft drinks.

Over the past 20 years, the number of edentulous adults has declined in developed countries. Considering the increase in the general populations' life span, the need and demand for complete dentures is becoming more widespread, especially in our country with the high prevalence of edentulous.Despite the advances in dental materials and improved technological and clinical expertise, yet there are many patients experiencing difficulties in wearing removable dentures such as pain, discomfort, loss of retention, gagging, reduced taste sensation and problems related to speech, esthetics and function. Many of these issues are due to faulty or incorrect diagnosis, inaccurate treatment planning or mechanical deficiencies such as inappropriate denture design. Also, physical and psychological problems may contribute either directly or indirectly to a patient's inability to use the prosthesis. This makes it necessary for practitioners to have a general perception of the causes, diagnosis and treatment of these problems.The purpose of this investigation was to review the various problems associated with denture wearing which may be immediate, short-term or long-term and also to identify their cause, diagnosis and treatment.

Background and Aim: Fusion and gemination (double teeth) are developmental anomalies of unknown etiology. It is not always possible to differentiate clinically between these two abnormalities. The presence of primary double teeth may cause problems in the permanent dentition. The purpose of this study was to determine the prevalence of fusion and gemination in the primary dentition of 3-5 year-old kindergarten children in Tehran.Materials and Methods: In this cross-sectional study, several kindergartens located in Tehran, Rey, and Shemiranat were randomly selected and 1000 children with an age range of 3-5 years were examined.Results: The prevalence of double teeth was %0.8 from which %87.5 showed fusion and %12.5 revealed gemination. All fusions were observed in the mandible and all geminations in the maxilla. Double teeth were distributed evenly among both sexes, but when considered separately, %57 of the fusions were observed in girls and all geminations in boys. The most common double teeth were the central and lateral incisors which occurred in the mandible. Gemination of the primary lateral incisor was observed in %12.5 of the double teeth and was encountered in the maxilla. Further examination of the permanent dentition was performed in a number of cases and aplasia of the permanent lateral incisor and succedaneous teeth were observed in these subjects, which were due to fusion of the lateral primary incisor and canine.Conclusion: Considering that primary double teeth may be followed by problems in the permanent dentition, early diagnosis and continuous monitoring of successors is suggested to avoid further complications.

Introduction: Fusion and Gemination are developmental anomalies of the dental hard tissue. The preferred terminology for these two abnormalities is "double teeth".Case Report: A 10 year-old boy presented with a "double" maxillary permanent left central incisor. In clinical and radiographic examination, a large crown with two distinguishable roots and pulp spaces was observed. Double teeth usually need a multidisciplinary approach.Because of the communication found between the pulp spaces, endodontic treatment was performed followed by periodontal surgery to remove one of the roots and its corresponding crown. Finally, restorative and orthodontic treatment was provided.

Background and Aim: In clinical practice it is commonly assumed that occlusal splints have therapeutic value in the treatment of temporomandibular disorders (TMD), however there is still lack of sufficient evidence to support this claim. The purpose of this double-blind study was to evaluate the short-term (8-week) efficacy of a stabilization splint in subjects with temporomandibular disorders seeking treatment.Materials and Methods: Seventeen TMD patients were treated with stabilization splints for eight weeks. In addition to filling out questionnaires, all patients underwent a preoperative and postoperative clinical-functional investigation of the masticatory system. Qualitative data were analyzed using Fisher exact and Chi-square tests and Wilcoxon signed ranks test was applied to report quantitative data.Results: A statistically significant decrease was observed postoperatively in the Helkimo clinical dysfunction index (P=0.000) as well as the anamnestic dysfunction index (P=0.020). In addition there was a statistically significant decrease in muscle tenderness, after treatment (P=.002).Conclusion: The results of this study indicate that the use of a stabilization splint is beneficial in treatment of the signs and symptoms of TMD, and especially has a positive effect on muscle tenderness.

Background and Aim: One of the most important factors in the development of periradicular disease and endodontic failure is infection through the root canal. Apically-extruded debris may be considered a major causative agent of flare-ups and post-instrumentation pain. This in vitro study compared the reduction of intracanal bacteria and the amount of apically extruded debris (AED) using RaCe and FKG systems.Materials and Methods: Sixty extracted mandibular single-canal premolars were selected for this experimental investigation. 0.5 mm-deep grooves were made around all teeth at a 0.5mm distance from their apices. Sixty vials (7ml) were prepared and preweighed to 0.0001 precision. Each tooth was mounted in a rubber stopper and then fitted into the openings of the vials. All equipment were sterilized by ethylene-oxide and the canals were inoculated with E. faecalis. The samples were then incubated for 24 hours at 37°C in sealed chambers. During canal instrumentation, irrigation was performed with 2 ml normal-saline after each file size. Following preparation, the apical portions of the canals were sampled using sterile paper-points and the bacterial colonies were counted (CFU/ml). The vials were weighed again to obtain the amount of AED. Non-parametric Mann-Whitney U-test was used for statistical analysis. Results: A significant difference was not observed between the RaCe and FKG systems regarding E. faecalis elimination and debris extrusion (P=0.1 and P=0/17, respectively).Conclusion: The two studied systems could not completely eliminate E. faecalis.

Background and Aim: Formocresol is an inrtacanal medicament commonly used for pulpotomy in the primary dentition. Because of its toxic and carcinogenic potential, it has been challenged by other chemical treatments. The purpose of this study was to histologically assess the pulpal healing process in pulpotomized primary teeth, using two different agents: formocresol and ferric sulfate.Materials and Methods: A total of 16 primary cuspids (8 pairs) from 8 patients who were scheduled for orthodontic extraction were selected and randomly divided into 2 groups. One tooth from each pair of contralateral teeth was assigned to either formocresol or ferric sulfate pulpotomy. Four pairs were extracted after 1 month and the other 4, after 2 months. Pulpal response was determined according to the degree of inflammation and extent of pulpal involvement. Dentinal bridge formation was also evaluated. The data were analyzed using Wilcoxon test.Results: No significant difference was found between the two groups for inflammation, absecess, root resorption and dentinal bridge formation. Necrosis was more extensive in the formocresol pulpotomy group (p<0.05). Conclusion: Based on these results, formocresol can be substituted with ferric sulfate for pulpotomy of primary teeth.

Background and Aim: The use of CarisolvTM decreases unnecessary removal of sound dental tissue and reduces the possibility of pulpal exposure. However, it is expensive and time-consuming and its efficacy has not been clearly defined. The aim of this study was to compare the efficacy, safety and efficiency of removing deep caries using conventional mechanical methods alone and in conjunction with Carisolv.Materials and Methods: This investigation was a single-blind randomized clinical trial. Forty individuals, each with a deep carious tooth (0.5-1 mm from the pulp) without signs and symptoms of necrosis or irreversible pulpitis were selected and randomly divided into two study-groups: A, all caries were mechanically removed using rotary instruments and B, Carisolv was applied on deep carious lesions and the rest of the caries were mechanically eliminated. All cavities were evaluated by a dental probe. After complete caries removal the teeth were filled as usual. The outcome variables were complete caries removal, pulpal exposure and time taken to remove caries. The results were analyzed by X2 and Mann-Whitney tests.Results: Three pulpal exposures occurred in group A and one in group B without a statistically significant difference. Regarding complete caries removal, the two methods were similar. The mean caries-removal time was 16±6.8 min in group A and 25.2±6.3 min in group B (P<0.001). The amount of Carislov used for each tooth was 0.17 cc.Conclusion: Application of the mechanical and chemomechanical methods simultaneously, is more time-consuming and does not seem to significantly improve the treatment results.

Background and Aim: NiTi rotary instruments have been extensively used in the preparation of curved root canals, due to their superelastic quality, These instruments are less susceptible to unexpected fracture as compared to their stainless steel counterparts. However, unexpected fracture of NiTi instruments under complex stress within curved canals can lead to serious problems. The aim of this investigation was to identify and evaluate the various failure mechanisms which can cause fracture of NiTi rotary instruments under clinical conditions.Materials and Methods: The causes of failure of two brands of Hero and Profile rotary files have been studied. A total of 1133 instruments that failed during clinical use were collected from several dental clinics, after inspection under a stereomicroscope, all instruments were classified as either plastically deformed or fractured. The fracture surfaces of all broken instruments were examined following ultrasonic cleaning in ethanol and acetone, 30 minutes each. The fracture surfaces of more than 70 broken instruments were subjected to fractographic analysis using a scanning electron microscope. Results: More than 68% of the 1133 specimens were fractured. Stereomicroscopic inspection showed three failure mechanisms for the studied instruments: fracture, plastic deformation due to bending and torsion and a combination of both mechanisms. Based on fractographic observations, microvoid coalescence and cyclic stable crack growth by striation formation were identified.Conclusion: According to these results, excessive plastic deformation and fracture may be considered as the two main mechanisms responsible for the failure of NiTi rotary instruments.

Background and Aim: Light-cured composites have become almost universal in modem clinical dentistry. Unfortunately, these materials have demonstrated critical limitations such as postoperative sensitivity and polymerization shrinkage. The aim of this study was to evaluate the effects of three curing modes on the microleakage of class V composite restorations.Materials and Methods: In this experimental in vitro study, class V cavities were prepared on the buccal surfaces of 90 extracted human molar and premolar teeth and were randomly divided into 3 groups. All teeth were etched followed by bonding and composite filling. Three different methods were used for curing: conventional, 750 mw/cm2/40s; pulse delay, 400 mw/cm2/5s-5 minutes delay-750 mw/cm2/35s; and soft start, beginning at 150 mw/cm2 and increasing to 750 mw/cm2 during 15 seconds and remaining for another 35 seconds. After polishing, the specimens were stored in a 37°C incubator, thermocycled (500 cycles) and immersed in basic %0.5 fushin. Longitudinal buccolingual sections of all teeth were scored for marginal dye penetration under a stereomicroscope. Kruskal-Wallis test was used for statistical analysis.Results: Leakage was observed in all groups but no significant difference was found in the microleakage scores among the three light-curing techniques, used in this investigation.Conclusion: These findings suggest that the 3 studied light-curing methods may have no effect on the microleakage of class V posterior composite restorations.

Background and Aim: Salivary contamination during application of bonding agents may adversely affect adhesive/dentin bond strength. This investigation evaluated the effect of salivary contamination on the shear bond strength of three different bonding systems without treatment.Materials and Methods: Seventy-two intact posterior extracted human teeth were used in this interventional in vitro study. The tested materials consisted of ScotchBond MP (SBMP), SingleBond (SB) and Prompt which are considered as three-step, fourth generation; two-step, fifth generation and one-step, sixth generation bonding agents, respectively. For each tooth, the enamel on the buccal surface was removed by a diamond disc. Specimens were assigned to 12 groups according to the studied adhesives: SBMP into 5, SB into 4 and Prompt into 3 groups. Dentin surfaces were contaminated with natural saliva for 5 seconds. Cylinders of composite were applied onto the dentin surfaces using plastic cylindrical molds. The shear bond strength of the specimens was determined with an Instron testing-machine at a crosshead speed of 0.5 mmlmin. The results were analyzed by one-way ANOVA and Tukey HSD tests.Results: A significant difference was not observed between the contaminated SBMP and SB groups, but the difference between the contaminated and uncontaminated specimens was significant. In the Prompt groups, the difference between the contaminated and uncontaminated samples was not significant. No significant difference was found between the shear bond strengths of the adhesives, except for Prompt and SBMP.Conclusion: Shear bond strength depends on the type and structure of the applied adhesive and the stage at which salivary contamination occurs.

Background and Aim: Combining the durability of amalgam and the esthetic appearance of composites can improve the quality and longevity of dental restorations. The aim of this study was to evaluate the effect of amalgam etching on microleakage at the cervical margins and the junction between amalgam and composite.Materials and Methods: In this experimental study 20 extracted sound maxillary premolars were used. Two class II cavities were prepared on the mesial (group A) and distal (group B) surfaces of each tooth. Group A cavities were restored with amalgam on the floor of the cavity and after etching the enamel walls, a self-cure bonding agent was applied followed by composite insertion. The same protocol was followed for group B cavities except that the etchant was placed on both amalgam and enamel walls. The teeth in each group were either stored for I week or 6 months in normal saline, then thermocycled for 1000 cycles (2±4°C and 54±4°C) and finally immersed in 2% fushin for I week. Marginal leakage was assessed by the degree of dye penetration on sections of the restored teeth, under a stereomicroscope (x10). Data were analyzed using Mann Whitney V-test (p<0.05). Results: None of the specimens showed microleakage in the amalgam-composite interface. No statistically significant difference was observed in microleakage between the two groups after I week and after 6 months. The study groups did not show a significant difference regarding storage time.Conclusion: Amalgam ethching had no significant effect on the microleakage of combined amalgam-composite restorations.