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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.

Background A shortened dental arch (SDA) is an established treatment concept for patients with missing molars. However, little is known regarding long-term course of oral health-related quality of life (OHRQoL) in patients with SDA and the benefits from replacement of missing molars. Aim Purpose of this multi-center randomized clinical trial was to assess OHRQoL over a period of 15 years in patients with molar replacement by a removable partial denture (RPD) compared to patients with a restored SDA without molar replacement. Design Patients at least 35 years of age with all molars missing in one jaw and at least the canine and one premolar present on each side were included. Patients received either a precision attachment-retained, RPD for replacement of missing molars (N=79), or the dental arch ended with the second premolar (SDA) that had to be present or replaced by a cantilever fixed dental prosthesis (N=71). Follow-up examinations continued for 15 years. OHRQoL was assessed with the 49-item Oral Health Impact Profile (OHIP). OHIP summary and dimension scores were longitudinally modeled in the statistical analyses to assess course of OHRQoL over time applying an intention-to-treat approach. In addition, scores for the OHRQoL dimensions Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact were analyzed. Results After an initial improvement in OHRQoL indicated by a mean decrease of 20.0 OHIP points with an effect size of 0.61 in the entire study population, OHRQoL stayed relatively constant over the entire follow-up period. Assuming a constant time and treatment effects over the study period, OHRQoL did not differ statistically significant between the two treatments (0.4 OHIP points; 95%-CI: −7.1 to 6.2). OHRQoL after treatment did not change notably over 15 years and was statistically nonsignificant as well (p=0.872). Similar findings were observed in all four OHRQoL dimensions. Conclusions In patients, missing all molars in one jaw OHRQoL improved providing RPD or restoring SDA to a clinically relevant degree. Treatment-related improvement remained mostly stable over a period of at least 15 years. Therefore, patients can be informed that both treatment concepts are equivalent concerning long-term OHRQoL. Accordingly, patients’ preferences regarding treatment options should be granted priority in treatment decision making with the SDA treatment option being the default.

Splinted and unsplinted overdenture attachment systems have unique advantages and disadvantages. The aim of the present systematic review was to determine the influence of splinted and unsplinted overdenture attachment systems on the marginal bone loss, prosthetic complications and implant survival rate. PubMed/MEDLINE, Scopus and Cochrane databases were searched for articles published up to October 2017, using the following search terms: "overdenture AND attachment OR overdenture AND bar OR overdenture splinted." The PICO question "Do splinted overdenture attachment systems promote better clinical results in comparison to unsplinted systems?" was evaluated. Eligible studies included randomized controlled clinical trials, prospective studies with at least 10 participants and a minimum follow-up of 6 months, and studies published in English that compared splinted and unsplinted attachment systems within the same study. The 95% confidence interval (CI) was considered for all outcomes analysed. After completion of the different steps in the article selection process, nine articles were included in the qualitative and quantitative analyses. A total of 984 implants were placed in 380 patients (mean age: 62.8 years). The meta-analysis demonstrated no statistically significant differences between splinted and unsplinted attachment systems with regard to marginal bone loss (P = .39; MD: -0.11; 95% CI: -0.37 to 0.14), complications (P = .31; RR: 1.26; CI: 0.80-1.99) and implant survival rate (P = .14; RR: 0.37% CI: 0.10-1.36). In addition, splinted and unsplinted overdenture attachment systems achieved similar results with regard to marginal bone loss, prosthetic complications and implant survival rate.

Implant-supported overdentures are an established dental treatment mode. The aim of this prospective study was and interindividual comparison of patient satisfaction with restorations retained by a prefabricated and thus inexpensive attachment system (Locator®) or with a technologically complex and thus expensive attachment system (ceramic/electroplated double crowns) with similar retentive performance. Twelve patients received a Locator and a double-crown prosthesis in a crossover study for test periods of 3 months each. The main target parameter was the patient’s final decision in favor of one of the two prosthesis types. After completing both test phases, seven patients opted for the Locator prosthesis and five patients opted for the double-crown prosthesis. Given the predominant lack of statistically significant differences, the two types of prostheses can be described as equivalent. A recommendation in favor of the Locator prosthesis can be motivated by its lower cost. The results of the study show that the more cost-effective variant was comparable to the more expensive double-crown prosthesis under the conditions prevailing in the study. Depending on the indication, this may influence the decision-making process in daily clinical practice and support the clinician’s patient information and consultation efforts.

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.

PURPOSE The purpose of this preliminary study was to examine the influence of overdenture attachment height and shape on lateral force on implants and denture displacement. MATERIALS AND METHODS A straight model was fabricated to simulate the edentulous ridge. Two strain gauges were attached to the mesial and distal surfaces of the implant in the canine area. Five types of ball attachments and three types of Locator attachments with three types of replacement male attachments were used. A vertical load of 49 N was applied. The lateral force on the implant and the denture displacement were measured. Statistical comparisons were performed using one-way analysis of variance, Tukey post hoc comparison test, and multivariate analysis. P < .05 was considered significant. RESULTS Ball attachments of 4-mm height exerted the highest lateral force on the implant, and the greatest displacement was also observed with attachments of 4-mm height. Different lateral forces were observed for different shapes of ball attachments, but there were no significant differences in denture displacement among the shapes. For Locator attachments, the highest lateral force was observed with the white male type, and the greatest denture displacement occurred with attachments of 4-mm height. There were no significant differences among male white, pink, and blue types. CONCLUSION The height of the stud attachments in implant overdentures had a marked effect on the lateral force on implants and on denture displacement. To protect implants supporting an overdenture and to prevent bone resorption, the height of the attachment should be carefully considered.

Purpose The stress-breaking ball (SBB) attachment can distribute the occlusal force equally between the alveolar ridge and the implants. The purpose of this study was to evaluate the implant-supported distal extension removable partial dentures (RPDs) with SBB attachment in 10 patients who were partially edentulous. Methods This randomized crossover study was designed to compare the function of RPDs with and without healing abutments and SBB attachments to support the posterior aspects of the RPDs. Mandibular jaw movements during mastication and the occlusal force and contact area were measured with a commercially available tracking device and pressure-sensitive sheets. Using a visual analog scale, 4 criteria-chewing, retention, stability, and comfort-were evaluated. All of the data obtained were analyzed using a 1-way analysis of variance (α = 0.05). Results There were no significant differences in either the mean time or the coefficient of variation among the SBB attachments and healing abutments of implant-supported removable partial dentures (ISRPDs) and conventional removable partial dentures (CRPDs). SBB attachments and healing abutments of ISRPDs had greater forces and contact areas than those of CRPDs with significant differences. For all criteria, patients preferred SBB attachments to healing abutments and CRPDs. Conclusions The implant-supported distal extension RPDs with SBB attachment improved denture stability and patients' satisfaction.

The purpose of this study was to evaluate the change in the retentive forces of four different titanium-based implant attachment systems during the simulation of insert&ndash, removal cycles in an artificial oral environment. Five types of titanium-based dental implant attachment systems (Locator, Kerator, O-ring, EZ-Lock, and Magnetic) were studied (n = 10). The specimens underwent insert&ndash, removal cycles in artificial saliva, and the retentive force was measured following 0, 750, 1500, and 2250 cycles. Significant retention loss was observed in all attachment systems, except the magnetic attachments, upon completion of 2250 insertion and removal cycles, compared to the initial retentive force (p &lt, 0.05). A comparison of the initial retentive forces revealed the highest value for Locator, followed by the Kerator, O-ring, EZ-Lock, and Magnetic attachments. Furthermore, Kerator demonstrated the highest retentive loss, followed by Locator, O-ring, EZ-Lock, and Magnetic attachments after 2250 cycles (p &lt, 0.05). In addition, the Locator and Kerator systems revealed significant decrease in retentive forces at all measurement points (p &lt, 0.05). The retention force according to the insert&ndash, removal cycles were significantly different according to the types of dental implant attachment systems.

The aim of this study was to compare and evaluate the retention of two new attachment systems used for implant-supported overdentures subjected to insertion-removal cycles.Twenty custom-manufactured polyvinyl chloride models mimicking implant-retained over-dentureresin blocks were fabricated and divided into two groups (n = 10): group 1 ('Kerator' attachment) and group 2 ('EMI' attachment). Each model received two parallel implants (JD evolution®) 20 mm apart and was subjected to cyclic retention forces of 10, 100, 1000, 5000, 10000 and 14600 cycles using a universal testing machine in a 0.9% sodium chloride water solution at 22° C. Data were analyzed using one-way analysis of variance; the level of significance was set at a0.05.The 'Kerator' and 'EMI' attachment systems reported a significant decrease in retention (64 and 56.6% respectively) after 14600 insertion-removal cycles (p0.001). The 'EMI' attachment showed significant higher loss of retention than the 'Kerator' attachment all along the 14600 cycles (p0.05) except for cycles 100 and 5000 (p0.05).Within the limitations of this in vitro study, both attachments reported satisfactory retentive values during the 14600 cycles, the 'Kerator' attachment showed better retention than the new 'EMI' attachment. The initial retentive force of both attachments has gradually decreased.Both attachment systems evaluated in this study can be used in clinical practice for implant-supported overdentures.

Purpose: The aim of this study was to evaluate the effect of a computer-aided design/ computer-assisted manufacturing (CAD/CAM) guide on drilling the screw-access channel for lingually placed implants. Materials and Methods: Screw-channel drilling guides were fabricated on lingually placed implant models using CAD/CAM technology. The screw channels were prepared with guided or freehand drilling by 20 dental graduates. The accuracy of each screw channel was assessed for drilling entry point, channel volume, and angulation (α = .05). Results: The guided drilling group showed smaller deviations than the freehand drilling group, and prosthesis position influenced the guide effect (P < .001). Conclusion: The CAD/CAM guide facilitated the screw channel preparation of cement-retained prostheses supported by lingually placed implants.

In this study, we investigated the retention of two attachment types, Straumann ball (SB) and Straumann LocatorThe attachments placed on angulation of 0°-, 10°-, and 20° implants were subjected to 1440 vertical insertion-separation cycles. The retention values of the attachments after 0, 720, and 1440 cycles were measured using the Instron machine. In addition, scanning electron microscopy images of the attachments and abutments were obtained before and after the insertion-separation process.There was a significant difference between the SB and SL attachments that were placed on 0° after 1440 cycles (P0.05) and between 20° SB and 20° SL attachments after 720 and 1440 cycles (P0.05) in terms of retention. No significant difference was observed between 20° SB and 20° SL attachments at 0 cycles (P0.05).In implants with a 20° angle, retention of stud attachments decreased more than ball attachments after use. Thus, the total angle between the implants should not be20° if long-term retention is desired when using stud attachments. For implants with angles20°, 6-month patient controls are required to control retention of attachments by considering factors in the mouth with the two tested attachment systems.

Purpose This study aimed to compare the long-term outcomes of two different nonimplant treatments in the bilateral shortened dental arch (SDA). Materials and methods In a multicenter randomized controlled clinical trial, patients with complete molar loss in one arch were assigned to one of two different nonimplant treatments. In the partial removable dental prosthesis (PRDP) group, patients were provided with a distal-extension prosthesis retained with precision attachments. In the SDA group, patients were treated according to the SDA concept by preserving or restoring a premolar occlusion. Results Of the 152 treated patients, 82 reached the 10-year examination independent of their dental or prosthetic status. In the intention-to-treat analysis, the survival rates for tooth loss at 10 years were 0.44 (95% confidence interval [CI]: 0.30 to 0.56) in the PRDP group and 0.52 (95% CI: 0.37 to 0.65) in the SDA group. For tooth loss in the study arch, the survival rates were 0.67 (95% CI: 0.52 to 0.78) in the PRDP group and 0.60 (95% CI: 0.45 to 0.73) in the SDA group. The number of teeth lost was higher than expected. In a multivariate analysis using a multiple Cox regression model, the covariates age (unit: 1 year, Hazard Ratio [HR]: 1.033, P = .03) and DMFT value (unit: 1 tooth, HR: 1.121, P = .03) were significant for time to first tooth loss in the study arch. Conclusion The results suggest an overestimation of the influence of the prosthetic management of the bilateral SDA. In treatment decisions, patient preferences should be considered with appropriate weight.

U ovom kliničkom prikazu opisan je, kod parodontno ugroženog pacijenta s nekontroliranim dijabetesom, fiksni maksilarni most od estetskoga kompozitnog materijala s metalnom bazom učvršćen na frezanim metalnim kapicama. Uključena su i mjesta za okluzalne upirače na ključnim mjestima ako se izgube lateralni zubi kako bi se most mogao prenamijeniti u kombinirani rad s mobilnom protezom. Nedostatak zuba u mandibuli nadomješten je klasičnim fiksnim metalkeramičkim mostom., This clinical report describes a fixed maxillary telescopic dental prosthesis (FTDP) employing milled base metal copings and a metal superstructure veneered with composite resin, for the restoration in a periodontally compromised patient with uncontrolled diabetes. The telescopic prosthesis framework design incorporated occlusal rest seats in key positions along the arch in case of future posterior tooth loss, in order to be converted to fixed - removable combination prosthesis. The mandible was restored with a conventional fixed ceramo-metal dental prosthesis.

The aim of this qualitative study was to gain a deeper understanding of patient perceptions of wearing implant-retained overdentures with ball-shaped or cylindrical attachment systems. Twenty-two wearers of implant-supported overdentures participated in this qualitative study based on a randomized crossover clinical trial that aimed to compare a cylindrical attachment and a ball attachment. In phase I of the study, group A experienced ball attachments (n = 11) and group B Locator attachments (n = 11) for 1 year. Afterward, in phase II, the attachments were changed; group A received Locator attachments and group B received ball attachments. One week after the attachment's replacement, semistructured individual interviews were conducted. All interviews were audiotaped and transcribed. The analysis was guided by thematic content analysis. Most of the patients from both groups preferred the attachment they received in phase II, regardless the type. A major theme raised by the participants to justify their preference between the attachment types was prosthesis retention/stability, sometimes considered as a positive and other times as a negative factor. Other themes were also explored: oral function, pain, hygiene, previous experiences, confidence on the dentist's work, and esthetic. Aspects related to the retention/stability of the overdentures are the main concerns associated with the perceptions of most patients treated with implant overdentures regardless of the type of attachment. Adequate retention level should be identified and adjusted on an individual basis and maintained overtime as possible. Therefore, follow-up appointments should be planned for readjustment of the attachment's retention. Overretention should be avoided.

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 masticatory function of implant-retained overdentures with different attachments has not been sufficiently investigated. This study evaluated the masticatory function of implant-retained mandibular overdentures with ball and resilient telescopic attachments.Twelve edentulous participants were rehabilitated with new maxillary and mandibular conventional dentures (CD). Three months later, two implants were installed in the canine regions of the mandible. Following a 3-month healing period, duplicate overdentures were constructed for all patients. In a simple random method, six participants were first given ball-retained overdentures (BOD) and the other six received resilient telescopic-retained overdentures (TOD). After testing these prostheses, the first group received the TOD, while the second group received the BOD. Masticatory functions (chewing efficiency [unmixed fraction, UF] and electromyographic activity [EMG] of masseter muscles) were measured 3 months after wearing each of the following dentures: CD, BOD, and TOD. UF was measured using chewing gum and EMG was recorded for right and left bellies of masseter muscle during clenching with (soft and tough) and without foods.Regardless of attachment type, implant-retained overdentures demonstrated significant decrease in UF and significant increase in EMG compared to CD. TOD recorded significantly lower UF and significantly higher EMG when compared to BOD.The TOD improves masticatory functions when compared to BOD. Such improvement may be related to the increased retention and stability of these dentures.

Background IRRPD offers patients the ability to upgrade their treatment planning to implant-supported-overdentures (ISOs) or implant-supported-fixed-prostheses (ISFPs) through insertion of more implants in the future after the loss of the remaining natural teeth. Aims The purpose of this prospective-clinical-study was to evaluate the success rate and treatment outcome of IRRPD for 15 patients, during at least 5-year-follow-ups after prosthetic rehabilitation with respect to implant mobility, peri-implant-marginal-bone-levels, and prosthetic complications. Methods 15 successive patients were attended the Department of Implantology and Prosthodontics in TUMS, and received Implant-Retained-Removable-Partial-Dentures (IRRPDs). Two standard-size-dental-implants (Implantium/Dentium system, internal hexagon, Seoul, South Korea) were placed in distal-extension-areas for each patient. After the osseointegration period, all patients received IRRPDs using two Ball attachments. All the participated patients were followed-up at least for 5 years, and the survival rate of 30 implants was evaluated. The patients’ satisfaction of function, phonetics, and aesthetics was assessed by means of questionnaire. Results None of the studied patients reported any prosthetic complications during the follow-up-periods such as attachment loosening, metal housing loosening, or denture fracture. No implants failure was recorded, so that the cumulative-implant-survival rate was 100 per cent. The mean marginal-bone-resorption (MBR) around the two implants was 0.9mm with a range of 0.5–1.4mm. Teeth aesthetics was judged as excellent or very good by 86.7 per cent of the patients, while phonetics and mastication were considered excellent or very good by 66.7 per cent and 73.3 per cent of the patients, respectively. Conclusion 15 patients received 30 implants for the fabrication of IRRPDs in the posterior-edentulous-sites. The IRRPDs were delivered to the patients by the same practitioner. After 5-year-follow-ups-schedule, this prospective-clinical-study supported the use of IRRPDs in the posterior region when the patients cannot afford more implants insertion for the construction of ISFPs. Within the limitation of this study, the following conclusions can be drawn: 1. The survival rate of all 30 implants was 100 per cent. 2. No prosthetic complications were occurred during 5-year-follow-ups-period. 3. IRRPDs treatment option should be encouraged to be used in the posterior-edentulous-sites as an alternative option to ISFPs. 4. IRRPDs can provide appropriate function, phonetics, and aesthetics

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.

Purpose This in vitro study investigated the pressure distribution of the implant-supported removable partial dentures (RPDs) with the stress-breaking attachments under the occlusal force. Methods The experimental model of bilateral missing premolars and molars was modified from a commercial simulation model. Five pressure sensors were embedded near the bilateral first molars, first premolars, and medio-lingual alveolar crest. Two implants were placed near the second molars, and they were connected to the denture base using the following conditions: complete separation between the denture base and implant with cover screws (CRPD), flexible connection with a stress-breaking ball (SBB) attachment, and rigid connection without stress breaking with healing caps (HC). The pressure at five different areas of the soft tissue and the displacement of the RPDs were simultaneously measured, loading up to 50N. The coefficient of variation (CV) for each connection was calculated from all data of the pressure at five areas to evaluate the pressure distribution. Results The pressure on medio-lingual alveolar crest and molars of the HC was less than SBB and CRPD. In contrast, the pressure on premolars of SBB was greater than for the HC and CRPD. The CV of SBB was less than that of HC and CRPD. Denture displacement of HC and SBB was less than for CRPD. Conclusions Within the in vitro limitations, precise denture settlements and pressure distribution under the denture base could be controlled using an SBB attachment. An SBB attachment might be able to protect the implant from harmful force.

There have been demographic and cultural changes in the past few decades with regards to edentulism. Conventional mucosa-borne dentures can be poorly accepted by some patients. Implant overdentures have a useful role to play in the treatment of some of these patients. Some form of attachment mechanism between the implants and the prosthesis is normally required. This paper updates the reader on the different types of attachment systems and bars available. Clinical Relevance: It is important that dentists and technicians are able to understand the advantages and disadvantages of different attachment types for overdentures, in order to select the most appropriate technique for each patient.

Aim To investigate the importance of attachment types on the retention loss of extracoronal attachment-retained removable partial dentures depending on the usage period. Materials and methods In order to observe the retention loss of 5 different attachments (OT Strategy, OT Strategy-metal protected, Vario-stud-snap and Vario-soft 3 and ERA-RV) over time, attachment-retained partial dentures representing Kennedy II mod. I case were placed in a custom-made, retention test machine. For each minute, eight separating and joining movements were performed and retention values (Newton) of the attachments were recorded by computer. The retention tests implemented in 540,1080 and 2160 cycles. The data were evaluated statistically according to the two-way ANOVA and Tukey parametrical tests. Results The slide type attachment providing the best retention force was observed to be the most worn out by this process (p < 0.01) while the ball type attachments, which typically have the lesser retention force, showed less retention loss (p < 0.01). Conclusion It can be concluded that the retention attributes of the attachment-retained dentures were affected by the specific type of precision attachment as well as the usage period. Clinical significance Precision attachments with ball-type plastic matrices may be recommended for the clinical use due to their retention stability over time. How to cite this article Can G, Özmumcu B, Altinci P. In vitro Retention Loss of Attachment-retained Removable Partial Denture. J Contemp Dent Pract 2013;14(6):1049-1053.

The aim of this study was to evaluate and compare the clinical and radiographic outcomes of two implants placed in expanded mandibular knife-edge ridge and implants placed in unexpanded ridges to retain overdentures.Fifteen completely edentulous patients with knife-edge ridges at canine areas of the mandible received two implants using the ridge expansion technique (study group, SG). Expansion was performed using piezoelectric corticotomy, and self-threading expanders. The control group (CG) comprised patients who received two-implant at canine areas without ridge expansion but were all case matched to SG and served as historical cohort. In both groups, mandibular overdentures were connected to the implants with Locator attachments 3 months after implant placement. Clinical (Plaque index; PI, Gingival index; GI, Probing depth; PD, and implant stability; ISQ) and radiographic (Vertical bone loss; VBL) parameters were recorded at time of overdenture insertion (base line, T0), 6 months (T6), and 12 months (T12) after insertion.The cumulative success rates were 100% and 96.4% for CG and SG, respectively, without significant difference between groups. All tested parameters increased significantly with advance of time in both groups. There was no significant difference in PI, GI, PD, and ISQ between groups. However, SG recorded significant higher VBL than CG at T6 and T12.Expansion of mandibular knife edge ridge and simultaneous placement of implants to retain overdentures is associated with clinic and radiographic outcomes comparable to implants placed in unexpanded ridges after 1 year. However, long term randomized controlled trials with sufficient sample size are still needed to ensure the findings of the present study.

Being a secondary outcome in a multicenter randomized controlled trial, the present analysis focused on interdental spacing in the shortened dental arch (SDA). The aim was to evaluate changes in interdental spacing in dependence of two different treatments after an observation period of up to 5 years.Patients were either treated with a partial removable dental prosthesis (PRDP) for molar replacement (PRDP group) or according to the SDA concept aiming at a premolar occlusion (SDA group) in a randomized manner. Interdental spacing in the anterior region was measured with gauges and categorized as "0" (0.1 mm), "1" (0.5 mm), "2" (0.5-1 mm), and "3" (1 mm). The statistical analysis was performed with analysis of variance models followed by linear contrast.Ninety-one patients (SDA n = 41, PRDP n = 50) were included. Changes of interdental spacing were detected in 70.7 % of all cases. A significant difference between the mean score changes was found in the mandible comparing the PRDP group and the SDA group. The respective mean score changes from baseline to 5 years were 0.23 (SD 0.49) for the PRDP group and 0.02 (SD 0.30) for the SDA group (p = 0.023).Major interdental spacing could be observed in neither of the groups. The SDA concept resulted in a slightly better outcome.When deciding whether to replace missing molars, the present results give further support to the SDA concept.

Passively retained precision attachment removable partial dentures have been used successfully since the 1920s. Adult cleft palate patients and accident victims often have endured a lifetime of wearing awkward appliances to replace the missing structures that never formed intraorally or were lost in a traumatic accident. These patients tend to be poor candidates for dental implants, even with repeated grafting surgeries. The anterior double-tilt precision attachment case is a great treatment option for adults to restore the missing dental structures. Anterior precision partial dentures are stable appliances in the mouth that are worn 24 hours a day and only removed for hygiene. They can be custom designed for maximum esthetics. They do not require denture paste, and they extend minimally onto the palate. As a result, they do not interfere with musculature, tongue movements, speech and taste. Cleft palate patients and accident victims with poor or non-existent edentulous ridges will have difficulty retaining a denture, so preservation of the existing dentition is essential for comfort and function. Because these prostheses do not apply destructive forces to the abutment teeth, they can last decades with minimal maintenance.

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.

The study was designed to provide clinical outcome data for two treatments of the shortened dental arch (SDA). In a multicenter randomized controlled clinical trial, patients with complete molar loss in one jaw were provided with either a partial removable dental prosthesis (PRDP) retained with precision attachments or treated according to the SDA concept preserving or restoring a premolar occlusion. No implants were placed. The primary outcome was tooth loss. Of 152 treated patients, 132 patients reached the 5-year examination. Over 5 years, 38 patients experienced tooth loss. For the primary outcome tooth loss, the Kaplan–Meier survival rates at 5 years were 0.74 (95 % CI 0.64, 0.84) in the PRDP group and 0.74 (95 % CI 0.63, 0.85) in the SDA group. For tooth loss in the study jaw, the survival rates at 5 years were 0.88 (95 % CI 0.80, 0.95) in the PRDP group and 0.84 (95 % CI 0.74, 0.93) in the SDA group. The differences were not significant. No Cox regression models of appropriate fit explaining tooth loss on the patient level could be found. The overall treatment goals of a sustainable oral rehabilitation and the avoidance of further tooth loss over longer periods were not reliably achievable. The influence of the type of prosthetic treatment on tooth loss might have been overestimated. Regarding our results, the patient’s view will gain even more importance in the clinical decision between removable and fixed restorations in SDAs.

The scientific evidence concerning prosthodontic care for the shortened dental arch (SDA) is sparse. This randomized multicenter study aimed to compare two common treatment options: removable partial dental prostheses (RPDPs) for molar replacement vs. no replacement (SDA). One of the hypotheses was that the follow-up treatment differs between patients with RPDPs and patients with SDAs during the 5-year follow-up period. Two hundred and fifteen patients with complete molar loss in one jaw were included in the study. Molars were either replaced by RPDPs or not replaced according to the SDA concept. A mean number of 4.2 (RPDP) and 2.8 (SDA) treatments for biological or technical reasons occurred during the 5-year observation time per patient. Concerning the biological aspect, no significant differences between the groups could be shown, whereas treatment arising from technical reasons was significantly more frequent for the RPDP group. When the severity of treatment was analyzed, a change over time was evident. When, at baseline, only follow-up treatment with minimal effort is required, over time there is a continuous increase to moderate and extensive effort observed for both groups ( Controlled-trials.com number ISRCTN97265367).

Objectives Inlay-retained fixed partial dentures are conservative prosthetic restorations. Their failure resistance is influenced by the stress distribution that depends on the material properties as well as the loading conditions. Finite element analysis provides the ability to estimate the loading capacity by simulating the stress distribution in all-ceramic dental restorations. The null-hypothesis of this study was that tooth mobility or tooth bearing condition significantly influences the stress distribution and therefore the failure resistance of all-ceramic inlay-retained fixed dental prostheses. Therefore, the stress distribution under different loading and bearing conditions of the teeth was analyzed using the finite element method. Methods Three different bearing conditions, one fixed and two flexible were chosen to simulate tooth mobility. The flexible models were constrained with spring elements to a virtual center of rotation. In addition, loading conditions were varied. Results The influence of tooth mobility on the stress distribution depended on the degree of modeled tooth mobility, as well as the loading conditions. The maximum first principal stresses differed significantly in magnitude and location depending on the modeled bearing condition and the simulated load case. The maximum difference between fixed and flexible model was more than 100%. Significance Tooth mobility and occlusal loading conditions have to be considered in finite element analyses as the simulated stress distribution is strongly influenced by these factors.

Objectives The aim of this preliminary prospective study was to evaluate the clinical outcome, the oral health-related quality of life (OHRQoL), and the subjective chewing ability of patients with mandibular complete dentures retained by a single implant placed in the mandible midline. Methods Patients wearing complete dentures were treated with a single implant in the mandible, followed by relining of the dentures and incorporation of ball attachments for implant retention. Implant outcome, prosthodontic maintenance, subjective chewing ability, and the oral health impact profile of the patients were assessed at baseline and at four weeks after connecting the denture and implant. Results Eleven patients were enrolled in this investigation, and the mean observation period was 43.4 months (minimum period: 35, maximum period: 52 months). No implants were lost during observation period, but four dentures needed repair because of the fracture of the denture base in the midline area. A significant improvement was observed in the OHRQoL of the patients after the attachment of the mandibular dentures with a single midline implant. Furthermore, the subjective chewing ability of the patients was significantly improved after implant connection. Conclusions Within the limitations of this preliminary prospective clinical study, single implant-supported mandibular overdentures were a successful treatment option for older edentulous patients who showed improvements in their OHRQoL and chewing ability.

For older patients, clinicians should consider maintaining teeth and using functionally-orientated treatment strategies as an alternative to removable prostheses. When the remaining dentition has a poor prognosis, key teeth should be preserved as overdenture abutments and a gradual transition to edentulousness planned. Where complete dentures are provided, these can be retained using dental implants to overcome many of the problems associated with conventional replacement dentures. Clinical Relevance: The elderly population of today is better informed and more demanding of oral healthcare providers than previous generations. Clinicians should be aware of all the prosthodontic treatment options available for older patients.

Passively retained precision attachment partial dentures have been used successfully on natural tooth abutments since the 1920s. However, the dental profession has not advocated their use with implant abutments. When used in the passive manner that has proven successful on natural tooth abutments, precision attachment cases on implant abutments can be an excellent treatment option. This type of case has been used successfully for more than 17 years and offers tremendous advantages over the conventional overdenture approach to removal restorations on implant abutments.

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.

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:25:52Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:31:10Z : No. of bitstreams: 1 2-s2.0-84856147754.pdf: 110326 bytes, checksum: 9bfcf993554e5c8f4628b58b78ebc5f8 (MD5) Made available in DSpace on 2014-05-27T11:25:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-05-01 Aim: There is little information considering the framework association between cast clasps and attachments. The aim of this study was to evaluate the retention strength of frameworks match circumferential clasps and extra resilient attachment cast in three different alloys (cobalt-chromium, nickel-chromium titanium and commercially pure titanium), using two undercut (0.25 and 0.75 mm) and considering different period of time (0, 1/2, 1, 2, 3, 4 and 5 years). Methods: Using two metallic matrices, representing a partially edentulous mandibular right hemiarch with the first molar crown, canine root and without premolars, 60 frameworks were fabricated. Three groups (n = 20) of each metal were cast and each group was divided into two subgroups (n = 10), corresponding the molar undercut of 0.25 mm and 0.75 mm. The nylon male was positioned at the matrix and attached to the acrylic resin of the prosthetic base. The samples were subjected to an insertion and removal test under artificial saliva environment. Results: The data were analyzed and compared with ANOVAs and Tukey's test at 95% of probability. The groups cast in cobaltchromium and nickel-chromium-titanium had the highest mean retention strength (5.58 N and 6.36 N respectively) without significant difference between them, but statistically different from the group cast in commercially pure titanium, which had the lowest mean retention strength in all the periods (3.46 N). The association frameworks using nickel-chromium-titanium and cobalt-chromium could be used with 0.25 mm and 0.75 mm of undercut, but the titanium samples seems to decrease the retention strength, mainly in the 0.75 mm undercut. The circumferential clasps cast in commercially pure titanium used in 0.75 mm undercuts have a potential risk of fractures, especially after the 2nd year of use. Conclusion: This in vitro study showed that the framework association between cast clasp and an extra resilient attachment are suitable to the three metals evaluated, but strongly suggest extra care with commercially pure titanium in undercut of 0.75 mm. Clinical significance: Frameworks fabricated in Cp Ti tend to decrease in retentive strength over time and have a potential risk of fracture in less than 0.75 mm of undercut. Department of Prevention and Oral Rehabilitation FO-UFG, Goiás Department of Prosthodontics NYUCD, New York Department of Biomaterial and Biomimetics NYUCD, New York Department of Dental Materials and Prosthodontics FOA-UNESP, São Paulo Department of Dental Materials and Prosthodontics FORP-USP, São Paulo Department of Dental Materials and Prosthodontics FOA-UNESP, São Paulo

A 41-year-old man with cleft palate presented with a wide dehiscence and missing teeth. Six implants had been placed for fabrication of an overdenture, which was unsatisfactory. A bar was waxed and cast for connection to the implants; precision attachments were placed laterally for retention. A fixed partial denture was fabricated, and milled crowns were fabricated at the molar region to provide a guiding plane for insertion of a removable palatal obturator. Good swallowing and speech outcomes were achieved. This technique provided functional and esthetic benefits, enhanced oral hygiene, and improved the psychological condition of the patient.

PURPOSE: The purpose of this in vitro investigation was to measure the forces generated during the continuous seating and unseating of prefabricated attachment systems used to retain implant overdentures. MATERIALS AND METHODS: An experimental design consisting of interchangeable fixture mounts, a radially indexable fixture holder, and a materials testing systems (MTS) machine was used to measure forces generated during the insertion and removal of spherical stud attachments (Straumann, Inc, Waltham, WA). Three separate experiments were conducted measuring the seating and unseating forces of a vertically aligned patrix/matrix assembly, a 20 degrees angled patrix opposing a vertically positioned matrix, and a vertically positioned patrix opposing a 20 degrees angled matrix. For each patrix/matrix combination, three specimens were tested. Measurements were continuously recorded under reproducible conditions in the presence of artificial saliva. All specimens were subjected to 10,000 seating/unseating cycles. Statistical analysis was performed with rank analysis of variance (ANOVA) for a group comparison (alpha= 0.05). RESULTS: Results showed variability in the initial insertion and removal forces among experimental groups and among specimens within each experiment. A marked increase in the seating and unseating forces was recorded for all specimens during the first 300 cycles, followed by a gradual decrease in these forces. The exact p-values for the Kruskal-Wallis test showed no significant difference between the initial and final seating/unseating forces (p > 0.1) nor in the maximum seating/unseating forces (p > 0.6) among the three experimental groups. CONCLUSIONS: Spherical stud attachments exhibited consistent seating and unseating forces over 10,000 cycles. A 20 degrees angle between the patrix and matrix had no effect on the overall seating and unseating force values.

There has been an increase in the provision of implant-supported prostheses in patients unable to tolerate conventional dentures. Unfortunately, many patients are unable to benefit from this treatment option because of anatomical, medical or financial constraints. Magnet-retained overdentures represent a potential treatment option in many of these cases. This article describes the development, advantages, complications and clinical procedures associated with the provision of tooth-supported, magnet-retained overdentures.Conventional overdenture retention can be enhanced by the use of dental magnets. Clinical procedures are straightforward and magnets offer a number of advantages over other forms of precision attachment.

This paper outlines the evolution of precision attachment applications from partial denture retention to the implant-retained overdenture.Understanding precision attachments in the osseointegration era is essential to obtain optimal treatment outcomes with the new therapeutic methods available.

Implant treatment protocols for fully edentulous patients include implant-supported fixed restorations with a minimum of five to six implants or overdentures on two to four implants. However, implant placement in the posterior areas is sometimes not permitted by anatomic and/or financial restraints, or patients’ unwillingness to have extensive surgical procedures. The purpose of this case report is to present a treatment option where bilateral distal extension removable partial dentures (RPDs) are used in combination with anterior fixed implant prostheses with semi-precision attachments. The initial treatment plan of a 65-year-old female with failing dentition involved the fabrication of overdentures supported by four implants placed in the interforaminal area in both arches. Because of inadequate space for the retentive elements of the overdenture and the patient's objection to surgical procedures for the placement of additional implants to support a fixed restoration, the treatment plan was modified. Fixed ceramometal cement-retained implant restorations with semi-precision attachments adjacent to the distal abutments were fabricated in the maxilla and the mandible. Bilateral distal extension RPDs were placed in both arches. The patient's benefits were increased comfort, good esthetics in the anterior area, improved phonetics, and masticatory function. Retentive element maintenance requirements were similar to conventional RPDs. More extended controlled clinical studies are needed to establish the long-term success of this treatment option. CLINICAL SIGNIFICANCE Removable partial dentures may offer an attractive treatment option for an edentulous patient, as they may combine an FPD in the anterior segment with a removable appliance in the posterior areas. A satisfying restoration can be achieved with fewer implants.

Toward realizing the performance of functional and versatile dental magnetic attachments in the third generation required for individual prosthesis, it is important to control retentive characteristics of the attachments. For this purpose, three new types of magnetic attachment, i.e., split-pole type with a slant magnetization, modified split-pole type, and cylinder type, have been developed and evaluated in terms of the restoring force as well as the retentive force. The new attachments are designed to have high corrosion resistance, combining magnetic and nonmagnetic stainless steels and microlaser welding similar to the usual cup-yoke and sandwich-yoke types. It has been found that the two split-pole types have stronger restoring force and the cylinder type has weaker restoring force in comparison with the usual magnetic attachments. The attachments can be used properly and selectively according to individual requirement on abutment state and denture retention. As a result, the newly developed attachments may provide flexible retention performance useful for more effective and extensive applications of a magnetic attachment.

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)

To evaluate effects of a treatment taking into consideration esthetics, chewing, and oral health-related quality of life (OHRQoL) of two tooth replacement strategies for maxillary partially edentulous patients with clasp (C-RPD) and precision attachment (PA-RPD) retained removable partial dentures (RPD).The study included 150 patients (72 men, 78 women) who received maxillary RPDs; 88 patients received clasp and 62 patients received precision attachment retained RPDs. Patients completed three questionnaires before treatment and again 3 months after treatment: the Orofacial Esthetic Scale (OES), the Oral Health Impact Profile (OHIP-14), and the Chewing Function Questionnaire (CFQ). Statistical analysis comprised descriptive statistics, paired t-test, and two-factor ANOVA.Both RPD treatments yielded better after-treatment summary scores when compared with the baseline scores (p0.01); however, better results were obtained in the PA-RPD group. Gender, as a single factor, did not yield significant effects; mutual interaction of retention type and gender yielded significant effects. The PA-RPD female group assessed esthetics, chewing function, and OHRQoL significantly better than males, and significantly worse than males in the C-RPD group. The covariate baseline scores yielded statistically significant effects; patients with worse pretreatment condition benefited more from both therapies.Treatment outcomes were better in the PA-RPD group than the C-RPDs. Women showed greater concern for the treatment outcomes; their rates were significantly better than in male patients in the PA-RPD group; however, when their satisfaction was lower, their rates were significantly worse than in male patients (in the C-RPD group).

OBJECTIVE: The aim of this in vitro pilot study was to evaluate the influence of an artificial saliva (AS) lubricant on the retentive force of a stud-type attachment (LOCATOR(R) ) for implant overdentures (IODs). METHODS: Twenty custom-made models simulating a two-IOD with parallel implant situation were fabricated using LOCATOR(R) attachments. The in vitro testing was carried out with an Instron(R) universal testing machine for a total of 10,000 insertion-removal cycles, for each model, in two different aqueous test mediums (Group 1: 0.9% sodium chloride solution (NaCl), n = 10; Group 2: AS, n = 10). Changes in the mean retentive force (F) were plotted against the cycle numbers #10, #100, #1000, #5000, and #10,000. Mixed regression models were applied for statistical analyses. RESULTS: A mixed regression (not considering interactions) predicted, compared to cycle #10, higher retentive forces at cycles #100 (P < 0.0001), #1000 (P = 0.017), similar forces at #5000 (P = 0.277), and lower forces at #10,000 (P = 0.012); there was no overall effect of the medium (P = 0.159). A second statistical model, employing the interaction term "cycle##medium", confirmed similarly the effect. Although the interaction term was significant at cycle #100 (p = 0.045), there was no significant difference between the two groups (P = 0.140). CONCLUSION: In this in vitro pilot experiment, there was no difference in mean retentive forces of the LOCATOR(R) attachments when tested with either 0.9% NaCl or a Glandosane(R) -like artificial saliva lubricant. A larger scale study may still confirm the superiority of either lubricant for quasiclinical bench experiments.

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.

Introduction Overdentures supported and retained by endosteal implants depend upon mechanical components to provide retention. Ball attachments are frequently described because of simplicity and low cost, but retentive capacity of these components may be altered by a lack of implant parallelism. Purpose The aim of this in vitro study was to investigate the retention of gold and titanium overdenture attachments when placed on ball abutments positioned off-axis. Methods and materials Four ball abutments were hand-tightened onto ITI dental implants and placed in an aluminum fixture that allowed positioning of the implants at 0 degrees, 10 degrees, 20 degrees, and 30 degrees from a vertical reference axis. Gold and titanium matrices were then coupled to the ball abutments at various angles and then subjected to pull tests at a rate of 2 mm/second; the peak loads of release (maximum dislodging forces) were recorded and subjected to statistical analyses. A balanced and randomized factorial experimental design testing procedure was implemented. Results Statistically significant differences in retention of gold matrices were noted when ball abutments were positioned at 20 degrees and 30 degrees , but not at 0 degrees and 10 degrees. Statistically significant differences were noted among the titanium matrices employed for the testing procedure, as well as for the 4 ball abutments tested. Angle was not a factor affecting retention for titanium matrices. Conclusions (1) The gold matrices employed for the testing procedures exhibited consistent values in retention compared to titanium matrices, which exhibited large variability in retention. (2) Angle had an effect upon the retention of gold matrices, but not for titanium matrices.

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.

The creation of paralleled, milled surfaces in natural or restored abutment teeth, coupled with removable partial denture castings that have optimal contact with these preparations, results in a path of insertion and removal that is controlled in a manner similar to one using conventional precision attachments. Because the milled surfaces are primarily extracoronal, little if any, additional tooth reduction is required for adequate mouth preparation. Avoiding additional tooth reduction minimizes later abutment fracture. The great increase in stability and resistance to rotational movements, when combined with conventional posterior clasping, provides a reasonable alternative to the precision attachment in providing maximal esthetics for the partially edentulous patients.