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The gradual loss of retention and the need for periodic replacement of attachment-system components are the most frequent complications in implant-supported overdentures.The purpose of this in vitro study was to develop a new attachment system for overdentures with polymeric materials and compare its retention and deformation with a conventional O-ring attachment system.A matrix with 2 mini-implants with ball abutments was used to simulate the mandibular border during a fatigue resistance test. A total of 60 polyacetal (n=20), polytetrafluoroethylene (n=20), and conventional O-ring (n=20) attachments were captured in pairs with acrylic resin and subjected to 3625 insertion and removal cycles, simulating 30 months of overdenture use. The internal and external deformations of the attachments were assessed using an optical stereomicroscope. One-way ANOVA and the Tukey honestly significant difference tests were used for statistical evaluation (α=.05).The polyacetal attachment system showed the highest retention (P.001), followed by the O-ring and polytetrafluoroethylene attachments. The O-ring attachments exhibited the lowest deformation (P.001), and the polyacetal attachments had the highest internal deformation (P.001).The newly developed polyacetal attachment model increased the retention of mini-implant-retained overdentures, and despite the deformation experienced, the retention period appears to be better than that of conventional systems.

Patients with ectodermal dysplasia have abnormalities of 2 or more structures that originate from the ectoderm. The oral manifestations often include the congenital absence of teeth and malformed teeth. This clinical report describes the interdisciplinary care from childhood through the definitive dental rehabilitation completed at skeletal maturation to replace the missing teeth in a patient with ectodermal dysplasia. Treatment began at 9 years of age with an implant-assisted mandibular overdenture to improve function and replace the missing mandibular teeth. Orthodontic treatment for the consolidation of space, composite resin restorations, and interim removable dental prostheses were provided to improve esthetics and replace the missing maxillary teeth. Skeletal growth was monitored, and orthognathic surgery was performed at the cessation of growth. The definitive rehabilitation consisted of a mandibular fixed dental prosthesis supported by dental implants and a maxillary removable dental prosthesis to restore the patient to esthetics and function.

Statement of problem Artificial markers called fiducials are commonly used to orient digitized surfaces for analysis. However, when these markers are tangible and placed in the region of interest, they may alter surface topography and influence data analysis. Purpose The purpose of this in vitro study was to apply a modified digital surface fitting method based on anatomic landmarks to evaluate denture accuracy and to use 2 different denture processing techniques to evaluate the method. The goal was to noninvasively measure and describe any surface differences in denture processing techniques at the intaglio and denture tooth levels. Material and methods Twenty standardized maxillary complete dentures were waxed on standardized edentulous casts and processed by using acrylic resin compression (COM, n=10) and injection molding (INJ, n=10) methods. Digital scans were recorded of the anatomic surface of the cast, the intaglio and cameo surfaces of the acrylic resin dentures, and the cameo surface of the wax dentures. Three anatomic fiducials were identified on denture intaglio and cast scans and 4 on the cameo surfaces of waxed and acrylic resin denture scans. These fiducials were then used to digitally align the anatomic with the processed intaglio surfaces and the waxed with the processed cameo surfaces. Surface displacements were compared among processed dentures expressed at specific points (9 tissue landmarks and 8 tooth landmarks). The accuracy of surface displacements was assessed by changes in the number and location of anatomic fiducials. The scanning precision and the intraobserver repeatability in the selection of dental landmarks were also determined. For each landmark, the spatial (x, y, and z) mean differences between the 2 processing techniques were calculated for the intaglio and the cameo surfaces and presented on each orthogonal plane. Statistical nonparametric comparison of these means was analyzed with the Mann-Whitney U test (α=.05). Benjamini-Hochberg corrections for multiple comparisons were used. Results Changing the number and the location of anatomic landmarks had a small effect on the precision of the surface fitting. Repeated scans yielded high precision levels. In contrast, intraobserver repeatability had a larger error. In general, injection-molded dentures showed less displacement after polymerization than did the compression-molded ones. These differences were more substantial at the denture tooth level than on the intaglio surfaces. Conclusions Anatomic noninvasive fiducials chosen at distinct locations of maxillary edentulous areas seem to be reliable markers for the superposition of corresponding digital surface scans. Maxillary dentures processed with the injection molding technique have minimal deformation. Posterior denture teeth displace in 3 dimensions with the compression molding technique.

The coexistence of a skeletal class III deformity and partial edentulism poses a clinical challenge and requires a comprehensive evaluation followed by a multidisciplinary approach. This clinical report presents the integrated management of a class III malocclusion in a 50-year-old woman with partial edentulism. The patient received adjunctive orthodontic treatment with a rigid temporary anchorage device, a Le Fort I maxillary osteotomy, and prosthodontic rehabilitation with removable maxillary copings, an overdenture, and a mandibular partial removable dental prosthesis with precision attachments.

Implant angulation should be considered when selecting an attachment. Some in vitro studies have investigated the relationship between implant angulation and changes in the retention force of the stud attachment, but few studies have evaluated the effect of cyclic loading and repeated cycles of insertion and removal on the stud attachment.The purpose of this in vitro study was to evaluate the effects of implant angulation on the retentive characteristics of overdentures with 2 different stud attachments, an experimental system and O-rings in red and orange, after cyclic loading and repeated insertion and removal cycles.The canine region of a mandibular experimental model was fitted with 2 implant fixtures with 2 different stud attachment systems at implant angulations of 0, 15, or 30 degrees. A mastication simulator was used to simulate cyclic loading, and a universal testing machine was used to evaluate retentive force changes after repeated insertion and removal cycles. To simulate the numbers of mastication and insertion and removal cycles per annum, 400000 cyclic loadings and 1080 insertion and removal cycles were performed. Wear patterns and attachment surface deformations were evaluated by scanning electron microscopy. Data were analyzed using the Kruskal-Wallis test, Mann-Whitney U test with Bonferroni correction (α=.05/3=.017), and the paired-sample Student t test (α=.05).When retentive forces before and after testing were compared, O-ring showed significant retention loss at all implant angulations (P.001). In contrast, the experimental system showed little retention loss in the 0- and 15-degree models (P.05), whereas the 30-degree model showed a significant increase in retentive force (P=.001). At all implant angulations, retention loss increased significantly for the orange O-ring, followed by the red O-ring, and the experimental system (P.001). Scanning electron microscopy analysis showed more intense wear in the matrix than the patrix (abutment that matches to matrix) and more severe wear and deformation of the O-ring rubber matrix than of the experimental zirconia ball.Upon completion of the experiment, wear and deformation were found for all attachment systems. Even when implants are not installed in parallel, the experimental system can be used without involving great loss of retention.

Statement of problem Attachments for mandibular overdentures may not allow for adequate freedom of rotation. Purpose The purpose of this study was to subject 3 commonly used stud types of resilient attachments to rotation and to measure and compare the degree of rotation that occurs before the attachments bind. Material and methods Three stud attachments (ERA, Locator Extended Range, O-Ring System) with their corresponding metal housings were evaluated, first for a single implant system and secondly for a 2-attachment parallel implant system for the mandibular arch. Both the manufacturers' most and least retentive components were tested in each system. In the Locator system, the medium retention (3 lbs) for the standard is the most retentive of the extended range. A total of 60 test specimens, 5 per group, were fabricated. The attachments were connected to a 115-mm rod and attached to a testing device composed of a base, implant analogs, and a vertical plate holding graph paper. A free-sliding plastic block, which supported the metal rod parallel to the base, was removed to release the rod. The distance the rod fell was photographed and input into a computer with software designed to measure linear movement. Three-way ANOVA with heteroscedasticity consistent standard errors was used for data analyses (α=.05). Results Significant differences found among the most retentive components showed that the Locator had a greater freedom of rotation than the ERA ( P =.001). The most retentive components in all systems showed that 1 attachment had a greater freedom of rotation than 2 ( P =.005). When testing the least retentive components, all systems were significantly different ( P Locator Extended Range > ERA. For all 3 systems, the least retentive components showed the most freedom ( P ≤.008). Conclusions The least retentive components offer greater rotation than the most retentive components for all attachment systems tested and for both single and double attachments. Using the most retentive components, the Locator Extended Range attachment allows greater rotation than does the ERA for both single and double attachments. Using the least retentive components, the ORS attachment allows the most rotation and ERA the least for both single and double attachments. Using the most retentive components, one attachment allows greater rotation than does 2 attachments for the attachment systems evaluated.

Occlusal devices are a valid treatment modality in certain clinical situations. For an occlusal device to be effective, sufficient retention and stability should be derived from coverage of the occlusal and incisal surfaces of the teeth. In the absence of most or all of the posterior teeth, the effectiveness of the device could become compromised as the incisal portions of the anterior teeth are typically not conducive to adequately retaining and stabilizing the device. This clinical report describes an approach to improving the retention and stability of an occlusal device for a patient with shortened dental arches by use of the patient's existing extracoronal attachments.

Recurrent or chronic dislocation of the temporomandibular joint is relatively rare and often results in facial asymmetry, impairment of function, and discomfort. Although manual reduction is the primary choice of treatment, patients presenting with recurrent or prolonged dislocations require conservative and surgical methods to limit forward movement of the mandibular condyle. This clinical report presents a 75-year-old woman with severe mandibular deviation and subsequent facial asymmetry caused by a chronic unilateral temporomandibular joint dislocation that was treated with a mandibular guidance prosthesis combined with physical therapy. (J Prosthet Dent 2008;99:95-100)

Cherubism is an early childhood disease that primarily involves the mandible and consists of painless mandibular enlargement with or without maxillary involvement and progresses rapidly over the course of several years. This clinical report describes the fabrication of maxillary fixed partial dentures and a mandibular overdenture for a 21-year-old man with cherubism.

International audience; It is now possible to provide combination fixed/removable prosthetic restorations using only 1 dental alloy, such as CoCr, a nonprecious alloy. This alloy offers clinical performance and demonstrated corrosion resistance. This clinical report demonstrates use of a single CoCr alloy for metal-ceramic fixed partial dentures in conjunction with a mandibular removable partial denture.

Statement of problem Fiber-reinforced composite inlay fixed partial dentures (FRCIFPDs) may be a reliable prosthetic solution. Clinical procedures involved in their fabrication have been defined, but little is known about their mechanical behavior. Purpose This in vitro study used the finite element (FE) method to investigate 3-dimensional (3-D) stress and strain distribution produced in a 3-unit FRCIFPD. Material and methods A 3-D FE model (227,768 3-D tetrahedral elements) of a 3-unit FRCIFPD cemented onto box-shaped prepared teeth was developed. Stress and strain distribution generated by a maximum load of 196 N applied vertically or laterally to the FRCIFPD centrally, on an area of 4 ± 0.1 mm 2 , was analyzed. The specimen used to acquire the geometry of the model was also used for mechanical compressive tests, with vertical and lateral loads, to validate the numerical model. Results The peak values of stress, calculated on the outer and inner surfaces of the FRCIFPD, were localized in the connector areas. When a vertical load was applied, stress on the prepared teeth was concentrated at the cervical margin of the abutment preparation. Conclusion Within the limitations of this in vitro study, the results suggest that within the FRCIFPD, stress concentrates at the connector areas, and that in the prepared teeth, peak stress is at the cervical margin of the box of the preparation.

This clinical report describes the prosthetic rehabilitation of a maxillary defect with an obturator retained by extracoronal resilient attachments. Resin-bonded cast-metal units were used to retain and stabilize the obturator through abutment contour modification, addition of retentive elements, and primary abutment splinting. The resulting rehabilitation conserved tooth structure and satisfied both esthetic and functional needs.

Statement of problem. There are no studies that analyze the long-term durability of minimally invasive fixed partial dentures (FPDs) by comparing different methods of adhesive bonding. Purpose. This in vitro study examined the influence of cavity design and operative technique on the marginal adaptation of resin-bonded composite FPDs. Material and methods. Slot-inlay tooth preparations with cavity margins located in enamel were prepared in 18 maxillary canines and 18 maxillary first molars designated as abutments. The specimens were divided equally into 3 experimental groups. In all groups, butt joint tooth preparations were created in canines and molars. In group 2, canines were prepared additionally with a 1.5-mm wide palatal bevel in enamel. After pretests with modification spaces of 11 and 17 mm (length), 2 missing premolars were replaced by the ceromer Targis and reinforced with the glass-fiber material Vectris. The prostheses were inserted with Tetric Ceram with use of an ultrasonic-supported, high-viscosity technique. Restorations were selectively bonded to cavity finish lines in groups 1 and 2 ("selective bonding"). In group 3, restorations were bonded totally to the whole cavity surface ("total bonding"). The restorations were stressed in a computer-controlled masticator. Marginal quality was examined with an SEM at ×200. Results. The percent area of optimal margins after thermomechanical loading between composite and enamel in each group was as follows: group 1, 86.2% ± 12.3% for canines and 95.5% ± 3.5% for molars; group 2, 95.3% ± 2.1% for canines and 96.2% ± 2.7% for molars; and group 3, 95% ± 0.9% for canines and 86.4% ± 3.2% for molars. The marginal quality for molars inserted with total bonding was significantly lower ( P ≤.05). Conclusion. Within the limitations of this study, the selective bonding technique for slot inlay-retained fixed partial dentures resulted in a negligible loss of marginal quality after extensive mechanical and thermal stress. The selective bonding technique is recommended for box-shaped cavity preparations. (J Prosthet Dent 2001;86:81-92.)

Ectodermal dysplasia, in all its varieties, occurs in approximately 1 in every 100 000 live births. Depending on the variety, hypohidrosis, hypotrichosis, hypodontia, oligodontia, and/or anodontia may be exhibited. Few long-term clinical reports exist. This report follows the development, growth, and initial treatment of a 10-year-old patient with ectodermal dysplasia and his subsequent oral rehabilitation 20 years later.

Statement of problem. Special technical skills and experiences are required to fabricate a telescopic crown to provide adequate retention with precise frictional retention ("conus friction force") between coping and telescope. It is also difficult to control clinically alterations of retentive forces after prolonged usage. Purpose. This study examined an innovative telescopic crown system for removable partial dentures that can be fabricated without special technical skill or experience and readily adjusted retentive forces. The retention of telescopic crowns was investigated after repeated insertion/separation tests. Material and methods. Ten telescopic crowns were constructed to evaluate retentive forces. Each telescopic crown was adjusted to provide a retentive force of approximately 9.8 N. Each telescopic crown was then subjected to 10,000 insertion/separation cycles, and retentive force of each telescopic crown was recorded initially and after every 1,000 cycles. The retentive force of each telescopic crown was re-adjusted after these measurements to provide a retentive force of approximately 9.8 N. The retentive force was recorded a second time after each 1,000 insertion/separation cycles up to 10,000 cycles. Results. Retention of the telescopic crowns gradually diminished, depending on the number of insertion/separation cycles. The mean retentive force after 10,000 insertion/separation cycles was over 2 N. All 10 telescopic crowns were re-adjusted to exert a retentive force of 9.8 N after the initial 10,000 cycles, and the retentive force also diminished on the second 10,000 cycles. Conclusions. Reduction of retention was dependent on insertion/separation cycles. This new telescopic crown with reduced retention could be easily readjusted. Readjusted retentive forces were at least equivalent to the initial retention. (J Prosthet Dent 1999;81:684-8.)

When a tooth prepared for a crown does not comply with the general principles of retention and resistance form, and it is not possible to correct it without damage to the biologic structures of the tooth, consideration must be given to the purpose of the crown, such as whether it is a single crown, a retainer for a fixed restoration, or a retainer for a fixed removable prosthesis with precision attachments. The crown prepared with receptacles for internal attachments will undoubtedly require more retention and resistance to dislodgment than a single crown because of forces that will be applied to it through the removable portion of the restoration. The purpose of this article is to present an alternative procedure that uses the intracrown ring, which provides additional retention for the abutment crown because of the compressible ring. The compressible ring is placed in the groove prepared in the lower third of the abutment during the crown preparation. (J Prosthet Dent 1999;81:218-23.)

Statement of problem. It is unknown what minimum number of implants are required to satisfactorily support and retain a mandibular overdenture. Purpose. The purpose of this study was to evaluate a treatment modality by using mandibular overdentures anchored to single implants in a geriatric patient population. Material and methods. Twenty-one patients with a mean age of 74.2 years were treated with single implants inserted at the mandibular midline according to the standard two-stage surgical technique. O-Ring or ball attachments were connected to the implants and served as overdenture anchorage. Implant success rate, improvement of oral comfort and function, condition of the peri-implant soft tissues, Periotest values, and the interproximal marginal bone level were evaluated for up to 5 years after delivery of the overdentures. Results. None of the implants were lost during the follow-up period. A mean marginal bone loss of 1.42 ± 0.56 mm was noted at 60 months. Plaque Index was consistently high around the abutments at all reevaluation intervals but was associated with a low Gingival Index. Pocket Depth averaged 2.41 ± 0.17 mm for the entire follow-up period. Remarkable improvement of oral comfort and function were evidenced with the overdenture treatment. Conclusion. Rehabilitation with mandibular overdentures anchored to a single implant can be a therapeutic alternative for elderly patients experiencing discomfort and functional difficulties with conventional mandibular dentures. (J Prosthet Dent 1997;78:159-65.)

A technique is described that allows a removable partial denture with a broken clasp or a removable partial denture in which an abutment has been extracted to be restored by the reattachment of a new cast clasp component or a complete surveyed clasp assembly. The technique is applicable to most clasp designs and can include attachment to the acrylic denture base or the metal major connector. The technique is distinguished from other repair techniques by (1) providing a cast clasp replacement, (2) allowing the patient to retain the prosthesis during the repair, (3) generating a precisely formed surveyed clasp assembly by the laboratory, and (4) including an efficient transfer mechanism for the precision clasp created in the laboratory to be attached to the removable partial denture in the dental office. A two-step impression procedure is used to ensure proper relation of the partial denture to the abutments.

The preservation of teeth to support an attachment-retained overdenture is an appropriate and stable alternative to extractions and complete dentures. A key to success is the strategic selection of teeth for retention. This clinical report discusses a method for fabricating an overdenture based on a combination of direct and indirect impression techniques. This technique is a simple and time-efficient alternative to traditional methods that aids in overcoming difficulties in fabricating overdentures.

In this study two precision overdenture attachment designs were tested for retention—a nylon overdenture cap system and a new cap and keeper system. The new cap and keeper system was designed to reduce the time involved in replacing a cap worn by the conditions of the oral environment. Six groups were tested at two different angles and retentive failure was examined at two different angles (26 and 0 degrees). Failure was measured in pounds with a force gauge over a 2000 pull cycle. The amount of force required to remove caps for two overdenture caps and a replaced cap for the metal keeper system was determined. Two dependent variables were absolute force and relative force. Repeated measures analysis of variance (RMANOVA) was used to compare the between-subjects effects of cap and angle, and the within-subjects effect of pull. The results indicated a significant difference between cap types (p < 0.0001) with respect to the relative force required to remove the cap. There was no effect of angle. For absolute force, RMANOVA revealed a highly significant interaction between pull and cap (p < 0.0001). Thus, the way that force changed over pulls depended on which cap was used (no effect of angle). For relative force, RMANOVA revealed no interaction between pull and cap, but there was a main effect of cap type (p < 0.0001) (no effect of angle). The nylon cap design required less force for removal but showed more consistency in the force required over the course of the 2000 pulls when compared with the keeper with cap insert. The results obtained in this study were consistent with similar studies in literature.

Although implant-retained overdentures are a less expensive alternative to fixed implant-supported prostheses in certain situations, problems with retentive clips fracturing and needing frequent replacement have been reported. This study compared baseline and posttest retention of metal and plastic clip-retained overdenture analogs and monitored surface changes in bars and clips throughout the testing process. A laboratory model was made with two implant analogs processed into an acrylic resin platform to which three bars were fitted. Two overdenture analogs were made and retained on the model with metal or plastic clips. Each bar-clip assembly was subjected to 5500 insertion and removal cycles to simulate 3 years of in vivo insertion and removal. Although the differences in retention between metal and plastic clips and between clips before and after testing were statistically significant, it is questionalbel whether they are clinically significant. Neither clip fracture nor loss occurred during this study, which suggests that it may be functional or parafunctional loading and not repeated insertion and removal of an implant overdenture that may cause the stated problems.

Seventeen subjects with preexisting conventional complete dentures were evaluated in this prospective clinical study. Two implants were placed bilaterally in the anterior mandible. In a crossover experimental design, the conventional dentures were modified, and the retention, stability, and tissue response for conventional dentures were compared with implant overdentures that had O-ring and magnet overdenture attachments for all subjects. The study indicated statistical superiority of the implant overdenture to the conventional denture. The O-ring attachment proved significantly better than the magnet attachment for retention and stability. The soft tissue response showed a slight but significant improvement with implant overdenture therapy.

Inlay fixed partial dentures luted by use of adhesive procedures offer a clinical alternative for the restoration of single missing posterior teeth. The introduction of ceromers and fiber-reinforced composites and the continuous improvement of adhesive systems and luting agents make this type of restoration possible, offering good aesthetic and functional results. The procedure is minimally invasive and conservative. This clinical report reviews the factors influencing the diagnosis and the clinical indications for an inlay fixed partial denture. In addition, a patient treatment is presented to illustrate the clinical procedures involved.

A variety of techniques have been reported in the literature for the incorporation of attachments in implant-retained partial and complete overdentures with unsplinted or individual abutments. Three important elements that are necessary in describing any technique for incorporation of attachments are the type of final impression method (tissue-level impression, abutment-level impression, or implant-level impression), stage of overdenture fabrication (record base stage, denture-processing stage, or denture insertion stage) and nature of technique (direct or indirect). This article reviews 7 different techniques for the incorporation of attachments in implant-retained complete and partial overdentures. Discussion of indications, contraindications, advantages, and disadvantages of each technique is provided to aid the clinician in making an appropriate choice.

Resilient (nonrigid) and non-resilient (rigid) attachments are used in extension base partial removable dental prostheses for retention. However, the biomechanical effects of these 2 types of retainers on the terminal abutment and supporting tissues, which may influence clinical treatment planning, have not been compared.The purpose of this study was to compare the mechanical effects of 2 types of extracoronal attachments (rigid and nonrigid) in distal extension removable partial prostheses on the alveolar ridge and abutment tooth periodontal ligament.A finite element model of a human left mandible edentulous arch distal to the second premolar was fabricated. The second premolar was the terminal abutment for an attachment-retained denture. Two types of attachments (rigid and nonrigid) were modeled in the study. For the nonrigid attachment, there was movement between the patrix and matrix component of the attachment, but there was no movement between the 2 component parts for the rigid attachment. Six levels of loading (100, 150, 200, 250, 300, and 350 N) were applied from 3 directions (axial, buccolingual, and mesiodistal) on the central fossa of the first and second molars. Denture motion and stress distributions of denture supporting tissues were observed. Maximum equivalent stress values (SEQV) were recorded for 6 regions (cervical bone, cervical and apical periodontal ligaments, mesial and distal ridges, and mucosa). The data were divided into 2 groups according to the attachment type. Paired t tests were used to compare the values of the 2 groups. Factorial ANOVA was used to test the difference between the loading directions (α=.05). Multiple linear regression was used to analyze the interactions among the factors of region, direction, and level (α=.05).Stress distributions in the rigid and nonrigid attachment models were similar but the magnitudes were different. For all 3 loading directions, significantly different stresses in the alveolar ridge and periodontal tissue of the terminal abutment were found between the rigid and nonrigid groups (P.05). There were significant differences among the 3 loading directions (P.05). In the nonrigid group, the stress ratio of the mesial to the distal area was higher than that of the rigid group from axial and mesiodistal loading (P.05). Linear interactions were found between the direction and level and region and level combinations (P.05). Movement between the patrix and matrix components increased as loading increased. The most obvious movement of attachment occurred when loading was in the buccolingual direction.Stress on the terminal abutment can be reduced by the use of an extracoronal resilient attachment that allocates more loads onto the distal edentulous ridge. The level of loading influenced the extent of reduction. A resilient attachment with a universal hinge had the most movement when loading was in the buccolingual direction. Interactions were found between direction and level, as well as region and level combinations (P.05).

Statement of problem Magnetic attachments are commonly used for overdentures. However, it can be difficult to identify and provide the same type and size of magnetic assembly and keeper if a repair becomes necessary. Therefore, the size and type may not match. Purpose This study evaluated the retentive force and magnetic flux strength and leakage of magnetic attachments in different combinations of keepers and magnetic assemblies. Material and methods For 6 magnet-keeper combinations using 4 sizes of magnets (GIGAUSS D400, D600, D800, and D1000) (n=5), retentive force was measured 5 times at a crosshead speed of 5 mm/min in a universal testing machine. Magnetic flux strength was measured using a Hall Effect Gaussmeter. Data were statistically analyzed using a 1-way ANOVA, and between-group differences were analyzed with Tukey's HSD post hoc test (α=.05). Results The mean retentive force of the same-size magnet-keeper combinations was 3.2 N for GIGAUSS D400 and 5.1 N for GIGAUSS D600, but was significantly reduced when using larger magnets ( P Conclusions Size differences influence the retentive force and magnetic flux strength of magnetic attachments. Retentive force decreased due to the closed field structure becoming incomplete and due to magnetic field leakage. (J Prosthet Dent 2011;105:266-271)

An in vitro study that used photoelastic models compared stress distribution characteristics of three maxillary, bilateral, distal-extension removable partial denture designs when the abutments were subjected to a progressive loss of periodontal support. One design used I-bar retention, a second design used a semiprecision, spring-loaded plunger attachment, and a third design used the ERA attachment. Both attachment designs were tested with and without splinted abutments. The ERA design was also tested with and without supporting rests and included light and heavy retention elements. Periodontal support loss up to 35%, a 60/40 crown-to-root ratio, resulted in increased stress concentrations. The ERA design with supporting rests, light retention elements, and splinted abutments compared very favorably with the I-bar retained design on nonsplinted abutments.

The technique described uses innovative technology and conventional prosthodontic techniques to directly assemble a cast framework to implant abutments with a resin luting agent. This technique has been used to restore multiple implants with a fixed restoration and for implant connecting bars to support overdentures. Brånemark and Calcitek implant systems have been used successfully.

The author suggests a special design for a tissue-supported, distal extension removable partial denture for patients who require a combined fixed-removable prosthesis.

This study determined the retention, in pounds, of Nos. 1 through 3 stainless steel attachment sleeves for the threaded split post system cemented with various cements. Post heads and matching sleeves were also sandblasted and compared with attachments not sandblasted. Four luting agents were selected, zinc oxyphosphate cement (ZOP), and three brands of composite resin cement (CRC). The experiment was divided into two parts; in part 1, samples were not treated, and in part 2, samples were sandblasted. Retentive values were recorded with a universal testing machine. A 2 × 3 × 4 factorial three-way analysis of variance was used to compute the effects sandblasting, sleeve and post type, and the luting agent. No statistical differences were recorded for sleeves not sandblasted, Nos. 1 and 2, regardless of the luting agent. The nonsandblasted No. 3 sleeve cemented with Panavia CRC had significantly greater retention than All-Bond CRC or ZOP. There were no statistical differences in retention of sandblasted sleeves for the No. 1 sleeve despite the type of luting agent. For sandblasted sleeves Nos. 2 and 3, ZOP and Panavia CRC recorded significantly greater retention than All-Bond CRC. However, there was no difference between sandblasting and not sandblasting for the No. 1 sleeve. Mean loads for Nos. 2 and 3 sleeves were substantially greater for sandblasted compared with attachments not sandblasted.

This study photoelastically compared the stress distribution characteristics of maxillary, bilateral, distal-extension removable partial dentures retained by light and heavy ERA extracoronal attachments. One prosthesis included supporting rests and the other had no rests. Both designs were tested with and without abutment splinting. The most favorable stress distributions were obtained with light retention elements, supporting rests, and splinting of the abutments. In this configuration the attachment prosthesis compared favorably in stress distribution with the maxillary I-bar retained removable partial denture in a previous study that used a comparable maxillae model.

The principles of the laboratory procedures for making overdentures retained by bar abutments on ITI implant fixtures are described, and details of producing the master casts, making a soldered bar, and processing a prosthesis incorporating a cobalt-chromium alloy strengthener are given.

Limited space over abutment teeth may make incorporation of a precision attachment system within an existing overdenture technique sensitive. A special diagnostic index can be made to depict the available space within the prosthesis over the abutment teeth. This index is critical to determine the feasibility of attachment incorporation, as well as the selection and correct positioning of an appropriate attachment system. A method to improve predictability for precision attachment incorporation into an existing overdenture is described.

A technique is described for constructing the implant-retained overdenture with heat-polymerized silicone that is processed around undercuts in a round bar framework connecting the implants. An acrylic resin circular rest contacting the bar ensures that the implants are loaded in occlusion for stress distribution over the fixtures.

The dentition of partially edentulous patients with an anterior modification space may be restored in several ways. If a removable partial denture is selected as the treatment of choice, denture tooth selection, direct retainer display, and anteriorposterior rotation may be sources of concern for the patient and dentist. A way to overcome the treatment problems associated with these partially edentulous patients is use of a Hader bar and clip-retained removable partial denture with the attachment of an anterior porcelain-fused-to-metal facade. This article describes this treatment option and the technique for fabrication.

The development of dental implants has led to an expansion of indications and to perfection of implantation methods and implant systems. Angulation problems due to anatomic limitations, however, still remain. The indications for the use of angled Bonefit I.T.I. implants are described.

A precise fit at the prosthesis attachment interface is necessary to assure atraumatic loading of the implant fixture. The required high degree of frame accuracy can be more difficult to achieve when a single fixed prosthesis uses different root form implant systems for support. Two clinical protocols are described for these fixed implant prostheses. The first protocol uses a semiprecision attachment for the restorations. The second protocol uses a modified abutment system and a one-piece frame design.

STATEMENT OF PROBLEM The retentive capacity of ball attachments may be altered by a change in implant angulations. PURPOSE The purpose of this in vitro study was to investigate the effect of cyclic dislodgement on the retention of an overdenture attachment system when 2 implants were placed at angulations of 0, 5, 10, 15, and 20 degrees. MATERIAL AND METHODS Twelve acrylic resin blocks were fabricated and divided into 6 groups of 2 pairs each. In each of the 6 groups, 1 acrylic resin block was used to house the implants (block A), while the other (block B) was used to house the overdenture attachments. Two implants positioned at 0/0 degrees, with a standard plastic component(white) designed for 0-degree angulations, served as a control (CTRL), while the other 5 pairs of implants were placed in 5 different angulations: 0D: 0/0 degrees, 5D: 5/5 degrees, 10D: 10/10 degrees, 15D: 15/15 degrees, 20D: 20/20degrees (n=5). The extended range (green color) attachment was used for all groups except the control group. Implants(4.3 mm x 13 mm, internally hexed) were placed in blocks B. All angled implants were mesially tilted. Thirty pairs of attachments (Locator) were used. Dislodging cycles were applied to the overdenture attachment system. The initial retentive forces among the groups were not identical. The cycles required for the retentive forces of the attachments to decrease from the initial values to 60 N, and then to 40 N and 20 N, were recorded for standardization purposes.One-way ANOVA and Tukey HSD tests were used to analyze the difference in retention loss among the 6 groups(alpha=.05). A regression analysis (alpha=.05) was also performed to investigate the relationship between the implant angulation,the retentive force, and the logarithm of the number of cycles required for ball attachment retention decrease. RESULTS The 1-way ANOVA and the Tukey HSD tests revealed significant differences for the number of cycles required by different implant angulation groups for the initial retentive values to decrease to 60 N, 40 N, and 20 N (P

Statement of problem Nonparallel implants, when used to retain overdentures, may present a restorative challenge, particularly when using attachments. Premature wear of the components and loss of retention may be observed, resulting in increased maintenance. Purpose The purpose of this study was to compare the retentive behavior, over time, of spherical attachments when used in nonparallel and parallel implant scenarios in a cyclic testing mode. Material and methods Thirty sets of 2-implant-supported overdenture models were evaluated: 4.0 × 13-mm implants (Astra-Tech Osseospeed) with 1.5-mm ball abutments (Astra-Tech) were used as the intraoral analog to the implants, and spherical attachments (Preci Clix) were used as the overdenture analog. Five different attachment and implant-abutment complex angulations were evaluated. Angulation was determined by deviation from the vertical reference plane. The groups consisted of the following: Group 0-0, 0-degree implants/0-degree attachments; Group 10-0, 10-degree implants/0-degree attachments; Group 15-0, 15-degree implants/0-degree attachments; Group 10-10, 10-degree implants/10-degree attachments; and Group 15-15, 15-degree implants/15-degree attachments. The specimens were subjected to cyclic loading (3500 cycles). Peak and valley retention loads were recorded at the first pull and then after every 100 cycles; therefore, 36 data points per specimen were recorded. Nonparametric analyses followed by post hoc analyses were conducted to test for differences in median peak load among groups (α=.05). Results Peak load to dislodgment values for all groups ranged from 11.43 N to 23.56 N. Group 0-0 had the highest median retention value overall, 21.3 N, and Group 15-15 had the lowest median value, 17.3 N. Nonparametric analyses showed significant differences between Groups 0-0 and 15-15 ( P =.014); and 10-0 and 15-15 ( P =.002). Conclusions Within the limitations of this study, it was observed that there was a decrease in retention in the groups with 30-degree divergent implants and divergent attachments compared to the groups with parallel implants and parallel attachments. In general, retention varied from 11 N to 23 N, and attachment retention stabilized after initial loss in most groups. (J Prosthet Dent 2009;101:231-238)

Despite recent developments in dental implantology, 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.

A method for making an improved index for the waxed stage of Branemark implant-retained frameworks is described. The index improves visibility of the tooth and abutment cylinder relationship permitting the optimization of framework dimensions and contour.

aAssociate Professor, Department of Restorative Dentistry, School of Dentistry, Loma Linda University. bAssociate Professor, Department of Restorative Dentistry, School of Dentistry, Loma Linda University. cProfessor, Director, Division of Postdoctoral Prosthodontics, Department of Restorative Sciences and Biomaterials, Goldman School of Dental Medicine, Boston University. (J Prosthet Dent 2008;100:406-407) Two of the most common implant complications with the use of attachments are overdenture clip/ attachment loosening (30%) and overdenture clip/attachment fracture (17%).1 These problems are related to the nature of the nylon or plastic clips available for use with implant-retained overdentures. A metal attachment that engages the implant bar (SwissLoc NG; Attachments Intl, Inc, San Mateo, Calif ) (Fig. 1) can also be used in addition to the clips. The use of a locking, plunger-type metal attachment prolongs the useful life of plastic clips. These plunger attachments are commonly placed on the buccal surface of the overdenture flange with a mesial depression in the surrounding acrylic resin to facilitate removal by the patient’s fingernail. This buccal placement is convenient and practical, and will not interfere with esthetics when placed in a mandibular denture. However, when these attachments are placed in a maxillary denture, esthetic concerns and flange thickness commonly prevent their placement on the facial surface of the denture flange, and they are usually placed on the palatal surface of the implant-supported overdenture. Because of the depression in the acrylic resin, the plunger head may be annoying to the patient’s tongue and can cause tongue soreness (Fig. 2). When the plunger head is at the same level as the surrounding acrylic resin, access to unlock the attachment is not feasible. The purpose of the article is to describe a method of making a device to disengage a palatally placed plunger-type attachment (Fig. 3). PROCEDURE

This clinical report describes the prosthodontic rehabilitation of a patient with a partially edentulous maxilla and compromised mandibular anatomy caused by resection of bone due to basal cell carcinoma. Placement of a fibula bone graft was followed by placement of 2 implants. The implants were malpositioned in the anteroposterior plane due to the altered form of the alveolar bone. Prosthodontic treatment included a maxillary removable partial denture and a mandibular partial overdenture supported by implants and remaining teeth. (J Prosthet Dent 2008;99:174–177)

This article describes a procedure that uses the Ney MS (Minimal Space) intracoronal attachment as an interlock in a pontic. This procedure overcomes the disadvantages associated with the use of the intracoronal attachments, which are (1) excessive tooth reduction often required to place the attachment within the contour of the crown; (2) compromised embrasures, which result in oral hygiene and periodontal problems; and (3) poor esthetics. (J Prosthet Dent 1998;79:347-9.)

Ball-type attachments are commonly used for implant-retained overdentures. The matrix is designed to be rotational to the path of insertion of the denture, especially for situations with multiple implants (Fig. 1). Securing the matrices during the transfer procedure, therefore, is important. Stabilizing devices (Directional ring; BioHorizons Implant Systems, Inc, Birmingham, Ala) are available; however, the devices have only 3 different degrees of inclination and may not be able to orient the matrices to allow for optimal parallelism. The attachments or the abutment undercutsmust be blocked out before connecting the matrices to the denture. The use of rubber dam material has been proposed in the literature, but this material cannot stabilize the matrices during the transfer procedure. Keys suggested using the orthodontic rubber spacer to secure the matrices, but the draw of the matrices must follow the axis of the implant. The material used for the blockout of the ball-type attachments must be stiff and easily contoured and removed. This article presents a technique using lightpolymerized composite resin to stabilize the matrices and block out the undercut during the transfer procedure.

Implant-supported overdentures retained by attachments are now an established treatment method. The mandible is well suited for implant-retained overdentures, particularly when the implants can be placed in the canine regions. Among available retention systems, ball attachments have been proven to be reliable. The ball attachment consists of a spherical patrix that is usually screwed into the implant assembly. The matrix fits over the patrix and provides retention by means of spring-action arms or an interchangeable elastic ring. The connection between the matrix and the denture can be achieved by indirect or direct method. The indirect technique consists of recording the denture’s soft tissue support as well as positioning the implants in relation to the denture, so that the connection of the matrix and the reline procedure can be completed in the laboratory. This method has the potential advantages of reduced chair time and the use of a single denture base acrylic resin. However, the recording and transferring of the implants position with analogs may introduce some misfit. Moreover, the patient is without the prosthesis during this time. The direct technique for locating a ball attachment intraorally is simple, economic, quick, and allows the patient to retain the prosthesis. If relining of the prosthesis is indicated, the reline should be completed as a preliminary step. Few connection procedures have been proposed in the literature. This article describes a clinical procedure for a direct connection between a complete mandibular overdenture and 2 supra-implant nonsplinted attachments, using a rubber dam to prevent the acrylic resin from entering into the undercut areas located under the head of the implant or under the patrix portion of the attachment. This method prevents compression of the gingival peri-implant soft tissue, and allows the denture to be seated completely on the supporting surface.

This clinical report describes a multidisciplinary approach for the treatment of a patient with Angle Class III skeletal malocclusion and decreased occlusal vertical dimension. An overlay removable partial denture (ORPD) was used to reestablish the occlusal vertical dimension (OVD). After the trial and adjustment period, the reduced lower anterior dentofacial height was orthodontically increased and the negative horizontal overlap was corrected. A maxillary precision attachment RPD and a mandibular fixed partial denture and metal ceramic crowns were fabricated to satisfy esthetic and functional requirements.

Dental implants or precision attachments can be used to resolve the bilateral distal extension removable partial denture (RPD) dilemma. This report describes the fabrication of a mandibular implant-supported chromium-cobalt RPD with a combination of bilateral single molar implants and metal ceramic crowns using the principles of the channel-shoulder-pin system. The maxillary arch was restored with splinted metal crowns and a conventional RPD retained by extracoronal precision attachments.