Relation between attractive force and keeper surface characteristics of iron-neodymium-boron magnetic attachment systems.
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The purpose of this study was to evaluate the influence of heating, cast bonding, and subsequent polishing procedures on attractive force of magnetic attachments. Two magnetic attachment systems with keepers of different chemical compositions (Hicorexslim 3013, 447J1; Magfit EX400, AUM20) were employed. Keepers examined were: (1) untreated; (2) heated; (3) cast-bonded with Ag-Pd alloy; (4) cast-bonded with Ag-Pd alloy and polished; (5) cast-bonded with gold alloy; and (6) cast-bonded with gold alloy and polished. Attractive force was determined with a force gauge, and surface structure was evaluated with scanning laser and electron microscopes. Attractive force of the Hicorex system was reduced by cast bonding, whereas that of the Magfit system was reduced by both heating and cast bonding. However, attractive force of both systems was somewhat recovered through the polishing process. Based on the findings of this study, it was suggested that careful polishing after cast bonding was indispensable to the recovery of attractive force for both attachment systems. (+info)
Treatment of severely mutilated incisors: a challenge to the pedodontist.
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Dental caries is the single most common chronic childhood disease. In early childhood caries, there is early carious involvement and gross destruction of the maxillary anterior teeth. This leads to difficulty in speech, decreased masticatory efficiency, development of abnormal tongue habits and subsequent malocclusion and psychological problems if esthetics are compromised. The restoration of severely decayed primary incisors is often a difficult procedure that presents a special challenge to pediatric dentists. This case report documents the restoration of severely mutilated lateral incisors in a patient with early childhood caries. (+info)
Mechanical versus chemical retention for restoring complex restorations: what is the evidence?
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This article reports the findings from a study conducted to answer this research question: can adhesive resin liners provide retention that is the same as dentinal pins or pots and slots when restoring complex amalgam restorations? The study methodology consisted of two components: a review of the literature and a survey to assess methods and materials that general practitioners use in their clinical practice for restoring complex amalgam restorations. Even though a vast majority of the general practitioners surveyed reported using dentinal pins or pots and slots, the occurrence or frequency of use was under 50 percent. It was also reported from the survey that over half the respondents are using adhesive resin liners exclusively when restoring complex restorations. New and improved materials allow general practitioners to restore complex restorations without the risks associated with the placement of pins or pots and slots. A review of the available literature indicates that adhesive resin liners may be used as an alternative or adjunct to mechanical retention. Because of the improvements of bonding strength of adhesive resin liners, dentinal pins and pots and slots should not be the only methods considered when faculty assist students in the development of treatment plans for patients who need complex amalgam restorations. (+info)
Clinical assessment of primary stability of endosseous implants placed in the incisor region, using resonance frequency analysis methodology: an in vivo study.
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AIM: To evaluate the effect of immediate loading on the primary stability of endosseous implants placed in the anterior incisor region by mapping the stability, using resonance frequency analysis, over a period of time. MATERIALS AND METHODS: A total of eight implants (Zimmer Screw-Vent) were placed in four patients. The Osstell resonance frequency analyzer was used to determine the primary stability at baseline (day 1), 15 th day, 30 th day, 60 th day, and 90 th day for each of the eight implants. Analysis of data was done using SPSS (Statistical Package for Social Science; version 4.0.1). RESULTS: All implants showed adequate initial stability at baseline with an ISQ > 50. Implant nos. 1, 3, 4, 7, and 8 showed a high initial stability at baseline (ISQ > 65), following which a decrease in the stability was recorded during the 15 th day, 30 th day, and 60 th day. By the 90 th day, the stability values were nearly equivalent to those obtained at baseline. The highest mean stability value was recorded on the day of implant placement. The lowest mean stability recording was obtained on the 30 th day after implant osteotomy. By the 90 th day, the mean stability value was nearly equivalent to that obtained at baseline. CONCLUSIONS: Within the limitations of this study, it can be concluded that immediate loading of implants placed in the maxillary and mandibular incisor region does not seem to have an adverse effect on the osseointegration of implants, which achieved a high primary stability. The use of the resonance frequency analyzer as a tool to monitor the variation in the stability of the implants over a period of time has been validated. (+info)
A newly designed resonance frequency analysis device for dental implant stability detection.
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Resonance frequency (RF) analysis technology was used to design a new dental implant stability detector. To calibrate and test the performance of this novel apparatus, in vitro and in vivo models, respectively, were used. The RF values of the test implants detected using our new device and a commercially available analogous device (Osstell) were compared. Further, implant stability status was also detected clinically using our device at 2, 4, 8, and 12 weeks after surgery. A high correlation was demonstrated between the values measured with the two devices (y = 0.31x-12.45; R2 = 0.98, p < 0.05). In our clinical tests, an initial RF value above 10.0 kHz indicated that the implant was ready to accept functional loading, while values in the 4.0-10.0 kHz range reflected the need for further osseointegration. In conclusion, these results indicated that our new device might be useful in a clinical setting for evaluating the healing status of a placed implant. (+info)
Galvanic corrosion of ferritic stainless steels used for dental magnetic attachments in contact with an iron-platinum magnet.
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This study was an examination of the galvanic corrosion of ferritic stainless steels, namely SUS 444, SUS XM27, and SUS 447J1, in contact with a Fe-Pt magnet. The surface area ratio of each stainless steel to the Fe-Pt magnet was set at 1/1 or 1/10. Galvanic corrosion between the stainless steels and the magnet was evaluated by the amount of released ions and the electrochemical properties in 0.9% NaCl solution. Although each stainless steel showed sufficient corrosion resistance for clinical use, the amount of ions released from each tended to increase when the stainless steel was in contact with the magnet. When the surface area ratio was reduced to 1/10, the amount of Fe ions released from the stainless steels increased significantly more than when there was no contact. Since contact with the magnet which possessed an extremely noble potential created a very corrosive environment for the stainless steels, 447J1 was thus the recommended choice against a corrosion exposure as such. (+info)
Retentive force of pure titanium konus telescope crowns fabricated using CAD/CAM system.
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The purpose of this study was to investigate the clinical application possibility of pure titanium konus telescope crowns fabricated using a CAD/CAM system. For the CAD/CAM system, Dental Cadim (Advance Co.) was used. For the material, exclusive pure titanium block for this system was used in this experiment. Two types of experimental dies with different heights assumed the konus inner crown and three types of konus outer crowns with different gap widths at the occlusal part were prepared. The outer crown was seated on the inner crown die, and a load was applied perpendicularly to the upper surface of the outer crown for 10 seconds. Pullout test was performed at a crosshead speed of 5 mm/min, and the retentive force was measured. With increase in the height of the inner crown die and the applied load, the retentive force of konus telescope crown increased. Similarly, as the gap width at the occlusal part between the inner crown die and outer crown increased, the retentive force of konus telescope crown also increased. (+info)
Galvanic corrosion between dental precious alloys and magnetic stainless steels used for dental magnetic attachments.
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In this study, we examined the corrosion behavior of dental precious alloys and magnetic stainless steels, namely SUS 444, SUS XM27, and SUS 447J1, used for dental magnetic attachments. Their galvanic corrosion behavior was evaluated from the viewpoint of corrosion potentials when they were in contact with each other. Rest potentials of the precious alloys were constantly higher than those of magnetic stainless steels. Since most gold alloys raised the corrosion potential more significantly than silver alloys did, silver alloys seemed to be better suited than gold alloys for combination with magnetic stainless steels. However, all corrosion potential values were sufficiently lower than the breakdown potentials of the stainless steels and existed within their passive regions. Based on the findings of this study, SUS XM27 and SUS 447J1--which exhibited higher breakdown potentials than SUS 444--emerged as the preferred choices for combination with gold alloys. (+info)