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Premolars
Kinds of Premolars Terms modified by Premolars Selected AbstractsAge and gender-related differences in premolar and molar functional areasJOURNAL OF ORAL REHABILITATION, Issue 4 2007P. BOURDIOL summary, The aim of the present study was to underline the difference in premolar,molar functional areas according to both age and gender in a human adult population. Premolar and molar series were marked manually on opposed casts with articulating paper and functional areas were evaluated by quantification of these markings. It was noticed that on average larger functional areas were displayed by the older group (19 individuals, mean age 71·2 years, minimum 68 years, maximum 73 years) in comparison with the younger one (24 individuals, mean age 27·4 years, minimum 22 years; maximum 33 years). It was also observed that the average total functional area (4 hemiarches) was larger in the male subgroup (n: 23; mean age 45; young adults, 14; old adults, 9) compared with the female one (n: 20; mean age 49; young adults, 10; old adults, 10). Nevertheless, this gender difference in premolar,molar functional areas was related to the individual occlusal areas. As a matter of fact, when the individual occlusal area was taken into account for each series in the form of a ratio (functional area/occlusal area), the values obtained were not different between both gender subgroups studied. When comparing premolar and molar functional ratios (functional area/occlusal area) between age groups, it appears that the values obtained were slightly higher for the premolar series (ratios for young and older adults, respectively: Premolar series: 23·6 ± 7·5%, 30 ± 6·5%; Molar series: 23·1 ± 6·8%, 27·3 ± 6·7%). This difference was interpreted in relation to the reference (occlusal area) chosen. [source] Spontaneously healed horizontal root fracture in maxillary first premolar: report of a caseDENTAL TRAUMATOLOGY, Issue 2 2007Funda Kont Çobankara Abstract,,, Root fractures of the posterior teeth are rare and occur as a result of severe trauma. This study describes the horizontal root fracture of a maxillary first premolar. The fractured roots were discovered during a routine radiographic examination. The tooth was asymptomatic and responded positively to electric pulp testing. The patient reported accidental trauma, which occurred 14 years before. Our case is an example of spontaneously healed fractured roots. The interesting findings were that the healing was observed even in the presence of two roots, including preservation of the vitality of the pulp. [source] Repair of untreated horizontal root fracture: a case reportDENTAL TRAUMATOLOGY, Issue 5 2003Murat Özbek Abstract ,,,We report a clinical case of horizontal root fracture in the mandibular first premolar induced by a traffic accident. The fractured tooth spontaneously healed and diagnosed radiographically after 2 years. Fractured fragments were separated by a narrow radiolucent line and the edges were rounded, and healing of the tooth is likely to be related to interproximal connective tissue healing. Our case is an example of spontaneously healed fracture roots. An interesting finding is that the healing was observed even in the presence of two root canals, the vitality of the pulp was preserved and displacement of fragments were prevented. [source] The lateral periodontal cyst: aetiology, clinical significance and diagnosisDENTAL TRAUMATOLOGY, Issue 4 2000N. P. Kerezoudis Abstract , The lateral periodontal cyst (LPC) is a relatively uncommon but widely recognized odontogenic cyst of developmental origin. It is found mostly in adults and has no sex predilection. LPC is usually discovered during routine radiographic examination, is located mainly between the roots of vital mandibular canines and premolars, and seldom causes pain or other clinical symptoms. The defect appears on radiographs as a round or teardrop-shaped, well circumscribed radiolucency. Due to its location it can easily be misdiagnosed as a lesion of endodontic origin. In this paper, two cases of lateral periodontal cysts are presented. In the first case, the patient (woman, 62 years old) complained of an asymptomatic gingival swelling in the region between the right maxillary canine and premolar. The radiographic examination revealed a well circumscribed radiolucency with a radiopaque margin between the roots of the canine and premolar. The adjacent teeth had vital pulp. Surgical enucleation of the lesion was performed and the histological examination revealed that the lesion was a "lateral periodontal cyst of developmental origin". In the second case, the patient (woman, 44 years old) compained of a swelling in the area of tooth 32. During radiographic examination a well circumscribed radiolucency between the roots of the lateral incisor and the canine was discovered. Surgical enucleation of the lesion was performed and the histological examination revealed that the lesion was a "lateral periodontal cyst of developmental origin". [source] External skeletal fixation in the management of equine mandibular fractures: 16 cases (1988,1998)EQUINE VETERINARY JOURNAL, Issue 2 2001K. A. BELSITO Summary Fifty-three cases of equine mandibular fractures were managed surgically from 1988,1998, of which 16 (30%) were repaired by external skeletal fixation (ESF). Three surgical methods were utilised: transmandibular 4.76 or 6.35 mm Steinmann pins incorporated into fibreglass casting material or nonsterile dental acrylic (methyl methacrylate - MMA) bars reinforced with steel; transmandibular 9.6 mm self-tapping threaded pins ± 4.76 or 6.35 mm Steinmann pins incorporated into MMA bars reinforced with steel; and 4.5 mm or 5.5 mm ASIF cortical bone screws incorporated into MMA bars reinforced with steel or a ventral MMA splint. Fourteen horses were presented to the hospital for fixator removal at an average of 56.2 days. At removal, fractures were stable and occlusion of incisor and cheek teeth was considered adequate. Complications of the procedure occurred in 3 horses. Two horses with persistent drainage and ring sequestra from pin tracts required curettage 4 or 5 months after ESF removal. A third horse required replacement of the original fibreglass ESF with MMA bars to regain access to open, infected wounds. Another horse required removal of the second premolar at the time of fixator removal because the tooth root had been damaged in the original injury. ESF for the surgical management of mandibular fractures in horses has produced good results, with incisive and cheek tooth alignment reestablished in all horses. Horses that were managed via ESF had a rapid return to full feed and did not require any supplementation via nasogastric tube or oesophagostomy to maintain bodyweight or hydration status. [source] Development of heterodont dentition in house shrew (Suncus murinus)EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2007Atsushi Yamanaka Mammalian heterodont dentition comprises incisors, canines, premolars, and molars. Although there has been intensive research, the patterning of these specific tooth types has not yet been elucidated. In order for the gene expression data to be linked with tooth type determination, it is first necessary to determine precisely the incisor-, canine-, premolar-, and molar-forming regions in the jaw primordia. To accomplish this, we studied dentition development in the house shrew (Suncus murinus), which has retained all the tooth types, using three-dimensional reconstructions from serial histological sections and the Sonic hedgehog (Shh) expression patterns. Before the appearance of morphological signs of odontogenesis, Shh expression localized to the presumptive tooth-forming regions, in which the mesial and distal expression domains corresponded to the incisor- and premolar-forming regions, respectively. The upper incisor region was found to extend across the boundary between the frontonasal and the maxillary processes. The canine-forming regions later appeared in the intermediate portions of the maxillary and the mandibular processes. The molar-forming regions later appeared distal to the initially demarcated tooth-forming regions by secondary extension of the distal ends. The demarcation visualized by the Shh expression pattern in the jaw primordia of the house shrew probably represents the basic developmental pattern of mammalian heterodont dentition. [source] Factors influencing proximal dental contact strengthsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 5 2000Christof E. Dörfer The aim of this study was to systematically measure proximal contact strength in complete natural dentitions of 30 adults (25.3±3.0 years of age), and to analyze its relationship to tooth type, tooth location, chewing effort and time of day variation. The contact strengths were measured dynamically during removal of a calibrated 0.05-mm-thick metal strip between the proximal contacts of adjacent teeth. Proximal contact strengths were lower in the maxilla (2.51±1.36 N) compared to the mandible (4.26±1.88 N). Within the jaws, the lowest proximal contact strength was measured between canine and first premolar (2.91±1.79 N) and the highest between second premolar and first molar (3.73±1.95 N). Chewing increased the proximal contact strength within the maxilla (before: 2.51±1.36 N, after: 3.02±1.45 N) but it remained unchanged in the mandible (before: 4.26±1.88 N, after: 4.22±1.85 N). The proximal contact strength increased significantly from morning (3.39±1.86 N) to noon (3.61±1.77 N), and then decreased in the afternoon (3.43±1.60 N). It was concluded that proximal contact strength can be significantly influenced by location, tooth type, chewing and time of day variation. Based on the differences in distribution due to the effect of chewing and time of day, it is speculated that proximal contact strength is a physiological entity of multifactorial origin. [source] The taming of the shrew milk teethEVOLUTION AND DEVELOPMENT, Issue 4 2008Elina Järvinen SUMMARY A characteristic feature of mammalian dentition is the evolutionary reduction of tooth number and replacement. Because mice do not replace teeth, here we used Sorex araneus, the common shrew, as a model to investigate the loss of tooth replacement. Historically, shrews have been reported to initiate the development of several, milk or deciduous teeth but these soon become rudimentary and only the replacement teeth erupt. Shrews thus offer a living example of a derived mammalian pattern where the deciduous tooth development is being suppressed. Based on histological and gene expression analyses of serial sections, we suggest that S. araneus has discernible tooth replacement only in the premolar 4 (P4) position. Both generations of teeth express Shh in the enamel knot and in the inner enamel epithelium. Nevertheless, the deciduous P4 (dP4) is reduced in size during embryogenesis and is eventually lost without becoming functional. Analysis of growth shows that P4 replaces the dP4 in a "double-wedge" pattern indicative of competitive replacement where the suppression of the deciduous tooth coincides with the initiation of its replacement. Because activator,inhibitor mechanisms have been implicated in adjacent mouse molars and in transgenic mice with continuous tooth budding, we suggest that evolutionary suppression of deciduous teeth may involve early activation of replacement teeth, which in turn begin to suppress their deciduous predecessors. [source] Anomalous mandibular premolars: a mandibular first premolar with three roots and a mandibular second premolar with a C-shaped canal systemINTERNATIONAL ENDODONTIC JOURNAL, Issue 11 2008B. M. Cleghorn Abstract Aim, To describe unusual variations in the root morphology and root canal systems of mandibular first and second premolar teeth extracted for orthodontic reasons. Summary, Normally mandibular first and second premolar teeth have single roots with single canals. A 15-year-old patient presented for orthodontic treatment and two mandibular premolar teeth were examined post-extraction. The mandibular first premolar exhibited three distinct, separate roots and the mandibular second premolar exhibited a C-shaped root canal system. The coronal morphology of each of the mandibular premolars revealed dimensions and anatomy within normal limits. The incidence of a three-rooted mandibular first premolar is approximately 0.2%. Key learning points ,,Thorough clinical and radiographic interpretation is important in recognizing anomalous root and root canal systems. ,,The most common forms of root and canal systems and its aberrations must be understood to realize variations from normal do occur. ,,Successful root canal treatment requires an accurate diagnosis of the root canal system using all available aids. ,,Value of microcomputed tomography in the study of anatomy ex vivo and cone-beam tomography in clinical endodontics of complex premolar cases is increasing. [source] The effect of the renewal of calcium hydroxide paste on the apexification and periapical healing of teeth with incomplete root formationINTERNATIONAL ENDODONTIC JOURNAL, Issue 7 2005M. C. S. Felippe Abstract Aim, To evaluate the influence of renewing calcium hydroxide paste on apexification and periapical healing of teeth in dogs with incomplete root formation and previously contaminated canals. Methodology, Forty premolars from four 6-month-old dogs were used. After access to the root canals and complete removal of the pulp, the canal systems remained exposed to the oral environment for 2 weeks. Canal preparation was then carried out using Hedströem files, under irrigation with 1% sodium hypochlorite, 1 mm short of the radiographic apex. After drying, the canals of one premolar in each dog were left empty (group 4-control), and those of the other nine teeth in each animal were filled with a calcium hydroxide-propylene glycol paste. All teeth were restored with reinforced zinc oxide cement (IRM) or IRM and amalgam (group 4). The paste was renewed and the teeth restored again 1 week later. Then, the nine teeth in each animal were divided into three experimental groups: group 1 , paste not changed; group 2 , paste renewed every 4 weeks for 5 months; and group 3 , paste renewed after 3 months had elapsed. The teeth were restored with IRM and amalgam (groups 1 and 3) or IRM (group 2). The animals were killed 5 months later, and blocks of the teeth and surrounding tissues were submitted to histological processing. The sections were studied to evaluate six parameters: apical calcified tissue barrier, inflammatory reaction, bone and root resorption, paste extrusion and microorganisms. Results of experimental groups were analysed by Kruskal,Wallis nonparametric tests and by the test of proportions. The critical value of statistical significance was 5%. Results, Significant differences (P < 0.05) were found in relation to the presence of bone resorption and paste in the periradicular area, the formation of a calcified tissue barrier at the apex, and the intensity of the apical inflammatory reaction. Bone resorption was more evident in group 1 (medicament not changed), and the presence of paste in the periodontal tissues was more common in groups 2 and 3. Renewal of the paste reduced the intensity of the inflammatory reaction (groups 2 and 3), but the formation of apical calcified tissue was more noticeable in the teeth where the paste had not been renewed. Conclusions, Replacement of calcium hydroxide paste was not necessary for apexification to occur, however, it did reduce significantly the intensity of the inflammatory process. Monthly renewal of calcium hydroxide paste reduced significantly the occurrence of apexification. [source] Prevalence of apical periodontitis and frequency of root-filled teeth in an adult Spanish populationINTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2004A. Jiménez-Pinzón Abstract Aim, To estimate the prevalence of teeth with apical periodontitis (AP) and root-filled teeth in an adult Spanish population. Methodology, A total of 180 subjects, aged 37.1 ± 15.7 years, presenting as new patients to the Faculty of Dentistry, Seville, Spain, were examined. All participants underwent a full-mouth radiographic survey (14 periapical radiographs). The frequency of root canal treatment and the periapical status of all teeth, using the periapical index (PAI) score, were assessed. An intraobserver agreement test on PAI scores produced a Cohen's kappa of 0.77 (substantial agreement). Results were analysed statistically using the Chi-square test. Results, Apical periodontitis in one or several teeth was found in 110 subjects (61.1% prevalence), and 73 (40.6% prevalence) had at least one root-filled tooth. Among subjects with root-filled teeth, 48 (65.8%) had AP affecting at least one root-filled tooth. A total of 4453 teeth were examined, of these 186 (4.2%) had AP. The total number of root-filled teeth was 93 (2.1%), of which 60 (64.5%) had AP. Among non-root filled teeth, only 2.9% had AP. The prevalence of AP in connection with molar teeth was higher (5.5%) than for premolar (4.5%) and anterior teeth (3.2%; P < 0.01). More premolar and molar teeth were root-filled (2.8 and 2.7%, respectively) than anterior teeth (1.3%; P < 0.01). The prevalence of AP increased with age. Conclusions, The prevalence of AP in root-filled and untreated teeth, and the frequency of root-filled teeth were comparable to those reported in previous similar studies carried out in European countries. The prevalence of root-filled teeth with AP was found to be higher compared to that demonstrated in other epidemiological studies. [source] Endodontic and periodontal treatments of a geminated mandibular first premolarINTERNATIONAL ENDODONTIC JOURNAL, Issue 2 2002S. Aryanpour Abstract Aim, To describe a rare case of gemination involving a mandibular first premolar. Summary The complex morphology of geminated teeth renders their endodontic and periodontal management difficult. Root canal and periodontal treatments were performed on a geminated mandibular first premolar with three canals. Clinical examination showed two separated crowns with united roots. Radiographically, two distinct pulp chambers with two joined and a third independent canal were seen. Conventional root canal treatment resulted in complete healing of the apical lesion. However, the occurrence of a vertical fracture led to the extraction of the mesial segment. At the follow-up visit, the distal segment was clinically healthy and continued to satisfy functional demands. Key learning points ,Failure to diagnose the initial crack along a gemination groove resulted in further propagation and finally complete vertical fracture. ,Owing to the abnormal morphology of the crown and the complexity of the root canal system in geminated teeth, treatment protocols require special attention. ,For asymptomatic cases without aesthetic or orthodontic problems and without associated pathosis, routine review and careful maintenance are required. [source] Life history of a mule (c. 160 AD) from the Roman fort Biriciana/Weißenburg (Upper Bavaria) as revealed by serial stable isotope analysis of dental tissuesINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 2 2010T. E. Berger Abstract The presence of the osseous remains of at least four mules in a garbage dump at the Roman fort of Biriciana near the town of Weißenburg, Upper Bavaria, dating to c. 160 AD, raised the question as to whether mule breeding was already performed to the north of the Alps during the Middle Roman Empire, or whether these animals still had to be imported from the Mediterranean. Serial analyses of the dental enamel and dentine of a lower fourth premolar and the surrounding alveolar bone of a mandible of a mule in terms of stable strontium isotopic ratios of the apatite, and stable carbon and oxygen isotope ratios of the structural carbonate, were carried out to test whether this individual moved long distances during its lifetime. Since isotopic ratios obtained by serial analysis can be correlated with consecutive ontogenetic stages, it can be assumed that this particular individual experienced significant changes in terms of diet and environmental parameters after its eighth year of life. These changes included a period of residence in a region of high altitude, most likely the Alps considering the location of the Roman fort where the mule was found. The isotopic data obtained do not contradict the assumption that this animal was bred and raised in northern Italy, to frequent later in its adult life the Alps and finally perish at Biriciana/Weißenburg. Copyright © 2008 John Wiley & Sons, Ltd. [source] Classification and sequelae of arrested eruption of primary molarsINTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 1 2008INGER KJÆR Aim., The aim of this study was to classify early arrested eruption of primary molars and to analyse and explain the sequelae for the surrounding alveolar bone and the succeeding premolar. Design., The position of the arrested primary molars in the mandible, the height of the local alveolar bone, and the morphology and location of the succeeding premolar were evaluated on radiographs from 29 children. Results., Four groups of arrest from mild to severe with regards to infra-position were categorized (Groups I,IV). Mean ages at the time of referral decreased from Groups I (8 years, 10 months) to Group IV (5 years, 9 months). Sequelae., (i) Reduction of alveolar bone height (Groups I,III); (ii) delayed maturity of the succeeding premolar (two-thirds of the cases); (iii) malformation of the succeeding premolar (mainly Groups III and IV); and (iv) ectopically located premolar occlusal to the retained molar (Group IV). Conclusions., The deeper in the alveolar process a primary molar is retained, the earlier the disturbance in the eruption has occurred, and the greater is the risk of the permanent tooth germ being malformed and malpositioned. It is estimated that the earliest occurrences of arrested eruption of primary molars supposedly occur before the age of 3. [source] Hunter-Schreger Band patterns in human tooth enamelJOURNAL OF ANATOMY, Issue 2 2010Christopher D. Lynch Abstract Using light microscopy, we examined Hunter-Schreger Band (HSB) patterns on the axial and occlusal/incisal surfaces of 160 human teeth, sectioned in both the buccolingual and mesiodistal planes. We found regional variations in HSB packing densities (number of HSBs per mm of amelodentinal junction length) and patterns throughout the crown of each class of tooth (maxillary and mandibular: incisor, canine, premolar, and molar) examined. HSB packing densities were greatest in areas where functional and occlusal loads are greatest, such as the occlusal surfaces of posterior teeth and the incisal regions of incisors and canines. From this it is possible to infer that the behaviour of ameloblasts forming enamel prisms during amelogenesis is guided by genetic/evolutionary controls that act to increase the fracture and wear resistance of human tooth enamel. It is suggested that HSB packing densities and patterns are important in modern clinical dental treatments, such as the bonding of adhesive restorations to enamel, and in the development of conditions, such as abfraction and cracked tooth syndrome. [source] Effect of enamel matrix proteins (Emdogain®) on healing after re-implantation of "periodontally compromised" rootsJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 10 2003An experimental study in the dog Abstract Objective: The present experiment was performed to assess whether Emdogain® applied on the root surface of extracted teeth or teeth previously exposed to root planning can protect the tooth from ankylosis following re-implantation. Material and Methods: The experiment included two groups of dogs, including five animals each. The root canals of all mandibular third premolars (3 P 3) were reamed and filled with gutta-percha. A crestal incision was placed from the area of the second to the fourth premolar. Buccal and lingual full thickness flaps were elevated. With the use of a fissure bur, the crown and furcation area of 3 P 3 were severed in an apico-coronal cut. The distal and mesial tooth segments were luxated with an elevator and extracted with forceps. Group A: The mesial and distal segments of 3 P 3 were air dried on a glass surface for 60 min. The roots from the right side were conditioned and exposed to Emdogain® application. The roots from the left side received the same treatment with the exception of Emdogain® application. The mesial and distal tooth segments were re-implanted and the crown portions were severed with a horizontal cut and removed. The buccal and lingual flaps were mobilized and sutured to obtain complete coverage of the submerged roots. Group B: A notch was prepared in each root, 4,5 mm apical of the cemento-enamel junction. The area of the root that was located coronal to the notch was scaled and planned. The roots in the right side of the mandible were treated with Emdogain®, while the roots in the left side served as controls. After 6 months of healing, the dogs were killed and blocks containing one root with surrounding tissues were harvested, and prepared for histological examination, which also included morphometric assessments. Thus, the proportions of the roots that exhibited signs of (i) replacement (ii) inflammatory and (iii) surface resorption were calculated. Results and Conclusion: It was demonstrated that healing of a re-implanted root that had been extracted and deprived of vital cementoblasts was characterized by processes that included root resorption, ankylosis and new attachment formation. It was also demonstrated that Emdogain® treatment, i.e. conditioning with EDTA and placement of enamel matrix proteins on the detached root surface, failed to interfere with the healing process. Zusammenfassung Zielsetzung: Untersuchung, ob Emdogain®, wenn es auf die Wurzeloberfläche extrahierter Zähne oder von Zähnen, die zuvor eine Wurzelglättung bekommen haben, appliziert wird, die Zähne nach Reimplantation vor Ankylose schützen kann. Material und Methoden: Die Studie wurde bei 2 Gruppen von Hunden durchgeführt, die je 5 Tiere umfasste. Die Wurzelkanäle aller 3. Prämolaren des Unterkiefers (3 P 3) wurden aufbereitet und mit Guttapercha gefüllt. Ein Schnitt auf dem Limbus alveolaris wurde vom 2. zum 4 Prämolaren geführt. Bukkal und lingual wurde ein Vollschichtlappen mobilisiert. Mit einem Fissurenbohrer wurden die 3 P 3 mit einem Schnitt in koronoapikaler Richtung im Bereich der Krone und der Furkation geteilt. Die distalen und mesialen Zahnsegmente wurden mit einem Elevator luxiert und mit einer Zange extrahiert. Gruppe A: Die mesialen und distalen Segmente von 3 P 3 wurden auf einer Glasoberfläche 60 min lang luftgetrocknet. Die Wurzeln der rechten Seite wurden konditioniert und mit Emdogain® beschickt. Die Wurzeln der linken Seite erhielten die gleiche Behandlung mit der Ausnahme, dass keine Applikation von Emdogain® erfolgte. Die mesialen und distalen Wurzeln wurden reimplantiert und die Kronenanteile durch einen horizontalen Schnitt getrennt und entfernt. Die bukkalen und lingualen Lappen wurden mobilisiert und durch Naht ein vollständiger Verschluss der reimplantierten Wurzeln erreicht. Gruppe B: In jede Wurzel wurde 4,5 mm apikal der Schmelz-Zement-Grenze eine Kerbe präpariert. Der Bereich der Wurzel, der koronal dieser Kerbe lag, wurde gescalt und wurzelgeglättet. Die Wurzeln der rechten Unterkieferseite wurden mit Emdogain® behandelt, während die Wurzeln der linken Seite als Kontrolle dienten. Nach einer Heilung von 6 Monaten wurden die Hunde getötet und Blöcke, die eine Wurzel und das umgebende Gewebe enthielten, gewonnen und für die histologische Untersuchung präpariert, die auch morphometrische Befunde einschloss. Es wurden also die Anteile der Wurzeln berechnet, die Zeichen von (i) Ersatz- (ii) entzündlicher und (iii) Oberflächenresorption zeigten. Ergebnisse und Schlussfolgerungen: Es wurde gezeigt, dass die Heilung von reimplantierten Wurzeln, die extrahiert und von vitalen Zementoblasten befreit worden waren, durch Prozesse charakterisiert war, die Wurzelresorption, Ankylose und die Bildung neuen Attachments umfassten. Es wurde gezeigt, dass die Behandlung mit Emdogain®, d.h. Konditionierung mit EDTA und Applikation des Schmelz-Matrix-Proteins auf die freie Wurzeloberfläche diesen Heilungsprozess nicht beeinflussen konnte. Résumé Objectif: Cette expérimentation fut réalisée pour déterminer si Emdogain® appliqué sur la surface radiculaire de dents extraites ou de dents préalablement soumises à un surfaçage radiculaire pouvait protéger la dent de l'ankylose après réimplantation. Matériel et Méthodes: L'expérience comprenait 2 groupes de 5 chiens. Les canaux radiculaires de toutes les troisièmes premolaires mandibulaires (3 P 3) furent alésés et bouchés à la gutta-percha. Une incision crestale de la deuxième à la quatrième prémolaire permit de soulever un lambeau de pleine épaisseur vestibulaire et lingual. La couronne et la zone de furcation de 3 P 3 furent découpées à l'aide d'une fraise fissure d'apical en coronaire. Les segments distaux et mésiaux furent luxés avec un élévateur et extraits avec un davier. Groupe A: Les segments mésiaux et distaux de 3 P 3 furent séchés à l'air sur une plaque de verre pendant 60 min. Les racines du coté droit furent préparées et imprégnées d' Emdogain®. Les racines gauches reçurent le même traitement sans application d'Emdogain ®. Les segments mésiaux et distaux furent alors réimplantés et les couronnes découpées par un trait horizontal et éliminées. Les lambeaux vestibulaires et linguaux furent déplacés et suturés pour obtenir un recouvrement complet des racines enfouies. Groupe B: Une entaille a été préparée sur chaque racine, à 4,5 mm en apical de la jonction amélo-cémentaire. La surface de racine située coronairement à cette entaille fut alors détartrée et surfacée. Les racines du coté droit furent traitées par Emdogain® alors que les racines du coté gauche firent office de contrôle. Après 6 mois de cicatrisation, les chiens furent sacrifiés et des blocs contenant une racine et les tissus environnant furent prélevés pour un examen histologique et morphométrique. Ainsi, les proportions de racine présentant des signes de (i) remplacement (ii) d'inflammation et (iii) de résorption furent calculées. Résultats et conclusion: Nous avons démontré que la cicatrisation de racine réimplantées après extraction et élimination des cémentoblastes se caractérisait par un processus qui comprenait résorption radiculaire, ankylose et formation d'une nouvelle attache. Nous avons aussi démontré que le traitement par Emdogain®, c'est à dire conditionnement à l'EDTA et mise en place de protéines de la matrice améllaire sur la surface radiculaire, ne pouvait pas interférer avec le processus de cicatrisation. [source] Generalized cervical root resorption associated with periodontal diseaseJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 11 2001Wouter Beertsen Abstract Background and description of case: The etiology and pathogenesis of generalized cervical root resorptions is not well understood. In the present report, a case of severe cervical root resorption involving 24 anterior and posterior teeth is presented. The lesions developed within a period of 2 years after the patient had changed to an acid-enriched diet. They extended far into the coronal dentin and were associated with gingival inflammation and crestal bone resorption. However, no generalized clinical attachment loss had occurred. Culturing of subgingival plaque revealed the presence of several putative periodontal pathogens among which Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis. Treatment consisted of mechanical debridement supported by systemic antibiotics (amoxycillin plus metronidazole) and dietary advice. Results: Within 1 year after the onset of treatment, all resorptive lesions had repaired by ingrowth of a radio-opaque mineralized tissue. The crestal areas showed radiological evidence of bone repair. 3 years after the onset of therapy, one premolar was extracted and examined histologically. It appeared that irregularly-shaped masses of woven bone-like tissue had invaded into the domain of the resorbed coronal dentin and were bordered by thin layers of acellular cementum. Conclusion: It is concluded that, in this patient, the cervical resorptions were likely the result of an osteoclastic response extending into the roots because the root-protective role of the junctional epithelium did not develop. We hypothesize that this was due to the combined effects of a periodontopathogenic microflora and a dietary confounding factor. Zusammenfassung Hintergrund und Beschreibung des Falls: Die Ätiologie und die Pathogenese der generalisierten Wurzelresorptionen ist nicht besonders bekannt. In der vorliegenden Fallpräsentation wird ein schwerer Fall von Wurzelresorption gezeigt, die 24 anteriore und posteriore Zähne einbezog. Die Läsionen entwickelten sich innerhalb einer Periode von 2 Jahren, nachdem der Patient zu einer Säure-angereicherten Diät gewechselt hatte. Die Läsionen dehnten sich in das koronale Dentin aus und waren mit gingivaler Entzündung und krestaler Knochenresorption verbunden. Jedoch wurde kein generalisierter Attachmentverlust beobachtet. Die Kultur der subgingivalen Plaque erbrachte das Vorhandensein von verschiedenen putativen parodontalen Pathogenen, unter ihnen Actinobacillus actinomycetemcomitans und Porphyromonas gingivalis. Die Behandlung bestand in der mechanischen Reinigung unterstützt mit systemischen Antibiotika (Amoxicillin und Metronidazol) und Diätanweisungen. Ergebnisse: Innerhalb eines Jahres nach dem Beginn der Therapie waren alle Resorptionsläsionen repariert durch das Einwachsen von röntgenopakem mineralisierten Gewebe. Die krestalen Regionen zeigten radiologisch nachgewiesene Knochenreparatur. 3 Jahre nach Therapiebeginn wurde ein Prämolar extrahiert und histologisch untersucht. Es schien, daß irreguläre geformte Massen von verflochtenem knochen-ähnlichen Gewebe in den Hauptteil des resorbierten koronalen Dentins hineingelangt sind und von dünnen Schichten azellulären Zementes begrenzt wurden. Zusammenfassung: Es wird geschlußfolgert, daß bei diesem Patient die zervikalen Resorptionen wahrscheinlich das Ergebnis einer osteoklastischen Reaktion waren, bis in die Wurzeln ausgedehnt, weil sich die wurzelschützende Rolle des Verbindungsepithels nich entwickelt hatte. Wir nehmen an, daß dies in der Folge eines kombinierten Effektes von parodontopathogenen Keimen und eines verwirrenden diätetischen Faktors geschah. Résumé Origine: L'étiologie et la pathogenèse des résorptions radiculaires cervicales généralisées ne sont pas suffisamment connues. Dans le rapport présent, un cas de résorption radiculaire cervicale sévère se rapportant à 24 dents antérieures et postérieures est présenté. Les lésions s'étaint développées durant les 2 années qui ont suivi le changement de régime alimentaire du patient vers un régime plus acide. Elles s'étendaient profondément dans la dentine coronaire et étaient associées à une inflammation gingivale et une résorption osseuse crestale. Cependant, aucune perte d'attache clinique généralisée n'est apparue. La culture de la plaque dentaire sous-gingivale a révélé la présence de plusieurs pathogènes parodontaux putatifs parmi lesquels l'Actinobaccilus actinomycetemcomitans et le Porphyromonas gingivalis. Le traitement a consisté en un nettoyage mécanique associéà l'utilisation d'antibiotiques par voie systémique (amoxycilline + métronidazole) et un conseil diététique. Résultats. Dans l'année qui a suivi ce traitement, toutes les lésions de résorption ont été guéries par la croissance d'un tissu minéralisé radio-opaque. Les zones crestales montraient une évidence radiologique de réparation osseuse. 3 ans après le démarrage de ce traitement, une prémolaire a été avulsée et examinée histologiquement. Il est apparu que des masses de formes irrégulières de tissus ressemblant à de l'os ouaté avaient envahi le domaine de dentine coronaire résorbé et étaient entourées par de fines couches de cément acellulaire. Conclusions: Chez ce patient, les résorptions cervicales étaient vraisemblablement dûes à une réponse ostéoclastique s'étendant dans les racines parce que le rôle de protection radiculaire de l'épithélium de jonction ne s'étaient pas développé. Cette situation était vraisemblablement dûe à des effets combinés de la microflore parodonto-pathogène et d'un facteur diététique. [source] Myxoid liposarcoma of the oral cavity with involvement of the periodontal tissuesJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2 2001Gianfranco Favia Abstract Background, aims: Liposarcoma is the 2nd most frequent soft tissue sarcoma in adults, but it is extremely rare in the head and neck and, particularly, in the oral cavity. We report on a 25-year-old female who presented with a periodontal mass, extended from the right upper 3rd molar to the right upper 2nd premolar, covered by intact oral mucosa. The clinical differential diagnosis included peripheral giant cell granuloma, salivary gland neoplasms, squamous cell carcinoma of the gingiva, sarcoma and malignant lymphoma. Methods: To accurately plan subsequent treatment, an excisional biopsy was performed and a myxoid liposarcoma was diagnosed. Consequently, the patient underwent wide excision of the neoplasm with maxillary en-block resection. Results: The post-operative course was uneventful and the patient is alive and well 8 years after the original diagnosis. The authors stress the importance of considering soft tissue sarcomas in the diagnostic approach to patients with unusual periodontal neoplasms and to plan adequate surgical sampling of the lesion (i.e. excisional biospy). Conclusions: This appears of pivotal importance as more limited specimens may result in inaccurate pre-operative diagnosis. [source] Orthodontic movement in bone defects augmented with Bio-Oss®JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 1 2001An experimental study in dogs Abstract Objective: To study if it was possible to move, by orthodontic means, a tooth into an area of the jaw that had been augmented with Bio-Oss®. Material and Methods: 5 beagle dogs were used. The 1st, 2nd, and 4th mandibular premolars on each side were removed. The defect at the left 4th premolar site was filled with a biomaterial (Bio-Oss®) while the corresponding defect in the right side was left for spontaneous healing. 3 months later, an orthodontic device was inserted in each side of the mandible. The device was designed to allow distal, bodily movement of the 3rd premolars. When the experimental teeth had been moved into the extraction sites of the 4th premolars, the animals were sacrificed and biopsies of the premolar-molar regions of the mandible sampled. The tissues were prepared for histological analysis using standard procedures. In the sections, 3 zones were identified: zone A=the bone tissue within the distal portion of the previous extraction site (4th premolar), zone B=the pressure side of the 3rd premolar, zone C=the tension side of the 3rd premolar. The area occupied by mineralized bone, Bio-Oss® particles and bone marrow was determined by a point counting procedure. The width of the periodontal ligament as well as the percentage of the root surface (in zone B) that exhibited resorption was determined. Results: The findings demonstrated that it was possible to move a tooth into an area of an alveolar ridge that 3 months previously had been augmented with a biomaterial. It was also demonstrated that 12 months after grafting, Bio-Oss® particles remained as inactive filler material in the not utilized part of zone A. The biomaterial was not present in zone C but present in small amounts in zone B. Conclusion: During the orthodontic tooth movement the graft material (Bio-Oss®) was degraded and eliminated from the part of the alveolar ridge that was utilized for the experiment. In the non-utilized part of the ridge the biomaterial, however, remained as a seemingly inactive filler material. [source] Clinical evaluation of Procera AllCeram crowns in Japanese patients: results after 5 yearsJOURNAL OF ORAL REHABILITATION, Issue 11 2009Y. KOKUBO Summary, Procera AllCeram crowns were prospectively evaluated clinically in both anterior and posterior regions in Japanese. One-hundred and one crowns were fabricated for 57 patients at the Tsurumi University Dental Hospital from August 2001 to October 2002 and evaluated according to the California Dental Association (CDA) quality evaluation system at baseline and annually at all follow-up examinations for 5 years. The plaque index (PI) and gingival index (GI) were recorded, and chipping and fracture were checked at the same time as well. A total of 75 Procera AllCeram crowns were evaluated, and the cumulative survival rate was 90·2% over the 5-year clinical trial. Six crowns experienced fractures within the veneering porcelain and from aluminium oxide coping, all of which occurred on the premolar and molar regions, and they had to be removed. Small chipping was observed on three crowns. According to the CDA criteria, 98% of Procera AllCeram crowns were rated as satisfactory, and PI and GI were comparable to those of control teeth during the observation period. [source] Age and gender-related differences in premolar and molar functional areasJOURNAL OF ORAL REHABILITATION, Issue 4 2007P. BOURDIOL summary, The aim of the present study was to underline the difference in premolar,molar functional areas according to both age and gender in a human adult population. Premolar and molar series were marked manually on opposed casts with articulating paper and functional areas were evaluated by quantification of these markings. It was noticed that on average larger functional areas were displayed by the older group (19 individuals, mean age 71·2 years, minimum 68 years, maximum 73 years) in comparison with the younger one (24 individuals, mean age 27·4 years, minimum 22 years; maximum 33 years). It was also observed that the average total functional area (4 hemiarches) was larger in the male subgroup (n: 23; mean age 45; young adults, 14; old adults, 9) compared with the female one (n: 20; mean age 49; young adults, 10; old adults, 10). Nevertheless, this gender difference in premolar,molar functional areas was related to the individual occlusal areas. As a matter of fact, when the individual occlusal area was taken into account for each series in the form of a ratio (functional area/occlusal area), the values obtained were not different between both gender subgroups studied. When comparing premolar and molar functional ratios (functional area/occlusal area) between age groups, it appears that the values obtained were slightly higher for the premolar series (ratios for young and older adults, respectively: Premolar series: 23·6 ± 7·5%, 30 ± 6·5%; Molar series: 23·1 ± 6·8%, 27·3 ± 6·7%). This difference was interpreted in relation to the reference (occlusal area) chosen. [source] Relationship between tooth contacts in the retruded contact position and mandibular positioning during retrusionJOURNAL OF ORAL REHABILITATION, Issue 11 2006S. YAMASHITA summary, We conducted a series of studies with the purpose to investigate the locations of tooth contacts in the retruded contact position (RCP) and to discuss their significance in the stomatognathic system. In the present study, the relationship between the locations of RCP contacts and mandibular positioning during retrusion was examined. Thirty dentists and clinical residents were selected as subjects. One specialist in prosthetic dentistry examined each subject for the location of the RCP contacts. The mandibular positioning during retrusion was measured using a mandibular movement analysis system with six degrees of freedom. Originally programmed software was developed. Five reference points were selected: the central lower incisor (point I), the first molars on both sides (points RM and LM) and the condyles on both sides (points RC and LC). Tooth contact was observed most frequently at the second molar, followed by the first premolar. Points I, RM and LM all moved in an inferior-posterior direction, whereas points RC and LC moved in various directions ranging from superior-posterior to inferior-posterior. When the subjects were divided into two groups according to the most anterior tooth of occlusion in the RCP, the condylar positioning tended to be more superior in the group with molar contact than that with premolar contact. These results suggest that the locations of RCP contacts could be an important factor in jaw guidance during retrusion. [source] The effect of retainer thickness on posterior resin-banded prostheses: a finite element studyJOURNAL OF ORAL REHABILITATION, Issue 11 2004T.-S. Lin summary, According to its design concept, a resin-bonded prosthesis, compared with the conventional fixed partial denture, is a weak and unstable structure. Therefore, a resin-bonded prosthesis induces a higher failure rate, especially in the posterior region. Recently, adhesion agents have been profoundly improved. However, the design guidelines of posterior resin-bonded prostheses (RBP) have seldom been evaluated from a biomechanical perspective. The objective of this study was to investigate the biomechanical effects of the retainer thickness on posterior RBP using the finite element method. A solid model of a posterior mandibular resin-bonded prosthesis, which employed the second molar and second premolar as the abutment teeth, was constructed and meshed with various retainer thickness (ranging from 0·2 to 1·0 mm). Horizontal and vertical loadings of 200 N were applied respectively at the central fossa of the pontic to examine the stress level at the interface between the retainer and abutment teeth. All exterior nodes in the root, below the cementoenamel junction were fixed as the boundary condition. The results showed that horizontal loading would induce higher interfacial stresses than the vertical loading which indicated that the horizontal component of the occlusal force plays a more important role in evaluating the debonding phenomenon. Further, the peak interfacial stresses increased as the retainer thickness decreased and, based on the fitted relation between retainer thickness and interfacial stresses, a 0·4 mm retainer thickness was suggested as the minimum required to prevent severe interfacial stresses increasing. [source] Investigation of the factors related to the formation of the buccal mucosa ridgingJOURNAL OF ORAL REHABILITATION, Issue 6 2003I. Takagi summary, The aim of this study was to clarify the factors related to the formation of the buccal mucosa ridging, which has been mentioned to be a clinical sign of clenching. Twenty-one individuals were investigated and divided into three groups: (i) those without buccal mucosa ridging, (ii) the buccal mucosa ridging located in all the posterior teeth region, and (iii) the buccal mucosa ridging corresponding only to the molar teeth region. A pressure sensor was used and placed at two points: first upper premolar and second upper molar. The recording tasks were: (i) silent reading at rest, (ii) light voluntary clenching, (iii) maximum voluntary clenching, (iv) holding the cheeks tightly against the teeth while light voluntary clenching, (v) holding the cheeks tightly against the teeth without tooth contact, (vi) pulling angle of mouth laterally while light voluntary clenching, (vii) pulling angle of mouth laterally without tooth contact and (viii) swallowing. No significant differences were found between groups in all the recording tasks except for the swallowing, at which significant difference (P < 0·05) was found between the groups of individuals having buccal mucosa ridging and without it. Based on these results it became clear that the buccal mucosa pressure exerted on the buccal aspect of teeth during swallowing plays an important role in the formation of buccal mucosa ridging. [source] Influence of working side contacts on masticatory function for mandibular distal extension removable partial denturesJOURNAL OF ORAL REHABILITATION, Issue 3 2003S. Sueda summary The aim of this study was to clarify the influence of working side contacts for masticatory function for a distal extension removable partial denture. Five subjects who had edentulous arches from second premolar to second molar opposing natural teeth participated. Working side contacts were altered by using three types of artificial teeth attached to the denture base. A-form teeth made contact with opposite teeth while acting as the working side in a lateral excursion. The cusp angles of B- and C-form teeth were decreased by 10° and 20°, respectively compared with A-form teeth. B-and C-form teeth discluded with opposite teeth on the working side. Subjects were asked to perform two kinds of masticatory performance test. Obtained data were evaluated by the repeated-measures anova and the Tukey test for multiple comparisons. Results revealed that there was a significant difference (P=0·001) in the three types of teeth in the mixing ability test and the value of A-form teeth was statistically less value than those of the other teeth. However, there was no significant difference in the comminuting ability test. These results suggested that working side contacts between artificial teeth and opposite natural teeth influenced mixing ability, but not comminuting ability. [source] The effect of interfacial failure around a class V composite restoration analysed by the finite element methodJOURNAL OF ORAL REHABILITATION, Issue 2 2000J. S. Rees Partial failure around the tooth,composite interface of a class V restoration is common due to the effects of polymerization shrinkage. The effect that this has on the force distribution of the remaining intact interfaces has not been investigated. The aim of this study was to quantify the effect that partial failure of an isolated cavity wall interface had on the force distribution around the remaining intact interfaces of a class V composite restoration in a lower first premolar using a two-dimensional plane strain finite element model. Partial failure resulted in a 4,6-fold increase in peak tensile and shear forces compared to a tooth with a fully intact cavity wall interface. In some instances, the peak stresses were greater than the known bond strengths of composite to dentine. [source] The Effect of a Constant Electrical Field on Osseointegration after Immediate Implantation in Dog Mandibles: A Preliminary StudyJOURNAL OF PROSTHODONTICS, Issue 5 2007Yadollah Soleymani Shayesteh DDS Purpose: The long time span between insertion of implants and functional rehabilitation often inconveniences patients. Accelerating bone growth around dental implants can shorten this time span. This in vivo study evaluated the effect of a constant electrical field on bone growth around dental implants. Materials and Methods: Four mongrel dogs were used in this study. Sixteen dental implants were placed immediately after extraction of the first premolar and molar teeth. A constant electrical field (CEF) generator was placed in the mucoperiostal pouch created from the subperiostral dissection under the inferior border of the dog's mandible and connected to the experiment side fixtures. CEF provided 3 V of electrical potential during osseointegration. Histologic sections were stained with hematoxylin,eosin and observed under light microscopy. The sections were analyzed histomorphometrically to calculate the amount of newly formed bone. Statistical analysis was performed with SPSS 11.0 computer software (,= 0.05). Results: At the end of the first stage of the osseointegration (90 days) CEF group sections showed enhanced growth of the trabeculae compared with the control group. Statistical analysis revealed significant differences between experimental and control groups. Bone contact ratio was statistically significant in the experimental group (p= 0.001). An increase in the local bone formation and bone contact ratio was observed with direct electrical stimulation of the implant and the bone area around the implant. Conclusion: Minimal direct electrical current, which can produce an electrical field around the implant, can increase the amount of bone formation and decrease the time of osseointegration. [source] Tooth Preparation: A Study on the Effect of Different Variables and a Comparison Between Conventional and Channeled Diamond BursJOURNAL OF PROSTHODONTICS, Issue 1 2004Daniel F. Galindo DDS Purpose: The purpose of this study was to evaluate the different variables involved in tooth cutting to characterize intrapulpal temperature generation, cutting efficiency, and bur durability when using conventional and channeled diamond burs. Materials and Methods: Forty premolars and 60 molars were selected for the study. Four diamond burs were paired according to grit size: 125- ,m grit: Brasseler Coarse (Control 1) and TDA System (Test 1) burs; and 180- ,m grit: Brasseler CRF (Control 2) and NTI Turbo Diamond (Test 2) burs. Each bur was used twice when cutting the premolar teeth, whereas it was used for 60 cuts when cutting the molar teeth. The data were analyzed to compare the correlation of bur design, grit and wear, amount of pressure, advancement rate, revolutions per minute, cutting time and rate, and proximity to the pulp chamber with intrapulpal temperature generation, cutting efficiency, and bur longevity. The mean values of test and control burs in each group were compared using an ANOVA (p < 0.05 for significant differences) for temperature generation and an ANOVA and the Tukey multiple range test (p, 0.05) for cutting efficiency and bur longevity. Results: No significant difference was found in intrapulpal temperature generation while cutting premolar and molar teeth with conventional and channeled diamond burs. In both groups, the mean temperature recorded during and after the cutting procedure was lower than the baseline temperature. For premolar teeth, no significant difference was established for control and test burs for the load required to cut into the tooth and the cutting rate. However, both test burs showed significantly fewer revolutions per minute when compared to their control counterparts. For the molar teeth, the Brasseler CRF bur required a significantly lower cutting load when compared to the NTI bur, whereas no difference was noted between the other pair of burs. The cutting rate was significantly higher for both control burs, whereas revolutions per minute (rpm) were greater for control coarser burs only. Overall, channeled burs showed a significantly lower cutting efficiency when compared to conventionally designed burs. Conclusion: Within the limitations of this study, channeled burs showed no significant advantage over conventional diamond burs when evaluating temperature generation and bur durability. Moreover, the cutting efficiency of conventional burs was greater than that of channeled burs. [source] A rapid screening technique for feline odontoclastic resorptive lesionsJOURNAL OF SMALL ANIMAL PRACTICE, Issue 12 2004M. Heaton The feline odontoclastic resorptive lesion (FORL) status (presence or absence of odontoclastic resorptive lesions) of 423 clinically healthy cats was determined based on radiographic findings in a series of full mouth radiographs (eight views). This status was compared with the FORL status based on evaluation of only two views, namely the right and left mandibular premolar and molar views. Using the FORL status of the right and left third mandibular premolars (307 and 407) alone correctly predicted overall FORL status in 93·4 per cent of cats. The sensitivity of the new technique (FORL cases correctly diagnosed as positive by the test) was 78·5 per cent, while the negative predictive value (negative FORL cases correctly diagnosed by the test) was 91·3 per cent. Overall FORL status can therefore be confidently diagnosed in nine out of 10 cats by assessing FORL status in just two teeth (307 and 407) using two films, which has benefits for the cat (less anaesthetic time and reduced exposure to radiation) and the owner (reduced cost of screening). [source] Orthodontic brackets removal under shear and tensile bond strength resistance tests , a comparative test between light sourcesLASER PHYSICS LETTERS, Issue 3 2008P.C.G. Silva Abstract We have investigated if a new LEDs system has enough efficient energy to promote efficient shear and tensile bonding strength resistance under standardized tests. LEDs 470 ± 10 nm can be used to photocure composite during bracket fixation. Advantages considering resistance to tensile and shear bonding strength when these systems were used are necessary to justify their clinical use. Forty eight human extracted premolars teeth and two light sources were selected, one halogen lamp and a LEDs system. Brackets for premolar were bonded through composite resin. Samples were submitted to standardized tests. A comparison between used sources under shear bonding strength test, obtained similar results; however, tensile bonding test showed distinct results: a statistical difference at a level of 1% between exposure times (40 and 60 seconds) and even to an interaction between light source and exposure time. The best result was obtained with halogen lamp use by 60 seconds, even during re-bonding; however LEDs system can be used for bonding and re-bonding brackets if power density could be increased. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] | ||||||||||||||||||||||||||||||||||||||||