Cast Removable Partial Dentures Research Articles

Treatment of Distal Extension Edentulous Arches with Attachment Retained Cobalt Chromium Partial Dentures-A Case Report

Background: The awareness and demand for quality of dental treatment is relatively increasing in recent generation and more so, as far as aesthetics are concerned, along with other functions of the prosthesis. In treating partially edentulous mouth, it requires more attention, principally for esthetics, in design. While achieving the goal, the components which are incorporated in removable partial denture may result in unsightly appearance. Case Description: A 77 year old patient reported to the replacement of his missing teeth for which a conventional maxillary complete denture and cast removable partial denture with precision attachments were planned to construct. Extra coronal resilient attachment was planned to re-claim support and thereby regain of lost esthetics in the mandibular arch. Conclusion: Use of precision attachment has amplified the aspects of retention and particularly, esthetics when compared to conventional removable partial dentures.

Postinsertion adjustment appointments and their association with cast removable partial denture survival

Statement of problemSuccessful outcomes with cast removable partial dentures (RPDs) are dependent on adequate fabrication and adjustments at the delivery appointment. Evaluation of the number and frequency of postinsertion follow-up appointments helps determine whether the prosthesis continues to fit comfortably and whether function and esthetics continue to be satisfactory. Reports on the number of appointments and frequency and type of adjustments required for RPDs following insertion are sparse. PurposeThe purpose of this university-based population study was to determine the number of appointments and type of adjustments following RPD insertion and their association with patient demographics, type of RPD, and denture survival. Material and methodsThis retrospective clinical study examined the records of 257 patients at the University of Toronto, Faculty Dentistry, wearing 308 RPDs inserted between 2013 and 2014 with a 5-year follow-up. The outcome measures investigated included postinsertion appointments, type of adjustments, and denture survival. ResultsA total of 48.1% of the dentures (19.5% tissue supported; and 28.6% tooth supported) were maxillary, and 51.9% (34.7% tissue supported; and 17.2% tooth supported) mandibular. Most patients (68.9%) had 1 to 3 postinsertion appointments, with 78.6% having no major adjustments. Twenty-six dentures failed (failure rate 8.4%), with the failure-free time estimated at 4.58 years (95% confidence interval (CI) 4.42-4.73 years, Kaplan-Meier survival analysis). Failed dentures were significantly associated with more minor adjustments (Mean (M)=4.12, SD=3.90, Kruskal-Wallis (K-W) P=.027; OR=1.18; 95% CI 1.05-1.32, P=.006). More minor adjustments were needed for mandibular dentures (multivariable Poisson regression (MPR) P=.003) compared with maxillary dentures. More major adjustments were needed for maxillary dentures (MPR P=.030) compared with mandibular dentures. More minor and major adjustments were needed for dentures that were remade from within 5 years to beyond 10 years compared with first time denture wearers (MPR P<.001). Patients with musculoskeletal disorders required a significantly higher number of minor adjustments (M=3.67, MPR P<.001) and appointments (M=3.87, MPR P<.001) than those without these disorders. ConclusionsThe 5-year survival of RPDs following insertion was estimated at 91.6%. Most patients required 1 to 3 appointments after insertion. Mandibular RPDs required significantly more minor adjustments, and maxillary RPDs more major adjustments. More minor and major adjustments were needed for dentures that were remade at any time previously compared with first time denture wearers.

Fatigue behavior of removable partial denture cast and laser-sintered cobalt-chromium (CoCr) and polyetheretherketone (PEEK) clasp materials.

To investigate the fatigue behavior of cast and laser-sintered cobalt-chromium (CoCr) and polyetheretherketone (PEEK) material for a removable partial denture (RPD) clasps. Dumbbell-shaped specimens were digitally designed with the center part of the dumbbell being a half-round shape at the cross-sectional dimension of 1.25 mm to simulate a typical clasp design and dimensions. A fatigue machine with an offset axis rotation system simulated a typical undercut depth of 0.25, 0.50, and 0.75 mm. Each group was subjected to 30,000 fatigue cycles (simulating 21 years) or till specimen failure. Before testing, the stress value at each undercut depth for each specimen was established in a universal testing machine and SN curves were plotted for each group. Data were statistically analyzed using Kruskal-Wallis and post hoc tests. The fractured surfaces were analyzed using SEM. The average fatigue cycles with 0.25, 0.50, and 0.75 mm undercuts were 27,155 ± 6277, 9298 ± 4033, 5642 ± 8785 for cast CoCr and 26,765 ± 6150, 11,318 ± 7931, 2861 ± 4803, for laser-sintered CoCr, respectively. Apart from three specimens, the PEEK groups did not fail during the simulation period. Clasps with 0.25 mm deflection showed significantly higher fatigue resistance than other groups (p < .001). There was no significant difference in fatigue behavior between the cast and laser-sintered CoCr. Microporosities at the fractured site along with irregular crack propagation were observed for cast and laser-sintered CoCr specimens. Fatigue-induced broken polymer crosslinking chains were observed in PEEK specimens. PEEK material exhibited the highest fatigue resistance and significantly lower deflection resistance. Cast and laser-sintered CoCr showed similar fatigue resistance and behavior.

FREQUENCY OF INADEQUATE DIMENSIONS OF OCCLUSAL REST SEAT PREPARED ON 2ND MOLAR ABUTMENTS FOR CAST REMOVABLE PARTIAL DENTURES

Objective: To evaluate occlusal rest seat preparations for cobalt chromium cast removable partial denture. Materials and Methods: A cross-sectional study was carried out in the department of Prosthodontics, Khyber College of Dentistry, Peshawar starting from June 2014 to June 2015 using consecutive non-probability sampling technique. Data was collected from 127 partially dentate patients having a bounded saddle with a distal abutment as second molar with normal occlusal surface morphology and mesio-occlusal rest seats prepared on the mentioned molar teeth. Patients having partially dentate areas with no principal abutment as second molar and rest seat other than mesio-occlusal rest seat were excluded from the study. Casts were evaluated for aspects of rest seat like the general outline form of the rest seat (visually assessed from the casts), the bucco-lingual and mesio-distal dimensions were measured using a divider and scale. Depth of the rest seat was measured by placing a piece of warm modelling wax with the casts in occlusion and measuring the thickness using Iwenson gauge. Data was analyzed using SPSS 20. Results: Out of 127 patients, mean age recorded was 38 years with Standard deviation ± 2.15. Males (62%, n=79) reported more than females (38%, n=48). The most frequently reported inadequate dimension was the depth of rest seat (46%, n=58), followed by the general outline form and mesio-distal width (40%, n= 51). The bucco-lingual dimension was recorded to be inadequate in 37% (n=47) of the cases. Conclusion: Most of The participants tend to under-prepare rest seat in terms of outline form, width, length and depth.

Comparison Between Altered Cast Impression and Conventional Single-Impression Techniques for Distal Extension Removable Dental Prostheses: A Systematic Review.

To systematically review the available literature and determine the potential benefits of altered cast impression technique over conventional single-impression techniques for the fabrication of distal extension removable dental prostheses. The indexed English literature published up to April 30, 2018, was systematically searched for studies comparing altered cast impression technique to conventional single-impression techniques for the fabrication of distal extension removable dental prostheses using guidelines recommended by Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA). The databases searched were PubMed, the Cochrane Library, and MEDLINE (OVID). Two reviewers independently screened and shortlisted the relevant studies based on predefined inclusion and exclusion criteria. Seven studies were included in this review; all were in vivo studies. All seven studies reported that cast removable partial dentures fabricated with altered cast impression technique displayed less vertical movement of denture bases compared to those fabricated using conventional impression techniques. Two of these studies reported that this difference in vertical movement was clinically insignificant, while the other five studies reported a statistically significant difference in vertical movement but were uncertain regarding clinical significance. The results of this literature review indicate that the altered cast impression technique did not offer significant advantages over conventional single-impression techniques. The lack of convincing data to predict superiority of the altered cast impression technique for distal extension removable dental prosthesis impressions emphasizes the need for more scientific research with larger sample sizes and longer performance reviews of removable dental prostheses.

Functional rehabilitation of edentulous mandible with cast removable partial denture: A Case report

Functional rehabilitation of edentulous mandible with cast removable partial denture: A Case report

Functionally generated pathways to develop occlusal scheme for removable partial denture

The functionally generated pathway (FGP) technique consists of registering the occlusal pathways of the posterior teeth in the functional wax and has been classically described as the three-dimensional static expression of dynamic tooth movement. This clinical report describes the treatment of a partially edentulous patient, with a cast removable partial denture, in which occlusion was developed using the FGP procedure. The FGP technique utilizes the patient's masticatory system to develop occlusion and has the advantages of being simple, accurate, and reliable. If the FGP technique is properly accomplished, only minor intraoral occlusal adjustments are necessary. This article described a technique of developing the FGP occlusion for a patient with cast partial denture with Kennedy's Class III edentulous mandibular arch. CLINICAL RELEVANCE TO INTERDISCIPLINARY DENTISTRY The FGP is highly versatile technique of developing the occlusion-pattern in the removable and fixed dental prostheses including implant restorations. It can be employed with equal efficacy in fabrication of relatively simple restorations such as a single crown, or more complex full mouth reconstructions.

Effect of storage time and framework design on the accuracy of maxillary cobalt-chromium cast removable partial dentures.

Statement of Problem:Inaccuracies in the fit of palatal major connectors may be related to distortion of the wax pattern due to prolonged storage time and faulty major connector design.Purpose:This in vitro study was carried out to find out the effect of storage time and major connector design on the accuracy of cobalt-chromium cast removable partial dentures (RPDs).Materials and Methods:A brass metal die with a Kennedy Class III, modification 1, the partially edentulous arch was used as a master die. Thirty-six refractory casts were fabricated from the master die. The refractory casts were divided into three groups (Group I: Anterior-posterior palatal bar, Group II: Palatal strap and Group III: Palatal plate) based on the design of maxillary major connector and subdivided into four groups (sub Group A: 01 h, sub Group B: 03 h, Sub Group C: 06 h, and sub Group D: 24 h) based on the storage time. For each group, 12 frameworks were fabricated. The influence of wax pattern storage time and the accuracy of the fit palatal major connector designs on the master die were compared. Casting defects (nodules/incompleteness) of the frameworks were also evaluated before finishing and polishing. Repeated measures analysis of variance was used to analyze the data.Results:The gap discrepancy was least in sub Group A (01 h) followed by sub Group B (03 h) and C (06 h) and most in sub Group D (24 h). Statistically significant differences (P < 0.05 in all locations L1–L5) in the fit of the framework were related to the design of the major connector. The gap discrepancy was least in Group I (anterior-posterior palatal bar) followed by Group II (palatal strap) and most in Group II (palatal plate).Conclusions:It is recommended that the wax patterns for RPD to be invested immediately on completion of the wax procedure. The selection of a major connector design is crucial for an accurate fit of RPD.

Cast removable partial denture improving appearance and masticatory function - A case report

Dentists are disappointed after delivery of cast removable partial dentures because their patient refuses or is unable to wear the denture and the treatment is therefore deemed unsuccessful. When so many patients do not comply with treatment, it is instructive to reflect on why and how the treatment is performed. Appropriate, comprehensive treatment planning should precede and eliciting the patient's chief complaint, as well as his or her expectations of treatment before treatment planning. The case presentation provides for the practitioner to discuss the patient's expectations and to outline both favourable and unfavourable short and long term outcomes. By providing this information, the practitioner ensures that the patient is fully informed before giving consent and that he or she understands the associated benefits and risks. DOI: http://dx.doi.org/10.3329/updcj.v1i1.13948 Update Dent. Coll. j: 2011; 1 (1): 14-17

Extracoronal precision attachments in a patient with generalized tonic-clonic seizures

Epilepsy is caused by a number of genetic, physiological and infectious disorders as well as by trauma. In 70% of patients the epilepsy is well controlled by antiepileptic drugs but the disease itself and the pharmaceutical management often have an impact on the oral cavity. Primary management considerations are the provision of good periodontal care and the restoration of the teeth with stable, strong restorations. Epileptic patients have differing needs when developing plans for prosthodontic treatment. Treatment should be individually tailored, considering the type and severity of the disease with special emphasis on the type and frequency of seizures. This case report describes the prosthodontic rehabilitation of a generalized tonic-clonic convulsive patient for missing mandibular anterior teeth with a precision attachment cast removable partial denture.

Cast Removable Partial Denture Rubric

Abstract This resource is a rubric designed for a preclinical removable partial denture prosthodontics course that consists of weekly lectures followed by laboratory sessions. The rubric consists o...

Direct retainers: Esthetic solutions in the smile zone

Direct retainers are the essential components of cast removable partial dentures. However, their presence and acute visibility, when the patient smiles, can be a sore to the eye. The unaesthetic appearance of the direct retainer is a vexing problem that dentists in general and the patient in particular have to contend with. Presented herein is a literature review of the various means to either eliminate or minimize their display when the patient bears a smile.

Comparison of cast Ti-Ni alloy clasp retention with conventional removable partial denture clasps

Statement of problem The elastic property of Ti-Ni alloy may be a desirable property for cast removable partial dentures. However, little is known about the retentive properties of cast Ti-Ni alloy clasps. Purpose This in vitro study investigated the retentive force of various types of clasps during repeated cycles of placement and removal to determine whether Ti-Ni alloy clasps maintain their initial retentive force under varied conditions, including different retentive undercut depths and clasp size (thickness and width). Material and methods The test models were developed using a mandibular dentiform with a horizontal plane of occlusion. Two complete metal abutment crowns were made for the left second molar, differing only in retentive undercut depths. A total of 98 clasps (n=7) were fabricated, including 14 wrought wire clasps and 28 clasps from each of the following alloys: Co-Cr alloy (Biosil), Type IV gold alloy (Cast-4), and Ti-Ni alloy (TN-10). Clasps were made to engage one of 2 retentive undercut depths (0.25 mm or 0.75 mm) and were made in 2 sizes (0.8 mm or 1.4 mm). Each clasp was radiographically examined for casting defects and porosity. The force (N) required to remove the clasps was measured using a universal testing machine with a crosshead speed of 10 mm/min. After measuring the retentive force, a masticatory simulator was used to cycle the clasps on and off the metal crown 500 times, simulating the insertion and removal of a removable partial denture clasp. The cycling sequence was repeated 10 times, and retention force was measured after each sequence. The internal surface of the clasp arms was examined for evidence of metal fatigue using scanning electron microscopy. Data were subjected to 2-way and 4-way analysis of variance, followed by Scheffe's multiple comparison test (α=.05). Results Co-Cr alloy and gold alloy clasps in the 0.25-mm retentive undercut groups experienced a gradual decrease in retentive force measurements ( P<.001). In contrast, the Ti-Ni alloy clasps maintained a retentive force of approximately 1.8 N and 2.6 N for the 0.8 mm and 1.4 mm clasp groups, respectively. Although Ti-Ni alloy clasps' retentive force was reduced slightly after the first cycling sequence, it was negligible compared with other clasps tested. The wrought wire clasps also retained their retentive force until the final cycling sequence. A similar trend was found in the clasp groups engaging 0.75-mm retentive undercuts. Conclusion Although the end-point retention for all the clasps was similar, there was less change in the retentive force of the cast Ti-Ni alloy clasps after repeated cycling sequences of simulated placement and removal.

Proximal plate in conventional circumferential cast clasp retention

Improper guiding planes are commonly used with conventional removable partial denture cast clasps. Short guiding planes with improper proximal plates decrease retention and cause repetitive traumatic movement of abutments. This article discusses the importance of guiding planes and proximal plates for conventional tooth-supported removable partial dentures with circumferential clasp. The retention force of the clasps was analyzed geometrically. If the guiding plane is short or the prepared surface is oblique, the contact between the proximal plate and the guiding plane or oblique plane diminishes at an early stage, which results in reduction of retention. The guiding plane should be parallel to the path of insertion and must be of a certain length for adequate retention. An elongated proximal plate that is parallel to the path of insertion may compensate for retention deficiency when an adequate guiding plane cannot be prepared. (J Prosthet Dent 2000;83:319-22.)

Pattern waxes and inaccuracies in fixed and removable partial denture castings

It is the desire of every dentist and dental technician to produce a restoration that will fit the patient with a minimum of adjustments and certainly one that does not require remaking. Yet many abuse the materials with which they work, either through improper manipulation, lack of familiarity with their properties, or by attempting to reduce laboratory time by taking short cuts. Wax is one of the materials that requires more knowledge and skill to manipulate accurately because it has a considerably higher coefficient of thermal expansion (and contraction) than any other dental material. It often contributes considerably to the inaccuracies of cast dental restorations. This article provides a review of dental waxes used to make prosthodontic castings and points out some of the properties of waxes that must be controlled to make accurate restorations. (J Prosthet Dent 1997;77:553-5.)

Sprue design in removable partial denture casting

Objectives: Correct sprue design is a major factor in the reduction of defects in castings of cobalt-chromium alloy. The purpose of this study was to investigate the sprue arrangements decided by a group of dental technicians, for a series of proposed removable partial denture castings, in order to determine if there was any consistency between them which would suggest the application of criteria in their design. Methods: Information was gathered by postal inquiry with recipients asked to indicate their sprue designs on diagrams of patterns for proposed cobalt-chromium partial denture castings. Results: Replies were received for 260 proposed castings from dental schools, technical colleges and commercial laboratories which gave an overall response rate of 52%. Results displayed a wide range of responses in relation to sprue number and dimension, attachment site and the intended direction of metal flow. Conclusion: It was concluded that the group of technicians studied arbitrarily chose sprue arrangements for the castings proposed rather than following definite design criteria that seek to minimize potential problems during casting procedures.

Gold alloy cast to base metal removable partial denture frameworks

For many years, gold and base metal alloys have been used in the construction of cast removable partial dentures. Each alloy has desirable properties, yet neither is ideally suited for all portions of a framework. A method has been developed to fabricate prostheses by casting gold alloy against a base metal alloy. This procedure allows the practitioner to combine the favorable characteristics of both alloys within a single framework. Consequently, the practitioner may create frameworks that more effectively meet the biomechanical demands of the oral environment.

The effect of reducing the number of clasps on removable partial denture retention

Retention to a master model of 10 nominally identical chrome-cobalt removable partial denture castings with standardized bilateral molar and premolar clasps engaging 0.25 mm (0.01 inch) undercuts and 10 castings with clasps engaging 0.5 mm (0.02 inch) undercuts was measured on an Instron testing machine. The retention of each framework was remeasured as the clasps were removed in one of two sequences. Differences between frameworks, number of clasps, and depth of undercuts were all significant. The order of removal of the clasps was not statistically significant. In a separate experiment the position of the dislodging force was found to be significant. It was concluded that the dislodging force was dependent on (1) the fit of the framework, (2) the depth of the undercut, (3) the number of clasps, and (4) its point of application.

Index to reposition the metal framework accurately on the altered cast

The relieved portion of a master cast below the major connector of a cast removable partial denture framework can be filled with dental stone to act as a third point of reference when the framework is reseated in an altered cast procedure. With this simple procedure, an index is formed that will allow accurate repositioning of the metal framework on the altered cast.

Ulcerative lesions of the palate associated with removable partial denture castings

Regions of inflammation with or without ulceration beneath removable partial dentures have been of concern to prosthodontists for many years. The etiology of these lesions has not been established, but potential factors are microbial infection, obstructive sialadenitis, and allergic-type reactions to the metal framework. A new etiological factor that may be involved is described. Focal pitting corrosion and by-products of corrosion in nickel-chromium alloys are discussed as toxic agents responsible for palatal lesions. Six patient reports that include results of tissue biopsy and EDAX analysis of casting are presented.