Stud Attachments Research Articles

Root-retained overdentures: Part I—biomechanical and clinical aspects

Despite recent developments in dental impiantology, the conservative approach to root preservation is still valid. In view of increased root caries rate in the elderly and lax oral hygiene habits of most overdenture wearers, placing protective copings on root abutments, when economically feasible, is the preferred method of treatment. Retention of overdentures is increased by including stud attachments in the abutments. Incorporation of cast metal frameworks is recommended to prevent base fractures.

支台歯の動揺度と維持力に関する実験的研究

Using a cone-type stud attachment, the relationship between mobility of the abutment tooth and retentive force was experimentally evaluated. Changing the thickness of artificial periodontium and pressure (load) on the retainer, retentive force was electrically recorded. Retentive force (F), retentive time (T) and impulse (I), were measured on it.The following results were obtained;1. For the cone-type denture retainer, the retentive force was highly affected with the magnitude of the load in the abutment with thin periodontium (P=0.0123).2. Both of retentive force (F) and Impulse (I) decreased with increase of periodontal thickness (P<0.0001).3. Within the range of 1.5mm to 6.0mm thickness of the periodontium, the thicker the periodontium was, the lager a retention bearing index of the abutment tooth (I/F ratio) we found it became (P<0.0001).4. It was suggested that Impulse (I) might represent a total amount of retentive force to be born by the abutment, and that I/F ratio would be available for planning the RPD, particularly in evaluating the optimal retentive force.

Removable Partial Overdentures with Mechanical (Precision) Attachments

Mechanical attachments for overdentures have been available in various forms for over a century. The explosive interest in osseointegration and the effort on the part of the profession to avoid the complete denture as a treatment modality has stirred the interest in positive retentive elements for overdentures represented by the mechanical stud and bar attachments. The cited references provide a resource as a trouble-free guide in the selection and use of the various stud and bar attachment systems. The clinical examples show a pattern of application not generally discussed by the manufacturers, illustrating the simplicity of use with the options for all attachments including magnets. The discussion on magnets comes from 9 years of clinical experience. Rare earth magnets provide excellent adjunct retention, and their assembly follows the same protocol and complexity as stud attachment systems. All magnets, at the present state of the art, have a corrosion potential with the exception of the Laser Sealed Units (Golden Dental, Golden, CO). Finally, the mechanics of the attachment overdenture serves as an excellent training field for the osseointegrated prosthesis, be it the classic Brånemark (Nobelpharma USA, Chicago, IL) restorative or the implant overdenture concept.

Laboratory-made stud attachment. Report II. Effect of cycle of engaging and disengaging on fatigue

A number of engaging and disengaging of retainers induce those fatigue and consequent decrease in retentive force. In this study on the laboratory-made stud attachment consisting of a male (Type IV gold) like a snap and a female with semi-loop and linear portion made by bending a wrought gold wire, the maximum buldges of males, the distances between the female tips, and the retentive forces were measured before and after each stage of engaging and disengaging of predetermined cycles (10: initial, 1, 000, 3, 000, 5, 000, 10, 000). The males had 0.25 mm undercut. The females were 0.8mm in diameter and 3, 5, 7 and 10mm in length from the contact points with the males at the semi-loop portion to the points fixed in the resin base at the linear portion.Results:1. The initial retentive force, the abrasion of male, the permanent deformation of female and the decrease in retentive force all increased with the shorter female.2. 5mm-length female kept the most amount of retentive force of approximately 380 to 190g during 1, 000 to 10, 000 cycles.

Attractive forces of Sm-Co magnet systems for stud attachment.

The magnetic characteristics of various magnetic systems utilizing a Sm-Co magnet were examined. The attractive force became significantly larger by pairing two magnets or housing the magnet with ferromagnetic yoke. As the gap between the magnet and keeper increased however, the attractive force was rapidly decreased, and when the gap exceeded 0.5mm, it became almost the same as those of the single magnet systems or unhoused magnets. Although the housing effect of the half-shallowed yoke was reduced by half when no gap existed, the attractive force with this yoke became larger than that of the full-size yoke when the gap was 0.2mm or more.The magnetic systems composed of a pair of magnets or a magnet housed with the full-size yoke may be superior when the system components are closely arranged, while the use of the shallower yoke may be more favorable in retention and ease of clinical application, when a larger gap is inevitably introduced.

Ｆｕｌｌ ｏｖｅｒｄｅｎｔｕｒｅのそしゃく力，そしゃく力リズムおよびそしゃく力量に関する研究 下がく両側犬歯歯根周囲麻酔下における検討

Recently in dental treatment, various considerations apply the function of living tissue are exerted all possible efforts. Especially in prosthetic cases on remaining a few tooth without extraction, overdenture is reconsiderd new merits. It is supported that one of the advantage is the use of mechanoreceptor of periodontal ligament. Though, there is no reports that conclude it enough.Accordingly, observing the effect of the mechanoreceptor of periodontal ligament on the masticatory function in full overdenture used “O'ring” stud attachments on bilateral mandibular canines, the author studies on the masticatory force under anesthesia with “semi-conductor”. As the results of these studies, the author arrived at the following conclusions.1. The masticatory forces under anesthesia were larger than in normal, and there was a tendency that these increase from 1st masticatory period to 4th. The increasing rate was highest in the ham.2. The rhythm of masticatory forces under anesthesia were slower than in normal, and there was a tendency that these increase from 1st masticatory period to 4th. And yet in the ham, such tendency weakened rapidly.3. The integrated amounts of masticatory forces under anesthesia were smaller than in normal.From these studies, it was given a suggestion that under anesthesia the full overdenture wearers masticated more strongly than in normal. Though, the duration was short and the integrated amounts of masticatory forces were little. So, under anesthesia the full overdenture wearers did not masticate efficiently and rhythmically. It is inferred that such reason is the lack of information from the mechanoreceptor of periodontal ligament under anesthesia. Therefore it was estimated the use of remaining the roots in full overdenture.

Sm-Co 合金磁石を用いた根面アタッチメントの臨床例 : 第 2 報 磁石の被覆法について

Sasaki and Kinouchi (1976) reported on a stud attachment using the Sm-Co alloy magnet and Pd-Co-Ni alloy for casting. Since self-curing resin was used as the coating material for this magnet, magnetism is weakened and exposure of the magnet makes rusting easy. Therefore, 4-META resin was used to make the coating on the magnet thin and uniform. When waxing up a root cap, an acrylic plate was used to make the surface smooth and flat. These modifications assure reliable magnetism and prevention of rusting. The details are described in the text.

Sm-Co 合金磁石を用いた根面アタッチメントの臨床例 : 義歯の側方維持について

The magnetic retention stud attachments using the Sm-Co magnets and the Pd-Co-Ni magnetic casting alloy were developed by Sasaki and Kinouchi in 1976. the retentiveness of the attachments for the denture dislocating action was recognized, but lower resistance to the denture rotation and side shift was also recognized. The metal coping was designed to have a tenon and the capping a mortise and vice versa, to achieve the bracing effect necessary as the indirect retainer. The results were good for denture retention and stability, but some problems remain in the technical procedure.

Photoelastic stress analysis of overdenture attachments

This is a summary of various investigations designed to study the transmission of forces through overdenture abutments to the remaining oral structures: 1. The best design for uniform distribution of occlusal forces to the remaining structures was the conventional design, particularly the amalgam restored abutment. This design, however, provided less effective retention and stability than the other designs. 2. In the group of stud type attachments studied, the Ancrofix transferred stress in a more favorable manner to the remaining structures in the oral cavity when compared to the other stud attachments. 3. The Hader Bar provided more desirable effects to the abutments and remaining structures than did the other tissue bars. 4. The major objective in the choice of an overdenture attachment should be the consideration of how the stress is transferred from these attachments through the abutments and other structures, not the retnetion and stability.

Occlusal force transmission by overdenture attachments

This investigation utilized a composite photoelastic model to examine the load-transfer characteristics of several overdenture attachments. Tissue bar (Hader and King Connector) and stud (extracoronal) attachments (Rotherman, Gerber, and Ancrofix) were studied. The following observations may provide guidelines for the selection of overdenture attachments. 1. The more retentive tissue bar and extracoronal attachments produced higher stress concentrations. 2. Of the tissue bars tested, the Hader Bar produced less torquing forces on the abutment teeth. 3. The Ancrofix appeared to share the forces of occlusion between abutments and the posterior edentulous regions. 4. It must be emphasized that several other factors will also influence the choice of overdenture attachments, such as the judgment of the dentist, economics with respect to the patient, and the availability of laboratory expertise.

The Stud Attachment Overlay Denture and Proprioception

A procedure for fabricating stud attachments for use on mandibular teeth has been developed. The retention of two or more isolated mandibular roots for use with an overlay denture will preserve tooth proprioception, which is one of the major determinants of masticatory function. The use of an overlay denture in specific instances offers a better physiologic result than does the extraction of all the teeth. A procedure for fabricating stud attachments for use on mandibular teeth has been developed. The retention of two or more isolated mandibular roots for use with an overlay denture will preserve tooth proprioception, which is one of the major determinants of masticatory function. The use of an overlay denture in specific instances offers a better physiologic result than does the extraction of all the teeth.