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Fourth Premolars (fourth + premolar)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

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 tissues

INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 2 2010
T. 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]

Effect of enamel matrix proteins (Emdogain®) on healing after re-implantation of "periodontally compromised" roots

JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 10 2003
An 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]

The critical-size supraalveolar peri-implant defect model: characteristics and use

JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 11 2006
Ulf M. E. Wikesjö
Abstract Objective: Novel implant technologies and reconstructive therapies for alveolar augmentation require pre-clinical evaluation to estimate their biologic potential, efficacy, and safety before clinical application. The objective of this report is to present characteristics and use of the critical-size, supraalveolar, peri-implant defect model. Methods: Bilateral extraction of the mandibular premolars was performed in 12 Hound Labrador mongrel dogs following horizontal surgical cut-down of the alveolar ridge approximating 6 mm. Each jaw quadrant received three custom-produced TiUniteÔ, ,4.0 × 10 mm threaded implants placed into osteotomies prepared into the extraction sites of the third and fourth premolars. The implants exhibited a reference notch 5 mm from the implant platform to facilitate surgical placement leaving 5 mm of the implant in a supraalveolar position, and to serve as a reference point in the radiographic, histologic and histometric analysis. The implants were submerged under the mucoperiosteal flaps for primary intention healing. Fluorescent bone markers were administered at weeks 3 and 4 post-surgery, and pre-euthanasia. The animals were euthanized following an 8-week healing interval when block biopsies were collected for analysis. Results: Healing was generally uneventful. The radiographic and histometric evaluations demonstrate the limited osteogenic potential of this defect model. Whereas lingual peri-implant sites exhibited a mean (±SE) bone gain of 0.4±0.1 mm, resorption of the buccal crestal plate resulted in a mean bone loss of 0.4±0.2 mm for an overall osteogenic potential following sham-surgery averaging 0.0±0.1 mm. Overall bone density and bone,implant contact in the contiguous resident bone averaged 79.1±1.1% and 76.9±2.3%, respectively. Conclusion: The results suggest that the critical-size, supraalveolar, peri-implant defect model appears a rigorous tool in the evaluation of candidate technologies for alveolar reconstruction and osseointegration of endosseous oral implants. Limited innate osteogenic potential allows critical evaluation of osteogenic, osteoconductive, or osteoinductive technologies in a challenging clinical setting. [source]

Low-intensity pulsed ultrasound accelerates periodontal wound healing after flap surgery

JOURNAL OF PERIODONTAL RESEARCH, Issue 2 2008
H. Ikai
Background and Objective:, A study was conducted to evaluate the effects of low-intensity pulsed ultrasound on wound healing in periodontal tissues after mucoperiosteal flap surgery. Material and Methods:, Bony defects were surgically produced bilaterally at the mesial roots of the mandibular fourth premolars in four beagle dogs. The flaps were repositioned to cover the defects and sutured after scaling and planing of the root surface to remove cementum. The affected area in the experimental group was exposed to low-intensity pulsed ultrasound, daily for 20 min, for a period of 4 wk from postoperative day 1 using a probe, 13 mm in diameter. On the control side, no ultrasound was emitted from the probe placed contralaterally. After the experiment, tissue samples were dissected out and fixed in 10% formalin for histological and immunohistochemical analyses. Results:, The experimental group showed that the processes in regeneration of both cementum and mandibular bone were accelerated by low-intensity pulsed ultrasound compared with the control group. In addition, the expression level of heat shock protein 70 was higher in the gingival epithelial cells of the low-intensity pulsed ultrasound-treated tooth. Conclusion:, Our results suggest that osteoblasts, as well as cells in periodontal ligament and gingival epithelium, respond to mechanical stress loaded by low-intensity pulsed ultrasound, and that ultrasound accelerates periodontal wound healing and bone repair. [source]

Tissue modeling following implant placement in fresh extraction sockets

CLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2006
Mauricio G. Araújo
Abstract Objective: To study whether osseointegration once established following implant placement in a fresh extraction socket may be lost as a result of tissue modeling. Material and methods: Seven beagle dogs were used. The third and fourth premolars in both quadrants of the mandible were used as experimental teeth. Buccal and lingual full-thickness flaps were elevated and distal roots were removed. Implants were installed in the fresh extraction socket. Semi-submerged healing of the implant sites was allowed. In five dogs, the experimental procedure was first performed in the right side of the mandible and 2 months later in the left mandible. These five animals were sacrificed 1 month after the final implant installation. In two dogs, the premolar sites on both sides of the mandible were treated in one surgical session and biopsies were obtained immediately after implant placement. All biopsies were processed for ground sectioning and stained. Results: The void that existed between the implant and the socket walls at surgery was filled at 4 weeks with woven bone that made contact with the SLA surface. In this interval, (i) the buccal and lingual bone walls underwent marked surface resorption and (ii) the height of the thin buccal hard tissue wall was reduced. The process of healing continued, and the buccal bone crest shifted further in the apical direction. After 12 weeks, the buccal crest was located>2 mm apical of the marginal border of the SLA surface. Conclusion: The bone-to-implant contact that was established during the early phase of socket healing following implant installation was in part lost when the buccal bone wall underwent continued resorption. [source]