Ultrasonic mapping of midpalatal suture - An ex-vivo study.

OBJECTIVE: Rapid maxillary expansion is a common orthodontic procedure to correct maxillary constriction. Assessing the midpalatal suture (MPS) expansion plays a crucial role in treatment planning to determine its effectiveness. The objectives of this preliminary investigation are to demonstrate a proof of concept that the palatal bone underlying the rugae can be clearly imaged by ultrasound (US) and the reconstructed axial view of the US image accurately maps the MPS patency. METHODS: An ex-vivo US scanning was conducted on the upper jawbones of two piglet's carcasses before and after the creation of bone defects, which simulated the suture opening. The planar images were processed to enhance bone intensity distribution before being orderly stacked to fuse into a volume. Graph-cut segmentation was applied to delineate the palatal bone to generate a bone volume. The accuracy of the reconstructed bone volume and the suture opening was validated by the micro-computed tomography (µCT) data used as the ground truth and compared with cone beam computed tomography (CBCT) data as the clinical standard. Also included in the comparison is the rugae thickness. Correlation and Bland-Altman plots were used to test the agreement between the two methods: US versus µCT/CBCT. RESULTS: The reconstruction of the US palatal bone volumes was accurate based on surface topography comparison with a mean error of 0.19 mm for pre-defect and 0.15 mm and 0.09 mm for post-defect models of the two samples, respectively when compared with µCT volumes. A strong correlation (R2 ≥ 0.99) in measuring MPS expansion was found between US and µCT/CBCT with MADs of less than 0.05 mm, 0.11 mm and 0.23 mm for US, µCT and CBCT, respectively. CONCLUSIONS: It was possible to axially image the MPS opening and rugae thickness accurately using high-frequency ultrasound. CLINICAL SIGNIFICANCE: This study introduces an ionizing radiation-free, low-cost, and portable technique to accurately image a difficult part of oral cavity anatomy. The advantages of conceivable visualization could promise a successful clinical examination of MPS to support the predictable treatment outcome of maxillary transverse deficiency.

An evaluation of root resorption associated with the use of photobiomodulation during orthodontic treatment with clear aligners: a retrospective cohort pilot study.

OBJECTIVES: To evaluate the change in tooth root volume using cone-beam computed tomography (CBCT) in a group of patients treated concurrently with clear aligners and an adjunctive photobiomodulation (PBM) device. MATERIALS AND METHODS: This retrospective cohort pilot study included the records of 32 consecutively treated clear aligner patients (23 female, 9 male) from the private practice of one orthodontist. The PBM group (n = 16) used the device once per day for 5 minutes per arch and was compared with a matched control group (n = 16). A semiautomated segmentation technique was used to obtain tooth volume of anterior teeth from CBCT imaging prior to (T0) and during or immediately following (T1) orthodontic treatment with clear aligners. The change in root volume between time points was assessed. RESULTS: There was no statistically significant difference between the pre- and posttreatment root volumes of maxillary and mandibular anterior teeth, regardless of which intervention group the patient belonged to (P > .05). There was also no difference in the mean percentage change in root volume between clear aligner patients in this study who were treated with the PBM device compared with a matched control group (P > .05). CONCLUSIONS: Clear aligner patients in this study who changed their aligners every 3 to 5 days and used adjunctive photobiomodulation therapy did not experience clinically relevant orthodontically induced external root resorption. Due to the small sample size and measurement error in the root segmentation process, the results should be interpreted with caution.

Are multi-detector computed tomography and cone-beam computed tomography exams and software accurate to measure the upper airway? A systematic review.

BACKGROUND: Cone-beam computed tomography (CBCT) has several applications in various fields of dental medicine such as diagnosis and treatment planning. When compared to computed tomography (CT), CBCT's radiation exposure dose is decreased by 3%-20%. However, CBCT produces more scattered signals and may present poorer image quality when compared to medical CT. OBJECTIVES: To review the findings regarding the accuracy of multi-detector computed tomography (MDCT) and CBCT and to compare the different software programs that segment the upper airway. SEARCH METHODS: Three databases (PubMed, Medline, and Web of Science) were searched for articles and a manual search was performed. SELECTION CRITERIA: The inclusion criteria were defined following the PICO framework: P-any patient with a CBCT or CT; I-dimensional evaluation of the upper airway using MDCT or CBCT; C-phantoms; O-the primary outcome was MDCT and CBCT accuracy, the secondary outcome was the evaluation and comparison of software programs used to segment the upper airway. DATA COLLECTION AND ANALYSIS: Articles that met eligibility criteria were assessed using the Critical Appraisal Skills Program Checklist. RESULTS: Among the 16 eligible studies, 6 articles referred to the accuracy of MDCTs or CBCTs and 10 to the accuracy of the software. Most articles were qualified as high quality. CONCLUSIONS: MDCT and CBCT scans' accuracy in upper airway dimensional measurements depends on machine brand, parameters, and segmentation technique. Regarding the segmentation technique, 12 programs were studied. Most either underestimated or overestimated upper airway measurements. In particular, OnDemand3D and INVIVO showed poor accuracy. On the contrary, Invesalius, and MIMICS were accurate in assessing nasal cavities when using an interactive threshold. However, results varied due to methodological differences among the studies. Finally, fully automatic segmentation based on artificial intelligence may represent the future of airway segmentation because it is faster and seems to be accurate. However, further studies are necessary. REGISTRATION: This study was registered in Prospero (International Prospective Register of Systematic Reviews) with the ID number CRD42022373998.

Development and initial validation of a questionnaire to measure patient experience with oral appliance therapy.

STUDY OBJECTIVES: To develop and validate a questionnaire to measure patient experience with oral appliance therapy. METHODS: The AMEE Guide No. 87 was followed in the development and validation of a patient questionnaire to assess patient experience with oral appliance therapy. RESULTS: Our search identified 522 articles; 5 of these articles described the use and/or validation of questionnaires to measure changes in symptoms and patient-reported outcomes in the treatment of obstructive sleep apnea. A total of 27 questions were developed. Five patients participated in pilot testing. A final review of the questionnaire was conducted by an expert panel. CONCLUSIONS: The creation and validation of a questionnaire to assess patient experience with oral appliance therapy may provide new methods for advancing research in the field of dental sleep medicine. CITATION: Ng ET, Perez-Garcia A, Lagravère-Vich MO. Development and initial validation of a questionnaire to measure patient experience with oral appliance therapy. J Clin Sleep Med. 2023;19(8):1437-1445.

Comparison of screening methods for obstructive sleep apnea in the context of dental clinics: A systematic review.

OBJECTIVE: To review the available bibliographic data to identify the best screening methods to detect potential obstructive sleep apnea (OSA) patients during dental clinical practice. METHODS: Relevant studies published up to April 2020 were sourced from PubMed, Embase, MEDLINE, Cochrane, and LILACS databases. RESULTS: Thirty studies were selected. For adults, the screening methods available to the dentist included questionnaires, scales, indexes, pulse oximetry, and anatomical factors. A combination of questionnaires is potentially the most reliable method to detect OSA risk. For children, only information on questionnaires and anatomical factors was found; two questionnaires accurately identified potential OSA risk cases. Anatomical factors also displayed a significant relation with OSA for both populations. CONCLUSION: Dentists have a fundamental role in early detection of potential OSA cases since they can use the methods identified in this review to perform an initial screening of the population. ABBREVIATIONS: OSA: Obstructive sleep apnea; PSG: Polysomnography; HST: Home sleep study; BMI: Body mass index; PPV: Positive predictive value; NPV: Negative predictive value; AHI: Apnea hypopnea index; RDI: Respiratory disturbance index; ODI: Oxygen desaturation index; PSQ: Pediatric Sleep Questionnaire; SRBD: Sleep-related breathing disorder; CSHQ: Children's Sleep Habits Questionnaire; ESS: Epworth Sleepiness Scale; PSQI: Pittsburgh Sleep Quality Index.

Can gray values be converted to Hounsfield units? A systematic review.

OBJECTIVES: The purpose of this systematic review was to answer the focus question: "Could the gray values (GVs) from CBCT (cone beam computed tomography) be converted to Hounsfield units (HUs) in multidetector computed tomography (MDCT)?" METHODS: The included studies try to answer the research question according to the PICO strategy. Studies were gathered by searching several electronic databases and partial grey literature up to January 2021 without language or time restrictions. The methodological assessment of the studies was performed using The Oral Health Assessment Tool (OHAT) for in vitro studies and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) for in vivo studies. The Grading of Recommendations Assessment, Development and Evaluation (GRADE system) instrument was applied to assess the level of evidence across the studies. RESULTS: 2710 articles were obtained in Phase 1, and 623 citations remained after removing duplicates. Only three studies were included in this review using a two-phase selection process and after applying the eligibility criteria. All studies were methodologically acceptable, although in general terms with low risks of bias. There are some included studies with quite low and limited evidence estimations and recommendation forces; evidencing the need for clinical studies with diagnostic capacity to support its use. CONCLUSIONS: This systematic review demonstrated that the GVs from CBCT cannot be converted to HUs due to the lack of clinical studies with diagnostic capacity to support its use. However, it is evidenced that three conversion steps (equipment calibration, prediction equation models, and a standard formula (converting GVs to HUs)) are needed to obtain pseudo Hounsfield values instead of only obtaining them from a regression or directly from the software.

Diagnostic accuracy of lateral cephalograms and cone-beam computed tomography for the assessment of sella turcica bridging.

INTRODUCTION: The purpose of this research was to assess the diagnostic accuracy of sella turcica bridging on lateral cephalograms when compared with true sella turcica bridging determined via cone-beam computed tomography (CBCT). METHODS: A cross-sectional study was conducted using CBCT images from which lateral cephalograms were generated. The study included 185 subjects (118 females and 67 males; age range, 10-30 years; mean age, 16.63 ± 4.20 years). Sella turcica landmarks and related measurements were calculated for both diagnostic modalities and analyzed by 1 examiner. Subjects were classified into 1 of 3 outcome groups: no bridging, partial bridging, and complete bridging. Diagnostic accuracy was evaluated using sensitivity, specificity, positive and negative predictive values, and receiver operator characteristic curves. RESULTS: Ten patients were diagnosed as complete bridging on CBCT, whereas 31 patients were diagnosed as complete bridging on lateral cephalogram. Although the lateral cephalogram detected all subjects with complete bridging, it incorrectly classified 12% of subjects. The percent agreement between both diagnostic methods was 55.68%, with a kappa statistic of 0.22 on the right sella turcica and 0.20 on the left sella turcica, indicating fair but statistically significant agreement. The overall accuracy of lateral cephalograms as a diagnostic modality in discriminating between no bridging and partial bridging was good as determined with the area under the curve values of 0.86 and 0.85 for right and left sides, respectively. CONCLUSIONS: Although lateral cephalograms overestimate patients with complete bridging compared to CBCTs, they are a suitable screening modality for accurately suggesting complete sella turcica bridging and differentiating between patients with no bridging and partial bridging.

Evaluation of the suture ossification level according to age and sex in children, adolescents, and adults. A cross-sectional and observational 3D study.

OBJECTIVE: To determine the ossification level of the midpalatal suture (MPS) in children, adolescents and adults from a Peruvian sample; according to the method proposed by Angelieri et al. with cone-beam computed tomographies (CBCTs). MATERIAL AND METHODS: The sample consisted of 315 CBCTs of 168 females and 147 males. The total sample was divided into 3 groups according to age and sex: children (n=77), adolescents (n=113) and adults (n=125). The images were mainly assessed in the axial plane using the Real Scan 2.0 software. The different periods of ossification of the MPS at the level of the vertical half of the palate was defined according to the five stages of Angieleri method (from A to E). The Student t-Test, Chi-square test, Kruskal-Wallis test and Spearman's Rho test were applied. RESULTS: Chi2 test results showed that the stages of MPS ossification depended on the age of the patient by age ranges (P<0.005). Multiple comparison tests affirmed that male and female subjects in the children group had fewer ossification stages than the adolescent and adult groups (P<0.001). Meanwhile, there were no statistically significant differences between the two older age groups. Finally, there was a moderate positive correlation between the stages of ossification of the MPS and the age in the male group (Rho=0.511). CONCLUSIONS: The onset of MPS ossification was significantly related to subjects up to 12 years of age and more frequently in stages B and C in both sexes. There was no difference in MPS ossification in adolescents and adult subjects.

The three-dimensional stable mandibular landmarks in patients between the ages of 12.5 and 17.1 years.

BACKGROUND: With the aid of implants, Björk identified two-dimensional mandibular stable structures in cephalograms during facial growth. However, we do not know what the three-dimensional stable structures are with certainty. The purpose of this study was to identify the most stable mandibular landmarks in growing patients using three-dimensional images. METHODS: The sample was comprised of two cone-beam computed tomography (CBCT) scans taken about 4.6 years apart in 20 growing patients between the ages of 12.5 (T1) and 17.1 years (T2). After head orientation, landmarks were located on the chin (Pog), internal symphysis (Points C, D and E), and mandibular canals, which included the mental foramina (MF and MFA) and mandibular foramina (MdF). The linear distance change between Point C and these landmarks was measured on each CBCT to test stability through time. The reliability of the suggested stable landmarks was also evaluated. RESULTS: The total distance changes between Point C and points D, E, Pog, MF, and MFA were all less than 1.0 mm from T1 to T2. The reliability measures of these landmarks, which were measured by the Cronbach alpha, were above 0.94 in all three dimensions for each landmark. From T1 to T2, the distance changes from Point C to the right and left mandibular foramina were 3.39 ± 3.29 mm and 3.03 ± 2.83 mm, respectively. CONCLUSIONS: During a growth period that averaged 4.6 years, ranging from 11.2 to 19.8 years old, the structures that appeared relatively stable and could be used in mandibular regional superimpositions included Pog, landmarks on the inferior part of the internal symphysis, and the mental foramen. The centers of the mandibular foramina and the starting points of the mandibular canal underwent significant changes in the transverse and sagittal dimensions.

Measurement error and reliability of three available 3D superimposition methods in growing patients.

INTRODUCTION: Cone-Beam Computed Tomography (CBCT) images can be superimposed, allowing three-dimensional (3D) evaluation of craniofacial growth/treatment effects. Limitations of 3D superimposition techniques are related to imaging quality, software/hardware performance, reference areas chosen, and landmark points/volumes identification errors. The aims of this research are to determine/compare the intra-rater reliability generated by three 3D superimposition methods using CBCT images, and compare the changes observed in treated cases by these methods. METHODS: Thirty-six growing individuals (11-14 years old) were selected from patients that received orthodontic treatment. Before and after treatment (average 24 months apart) CBCTs were analyzed using three superimposition methods. The superimposed scans with the two voxel-based methods were used to construct surface models and quantify differences using SlicerCMF software, while distances in the landmark-derived method were calculated using Excel. 3D linear measurements of the models superimposed with each method were then compared. RESULTS: Repeated measurements with each method separately presented good to excellent intraclass correlation coefficient (ICC ≥ 0.825). ICC values were the lowest when comparing the landmark-based method and both voxel-based methods. Moderate to excellent agreement was observed when comparing the voxel-based methods against each other. The landmark-based method generated the highest measurement error. CONCLUSIONS: Findings indicate good to excellent intra-examiner reliability of the three 3D superimposition methods when assessed individually. However, when assessing reliability among the three methods, ICC demonstrated less powerful agreement. The measurements with two of the three methods (CMFreg/Slicer and Dolphin) showed similar mean differences; however, the accuracy of the results could not be determined.

Effects of clear aligner therapy for Class II malocclusion on upper airway morphology and daytime sleepiness in adults: A case series.

INTRODUCTION: To evaluate the effects of clear aligner therapy (CAT) on the upper airway dimensions and on daytime sleepiness in adults with dentoskeletal Class II malocclusion. METHODS: This study was conducted from August 2017 to February 2019. Inclusion criteria were healthy adults≥18years old, Angle Class II division 1 malocclusion, first-molar relationship of end-to-end or greater, overjet<10mm, and presenting for multi-arch comprehensive orthodontic treatment with aligners. Treatment mechanics included mandibular dentoalveolar advancement with Class II elastics without maxillary sequential distalization programmed into aligners. Post-treatment changes in dentoskeletal and upper airway dimensions were assessed using CBCT images. The treatment effect on daytime sleepiness was evaluated using an Epworth Sleepiness Scale (ESS). RESULTS: Eight subjects were included in this pilot study (mean age at treatment initiation=44.6years [SD=15.3]). The mean treatment duration was 12.2months (SD=3.4). No statistically significant treatment changes were observed in upper airway dimensions or dentoskeletal cephalometric analyses. Subjects with excessive daytime sleepiness at pre-treatment reported an improvement post-treatment, but no significant difference in the mean ESS score was found. CONCLUSION: Treatment of Class II division 1 malocclusion in adults by mandibular dentoalveolar advancement using CAT has no statistically significant effects on the airway and dentoskeletal measurements, or daytime sleepiness.

Reliability of different three-dimensional cephalometric landmarks in cone-beam computed tomography : A systematic review.

OBJECTIVES: Conventional two-dimensional (2D) cephalometric radiography is an integral part of orthodontic patient diagnosis and treatment planning. One must be mindful of its limitations as it indeed is a 2D representation of a vaster three-dimensional (3D) object. Issues with projection errors, landmark identification, and measurement inaccuracies impose significant limitations, which may now be overcome with the advent of cone-beam computed tomography (CBCT). A systematic review of the reliability of different 3D cephalometric landmarks in CBCT imaging was conducted. MATERIALS AND METHODS: Electronic database searches were administered until October 2017 using PubMed, MEDLINE via OvidSP, EBMR and EMBASE via OvidSP, Scopus, and Web of Science. Google Scholar was used as an adjunctive search tool. RESULTS: Thirteen articles considering CBCT scans of human subjects from preexisting data sets were selected and reviewed. Most of the studies had methodological limitations and were of moderate quality. Because of their heterogeneity, key data from each could not be combined and were reported qualitatively. Overall, in 3D, midsagittal plane landmarks demonstrated greater reliability compared with bilateral landmarks. A minimum number of dental landmarks were reported, although most were recommended for use. CONCLUSIONS: Further research is required to evaluate the reliability of 3D cephalometric landmarks when evaluating 3D craniofacial complexes.

Reliability of three-dimensional anterior cranial base superimposition methods for assessment of overall hard tissue changes: A systematic review.

OBJECTIVE: The purpose of this systematic review was to synthesize the available literature concerning the reliability of three-dimensional superimposition methods when assessing changes in craniofacial hard tissues. MATERIALS AND METHODS: Four electronic databases were searched. Two authors independently reviewed potentially relevant articles for eligibility. Clinical trials, cohort, case-control, and cross-sectional studies that evaluated the reliability of three-dimensional superimposition methods on the anterior cranial base were included. RESULTS: Six studies fulfilled the inclusion criteria. Four studies used the voxel-based registration method, one used the landmark-based method and one used the surface-based method. Regarding reliability, the voxel-based studies showed on average a difference of 0.5 mm or less between images. The optimized analysis using a six-point correction algorithm in the landmark-based method showed 1.24 mm magnitude of error between images. CONCLUSIONS: Although reliability appears to be adequate, the small sample size and high risk of bias among studies make available evidence still insufficient to draw strong conclusions.

Growth changes in the anterior and middle cranial bases assessed with cone-beam computed tomography in adolescents.

INTRODUCTION: Initially, cone-beam computed tomography images from dry skulls were used to 3 dimensionally evaluate intrarater and interrater reliabilities and accuracy of selected 3-dimensional landmarks located in the anterior and middle cranial bases. Thereafter, dimensional changes of the anterior and middle cranial bases with growth were evaluated by using the previously selected landmarks. METHODS: Cone-beam computed tomography images of 10 dry skulls were used to identify useful landmarks from different areas of the anterior and middle cranial bases based on their reliability and accuracy. These selected landmarks were identified in the images of an already available sample of adolescents (n = 60) taken at 2 time points (19 months apart) to assess dimensional changes with growth. RESULTS: The majority of the proposed 3-dimensional landmarks with the exception of the lesser wing of the sphenoid showed acceptable intrarater and interrater reliabilities. The distances measured between foramina and canals in the transverse dimension showed evidence of increases in size. However, the mean amounts of increase in these transverse distances were equal to or less than 1.05 mm (from 1.1% to 4.1%). No change was observed between the right and left anterior and posterior clinoid processes. The vertical dimensions showed evidence of some changes, but these were within 2% of the original distances. CONCLUSIONS: In this adolescent sample, minor growth-related changes were observed in the anterior and middle cranial bases. The midsagittal area of the anterior cranial base (foramen caecum to presphenoid) was stable. The right and left anterior and posterior clinoid processes can be used for transverse superimposition.

Classifications of mandibular canal branching: A review of literature.

AIM: To gather existing radiographic classifications of mandibular canals branching, considering the criteria on which these were based. METHODS: The search for studies on mandibular canals based on imaging exams included literature reviews, epidemiological studies of prevalence, descriptive studies, or case reports. An electronic search in the MEDLINE (OvidSP), PubMed, EMBASE (OvidSP), Web of Science (Thompson Reuters), and Scopus (Elsevier) databases was performed, as well as a manual evaluation of the references of the selected articles. Combinations of key words were placed in each database. No restrictions were imposed regarding the year of publication or language. References collected in duplicate were removed by the authors. A table was drawn up, containing the included studies and respective interest data. RESULTS: Six classifications of mandibular canals branching were selected for the present literature review. Four were based on two-dimensional radiographic exams, and two were performed based on three-dimensional tomographic exams. Three-dimensional classifications were determined based on the analysis found in the least number of exams, comparatively to two-dimensional studies. The prevalence of mandibular canal branching varied from 0% to 38.75% in the works based on two-dimensional exams, while those found in three-dimensional exams ranged from 15.6% to 65%. The studies were mostly referred to branches that began in the mandibular ramus. Just one classification considered the branches that began in the mandibular body region. CONCLUSION: Three-dimensional exams appear to be the best method to view mandibular canal branching. Further studies are warranted to determine its true prevalence and questions concerning to associations.

Three-dimensional cephalometric superimposition of the nasomaxillary complex.

INTRODUCTION: Two-dimensional maxillary superimposition techniques have been routinely used in clinical practice, but a 3-dimensional plane has yet to be introduced and validated. The purposes of this study were to propose a new plane for regional superimposition of the maxillary complex and then to validate it through clinical data. METHODS: Pretreatment and posttreatment palatal expansion records were used. The magnitudes of the transverse expansion at the levels of the first premolars and the first molars were assessed using the proposed superimposition plane and then were compared with the gold standard plaster model measurements. Descriptive statistics and agreement testing were performed to compare the methods. RESULTS: When comparing the superimposition and plaster measurement methods, the mean errors for intermolar and interpremolar distances were 0.57 and 0.59 mm, respectively. Both the intraclass correlation coefficient and the Bland-Altman plot demonstrated high agreement between the 2 methods (intraclass correlation coefficient greater than 0.9). CONCLUSIONS: The proposed maxillary superimposition plane yields clinically suitable results when compared with the gold standard technique, with a mean error of less than 0.6 mm for typical intra-arch measurements. This new landmark-derived maxillary plane for superimposition is a promising tool for evaluating maxillary dentoalveolar changes after treatment.

Anterior cranial-base time-related changes: A systematic review.

INTRODUCTION: The anterior cranial base has long been considered a stable reference structure for superimposing radiographs. However, some studies have questioned its stability. Therefore, the purposes of this systematic review were to give an overview of the studies evaluating growth and development of the anterior cranial base, assess their methodologic quality, and evaluate their validity and accuracy. METHODS: Medline, Embase, and Google Scholar were searched without limitations up to June 2013. Additionally, the bibliographies of the finally selected articles were hand searched to identify any relevant publications that were not identified before. The lowest levels of evidence accepted for inclusion were cohort and cross-sectional studies. RESULTS: A total of 11 articles met all inclusion criteria. They were published between 1955 and 2009. The sample sizes of these studies ranged from 28 to 464 subjects. Their methodologic quality ranged from moderate to low. CONCLUSIONS: Sella turcica remodels backward and downward, and nasion moves forward because of the increase in size of the frontal sinus. These events lead to a continuous increase in the length of the cranial base until adulthood. The presphenoid and cribriform plate regions can be considered stable after age 7, making them the best cranial-base superimposition areas.

Evaluación de la microdureza superficial de una resina compuesta según fuente de luz, su opacidad y tiempo de exposición / Microhardness evaluation of composite resin by light source, opacity and exposure time

El objetivo de este estudio fue comparar la microdureza superficial de una resina compuesta según el tipo de lámpara o fuente de luz, opacidad y tiempo de exposición. Se utilizaron la lámpara halógena Astralis® 10 (Ivoclar Vivadent) y la lámpara LED BluePhase® (Ivoclar Vivadent). Se utilizó la resina microhíbrida 4Season® (Ivoclar Vivadent) en los colores Enamel Trans Super Clear (ETSC), Enamel A2 (A2E), Dentin A2 (A2E). El tiempo de exposición empleado fue de 20s, 40s y 60s. Se confeccionaron 5 muestras de 5x5x2 mm por cada grupo de estudio. Las muestras se almacenaron durante 24 horas en un recipiente seco y oscuro después de la polimerización. Las muestras se evaluaron utilizando la prueba de microdureza Vickers conun microdurómetro HMV-2 (Shimadzu, Kyoto, Japón), en la superficie superior e inferior. Los datos fueron analizados a través de la prueba ANOVA/Tukey. Para detectar diferencias entre las superficies se empleó el análisis t de Student para muestras pareadas. Los mayores valores de microdureza superficial fueron para la resina Enamel Trans Super Clear. La lámpara halógena proporcionó mayores valores de microdureza superficial. Para las lámparas LED o hubo diferencia significativa a los 20s, 40s y 60s. Para la lámpara halógena a los 20s se obtuvo los menores valores de microdureza; entre 40s y 60s no hubo diferencia significativa.

The aim of this study was to compare the surface microhardness of a composite resin according to the light source, opacity and time of exposure. The halogen lamp Astralis® 10 (IvoclarVivadent), BluePhase® LED lamp (Ivoclar Vivadent), and a microhybrid composite resin 4Season (Ivoclar Vivadent) in colors Enamel Trans Super Clear (ETSC), Enamel A2 (A2E), Dentin A2 (A2E) were used. The exposure times used were 20s, 40s and 60s. For each group, five samples of 5x5x2 mm were made. After the polymerization, the samples were stored for 24 hours in a dry and dark container. The samples were evaluated using Vickers microhardness test through the HMV-2 microhardmeter (Shimadzu, Kyoto, Japan) on the upper and lower surface. The data were analyzed by ANOVA test (Tukey). The student's t paired samples was used to detect differences between the surfaces. The resin Enamel Super Clear Trans has the highest values forsurface microhardness. Halogen lamp supplies the highest values of surface microhardness. For the LED lamp there was not significant difference at 20s, 40s and 60s.The halogen lamp at 20sobtain lowest values for surface microhardness; between 40s and 60s there were not significant difference.

Efecto de recarga de cuatro agentes fluorados sobre un ionómero-resina / Recharge effect of four fluoride agents on a resin modified ionomer

El presente estudio in vitro midió la cantidad de fluoruro liberado por un ionómero- resina Fuji Ortho LC bajo los efectos de los vehículos de recarga (gel, enjuague bucal, pasta dental y barniz) durante un periodo de 21 días. Se prepararon 25 muestras en forma de placas rectangulares de 15 mm x 10 mm x 1 mm. Se sumergió cada placa en ml de agua deionizada y se mantuvo a 37°C durante todo el estudio. El agua deionizada fue renovada luego de cada medición. Previa estabilización de la solución con 5 ml del buffer Tisab III, se realizaron mediciones diariamente por los primeros 5 días y a los 10, 15 y 21 días del estudio, en mV con un electrodo selectivo de fluoruro acoplado a un analizador iónico. Se fluorizaron 5 muestras al inicio y cada cinco días con gel fluorado; otras 5 muestras con enjuague bucal; otras 5 con pasta dental; y otras 5 con barniz. Análisis estadísticos fueron hechos con las pruebas de Kruskall-Wallis, "r" de Pearson y Wilcoxon. Los resultados indican que todas las muestras presentaron la mayor cantidad acumulada de fluoruro liberado en el primer día que luego mostró una tendencia a disminuir, las muestras con gel y barniz liberaron la mayor y menor cantidad respectivamente. Se encontró que el efecto de recarga por parte de los vehículos hace que el material aumente su liberación de fluoruro en el momento de aplicación para posteriormente disminuirla.

Estudio in vitro de la radiopacidad de los cementos de ionómero de vidrio comparada con dentina y esmalte / In vitro study of radiopacity of glass ionomer cements compared with dentine and enamel

El objetivo del presente estudio fue determinar la radiopacidad de los ionómeros de vidrio comparados con esmalte y dentina. Se utilizó un tercer molar permanente del cual se obtuvo un modelo en yeso extraduro con una preparación cavitaria oclusomesial de 3 milímetros de extensión bucopalatina y 4 milímetros de profundidad, en el cual se prepararon retauraciones indirectas utilizando los ionómeros: Ketac Molar (ESPE), Fuji IX (GC-América), Chemflex (Dentsply), Medifil IX (Promédica), Fuji II LC (GC-América) y Vitremer (3M). Se prepararon cilindros de 3 mm de grosor y 5 mm de diámetro de cada material. se tomaron registros radiográficos digitales con una distancia cono-placa de 5 centímetros de las diferentes muestras, se utilizó un captador CCD con fibra óptica (RVG by Trophy, Francia) de 41 x 25 mm. Cada imagen digital incluyó al diente con una muestra, los cilindros de cada material y uno de aluminio. Las imágenes fueron analizadas en el programa Trophy 2000. Los datos obtenidos fueron sometidos al análisis de varianza (ANOVA) donde se encontraron diferencias estadísticamente significativas entre los materiales y las estructuras dentarias. Todas las muestras presentaron una radiopacidad menor a la del esmalte. El ionómero Fuji IX fue el material más aceptable por presentar una radiopacidad intermedia entre el esmalte y dentina.