Efficacy of a smartphone application as an aid to enhance the instruction of radiographic differential diagnosis of maxillofacial bony lesions.

OBJECTIVES: The purpose of this study was to assess the efficacy of a smartphone application for instruction of radiographic differential diagnosis of maxillofacial bony lesions as an aid to enhance to traditional learning (lecture-based learning) for dental students. METHODS: This quasi-experimental study evaluated 50 fifth-year dental students who were randomly divided into two groups. The two groups were matched in terms of grade point average to ensure their equal baseline knowledge level. The experimental group (n = 25) received instructions regarding differential diagnosis of maxillofacial bony lesions via a self-designed smartphone application, while the control group (n = 25) received lecture-based instruction of the same topic. The students participated in a written exam (10 questions) immediately and 2 months after the interventions. Each question had 3 differential diagnosis choices. The best answer choice was allocated a score of 0.5, while other answer choices were allocated a score of 0.25. Data were analyzed using repeated measures ANOVA, and Mann-Whitney U and Wilcoxon tests. RESULTS: The mean score of the experimental group was significantly higher than that of the control group immediately after the intervention (p < 0.001) and also at 2 months (p < 0.001). The mixed effect linear model revealed that after controlling for the effect of age and sex, the mean score of the experimental group was still significantly higher than that of the control group immediately and at 2 months after the intervention (p < 0.001). CONCLUSIONS: Smartphone-based mobile learning can effectively enhance the knowledge and practical skills of dental students in differential diagnosis of maxillofacial bony lesions as an aid to enhance to traditional learning.

The Most Common Vitamin D Receptor Polymorphisms (ApaI,FokI, TaqI, BsmI, and BglI) in Children with Dental Caries: A Systematic Review and Meta-Analysis.

Vitamin D participates in the calcification of enamel and dentin and the appropriate immune responses to oral microbial infections. We aimed to assess the association between the most common vitamin D receptor (VDR) polymorphisms (ApaI,FokI, TaqI, BsmI, and BglI) and the risk of dental caries in children. METHODS: PubMed/MEDLINE, Cochrane Library, Web of Science, and Scopus databases were comprehensively searched until 19 January 2021. Meta-analysis with odds ratios as the effect estimate along with 95% confidence intervals and subgroup analysis were conducted using Review Manager 5.3 software. Publication bias and sensitivity analyses were conducted by Comprehensive Meta-Analysis, version 2.0 software. RESULTS: Seventy-eight studies were retrieved from the databases, with nine studies included in the final analysis. Based on five genetic models, there was no association between ApaI (rs7975232), TaqI (rs731236), BsmI (rs1544410), FokI (rs2228570), and BglI (rs739837) polymorphisms and susceptibility to dental caries, except for the FokI (rs10735810) polymorphism. CONCLUSION: Among the VDR polymorphisms considered, an association was found between the FokI (rs10735810) polymorphism and the risk of dental caries, with a protective role of the f allele and ff genotype.

Association between IL-8 (-251T/A) and IL-6 (-174G/C) Polymorphisms and Oral Cancer Susceptibility: A Systematic Review and Meta-Analysis.

BACKGROUND AND OBJECTIVE: Inflammation and cell-mediated immunity can have significant roles in different stages of carcinogenesis. The present meta-analysis aimed to evaluate the association between the polymorphisms of IL-8 (-251T/A) and IL-6 (-174G/C) and the risk of oral cancer (OC). METHODS: PubMed/MEDLINE, Web of Science, Cochrane Library, and Scopus databases were searched until December 18, 2020 without any restrictions. RevMan 5.3 software was used to calculate the results of forest plots (odds ratios (ORs) and 95% confidence intervals (CIs)); CMA 2.0 software was used to calculate funnel plots (Begg's and Egger's tests), and SPSS 22.0 was used for the meta-regression analysis. Moreover, trial sequential analysis was conducted to estimate the robustness of the results. RESULTS: Eleven articles including twelve studies were selected for the meta-analysis. The pooled ORs for the association between IL-8 (-251T/A) polymorphism and the risk of OC in the models of A vs. T, AA vs. TT, TA vs. TT, AA + TA vs. TT, and AA vs. TT + TA were 0.97 (p = 0.78), 0.86 (p = 0.55), 0.78 (p = 0.37), 0.83 (p = 0.45), and 1.10 (p = 0.34), respectively. The pooled ORs IL-6 (-174G/C) polymorphism and the risk of OC in the models of C vs. G, CC vs. GG, GC vs. GG, CC + GC vs. GG, and CC vs. GG + GC were 1.07 (p = 0.87), 1.17 (p = 0.82), 1.44 (p = 0.38), 1.28 (p = 0.61), and 0.96 (p = 0.93), respectively. There was no association between IL-8 (-251T/A) polymorphism and OC susceptibility, but the C allele and GC and CC genotypes of IL-6 (-174G/C) polymorphism were associated with the risk of OC based on subgroup analyses, that is to say, the source of control and the genotyping method might bias the pattern of association. CONCLUSIONS: The meta-analysis confirmed that there was no association between the polymorphisms of IL-6 (-174G/C) and IL-8 (-251T/A) and the susceptibility of OC. However, the source of control and the genotyping method could unfavorably impact on the association between the polymorphisms of IL-6 (-174G/C) and the risk OC.

Simulated Evaluation of Tooth Fracture Resistance during Instrumentation with Single-and Multi-file Rotary Systems.

Introduction: Use of rotary files in root canal preparation is inevitable due to their high speed and reduced duration of treatment. However, microcracks and even root fracture may sometimes occur in teeth where canal(s) is/are prepared using these devices. The purpose of the current study was to compare NeoNiti single-file with RaCe multi-file rotary systems. Materials and Methods: An accurate scanner designed detailed three-dimensional file models, and a simulated model was developed using canal-specific features; including dentin thickness, root canal length, taper rate and root canal curvature. Cleaning and shaping conditions were simulated with appropriate speed and crack conditions for both types of files on the computer. Strain accumulation sites in the root dentin wall where microcracks was likely to occur were simulated and investigated. Abaqus and ANSYS software were used to perform finite element simulations. Results: RaCe files with 0.04 taper caused the lowest level of stress (34.33 MPa) to the simulated canal. Conversely, the highest level of stress (62.35 MPa) was applied by 8% NeoNiti file to the simulated canal. Conclusions: Based on the present experimental study, it can be concluded that RaCe multi-file rotary system may better be used in endodontic therapy, and the risk of microcracks in the tooth wall is less than that of NeoNiti single-file rotary system.

Effectiveness of Two Types of Photostimulable Phosphor Plate Plastic Barrier Envelopes for Prevention of Microbiological Contamination

Abstract Objective: To compare the effectiveness of two types of commercially available photostimulable phosphor plate (PSP) protective barrier envelopes to prevent microbiological contamination. Material and Methods: In this cross-sectional study, 80 barrier envelopes were tested in 40 volunteers. The PSP plates were placed individually in Asia Teb and Soredex protective barrier envelopes and were placed in the mouth for two minutes, similar to periapical films. The protective barrier envelopes were then removed under sterile conditions, and the sensors were placed on different culture media. The number of colonies on each plate was counted. Data were analyzed using SPSS via McNemar and Wilcoxon tests. Results: Bacterial growth was noted in 17.5% of PSPs with Soredex, and 32.5% of PSPs with Asia Teb barrier envelopes. Gram-positive bacilli were the most commonly isolated bacteria. The difference between the Asia Teb and Soredex barrier envelopes for the protection of microbiological contamination was not significant (p>0.05). Conclusion: The use of different types of protective barrier envelopes was not sufficient for prevention of microbiological contamination of PSP plates, and some adjunct modalities were required to decrease microbiological contamination of PSP plates.

Patterns of Mandibular Third Molar Impaction in an Iranian Subpopulation

Abstract Objective: To assess the patterns of mandibular third molar impaction in an Iranian subpopulation. Material and Methods: This retrospective descriptive study evaluated 1000 panoramic radiographs retrieved from the archives of a private radiology clinic in Kermanshah city, Iran. Depth of impaction, position of impacted mandibular third molar relative to the mandibular ramus according to Pell and Gregory's classification and angle of impacted tooth according to Winter's classification were determined. Data were analyzed using the Chi-square and Wilcoxon tests. Results: Of 1000 radiographs, 230 (23%) showed an impaction of at least one mandibular third molar. Mandibular third molar impaction was more common in females (60%). Mesioangular (35.9%) and vertical (34.8%) impactions were the most common angles of impaction in the right and left sides, respectively. Level C (40.3%) and Class I (63.7%) were the most common types of impaction in terms of depth of impaction and position relative to ramus, respectively. No significant difference was observed between the right and left sides of the mandible in terms of patterns of mandibular third molar impaction (p>0.05). Conclusion: Mandibular third molar impaction was relatively common in the studied population. The mesioangular, level C and Class I impaction patterns were the most frequent.

Effect of Experience in Landmark Identification on 2D Lateral Cephalograms on Performance of Dental Students Concerning Landmark Identification on 3D Cone Beam Computed Tomography Scans

Abstract Objective: To assess the effect of experience in landmark identification on two-dimensional (2D) lateral cephalograms on performance of dental students concerning landmark identification on three-dimensional (3D) cone-beam computed tomography (CBCT) scans. Material and Methods: This quasi-experimental study evaluated 40 dental students in two groups (n=20). Group 1 included senior dental students who had experience in landmark identification on 2D lateral cephalograms and Group 2 included third-year dental students with no such experience. Both groups received instructions on identification of eight landmarks on 3D CBCT scans. The coordinates of the landmarks were determined in x, y and z axes. One orthodontist determined the mean coordinates of each landmark as a reference by twice measurements with a one-week interval. The mean distance from the identified points to the reference points was reported as the mean consistency (MC), and the standard deviation of the mean was considered as precision of landmark identification. Data were analyzed using independent samples t-test. Results: The mean distances from the points identified as nasion, point B, orbitale, anterior nasal spine (ANS), menton, coronoid process and pogonion in x, y and z axes and point A in x and z axes (p<0.001) to the reference points in Group 1 were greater than those in Group 2 with no such experience. Conclusion: Previous experience in landmark identification on 2D cephalograms does not help in landmark identification on 3D CBCT scans and may even adversely affect the results.

Effect of exposure parameters of cone beam computed tomography on metal artifact reduction around the dental implants in various bone densities.

BACKGROUND: This study aimed to assess the effect of exposure parameters such as milliampere (mA) and field of view (FOV) of cone beam computed tomography (CBCT) on a metal artifact of dental implants placed in different bone densities. METHODS: A total of 27 bone blocks with different densities (nine were type 1, nine were types 2 and 3, and nine were type 4) were used in this in vitro, experimental study. These blocks were placed in mandibular wax models. The blocks were scanned after drilling (hole preparation) and after implant placement using Cranex3D imaging system with a 4 × 6 cm2and 6 × 8 cm2 FOV and 4 and 10 mA. Gray value of the bone blocks was recorded before and after placement of implants. RESULTS: In general, irrespective of bone density, the amount of artifacts was lower in small FOV compared to large FOV (P < 0.05). Change of mA had no effect on metal artifacts (P > 0.05). Artifacts in type 4 bone were greater than in other bone types (P < 0.05). Difference between type 1 and types 2 and 3 was not significant (P > 0.05). CONCLUSION: According to the results of this study, Peri-implant artifacts were seen in all bone types; the amount of artifacts in type 4 bone was higher than that in other types. Size of FOV and bone density affect the metal artifacts around dental implants; so that a smaller FOV can be used to decrease metal artifacts.

In vitro evaluation of coronal discoloration following the application of calcium-enriched mixture cement, Biodentine, and mineral trioxide aggregate in endodontically treated teeth.

BACKGROUND: This study sought to assess and compare coronal discoloration following the application of white mineral trioxide aggregate, Biodentine, and calcium-enriched mixture cement in endodontically treated teeth. MATERIALS AND METHODS: In this in vitro experimental study, 64 freshly extracted sound human premolars were selected, cleaned, and stored in saline. After cleaning, shaping, and obturation the root canal of the teeth, the teeth were randomly assigned to one control (n = 4) and three experimental (n = 20) groups. In the experimental groups, the cement were applied over the canal orifices in 3-mm thickness. All teeth were then restored with composite resin. Color parameters, according to the CIE L*a*b* system, were measured using Vita Easyshade spectrophotometer before application of cement and at 1 week, 1 month, 2 months, and 3 months after the application of cement. The recorded values were statistically analyzed using descriptive and analytical statistics. For analytical statistics, Kolmogorov-Smirnov test was applied to assess normal distribution of data. ANOVA was used to compare the results at baseline and repeated measures. P < 0.05 was considered statistically significant. RESULTS: Significant differences were noted in color change (ΔE) between all time points except between ΔE4 (2 months) and ΔE5 (3 months) (P < 0.01). However, tooth discoloration caused by the three cement was not significantly different (P = 0.343). CONCLUSION: The three tested cement were not significantly different in terms of causing coronal discoloration in endodontically treated teeth.

The comparison of the rate of apical displacement in curved root canals using Neoniti and RaCe files by cone beam CT Scan / Comparação da taxa de desvio apical em canais radiculares curvos utilizando limas Neoniti e RaCe por meio de tomografia computadorizada cone beam (TCCB)

Objective: There is a high prevalence of root canal transportation in the teeth with the curve. Effect of root canal transportation on the success of root canal therapy of tooth is negative and there is no study about comparing RaCe and Neoniti files in root canal transportation. The aim of this study is assessment and comparing two different RaCe and Neoniti files to determine transportation error in various parts of root using CBCT assessment and comparing them with each other. Material and Methods: In this experimental study 50 extracted mandibular molar teeth selected. Teeth were divided randomly into two groups i.e. 25 teeth threated with RaCe file (first group) and 25 teeth threated with Neonitu files (second group). CBCT images were used to measurement thickness of dentine, before and after instrumentation that obtain from NNT viewer 6.1.0 software. Results: In the first group, the mean tooth transportation in 5 mm of apex was 0.15 and, in the second group, the mean tooth transportation in 5 mm of apex was 0.18 mm. There was no statistically significant difference in canal transportation between RaCe and Neoniti files in five millimeters distant from apex area (p = 0.492) and the mean transportation from 9 mm of apex were 0.14 in the second group. There was no statistically significant difference in canal transportation between two groups (p = 0.911). Conclusion: In comparison of these two rotary files, both are equally safe regarding the extent of apical transportation. (AU)

Objetivo: Existe uma alta prevalência de desvio apical em canais radiculares curvos. O efeito do desvio apical no canal radicular sobre o sucesso da terapia endodôntica é desfvorável e não há nenhum estudo comparando as limas RaCe e Neoniti em relação ao desvio apical dos canais radiculares durante o preparo. O objetivo deste estudo é avaliar e comparar duas diferentes limas, RaCe e Neoniti, a fim de para determinar o erro de desvio em várias porções radiculares através de análise por TCCB e compará-los entre eles. Material e Métodos: Neste estudo experimental, 50 dentes molares mandibulares extraídos foram selecionados. Os dentes foram divididos aleatoriamente em dois grupos, ou seja, 25 dentes preparados com as limas RaCe (primeiro grupo) e 25 dentes preparados com limas Neoniti (segundo grupo). Neste estudo para medir a espessura da dentina através do escaneamento, antes e depois da instrumentação, ao mesmo tempo, usamos imagens axiais obtidas do software NNT viewer 6.1.0. Resultados: No primeiro grupo, o desvio apical médio a 5 mm do ápice foi de 0,15 e no segundo grupo o desvio apical médio a 5 mm do ápice foi de 0,18 mm, não havendo diferença estatisticamente significante entre as limas RaCe e Neoniti a cinco milímetros da porção apical (p = 0,492) e o transporte médio a 9 mm do ápice foi de 0,14 no segundo grupo não havendo diferença estatisticamente significante no desvio apical entre os dois grupos (p = 0,911). Conclusão: Os resultados indicaram que não houve diferença significativa no desvio apical médio entre dois sistemas de limas em 3, 9, 7, 5 e 11 mm do ápice e ambos as limas foram seguras (AU)

Performance of Cone Beam Computed Tomography Systems in Visualizing the Cortical Plate in 3D Image Reconstruction: An In Vitro Study.

INTRODUCTION: Cortical bone is an important anatomical structure and its thickness needs to be determined prior to many dental procedures to ensure treatment success. Imaging modalities are necessarily used in dentistry for treatment planning and dental procedures. Three-dimensional image reconstruction not only provides visual information but also enables accurate measurement of anatomical structures; thus, it is necessarily required for maxillofacial examination and in case of skeletal problems in this region. AIMS: This study aimed to assess the ability of three Cone Beam Computed Tomography (CBCT) systems including Cranex 3D, NewTom 3G and 3D Promax for Three-Dimensional (3D) image reconstruction of the cortical plate with variable thicknesses. METHODS: Depending on the cortical bone thickness, samples were evaluated in three groups of ≤ 0. 5 mm, 0.6 -1 mm and 1.1-1.5 mm cortical bone thickness. The CBCT scans were obtained from each sample using three systems, their respective FOVs, and 3D scans were reconstructed using their software programs. Two observers viewed the images twice with a two-week interval. The ability of each system in the 3D reconstruction of different thicknesses of cortical bone was determined based on its visualization on the scans. The data were analyzed using SPSS and Kappa test. RESULTS: The three systems showed the greatest difference in the 3D reconstruction of cortical bone with < 0.5 mm thickness. Cranex 3D with 4×6 cm2 FOV had the highest and 3D Promax with 8×8 cm2 FOV had the lowest efficacy for 3D reconstruction of cortical bone. Cranex 3D with 4×6 cm2 and 6×8 cm2 FOVs and NewTom 3G with 5×5 cm2 and 8×5 cm2 FOVs showed significantly higher efficacy for 3D reconstruction of cortical bone with 0.6-1mm thickness while 3D Promax followed by NewTom 3G with 8×8 cm2 FOV had the lowest efficacy for this purpose. CONCLUSION: Most CBCT systems have high efficacy for 3D image reconstruction of cortical bone with thicknesses over 1 mm while they have poor efficacy for image reconstruction of cortical bone with less than 0.5 mm thickness. Thus, for accurate visualization of anatomical structures on CBCT scans, systems with smaller FOVs and consequently smaller voxel size are preferred.

Apical Microleakage in Root Canals Containing Broken Rotary Instruments.

INTRODUCTION: Broken instruments in root canals complicate routine endodontic treatment. This study aimed to compare apical microleakage in root canals containing broken rotary instruments filled with mineral trioxide aggregate (MTA), calcium-enriched mixture (CEM) cement, laterally compacted gutta-percha and injected gutta-percha. METHODS AND MATERIALS: In this in vitro, experimental study, 80 extracted human premolars were decoronated and then the roots were randomly divided into four groups (n=20). Root canals were instrumented with Mtwo rotary files. The files were scratched 3 mm from the tip by a high speed handpiece and they were intentionally broken in the apical third of the canals. The middle and coronal thirds of the canals were then filled with MTA, CEM cement, gutta-percha with lateral compaction technique and injected gutta-percha. Apical microleakage was measured using dye penetration method. Data were analyzed using ANOVA and Tukey's test. RESULTS: Root canals filled with CEM cement showed the lowest and those filled with injected gutta-percha showed the highest microleakage according to dye penetration depth. No significant difference was noted between the microleakage of CEM cement and MTA or between lateral compaction of gutta-percha and injected gutta-percha (P>0.05). However, CEM cement and MTA groups had significantly lower microleakage than laterally compacted and injected gutta-percha groups (P<0.05). CONCLUSION: Due to their superior sealing ability, MTA and CEM cement are suitable for filling of root canals containing a broken instrument compared to laterally compacted and injected gutta-percha.

Cherubism: An Unusual Study With Long-Term Follow-Up.

Cherubism is an uncommon hereditary benign fibro-osseous disorder characterized by bilateral enlargement of the mandible and the maxilla that presents with varying degrees of involvement and a tendency toward spontaneous remission.The first visit was in 2002. A 16-year-old female was referred to an orthodontist for correction of her dental crowding. In the radiographic examination that was taken for her treatment the first time in 2002, a jaw bone lesion was discovered accidentally. X-ray panoramic imaging revealed well-defined multilocular radiolucencies involving the posterior body of the mandible and ascending rami with displaced teeth. This lesion had no effect on inferior alveolar canal and maxilla.There was no significant past medical history, and there was no family history suggestive of a similar complaint. On extraoral examination, there was no swelling in both rami of the mandible and face. Histopathological examination of the biopsy specimen showed proliferating fibrous connective tissue interspersed by multinucleated giant cells. It was diagnosed as a case nonfamilial cherubism. An extensive long-term follow-up till 12 years was maintained. In 2014, after 12-years follow-up for this lesion, panoramic imaging examination showed progress of this lesion in mandible and maxilla.

Influence of Head Orientation in Linear Measurement for Implant Planning in Cone Beam Computed Tomography.

AIM: Use of dental implants in edentulous patients has become a common treatment modality. Treatment of such implants requires radiographic evaluation, and in most cases several different imaging techniques are necessary in order to evaluate the height, width and the structure of bone at implant site. The aim of this study was to evaluate the influence of head orientation in linear measurement for implant planning in cone beam computed tomography (CBCT). MATERIALS AND METHODS: In the present in vitro study, 11 human dry mandibles were used. The width and height of bone at the central, canine and molar teeth areas were measured on the left and right sides by using digital calipers (as gold standard) and on CBCT images with Reaxis option and no Reaxis. Data were analyzed with Statistical package for the social sciences (SPSS) 18, using pair t-test, Tukey test and intraclass correlation (ICC). RESULTS: Data were collected by evaluation of 11 skulls and 66 samples on the whole. There were no significant differences in bone width in any area in both Reaxis and no Reaxis option (p > 0.05). There were significant differences in bone height in the central (p = 0.005) and molar teeth areas (p = 0.010). The results did not show any significant differences between the observers (p = 0.329). CONCLUSION: Using the Reaxis option does not affect the measurement of bone width, while use of this option can make a significant difference for height measurements.

Evaluation of the accuracy of linear measurements on lateral cephalograms obtained from cone-beam computed tomography scans with digital lateral cephalometric radiography: an in vitro study.

OBJECTIVES: A cephalometric analysis especially designed for the patient who requires maxillofacial surgery was developed to use landmarks and measurements that can be altered by common surgical procedures. Identification of landmarks in cephalometry is very important and useful for orthognathic surgery. The aim of this study was to evaluate the accuracy of linear measurement based on digital lateral cephalograms (DLC) and on lateral cephalograms obtained from cone-beam computed tomography (CBCT) scans. MATERIALS AND METHODS: The linear distances between anatomic landmarks on 6 dry human skulls were measured by 2 observers using digital calipers for sella-nasion (S-N), menton-nasion (M-N), anterior nasal spine-nasion (ANS-N), anterior nasal spine-posterior nasal spine (ANS-PNS), and pogonion-gonion (Pog-Go). Then, images were obtained by using DLCs and in lateral cephalograms obtained from CBCT scans. The measurement errors were calculated for each modality, compared with each other, and analyzed via SPSS software version 18. RESULTS: For all lines (S-N, M-N, ANS-N, Pog-Go, and ANS-PNS), CBCT-derived values did not differ from actual dry skull dimensions (gold standard) (P > 0.05). In DLC, for S-N, M-N, ANS-N, and Pog-Go lines, measurements were significantly higher than actual measurements (P ≤ 0.05), but ANS-PNS values did not differ from actual measurements (P > 0.05). CONCLUSIONS: The results showed that the values obtained in CBCT imaging compared with calculated values of the digital lateral cephalometry much closer to the actual distance are more accurate indicators of this type of imaging and that CBCT permits oral surgeons to visualize the position and surgical anatomy of the tooth as it will be seen in the operating theater and allows orthodontists to plan directional traction.

Assessment of dental implant site dimensions in cone beam computed tomography systems / Avaliação das dimensões da área de implante dentário com sistemas de tomografia computadorizada de feixe cônico

Objective: The aim was to investigate the accuracy of linear measurements of the mandibular ridge recorded using two CBCT systems. Material and Methods: Eleven human dry skull were used in which mandibles were chosen to measure width and height in 6 sites. Before scanning, the points were marked using barium sulfate radiopaque contrast media. Mandible imaging was done using two systems: Newtom3G and Cranex3D. Alveolar ridge dimensions were recorded by two observers under uniform condition using special software for each system. The measurement errors and inter-examiner reliability were calculated for each modality and compared with each other and analyzed via SPSS software version 18. The level of significance was set at P < 0.05. Results: The overall mean was 0.08 mm for Cranex system and 0.5 for Newtom system. The mean of two systems had no statistically significant difference in comparison with each other or with the gold standard. The statistical analysis showed high inter-observer reliability (P < 0.05). Conclusion: CBCT is highly accurate and reproducible in linear measurements in the different areas of the maxillofacial region.

Objetivo: O objetivo deste estudo foi investigar a acurácia de medidas lineares do rebordo mandibular utilizando dois sistemas de TCFC. Material e Métodos: Onze crânios secos humanos foram utilizadas e seis regiões das mandíbulas foram escolhidos para mensuração da largura e da altura. Antes da digitalização, os pontos foram marcados com contraste radiopaco de sulfato de bário. Imagens da mandíbula foram realizadas usando dois sistemas: Newtom3G e Cranex3D . As dimensões rebordo alveolar foram determinadas por dois observadores em condições uniformes utilizando software específico para cada sistema. Os erros de medição e confiabilidade interexaminadores foram calculados para cada modalidade, utilizando o software SPSS versão 18, e comparados entre si. O nível de significância adotado foi p < 0,05. Resultados: A média geral para o sistema Cranexfoi de 0,08 mm e 0,5 para o sistema de Newton. As médias dos dois sistemas não apresentaram diferença estatisticamente significativa em comparação entre si ou com o padrão-ouro. A análise estatística mostrou alta confiabilidade interexaminador (p < 0,05). Conclusão: TCFC é altamente precisa e reprodutível em medidas lineares nas diferentes áreas da região maxilofacial.

Evaluation of the quality of four root canal obturation techniques using micro-computed tomography.

INTRODUCTION: One of the key factors in successful endodontic therapy is to adequately fill the root canals. The aim of this in vitro study was to compare the quality of four different root canal obturation techniques: cold lateral condensation (CLC), warm vertical condensation (WVC), Obtura II (OII) and Gutta Flow (GF) by using micro-computed tomography (micro CT). MATERIALS AND METHODS: A total of 20 extracted maxillary first molars prepared with ProTaper files, were randomly divided into four groups. Micro CT was used to measure the internal volume of root canals. Following application of AH26 sealer to canal obturation, new micro-CT images were taken and the volume percentage (VP) of voids, gutta-percha and sealer at different levels were calculated with CT software. Data was statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests. RESULTS: The highest percentage of filling material was observed in GF group followed by OII with no statistically significant difference (P>0.05). These two groups had a significantly more acceptable filling than WVC and CLC groups (P<0.05). Voids were detected in all samples. There was a significant difference between the highest and the lowest percentage of voids in CLC (19.6%) and GF groups (6.7%), respectively. In the apical third, CLC and OII showed the highest and the lowest percentage of voids (5.5% and 2.6%) and the lowest and highest percentage of gutta-percha (76.52% and 94.26%), respectively. These differences were statistically significant (P<0.05). CONCLUSION: None of the root canal filled teeth were gap-free. GF and CLC techniques showed the highest and lowest VP of obturation materials, respectively.

Prevalence of C-shaped root canals in Iranian population: a systematic review.

OBJECTIVE: Because of the great challenges in the diagnosis and treatment of "C" configuration and lack of any systematic information about its occurrence, the purpose of the present study is to determine the prevalence of C shaped root canals in Iranian population. METHODOLOGY: An exhaustive search was undertaken to identify published and unpublished researches related to the C-shaped canals by using key words. The search of the MEDLINE database included all publications from 1966 to May 2012.Then selected articles were obtained and reviewed. Data evaluated and summarized in the data sheet included methodology, population, number of teeth per study (power), number of root canals, type of root canal configuration, and c-shaped canals. RESULTS: Six studies were included with total of 1062 teeth, all in mandibular second molars. The total incidence of C-shaped canals in Iranian population was obtained 6.96%. CONCLUSIONS: The incidence of C-shaped canals in Iranian population is 6.96%, which seems much less than Asian populations but nearer to Middle East countries.