JOURNAL OF ISLAMIC DENTAL ASSOCIATION OF IRAN (MAJALLAH-I-DANDANPIZISHKI)
Year:2014 | Volume:25 | Issue:4 (89)|Papers Count:14

Background and Aim: Tooth fracture is a common complication following MOD restorations. This study sought to assess the effect of different cusp coverage patterns on fracture resistance of maxillary premolar teeth in MOD composite restorations.Materials and Methods: In this in vitro experimental study, 40 human maxillary sound premolar teeth were chosen and stored in Chloramine solution. Using bleaching shield, an over impression was made from each tooth and then wide MOD cavities were prepared. The teeth were randomly divided into 4 groups of 10 each: Group A, without cusp coverage; Group B, with 1.5 mm palatal cusp coverage; Group C, with 1.5 mm buccul cusp coverage; and group D, with 1.5 mm both buccal and palatal cusp coverage. The cavities were restored using Z100 composite resin and the prepared over impressions (in order to restore the normal anatomy of teeth). The teeth were then stored in water at 37oC for 24h and their fracture resistance was assessed using Universal Testing Machine. The load at fracture was recorded in N. Data were analyzed using one-way ANOVA and Tukey’s test with 95% CI.Results: The mean fracture strength was 873.11±243.5 N in group A, 750.53±270.7 N in group B, 824.22±330.2 N in group C and 1499.25±305 N in group D. The results showed that the fracture resistance of MOD restorations with the coverage of both cusps was significantly more than that of other groups (P<0.05).Conclusion: MOD restorations with cusp coverage in maxillary premolar teeth increased the fracture strength of teeth against compressive forces. However, covering only one cusp had no significant effect on fracture strength.

Background and Aim: Application of self-etching bonding systems to primary and permanent teeth has increased due to the simplicity of work and fewer steps. This experimental study aimed to compare the effect of conventional acid etching and single-bottle and self-etching bonding systems on shear bond strength (SBS) of light-cured fissure sealant to primary and permanent enamel.Materials and Methods: In this experimental study, the smoothest unprepared proximal enamel surfaces of 30 primary molars (groups 2, 4 and 6) and 30 permanent premolar teeth (groups 1, 3 and 5) were divided into 6 groups of 10. Groups 1 and 2 (control) were acid-etched and received light-cured fissure sealant (Concise 3M-ESPE). Groups 3 and 4 (SB) were subjected to acid etching + Single Bondadhesive + fissure sealant. Groups 5 and 6 (PLP) received self-etching bonding system (Prompt L-Pop, 3M, ESPE) + fissure sealant. Specimens were then subjected to 500 thermal cycles with the dwell time of 30 seconds. Shear bond strength was determined using Universal Testing Machine (Zwick, Germany). Mode of fracture was determined under stereomicroscope and data were analyzed using ANOVA, (between-subjects effect) and LSD.Results: SBS was not significantly different between the control and PLP or SB and PLP groups (P>0.05). However, the difference in SBS between the control and SB groups was statistically significant (P=0.022). The SBS in primary teeth was less than in permanent teeth in all groups (P<0.05).Conclusion: Self-etching bonding system (PLP), similar to conventional acid etching technique, provides adequate bond between the light-cured fissure sealant and unprepared enamel. Application of Single Bond Adhesiveeffectively increased the fissure sealant bond strength.

Background and Aim: Radiography is the most commonly used technique for root canal length determination; but its application in pedodontics is difficult due to problems namely the radiation hazards, superimposition of permanent teeth buds and uncooperative children. Electronic apex locator (EAL) is used for determination of root canal length. The aim of this study was to assess the accuracy of an Electronic Apex Locator (Ipex) in measuring the root canal length of primary teeth in-vivo.Materials and Methods: This clinical study was conducted on 50 root canals of primary teeth that had to be extracted. After local anesthesia induction and caries removal, access cavities were prepared and the length of root canals was measured using Ipex Electronic Apex Locator. After the extraction of teeth, the actual length of canals was measured using a #15 K file from a reference point. Data were analyzed using paired t-test and intra-class correlation coefficient.Results: The accuracy of Ipex was 20% for accurate determination of actual root canal length, 66% for estimation within ±0.5mm of the apex and 80% for estimation within ±1 mm of the apex. Paired t-test revealed a significant difference between the actual root canal length and the length displayed by Ipex (P<0.001). A direct strong correlation existed between the length measured by Ipex and the actual root canal length (r=0.957).Conclusion: Ipex had a tendency to underestimate the actual root canal length. Since the working length is shorter than the actual root canal length, Ipex may be used for endodontic treatment of primary teeth.

Background and Aim: Coronal seal is as important as the quality of root canal therapy in treatment success. This study aimed to compare the coronal microleakage of canals filled with Resilon and gutta percha with a glass ionomer coronal barrier.Materials and Methods: In this experimental study, the crowns of 64 single-rooted human premolar teeth were cut at the level of CEJ. Root canals were prepared using rotary ProTaper files. The teeth were randomly divided into 4 experimental groups (n=14) and 2 positive and negative control groups (n=8). Root canals of experimental group specimens were filled with gutta percha (groups 1 and 2) or Resilon (groups 3 and 4) using lateral condensation technique. The roots of negative control specimens were filled and all teeth surfaces were sealed with sticky wax. Root canals of positive controls were filled without the application of sealer. Glass ionomer coronal barrier was placed at the orifices in groups 2 and 4. Microleakage of Streptococcus faecalis was evaluated during 90 days. Data were analyzed using Chi square, Log-Rank and Tukey’s tests.Results: The degree of microleakage was less in groups with GI coronal barrier. However, this difference was not statistically significant (P>0.05). Time to microleakage in gutta percha+ coronal barrier and Resilon+ coronal barrier groups was significantly less than that in gutta percha and Resilon groups, respectively (P=0.03).Conclusion: Within the limitations of this study, microleakage occurred in all groups but glass ionomer acted as an effective barrier.

Introduction: Root perforation is an endodontic procedural error. Treatmentof perforation depends on the location and size of perforation, duration of exposure to the oral cavity, patient's cooperation and degree oftissue inflammation. Several materials have been introduced to seal off the perforation. MTA is one of the best materials for this purpose.Case Report: We report the repair of distal root perforation in a primary mandibular second molar of a 9 year-old boy who had congenital absence of the second premolar tooth at the same quadrant. The perforation site was sealed with MTA and the three root canals were filled with gutta percha. Follow up visits at 1, 3, 6, 12, 21 and 24 months showed clinical and radiographic success of treatment.

Background and Aim: Cardiac patients have different dental needs than healthy individuals and clinicians should be well aware of these differences. The aim of this study was to evaluate and compare knowledge, attitude and practice of parents of children with cardiac disease and healthy children.Materials and Methods: In this case-control study, data were collected using a questionnaire. The study population consisted of 25 parents of children with cardiac disease and 25 parents of healthy children selected at a pediatric physician office. Both groups were matched in terms of age, gender and parents’ educational level. Data analysis was performed using independent sample t-test for knowledge and attitude and Mann Whitney test for practice with a=0.05.Results: Based on the parents'' responses, knowledge of parents was 45.24±23.29 in the cardiac group and 41.10±20.45 in healthy group. This difference was not statistically significant. Attitude of parents was 79.3%±9.9 in the cardiac group and 78.9%±6.6 in the healthy group. This difference was not statistically significant either. In the cardiac group, 44% brushed two times a day compared with 20% in the healthy group; 50% of the cardiac children had never visited a dentist while healthy children had regular dental visits.Conclusion: In the fields of knowledge and attitude there were no significant differences between two groups, knowledge of parents in two groups was poor but their attitude was positive also practices of parents in the field of children''s brushing was good but in the field of attending to dentist was poor.

Background and Aim: The Orthognathic Quality of Life Questionnaire (OQLQ) was designed by Cunningham in 2001 to assess the quality of life of patients in relation to orthodontic treatments. This study sought to evaluate the validity and reliability of the Farsi version of OQLQ in 10-14 year-olds in Shiraz.Materials and Methods: This descriptive analytical study was conducted on 240 students in the age range of 10-14 years that were randomly selected from the 4 educational districts in shiraz. One elementary and one middle school were selected from each district. The OQLQ questionnaire contains two sections. The first section asks for demographic information of patients and the second part contains 22 questions regarding the quality of life in relation to dental status. This questionnaire was translated to Farsi using the standard forward-backward translation method. The standardized Cronbach’s alpha, alpha if item deleted, item-total correlation and inter-item coefficients were used for the assessment of the reliability and validity of the questionnaire. For the calculation of test-retest validity, 30 students filled out the questionnaire again 2 weeks after the first session. Mann Whitney U and Chi square tests were used to assess the correlation between the different aspects of the quality of life in the questionnaire and willingness to take the treatment. Data were analyzed using SPSS version 18 software.Results: The internal consistency analysis of the OQLQ indicated a good correlation between questions and domains of the questionnaire. Cronbach’s alpha in this study was 0.86. For the calculation of test-retest reliability of the questionnaire, weighted kappa was found to be 0.91. Mann Whitney U and Chi square tests found significant differences between willingness for orthodontic treatment and dentofacial esthetics (part 2, P=0.008) and knowledge about dentofacial esthetics (part 4, P=0.018).Conclusion: Farsi translation of OQLQ is a suitable tool for the assessment of the effect of dentofacial problems on thequality of life of orthognathic patients in an Iranian population.

Background and Aim: Water pipe smoking has become a public health hazard. The aim of this study was to measure and compare the concentration of salivary cotinine in cigarette smokers, water pipe smokers and nonsmokers.Materials and Methods: Forty-eight volunteers (16 cigarette smokers, 16 water pipe smokers and 16 nonsmokers) participated in this cross-sectional study. High sensitivity Salivary Cotinine Quantitative enzyme immunoassay kit was used to measure the salivary cotinine concentration. Non-parametric Kruskal Wallis test, Pearson’s correlation coefficient and linear regression were used to determine the correlation between number of cigarettes smoked and concentration of cotinine.Results: The mean concentration of salivary cotinine was 223.74 (±181.56) ng/ml (the highest) in cigarette smokers, 106.24 (±135.23) ng/ml in water pipe smokers and 0.73 (±1.24) ng/ml in nonsmokers. The difference in this respect among the 3 groups was statistically significant (P<0.0001). In smokers, the level of salivary cotinine increased by 1.84 ng/ml per each time of cigarette smoking per week. This increase was 14.57 ng/ml per each time of water pipe consumption per week.Conclusion: The mean concentration of salivary cotinine was significantly higher among cigarette smokers compared to water pipe smokers and nonsmokers. However, one time consumption of water pipe caused a greater rise in salivary cotinine level compared to cigarette smoking.

Background and Aim: Finding a relationship between the blood glucose level and its concentration in other body fluids such as the saliva can help in developing a conservative method for blood sugar assessment replacing venous sampling. The aim of this study was to evaluate the relationship of blood glucose level with salivary glucose in diabetic patients.Materials and Methods: This case-control study was conducted on 75 diabetic patients as the case and 75 healthy subjects as the control group. Blood and salivary glucose levels were measured in the two groups. Pearson’s correlation coefficient was used to assess the correlation of blood glucose with salivary glucose in the two groups.Results: The mean (±SD) blood glucose and salivary glucose level was 247±24.2mg/dl and 1.4±0.2mg/dl in the case group, respectively. These rates were 84.97±15.8 and 1.09±0.12mg/dl in the control group, respectively. Statistical analyses showed a high correlation between blood glucose level and salivary glucose in diabetic patients (r=0.9); whereas this correlation was insignificant in the healthy control group (r=0.18).Conclusion: This study showed a high correlation between blood glucose level and salivary glucose in diabetic patients.

Background and Aim: Stem cells due to their great potential can help in establishing tissue engineering as a new treatment modality. Numerous studies have evaluated the effect of various chemical and mechanical stimuli on these cells. In this respect, the role of mechanical loads is undeniable. This systematic review evaluated studies on the effects of mechanical loads on differentiation of mesenchymal stem cells to different cell lineages published in the past 12 years.Materials and Methods: In this systematic review, PUBMED database was used to search key words namely “human mesenchymal stem cell”, “strain,”, “mechanical loading,” and “differentiation”, in the literature published from 2000 to July 2012. The inclusion criteria were the publication year, language of articles, type of cells and study objectives.Results: In total, 46 articles were evaluated qualitatively. In most studies, applied mechanical loads led to the anticipated differentiation. Studies showed that the combination of two forces increased differentiation. The a mount of applied strain also influenced the type of differentiation.Conclusion: This review indicated that advances made on the effects of mechanical loads on stem cells can be used for improving tissue engineering treatments.

Background and Aim: Cone Beam Computed Tomography (CBCT) has the ability to accomplish rapid volumetric image acquisition by its cone-shaped beam. The aim of this study was to evaluate the safety and efficacy of this imaging modality.Materials and Methods: A standard systematic review was performed. Medline (December 2012) and The Cochrane Library (Issue 3 2012) were searched to identify evidence about the performance (sensitivity, specificity and safety) of CBCT compared with other standard diagnostic methods. The results of the included studies were analyzed using a qualitative method.Results: Thirty-one articles were included in the study; the majority of them were diagnostic studies with a small sample size (n<10). There was limited evidence about the effectiveness of this technology and the available evidence was scattered and sometimes controversial. At present, CBCT technology has greatly advanced and its image quality in terms of resolution is higher than that of MOCT. However, its contrast resolution is still lower than that of MOCT. Therefore, MOCT is preferred for soft tissue imaging. For evaluation of hard tissue in the maxillofacial region, a more clear image with higher resolution can be obtained by CBCT.Conclusion: CBCT technology is now commonly used in developed countries for obtaining detailed information regarding the oral and maxillofacial region and can greatly help clinicians in diagnosis and treatment of maxillofacial disorders.

Background and Aim: There is a reduction in bond strength of composite resin to bleached enamel. The aim of the present study was to evaluate the effect of sage (Salvia officinalis) on the shear bond strength of composite resin to bleached enamel.Materials and Methods: In this in vitro study, 60 labial surfaces of maxillary incisors were randomly divided into 4 groups as follows: G1: bleaching; G2: bleaching and application of sodium ascorbate-containing solution; G3: bleaching and application of Salvia officinalis-containing solution; G4: control (no bleaching). A composite resin ( Z100; 3M ESPE, Dental products, St Paul, MN, USA) cylinder was bonded on each specimen after acid etching and application of a fifth generation bonding agent ( Single Bond; 3M ESPE, Dental products, St Paul, MN, USA ). After thermocycling, the shear bond strengths of the samples were measured in MPa. Data were analyzed using one-way ANOVA and Tukey’s HSD test (α=0.05).Results: Minimum and maximum mean values of shear bond strengths were observed in G1 (12.31±2.44) and G3 (25. 04 ± 3.52), respectively. No statistically significant differences were found in bond strength between the bleached and non-bleached groups after the antioxidant treatment (P>0.05).Conclusion: There is a considerable decrease in bond strength of composite resin to enamel immediately after bleaching. Application of sodium ascorbate and Salvia officinalis solution can increase the bond strength of composite resin to bleached enamel.