Amir Reza Rokn, DDS, MSc
Mohammad-Sadegh Ahmad-Akhoundi, DDS, MSc.
Shahroo Etemad-Moghadam, DDS, MSc.
Abbas Mirzaei, PhD
Vol 13, No 5 (2016)
Objectives: The purpose of this study was to determine buccal bone and soft tissue thicknesses and their correlation in the maxillary anterior region using cone beam computed tomography (CBCT).
Materials and Methods: In this cross sectional study, 330 sound maxillary incisors in 60 patients with a mean age of 37.5 years were assessed by CBCT scans. For better visualization of soft tissue, patients were asked to use plastic retractors in order to retract their lips and cheeks away from the gingival tissue before taking the scans. Measurements were made in three different positions: at the crest and at 2 and 5mm apical to the crest. The cementoenamel junction‒crest distance was measured. for data analyses, the Pearson’s correlation coefficient, ANOVA and intraclass correlation coefficient were used.
Results: There were mildly significant linear associations between labial soft tissue and bone thickness in the canines and incisors (r<0.40, P<0.05), but no association was found for the lateral incisors. The mean thickness of buccal bone differed significantly in the maxillary anterior teeth, being greater for the lateral incisors (P<0.05). For soft tissue thickness, the results were the same, and the least thickness was recorded for the canines. There was a mild association between labial soft tissue and bone thickness in canines and incisors (r=0.2, P=0.3), but no such linear association was seen for the lateral incisors.
Conclusions: The mean thickness of buccal bone and soft tissue in the anterior maxilla was <1mm and there was a mild linear correlation between them.
Objectives: With side effects of antibiotics taken into consideration, the necessity of antibiotic therapy after simple implant placement procedures is still a subject of debate and the existing literature on this topic is widely controversial. The aim of this study was to assess the effect of postoperative amoxicillin therapy on early colonization of peri-implant sulcus after implant placement.
Materials and Methods: In this randomized controlled clinical trial, 20 patients requiring simple implant placement were randomly allocated to test or control groups and received postoperative amoxicillin or placebo, respectively. Microbiological samples were collected on day 0 and day 7. Mann Whitney and Wilcoxon signed rank tests were utilized to evaluate changes in colony count of identified bacterial species between the test and control groups, and between day 0 and day 7.
Results: The decrease in the number of sensitive facultative species and the increase in the number of resistant anaerobes in amoxicillin group were statistically significant as compared to the placebo group (P=0.025 and P=0.005, respectively). The increase in the number of sensitive anaerobes in the placebo group as compared to amoxicillin group, and the decrease in the number of facultative Gram-positive cocci as compared to the placebo group were statistically significant (P=0.011 and P=0.035, respectively).
Conclusions: Postoperative administration of amoxicillin resulted in an increase in the number of resistant anaerobes and a decrease in the number of sensitive facultative bacteria and facultative Gram-positive cocci, as compared to the placebo, but with no sign/symptom of infection in any group.
Objectives: This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 seconds on marginal microleakage of composite restorations.
Materials and Methods: Class V cavities (4x2x2mm) were prepared on the buccal surfaces of 64 third molars and randomly divided into four groups of 16. In the control group, Single Bond (SB) adhesive was applied after etching. In BB+SB group, after application of BisBlock (BB) desensitizer agent (which needs etching), SB adhesive was used. In BB+5E+SB group, re-etching of dentin was done for five seconds after application of desensitizer, and then the adhesive was applied. The process in BB+10E+SB was the same as BB+5E+SB group except for re-etching time, which was 10 seconds. The cavities were restored with composite resin. After 24 hours of storage in distilled water and 10,000 thermal cycles, all samples were subjected to dye penetration test. The teeth were sectioned buccolingually in the middle of restorations. A blind examiner observed the sections under a stereomicroscope.
Results: At the occlusal margins, no significant difference in microleakage was observed among the groups (P>0.05). Application of BB in combination with SB had no effect in comparison to the control group (P>0.05); while there were significant differences in microleakage scores between BB+10E+SB and control (P=0.002), BB+10E+SB and BB+SB (P<0.001) and BB+5E+SB and BB+SB groups (P=0.009).
Conclusions: Dentin re-etching after application of BB desensitizer increased the gingival microleakage of class V composite restorations. Application of BB desensitizer combined with SB adhesive enhanced marginal seal.
Objectives: Periodontal tissue regeneration for treatment of periodontal disease has not yet been mastered in tissue engineering. Stem cells, scaffold, and growth factors are the three main basic components of tissue engineering. Periodontal ligament (PDL) contains stem cells; however, the number, potency and features of these cells have not yet been understood. This study aimed to isolate and characterize the properties of PDL stem cells.
Materials and Methods: In this experimental study, samples were isolated from the PDL of extracted teeth of five patients and then stained immunohistochemically for detection of cell surface markers. Cells were then examined by immuno-flow cytometry for mesenchymal markers as well as for osteogenic and adipogenic differentiation.
Results: The isolated cell population had fibroblast-like morphology and flow cytometry revealed that the mesenchymal surface markers were (means): CD90 (84.55), CD31 (39.97), CD166 (33.77), CD105 (31.19), CD45 (32/44), CD44 (462.11), CD34 (227.33), CD38 (86.94), CD13 (34.52) and CD73 (50.39). The PDL stem cells also differentiated into osteoblasts and adipocytes in osteogenic and adipogenic media, respectively.
Conclusions: PDL stem cells expressed mesenchymal stem cell (MSC) markers and differentiated into osteoblasts and adipocytes in osteogenic and adipogenic media, respectively.
Objectives: This study sought to evaluate the accuracy and errors of linear measurements of mesiodistal dimensions of Kennedy Class III edentulous space using cone beam computed tomography (CBCT) in comparison with clinical measurements.
Materials and Methods: Nineteen Kennedy Class III dental arches were evaluated. An impression was made of each dental arch and poured with dental stone. The distance was measured on dental cast using a digital Vernier caliper with an accuracy of 0.1mm and on CBCT scans. Finally, the linear mesiodistal measurements were compared and the accuracy of CBCT technique was evaluated by calculating absolute value of errors, intra-class correlation coefficient and simple linear regression model.
Results: In comparison with the cast method, estimation of size on CBCT scans had an error of -8.46% (underestimation) to 5.21% (overestimation). In 26.5% of the cases, an accepted error of ±1% was found. The absolute value of errors was found to be in the range of 0.21-8.46mm with an average value of 2.86 ±2.30mm.
Conclusions: Although the measurements revealed statistically significant differences, this does not indicate a lower accuracy for the CBCT technique. In fact, CBCT can provide some information as a paraclinical tool and the clinician can combine these data with clinical data and achieve greater accuracy. Undoubtedly, calibration of data collected by clinical and paraclinical techniques and the clinician’s expertise in use of CBCT software programs can increase the accuracy of implant placement.
Objectives: Masking ability of a restorative material plays a role in hiding colored substructures; however, the masking ability of zirconia ceramic (ZRC) has not yet been clearly understood in zirconia-based restorations. This study evaluated the effect of three different core materials on masking ability of a ZRC.
Materials and Methods: Ten zirconia disc samples, 0.5mm in thickness and 10mm in diameter, were fabricated. A white (W) substrate (control) and three substrates of nickel-chromium alloy (NCA), non-precious gold alloy (NPGA), and ZRC were prepared. The zirconia discs were placed on the four types of substrates for spectrophotometry. The L*, a*, and b* values of the specimens were measured by a spectrophotometer and color change (ΔE) values were calculated to determine color differences between the test and control groups and were then compared with the perceptual threshold. Randomized block ANOVA and Bonferroni test analyzed the data. A significance level of 0.05 was considered.
Results: The mean and standard deviation values of ΔE for NCA, NPGA, and ZRC groups were 10.26±2.43, 9.45±1.74, and 6.70±1.91 units, respectively. Significant differences were found in the ΔE values between ZRC and the other two experimental groups (NCA and NPGA; P<0.0001 and P=0.001, respectively). The ΔE values for the groups were more than the predetermined perceptual threshold.
Conclusions: Within the limitations of this study, it was concluded that the tested ZRC could not well mask the examined core materials.
Objectives: This in-vitro study aimed to compare the push-out bond strength of composite to prepared and unprepared intracanal dentin using a 5th generation bonding agent in primary anterior teeth after etching for seven and 15 seconds.
Materials and Methods: Sixty primary anterior teeth were randomly divided into four groups. In groups one and two, intracanal dentin remained intact while in groups three and four it was prepared using a #5 round bur and low-speed handpiece. Single Bond 2 was used in groups one and three after 15 seconds and in groups two and four after seven seconds of etching with phosphoric acid. After restoring with composite resin and incubation, the specimens were subjected to push-out bond strength test. Data were analyzed using two-way ANOVA and Kaplan Meier curves.
Results: The mean bond strength was not significantly different between seven and 15 seconds etching times (P=0.198). Dentin preparation had no significant effect on the mean bond strength (P=0.838). The interaction effect of etching time and dentin preparation was not significant either (P=0.680).
Conclusions: Decreasing the etching time from 15 to seven seconds and preparation of intracanal dentin had no significant effect on push-out bond strength of composite to intracanal dentin of primary anterior teeth.
Objectives: New digital two-dimensional imaging systems are considered as an easily accessible modality for sinonasal evaluation. The aim of this study was to assess the diagnostic efficacy of digital Waters’ and Caldwell’s radiographic views for evaluation of sinonasal area.
Materials and Methods: A total of 273 patients fulfilling the inclusion criteria were enrolled in this descriptive-analytical study. Complete opacification or mucosal thickening of frontal, ethmoidal and maxillary sinuses and nasal septum deviation were assessed on digital Waters and Caldwell images. Considering cone beam computed tomography (CBCT) as the gold standard, accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were obtained for the plain films.
Results: The sensitivity and specificity for the diagnosis of complete opacification were 89.47% and 95.66% (for frontal sinus), 100% and 97.59% (for ethmoidal air cells), and 100% and 96.42% (for maxillary sinuses), respectively. Regarding mucosal thickening, the sensitivity and specificity were 51.43% and 90.70% (for frontal sinus), 60.84% and 84.80% (for ethmoidal air cells) and 81% and 74.74% (for maxillary sinuses), respectively. The sensitivity of Waters and Caldwell images for detecting nasal septum deviation was 84.31% and 87.25%, respectively; whereas, their specificity was 100%.
Conclusions: Digital Caldwell image performs well in detecting frontal and ethmoidal opacification and nasal septum deviation. It has moderate efficacy in assessing frontal and ethmoidal mucosal thickening while it has superior performance for detection of healthy cases. Digital Waters’ view is a reliable modality for maxillary sinus evaluation.
Objectives: The purpose of the present study was to evaluate the effect of modified Widman flap (MWF) surgery (as a periodontal treatment procedure) on maximum bite force (MBF; as an indicator of patient function).
Materials and Methods: In this clinical trial, 24 patients were examined for their MBF before and at one, four and eight weeks after their MWF surgery. These recordings along with the patients’ demographics were analyzed using repeated measures ANOVA at a significance level of 0.05.
Results: Males had a significantly higher MBF than female patients. Repeated measures ANOVA revealed a significant difference in MBF among the four time points (P<0.001) in each gender group. The MBFs recorded at baseline, and at four and eight weeks were not significantly different (P=0.148). Also, MBF showed a slight increase in male patients while it decreased in females over time.
Conclusions: The MWF surgery does not eventually decrease patients’ MBF, which is a relief for patients. This procedure is therefore advised in order to save the maximum number of teeth as it remains the most significant factor determining MBF. However, this surgery has more favorable results in male patients. At four weeks after surgery, the patients will regain their baseline bite force.
Objectives: This study sought to assess the effect of curcumin nanoparticles (curcNPs) on antimicrobial property and shear bond strength (SBS) of orthodontic composite to bovine enamel.
Materials and Methods: In this in vitro, experimental study, 1%, 5% and 10% curcNPs were added to Transbond XT composite. Stainless steel brackets were bonded to 48 sound bovine incisors in four groups (n=12) using composite containing 0% (control), 1%, 5% and 10% curcNPs. The bracket-tooth SBS was measured by a universal testing machine. The adhesive remnant index (ARI) score was calculated after debonding using a stereomicroscope. Also, 180 discs were fabricated of the four composites; 108 were subjected to eluted component test, 36 were used for disc diffusion test and 36 were used for biofilm test to assess their antimicrobial activity against Streptococcus mutans, Streptococcus sanguinis and Lactobacillus acidophilus.
Results: The highest and lowest SBS belonged to control and 10% curcNP groups, respectively. The difference in SBS was significant among the four groups (P=0.008). The SBS of control group was significantly higher than that of 10% curcNPs (P=0.006). The four groups were not significantly different in terms of ARI score (P>0.05). Growth inhibition zones were not seen in any group. In biofilm test, the colony counts of all bacteria significantly decreased by an increase in percentage of curcNPs. Colony count significantly decreased only at 30 days.
Conclusions: At 1% concentration, curcNPs have significant antimicrobial activity against cariogenic bacteria with no adverse effect on SBS. However, insolubility of curcNPs remains a major drawback.
Amir Reza Rokn, DDS, MSc
Mohammad-Sadegh Ahmad-Akhoundi, DDS, MSc.
Shahroo Etemad-Moghadam, DDS, MSc.
Abbas Mirzaei, PhD
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