Guy Willems

THROMBOLYSIS WITH TISSUE PLASMINOGEN ACTIVATOR IN ACUTE MYOCARDIAL INFARCTION: NO ADDITIONAL BENEFIT FROM IMMEDIATE PERCUTANEOUS CORONARY ANGIOPLASTY

A randomised trial of 367 patients with acute myocardial infarction was performed to determine whether an invasive strategy combining thrombolysis with recombinant tissue-type plasminogen activator (rTPA), heparin, and acetylsalicylic acid, and immediate percutaneous transluminal coronary angioplasty (PTCA) would be superior to a noninvasive strategy with the same medical treatment but without immediate angiography and PTCA. Intravenous infusion of 100 mg rTPA was started within 5 h after onset of symptoms (median 156 min). Angiography was performed 6-165 min later in 180 out of 183 patients allocated to the invasive strategy; 184 patients were allocated to the non-invasive strategy. Immediate PTCA reduced the percentage stenosis of the infarct-related segment, but this was offset by a high rate of transient (16%) and sustained (7%) reocclusion during the procedure and recurrent ischaemia during the first 24 h (17%). The clinical course was more favourable after non-invasive therapy, with a lower incidence of recurrent ischaemia within 24 h (3%), bleeding complications, hypotension, and ventricular fibrillation. Mortality at 14 days was lower in patients allocated to non-invasive treatment (3%) than in the group allocated to invasive treatment (7%). No difference between the treatment groups was observed in infarct size estimated from myocardial release of alpha-hydroxybutyrate dehydrogenase or in left ventricular ejection fraction after 10-22 days. Since immediate PTCA does not provide additional benefit there seems to be no need for immediate angiography and PTCA in patients with acute myocardial infarction treated with rTPA.

A classification of dental composites according to their morphological and mechanical characteristics

The on-going search for a biologically acceptable restorative material has brought a confusing variety of composites on the dental market. In the present study, commercially available composites are categorized as a function of their mean particle size, filler distribution, filler content, Youngs modulus, surface roughness, compressive strength, surface hardness, and filler morphology. Out of this information, it can be concluded that the materials of choice for restoring posterior cavities at present are the Ultrafine Compact-Filled Composites because their intrinsic surface roughness, Youngs modulus and, indirectly, their filler content, compressive strength, and surface hardness are comparable to the same properties of enamel and dentin. The Ultrafine Midway-Filled Composites seem to be very satisfactory materials for anterior use.

Dental age estimation in Belgian children: Demirjian's technique revisited.

AIM The purpose of this study was to evaluate the accuracy of Demirjians dental age estimation in children in a Belgian Caucasian population and to adapt the scoring system in case of a significant overestimation as frequently reported. We selected 2523 orthopantomograms of 1265 boys and 1258 girls, of which 2116 (1029 boys and 1087 girls) were used for estimating the dental age with the Demirjians technique. The 407 other orthopantomograms were beyond the original age limit. A second sample of 355 orthopantomograms was used to evaluate the accuracy of the original method and the adapted method. A signed-rank test was performed to search for significant age differences between the obtained dental age and the chronological age. A weighted ANOVA was performed in order to adapt the scoring system for this Belgian population. The overestimation of the chronological age was confirmed. The adapted scoring system resulted in new age scores expressed in years and in a higher accuracy compared to the original method in Belgian Caucasians.

Third molar root development in relation to chronological age: a large sample sized retrospective study

The aim of the present investigation, which is a continuation and extension of a previous published pilot study [Forensic Sci. Int. 129 (2002) 110], was to calculate the chronological age of an individual based on the dental developmental stages of third molars (so-called wisdom teeth). The evaluated material consisted of 2513 orthopantomograms (OPGs) of patients all of Belgian Caucasian origin between 15.7 and 23.3 years. The sample of OPGs was scored by two observers who were calibrated for intra- and interobserver reliability by means of kappa statistics. The kappa statistics revealed a strong agreement between the intra- and interobserver measurements. Further statistical analysis was performed in order to obtain multiple regression formulae for dental age calculation with the chronological age as the independent variable and the third molar developmental stages as dependent variables. Both for males and females a significant Pearson correlation coefficient was noticed for contralateral third molars, a smaller less significant one for the antimeres. For the application of the regression formulae one has to take into consideration the gender, the location and number of wisdom teeth. Probabilities for an individual to be older than 18 years were also calculated in case of fully developed wisdom teeth.

Timing of Demirjian's tooth formation stages

Background: Global differences in Demirjian et al.s method of assessing dental maturity are thought to be due to population differences. Aim: The aim of this study was to investigate the timing of individual tooth formation stages in children from eight countries. Research design: This was a meta-analysis of previously published data from retrospective cross-sectional studies of dental maturity. Method: Data of mandibular permanent developing teeth from panoramic radiographs (Demirjians stages) were combined from Australia, Belgium, Canada, England, Finland, France, South Korea and Sweden (n = 9002, ages 2–16.99 years). Age-of-attainment was calculated using logistic regression for each group by sex and meta-analysis of the total. Overlapping 95% confidence intervals of the means was interpreted as no significant difference. Results: Mean ages for each group and total were significantly different in 65 out of 509 comparisons (p < 0.05). Some of these were of small sample size but there was no consistent pattern. Apex closure of the first molar was significantly later in children from Quebec and this might explain differences found in the dental maturity score. Conclusions: These results suggest no major differences in the timing of tooth formation stages between these children. This fails to explain previous findings of differences using Demirjians dental maturity method. Résumé.Arrière plan: On pense que les différences globales dans la méthode de Demirjian et al. d’appréciation de la maturité dentaire sont dues à des différences entre populations. Objectif: Cette étude a pour objet d’observer la chronologie individuelle des stades de formation de la dent chez des enfants de huit nations. Type de recherche: Il s’agit d’une méta-analyse de données d’enquêtes transversales rétrospectives de maturité dentaire déjà publiées Méthode: Des données de radiographie panoramique de dents permanentes mandibulaires en voie de développement (stades de Demirjian) ont été recueillies en Autriche, Belgique, Canada, Angleterre, Finlande, France, Corée du Sud et Suède (n = 9002, âges de 2 à 16,99 ans). L’âge d’atteinte a été calculé au moyen de régressions logistiques pour chaque groupe par sexe et par méta-analyse de la totalité. Résultats: Les ages moyens de chaque groupe et de l’ensemble sont significativement différents dans 65 comparaisons sur 509 (p <0,05). Quelques différences sont de faible ampleur, mais sans qu’on puisse leur attribuer une signification particulière. La fermeture de l’apex de la première molaire est significativement plus Tardif chez les enfants du Québec, ce qui pourrait expliquer les differences observées dans les scores de maturité dentaire. Conclusion: Ces résultats suggèrent qu’il n’existe pas de différence majeure entre ces enfants dans la chronologie des stades de formation dentaire. Il n’est donc pas possible d’expliquer les différences trouvées dans des études antérieures par la méthode de maturité dentaire de Demirjian. Zusammenfassung.Hintergrund: Globale Unterschiede bei der Methode nach Demirjian et al. zur Bestimmung der Zahnreife werden ethnischen Unterschieden zugeschrieben. Ziel: Das Ziel dieser Studie war, die zeitliche Abfolge der individuellen Zahnentwicklung bei Kindern aus acht Ländern zu untersuchen. Untersuchungsaufbau: Dies war eine Meta-Analyse früher publizierter Daten aus retrospektiven Querschnittsuntersuchungen zur Zahnreife. Methode: Es wurden Daten aus Australien, Belgien, Kanada, England, Finnland, Frankreich, Südkorea und Schweden von Panorama-Röntgenaufnahmen der unteren bleibenden Zähne (Demirjian-Stadien) (n = 9002, Alter 2–16,99 Jahre) zusammengefasst. Das Alter zum Zeitpunkt des Zahndurchbruchs wurde unter Verwendung einer logistischen Regression geschlechtsspezifisch für jede Gruppe gerechnet und eine Meta-Analyse des gesamten Datensatzes vorgenommen. Überlappungen der 95%-Vertrauensintervalle von Mittelwerten wurden im Sinne nicht-signifikanter Unterschiede gedeutet. Ergebnisse: Mittleres Alter für jede Gruppe und insgesamt waren bei 65 von 509 Vergleichen signifikant unterschiedlich (p < 0,05). Einige Stichproben waren klein, aber es gab hier kein durchgehendes Muster. Der Zahnschluss der ersten Molaren war bei Kindern aus Quebec signifikant später, und dies könnte die beobachteten Unterschiede im Zahnreifungs-Score erklären. Zusammenfassung: Diese Ergebnisse legen nahe, dass es keine wesentlichen Unterschiede in der zeitlichen Abfolge der Zahnentwicklung dieser Kinder gibt. Damit wurden früher beobachtete Unterschiede bei Anwendung der Zahnreifebestimmungsmethode nach Demirjian nicht bestätigt. Resumen. Antecedentes: Se cree que las diferencias globales en el método de Demirjian et al. para estimar la madurez dental son debidas a diferencias poblacionales. Objetivo: El objetivo de este estudio fue investigar el momento de aparición de los estadios de formación dental individual en niños de ocho países. Diseño de la investigación: La investigación consistió en un meta-análisis de datos previamente publicados procedentes de estudios transversales retrospectivos de madurez dental. Método: Se combinaron datos de dientes permanentes en desarrollo de la mandíbula, a partir de radiografías panorámicas (estadios de Demirjian) procedentes de Australia, Bélgica, Canadá, Inglaterra, Finlandia, Francia, Corea del Sur y Suecia (n = 9.002, edades de 2,00--16,99 años). La edad de finalización se calculó utilizando una regresión logística para cada grupo y sexo y un meta-análisis del total. Un solapamiento del 95% de los intervalos de confianza de las medias se interpretó como que no existía ninguna diferencia significativa. Resultados: Las edades medias para cada grupo y para el total fueron significativamente diferentes en 65 de las 509 comparaciones (p <0,05). Algunas de éstas fueron de pequeño tamaño muestral, pero no existía un patrón consistente. El cierre apical del primer molar fue significativamente más tardío en los niños de Québec y esto podría explicar las diferencias encontradas en la puntuación de la madurez dental. Conclusiones: Estos resultados sugieren la no existencia de diferencias importantes en el momento de aparición de las etapas de la formación del diente entre estos niños. Esto no permite explicar los resultados previos sobre las diferencias observadas cuando se usa el método de la madurez dental de Demirjian.

Comparison of two cone beam computed tomographic systems versus panoramic imaging for localization of impacted maxillary canines and detection of root resorption

The diagnostic accuracy for the localization of impacted canines and the detection of canine-induced root resorption of maxillary incisors were compared between conventional radiographic procedures using one two-dimensional (2D) panoramic radiograph with that of two three-dimensional (3D) cone beam computed tomography (CBCT) scans. The clinical records of 60 consecutive patients who had impacted or ectopically erupting maxillary canines were identified from those seeking orthodontic treatment. For each case, two sets of radiographic information were obtained. The study sample was divided into two groups: group A (n = 30) included those for whom a dental pantomograph (DPT) and CBCT obtained with a 3D Accuitomo-XYZ Slice View Tomograph were available and group B (n = 30) who had a DPT and CBCT obtained with a Scanora. The DPT and CBCT images were subsequently analysed by 11 examiners. Statistical analysis included an evaluation of the agreement between observers based on the standard error of the measurement, kappa statistics and coefficient of concordance, as well as an assessment of the differences between 2D and 3D imaging employing Wilcoxon signed rank and McNemar tests. There was a highly significant difference between the 2D and 3D images in the width of the canine crown (P < 0.001) and in canine angulation to the occlusal plane. Moreover, there was a highly significant difference between the DPT and Scanora CBCT images in canine angulation to the midline (P < 0.001). There was also a significant difference between 2D and 3D images with respect to canine location (P = 0.0074 for group A and P = 0.0008 for group B). The presence or absence of root resorption of the lateral incisor was also significantly different in both groups (P = 0.0201 and P < 0.001 for groups A and B, respectively). Detection of central incisor root resorption was significantly different between the Accuitomo and DPT images (P = 0.045). There was also a significant difference in the severity of lateral incisor root resorption between the DPT and CBCT in both groups (P = 0.02). The results of this study suggest that CBCT is more sensitive than conventional radiography for both canine localization and identification of root resorption of adjacent teeth.

Dental abnormalities, bone graft quality, and periodontal conditions in patients with unilateral cleft lip and palate at different phases of orthodontic treatment.

OBJECTIVES To evaluate the dental and periodontal condition of patients with unilateral cleft lip and palate (UCLP) before orthodontic treatment and evaluate whether the dental and periodontal condition of these patients during and after orthodontic treatment was jeopardized by the duration of the orthodontic and surgical treatment. DESIGN Seventy-five individuals with UCLP (52 males, 23 females), between ages 8 and 20 years, participated in a retrospective study during their final follow-up visit with regard to dental abnormalities, such as hypodontia, external root resorption, crown and root malformation, and supernumerary teeth. Alveolar bone height and periodontal attachment loss on the cleft side were also screened before or after bone grafting and at different stages of orthodontic treatment. RESULTS Hypodontia of the lateral incisor was found in more than 50% of the patients on the cleft side. Second premolars and/or lateral incisors outside the cleft area were missing in 27.2% of the patients. In 32%, malformations of the teeth near the cleft were noticed. In general, the teeth around and in the cleft of the patients showed normal septal bone heights and a healthy periodontium. Sixty of the 75 patients received a bone graft to restore the interrupted alveolar process. In 93.3% of these patients, the cleft was grafted before the eruption of the canine. CONCLUSION The periodontium of the teeth in and around the cleft in patients with UCLP observed during and after orthodontic treatment can cope relatively well with the long orthodontic treatment and combined surgical interventions. The children, who had not yet started treatment, also showed enough bone support and no periodontal problems of the teeth besides the cleft. Early secondary bone grafting seems to give optimal periodontal results.

Hypodontia and tooth formation in groups of children with cleft, siblings without cleft, and nonrelated controls

OBJECTIVE To compare the occurrence of hypodontia, dental age, and asymmetric dental development in children with cleft with their siblings and a nonsibling control group. SUBJECTS The sample consisted of 54 children with cleft (aged 4.2 to 13.1 years), who had at least one sibling available for an orthopantomogram, 63 siblings without cleft (aged 4 to 14.9 years) and 250 controls without cleft (aged between 4 and 14.9 years). METHOD Hypodontia, dental age, and asymmetric dental development were assessed on panoramic radiographs of the children with cleft, the siblings without cleft, and the control children without cleft. RESULTS Both the cleft (p <.001) and the sibling group (p <.05) showed a significantly higher frequency of hypodontia and a significantly higher occurrence (cleft p <.01 and sibling group p <.001) of asymmetric dental development, compared with the control group. Only a small, but insignificant, delay in dental development could be found in the cleft and the sibling group. CONCLUSIONS; The cleft subjects with siblings showed a significantly higher occurrence of hypodontia and asymmetric dental development than the noncleft control group. This may suggest a genetic component for the occurrence of hypodontia and asymmetric dental development.

In-vitro comparison of 2 cone-beam computed tomography systems and panoramic imaging for detecting simulated canine impaction-induced external root resorption in maxillary lateral incisors

INTRODUCTION The introduction of cone-beam computed tomography (CBCT) in dentomaxillofacial radiology has created new diagnostic challenges, including some potential opportunities for evaluating impacted teeth. The diagnostic accuracy for detection of simulated canine-induced external root resorption lesions in maxillary lateral incisors was compared between conventional 2-dimensional panoramic radiographic imaging and two 3-dimensional CBCT systems. METHODS A child cadaver skull in the early mixed dentition was obtained from the Department of Anatomy, Hasselt University, Diepenbeek, Belgium, with ethical approval. This skull had an impacted maxillary left canine and allowed a reliable simulation. Simulated root resorption cavities were created in 8 extracted maxillary left lateral incisors by the sequential use of 0.16 mm diameter round burs in the distopalatal root surface. Cavities of varying depths were drilled in the middle or apical thirds of each tooth root according to 3 setups: slight (0.15, 0.20, and 0.30 mm), moderate (0.60 and 1.00 mm), and severe (1.50, 2.00, and 3.00 mm). The lateral incisors, including 2 intact teeth, were repositioned individually in the alveolus of the pediatric skull with approximal contacts to the impacted maxillary left canine. Three sets of radiographic images were obtained with panoramic Cranex Tome (Soredex, Helsinki, Finland), Accuitomo-XYZ Slice View Tomograph (J. Morita, Kyoto, Japan), and Scanora 3D CBCT (Soredex, Tuusula, Finland) for each tooth setup. Eight observers examined the 3 sets of 10 radiographs for resorption cavities. RESULTS The differences in correct detection of simulated root resorption for all cavity sizes were significantly different (P <0.05) between the panoramic and both CBCT systems. CBCT imaging performance was significantly better than that of panoramic radiography for determining root resorption in the categories of slight and severe resorption. CONCLUSIONS These results suggest that the CBCT radiographic method is more sensitive than conventional radiography to detect simulated external root resorption cavities.

Root resorption of the maxillary lateral incisor caused by impacted canine: a literature review

Root resorption of maxillary lateral incisors caused by erupting canines is well known and a relatively common phenomenon. However, much debate and conflicting evidence exists with regard to the actual resorption trigger and potential etiological factors involved. Consequently, there are no obvious clinical clues concerning prevention and diagnosis as well as subsequent treatment decisions. The introduction of cone beam computer tomography has recently allowed drawing a new and much more documented light on the diagnostic and therapeutic strategies. However, no investigations have determined that this new information may result in another and better diagnostic approach and an improved treatment outcome. Therefore, the present review will attempt to summarize the existing evidence on two- and three-dimensional images and try to link the radiological observations to any further preventive, diagnostic, and/or therapeutic measures. Detection thresholds, accuracy, and reliability of impacted canine localization and neighboring root resorption risks will also be considered. This review demonstrates how adding a third-dimension to the radiographic information may notably alter the prevalence of root resorptions and descriptions of this prevalence. In any case, further investigation is needed to determine resorption detection thresholds in various two-dimensional and three-dimensional imaging techniques, as well as to determine therapeutic thresholds and criteria for strategic tooth extraction based on radiographic manifest and not manageable resorption lesions.