La survie implantaire suite à une réhabilitation par mise en charge immédiate d’une prothèse totale mandibulaire reliée à deux implants non jumelés : une étude pilote expérimentale

Problématique : Les connaissances théoriques et pratiques au sujet de la mise en charge immédiate d’implants non jumelés chez les édentés sont limitées. Objectifs : Cette étude avait pour but de : (1) déterminer le taux de survie implantaire de 2 implants non jumelés supportant une prothèse totale mandibulaire suite à une mise en charge immédiate, (2) évaluer les changements des niveaux osseux et de stabilité implantaire survenus sur ces 2 implants durant une période de 4 mois et les comparer à un implant témoin, et (3) décrire les complications cliniques associées à ce mode de mise en charge. Méthodologie : Chez 18 individus édentés (âge moyen de 62±7 ans), cette étude de phase I avec un design pré/post a évalué les résultats cliniques suivant la mise en charge immédiate (<48 heures) de 2 implants non jumelés par une prothèse totale mandibulaire. À l’aide de radiographies périapicales, de sondages osseux et d’analyses de la fréquence en résonnance, les niveaux osseux péri-implantaires (en mm) et les niveaux de stabilité implantairte (en ISQ) de ces 2 implants insérés dans la région parasymphysaire ont été évalués à la chirurgie (T0) et au suivi de 4 mois (T1). Un implant non submergé et sans mise en charge inséré dans la région de la symphyse mandibulaire a été utilisé comme témoin. Les données ont été analysées avec des modèles mixtes linéaires, la méthode de Tukey ajustée, l’analyse de variance de Friedman et des tests de rang signés de Wilcoxon. Résultats : De T0 à T1, 3 implants mis en charge immédiatement ont échoué chez 2 patients. Le taux de survie implantaire obtenu était donc de 91,7% (33/36) et, par patient, de 88,9% (16/18). Aucun implant témoin n’a échoué. Les changements osseux documentés radiologiquement et par sondage autour des implants mis en charge immédiatement étaient, respectivement, de -0,2 ± 0,3 mm et de -0,5 ± 0,6 mm. Les pertes d’os de support implantaire n’ont pas été démontrées statistiquement différentes entre les implants avec mise en charge immédiate et les témoins. Les niveaux moyens de stabilité implantaire ont augmenté de 5 ISQ indépendamment de la mise en charge. Les niveaux moyens d’ISQ n’ont pas été démontrés statistiquement différents entre les implants avec mise en charge immédiate et les témoins à T0 ou T1. Cinq des 18 patients n’ont expérimenté aucune complication clinique, alors que 9 en ont eu au moins deux. Hormis les échecs implantaires, aucune de ces complications n’a entraîné de changements au protocole. Conclusion : Les résultats à court terme suggèrent que : (1) le taux de survie implantaire suite au protocole immédiat est similaire à ceux rapportés lors d’un protocole de mise en charge conventionnel (2) les changements d’os de support implantaire et de stabilité ne sont pas différents comparativement à ceux d’un implant témoin, (3) un niveau élevé d’expérience clinique et chirurgicale est requis pour effectuer les procédures et pour gérer les complications associées. Ces résultats préliminaires devraient être confirmés dans une étude clinique de phase II.

Does immediate loading affect clinical and patient-centered outcomes of mandibular 2-unsplinted-implant overdenture? : a 2-year within-case analysis

Objective To provide 2-year clinical- and patient-oriented data with regard to mandibular overdenture assisted by 2 immediately loaded unsplinted implants. Material and methods In this pre-post design, Phase-I clinical trial, 18 edentate individuals (62.4 ± 7.7 years) received a new set of complete denture. Then, following standard procedures, 3 threaded implants (OsseoSpeed TX™, Dentsply Implants, Mölndal, Sweden) were placed in the mandible in each patient, and locator abutments (Zest Anchors LLC, Escondido, U.S.A.) were inserted on the right and left side implants. The midline implant served as a control for within-patient comparison. The immediate loading was conducted within 24 h of surgery. Data were collected at baseline (T0), 12 (T1) and 24 (T2) months after immediate loading. The clinical outcomes included implant survival rate, crestal bone level changes and implant stability. These criteria were assessed through clinical and radiographic examinations as well as resonance frequency analysis. Patient-centered outcomes included patient satisfaction and oral health-related quality of life measured using validated questionnaires. Brunner-Langer approach was used for statistical analysis. Results Implant survival rate for immediate loaded implants was 91.7% at 2-year follow-up. None of the unloaded implants failed. There was no statistically significant difference at baseline and follow-ups with regard to clinical outcomes between loaded and unloaded implants. Patient satisfaction and quality of life improved (p < 0.0001) from baseline to 2-year follow-up. Conclusion Immediate loading protocol did not negatively affect clinical outcomes, satisfaction and quality of life of patients wearing 2-unsplinted-implant mandibular overdenture for 2 years. This conclusion requires confirmation by randomized control trials. Clinical significance statement Mandibular overdenture assisted by two immediately-loaded unsplinted implants is successful treatment based on 2-year clinical and patient-based outcomes.

Does immediate loading affect clinical and patient-centered outcomes of mandibular 2-unsplinted-implant overdenture? : a 2-year within-case analysis

Objective To provide 2-year clinical- and patient-oriented data with regard to mandibular overdenture assisted by 2 immediately loaded unsplinted implants. Material and methods In this pre-post design, Phase-I clinical trial, 18 edentate individuals (62.4 ± 7.7 years) received a new set of complete denture. Then, following standard procedures, 3 threaded implants (OsseoSpeed TX™, Dentsply Implants, Mölndal, Sweden) were placed in the mandible in each patient, and locator abutments (Zest Anchors LLC, Escondido, U.S.A.) were inserted on the right and left side implants. The midline implant served as a control for within-patient comparison. The immediate loading was conducted within 24 h of surgery. Data were collected at baseline (T0), 12 (T1) and 24 (T2) months after immediate loading. The clinical outcomes included implant survival rate, crestal bone level changes and implant stability. These criteria were assessed through clinical and radiographic examinations as well as resonance frequency analysis. Patient-centered outcomes included patient satisfaction and oral health-related quality of life measured using validated questionnaires. Brunner-Langer approach was used for statistical analysis. Results Implant survival rate for immediate loaded implants was 91.7% at 2-year follow-up. None of the unloaded implants failed. There was no statistically significant difference at baseline and follow-ups with regard to clinical outcomes between loaded and unloaded implants. Patient satisfaction and quality of life improved (p < 0.0001) from baseline to 2-year follow-up. Conclusion Immediate loading protocol did not negatively affect clinical outcomes, satisfaction and quality of life of patients wearing 2-unsplinted-implant mandibular overdenture for 2 years. This conclusion requires confirmation by randomized control trials. Clinical significance statement Mandibular overdenture assisted by two immediately-loaded unsplinted implants is successful treatment based on 2-year clinical and patient-based outcomes.

Mechanical Testing of Indirect Composite Materials Directly Applied on Implant Abutments

Purpose: To test the strength to failure and fracture mode of three indirect composite materials directly applied onto Ti-6Al-4V implant abutments vs cemented standard porcelain-fused-to-metal (PFM) crowns. Materials and Methods: Sixty-four locking taper abutments were randomly allocated to four groups and were cleaned in ethanol in an ultrasonic bath for 5 min. After drying under ambient conditions, the abutments were grit blasted and a custom 4-cusp molar crown mold was utilized to produce identical crowns (n = 16 per group) of Tescera (Bisco), Ceramage (Shofu), and Diamond Crown (DRM) according to the manufacturer`s instructions. The porcelain-fused-to-metal crowns were fabricated by conventional means involving the construction and a wax pattern and casting of a metallic coping followed by sintering of increasing layers of porcelain. All crowns were loaded to failure by an indenter placed at one of the cusp tips at a 1 mm/min rate. Subsequently, fracture analysis was performed by means of stereomicroscopy and scanning electron microscopy. One-way ANOVA at 95% level of significance was utilized for statistical analysis. Results: The single load to failure (+/- SD) results were: Tescera (1130 +/- 239 N), Ceramage (1099 +/- 257 N), Diamond Crown (1155 +/- 284 N), and PFM (1081 +/- 243 N). Stereomicroscopy analysis showed two distinct failure modes, where the loaded cusp failed either with or without abutment/metallic coping exposure. SEM analysis of the fractures showed multiple crack propagation towards the cervical region of the crown below a region of plastic deformation at the indenter contact region. Conclusion: The three indirect composites and PFM systems fractured at loads higher than those typically associated with normal occlusal function. Although each material had a different composition and handling technique, no significant differences were found concerning their single load to fracture resistance among composite systems and PFM.

Geosynthetic Reinforced Soil for Low-Volume Bridge Abutments, January 2012

This report presents a review of literature on geosynthetic reinforced soil (GRS) bridge abutments, and test results and analysis from two field demonstration projects (Bridge 1 and Bridge 2) conducted in Buchanan County, Iowa, to evaluate the feasibility and cost effectiveness of the use of GRS bridge abutments on low-volume roads (LVRs). The two projects included GRS abutment substructures and railroad flat car (RRFC) bridge superstructures. The construction costs varied from $43k to $49k, which was about 50 to 60% lower than the expected costs for building a conventional bridge. Settlement monitoring at both bridges indicated maximum settlements ≤1 in. and differential settlements ≤ 0.2 in transversely at each abutment, during the monitoring phase. Laboratory testing on GRS fill material, field testing, and in ground instrumentation, abutment settlement monitoring, and bridge live load (LL) testing were conducted on Bridge 2. Laboratory test results indicated that shear strength parameters and permanent deformation behavior of granular fill material improved when reinforced with geosynthetic, due to lateral restraint effect at the soilgeosynthetic interface. Bridge LL testing under static loads indicated maximum deflections close to 0.9 in and non-uniform deflections transversely across the bridge due to poor load transfer between RRFCs. The ratio of horizontal to vertical stresses in the GRS fill was low (< 0.25), indicating low lateral stress on the soil surrounding GRS fill material. Bearing capacity analysis at Bridge 2 indicated lower than recommended factor of safety (FS) values due to low ultimate reinforcement strength of the geosynthetic material used in this study and a relatively weak underlying foundation layer. Global stability analysis of the GRS abutment structure revealed a lower FS than recommended against sliding failure along the interface of the GRS fill material and the underlying weak foundation layer. Design and construction recommendations to help improve the stability and performance of the GRS abutment structures on future projects, and recommendations for future research are provided in this report.

Modified Sheet Pile Abutments for Low-Volume Road Bridges, January 2012

To date there have been few investigations of the substructures in low-volume road (LVR) bridges. Steel sheet piling has the potential to provide an economical alternative to concrete bridge abutments, but it needs investigation with regard to vertical and lateral load resistance, construction methods, and performance monitoring. The objectives of this project were to develop a design approach for sheet pile bridge abutments for short-span low-volume bridges, formulate an instrumentation and monitoring plan to evaluate performance of sheet pile abutment systems, and understand the cost and construction effort associated with building the sheet pile bridge abutment demonstration project. Three demonstration projects (Boone, Blackhawk, and Tama Counties) were selected for the design, construction, and monitoring of sheet pile abutments bridges. Each site was unique and required site-specific design and instrumentation monitoring. The key findings from this study include the following: (1) sheet pile abutment bridges provide an effective solution for LVR bridges, (2) the measured stresses and deflection were different from the assumed where the differences reflect conservatism in the design and the complex field conditions, and (3) additional research is needed to optimize the design.

Modified Sheet Pile Abutments for Low-Volume Road Bridges: Tech Transfer Summary, January 2012

Iowa has about 22,936 bridges on low-volume roads (LVRs). Based on the National Bridge Inventory data, 22 percent of the LVR bridges in Iowa are structurally deficient, while 5 percent of them are functionally obsolete. The substructure components (abutment and foundation elements) are known to be contributing factors for some of these poor ratings. Steel sheet piling was identified as a possible long-term option for LVR bridge substructures; but, due to lack of experience, Iowa needed investigation with regard to vertical and lateral load resistance, construction methods, design methodology, and load test performance. This project was initiated in January 2007 to investigate use of sheet pile abutments. *************Tech Transfer Summary. For full report see: http://publications.iowa.gov/id/eprint/14832*************

Evaluation of Concrete Sealers for Use on Bridge Pier Tops and Abutments, R-242, 1971

Many reports have been written concerning investigations of concrete sealants. The primary concern of most investigators is the protection of bridge decks from de-icing chemicals which cause surface scaling and, when allowed to permeate to reinforcing steel, result in deep spalling and general concrete deterioration. The problem of protecting abutments and pier tops from salt solutions entails a significantly different approach than the problem of protecting bridge decks. The epoxy resins become eligible as a protective material since one need not be concerned with slipperiness or its abrasive characteristics. Protection with linseed oil at regular intervals would prove bothersome because of the inaccessibility of pier tops after the deck is placed. The primary purpose of this investigation was to evaluate various commercial products in terms of their ability to prevent concrete scaling of bridge abutments and pier tops which are subject to salt water deterioration.

Field Monitoring of Curved Girder Bridges with Integral Abutments, TPF-5(169), 2014

Nationally, there are questions regarding the design, fabrication, and erection of horizontally curved steel girder bridges due to unpredicted girder displacements, fit-up, and locked-in stresses. One reason for the concerns is that up to one-quarter of steel girder bridges are being designed with horizontal curvature. There is also an urgent need to reduce bridge maintenance costs by eliminating or reducing deck joints, which can be achieved by expanding the use of integral abutments to include curved girder bridges. However, the behavior of horizontally curved bridges with integral abutments during thermal loading is not well known nor understood. The purpose of this study was to investigate the behavior of horizontal curved bridges with integral abutment (IAB) and semi-integral abutment bridges (SIAB) with a specific interest in the response to changing temperatures. The long-term objective of this effort is to establish guidelines for the use of integral abutments with curved girder bridges. The primary objective of this work was to monitor and evaluate the behavior of six in-service, horizontally curved, steel-girder bridges with integral and semi-integral abutments. In addition, the influence of bridge curvature, skew and pier bearing (expansion and fixed) were also part of the study. Two monitoring systems were designed and applied to a set of four horizontally curved bridges and two straight bridges at the northeast corner of Des Moines, Iowa—one system for measuring strains and movement under long term thermal changes and one system for measuring the behavior under short term, controlled live loading. A finite element model was developed and validated against the measured strains. The model was then used to investigate the sensitivity of design calculations to curvature, skew and pier joint conditions. The general conclusions were as follows: (1) There were no measurable differences in the behavior of the horizontally curved bridges and straight bridges studied in this work under thermal effects. For preliminary member sizing of curved bridges, thermal stresses and movements in a straight bridge of the same length are a reasonable first approximation. (2) Thermal strains in integral abutment and semi-integral abutment bridges were not noticeably different. The choice between IAB and SIAB should be based on life – cycle costs (e.g., construction and maintenance). (3) An expansion bearing pier reduces the thermal stresses in the girders of the straight bridge but does not appear to reduce the stresses in the girders of the curved bridge. (4) An analysis of the bridges predicted a substantial total stress (sum of the vertical bending stress, the lateral bending stress, and the axial stress) up to 3 ksi due to temperature effects. (5) For the one curved integral abutment bridge studied at length, the stresses in the girders significantly vary with changes in skew and curvature. With a 10⁰ skew and 0.06 radians arc span length to radius ratio, the curved and skew integral abutment bridges can be designed as a straight bridge if an error in estimation of the stresses of 10% is acceptable.

A Generalized Model Study of Scour Around Bridge Piers and Abutments, HR-24, 1953

Four classes of variables are apparent in the problem of scour around bridge piers and abutments--geometry of piers and abutments, stream-flow characteristics, sediment characteristics, and geometry of site. The laboratory investigation, from its inception, has been divided into four phases based on these classes. In each phase the variables in three of the classes are held constant and those in the pertinent class are varied. To date, the first three phases have been studied. Typical scour bole patterns related to the geometry of the pier or abutment have been found. For equilibrium conditions of scour with uniform sand, the velocity of flow and the sand size do not appear to have any measurable effects on the depth of scour. This result is especially encouraging in the search for correlation between model and prototype since it would indicate that, primarily, only the depth of flow might be involved in the scale effect. The technique of model testing has been simplified, therefore, because rate of sediment transportation does not need to be scaled. Prior to the establishment of equilibrium conditions, however, depths of scour in excess of those for equilibrium conditions have been found. A concept of active scour as an imbalance between sediment transport capacity and rate of sediment supply has been used to explain the laboratory observations.

Scour Around Bridge Piers and Abutments, HR-30 and Iowa Highway Research Board Bulletin No. 4, 1956

Man’s never-ending search for better materials and construction methods and for techniques of analysis and design has overcome most of the early difficulties of bridge building. Scour of the stream bed, however, has remained a major cause of bridge failures ever since man learned to place piers and abutments in the stream in order to cross wide rivers. Considering the overall complexity of field conditions, it is not surprising that no generally accepted principles (not even rules of thumb) for the prediction of scour around bridge piers and abutments have evolved from field experience alone. The flow of individual streams exhibits a manifold variation, and great disparity exists among different rivers. The alignment, cross section, discharge, and slope of a stream must all be correlated with the scour phenomenon, and this in turn must be correlated with the characteristics of the bed material ranging from clays and fine silts to gravels and boulders. Finally, the effect of the shape of the obstruction itself-the pier or abutment-must be assessed. Since several of these factors are likely to vary with time to some degree, and since the scour phenomenon as well is inherently unsteady, sorting out the influence of each of the various factors is virtually impossible from field evidence alone. The experimental approach was chosen as the investigative method for this study, but with due recognition of the importance of field measurements and with the realization that the results must be interpreted so as to be compatible with the present-day theories of fluid mechanics and sediment transportation. This approach was chosen because, on the one hand, the factors affecting the scour phenomenon can be controlled in the laboratory to an extent that is not possible in the field, and, on the other hand, the model technique can be used to circumvent the present inadequate understanding of the phenomenon of the movement of sediment by flowing water. In order to obtain optimum results from the laboratory study, the program was arranged at the outset to include a related set of variables in each of several phases into which the whole problem was divided. The phases thus selected were : 1. Geometry of piers and abutments, 2. Hydraulics of the stream, 3. Characteristics of the sediment, 4. Geometry of channel shape and alignment.

Field Testing of Integral Abutments, Interim Report, HR-399, 1998

Integral abutment bridges are constructed without an expansion joint in the superstructure of the bridge; therefore, the bridge girders, deck, abutment diaphragms, and abutments are monolithically constructed. The abutment piles in an integral abutment bridge are vertically orientated, and they are embedded into the pile cap. When this type of a bridge experiences thermal expansion or contraction, horizontal displacements are induced at the top of the abutment piles. The flexibility of the abutment piles eliminates the need to provide an expansion joint at the inside face to the abutments: Integral abutment bridge construction has been used in Iowa and other states for many years. This research is evaluating the performance of integral abutment bridges by investigating thermally induced displacements, strains, and temperatures in two Iowa bridges. Each bridge has a skewed alignment, contains five prestressed concrete girders that support a 30-ft wide roadway for three spans, and involves a water crossing. The bridges will be monitored for about two years. For each bridge, an instrumentation package includes measurement devices and hardware and software support systems. The measurement devices are displacement transducers, strain gages, and thermocouples. The hardware and software systems include a data-logger; multiplexers; directline telephone service and computer terminal modem; direct-line electrical power; lap-top computer; and an assortment of computer programs for monitoring, transmitting, and management of the data. Instrumentation has been installed on a bridge located in Guthrie County, and similar instrumentation is currently being installed on a bridge located in Story County. Preliminary test results for the bridge located in Guthrie County have revealed that temperature changes of the bridge deck and girders induce both longitudinal and transverse displacements of the abutments and significant flexural strains in the abutment piles. For an average temperature range of 73° F for the superstructure concrete in the bridge located in Guthrie County, the change in the bridge length was about 1 118 in. and the maximum, strong-axis, flexural-strain range for one of the abutment piles was about 400 micro-strains, which corresponds to a stress range of about 11,600 psi.

Bacterial adhesion efficiency on implant abutments: a comparative study

The attachment of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 28213 onto six different materials used to manufacture dental implant abutments was quantitatively determined after 2 and 24 h of contact between the materials and the bacterial cultures. The materials were topographically characterized and their wettability determined, with both parameters subsequently related to bacterial adhesion. Atomic force microscopy, interferometry, and contact angle measurement were used to characterize the materials" surfaces. The results showed that neither roughness nor nano-roughness greatly influenced bacterial attachment whereas wettability strongly correlated with adhesion. After 2 h the degree of E. coli attachment markedly differed depending on the material whereas similar differences were not observed for S. aureus, which yielded consistently higher counts of adhered cells. Nevertheless, after 24 h the adhesion of the two species to the different test materials no longer significantly differed, although on all surfaces the numbers of finally adhered E. coli were higher than those of S. aureus

Use of checkerboard DNA-DNA hybridization to evaluate the internal contamination of dental implants and comparison of bacterial leakage with cast or pre-machined abutments

To evaluate the checkerboard DNA-DNA hybridization method for detection and quantitation of bacteria from the internal parts of dental implants and to compare bacterial leakage from implants connected either to cast or to pre-machined abutments. Nine plastic abutments cast in a Ni-Cr alloy and nine pre-machined Co-Cr alloy abutments with plastic sleeves cast in Ni-Cr were connected to Branemark-compatible implants. A group of nine implants was used as control. The implants were inoculated with 3 mu l of a solution containing 10(8) cells/ml of Streptococcus sobrinus. Bacterial samples were immediately collected from the control implants while assemblies were completely immersed in 5 ml of sterile Tripty Soy Broth (TSB) medium. After 14 days of anaerobic incubation, occurrence of leakage at the implant-abutment interface was evaluated by assessing contamination of the TSB medium. Internal contamination of the implants was evaluated with the checkerboard DNA-DNA hybridization method. DNA-DNA hybridization was sensitive enough to detect and quantify the microorganism from the internal parts of the implants. No differences in leakage and in internal contamination were found between cast and pre-machined abutments. Bacterial scores in the control group were significantly higher than in the other groups (P < 0.05). Bacterial leakage through the implant-abutment interface does not significantly differ when cast or pre-machined abutments are used. The checkerboard DNA-DNA hybridization technique is suitable for the evaluation of the internal contamination of dental implants although further studies are necessary to validate the use of computational methods for the improvement of the test accuracy. To cite this article:do Nascimento C, Barbosa RES, Issa JPM, Watanabe E, Ito IY, Albuquerque Junior RF. Use of checkerboard DNA-DNA hybridization to evaluate the internal contamination of dental implants and comparison of bacterial leakage with cast or pre-machined abutments.Clin. Oral Impl. Res. 20, 2009; 571-577.doi: 10.1111/j.1600-0501.2008.01663.x.

Deformation of Implant Abutments After Framework Connection Using Strain Gauges

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)