Volume 17

Published: 2020-07-31

Review Article

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    Objectives: The aim of this systematic review was to assess the clinical efficacy of bone regeneration for treatment of peri-implantitis.
    Materials and Methods: Electronic search of the literature was performed to identify randomized clinical trials (RCTs) and case series on treatment of peri-implantitis using bone regeneration procedures with at least 6 months of follow-up. The guidelines of the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) were applied. The risk of bias was assessed using the Cochrane Collaboration’s Risk of Bias tool.
    Results: Two RCTs and 16 case series with a total of 520 treated patients (2002 implants) were included. Bone regenerative procedures showed controversial results regarding bone fill. Two studies reported statistically significant bone gain while four studies reported insignificant bone gain. Other studies reported bone gain with no P value. Pocket depth (PD) reduction varied among the studies since four studies reported a significant reduction in PD while four others reported insignificant reduction in PD. Other studies reported a reduction in PD with no P value. Bone regeneration procedures seemed to decrease bleeding on probing (BOP) but they did not seem conducive to increase the width of keratinized gingiva. Increased keratinized gingiva was noted in cases with subepithelial grafts.
    Conclusion: Evaluation of the effectiveness of bone regeneration techniques in this systematic review presented limitations related to heterogeneity in patient selection (age, history of periodontitis, smoking status and implant system), means of disinfection and decontamination, and variability of the materials used for treatment.

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    This study assessed the efficacy of the retromandibular antero-parotid approach for open reduction and internal fixation (ORIF) of subcondylar fractures. Sixty patients with the mean age of 31.03 years underwent surgical reduction with a 20-25mm incision in the retromandibular area with an antero-parotid transmasseteric approach. All patients were followed between 6 to 12 months. At the end of the first week, six patients exhibited postoperative malocclusion. At the next visits, all patients had optimal occlusion. Maximal interincisal opening (MIO) of 56 patients (93.3%) was >37mm, and only four patients (6.7%) had MIO<37mm. In three patients (5%), weakness of the buccal branch of the facial nerve was noticed postoperatively. No salivary gland complications were seen. The surgical scar was hardly noticeable. Retromandibular access with transmasseteric antero-parotid approach is the technique of choice for treatment of high- and low-level subcondylar fractures with adequate visibility and direct access to the condylar area.

Original Article

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    Objectives: Bulk fill composites are preferred to conventional composites with time-consuming incremental application technique, given that they have good mechanical properties and low microleakage. The aim of this study was to evaluate and compare the dentinal marginal microleakage of bulk fill (in two viscosities) and conventional composites in class II cavities in maxillary premolars.
    Materials and Methods: In this in vitro studyˏ 42 class II cavities were prepared in the mesial and distal surfaces of 21 maxillary premolars extending 1 mm below the cementoenamel junction, and restored with Grandio composite with 2-mm increments, and X-tra fil and X-tra base with 4-mm increments. After 24 h of storage at 37oC and 100% humidity, they were thermocycled (500 cyclesˏ 5-55oC), stored in basic fuchsine, sectioned, and evaluated under a stereomicroscope (×40). The microleakage scores of the gingival margin were recorded. Statistical analysis was done by SPSS 21 via the Kruskal-Wallis and Mann-Whitney U tests at P≤0.05 level of significance.
    Results: No statistically significant differences were noted among the groups in marginal microleakage (P=0.47). No statistically significant difference was noted between bulk and incremental application techniques in this respect either (P=0.23).
    Conclusion: There was no difference in marginal microleakage between the bulk fill and conventional composites.

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    Objectives: This study aimed to evaluate the fracture resistance of over flared endodontically treated bovine central incisors restored with prefabricated and custom-made glass fiber posts, using the multi-post approach. 
    Materials and Methods: Sixty-eight crownless over flared endodontically treated incisors were used for this study. The depth of prepared post space was 10 mm, and the remaining dentin thickness of the roots was 1 mm. The samples were randomly divided into four groups (n=17): Group 1: two prefabricated glass fiber posts; group 2: prefabricated glass fiber post + braided glass fiber; group 3: braided glass fiber; group 4: no post. Static load was applied at a crosshead speed of 0.5 mm/min at 135º angle relative to the root longitudinal axis until fracture. The data were analyzed using one-way ANOVA and post hoc Tukey’s test at a significance level of P<0.05.
    Results: Groups 3 and 4 exhibited the maximum (981 N) and minimum (461 N) fracture strength values, respectively. The differences between group 4 and other groups were significant (P<0.001), but the differences between groups 1, 2, and 3 were not significant (P>0.05).
    Conclusion: Multiple prefabricated and custom-made glass fiber posts significantly increased the fracture resistance of crownless endodontically treated central incisors with over flared root canals.

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    Objectives: Glass ionomer cements (GICs) are among the most popular dental restorative materials, but their use is limited due to their clinical disadvantages. Many efforts have been made to improve the properties of these materials by adding various fillers. Incorporation of hydroxyapatite (HA) into the GICs is considered to improve the physical properties of restorations, and may prevent treatment failure. This study aimed to evaluate the surface roughness (Ra) of a conventional glass ionomer cement (CGIC), a resin-modified glass ionomer (RMGI) and a Zirconomer with and without micro-hydroxyapatite (µHA).
    Materials and Methods: This experimental study was conducted on 6 groups (n=10) including CGIC, CGIC + µHA, RMGI, RMGI + µHA, Zirconomer, and Zirconomer + µHA. A total of 60 disc-shaped samples (6 mm × 2 mm) were prepared in plastic molds and were stored in distilled water for 24 h. After polishing of the specimens, their Ra was measured by a profilometer in micrometers (µm). The data were analyzed using two and one-way ANOVA, Tukey's HSD test, and independent t-test.
    Results: Incorporation of µHA resulted in statistically significant differences in Ra between the study groups (P<0.05). Following the incorporation of µHA, the Ra significantly decreased in CGIC (P=0.013) and Zirconomer (P=0.003). However, addition of µHA to RMGI resulted in a significant increase in its Ra (P<0.001).
    Conclusion: Addition of µHA decreased the Ra of Zirconomer and CGIC, and increased the surface roughness of RMGI samples.

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    Objectives: This study aimed to evaluate the degree of conversion (DC%), shear bond strength (SBS), bond durability, and the resin-dentin interface of polydopamine (PDA) incorporated total-etch adhesive system.
    Materials and Methods: Five percentage by weight (wt%) concentration of PDA incorporated adhesive was prepared and its polymerization was evaluated using Fourier-transform infrared spectroscopy. The results were compared with the DC% of conventional total-etch adhesive (Adper Single Bond 2) using independent t-test. Occlusal surfaces of 80 freshly extracted human premolars were sectioned to expose the dentin, which was acid-etched. The samples were divided into two groups (n=40) of total-etch adhesive and total-etch adhesive+PDA. Composite resin blocks were built up over the bonded surface and cured. Each group was subdivided into two subgroups (n=20) of immediate and post-aging evaluation. Samples were immersed in 10% sodium hypochlorite for five hours, and then, the SBS was evaluated using a universal testing machine at a crosshead speed of 1 mm/minute. The resin-dentin interface was evaluated using confocal laser scanning microscopy. Data were analyzed using two-way analysis of variance and post-hoc Bonferroni test.
    Results: DC% was not affected by the addition of 5% PDA to the adhesive (group 2). The SBS of group 2A was significantly higher than that of group 1A. There was no significant reduction of SBS in group 2B. The hybrid layer was less degraded after aging in group 2B compared to group 2A.
    Conclusions: PDA incorporated adhesive increased the immediate bond strength and durability without changing the DC%.

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    Objectives: This study aimed to assess the effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) on microtensile bond strength of three adhesive systems to deep dentin.
    Materials and Methods: In this in vitro study, the occlusal surface of 30 sound human third molars was sectioned at 2 mm below and above the cementoenamel junction. The samples were randomly divided into three groups of OptiBond Solo Plus, G-Bond, and Clearfil SE Bond. Before composite resin bonding, each group was divided into two subgroups with and without dentin preparation with CPP-ACP. The teeth were then sectioned into 1 mm rods (n=15), and their microtensile bond strength was measured at a crosshead speed of 0.5 mm/min. Data were analyzed using two-way ANOVA and post-hoc Bonferroni test.
    Results: There was no significant difference in bond strength of OptiBond Solo Plus (P=0.44) and Clearfil SE Bond (P=0.67) with/without CPP-ACP. A significant difference was found between the two subgroups of G-Bond in this respect (P<0.001). The differences in microtensile bond strength among all subgroups were significant (P<0.05).
    Conclusion: The microtensile bond strength in use of G-Bond is significantly higher following dentin treatment with CPP-ACP compared with no use of CPP-ACP.

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    Objectives: This study evaluated the effect of two educational interventions on knowledge and self-reported practice of mothers of 8-year-old children regarding emergency management of traumatic dental injuries (TDIs).
    Materials and Methods: Six public elementary schools (girls and boys) in Tehran were randomly selected. The mothers of 8-year-old students at each school were randomly assigned to three groups: intervention by poster, intervention by pamphlet, and control. An anonymous valid and reliable questionnaire, including demographics, previous experience on TDIs, mothers’ knowledge, and self-reported practice about emergency management of TDIs was provided to the mothers. After collecting the questionnaires, educational interventions by poster and pamphlet with similar contents regarding step-by-step emergency management of TDIs were performed for the target groups. Three months after the interventions, the same questionnaire was completed by the mothers. The results of pre-test and post-test were compared.
    Results: Totally, 201 mothers participated in this study. The mean knowledge score significantly increased in the pamphlet group after the intervention, while this change was not significant in the poster and control groups (P>0.05). The mean knowledge score was significantly higher in the pamphlet group than the poster group (P=0.009). The mean self-reported practice score significantly increased after the intervention in both intervention groups (P<0.05) but not in the control group. There was no significant difference in the mean self-reported practice score between the two intervention groups (P>0.05).
    Conclusion: Both pamphlet and poster were equally effective in improving the self-reported practice of mothers regarding TDIs, which highlights the significance of educating mothers.

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    Objectives: Bacterial leakage at the implant-abutment interface is one of the main causes of peri-implant inflammation. One of the factors that influences bacterial leakage is the structural design of the interface. Considering the limited studies that have examined slip-joint connections, a comparative study of bacterial leakage was performed on two different systems namely Zimmer (Tapered Screw-Vent, Zimmer Dental) with slip-joint connection and Argon (Konus K3pro, Argon Implants) with conical connection.
    Materials and Methods: Twenty-two implants were selected in 2 groups (11 Zimmer with slip-joint connection, and 11 Argon with conical connection) with similar platforms. Escherichia coli (E. coli) suspension (2 μL) was pipetted into the internal lumen of implants. The abutments were screwed onto the implants with a closing torque of 30 Ncm. The assemblies were placed in culture broth for 6, 24, 48 and 72 h, and 7 and 14 days. The colonies were counted and analyzed by the Mann-Whitney test (a=0.05).
    Results: Microleakage was observed in 20% of the samples of conical connection group after 6 h to 2 days, and in 50% of the samples in slip-joint connection group after 3 to 7 days. There was a significant difference in bacterial leakage rate between the two implant groups (P<0.001) but no significant difference was seen in bacterial leakage over time (P>0.05).
    Conclusion: Type of connection had a significant effect on bacterial leakage, but the rate of bacterial leakage did not significantly change over time.

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    Objectives: Inadequate removal of the hemostatic agent can adversely affect the bond strength of restorations to the tooth structure. This study aimed to assess the effect of different cleansing protocols on the shear bond strength (SBS) of an etch-and-rinse adhesive to dentin contaminated with aluminum chloride hemostatic agent.
    Materials and Methods: In this experimental study, the mid-coronal dentin of 96 premolars was exposed. They were contaminated with a hemostatic agent (ViscoStat Clear) and then randomly divided into 7 groups (n=12). One group served as the control. The groups underwent various cleaning methods as follows: water spray, aluminum oxide particles (27µ diameter), a slurry of pumice with water, GC dentin conditioner (GCDC), sodium hypochlorite 2% (SHC), and chlorhexidine 2% (CHX). Composite cylinders were then fabricated and bonded to the surfaces using Scotchbond Multi-Purpose etch-and-rinse bonding agent. After thermocycling (10,000 cycles), the SBS was measured using a universal testing machine. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey HSD (honestly significant difference) test, and the significance level was set at 0.05.
    Results: The SBS of the groups was significantly different (P=0.036). The SBS was the highest in the CHX and SHC groups, and the lowest SBS was related to the control group and GCDC groups. The difference between other groups was not significant (P=0.996).
    Conclusion: CHX and SHC yielded the highest bond strength among the tested modalities for cleansing the ViscoStat Clear from the tooth surface.

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    Objectives: This study aimed to assess root canal transportation of curved canals following glide path preparation by PathFile and Scout RaCe rotary systems compared with manual instrumentation with stainless steel (SS) hand files using cone-beam computed tomography (CBCT).
    Materials and Methods: This in-vitro experimental study was conducted on extracted human mandibular first and second molars (n=51) with 25-45° canal curvature in their mesiobuccal root. All teeth underwent CBCT and were randomly divided into three groups (n=17). In group 1, a glide path in the mesiobuccal canal was created using SS hand files to the working length. In groups 2 and 3, after canal negotiation with a #8 SS hand file, a glide path was created with PathFile and Scout RaCe systems, respectively. The teeth underwent CBCT. Pre- and postoperative CBCT scans were compared to calculate the magnitude of canal transportation at 3, 6, and 9 mm from the apex. The results were analyzed using the Kruskal-Wallis and Freedman tests (P<0.05).
    Results: Manual instrumentation caused significantly higher canal transportation at 3 and 9 mm from the apex compared with rotary systems (P<0.05). PathFile and Scout RaCe were not significantly different at 3 (P=0.39) or 9 mm (P=0.99). No significant difference was noted in canal transportation among the three groups at 6 mm (P=0.15).
    Conclusion: Scout RaCe and PathFile cause less canal transportation than manual instrumentation with SS files when used for glide path preparation in curved canals, especially in the apical third.

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    Objectives: Considering the ever-increase use of vital bleaching procedures and an increase in the use of newly introduced resin-based materials for the restoration of teeth, this in vitro study was designed to evaluate the effect of 15% carbamide gel on the flexural strength of three resin-based restorative materials.

    Materials and Methods: Three different types of restorative materials, Beautifil II giomer, Cention N and Z250 micro-hybrid composite resin, were evaluated in the current study. Twenty-four bar-shaped samples were prepared from each restorative material, totaling 72 samples, and randomly assigned to two groups: with and without bleaching procedures (n=12). In the groups with a bleaching procedure, 15% carbamide peroxide gel was applied 8 hours a day for 14 days. The flexural strengths of the samples were determined. Two-way ANOVA and post hoc Tukey test were applied to compare the flexural strengths of the samples.

    Results: There were significant differences in the flexural strengths of the materials in terms of the exposure to the bleaching agent (P<0.05), with significantly higher flexural strength in the groups without a bleaching procedure. However, the mean flexural strengths were not significantly different in terms of the restorative material (P=0.12).

    Conclusion: It was concluded that 15% carbamide peroxide bleaching gel significantly decreased the flexural strengths of Beautifil II giomer, Cention N and Z250 micro-hybrid composite resin. There were no significant differences in the mean flexural strengths between the three resin-based restorative materials, irrespective of the use or no use of 15% carbamide peroxide gel.

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    Objectives: Implant-supported restorations are generally used for the replacement of the lost teeth. Stability against masticatory forces and proper retention are critical for optimal durability of restorations. The aim of this experimental study was to compare the retention of cobalt-chromium (Co-Cr) copings made by different techniques.
    Materials and Methods: Twenty-four solid abutment analogs were mounted and scanned with a desktop scanner. They were divided into two groups (n=12) and received metal copings fabricated by either soft or hard Co-Cr alloy. Soft Cera­mill Sintron Co-Cr patterns were milled and sintered. Hard Co-Cr blocks were milled in a milling machine. The copings were sandblasted, polished, adjusted, and placed on the respective abutments. The frequency of adjustments was recorded for each abutment. The copings were cemented with zinc phosphate cement and underwent tensile test by a universal testing machine. The Mann-Whitney test and t-test were used to compare the two groups (α=0.05).
    Results: There was no significant difference in retention of copings between the experimental groups. The mean retentive force was 559.58±115.66 N and 557.13 ±130.48 N for the soft and hard metal groups, respectively (P=0.96). Considering the non-normal distribution of adjustment frequency data, the Mann-Whitney test showed that the frequency of adjustments was significantly higher in the hard metal group than the soft metal group (9.5 versus 0.1667; P<0.001).
    Conclusion: Although hard metal copings required more adjustments, retention of soft and hard Co-Cr copings was not significantly different. 

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    Objectives: Predictive analysis can be used to evaluate the enormous data generated by the healthcare industry to extract information and establish relationships amongst the variables. It uses artificial intelligence to reveal associations not suspected by the healthcare professionals. Tobacco cessation is clearly beneficial; however, many tobacco users respond differently as it is based on multitude of factors.  Our objectives were to assess the data mining techniques using the WEKA tool, evaluate its role in predictive analysis, and to predict the quit status of patients using prediction algorithms in tobacco cessation. 
    Materials and Methods: WEKA, a data mining tool, was used to classify the data and evaluate them using 10-fold cross-validations. The various algorithms used in this tool are Naïve Bayes, SMO, Random Forest, J-48, and Decision Stump to further analyze its role in determining the quit status of patients. For this, secondary data of 655 patients from a tobacco cessation clinic were utilized and described using 20 different attributes for prediction of quit status.
    Results: The Decision Stump and SMO were found to be having the best prediction and accuracy for prediction of the quit status. Out of 20 attributes, previous quitting attempt, type of intervention, and number of years since the habit was initiated were found to be associated with early quitting rate.
    Conclusion: This study concluded that data mining and predictive analytical models like WEKA tool will not only improve patient outcomes but identify variables or a combination of variables for effective interventions in tobacco cessation.

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    Objectives: Achieving durable restorations with adequate strength in severely damaged primary anterior teeth in children is a priority. The aim of this study was to investigate the effect of dentin pretreatment with chlorhexidine on push-out bond strength of composite restorations.
    Materials and Methods: In this in vitro experimental study, 56 extracted primary anterior teeth were randomly divided into 4 groups: (1) saline and total-etch bonding agent, (2) chlorhexidine and total-etch bonding agent, (3) saline and self-etch bonding agent, and (4) chlorhexidine and self-etch bonding agent. After the application of bonding agents, the post space was filled with Z250 composite resin. Following thermocycling of the samples, the push-out test was performed using a universal testing machine, and the results were analyzed with two-way ANOVA.
    Results: The mean push-out bond strength values in groups 1 to 4 were 5.7, 8.39, 5.35, and 7 MPa, respectively. Chlorhexidine groups had significant differences with saline groups in bond strength (P<0.05) but there was no statistically significant difference between the self-etch and total-etch bonding agents in the groups (P>0.05).
    Conclusion: Both types of bonding agents (self-etch and total-etch) exhibited favorable results in radicular dentin of primary anterior teeth; however, pre-treatment with chlorhexidine increased the push-out bond strength of composite restorations in primary anterior teeth.

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    Objectives: This study aimed to evaluate the effects of hydrofluoric acid (HF) concentration and etching time on the surface roughness (SR) and three-point flexural strength of Suprinity and to analyze the surface elements before and after etching.
    Materials and Methods: To measure the SR, 70 specimens of Suprinity (2×4×5mm3) were assigned to seven groups (n=10). Six groups were etched for 20, 60, and 120 seconds with 5% and 10% HF and 7th group was the control group. Specimens were evaluated using atomic force microscopy (AFM). One specimen from each group was used to analyze the surface elements using scanning electron microscopy (SEM). For measuring the three-point flexural strength, 60 specimens were divided into six groups (n=10) and etched as previously described. The flexural strength was measured using a universal testing machine. T-test, one-way analysis of variance (ANOVA), and two-way ANOVA were used for statistical analyses (P<0.05).
    Results: The 10% concentration of HF caused higher SR compared to the 5% HF. The effect of HF concentration on the flexural strength was significantly different in the 20- and 60-second etching groups. Different etching times had no significantly different effect on the SR. With 5% HF, the flexural strength was significantly higher for 20-second etching time than for the etching times of 60 and 120 seconds. With 10% HF, there was a significant difference in flexural strength between etching times of 20 and 120 seconds. 
    Conclusions: The best surface etching protocol comprises 10% HF used for 20 seconds.

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    Objectives: The success of implant treatment depends on many factors affecting the bone-implant, implant-abutment, and abutment-prosthesis interfaces. Stress distribution in bone plays a major role in success/failure of dental implants. This study aimed to assess the pattern of stress distribution in bone and abutment-implant interface under static and cyclic loadings using finite element analysis (FEA).
    Materials and Methods: In this study, ITI implants (4.1×12 mm) placed at the second premolar site with Synocta abutments and metal-ceramic crowns were simulated using SolidWorks 2007 and ABAQUS software. The bone-implant contact was assumed to be 100%. The abutments were tightened with 35 Ncm preload torque according to the manufacturer’s instructions. Static and cyclic loads were applied in axial (116 Ncm), lingual (18 Ncm), and mesiodistal (24 Ncm) directions. The maximum von Mises stress and strain values ​​were recorded.
    Results: The maximum stress concentration was at the abutment neck during both static and cyclic loadings. Also, maximum stress concentration was observed in the cortical bone. The loading stress was higher in cyclic than static loading.
    Conclusion: Within the limitations of this study, it can be concluded that the level of stress in single-unit implant restorations is within the tolerable range by bone.

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    Objectives: This study aimed to assess the relationship of frontal sinus height and width with the cervical vertebral maturation (CVM) for assessment of skeletal maturity.
    Materials and Methods: This retrospective study evaluated lateral cephalograms of 132 patients between 8 to 21 years, including 66 males and 66 females. For each of the six stages of the CVM, 22 patients (11 males and 11 females) were evaluated. The Ertuk’s method was used to measure the height and width of the frontal sinus. The sinus height to width ratio was calculated and considered as the sinus index. The CVM was evaluated on the same lateral cephalograms using the Baccetti’s method. The correlation of frontal sinus height and width with the CVM was analyzed, and comparisons were made using independent t-test, ANOVA, Mann-Whitney test, and Kendall's tau-b correlation coefficient.
    Results: The sinus width was 10.85±2.7 mm in males and 9.47±2.6 mm in females. The sinus index was 2.43±0.37 in males and 2.66±0.32 in females (P<0.000). The frontal sinus index and width were significantly greater in males but the sinus length was not significantly different between males and females (P=0.383). Significant differences were found in stages 2 and 3, and also 4 and 5 in females and 2 and 3, 3 and 4, and 4 and 5 in males. The mean frontal sinus index had a significant correlation with the CVM stage in both groups. 
    Conclusion: According to the results, the frontal sinus index cannot be used as a predictor of skeletal maturity. 

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    Objectives: The purpose was to evaluate the impact of an oral health promotion program including supervised toothbrushing and educational packages for parents on parent’s knowledge and oral health status of 6- to 7-year-old schoolchildren.
    Materials and Methods: A multi-stage cluster random sampling method was applied, and schools were allocated to intervention and control groups. After ethical clearance and baseline evaluation, an intervention package consisting of supervised toothbrushing at the school setting, an educational package for parents, and a home package containing toothbrush and fluoridated toothpaste (1000 parts-per-million) were delivered. A post-intervention evaluation was performed after one month on parents’ oral health knowledge and oral hygiene of children using the Oral Hygiene Index Simplified (OHI-S). Schools were considered as a unit of randomization, and a generalized estimating equation (GEE) analysis was performed to apply the cluster effect. Descriptive and analytical analyses were performed using SPSS 22 software.
    Results: Overall, 701 subjects were re-examined (response rate of 95%). At the one-month follow-up, being in the intervention group (P<0.001, B=-0.028, 95% confidence interval (CI)=-0.33, -0.23) and having higher socioeconomic status [P=0.01, B=-0.12, 95% CI=-0.22, -0.03) were significantly associated with improved oral hygiene status. In the post-test evaluation, parents’ knowledge improvement score regarding oral health in the intervention group was not statistically different from that of the controls (0.51 vs. 0.23). However, the ∆OHI-S improved in the post-test evaluation (-0.27±0.02 vs. 0.02±0.02; P<0.001).
    Conclusion: Children showed improved oral hygiene status, as measured by the OHI-S, after the program consisting of supervised toothbrushing.

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    Objectives: This study aimed to evaluate an innovative internship course at health centers for final-year dental undergraduates and to report initial students’ perceptions.
    Materials and Methods: The Department of Community Oral Health, Faculty of Dentistry with the collaboration of the Vice-Chancellor of Health of Babol University of Medical Sciences prepared an educational and clinical training course, named Health Centers Dental Rotation (HCDR), in January 2014. Final year (6th year) dental undergraduates were divided into groups of two or three and worked as an operator or assistant at 12 health centers (six rural and six urban). Students had to fulfill the educational and therapeutic requirements for three weeks. Students' perspectives related to the course objectives were recorded using a five-point Likert scale with a voluntary anonymous questionnaire.
    Results: Forty-four dental students, 26 (60%) females and 18 (40%) males, provided oral health care services at the health centers. Based on the students' perspectives, almost all students (95%) realized the limitations of the health centers. The HCDR improved the awareness of 75% of the students about oral health needs and problems of patients referring to these centers. Although 68% of the students declared that participating in this course was a valuable educational experience, 38.6% described it as displeasing.
    Conclusion: From the students' perspectives, this course was a worthwhile and positive internship experience and provided an opportunity for students to understand the specific oral health needs of patients attending these health centers and to realize their key role in the oral health system.

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    Objectives: This study aimed to compare the sling and single interrupted sutures regarding dehiscence, probing pocket depth (PPD), and clinical attachment loss (CAL) of adjacent second molars after surgical extraction of impacted or semi-impacted mandibular third molars.
    Materials and Methods: This randomized clinical trial, with a split-mouth design, involved 25 patients with similar bilateral impaction of their mandibular third molars. The same surgeon performed surgical procedures, including a triangular flap and osteotomy. After surgical extraction of third molars, the distal surface of the flap was sutured with sling sutures on one side and single interrupted sutures on the other side. The allocation of suture type to the side of the jaw was random, and the patient was blinded to it. Patients were examined for dehiscence after 7 and 14 days. The PPD and CAL were recorded at the baseline and after 17 weeks. Data were analyzed using the Wilcoxon signed-rank test and generalized estimating equation (GEE) regression model.
    Results: The sling suture was significantly superior regarding the improvement of PPD (P=0.041) and CAL (P=0.016). The dehiscence was significantly smaller in the single interrupted suture group 7 days postoperatively (P=0.059). This difference was not significant 14 says postoperatively (P=0.852).
    Conclusion: The results of this study show that the sling suture was superior to the single interrupted suture regarding PPD and CAL. However, the technique of suturing does not seem to have a significant long-term effect on wound dehiscence.

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    Objectives: This study assessed the antimicrobial efficacy of silver nanoparticles (AgNPs) incorporated in Transbond XT orthodontic adhesive used in rats.
    Materials and Methods: Transbond XT orthodontic adhesive containing 0%, 1%, 5% and 10% AgNPs was experimentally produced. Twenty-eight male Wistar rats were randomly divided into four groups (n=7) of control (0% AgNPs), 1% AgNPs, 5% AgNPs and 10% AgNPs. After anesthetizing the rats, one drop (10 μm) of the adhesive was applied on the central incisor, and light-cured for 20 s. Transbond XT composite (1×1×1 mm) was also applied. Another 10-μm drop was applied over it, and light-cured for 40 s. Biofilm test was carried out, and the number of colony forming units (CFUs) of Streptococcus sanguinis (S. sanguinis), Streptococcus mutans (S. mutans) and Lactobacillus acidophilus (L. acidophilus) in the saliva of rats was counted at baseline and 24 h after the application of adhesive. The data were analyzed using one-way ANOVA and Tukey’s test.
    Results: In presence of 5% and 10% AgNPs, S. sanguinis and L. acidophilus counts were significantly lower than those in the control and 1% AgNP groups (P<0.05). The S. mutans colony count was significantly lower in presence of all concentrations of AgNPs compared with the control group (P<0.05). The S. mutans colony count in 10% AgNP group was significantly lower than that in 1% and 5% AgNP groups (P<0.05).
    Conclusion: Silver nanoparticles have dose-dependent antimicrobial effects; 5% concentration is the minimum concentration of AGNPs with optimal antimicrobial efficacy against all strains evaluated in this study.

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    Objectives: The purpose of this investigation was to evaluate the color alteration of dental enamel following the use of light-cured and chemically cured composites for bonding of metal brackets.
    Materials and Methods: Sixty extracted human premolars divided into five groups (n=12) were included in this study. Metal brackets were bonded using chemically cured (System 1+ and Unite) and light-cured (Transbond XT and Grengloo) composites. The control group remained untreated. After 72 hours of immersion in a staining solution and 24 hours of photoaging, the brackets were debonded, and adhesive remnants were cleaned using a 12-blade tungsten carbide bur and polished with Sof-Lex discs. The color was assessed at the baseline and after cleaning procedures in accordance with the CIE L*a*b (lightness, red/green, blue/yellow) color system. Statistical analyses were performed using paired sample t-test and one-way analysis of variance (ANOVA).
    Results: The L*, a*, and b* parameters showed a significant increase in all adhesive groups (P<0.001). The experimental groups showed significant color changes (P<0.05), and the mean ΔE ranged from 2.46 to 3.15 units. No significant difference was found between the ΔE of the adhesive groups (P>0.05).
    Conclusion: The enamel color change is influenced by bonding and debonding procedures. Chemically cured and light-cured composites have similar effects on dental enamel color alterations.

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    Objectives: This study aimed to determine the minimum inhibitory concentration (MIC) of mouthwashes prepared from neem and mango extracts against Streptococcus mutans (S. mutans) in vitro. Their taste acceptability and effects on plaque index (PI), gingival index (GI) and salivary pH were also evaluated and compared with chlorhexidine (CHX) in children.
    Materials and Methods: Dry extracts of neem and mango twigs were prepared and their MIC against S. mutans was determined. The effective MIC was used to prepare mouthwashes from the two extracts. Three parallel groups of children (n=30) used either neem, mango or 0.2% CHX mouthwash for 21 days. The PI and GI were recorded at baseline and at 7 and 21 days. The salivary pH and taste acceptability were also assessed.
    Results: The MIC of both extracts was achieved at 25% concentration. There was a significant difference between the GI score of mango group compared with neem and CHX at the three time points (P<0.001). There was no significant difference between the neem and mango groups in PI (P=0.674). There was no significant difference among the three groups in salivary pH either (P=0.817). Intragroup comparison showed significant reductions in PI, GI and salivary pH in all the three groups after 21 days (P<0.001).
    Conclusion: Neem and mango mouthwashes can be used as effective alternatives to CHX in children.

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    Objectives: Damages to the middle third of the facial bone generally involve the orbital skeleton and can lead to eye impairment. In this study, it is attempted to determine the incidence of ophthalmic injuries in maxillofacial trauma with zygomatic bone fractures.
    Materials and Methods: One hundred and fifteen cases with ophthalmic (ocular) involvement after maxillofacial trauma were referred to the Shariati Hospital, Tehran, Iran, and were visited at the Ophthalmology Department between 2016 and 2018. Zygomatic fractures and resulting ocular complications were evaluated in 87 males and 28 females with the mean ages of 26 and 32 years, respectively.
    Results: Subconjunctival ecchymosis was detected in 23.07% of men and 21.05% of women. Displacement of the palpebral fissure was detected in 26.5% of men and 27.6% of women. Furthermore, the unequal pupillary level was observed in 18.37% of men and 15.78% of women. Diplopia was detected in 8.9% of men and 10.5% of women. Additionally, enophthalmos was observed in 23.1% of men and 25% of women.
    Conclusion: The most common ocular presentations in midfacial trauma are diplopia and reduced visual acuity. Even after the operation, a significant number of patients experience poor vision and diplopia. Ophthalmology consultation is essential for these patients. 

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    Objectives: Fracture of endodontically treated restored teeth is a common concern. Premolars are subjected to high shear and tensile forces. This study aimed to assess the fracture resistance and fracture mode of endodontically treated premolars restored with direct and indirect onlay restorations.
    Materials and Methods: In this in-vitro experimental study, 45 human maxillary premolars were divided into three groups (n=15) of control (sound teeth), direct onlay, and indirect onlay. In groups 2 and 3, the teeth underwent endodontic treatment. Mesio-occluso-distal cavities were prepared and restored with direct composite (P60) and indirect IPS e.max ceramic onlays, respectively. The teeth were subjected to vertical forces after cyclic loading. The maximum load causing fracture was recorded in Newtons. Data were analyzed using analysis of variance, chi-square test, and Tukey’s test.
    Results: The highest and the lowest fracture resistances were noted in sound teeth and direct onlay restorations, respectively. The difference in fracture resistance was significant among the three groups (P<0.001). Pairwise comparisons revealed a significant difference in the fracture resistance of sound teeth and the two restoration groups (P<0.001). However, the difference in the fracture resistance of direct and indirect onlay restorations was not significant (P=0.6). Chi-square test showed a significantly higher frequency of irreparable fractures in the indirect onlay group (P=0.005).
    Conclusion: Direct and indirect onlay restorations were not significantly different in terms of the fracture resistance but the frequency of irreparable fractures was higher in indirect restorations.

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    Objectives: The purpose of this study was to determine the mini-plate and screw removal rate and reasons in maxillofacial surgery patients under previous semi-rigid fixation treatment in the past five years at the main trauma center of Mashhad.
    Materials and Methods: This was a census-based retrospective study. All the candidates who admitted to our department for maxillofacial plate removal due to symptomatic or infected mini-plates were included in this study. The patients’ age and gender, plate removal etiologies, and the time between plate insertion and removal were analyzed.
    Results: Mini-plates were inserted for 1026 patients. However, only 94 patients with a mean age of 29.4±11.1 years were candidates for plate removal. The plate removal rate was 9.16%. Infection and exposure were the most common causes of plate removal. The most prevalent removal site was the mandible (angle and body). The interval between mini-plate insertion and removal was an average of 12.9±5.6 months. It is noteworthy that the shortest lasting duration was when plate removal was secondary to pain (6.67 months) and infection (11.45 months).
    Conclusion: This research showed that the routine removal of plates does not appear to be generally indicated in healthy subjects unless there is an obvious and definitive clinical indication.

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    Objectives: Oral candidiasis has increased in recent years because of the increasing number of high-risk populations. The prevalence of Candida species is different worldwide because of the difference between population characteristics, sampling protocols, and geographic regions. Therefore, determining the more prevalent Candida species in different geographic regions seems essential. This study aimed to determine the more prevalent Candida species in acute myeloid leukemia (AML) patients in comparison with healthy individuals in Iran in 2016.
    Materials and Methods: Fifty-one patients with AML and 62 healthy controls participated in this cross-sectional study. Samples were collected using a swab rubbed softly on the dorsal surface of the tongue and the oropharynx. The samples were cultured on CHROMagar Candida for 2 to 4 days. For differentiation between albicans and non-albicans species, positive samples were linearly inoculated on Corn Meal Agar with Tween-80. Candida species were identified using a microscope. Data were analyzed using chi-square and Fisher’s exact tests.
    Results: Candida colonization was more frequent in AML patients (41.2%) in comparison with healthy participants (38.7%). Candida glabrata (C. glabrata; 27.5%) and Candida albicans (C. albicans; 32.3%) were the most common isolated species in the AML patients and the controls, respectively. There was a significant decrease in the frequency of C. albicans (P=0.022) and a significant increase in the frequency of C. glabrata (P=0.002) in the AML patients in comparison with the controls.
    Conclusion: AML patients are more susceptible to candidiasis. C. glabrata is the dominant Candida species in AML patients.

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    Objectives: This study aimed to evaluate the mucograft collagen matrix (CM) to increase keratinized tissue around teeth compared to free gingival graft (FGG).
    Materials and Methods: The present double-blind, randomized, controlled clinical trial studied 12 patients who had 2 mm or less keratinized gingiva bilaterally around mandibular premolars. The 6-month width of keratinized tissue, periodontal parameters (preoperatively and 1, 3, and 6 months postoperatively), color match, pain, and total surgical time were measured.
    Results: The mean dimensional change of keratinized gingiva 6 months postoperatively was 4.1±0.7 mm for FGG and 8±1.7 mm for CM. Periodontal parameters were not affected in the two groups. The CM group had a significantly lower pain, experienced less surgery time, and gained better aesthetics compared to the FGG group.
    Conclusion: CM appears to be a suitable substitute for FGG in procedures designed to increase keratinized tissue around teeth. It has remarkable benefits, such as acceptable keratinized tissue gain, less pain, less surgical chair time, and better aesthetics.

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    Objectives: This study aimed to compare the oral health related quality of life (OHRQoL) of patients using conventional dentures versus implant-supported overdentures.
    Materials and Methods: This study evaluated the OHRQoL of 90 patients between 35 to 75 years who were selected from several public and private dental clinics in Tehran in 2018. Of all, 45 had conventional dentures of both jaws, and 45 had a mandibular overdenture supported by two implants at the site of mandibular canine teeth and a conventional maxillary denture. The OHRQoL of patients was determined using the Oral Health Impact Prfile-20 (OHIP-20). The questionnaire was translated to Persian, and its content validity and internal consistency were confirmed. Data were analyzed by one-way ANOVA, Mann-Whitney test, and independent t-test.
    Results: In the conventional denture group, 46.7% had good, 46.7% had moderate, and 6.6% had poor OHRQoL. These values were 55.6%, 37.8% and 6.6% in the overdenture group, respectively. Level of education had a significant correlation with the total score of OHIP-20 in both groups (P<0.05). But no significant association was noted between the residential status and gender of patients with different domains of OHRQoL (P>0.05) except for the psychological disability domain, which had a higher mean value in males with conventional dentures (P<0.05).
    Conclusion: Patients with a mandibular overdenture supported by two implants at the site of canine teeth and a conventional maxillary denture had higher OHRQoL than patients with conventional dentures of both jaws.

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    Objectives: This in-vitro study aimed to evaluate the effect of cavity disinfection with chlorhexidine (CHX) on marginal gaps of Class V composite resin restorations bonded with a universal adhesive using self-etch and etch-and-rinse bonding strategy.
    Materials and Methods: Sixty sound human premolars were randomly assigned to two groups (n=30): group 1 (CHX) and group 2 (no CHX). Each group was divided into two subgroups (n=15) according to the bonding strategy of the universal adhesive (self-etch or etch-and-rinse). Class V cavities were prepared on the buccal surfaces of the teeth. The occlusal and gingival margins of the cavities were placed in enamel and dentin, respectively. In the first and second subgroups of both groups, the All-Bond Universal adhesive was applied with self-etch and etch-and-rinse bonding strategy, respectively. After restoration and thermocycling, the samples were sectioned, and marginal gaps at the gingival margins were measured in micrometer (µm) under a stereomicroscope. Two-way analysis of variance (ANOVA) was used to compare marginal gaps between the groups and the subgroups.
    Results: The mean marginal gap size was significantly affected by cavity disinfection (P=0.001) and bonding strategy (P=0.002). However, the interaction effect of these two factors on the mean marginal gap size was not significant (P=0.79).
    Conclusion: The use of CHX resulted in larger marginal gaps at the gingival margins of Class V composite resin restorations. Irrespective of disinfection, the self-etch bonding strategy resulted in larger marginal gaps compared to the etch-and-rinse bonding strategy.

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    Objectives: This study aimed to determine the microtensile bond strength (μTBS) of a bulk-fill composite to permanent and primary coronal dentin using a universal adhesive in self-etch and total-etch modes.
    Materials and Methods: This in-vitro study was performed on 52 occlusal dentinal surfaces of human primary and permanent teeth. The crowns were cut to the gingival level. The 48 prepared dentin sections were randomly assigned to the following groups (n=13): A: Primary/Total-etch, B: Primary/Self-etch, C: Permanent/Total-etch, and D: Permanent/Self-etch. In groups A and C, after etching for 15 seconds, two layers of a universal bonding (Futurabond U) were applied and cured for 10 seconds. All samples were filled with a bulk-fill composite (x-trafil; VOCO) and cured for 40 seconds. The samples were cut to a bar-shaped dentin block with the dimensions of 1×1×1 mm3, and after 10,000 thermocycles, the μTBS test was accomplished at a crosshead speed of 1 mm/minute. The mean and standard deviation (SD) of μTBS were calculated, and the data were analyzed using two-way analysis of variance (ANOVA) and Fisher's exact test.
    Results: The mean μTBS was as follows: A: 15.03±2.0279, B: 11.11±2.4423, C: 23.50±4.8165, and D: 16.26±6.3200 MPa. Futurabond U showed a higher μTBS in the total-etch mode (P<0.001). The permanent teeth had greater μTBS than the primary teeth (P<0.001). Similar percentages of failure modes were observed in the total-etch groups but in the self-etch groups, most failures were in the form of adhesive and mixed.
    Conclusion: Greater μTBS was observed in the permanent teeth with 

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    Objectives: Bone remodeling after tooth extraction results in decreased ridge volume and complicates implant placement. Platelet-rich fibrin (PRF) is a rich source of autogenous cytokines and growth factors; it has been proven to effectively improve soft tissue healing and hard tissue regeneration. This study sought to compare the clinical application of freeze-dried bone allografts (FDBA) and PRF for alveolar ridge preservation after tooth extraction.
    Materials and Methods: This clinical trial was conducted on 32 patients presenting for the extraction of hopeless non-molar teeth. The teeth were extracted with minimal trauma, and the samples were randomly divided into two groups (n=16). Tooth sockets were filled with either FDBA or PRF (prepared using 10cc of the patient’s blood). Bone regeneration was assessed by evaluating changes in horizontal and vertical bone dimensions after 12 weeks (the time of implant placement) using an acrylic stent fabricated before tooth extraction and a periodontal probe. The results were compared by repeated-measures analysis of variance (ANOVA; P<0.05).
    Results: Ridge width showed a significant reduction compared to the baseline in both groups (P=0.001); ridge height changes were not significant (P>0.05). The evaluated groups did not show any significant difference in height/width changes (P>0.05).
    Conclusion: The results showed an acceptable efficacy for PRF without graft materials in alveolar ridge preservation. This material is cost-effective and could be easily prepared. PRF application in extraction sockets yielded similar results to FDBA.

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    Objectives: Temporomandibular disorders (TMD) are characterized by pain or discomfort in the temporomandibular joint, periauricular region, masticatory muscles, and neck on one or both sides. It may also be associated with joint sounds, restricted mandibular movements and mandibular deviation. Oxidative agents may have a deleterious role in the pathogenesis of joint diseases, and oxidative stress can lead to TMD. The aim of this study was to assess the oxidative stress biomarkers in the saliva of TMD patients and healthy controls.
    Materials and Methods: This case-control study was conducted on 30 patients with TMDs (5 males and 25 females) with a mean age of 30.7±13.2 years, and 30 healthy controls (5 males and 25 females) with a mean age of 29.16±11.2 years. Saliva samples were collected according to the standard protocol and the total antioxidant capacity of the saliva (non-enzymatic), catalase activity, and malondialdehyde (MDA) levels were measured using the ferric reducing ability of plasma, Aebi’s method, and high-performance liquid chromatography, respectively. Finally, The MDA levels were analyzed by the Mann-Whitney test. Other quantitative parameters were analyzed by independent t-test.
     Results: TMD patients had significantly higher salivary levels of MDA compared to the control group (P=0.001). But there were no significant differences in catalase (P=0.49) and total antioxidant capacity (P=0.22) of TMD patients and healthy controls.
    Conclusion: It seems that oxidative stress may be involved in the pathogenesis of TMDs.

Case Report

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    Dental traumatic injuries most commonly occur in the primary and mixed dentition, but vertical complicated crown-root fractures are rarely seen in children. Clinical and radiographic examination of these injuries helps in accurate diagnosis and management. According to the International Association of Dental Traumatology guidelines, treatment usually involves extraction followed by placement of a space maintainer. Cases of complicated crown and root fracture in primary posterior teeth are often unnoticed by the clinician, at the time of injury. Two such patients are presented, who reported symptoms a few weeks after their accident. They were managed conservatively by initial stabilization with stainless steel crowns, followed by root canal therapy. This report highlights the need for referral to specialists and emphasizes the importance of conservative management of primary teeth to maintain functional demands.

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    Extraoral sinus tracts of odontogenic origin often develop as the result of misdiagnosis of persistent dental infections due to trauma, caries, or periodontal disease. Due to these lesions' imitation from cutaneous lesions, misdiagnosis, and mismanagement, which we frequently encounter, this article aims to describe four cases with manifestations in different parts of the face and the neck. Patients were referred to an endodontist with a history of several surgical procedures and/or antibiotic therapy due to misdiagnosis. After comprehensive examinations, root canal treatment was performed. The resolution of signs and symptoms during the follow-up period confirmed the correct diagnosis. Dermatologists and other physicians should be aware of the possibility of the relationship of extraoral sinus tracts with dental infections. Precise examination and taking a comprehensive history can aid to prevent unnecessary and incorrect therapeutic and/or pharmaceutical interventions. Elimination of dental infection leads to complete recovery in such patients.

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    Endodontic treatment of maxillary incisors may be considered straight forward. However, in some instances, they may exhibit aberrant morphology. One of these rare variations in tooth morphology is dens invaginatus. To improve the endodontic prognosis of such teeth, a detailed evaluation of the tooth under treatment is important, which requires comprehensive clinical and radiographic examinations, including periapical radiography and cone-beam computed tomography (CBCT), which is highly recommended whenever atypical root canal morphology is suspected on a periapical radiograph. The current case report discusses the diagnosis of type IV dens invaginatus in a maxillary lateral incisor using CBCT.

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    Implant insertion into an atrophic knife-edge ridge with non-simultaneous extraction of anterior and posterior teeth is challenging; this is why bone regeneration before implant placement is of great importance. One of the best sources for reconstruction is an intraoral autogenous bone graft. A composite bone graft is a combination of autogenic bone and mucosal flap that provides adequate blood supply and fixation compared to conventional (from the mandibular symphysis or ramus) and extraoral bone grafts.

Short Communication

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    The coronavirus disease 2019 (COVID-19) turned into a pandemic in short-time with multi-dimensional effects on human lives. The containment of this infection has become a big challenge in all countries due to its rapid spread. In this situation, when there is no definitive cure or any vaccine available to overcome COVID-19, it is prudent for the world to live with this deadly virus for the many months to come. Hence, it is imperative for the dental professionals, particularly orthodontists, to modify their approach to learn the new normal of practicing dentistry.