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Mandibular Premolars (mandibular + premolar)
Terms modified by Mandibular Premolars Selected AbstractsA 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] Mandibular first premolar with two roots and three canalsAUSTRALIAN ENDODONTIC JOURNAL, Issue 1 2010Saravanan Poorni bds Abstract This case report presents a relatively uncommon clinical case of a mandibular premolar with two roots and three canals. The possibility of additional root canals should be considered even in teeth with a low frequency of abnormal root canal anatomy. Sound knowledge of root canal anatomy, appropriate assessment of the pulp chamber floor, critical interpretation of radiographs and high-magnification examinations are highly desirable to achieve the best possible outcome in complicated root canal therapy. [source] Pulp revascularization of necrotic bilateral bicuspids using a modified novel technique to eliminate potential coronal discolouration: a case reportINTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2009K. Reynolds Abstract Aim, To present a case report in which the pulp of two bilateral mandibular premolars with dens evaginatus were revascularized using a modified novel technique to avoid undesired crown discolouration. Summary, Recently, regeneration of necrotic pulps has become an alternative conservative treatment option for young permanent teeth with immature roots and is a subject of great interest in the field of endodontics. This novel procedure exploits the full potential of the pulp for dentine deposition and produces a stronger mature root that is better able to withstand the forces than can result in fracture. However, the current protocol has potential clinical and biological complications. Amongst them, crown discolouration, development of resistant bacterial strains and allergic reaction to the intracanal medication. In the case presented, a modified technique to avoid undesired crown discolouration was applied sealing the dentinal tubules of the chamber, thus avoiding any contact between the tri-antibiotic paste and the dentinal walls. Key learning points, ,,Sealing the dentinal tubules of the chamber prevents the undesirable crown discolouration produced by tri-antibiotic medication whilst maintaining the revascularization potential of the pulp. ,,Further research is warranted to seek an alternative infection control protocol capable of preventing possible allergic reactions and development of resistant strains of bacteria, as well as a biological material capable of inducing angiogenesis and allow a more predictable scaffold and tissue regeneration. [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] Periapical radiographs overestimate root canal wall thickness during post space preparationINTERNATIONAL ENDODONTIC JOURNAL, Issue 8 2008E. M. Souza Abstract Aim, To evaluate differences between anatomic and radiographic measurements of root canal wall thickness (RCWT) after each root canal preparation stage during post placement. Methodology, Twenty mandibular premolars with a single canal were decoronated and the roots embedded in resin using a teflon muffle. Roots were sectioned horizontally at a pre-established level and canals were prepared for post placement. Endodontic hand files were used for root canal preparation, followed by Gates Glidden drills and Peeso reamers. Standardized radiographs and photographs at pre-established measurement levels were taken before preparation, after root canal instrumentation, after Gates Glidden preparation and after Peeso enlargement. All images were digitized and RCWT at the mesial and distal walls measured (imagetool 3.0). Differences between radiographic and anatomic measurements were analysed with paired t- tests. anova was used to compare the percentages of radiographic distortions. Results, Regardless of the time-point evaluated, RCWT determined by radiographs were greater than the respective anatomic measurements (P < 0.05). The difference detected at each stage was similar and constant (P > 0.05). Conclusions, Throughout preparation for post placement, radiographic images overestimated the RCWT by approximately 25%, regardless of the clinical stage evaluated. [source] Effectiveness in cleaning oval-shaped root canals using Anatomic Endodontic Technology, ProFile and manual instrumentation: a scanning electron microscopic studyINTERNATIONAL ENDODONTIC JOURNAL, Issue 6 2005O. Zmener Abstract Aim, To compare in vitro the cleanliness of root canal walls in oval-shaped root canals following automated or manual instrumentation. Methodology, Forty-five oval-shaped single-rooted maxillary and mandibular premolars with straight canals were divided into three groups of 15. Automated canal preparation was performed using Anatomic Endodontic Technology (AET, group 1) and the ProFile system (group 2). Manual instrumentation (group 3) was performed with K-Flexofiles. Irrigation was performed using alternately 5.25% NaOCl and 17% EDTA, followed by rinsing with saline. The roots were split longitudinally into halves and the canals examined at ×200 and ×400 in a scanning electron microscope. The presence of debris and smear layer was recorded at distances of 1, 5 and 10 mm from the working length using a three-step scoring scale and a 300 ,m square grid. Mean scores for debris and smear layer were calculated and statistically analysed for significance (P < 0.05) between and within groups, using the Kruskal,Wallis nonparametric anova and Dunn's tests. Results, At 1, 5 and 10-mm levels the root canals prepared with AET had significantly less surface debris and smear layer on the canal walls compared with canals prepared with ProFile or manual instrumentation. For all three groups significantly lower mean smear layer scores (P < 0.05) were recorded at 5 and 10-mm levels compared with the 1 mm level. Significantly lower mean debris scores (P < 0.05) were also recorded at 5 and 10-mm levels for the AET group whereas no significant differences were found between the three levels for the ProFile and manual instrumentation groups. Conclusions, Although better instrumentation scores were obtained in canals prepared with AET, complete cleanliness was not achieved by any of the techniques and instruments investigated. [source] The critical-size supraalveolar peri-implant defect model: characteristics and useJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 11 2006Ulf 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] The effect of a fibrin glue on the integration of Bio-Oss® with bone tissueJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 5 2002An experimental study in labrador dogs Abstract Background: Bio-Oss® is a deproteinized bovine mineral used in bone augmentation procedures. The particles are often mixed with a protein product (Tisseel®) to form a mouldable graft material. Aim: The aim of the present experiment was to study the healing of self-contained bone defects after the placement of Bio-Oss® particles alone or mixed with Tisseel® in cylindrical defects in the edentulous mandibular ridge of dogs. Material and methods: In 4 labrador dogs, the 2nd, 3rd and 4th mandibular premolars were extracted bilaterally. 3 months later, 3 cylindrical bone defects, 4 mm in diameter and 8 mm in depth, were produced in the right side of the mandible. Following a crestal incision, full thickness flaps were raised and the bone defects were prepared with a trephine drill. The defects were filled with Bio-Oss® (Geistlich Biomaterials, Wolhuser, Switzerland) particles alone or mixed with Tisseel® (Immuno AG, Vienna, Austria), or left "untreated". A collagen membrane (Bio-Gide®, Geistlich Biomaterials, Wolhuser, Switzerland) was placed to cover all defects and the flaps were sutured. 2 months later, the defect preparation and grafting procedures were repeated in the left side of the mandible. After another month, the animals were sacrificed and biopsies obtained from the defect sites. Results: Bio-Oss® -treated defects revealed a higher percentage of contact between graft particles and bone tissue than defects treated with Bio-Oss®+ Tisseel® (15% and 30% at 1 and 3 months versus 0.4% and 8%, respectively). Further, the volume of connective tissue in the Bio-Oss® treated defects decreased from the 1 to the 3 month interval (from 44% to 30%). This soft tissue was replaced with newly formed bone. In the Bio-Oss®+ Tisseel® treated defects, however, the proportion of connective tissue remained unchanged between 1 and 3 months. Conclusion: The adjunct of Tisseel® may jeopardize the integration of Bio-Oss® particles with bone tissue. Zusammenfassung Hintergrund: Bio-Oss® ist ein entproteiniertes Mineral vom Schwein, was bei knöchernen Augmentationen verwendet wird. Die Partikel werden oft mit einem Proteinprodukt gemischt, um ein formbares Implantationsmaterial zu erhalten. Ziel: Das Ziel des vorliegenden Experimentes war das Studium der Heilung von selbst-erhaltenden Knochendefekten nach der Anwendung von Bio-Oss® Partikeln allein oder vermischt mit Tisseel® in zylindrischen Defekten im zahnlosen unteren Kieferkamm von Hunden. Materal und Methoden: Bei 4 Labradorhunden wurden die 2., 3. und 4. unteren Prämolaren beidseitig extrahiert. 3 Monate später wurden 3 zylindrische Knochendefekte, 4 mm im Durchmesser und 8 mm tief, auf der rechten Seite des Unterkiefers hergestellt. Nach einer krestalen Incision wurde ein voller Mukoperiostlappen mobilisiert und die knöchernen Defekte mit einem Trepanfräser präpariert. Die Defekte wurden mit Bio-Oss® Partikeln (Geistlich Biomaterial, Wolhuser, Schweiz) allen oder gemischt mit Tisseel® (Immuno AG, Wien, Österreich) gefüllt oder blieben "unbehandelt". Eine Kollagenmembran (Bio-Gide®, Geistlich Biomaterial, Wolhuser, Schweiz) wurde zur Abdeckung über alle Defekte gelegt und die Lappen reponiert und vernäht. 2 Monate später wurden die Defektpräparationen und die Implantationsmaßnahmen auf der linken Seite des Unterkiefers widerholt. Nach einem weiteren Monat wurden die Tiere getötet und Biopsien von den Defektseiten gewonnen. Ergebnisse: Mit Bio-Oss® behandelte Defekte zeigten einen höheren Prozentsatz von Kontakt zwischen Implantationsmaterial und Knochengewebe als die Defekte, die mit Bio-Oss® und Tisseel® behandelt worden waren (15% und 30% zum 1. Monat und 3. Monat versus 0.4% und 8%). Weiterhin verringerte sich das Volumen des Bindegewebes in den mit Bio-Oss® behandelten Defekten vom 1. zum 3. Monat (von 44% zu 30%). Dieses Weichgewebe wurde mit neu gebildetem Knochen ersetzt. In dem mit Bio-Oss® und Tisseel® behandelten Defekten blieb die Verteilung des Bindegewebes zwischen dem 1. und 3. Monat unverändert. Zusammenfassung: Die Zugabe von Tisseel® kann die Integration von Bio-Oss® Partikeln mit Knochengewebe behindern. Résumé Origine: Le Bio-Oss® est un minéral bovin déprotéine utilisé pour les épaississements osseux. Les particules sont souvent mélangées avec un produit protéiné (Tisseel®) pour former un matérial de greffe malléable. But. Le but de l'étude présente a été d'étudier la guérison des lésions osseuses après le placement de particules de Bio-Oss® seules ou mélangées au Tisseel® dans des lésions cylindriques au niveau de la mandibule édentée de labradors. Matériaux et méthodes: Chez 4 labradors les 2ièmes, 3ièmes et 4ièmes prémolaires inférieures ont été avulsées bilatéralement. 3 mois après, 3 lésions osseuses et cylindriques de 4 mm de diamètre et de 8 mm de profondeur ont été produites du côté droit de la mandibule. A la suite d'une incision crestale, des lambeaux d'épaisseur complète ont été relevés et les lésions osseuses préparées avec un trépan. Les lésions ont été comblées par des particules de Bio-Oss® seul (Geistlich Biomaterials, Wolhuser, Suisse) ou mélangées au Tisseel® (Immuno AG, Vienne) ou laissées non-traitées. Une membrane collagène (Bio-Gide®, Geistlich Biomaterials, Wolhuser, Suisse) a été placée pour recouvrir toutes les lésions et les lambeaux ont ensuite été suturés. 2 mois après, les processus précités ont été répétés au niveau gauche de la mandibule. 1 mois plus tard, les animaux ont été tués et les biopsies prélevées. Résultats: Les lésions traitées par le Bio-Oss® ont révélé un % plus important de contact entre les particules du greffon et le tissu osseux que les lésions traitées avec le Bio-Oss®+Tisseel® (respectivement 15% à 30% à 1 et 3 mois versus 0.4% et 8%). De plus le volume de tissu conjonctif dans les lésions traitées par Bio-Oss® diminuait du mois 1 au mois 3, de 44 à 30%. Ce tissu mou a été remplacé par un os néoformé. Dans les lésions traitées par Bio-Oss®+Tisseel®, la proportion de tissu conjonctif demeurait inchangée entre les mois 1 et 3. Conclusions: L'addition de Tisseel® peut mettre en péril l'intégration des particules de Bio-Oss® au tissu osseux. [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] Fracture Resistance of Endodontically Treated Teeth: Three Walls versus Four Walls of Remaining Coronal Tooth StructureJOURNAL OF PROSTHODONTICS, Issue 1 2009Siriporn Arunpraditkul DDS Abstract Purpose: The purpose of this study was to evaluate the fracture resistance of endodontically treated teeth between those with four walls and those with three walls of remaining coronal tooth structure and the effect of the site of the missing coronal wall. Materials and Methods: Thirty-two endodontically treated second mandibular premolars were decoronated, leaving 3 mm above the cementoenamel junction (CEJ). A 0.5-mm-wide chamfer was prepared 1 mm above the CEJ. The teeth were randomly divided into four groups. Group 1 had four walls of coronal tooth structure, whereas groups 2, 3, and 4 had only three walls, missing the buccal, lingual, and mesial wall, respectively. The cast dowel and cores and crowns (Ni,Cr alloy) were cemented with zinc phosphate cement. A compressive load was applied 45° to the long axis, 2 mm below the buccal cusp, with an Instron machine until failure at a crosshead speed of 5 mm/min. Failure load (kg) and mode of failure were recorded. Data were analyzed with one-way ANOVA and Scheffé tests (p < 0.05). Results: Group 1 had the highest fracture resistance (1190.3 ± 110.5 kg), significantly different from the other groups (p < 0.05) (group 2: 578.5 ± 197.4 kg; group 3: 786.6 ± 132.8 kg; group 4: 785.4 ± 289.9 kg). There were no significant differences among the test groups. The mode of failure in group 1 was a horizontal root fracture, whereas that of the other groups was either vertical or oblique fracture. Conclusions: Teeth with four walls of remaining coronal dentine had significantly higher fracture resistance than teeth with only three walls. The site of the missing coronal wall did not affect the fracture resistance of endodontically treated teeth. [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] Immediate Functional Loading of Single-Tooth TIO2 Grit-Blasted Implant Restorations: A Controlled Prospective Study in a Porcine Model.CLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 4 2007Part I: Clinical Outcome ABSTRACT Background:, Although favorable integration occurs with immediately loaded implants, the relationship between implant outcome, levels of occlusion, and diet requires optimization. Purpose:, Pertubating load on single implant restorations immediately after placement by a hard food diet will increase the strains at the bone-implant interface, increasing the risk for failure. Materials and Methods:, Forty-eight implants replaced the first and third mandibular premolars in 12 pigs, allocated into two groups based on soft- and hard-diet feeding. Cylindrical and tapered implants replaced the first and third premolars, respectively. Each animal received at random four different masticatory loading conditions (group 1 control]: implant with either a cover screw or a healing abutment, and group 2 test]: implant with a crown either with or without occlusal contacts). Results:, Thirteen implants out of 44 failed in 11 animals (one with a cover screw, one with a healing abutment, three with nonocclusal, and eight with occlusal restorations). The failure rate of restored implants (either in occlusion or not) was significantly higher in the third premolar sites (p=.007), although diet had no significant effect (p=.421). Conclusions:, While diet had no effect on the failure pattern of immediately loaded single implants, the position and type of load under the masticatory mode were significant. Immediately loaded implants both in and out of occlusion were less successful than the controls, and this is probably attributed to detrimental strain induced on the bone-implant interface. [source] Effects of Implant Design and Surface on Bone Regeneration and Implant Stability: An Experimental Study in the Dog MandibleCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 1 2001Lars Rasmusson DMD ABSTRACT Background: Previous experimental studies have shown a higher degree of bone-implant contact for surface-enlarged implants compared with machined implants. Yet, there is insufficient evidence that such implants show higher stability and an increased survival rate. Purpose: The purpose of this investigation was to study the integration and stability of grit-blasted implants with retention elements on the implant neck, with and without marginal bone defects, compared with machined implants without retention elements. Materials and Methods: After tooth extraction of the mandibular premolars in six dogs, two grit-blasted, partly microthreaded Astra Tech implants and one standard Branemark implant were bilaterally placed in each dog. On one side, 3 ± 3 mm large buccal defects were created, to expose three to four implant threads. The contralateral side served as control, and no defects were made. The animals were sacrificed after 4 months of healing. Implant stability was measured using resonance frequency analysis at implant installation and after 4 months of healing. Histologic and histomorpho-metric evaluation was made after 4 months of healing. Results: Resonance frequency analysis indicated that all implants in the test and control groups were osseointegrated after 4 months, with a tendency toward higher implant stability for the Astra Tech implants. There was a statistically significant higher increase in resonance frequency for the Astra test implants compared with their corresponding controls. Histology and histomorphometry showed well-integrated implants with varying degrees of bone repair at the defect sites. The greater bone-implant contact for the Astra implants was statistically significant. No significant difference between the implants in amount of bone filling the threads was recorded. Conclusions: The Astra Tech implants tested showed a higher degree of bone,implant contact and higher level of bone regenerated at defect sites compared with the Brånemark implants. Resonance frequency analysis demonstrated a significantly higher increase in the Astra test implants compared with their control groups than did the Brånemark test implants versus their controls. [source] Influence of interimplant distances and placement depth on peri-implant bone remodeling of adjacent and immediately loaded Morse cone connection implants: a histomorphometric study in dogsCLINICAL ORAL IMPLANTS RESEARCH, Issue 4 2010Raquel R. M. Barros Abstract Objectives: The aim of this study was to histomorphometrically evaluate the influence of interimplant distances (ID) and implant placement depth on bone remodeling around contiguous Morse cone connection implants with ,platform-shifting' in a dog model. Material and methods: Bilateral mandibular premolars of six dogs were extracted, and after 12 weeks, each dog received 8 implants, four placed 1.5 mm subcrestally (SCL) on one side of the mandible and four placed equicrestally (ECL) on the other side, alternating the ID of 2 and 3 mm. The experimental groups were SCL with IDs of 2 mm (2 SCL) and 3 mm (3 SCL) and ECL with IDs of 2 mm (2 ECL) and 3 mm (3 ECL). Metallic crowns were immediately installed. After 8 weeks, the animals were euthanized and histomorphometric analyses were performed to compare bone remodeling in the groups. Results: The SCL groups' indices of crestal bone resorption were significantly lower than those of ECL groups. In addition, the vertical bone resorption around the implants was also numerically inferior in the SCL groups, but without statistical significance. No differences were obtained between the different IDs. All the groups presented similar good levels of bone-to-implant contact and histological bone density. Conclusion: The subcrestal placement of contiguous Morse cone connection implants with ,platform shifting' was more efficient in preserving the interimplant crestal bone. The IDs of 2 and 3 mm did not affect the bone remodeling significantly under the present conditions. To cite this article: Barros RRM, Novaes AB Jr., Muglia VA, Iezzi G, Piattelli A. Influence of interimplant distances and placement depth on peri-implant bone remodeling of adjacent and immediately loaded Morse cone connection implants: a histomorphometric study in dogs. Clin. Oral Impl. Res. 21, 2010; 371,378. doi: 10.1111/j.1600-0501.2009.01860.x [source] Ridge alterations following tooth extraction with and without flap elevation: an experimental study in the dogCLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2009Mauricio G. Araújo Abstract Background: Different approaches were advocated to preserve or improve the dimension and contour of the ridge following tooth extraction. In some of studies, socket ,flapless extraction' apparently had a successful outcome. Aim: The objective of the present experiment was to compare hard tissue healing following tooth extraction with or without the prior elevation of mucosal full-thickness flaps. Material and methods: Five mongrel dogs were used. The two second mandibular premolars (2P2) were hemi-sected. The mesial roots were retained. By random selection the distal root in one side was removed after the elevation of full-thickness flaps while on the contralateral side, root extraction was performed in a flapless procedure. The soft tissue wound was closed with interrupted sutures. After 6 months of healing, the dogs were euthanized and biopsies were sampled. From each experimental site, four ground sections , two from the mesial root and two from the healed socket , were prepared, stained and examined in the microscope. Results: The data showed that the removal of a single tooth (root) during healing caused a marked change in the edentulous ridge. In the apical and middle portions of the socket site minor dimensional alterations occurred while in the coronal portion of the ridge the reduction of the hard tissue volume was substantial. Similar amounts of hard tissue loss occurred during healing irrespective of the procedure used to remove the tooth was, i.e. flapless or following flap elevation. Conclusion: Tooth loss (extraction) resulted in marked alterations of the ridge. The size of the alveolar process was reduced. The procedure used for tooth extraction , flapless or following flap elevation , apparently did not influence the more long-term outcome of healing. [source] Evaluation of a new biodegradable membrane to prevent gingival ingrowth into mandibular bone defects in minipigsCLINICAL ORAL IMPLANTS RESEARCH, Issue 1 2009Daniel S. Thoma Abstract Objective: The aim of this study was to test whether a synthetic, biodegradable membrane made of polyethylene glycol (PEG) can prevent soft-tissue ingrowth into alveolar defects. Material and methods: In each of 16 minipigs, three mandibular premolars were bilaterally extracted. Three months later, acute standardized defects (diameter 8 mm, depth 8 mm) were prepared. Four treatment modalities were randomly allocated to the defects: (1) PEG membrane plus collagen sponge, (2) polylactide (PLA) membrane plus collagen sponge, (3) collagen sponge alone, and (4) empty defect. Animals were sacrificed at 10 days (n=5), 21 days (n=5), or 2 months (n=6) after treatment. Qualitative and quantitative histological evaluations of soft-tissue ingrowth and bone regeneration were performed on nondecalcified ground sections. For statistical analysis, the Mann,Whitney,Wilcoxon test, the Kruskal,Wallis, and the paired t -test were applied. P -values were adjusted using the Dunnett,Hsu adjustment. Results: At 10 days, the PEG membrane group showed the least soft-tissue ingrowth (mean value ,0.75 mm; range ,1.35 to ,0.10), followed by the PLA membrane group ,0.18 mm (,0.80 to 0.44), the collagen group 0.04 mm (,0.65 to 0.73), and the empty defects 0.60 mm (,0.08 to 1.29). Statistically significant differences were observed between the PEG membrane group and the empty defects (P<0.05). At 21 days, the highest percentage of newly formed bone was found in the PEG membrane group (mean 28.4%; range 21.6,35.2) compared with 23.7% (16.9,30.5; PLA membrane), 15.2% (8.2,22.2; collagen group), and 21.6% (14.5,28.8; empty defects). Statistically significant differences were only found between the PEG membrane group and the collagen group (P<0.05). At 2 months, the tested parameters revealed no statistically significant differences between the groups. Conclusion: The experimental PEG membrane applied in the present study successfully prevented collapse of the covering soft tissues to a degree similar to the PLA membrane. The combination of a collagen sponge and the PEG membrane showed the least soft-tissue ingrowth at 10 days and promoted more bone formation at 21 days. [source] Bone apposition around two different sandblasted and acid-etched titanium implant surfaces: a histomorphometric study in canine mandiblesCLINICAL ORAL IMPLANTS RESEARCH, Issue 3 2008Michael M. Bornstein Abstract Purpose: The aim of this study was to evaluate bone apposition to a modified sandblasted and acid-etched (SLA) implant surface (modSLA) in the canine mandible as compared with the standard SLA surface. Material and methods: In this experimental study, all mandibular premolars and first molars were extracted bilaterally in five foxhounds. After a healing period of 6 months, each side of the mandible received six randomly assigned dental implants alternating between the standard SLA and modSLA surface. The dogs were sacrificed at 2 weeks (n=2) or 4 weeks (n=3) after implant placement. Histologic and histomorphometric analyses were then performed for each implant. Results: The microscopic healing patterns at weeks 2 and 4 for the two implant types with the standard SLA and modSLA surfaces showed similar qualitative findings. New bone tissue had already established direct contact with implant surfaces after 2 weeks of healing. The mean percentage of newly formed bone in contact with the implant (BIC) was significantly greater for modSLA (28.2±7.9%) than for SLA (22.2±7.3%) (P<0.05). This difference was no longer evident after 4 weeks. An increase in BIC for both implant surface types occurred from weeks 2 to 4. This increase was statistically significant when compared with SLA at 2 weeks (P<0.05), but not when compared with modSLA at 2 weeks. Conclusion: The data from the present study demonstrate significantly more bone apposition for the modSLA surface than the standard SLA surface after 2 weeks of healing. This increased bone apposition may allow a further reduction of the healing period following implant placement for patients undergoing early loading procedures. [source] Implant stability during osseointegration in irradiated and non-irradiated minipig alveolar bone: an experimental studyCLINICAL ORAL IMPLANTS RESEARCH, Issue 2 2008Henk W. D. Verdonck Abstract: Objectives: Primary implant stability is related to local bone density. After insertion of an implant, implant stability is subject to changes due to bone remodeling. In patients who have undergone radiotherapy in the head and neck region, implant stability is impaired because irradiation reduces bone vitality. The current study was designed to monitor and test implant stability immediately after implant placement and during osseointegration in irradiated and non-irradiated minipig alveolar bone. Materials and methods: All maxillary and mandibular premolars and molars of six adult Göttingen minipigs were extracted. The maxilla and mandible of three minipigs received three irradiation exposures at a total dose of 24 Gy. After irradiation, five initial implant holes were drilled in the residual alveolar ridge of each edentulous site. In order to assess bone vascularity, laser Doppler flowmetry recordings were carried out in the initial holes. A total of 120 implants were placed in the six minipigs. Subsequently, and at 8, 16, and 24 weeks after implant placement, implant stability was recorded by resonance frequency analysis (RFA). RFA values were expressed as an implant stability quotient (ISQ). Results: ISQ values recorded immediately after implant placement showed no differences between irradiated and non-irradiated minipigs. Repeated measurements at the four recording moments showed a decrease of ISQ values in all minipigs, being more pronounced in irradiated bone, when compared with non-irradiated bone. The results at the third and fourth recording moments showed a stabilization or even a slight increase of ISQ values. Conclusions: The results document the negative effect of irradiation on bone vascularity and hence on implant stability. [source] | ||||||||||||||||||||||