Evaluation of Stress Patterns Produced by Implant-Retained Overdentures and Implant-Retained Fixed Partial Denture

The purposes of this study were to photoelastically measure the biomechanical behavior of 4 implants retaining different cantilevered bar mandibular overdenture designs and to compare a fixed partial denture (FPD). A photoelastic model of a human edentulous mandible was fabricated, which contained 4 screw-type implants (3.75 x 10 mm) embedded in the parasymphyseal area. An FPD and 3 overdenture designs with the following attachments were evaluated: 3 plastic Hader clips, 1 Hader clip with 2 posterior resilient cap attachments, and 3 ball/O-ring attachments. Vertical occlusal forces of 100 N were applied between the central incisor and unilaterally to the right and left second premolars and second molars. Stresses that developed in the supporting structure were monitored photoelastically and recorded photographically. The results showed that the anterior loading, the overdenture with 3 plastic Hader clips, displayed the largest stress concentration at the medium implant. With premolar loading, the FPD and overdenture with 3 plastic Hader clips displayed the highest stresses to the ipsilateral terminal implant. With molar loading, the overdenture with 3 ball/O-ring attachments displayed the most uniform stress distribution in the posterior edentulous ridge, with less overloading in the terminal implant. It was concluded that vertical forces applied to the bar-clip overdenture and FPD created immediate stress patterns of greater magnitude and concentration on the ipsilateral implants, whereas the ball/O-ring attachments transferred minimal stress to the implants. The increased cantilever in the FPD caused the highest stresses to the terminal implant.

Photoelastic Analysis of Biomechanical Behavior of Single and Multiple Fixed Partial Prostheses With Different Prosthetic Connections

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Microstrain Around Dental Implants Supporting Fixed Partial Prostheses Under Axial and Non-Axial Loading Conditions, In Vitro Strain Gauge Analysis

The current study used strain gauge analysis to perform an in vitro evaluation of the effect of axial and non-axial loading on implant-supported fixed partial prostheses, varying the implant placement configurations and the loading points. Three internal hexagon implants were embedded in the center of each polyurethane block with in-line and offset placements. Microunit abutments were connected to the implants using a torque of 20 N.cm, and plastic prosthetic cylinders were screwed onto the abutments, which received standard patterns cast in Co-Cr alloy (n = 10). Four strain gauges (SGs) were bonded onto the surfaces of the blocks, tangentially to the implants: SG 01 mesially to implant 1, SG 02 and SG 03 mesially and distally to implant 2, respectively, and SG 04 distally to implant 3. Each metallic structure was screwed onto the abutments using a 10-N.cm torque, and axial and non-axial loads of 30 kg were applied at 5 predetermined points. The data obtained from the strain gauge analyses were analyzed statistically through the repeated measures analysis of variance and the Tukey test, with a conventional level of significance of P < 0.05. The results showed a statistically significant difference for the loading point (P = 0.0001), with point E (nonaxial) generating the highest microstrain (327.67 mu epsilon) and point A (axial) generating the smallest microstrain (208.93 mu epsilon). No statistically significant difference was found for implant placement configuration (P = 0.856). It was concluded that the offset implant placement did not reduce the magnitude of microstrain around the implants under axial and non-axial loading conditions, although loading location did influence this magnitude.

Removable Partial Dentures: Use of Rapid Prototyping

The CAD/CAM technology associated with rapid prototyping (RP) is already widely used in the fabrication of all-ceramic fixed prostheses and in the biomedical area; however, the use of this technology for the manufacture of metal frames for removable dentures is new. This work reports the results of a literature review conducted on the use of CAD/CAM and RP in the manufacture of removable partial dentures.

Quality of life and satisfaction of patients wearing implant-supported fixed partial denture: a cross-sectional survey of patients from Aracatuba city, Brazil

ObjectivesThe aim of this study was to evaluate the quality of life and satisfaction of patients wearing implant-supported fixed partial dentures.Materials &methodsA total of 106 patients were selected and submitted to clinical examination and collection of the demographic data for evaluation of the implant-supported fixed dentures conditions. All participants agreed to answer to the Oral Health Impact Profile (OHIP-EDENT) questionnaire and another questionnaire about satisfaction with the implant-supported prostheses. The patients were classified into the following three groups for statistical analysis: patients wearing splinted implant-supported prosthesis (E), patients wearing single implant-supported prosthesis (U), and patients wearing single implant-supported prosthesis associated with splinted prosthesis (E+U). Kruskal-Wallis test was used to compare the answers between the groups, and a logistic regression model was measured to verify the relation between variables of the patients and the questionaries'items.ResultsThere were significant differences among groups (P=0.006) for discomfort during surgery itself of the satisfaction questionnaire. The marital status, groups, and hygiene condition were significant mainly for physical pain item.ConclusionsIt was concluded that the patients presented high level of satisfaction and quality of life for the most of the items evaluated as well as the groups showed similar results.

Oral rehabilitation with implantations: association of fixed partial prosthesis, UCLA system, and EsthetiCone

The objective of modern odontology is to reconstitute to the patient the comfort, the function, the aesthetic form, the phonetic capability, and normal health. However, the more the patient is toothless, the more this objective becomes difficult inside traditional dentistry. As a result of continuous research of materials and techniques, permissible success is now a reality, whitewashing many challenging clinical situations. Thus, the objective of the article was to present a clinical case where association of the universal cast to long abutment pillars and EsthetiCone were used for aesthetic whitewashing. A man presented to the clinic of the Faculty of Dentistry, Universidade Estadual Paulista. After clinical examination and radiographic evaluation evidenced the necessity of substitution of fixed prostheses (15-25), he was presented with disadaptation and a favorable aesthetic solution. Ahead of the evaluated picture and considering the extension of the toothless space made, it was opted more, to the accomplishment of surgery, the setting of 2 implantations in the region and 2 in each edentate side of the posterior portion of the jaw. On 6 implants and 2 teeth, 10 metal ceramic crowns had been confectioned: 4 of them being joined in the region of the 12 to the 22 and the other 6 as unit crowns in the region of the 13, the 14, the 15, the 23, the 24, and the 25. The carried-through treatment was capable to return the aesthetic form, the function, the phonetic capability, the comfort, and the health of the verbal socket.

Distal extension removable partial denture with resilient attachment connect to an anterior fixed implant-supported prosthesis: a clinical report

Background: Considering the limited qualitative and quantitative bone in the posterior arch, this modality of prosthetic treatment could provide a positive emotional factor reestablished by immovability of the anterior fixed implant-supported segment. Objective: This clinical report demonstrates the possibility of achieving positive results with a removable partial denture connected to an implant-supported fixed prosthesis associated to an extra resilient attachment. Clinical significance: In cases of posterior mandibular and maxilla atrophy added to the patients desire against the bone graft, this kind of prosthetic treatment has an important place as an alternative.

Esthetic Interim Acrylic Resin Prosthesis Reinforced with Metal Casting

Fabrication of an interim prosthesis is an important procedure in oral rehabilitation because it aids in determining the esthetics, phonetics, and occlusal relationship of the definitive restoration. The typical material (acrylic resin) used in interim prostheses commonly fails due to fractures. During extended oral rehabilitation with fixed partial prostheses, high strength interim prostheses are often required to protect hard and soft tissues, avoid dental mobility, and to allow the clinician and patient a chance to evaluate cosmetics and function before the placement of the definitive prosthesis. Furthermore, a satisfactory interim prosthesis can serve as a template for the construction of the definitive prosthesis. The maintenance of this prosthesis is important during treatment for protection of teeth and occlusal stability. Procedures to reinforce interim prostheses help to improve performance and esthetics in long-term treatment. Due to the low durability of acrylic resin in long-term use, the use of reinforcing materials, such as metal castings or spot-welded stainless steel matrix bands, is indicated in cases of extensive restoration and long-term treatment. This paper describes an easy technique for fabricating a fixed interim prosthesis using acrylic resin and a cast metallic reinforcement.

Periodontal ligament influence on the stress distribution in a removable partial denture supported by implant: a finite element analysis

Objective: The non-homogenous aspect of periodontal ligament (PDL) has been examined using finite element analysis (FEA) to better simulate PDL behavior. The aim of this study was to assess, by 2-D FEA, the influence of non-homogenous PDL on the stress distribution when the free-end saddle removable partial denture (RPD) is partially supported by an osseointegrated implant. Material and Methods: Six finite element (FE) models of a partially edentulous mandible were created to represent two types of PDL (non-homogenous and homogenous) and two types of RPD (conventional RPD, supported by tooth and fibromucosa; and modified RPD, supported by tooth and implant [10.00x3.75 mm]). Two additional FE models without RPD were used as control models. The non-homogenous PDL was modeled using beam elements to simulate the crest, horizontal, oblique and apical fibers. The load (50 N) was applied in each cusp simultaneously. Regarding boundary conditions the border of alveolar ridge was fixed along the x axis. The FE software (Ansys 10.0) was used to compute the stress fields, and the von Mises stress criterion (sigma vM) was applied to analyze the results. Results: The peak of sigma vM in non-homogenous PDL was higher than that for the homogenous condition. The benefits of implants were enhanced for the non-homogenous PDL condition, with drastic sigma vM reduction on the posterior half of the alveolar ridge. The implant did not reduce the stress on the support tooth for both PDL conditions. Conclusion: The PDL modeled in the non-homogeneous form increased the benefits of the osseointegrated implant in comparison with the homogeneous condition. Using the non-homogenous PDL, the presence of osseointegrated implant did not reduce the stress on the supporting tooth.

Flexural Strength of Four Adhesive Fixed Dental Prostheses of Composite Resin Reinforced with Glass Fiber

Purpose: To evaluate the flexural strength of two fixed dental prosthesis (FDP) designs simulating frameworks of adhesive fixed partial prostheses, reinforced or not by glass fiber.Materials and Methods: Forty specimens, made with composite resin, were divided into 4 groups according to the framework design and the presence of fiber reinforcement: A1 - occlusal support; A2: occlusal support + glass fiber; B1: occlusal and proximal supports; B2: occlusal and proximal supports + glass fiber. The specimens were subjected to the three-point bending test, and the data were submitted to two-way ANOVA and Tukey's test (5%).Results: Group A2 (97.9 +/- 38 N) was statistically significantly different from all other experimental groups, presenting a significantly lower mean flexural strength.Conclusion: The use of glass fibers did not improve the flexural strength of composite resin, and designs with occlusal and proximal supports presented better results than designs simulating only occlusal support.

Characterization of ceramic powders used in the inCeram systems to fixed dental Prosthesis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Overlay removable partial dentures for a patient with ectodermal dysplasia: A clinical report

The orofacial characteristics of ectodermal dysplasia include anodontia or hypodontia, hypoplastic conical teeth, underdevelopment of the alveolar ridges, frontal bossing, a depressed nasal bridge, protuberant lips, and hypotrichosis. Patients with this disease often need complex prosthetic treatment. The options for a definitive treatment plan may include fixed, removable, or implant-supported prostheses, singly or in combination. However, financial constraints and other priorities can prevent patients from choosing the most desirable treatment. This clinical report describes the diagnosis and treatment of ectodermal dysplasia in an 18-year-old man. The treatment included interim removable partial dentures fabricated to establish an acceptable therapeutic occlusal vertical dimension, followed by definitive overlay removable partial dentures and composite restorations.

Clinical evaluation of abutment teeth of removable partial denture by means of the Periotest method

Prosthodontics should be one of the means of establishing conditions for the maintenance of periodontal health. The forces applied to the abutment teeth and their effects are very important considerations in the design and construction of the removable partial dentures. This 6-month follow-up clinical study evaluated the degree of mobility of abutment teeth of distal extension and tooth supported removable partial dentures by using Periotest. Two types of clasp design were selected for evaluation. In cases with unilateral and bilateral distal-extension, a clasp design including a T clasp of Roach retentive arm, a rigid reciprocal arm and a mesial rest were used. For the abutments of tooth-supported removable partial dentures, a second clasp design with a cast circumferential buccal retentive arm, a rigid reciprocal clasp arm and a rest adjacent to the edentulous ridges was selected. A total of 68 abutment teeth was analysed. Periotest values were made at the time of denture placement (control) and at 1, 3 and 6 months after the denture placement. The statistical analysis was performed using Friedman test. All analysis was performed at a 0.05 level of significance. The results revelled that no significant changes in tooth mobility were observed during the 6-months follow-up (P > 0.05). In conclusion, our findings suggest that adequate oral hygiene instructions, careful prosthetic treatment planning and regular recall appointments play an important role in preventing changes in abutment tooth mobility caused by removable partial denture placement.

Dual path: A concept to improve the esthetic replacement of missing anterior teeth with a removable partial denture

The dual path of insertion concept for removable partial denture (RPD) design may be used in esthetically demanding situations. When compared to conventional RPDs, the main advantage of this design is the minimal use of clasps. This clinical report describes the treatment of a patient with an anterior maxillary edentulous area using a dual path RPD. The diagnostic cast was surveyed to ensure the adequacy of the undercuts on the mesial surfaces of the anterior abutments, where rigid minor connectors were placed. Inverted V-shaped canine cingulum rest seats were prepared to provide resistance to tooth movement during function. The dual path RPD concept allows excellent esthetic results, minimizes tooth preparation, and reduces the tendency toward plaque accumulation in a Kennedy class IV partially edentulous arch. © 2008 by The American College of Prosthodontists.