Showing papers in "Clinical Oral Implants Research in 2000"

Anatomical aspects of sinus floor elevations

Abstract: Inadequate bone height in the lateral part of the maxilla forms a contra-indication for implant surgery. This condition can be treated with an internal augmentation of the maxillary sinus floor. This sinus floor elevation, formerly called sinus lifting, consists of a surgical procedure in which a top hinge door in the lateral maxillary sinus wall is prepared and internally rotated to a horizontal position. The new elevated sinus floor, together with the inner maxillary mucosa, will create a space that can be filled with graft material. Sinus lift procedures depend greatly on fragile structures and anatomical variations. The variety of anatomical modalities in shape of the inner aspect of the maxillary sinus defines the surgical approach. Conditions such as sinus floor convolutions, sinus septum, transient mucosa swelling and narrow sinus may form a (usually relative) contra-indication for sinus floor elevation. Absolute contra-indications are maxillary sinus diseases (tumors) and destructive former sinus surgery (like the Caldwell-Luc operation). The lateral sinus wall is usually a thin bone plate, which is easily penetrated with rotating or sharp instruments. The fragile Schneiderian membrane plays an important role for the containment of the bonegraft. The surgical procedure of preparing the trap door and luxating it, together with the preparation of the sinus mucosa, may cause a mucosa tear. Usually, when these perforations are not too large, they will fold together when turning the trap door inward and upward, or they can be glued with a fibrin sealant, or they can be covered with a resorbable membrane. If the perforation is too large, a cortico-spongious block graft can be considered. However, in most cases the sinus floor elevation will be deleted. Perforations may also occur due to irregularities in the sinus floor or even due to immediate contact of sinus mucosa with oral mucosa. Obstruction of the antro-nasal foramen is, due to its high location, not a likely complication, nor is the occurrence of severe haemorrhages since the trap door is in the periphery of the supplying vessels. Apart from these two aspects, a number of anatomical considerations are described in connection with sinus floor elevation.

Biological complications with dental implants: their prevention, diagnosis and treatment.

Abstract: Biofilms form on all hard non-shedding surfaces in a fluid system, i.e. both on teeth and oral implants. As a result of the bacterial challenge, the host responds by mounting a defence mechanism leading to inflammation of the soft tissues. In the dento-gingival unit, this results in the well-described lesion of gingivitis. In the implanto-mucosal unit, this inflammation is termed “mucositis”. If plaque is allowed to accumulate for prolonged periods of time, experimental research has demonstrated that “mucositis” may develop into “periimplantitis” affecting the periimplant supporting bone circumferentially. Although the bony support may be lost coronally, the implant still remains osseointegrated and hence, clinically stable. This is the reason why mobility represents an insensitive, but specific diagnostic feature of “periimplantitis”. More sensitive and more reliable parameters of developing and existing periimplant infections are “bleeding on probing”, “probing depths” and radiographic interpretation of conventional or subtraction radiographs. Depending on the diagnosis made continuously during recall visits, a maintenance system termed Cummulative Interceptive Supportive Therapy (CIST) has been proposed.

Considerations preliminary to the application of early and immediate loading protocols in dental implantology.

Abstract: In oral implantology, a 3-6 month stress-free healing period is presently accepted as a prerequisite to achieve bone apposition without interposition of a fibrous scar tissue. This protocol was introduced by Branemark and co-workers in 1977. The aim of the present paper is to review the reasons that led Branemark and collaborators to require long delayed loading periods. It is shown that the requirement for long delayed loading periods was drawn from the initiation and development periods of their original clinical trial. Demanding conditions were met involving simultaneously: 1) patients with poor bone quality and quantity, 2) non-optimized implant design, 3) short implants, 4) non-optimized surgical placement, 5) non-optimized surgical protocol and 6) biomechanically non-optimized prosthesis. Extrapolation of the requirement for long healing periods from these particular conditions to more standard situations involving refined surgical protocols and careful patient selection might be questioned. Albeit premature loading has been interpreted as inducing fibrous tissue interposition, immediate loading per se is not responsible for fibrous encapsulation. It is the excess of micromotion during the healing phase that interferes with bone repair. A threshold of tolerated micromotion exists, that is somewhere between 50 microns and 150 microns. It is suggested that loading protocols might be shortened through 2 different approaches. The first way would be to decrease stepwise the delayed loading period for free-standing implants below the presently accepted 3-6 months of healing. The second way would be to identify immediate loading protocols that are capable of keeping the amount of micromotion beneath the threshold of deleterious micromotion. Immediate loading protocols for implants-retained overdentures and fixed bridges are reviewed. It is shown that successful premature loading protocols require a careful and strict patient selection aimed to achieve the best primary stability. These various protocols need to be further documented in order to assess their predictability.

Mechanical complications of dental implants.

Abstract: Adverse occlusal forces can result in mechanical complications of implant components. While unacceptably high incidences of mechanical failures have been reported for the two-stage external hex screw-type implant systems, the standard-diameter ITI solid-screw implant does not seem to be vulnerable to these problems. The 8 degrees Morse taper has eliminated abutment screw loosening and fracture. The incidence of prosthetic screw loosening has been minimized by the 45 degrees bevel on the implant shoulder and by the 1.5 mm vertical abutment walls. The design of the standard-diameter solid-screw ITI implant and the material used in its fabrication (cold worked type IV cp titanium) have eliminated fixture fracture. However, because there have been some reported instances of fractures involving reduced-diameter and hollow implants, these designs should be used with caution.

Maxillary sinus augmentation using xenogenic bone substitute material Bio-Oss® in combination with venous blood

Abstract: The aim of the present study was to evaluate bone formation following maxillary sinus augmentation using bovine bone substitute material Bio-Oss in combination with venous blood by means of histologic and histomorphometric examination of human biopsies. This involved a total of 15 sinus floor elevation procedures being carried out on 11 patients (average age of 49.6 years) according to the technique described by Tatum (1986). The subantral sinus cavity was augmented using bovine apatite combined with venous blood. After an average healing phase of 6.8 months, trephine burrs were used to take 22 bone biopsies from the augmented sinus region. Then 38 Branemark implants were inserted in both the osteotomies resulting from bone sampling and in regular sites in the augmented posterior maxilla. Histomorphometric analysis of ground sections from the bone biopsies prepared according to the standard method of Donath & Breuner (1982) produced an average percentage of newly-formed bone of 14.7% (+/- 5.0%) and a proportion of residual xenogenic bone substitute material of 29.7% (+/- 7.8%). Some 29.1% (+/- 8.1%) of the surface of the Bio-Oss granulate was in direct contact with newly-formed bone. Histologically, newly-developed bone became evident, partly invaginating the particles of apatite and forming bridges in the form of trabeculae between the individual Bio-Oss particles. Despite the absence of osteoclastic activity, the inward growth of bone indicates slow resorption of the xenogenic bone graft material. When the implants were uncovered, after an average healing phase of 6 months, 4 of the 38 implants had become loose. Of these 4 implants, 1 had to be subsequently explanted, while the others remained as "sleeping implants" and were not included in the implants superstructure. Thus, the resulting clinical survival rate, prior to prosthetic loading, was 89.5%.

Biologic width around titanium implants. A physiologically formed and stable dimension over time

Abstract: Research in implant dentistry has mainly focused on hard tissue integration with much less data available with regards to soft tissue integration involving epithelium and connective tissue. In the present study, the implantogingival junction of unloaded and loaded non-submerged titanium implants has been analyzed histometrically in the canine mandible. In 6 foxhounds, 69 implants were placed. Dogs in the unloaded group were sacrificed 3 months after implant placement. Loaded implants were restored with gold crowns and those dogs were sacrificed after 3 months and 12 months of loading. Non-decalcified histologic sections were analyzed histometrically measuring the dimensions of the Sulcus Depth (SD), the Junctional Epithelium (JE), and the Connective Tissue Contact (CTC). Histometric evaluation revealed that significant changes within tissue compartments (SD, JE, CTC) occurred over time (P 0.05). These data indicate that the Biologic Width is a physiologically formed and stable structure over time in the case of non-submerged, one-piece titanium implants as evaluated histometrically under unloaded and loaded conditions. Dynamic changes did occur, however, within the overall Biologic Width dimension. Thus, the use of non-submerged, one-piece implants allow for stable overall peri-implant soft tissues as evaluated under loaded conditions for up to 12 months.

Management of the edentulous patient.

Abstract: Being edentulous is a handicap, and the main objective of implant placement is to provide support of fixed prostheses or to stabilize complete dentures in the edentulous jaw. Clinical experience and clinical studies have demonstrated the broad application of non-submerged ITI implants in prosthetic therapy in standard sites and in situations of advanced atrophy or substantial loss of tissue. The ITI implant was developed for universal use in partially and completely edentulous patients and for replacement of single missing teeth. The abutment system offers the choice of both removable and fixed prostheses with identical secondary parts. The present article describes the use of ITI implants for prosthodontic rehabilitation in the completely edentulous jaw. Indications and various types of fixed or removable prostheses, alternatives and variations of design are discussed. Prosthetic design is dependent on the number and location of implants, and conversely, the number of implants that can be placed will determine the choice of prosthesis. Treatment planning in general and with respect to individual anatomic-morphologic conditions is described for the upper and lower jaw. Details of clinical procedures with ITI implants related to the specific design of prostheses are presented. Biomechanical aspects of fixation and stabilization of prostheses and aspects of occlusion to be built up complete the overview.

Immediate functional loading of Brånemark single tooth implants

Abstract: A clinical and radiographical study was performed to evaluate the treatment outcome of single tooth replacements with artificial crowns retained to implants installed according to a 1-stage surgical procedure and immediate loading (Experimental Group = EG) in comparison to the original 2-stage concept (Control Group = CG). The EG comprised 14 patients (= 14 implants) and the CG comprised 8 patients (= 8 implants), all with single tooth losses anterior to the molars. Beyond the non-smoking criterion the following criteria were adopted: i) the amount of bone had to allow for installation of a fixture with a minimum length of 13 mm and O = 3.75 mm, ii) the jaw relationship had to allow for bilateral occlusal stability, iii) the patients should be judged to be non-bruxers, and iv) the patients had to be available for the follow-up and maintenance programme. In the EG a temporary crown was connected to the implant within 24 h following fixture installation. Six months later this crown was replaced with a permanent one. In the CG the surgical and prosthetic treatment followed the standard protocol. Out of the 14 fixtures in the EG 2 were lost up to 5 months in function and were subsequently removed. All remaining 12 implants were stable at every subsequent follow-up examination. No fixture losses were recorded in the CG and all implants in this group were stable at the follow-ups. At the 6-month observation interval all the participating 20 patients were radiographically examined, an examination that was repeated at the 18-month follow-up. The analysis of the radiographs from the EG as well as from the CG disclosed that during the 12-month observation period the mean change of bone support was about 0.1 mm. Further studies, designed as controlled multicenter ones, have to be performed before the results of this pilot study can be recommended for more general use.

Red blood cell and platelet interactions with titanium implant surfaces.

Abstract: The influence of the micro-roughened surface, produced by dual acid-etching (DAE) of machined commercially pure titanium, on initial blood cell/implant interactions was investigated by observing the blood components remaining at the implant surface following freeze-fracture of clotted, and fixed, human blood. Glass surfaces were also used for immunolabelling studies to identify fibrin and platelets. The interface comprised predominantly fibrin and red blood cells (RBCs). The difference in distribution of RBCs was statistically significant (P < 0.05) at 10 min of blood/implant contact, but diminished thereafter. Micro-roughened DAE implant surfaces showed, qualitative, more platelets than machined surfaces, while the textured glass surfaces demonstrated increased platelet aggregation. We believe that these early blood cell/implant interactions may play a key role in the osteoconduction stage of peri-implant bone healing response to micro-roughened implants.

A 5-year prospective clinical and radiographic study of non-submerged dental implants.

Abstract: Osseointegrated implants as anchors for various prosthetic reconstructions have become a predictable treatment alternative It was expected that implants required submucosal placement during the healing period for successful tissue integration However, it has been demonstrated that healing and long-term health of implants could be achieved with equal predictability in a 1-stage, non-submerged approach This prospective 5-year study not only calculates implant success by life table analysis, but also evaluates the correlation between observed bone level changes with clinical parameters as measured by suppuration, plaque indices, bleeding indices, probing depth, attachment level and mobility A total of 112 ITI dental implants were inserted in different areas of the jaws Clinical and radiographic parameters were evaluated annually for 5 years, whereas a portion of the study group for which 6-year evaluations were available were included in the life-table analysis The overall success rate after 5 years in service was 991%, while after 6 years it was reduced to 955% due to the fracture of 3 implants in 1 patient The mean crestal bone loss experienced during the first year was 06 mm followed by an annual yearly loss of approximately 005 mm No significant differences could be found between the amount of bone loss measured at each of the yearly follow-up visits This suggests that statistically the followed implants did not show any radiographically measurable bone loss following the initial period of bone loss associated with implant placement and osseointegration Low levels of correlation between the individual and cumulative clinical parameters with radiographically measured bone loss suggests that these parameters are of limited clinical value in assessing and predicting future peri-implant bone loss

Magnitude and distribution of occlusal forces on oral implants supporting fixed prostheses: an in vivo study

Abstract: Since loading is increasingly believed to be a determining factor in the treatment outcome with oral implants, there is a need to expand the knowledge related to the biomechanics of oral implants. The aim of this study is to gain insight in the distribution and magnitude of occlusal forces on oral implants carrying fixed prostheses. This is done by in vivo quantification and qualification of these forces, which implies that not only the magnitude of the load but also its type (axial force or bending moment) will be registered. A total of 13 patients with an implant supported fixed full prosthesis were selected. Occlusal forces on the supporting implants were quantified and qualified during controlled load application of 50 N on several positions along the occlusal surface of the prostheses and during maximal biting in maximal occlusion by use of strain gauged abutments. The test was conducted when the prostheses were supported by all (5 or 6) implants and was repeated when the prostheses were supported by 4 and by 3 implants only. Despite considerable inter-individual variation, clear differences in implant loading between these test conditions were seen. Loading of the extension parts of the prostheses caused a hinging effect which induced considerable compressive forces on the implants closest to the place of load application and lower compressive or tensile forces on other implants. On average, higher forces were observed with a decreasing number of supporting implants. Bending moments were highest when 3 implants only were used.

Early colonization of dental implants by putative periodontal pathogens in partially edentulous patients

Abstract: There is limited scientific information available on the early colonization of the peri-implant pockets in partially edentulous individuals. Knowledge about this process is one step in better understanding the etiology and pathogenesis of peri-implantitis. In this study, the early colonization of the peri-implant pockets by putative periodontal pathogens was studied in 20 partially edentulous individuals using anaerobic culture techniques. At baseline, the presence and levels of putative periodontal pathogens in the microflora of periodontal pockets and saliva were established. Immediately after loading of the titanium implants and after 6 and 12 months the presence and levels of selected putative periodontal pathogens were determined in periodontal and peri-implant pockets. A second aim was to detect bacterial contamination of the implant site and the inside of the implant. At baseline, the most frequently isolated species from the periodontal pockets were Fusobacterium nucleatum, Prevotella intermedia and Peptostreptococcus micros. Bacteroides forsythus, Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis were isolated from 9, 2 and 3 patients respectively. Six months after placing of the bridges, the majority of the implant sites had detectable levels of most periodontal bacterial species with the exception of A. actinomycetemcomitans which could not be isolated from any of the peri-implant samples during the experimental period, although 2 patients had this organism at baseline. In 2 patients with detectable subgingival P. gingivalis at baseline this species was found after 12 months in the peri-implant sites. One of these patients lost 2 implants which was associated with a high proportion of P. gingivalis in the peri-implant pockets. A second patient developed 2 fistulas around 2 implants at 8 months and this event was also associated with the presence of P. gingivalis. It is concluded that proper periodontal infection control before instalment of dental implants in partially edentulous patients may prevent early bacterial complications.

Biostimulation of bone marrow cells with a diode soft laser.

Abstract: In recent years, the use of low-intensity red light in regeneration of soft tissue has been increasingly pursued. As far as hard tissue is concerned, the biostimulating effect of laser has already been demonstrated successfully in more rapid healing of tibial bone fractures in mice at a dosage of 2.4 J. However, the effect of light of a low dose laser directly on osteoblasts has not been investigated yet. The aim of this study was to determine the effect of continuous wave diode laser irradiation on osteoblasts derived mesenchymal cells. Three groups of 10 cultures each were irradiated 3 times (days 3, 5, 7) with a pulsed diode soft laser with a wavelength of 690 nm for 60 s. Another 3 groups of 10 cultures each were used as control groups. A newly developed method employing the fluorescent antibiotic tetracycline was used to compare bone growth on these culture substrates after a period of 8, 12 and 16 days, respectively. It was found that all lased cultures demonstrated significantly more fluorescent bone deposits than the non-lased cultures. The difference was significant, as tested by the Tukey Test (P < 0.0001) in the cultures examined after 16 days. Hence it is concluded that irradiation with a pulsed diode soft laser has a biostimulating effect on osteoblasts in vitro, which might be used in osseointegration of dental implants.

Basic surgical principles with ITI implants.

Abstract: The basic surgical principles governing the placement of ITI implants are based on research-oriented developments in harmony with evidence-based and outcome-oriented clinical procedures. In the past 15 years, the range of implant indications has been significantly widened, and partially edentulous patients clearly represent the majority of patients seeking treatment with dental implants today. An important aspect of the successful rehabilitation of patients with ITI implants is the careful selection of implant candidates with respect to systemic and local risk factors. These factors are presented based on current knowledge. Today, solid-screw implants in various screw dimensions and neck configurations comprise the ITI Dental Implant System. These different implant types are necessary to handle the full range of implant indications, in particular in partially edentulous patients. The main clinical factors are presented for the selection of the appropriate implant type, length and diameter. These implants are utilized both in a non-submerged and in a submerged approach. The main goal of surgical therapy is low trauma and the least demanding surgical procedure for patient and clinician to optimize the cost-effectiveness of implant therapy. Hence, a non-submerged approach is preferred in all sites without esthetic priority, such as in fully edentulous patients or in posterior sites of partially edentulous patients. These indications clearly represent the majority of implant patients. In esthetic sites, a submerged approach is utilized to satisfy the specific esthetic demands. The possibility to successfully utilize short implants (6 and 8 mm) and a reduced healing period of 3 months are further advantages of ITI implants due to favorable properties of the rough TPS surface. With the introduction of the microrough SLA surface, a reduction of the healing period to 6 weeks facilitates further progress towards simplification of implant therapy. In summary, the ITI Dental Implant System represents a scientifically well-documented, complete implant system for the treatment of fully and partially edentulous patients, offering straightforward surgical concepts based on predictable treatment outcome and excellent cost-effectiveness.

Anisotropic elastic properties of cancellous bone from a human edentulous mandible.

Abstract: The elastic moduli have not been reported for cancellous bone from the edentulous mandible. Accurate values are needed for finite element modeling of the mandible. The aim of this study was to determine elastic modulus values in three orthogonal directions for cancellous bone taken from an edentulous jaw and to relate these values to apparent density and volume fraction. Seven samples were obtained from the edentulous mandible of a 74-year-old female. Young's modulus was determined by compression testing of cubes cut with the faces aligned with the anatomic axes. Bone volume fraction averaged 0.33 (SD 0.14) and apparent density averaged 0.55 g/cc (SD 0.29). Young's modulus was greatest in the mesio-distal direction (mean 907 MPa, SD 849 MPa), followed by the bucco-lingual (mean 511 MPa, SD 565 MPa) and infero-superior direction (mean 114 MPa, SD 78 MPa). The infero-superior direction was less than the bucco-lingual (P = 0.03) and mesio-distal (P = 0.002). The mesio-distal and bucco-lingual directions could not be shown to be different (P = 0.32). This suggests a model of transverse isotropy for cancellous bone in the jaw, where the symmetry axis is along the infero-superior (weakest) direction.

Alternative to the median region of the palate for placement of an orthodontic implant.

Abstract: Tooth-borne anchorage may be one of the greatest limitations of modern orthodontic treatment, because teeth move in response to forces. Previous investigators have placed temporary implants in the median-sagittal palate in order to establish maximum anchorage. This area, however, may be characterized by relatively low vertical bone support. The aim of this study was therefore to find an alternative palatal implant site which offers a higher amount of bone support. This study comprised 22 patients wishing for maximum anchorage underwent presurgical diagnostic evaluation by means of low-dose dental CT. The measuring results regarding vertical bone volume and the position of the neighbouring tooth roots were used as the basis for further treatment. The statistical data analysis indicated an area suitable for implant placement in the group of patients examined. This area was located 6 to 9 mm posterior to the incisive foramen and 3 to 6 mm paramedian, under avoidance of the mid-palatal suture. The patients showed such a great range of variation in vertical bone volume that a preoperative diagnostic evaluation also seems to be recommendable when very short implants are used in order to avoid perforations of the lower nasal duct.

A 5-year prospective study of Astra single tooth implants.

Abstract: Aim— To evaluate the AstraTech Implant ST (Molndal, Sweden) for single tooth replacement clinically and radiographically after 5 years in function. Subjects and method— Fifteen patients (age range 16 to 48) with missing maxillary anterior teeth (6 central incisors, 8 laterals, 1 bicuspid) had four 13 mm and eleven 15 mm single tooth implants provided. All patients were seen at 4- to 6-monthly intervals for oral hygiene maintenance. Periapical radiographs using Rinn holders and a long cone technique were taken at the crown insertion and after 1 year, 3 and 5 years. Results— No implant losses were observed in 14 of the 15 patients available for evaluation. No abutment screw loosening or soft tissue problems were observed. At crown insertion the mean bone level was 0.46±0.55 to 0.48 ±0.56 mm apical to the top of the implant neck and there were no statistically significant changes in the radiographic bone level over the 5 years of the study (0.36±0.37 to 0.43±0.46 mm at year 5). One crown was recemented after 18 months in function and 1 crown was replaced because of a fracture to the porcelain incisal edge. Conclusion— The Astra Tech Implants ST were highly successful in single tooth replacement and bone levels during 5 years of function were stable. Resume Le but de cette etude a ete d'evaluer cliniquement et radiologiquement le systeme Astra Tech Implant ST pour le remplacement d'une dent, apres cinq annees en fonction. Quinze patients de seize a 48 ans avec une dent anterosuperieure manquante (six incisives centrales, huit laterales et une premolaire) ont ete implantes avec quatre implants de 13 mm et onze de 15 mm. Tous les patients ont ete revus a des intervalles de quatre a six mois pour l'entretien de l'hygiene buccale. Des radiographies periapicales utilisant la methode de Rinn avec long cone ont ete prises lors de l'insertion de la couronne et apres une, trois et cinq annees. Aucune perte implantaire n'a ete observee pour quatorze parmi les quinze patients. Aucune vis de l'implant ne s'est devissee et aucun probleme de tissus mous n'a ete observe. Lors du placement de la couronne, le niveau osseux moyen etait de 0.46±0.55 a 0.48 ±0.56 mm apicalement par rapport au sommet du col de l'implant. Il n'y avait aucune variation statistiquement significative pour les niveaux osseux radiographiques durant les cinq ans a la fin desquels ces mesures etaient respectivement de 0.36±0.37 a 0.43 ±0.46 mm. Une couronne a ete rescellee apres 18 mois. Une autre a ete remplacee suite a une fracture du bord incisif en porcelaine. Le systeme implantaire Astra Tech ST s'est revele excellent pour le remplacement unitaire, les niveaux osseux durant les cinq annees de fonction sont restes stables. Zusammenfassung Ziel: Das Astra Tech Implantat ST (Molndal Sweden) uber einen Zeitraum von 5 Jahren in Funktion klinisch und radiologisch zu untersuchen. Material und Methode. 15 Patienten (Alter zwischen 16 und 48) mit fehlenden Zahnen in der Oberkieferfront (6 zentrale Inzisiven, 8 laterale Inzisiven, 1 Pramolar) wurden vier 13 mm und elf 15 mm lange Einzelimplantate eingesetzt. Alle Patienten wurden alle 4 bis 6 Monate nachkontrolliert und die Mundhygiene uberwacht. Nach dem Einsetzen der Kronen und 1 Jahr, 3 und 5 Jahre nach dem Einsetzen der Kronen wurden periapikale Rontgenaufnahmen mit dem Filmhaltern des Rinnsystems und der Langtubustecknik aufgenommen. Resultate: Bei den 14 von insgesamt 15 Patienten, welche nachuntersucht werden konnten, war kein Implantatverlust zu verzeichnen. Es konnten keine lockeren Schrauben bei den Prothetikaufbauten und keine Probleme an den Weichgeweben beobachtet werden. Beim Einsetzen der Kronen lag das Knochenniveau 0.46±0.55 bis 0.48±0.56 mm apikal vom Oberteil des Implantathalses und es fanden wahrend der 5 Jahre dauernden Beobachtungszeit keine statistisch signifikanten Veranderungen im radiologischen Knochenniveau statt (0.36±0.37 bis 0.43±0.46 mm nach 5 Jahren). Eine Krone musste nach 18 Monaten in Funktion rezementiert und eine Krone wegen einer Porzellanfraktur der Inzisalkante ersetzt werden. Schlussfolgerung: Die Astra Tech Implantate ST waren fur den Einzelzahnersatz sehr erfolgreich und die Knochenniveaus waren wahrend der Beobachtungszeit von 5 Jahren in Funktion stabil. Resumen Intencion— Evaluar clinica y radiograficamente el implante Astra Tech ST (Molndal Suecia) para sustitucion de diente unico tras 5 anos en function. Sujetos y metodo− 15 pacientes (rango de edad de 16 a 48) con ausencia de dientes maxilares anteriores (6 incisivos centrales, 8 laterales, 1 bicuspide) recibieron cuatro implantes unitarios de 13 mm y once de 15 mm. Todos los pacientes fueron vistos con intervalos de 4 a 6 meses para mantenimiento de higiene oral. Se tomaron radiografias periapicales usando soportes Rinn y tecnica de cono largo en el momento de insercion de la corona y al ano, 3 y 5 anos. Resultados— No se observaron perdidas de implantes en 14 de los 15 pacientes disponibles para la evaluacion. No se observaron movilidades en los pilares o problemas de los tejidos blandos. En el momento de insertion de la corona el nivel medio de hueso fue de 0.46±0.55 a 0.48±0.56 mm apical de la parte alta del cuello del implante y no hubo cambios estadisticamente significativos en el nivel radiografico de hueso a lo largo de los 5 anos del estudio (0.36±0.37 a 0.43±0.46 mm en el quinto ano). Una corona se recemento despues de 18 meses en funcion y una corona se sustituyo por fractura de la porcelana en el borde incisai. Conclusion— Los implantes Astra Tech ST fueron altamente exitosos en la sustitucion de dientes unitarios y los niveles de hueso a los 5 anos se mantuvieron estables.

Surgical procedures in partially edentulous patients with ITI implants.

Abstract: Today, partially edentulous patients represent the majority of patients seeking treatment with implant-supported prostheses. This chapter presents the specific aspects of the surgical handling of partially edentulous patients with either single-tooth gaps, extended edentulous spaces or distal extension situations. Due to differences in treatment objectives, a distinction is made between sites without esthetic priority (non-esthetic sites) and with esthetic priority (esthetic sites). In non-esthetic sites, the primary goal of the surgical therapy is to achieve a predictable hard and soft tissue integration of the implant to re-establish function with the implant-supported prosthesis. In esthetic sites, the goal of surgical therapy is to achieve successful tissue integration and to obtain esthetic soft tissue contours to re-establish both function and esthetics. Therefore, the surgeon must have a clear understanding of the specific needs in a given situation, and must master the necessary surgical techniques concerning a correct implant placement and a correct soft tissue handling to achieve the treatment objectives. In non-esthetic sites, a non-submerged approach is clearly preferred, thus avoiding a second-stage procedure for abutment connection. If a soft tissue correction is necessary to re-establish keratinized peri-implant mucosa, this is done at the time of implant placement with mucogingival surgery. In esthetic sites, a submerged implant placement is preferred to achieve esthetically pleasing soft tissue contours. If a soft tissue augmentation is necessary, this is done at the time of implant placement with connective tissue grafts. Thus, the second surgical procedure after 8-10 weeks of healing is reduced to a mucosaplasty like a punch biopsy, avoiding an open flap procedure. Based on favorable properties of the TPS surface, short implants (6 or 8 mm) and short healing periods of 3-4 months have been successfully utilized in partially edentulous patients in the last 14 years. The introduction of the SLA surface allows a further reduction of the healing period to 6 weeks of healing in all sites with normal bone density (class I-III). In summary, the ITI philosophy offers straightforward surgical concepts to predictably achieve the treatment objectives with the least demanding surgical protocol, reducing the related chairtime and costs for the patient and the clinician.

Histological observations on biopsies harvested following sinus floor elevation using a bioactive glass material of narrow size range.

Abstract: We evaluated the bone augmenting capacity of bioactive glass particles, size range 300-355 microns (BG-particles), in human sinus floor elevations using histomorphometrical methods. A total of 10 patients underwent bilateral grafting, using a 1:1 mixture of autogenous bone particles (from iliac crest) and BG-particles at one side (experimental side), and bone particles only at the other side (control side, split mouth design). A total of 72 bone biopsies were taken at the time of fixture installation; that is, 3 patients at 4 months, 3 at 5 months and 3 at 6 months after grafting and 1 patient at 16 months (when she presented again). In each case 6 biopsies were taken, 3 left and 3 right. Histomorphometry showed that in grafts at control sides, trabecular bone was present after 4 months, comprising almost 41% of the tissue volume. This bone contained viable osteocytes and was of mature lamellar type and showed a mature histological appearance. Bone volume continued to increase slightly, to 42% at 5 months, 44% at 6 months and 45% at 16 months. The graft volume at experimental sides consisted at 4 months for 28% of woven and some lamellar bone, and increased to 35% at 5 months and 38% at 6 months, when mainly lamellar bone was found. At 16 months a lamellar bone volume of 45% was found. The BG-particles transformed and became excavated with time, starting at 4 months, and their centers gradually filled with bone tissue. All BG-particles had disappeared by resorption at 16 months after grafting and had been replaced by bone tissue. Parameters of bone turnover (% osteoid surface, % resorption surface, mineral apposition rate as measured by tetracycline labeling) indicated that bone remodeling was very active at both sides, during more than 6 months, despite the mature histological appearance of the bone tissue. From these histological observations, we conclude that a 1:1 mixture of autogenous bone/BG-particles seems a promising alternative to autogenous bone only, when low amounts of bone tissue are available for sinus augmentation.

Diagnostic characteristics of clinical and microbiological tests for monitoring periodontal and peri‐implant mucosal tissue conditions during supportive periodontal therapy (SPT)

Abstract: The aim of this study was to evaluate a clinical and a microbiological test for monitoring tissue condition during supportive periodontal therapy (SPT) and to compare their diagnostic characteristics at implant and tooth sites. Twelve female (age: 37-72 years) and 7 male patients (age: 26-83 years) were evaluated in this study on the basis of availability to follow a rigid SPT program. Patients had received a complete periodontal examination at 1 and 5 years after implant placement. This included standardized radiographs obtained at implants and matching control teeth. One implant site and one tooth site per patient were followed during the last 2 years of the SPT program. At each recall visit microbiological samples were analyzed according to DNA/RNA analysis identifying periodontal pathogens (IAI Pado Test 4.5, Institute for Applied Immunology, Zuchwil, Switzerland). Presence or absence of bleeding on probing at these sites was also noted using a standardized probing force of 0.25 N (Audio Probe, ESRO, Thalwil ZH, Switzerland). The percentage number of recall visits with positive bacteriological test results and positive BOP scores were calculated. Disease progression at the sites was defined if the annual increase in probing depth was > or = 0.5 mm/year (2.5 mm in 5 years) or if the annual decrease in CADIA values (Computer Assisted Densitometric Image Analysis) was more than -0.7 per year (-3.5 in 5 years). Changes below these values were considered as negative test results indicating stability of the sites. The diagnostic characteristics (sensitivity, specificity, positive and negative predictive values) of BOP and microbiological tests alone or in combination were then calculated using two-by-two tables. By application of increasing thresholds of BOP frequencies set for definition of positive test outcome (BOP > or = 10% > or = 20% > or = 25% > or = 50% > or = 75% > or = 90% or the combined BOP > or = 75%, but DNA positive > or = 10%, > or = 25% > or = 34% > or = 50% > or = 67% > or = 90%) receiver operator characteristics curves (ROC) were constructed for teeth and implants. The areas under the ROC curves were calculated and compared by means of chi-square tests. The results indicated statistically significant better diagnostic characteristics of both tests at implants compared to teeth. The inclusion of an additional microbiological test significantly enhanced the diagnostic characteristics of BOP alone at teeth as well as at implants.

The scientific basis for and clinical experiences with Straumann implants including the ITI Dental Implant System: a consensus report.

Abstract: Successful endosseous implant therapy requires integration of the implant with bone, soft connective tissue and epithelium. This report from a consensus conference on Straumann dental implants including the ITI Dental Implant System documents the interaction of these nonsubmerged one-piece implants with the oral tissues and reviews clinical studies supporting the high success achievable with these implants in patients. Light and electron microscopy reveal that epithelial structures similar to teeth are found around the implants. A connective tissue zone exists between the apical extension of the junctional epithelium and the alveolar bone. This connective tissue comprises a dense circular avascular zone of connective tissue fibers surrounded by a loose vascular connective tissue. The histologic dimensions of the epithelium and connective tissue comprising the biologic width are similar to the same tissues around teeth. The nonsubmerged one-piece design of the Straumann implants, which have been used for over 20 years, has set a standard in implant dentistry, with other implants now being manufactured and placed using similar techniques. Straumann implants have an endosseous portion that is either coated with a well-characterized and well-documented titanium plasma-sprayed surface or is sandblasted and acid attacked. Both surfaces have been shown to have advantages for osseous integration compared to machined and other smoother implant surfaces. These advantages include greater amounts of bone-to-implant contact, more rapid integration with bone tissue, and higher removal torque values. The lack of component connection at or below the alveolar crest provides additional benefits. Component connection at the alveolar crest, as seen with submerged implants, results in microbial contamination, crestal bone loss and a more apical epithelial location. Numerous human clinical trials document the successful use of Straumann implants in a variety of indications and areas of the mouth. These include prospective long-term trials using strict criteria of success and life table analyses. Taken together, the clinical studies reveal that Straumann implants can be used predictably in partially edentulous and completely edentulous maxilla and mandibles with high success rates. Furthermore, the animal and microscopic studies reviewed provide a scientific basis for the integration of Straumann implants with bone, connective tissue and epithelium.

A controlled clinical trial of implant-retained mandibular overdentures: 10 years' results of clinical aspects and aftercare of IMZ implants and Brånemark implants.

Abstract: The aim of this prospective randomized controlled clinical trial was to evaluate the clinical outcomes and prosthetic aftercare of edentulous patients with a mandibular overdenture retained by two IMZ implants or two Branemark implants during a 10-year period. Patients were allocated to the IMZ group (n=29) or the Branemark group (n=32) by a computerized balancing method. In the IMZ group, four implants were lost during the 10-year follow-up (survival rate: 93%). In the Branemark group, nine implants were lost (survival rate: 86%). All patients were re-operated successfully. Multiple prosthetic revisions were necessary in both groups; especially the precision attachment system in the overdenture (23% of the total number of revisions) and the denture base and teeth (26% of the total number of revisions) were subject to frequent fracture. From this study, it can be concluded that both the IMZ implant and the Branemark implant systems supporting an overdenture are functioning well after 10 years of follow-up. There are no indications of a worsening of clinical or radiographical state after 10 years.

A histological evaluation of TiO2-gritblasted and Ca-P magnetron sputter coated implants placed into the trabecular bone of the goat: Part 2.

Abstract: The aim of this study was to investigate the synergetic influence of surface topography and chemical composition of oral implant materials on bone response. For the experiment screw designed implants were used. The implants were grit-blasted with TiO2 particles. The implants were left uncoated (Ti) or provided with three different amorphous/crystalline Ca-P magnetron sputter coatings, resp. 0.1 μm (CaP-0.1), 1 μm (CaP-1) and 4 μm (CaP-4), in thickness. The implants were inserted in the medial femoral condyles of 12 goats. Each femur received 2 implants. After implantation periods of 6 and 12 weeks the implants were retrieved and prepared for histological and histomorphometrical evaluation (bone contact and bone mass). The light microscopy revealed that bone response to CaP-4 and CaP-1 implants was similar. For example, after 12 weeks, screw threads were almost completely covered with bone. In contrast to CaP-0.1 and Ti implants, where bone apposition was less pronounced. Histomorphometry demonstrated that the bone-to-implant contact for the CaP-1 and CaP-4 implants was significantly higher (P<0.05) than for the CaP-0.1 and Ti implants. This difference existed already after 6 weeks and was even enhanced after 12 weeks. The bone mass measurements revealed that only at 12 weeks CaP-4 implants had significantly more bone contact inside the screw threads than non-coated Ti-implants (P<0.05). Supported by our findings, we conclude that the additional application of a 1–4 μm thick Ca-P magnetron sputter coating can further improve the healing response to surface roughened oral implants placed into trabecular bone.

Effects of titanium surfaces blasted with TiO2 particles on the initial attachment of cells derived from human mandibular bone. A scanning electron microscopic and histomorphometric analysis.

Abstract: This study was performed to determine the effect of commercially pure titanium surfaces blasted with TiO2 particles on the biological responses of cells derived from human mandibular bone The morphology and attachment of those cells were investigated on turned titanium surfaces (control) and surfaces blasted with 45 μm (standard), 45–63 μm, and 63–90 μm TiO2 particles The surfaces were analyzed in a scanning electron microscope Based on surface analyses reported elsewhere, the turned samples had the smoothest surfaces and the roughest were those blasted with the largest particles (63–90 μm) The cell profile areas were measured using a semi-automatic interactive image analyzer The attachment was determined as a ratio of the area of cell profiles and the total micrograph area and was expressed as percentage of attachment Morphologically, the cells were heterogeneous In general, the cells had spread well on all titanium surfaces, indicating good attachment to both smooth and rough surfaces After 1, 3 and 6 h, the percentage of cell attachment did not differ significantly between the surfaces blasted with 63–90 μm and the turned surfaces, but was significantly lower on the surfaces blasted with 45 μm or 45–63 μm particles After 24 h the surfaces blasted with 63–90 μm particles had a higher rate of cell attachment than all the other surfaces including the controls It is concluded that attachment and growth of cells originating from human mandibular bone in vitro, are influenced by the micro-texture of the implant surface

A prospective split-mouth comparative study of two screw-shaped self-tapping pure titanium implant systems.

Abstract: Clinical data indicate different medium and long-term outcomes of endosseous implants for different implant configurations and in particular implant surfaces. The present study compares 2 very similar implant systems but with different surface characteristics in a split-mouth-randomized design. The Astra-Tech (A) system (Astra-Tech AB, Molndal, Sweden) consisted of selftapping TiO2-blasted screw-shaped implants made of commercially pure titanium, and the Branemark (B) System (Nobel Biocare, Gothenburg, Sweden) comprised selftapping Mark II implants with machined surface irregularities. Throughout the 2-years' observation period, no significant differences could be found concerning probing depths, presence of plaque or change in marginal bone level. A statistically significant difference in location of the marginal bone level in relation to the shoulder of the implant was found in favor of the A system both at baseline and after 2 years. Cumulative success rates of 100% (A) and 97.7% (B) were not statistically different. From a prosthetic point of view, more soldering points were needed for A compared to B to reach clinical acceptable fit. More years of observation are needed to compare the fate of the soft and hard tissues surrounding two different implant surfaces.

Prosthetic management of the partially dentate patient with fixed implant restorations

Abstract: The aim of this chapter is to discuss the current prosthetic management of the partially dentate patient by means of fixed implant restorations in the scope of the ITI(R) Dental Implant System. For that purpose, the related statements defined by the participants of the prosthodontic section of the 1997 ITI Consensus Conference in Vitznau, Switzerland, will be presented, completed by explanatory comments where appropriate. Distinct conceptual differences will be made between the esthetic zone (areas of the dental arches where esthetic considerations are of primary concern) and the non-esthetic zone (regions of the jaws where esthetic aspects do not represent a priority), and between single tooth replacement and multiple unit implant restorations. Furthermore, it is underlined that current clinical concepts should be based on both predictable treatment outcome and cost-effectiveness. In this context, a straightforward surgical and prosthetic protocol is generally preferred in posterior locations of the oral cavity, using a nonsubmerged implant placement comprising an easily accessible implant shoulder location, and subsequently cemented implant restorations, basically according to a traditional prosthodontic approach. In esthetically demanding indications, where normally a distinctly submucosal implant shoulder location is advocated, screw-retained restorations are preferred, based on prefabricated prosthetic components (e.g. machined cast-on copings) to assure optimum surface properties and contour, and to achieve adequate marginal adaptation.

Effect of microgrooved poly-l-lactic (PLA) surfaces on proliferation, cytoskeletal organization, and mineralized matrix formation of rat bone marrow cells

Abstract: Previous experiments showed that microgrooved substrate surfaces can influence the in vitro behavior of osteoblast-like rat bone marrow (RBM) cells Cellular morphology and matrix deposition can be directed by substrate chemistry and topography RBM cells cultured on poly-l-lactic acid (PLA) exhibit increased mineralization and alkaline phosphatase activity compared to polystyrene substrates Consequently, the purpose of the present in vitro study is to further evaluate the behavior of RBM cells on microgrooved (groove depth 05 to 15 microns, groove and ridge width 1 to 10 microns) polystyrene (PS) and PLA surfaces Besides grooved, also smooth control surfaces were made Our results confirmed that microtextured surfaces are capable of influencing the behavior of the osteoblast-like RBM cells in vitro Microtopography did not influence the RBM proliferation rate, or cellular actin organization However, confocal laser scanning microscopy showed that cellular attachment is dependent on the applied material Also clear differences were found between textured PS and PLA, with regard to the calcium content We therefore conclude, that the application of microtextures could possibly influence the bone regeneration around biodegradable PLA devices

Public awareness, information sources and evaluation of oral implant treatment in Norway

Abstract: A nation-wide survey from a representative sample of the general Norwegian population was made in co-operation with Statistics of Norway, to assess public awareness, sources of information and evaluation of oral implants. A response rate of 70.8% was obtained. Of the general population 70.1% (95% confidence interval: 68.6-71.6%) had heard of oral implants. No specific demographic variables were associated with unawareness of oral implants. Of the general population 60.4% (95% confidence interval: 57.9-62.8%) evaluated oral implants positively and 56.7% (95% confidence interval: 54.7%-58.7%) would consider oral implants as treatment for themselves if needed, while 18.0% gave negative evaluation and 23.0% would not consider implant treatment. Logistic regression analyses indicated that young males in urban areas with high income and high educational level were most positive to oral implants. News media like newspapers and TV/radio were together with personal communications the most frequently indicated sources of information. News media were associated with negative evaluation of implants. The overall positive evaluation of oral implants suggests however that the Norwegian general public utilises several sources of information, and are able to evaluate them critically.

Pulsed electromagnetic fields promote bone formation around dental implants inserted into the femur of rabbits.

Abstract: The present study examined the effect of applying a pulsed electromagnetic field (PEMF) on bone formation around a rough-surfaced dental implant. A dental implant was inserted into the femur of Japanese white rabbits bilaterally. A PEMF with a pulse width of 25 microseconds and a pulse frequency of 100 Hz was applied. PEMF stimulation was applied for 4 h or 8 h per day, at a magnetic intensity of 0.2 mT, 0.3 mT or 0.8 mT. The animals were sacrificed 1, 2 or 4 weeks after implantation. After staining the resin sections with 2% basic fuchsin and 0.1% methylene blue, newly formed bone around the implant on tissue sections was evaluated by computer image analysis. The bone contact ratios of the PEMF-treated femurs were significantly larger than those of the control groups. Both the bone contact ratio and bone area ratio of the 0.2 mT- and 0.3 mT-treated femurs were significantly larger than the respective value of the 0.8 mT-treated femurs (P < 0.001). No significant difference in bone contact ratio or bone area ratio was observed whether PEMF was applied for 4 h/day or 8 h/day. Although a significantly greater amount of bone had formed around the implant of the 2-week treated femurs than the 1-week treated femurs, no significant difference was observed between the 2-week and 4-week treated femurs. These results suggest that PEMF stimulation may be useful for promoting bone formation around rough-surfaced dental implants. It is important to select the proper magnetic intensity, duration per day, and length of treatment.

Within-subject comparison of maxillary long-bar implant-retained prostheses with and without palatal coverage: patient-based outcomes.

Abstract: Although maxillary implant overdentures are used in oral rehabilitation, different designs have not been compared previously in clinical trials. This crossover trial was designed to measure differences in patient satisfaction with maxillary long-bar implant overdentures with and without palatal coverage opposed by a fixed mandibular implant-supported prosthesis. Data were also gathered on new conventional dentures and on maxillary conventional dentures opposed by mandibular fixed prostheses. Sixteen participants were selected from a population wearing conventional dentures. Fifteen received new upper and lower dentures (1 drop-out). Four implants were placed in the maxilla and mandible (2 drop-outs). A mandibular fixed prosthesis was inserted in 13 participants, who were then divided into 2 groups. One group (n = 7) received long-bar overdentures with palate, then long-bar overdentures without palate. The other group (n = 6) received the same treatments in the reverse order. Mastication tests and psychometric evaluations using Visual Analog Scales and Categorical Scales were performed throughout the study. General satisfaction was very high with both maxillary implant-supported prostheses, as were ratings of almost all psychosocial and functional variables. There were no significant differences between treatments, suggesting that patients are equally satisfied with long-bar overdentures with and without palate when these are opposed by mandibular fixed prostheses. However, the ratings given to the maxillary implant prostheses were not significantly higher than for new conventional maxillary prostheses. This suggests that maxillary implant prostheses should not be considered as a general treatment of choice in patients with good bony support for maxillary conventional prostheses.