Planning for Immediate Loading of Implant-Supported Prostheses: Literature Review

The aim of this study was to present the factors that influence planning for immediate loading of implants through a literature review for treatment success. Research was conducted in the PubMed database including the key words immediate implant loading, implant-supported prostheses, and implant planning for studies published from 2000 to 2011. Forty-eight articles were used in this review to describe the indications and counterindications, presurgical planning, and technologies available for planning of this treatment alternative.

Influence of Cusp Inclination on Stress Distribution in Implant-Supported Prostheses. A Three-Dimensional Finite Element Analysis

Purpose: The aim of this study was to assess the influence of cusp inclination on stress distribution in implant-supported prostheses by 3D finite element method.Materials and Methods: Three-dimensional models were created to simulate a mandibular bone section with an implant (3.75 mm diameter x 10 mm length) and crown by means of a 3D scanner and 3D CAD software. A screw-retained single crown was simulated using three cusp inclinations (10 degrees, 20 degrees, 30 degrees). The 3D models (model 10d, model 20d, and model 30d) were transferred to the finite element program NeiNastran 9.0 to generate a mesh and perform the stress analysis. An oblique load of 200 N was applied on the internal vestibular face of the metal ceramic crown.Results: The results were visualized by means of von Mises stress maps. Maximum stress concentration was located at the point of application. The implant showed higher stress values in model 30d (160.68 MPa). Cortical bone showed higher stress values in model 10d (28.23 MPa).Conclusion: Stresses on the implant and implant/abutment interface increased with increasing cusp inclination, and stresses on the cortical bone decreased with increasing cusp inclination.

Influence of the Connector and Implant Design on the Implant-Tooth-Connected Prostheses

Purpose:The purpose of this study was to evaluate stress transfer patterns between implant-tooth-connected prostheses comparing rigid and semirigid connectors and internal and external hexagon implants.Materials and Methods:Two models were made of photoelastic resin PL-2, with an internal hexagon implant of 4.00 x 13 mm and another with an external hexagon implant of 4.00 x 13 mm. Three denture designs were fabricated for each implant model, incorporating one type of connection in each one to connect implants and teeth: 1) welded rigid connection; 2) semirigid connection; and 3) rigid connection with occlusal screw. The models were placed in the polariscope, and 100-N axial forces were applied on fixed points on the occlusal surface of the dentures.Results:There was a trend toward less intensity in the stresses on the semirigid connection and solid rigid connection in the model with the external hexagon; among the three types of connections in the model with the internal hexagon implant, the semirigid connection was the most unfavorable one; in the tooth-implant association, it is preferable to use the external hexagon implant.Conclusions:The internal hexagon implant establishes a greater depth of hexagon retention and an increase in the level of denture stability in comparison with the implant with the external hexagon. However, this greater stability of the internal hexagon generated greater stresses in the abutment structures. Therefore, when this association is necessary, it is preferable to use the external hexagon implant.

Photoelastic Analysis of Cemented or Screwed Implant-Supported Prostheses With Different Prostheses Connections

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

Longitudinal study of the influence of removable partial denture and chemical control on the levels of Streptococcus mutans in saliva

Some studies have evaluated the salivary levels of mutans streptococci (MS) in removable partial denture (RPD) users. Saliva samples (2.0 mL) were obtained from 31 patients in six periods: (T0): immediately before installation of RPD; (T8): 8 days after T0; (T48): 48 days after T0; (T92): 92 days after T0; (T140): 140 days after T0 and (T189): 189 days after T0. The samples were vortexed and serially diluted from 10(-1) to 10(-6) in 0.05 m phosphate buffer (pH 7.4). From each dilution, 0.025 mL was plated on Mitis Salivarius Bacitracin (MSB). The plates were incubated in 5% CO2 at 37 degreesC for 72 h. There was an increase (t -test, P < 0.05) in the number of MS between periods T0 and T48 (mean/s.d., CFU mL(-1) of saliva): T0: 2.26/4.43 x 10(6) and T48: 0.47/1.48 x 10(8) . After this, intensive treatment with CHX was accomplished in 29 patients. Saliva samples were obtained after treatment in four periods: (T24 h): 24 h after T0; (T14): 14 days after T24 h; (T28): 28 days after T24 h, and (T63): 63 days after T24 h. The number of MS in saliva did not decrease (t -test, P > 0.05). A new CHX formulation was applied in 15 patients. Saliva samples were obtained in periods: (T0): before new CHX application; (T24 h): 24 h after T0 and (T82): 82 days after T0. The new CHX reduced MS levels in saliva: (mean/s.d., CFU mL(-1) of saliva): T0: 6.64/8.47 x 10(6) and T24 h: 3.2/4.27 x 10(5) (sign rank, P < 0.05). In conclusion, there was a significant increase in the number of MS in saliva after the installation of RPD. The intensive treatment with a properly formulated CHX was effective in the reduction of MS, between 24 h and 82 days after its application.

Orbital Implants Insertion to Improve Ocular Prostheses Motility

The objectives of this study were, through a literature review, to point the differences between orbital implants and their advantages and disadvantages, to evaluate prosthesis motility after orbital implants are inserted, and to point the implant wrapping current risks. Sixty-seven articles were reviewed. Enucleation implants can be autoplastics or alloplastics and porous (including natural and synthetic hydroxyapatite [HA]) or nonporous (silicone). Hydroxyapatite is the most related in the literature, but it has disadvantages, too, that is, all orbital implants must be wrapped. Exposure of the porous orbital implant can be repaired using different materials, which include homologous tissue, as well as autogenous graft, xenograft, and synthetic material mesh. The most used materials are HA and porous polyethylene orbital implant. The HA implant is expensive and possibly subject corals to damage, different from porous polyethylene orbital implants. Porous implants show the best prosthesis motility and a minimum rate of implants extrusion. Implant wraps can facilitate smoother entry of the implant into the orbit and allow reattachment of extraocular muscles. They also serve as a barrier between the overlying soft tissue and the rough surface of the implant, protecting implants from exposure or erosion.

Influence of Ridge Inclination and Implant Localization on the Association of Mandibular Kennedy Class I Removable Partial Denture

The aim of this study was to evaluate the tendency of displacement of the supporting structures of the distal extension removable partial denture (DERPD) associated to the implant with different inclinations of alveolar ridge and implant localizations through a two-dimensional finite-element method. Sixteen mandibular models were fabricated, presenting horizontal, distally descending, distally ascending, or descending-ascending ridges. All models presented the left canine and were rehabilitated with conventional DERPD or implant-retained prosthesis with the ERA system. The models were obtained by the AutoCAD software and transferred to the finite-element software ANSYS 9.0 for analysis. A force of 50 N was applied on the cusp tips of the teeth, with 5 points of loading of 10 N. The results were visualized by displacement maps. For all ridge inclinations, the assembly of the DERPD with distal plate retained by an anterior implant exhibited the lowest requisition of the supporting structures. The highest tendency of displacement occurred in the model with distally ascending ridge with incisal rest. It was concluded that the association of the implant decreased the displacement of the DERPD, and the anterior positioning of the implant associated to the DERPD with the distal plate preserved the supporting structures for all ridges.

Retention Systems to Implant-Supported Craniofacial Prostheses

Osseointegrated implants in craniofacial reconstructions improve prostheses retention and stability and comfort and safety for a patient. According to biomechanical principles, the treatment success regarding osseointegration maintenance depends on an adequate surgical technique associated to a retention system that provides favorable tension distribution to implants. Furthermore, patient expectation, esthetics, function, and anatomic limitations must be evaluated during treatment planning. Therefore, the aims of this study were to present available retention systems to implant-supported craniofacial prosthesis and to highlight the advantages, indications, and limitations. A literature review was conducted through a MEDLINE search. Sixteen articles and 2 textbooks met the inclusion criteria and were included in the review. It was concluded that the success of craniofacial rehabilitation with implants depends on an adequate surgical technique and an adequate selection of a retention system.

Photoelastic Stress Analysis of Different Attachment Systems on Implant-Retained and Conventional Palatal Obturator Prostheses

Background: Considering that an increasing number of patients are victims of mutilator surgical resections, these studies are important for treatment success of rehabilitation of patients presenting oronasal communication.Purpose: The aim of this study was to assess the stress distribution through photoelasticity in palatal obturator prostheses with different attachment systems for implants.Methods: Two photoelastic models were obtained from an experimental maxillary model presenting an oronasal communication. One model was fabricated without implant, and the other with 2 implants 10 mm in length inserted in the left crest. Four colorless palatal obturator prostheses were fabricated. One prosthesis presented no attachment system, whereas the remaining prostheses were adapted to 3 attachment systems. The assembly was positioned in a circular polariscope for application of axial load.Results: The results were based on photographic records of stress in the photoelastic model submitted to loading. The records revealed higher stress concentration on the bar-clip system followed by the O'ring/bar-clip and O'ring systems, respectively. A homogeneous stress distribution was observed on the photoelastic model with the mucous-supported prosthesis.Conclusions: The attachment systems generated different characteristics of stress distribution that was concentrated surrounding the implants. The bar-clip system exhibited the highest stress concentration on the alveolar crest.

Prevalence of removable partial dentures users treated at the Aracatuba Dental School - UNESP

Objectives: The aim of this study was to evaluate the frequency of removable partial dentures (RPD) at the Aracatuba Dental School.Methods: The study was conducted by analysing 412 clinical history of patients attended at the RPD clinics in the period from 2000 to 2007.Results: 412 charts were analysed: 148 (35.9%) men and 264 (64.1%) women. The mean age was 53.8 years (men) and 52.4 years (women). A total of 556 dentures were made; of these, 233 (41.90%) were maxillary and 323 (58.09%) were mandibular dentures. The most frequent Kennedy classification found was Class III (maxilla) and Class I (mandible). In the maxilla, 55% (126) of the major connectors were of the anterior-posterior palatal bar, while in the mandible, 64% (202) were the lingual bar. As regards the claps, 401 were circumferential and 318 were bar claps.Conclusion: The mean age of the patients was 52.9 years with higher prevalence of female patients; the most frequent Kennedy's classification was Class I in mandible and Class III in maxilla; the most common major connector was anterior-posterior palatal bar for maxilla and lingual bar for mandible; the circumferential clasps were the most common retainer used in both jaws.

Three-Dimensional Finite Element Analysis of Vertical and Angular Misfit in Implant-Supported Fixed Prostheses

Purpose: Three-dimensional finite element analysis was used to evaluate the effect of vertical and angular misfit in three-piece implant-supported screw-retained fixed prostheses on the biomechanical response in the peri-implant bone, implants, and prosthetic components. Materials and Methods: Four three-dimensional models were fabricated to represent a right posterior mandibular section with one implant in the region of the second premolar (2PM) and another in the region of the second molar (2M). The implants were splinted by a three-piece implant-supported metal-ceramic prosthesis and differed according to the type of misfit, as represented by four different models: Control = prosthesis with complete fit to the implants; UAM (unilateral angular misfit) = prosthesis presenting unilateral angular misfit of 100 pm in the mesial region of the 2M; UVM (unilateral vertical misfit) = prosthesis presenting unilateral vertical misfit of 100 pm in the mesial region of the 2M; and TVM (total vertical misfit) = prosthesis presenting total vertical misfit of 100 pm in the platform of the framework in the 2M. A vertical load of 400 N was distributed and applied on 12 centric points by the software Ansys, ie, a vertical load of 150 N was applied to each molar in the prosthesis and a vertical load of 100 N was applied at the 2PM. Results: The stress values and distribution in peri-implant bone tissue were similar for all groups. The models with misfit exhibited different distribution patterns and increased stress magnitude in comparison to the control. The highest stress values in group UAM were observed in the implant body and retention screw. The groups UVM and TVM exhibited high stress values in the platform of the framework and the implant hexagon, respectively. Conclusions: The three types of misfit influenced the magnitude and distribution of stresses. The influence of misfit on peri-implant bone tissue was modest. Each type of misfit increased the stress values in different regions of the system. INT J ORAL MAXILLOFAC IMPLANTS 2011;26:788-796

Most Frequent Tumors in Maxillofacial Area Rehabilitated Through Surgical Reconstruction and Prostheses

Cancer is regarded as the abnormal cellular multiplication; it is not controlled by the organism; and its cells present a differentiated DNA. Initially, the disease does not show clinical signs, but it can be diagnosed by laboratorial examinations. When tumors are present in the maxillofacial area, they can entail the loss of these area organs, which become responsible for the carrier's social environment exclusion. This paper aimed at showing, through a literature review, the cancers that more commonly happen in the face and the possibilities of regenerating in the patient mutilated through surgical reconstruction and prostheses.

Influence of Implant Inclination Associated With Mandibular Class I Removable Partial Denture

The aim of this study was to use two-dimensional finite element method to evaluate the displacement and stress distribution transmitted by a distal extension removable partial denture (DERPD) associated with an implant placed at different inclinations (0, 5, 15, and 30 degrees) in the second molar region of the edentulous mandible ridge. Six hemimandibular models were created: model A, only with the presence of the natural tooth 33; model B, similar to model A, with the presence of a conventional DERPD replacing the missing teeth; model C, similar to the previous model, with a straight implant (0 degrees) in the distal region of the ridge, under the denture base; model D, similar to model C, with the implant angled at 5 degrees in the mesial direction; model E, similar to model C, with the implant angled at 15 degrees in the mesial direction; and model F, similar to ME, with the implant angled at 30 degrees in the mesial direction. The models were created with the use of the AutoCAD 2000 program (Autodesk, Inc, San Rafael, CA) and processed for finite element analysis by the ANSYS 8.0 program (Swanson Analysis Systems, Houston, PA). The force applied was vertical of 50 N on each cusp tip. The results showed that the introduction of the RPD overloaded the supporting structures of the RPD and that the introduction of the implant helped to relieve the stresses of the mucosa alveolar, cortical bone, and trabecular bone. The best stress distribution occurred in model D with the implant angled at 5 degrees. The use of an implant as a support decreased the displacement of alveolar mucosa for all inclinations simulated. The stress distribution transmitted by the DERPD to the supporting structures was improved by the use of straight or slightly inclined implants. According to the displacement analysis and von Mises stress, it could be expected that straight or slightly inclined implants do not represent biomechanical risks to use.

Evaluation of Bone Insertion Level of Support Teeth in Class I Mandibular Removable Partial Denture Associated With an Osseointegrated Implant: A Study Using Finite Element Analysis

Purpose: This study evaluated the influence of distal extension removable partial denture associated with implant in cases of different bone level of abutment tooth, using 2D finite element analysis.Materials and Methods: Eight hemiarch models were simulated: model A-presenting tooth 33 and distal extension removable partial denture replacing others teeth, using distal rest connection and no bone lost; model B-similar to model A but presenting distal guide plate connection; model C-similar to model A but presenting osseointegrated implant with ERA retention system associated under prosthetic base; model D-similar to model B but presenting osseointegrated implant as described in model C; models E, F, G, and H were similar to models A, B, C, and D but presenting reduced periodontal support around tooth 33. Using ANSYS 9.0 software, the models were loaded vertically with 50 N on each cusp tip. For results, von Mises Stress Maps were plotted.Results: Maximum stress value was encountered in model G (201.023 MPa). Stress distribution was concentrated on implant and retention system. The implant/removable partial denture association decreases stress levels on alveolar mucosa for all models.Conclusions: Use of implant and ERA system decreased stress concentrations on supporting structures in all models. Use of distal guide plate decreased stress levels on abutment tooth and cortical and trabecular bone. Tooth apex of models with reduced periodontal support presented increased stress when using distal rest. (Implant Dent 2011;20:192-201)

Care and Cleaning of Maxillofacial Prostheses

Both the cleaning and care of the prosthesis are fundamental for maintaining its quality. Therefore, the aim of this study was to show the methods of cleaning and care the patient needs to take as regards the prosthesis and adjacent tissue, starting with correct instruction and training by the professional. It has been verified that among the materials for fabricating maxillofacial prostheses, silicone was considered the major retainer of microorganisms on its surface. Therefore, for cleaning prostheses, the use of water and neutral soap, as well as chlorhexidine, is recommended. As regards care of the adjacent tissues, it is recommended to remove the prosthesis before going to sleep, in addition to washing the prosthesis receptor tissues with water and neutral soap or with a mixture of hydrogen peroxide and water. Whereas for the mucosal surfaces of the ophthalmic cavity, cleaning with filtered and boiled water or physiological solution at least 3 times a day is recommended.