Effect of Fabrication Technique on the Microgap of CAD/CAM Cobalt-Chrome and Zirconia Abutments on a Conical Connection Implant: An In Vitro Study.

The aim of this in vitro study was to investigate the microgaps at the implant-abutment interface when zirconia (Zr) and CAD/CAM or cast Co-Cr abutments were used. METHODS: Sixty-four conical connection implants and their abutments were divided into four groups (Co-Cr (milled, laser-sintered and castable) and Zirconia (milled)). After chewing simulation (300,000 cycles, under 200 N loads at 2 Hz at a 30° angle) and thermocycling (10,000 cycles, 5 to 50 °C, dwelling time 55 s), the implant-abutment microgap was measured 14 times at each of the four anatomical aspects on each specimen by using a scanning electron microscope (SEM). Kruskal-Wallis and pair-wise comparison were used to analyze the data (α = 0.05). RESULTS: The SEM analysis revealed smaller microgaps with Co-Cr milled abutments (0.69-8.39 µm) followed by Zr abutments (0.12-6.57 µm), Co-Cr sintered (7.31-25.7 µm) and cast Co-Cr (1.68-85.97 µm). Statistically significant differences were found between milled and cast Co-Cr, milled and laser-sintered Co-Cr, and between Zr and cast and laser-sintered Co-Cr (p < 0.05). CONCLUSIONS: The material and the abutment fabrication technique affected the implant-abutment microgap magnitude. The Zr and the milled Co-Cr presented smaller microgaps. Although the CAD/CAM abutments presented the most favorable values, all tested groups had microgaps within a range of 10 to 150 µm.

Biocompatibility and Effectiveness of a Novel, Organic Olive Oil-Based Denture Adhesive: A Multicenter Randomized and Placebo-Controlled Clinical Trial.

To assess the clinical efficacy of a novel, organic olive oil-based denture adhesive and its effect on Candida albicans growth in maxillary edentulous individuals wearing complete dentures, individuals were selected from two dental schools in Portugal and Spain. Twenty-eight complete dentures were relined, following a standardized protocol. The novel product (test) was compared with a commercialized adhesive (control) and Vaseline (placebo) randomly assigned in a cross-study design. The retention resistance was measured with a gnathometer and a dynamometer. The patients related outcome evaluations with a five-point questionnaire, and the Candida albicans growth in a Sabouraud dextrose agar (SDA) medium was used to evaluate differences between the placebo and experimental product. Twenty-three participants were included. The dynamometer evaluation showed significant differences between not using a denture adhesive and using either (experimental, p = 0.03; control, p = 0.04) and no significant differences between the two adhesives (p > 0.05). In the subjective analysis, the experimental adhesive showed a significantly longer effectiveness (p = 0.001), and the control reported better results in taste (p = 0.03) and in chewing (p = 0.001). The test adhesive showed better (p < 0.001) Candida albicans growth inhibition. The experimental adhesive showed longer effectiveness than the control and the placebo with a better inhibition capacity for the growth of Candida albicans. Patients reported better abilities for speech, chewing, taste, and retirement in the control adhesive.

Comparative In Vitro Study of the Bond Strength of Composite to Carbon Fiber Versus Ceramic to Cobalt-Chromium Alloys Frameworks for Fixed Dental Prostheses.

PURPOSE: The aim of this comparative in vitro study was to assess the bond strength and mechanical failure of carbon-fiber-reinforced composites against cobalt-chrome structures with ceramic veneering. MATERIALS AND METHODS: A total of 24 specimens (12 per group) simulating dental prosthetic frameworks were fabricated. The experimental specimens were subjected to a thermocycling aging process and to evaluate bond strength. All specimens were subjected to a three-point bending test to fracture using a universal testing machine. RESULTS: The cobalt-chrome/ceramic group yielded a bond strength value of 21.71 ± 2.16 MPa, while the carbon-fiber-reinforced composite group showed 14.50 ± 3.50 MPa. The failure assessment reported statistical significance between groups. Although carbon-fiber-reinforced composite group showed lower bond strength values, the chipping incidence in this group was as well lower. CONCLUSIONS: The chrome-cobalt/ceramic group showed greater bonding strength compared to the carbon-fiber-reinforced composite; most of the fractures within the cobalt-chrome/ceramic group, had no possibility of direct clinical repair.

Evaluation of the clinical behavior of 2 different materials for implant-supported interim fixed partial prostheses: A randomized clinical trial.

STATEMENT OF PROBLEM: Clinical studies about interim implant-supported prostheses made of polymethylmethacrylate (PMMA) and polyoxymethylene (POM) have been limited to clinical reports or studies on the survival of implants subjected to immediate loading without evaluating the influence of the material used. PURPOSE: The purpose of this randomized clinical trial was to evaluate the clinical performance of posterior resin interim implant-supported fixed partial dentures (FPDs) made of 2 different computer-aided design and computer-aided manufactured (CAD-CAM) materials: PMMA and POM. MATERIAL AND METHODS: A total of 21 participants received 49 interim implant-supported FPDs. The same participant received the PMMA as part of the control group and the POM as part of the experimental group. The restorations were evaluated at 1 week and 3 and 6 months after their placement, using the California Dental Association (CDA) quality-evaluation index. Their functional wear and color stability were also evaluated. Data were analyzed by using nonparametric statistics (α=.05). RESULTS: The CDA criteria showed that the PMMA group performed better than the POM group in the surface and color parameter (P<.05). Fractures at the implant connection level were observed in 10 prostheses. The number of fractures was significantly higher in internal conical connection implants (P<.05). The statistical analysis of color stability showed values of ΔE*ab of 7.18 for PMMA and 8.58 for POM, without significant differences between materials. Concerning the wear evaluation, a significant increase in the wear of both materials was found at 6 months of functioning (P<.05). No significant differences were found within materials. CONCLUSIONS: Within a 6-month observation period, PMMA interim implant-supported FPDs performed better than POM in the surface and color parameter. Entirely polymer posterior implant-supported FPDs with internal conical connection implants appear to be more susceptible to fracture.

Improving PMMA resin using graphene oxide for a definitive prosthodontic rehabilitation - A clinical report.

The use of acrylic resins as a definitive material has shown some advantages comparing to other definitive materials. However, their poor mechanical properties remain a major drawback. In this case report, graphene oxide (GO) was incorporated into polymethyl methacrylate (PMMA) resin for a definitive maxillary rehabilitation, combined with an intraoral digital impression and a three-dimensional facial scan. After 8 months of the placement of the definitive prosthesis, no mechanical, aesthetic, or biologic complications were reported, and the soft tissues showed excellent health and stability. The incorporation of GO in PMMA resins seems to be a suitable option for prosthetic rehabilitation. However, further studies are needed to ensure rigorous scientific support of these techniques and materials. Key words:Computer-aided design, computer-aided manufacturing, dental impression technique, dental prosthesis; graphene oxide.

Polylactic Acid as a Material for Three-Dimensional Printing of Provisional Restorations.

PURPOSE: To assess the marginal fit of provisional polylactic acid (PLA) crowns obtained via three-dimensional (3D) printing using a profile projector. MATERIALS AND METHODS: A stone cast was scanned, and 15 provisional dental crowns were designed and printed in PLA using a 0.2-mm nozzle and 135-degree build angle. The marginal fit was measured at six points on each crown using a profile projector. RESULTS AND CONCLUSION: Within the limitations of this study, the marginal fit of PLA provisional restorations was clinically acceptable, and the results were comparable to those observed with polymethyl methacrylate provisional restorations.

Factors Affecting the Decision to Use Cemented or Screw-Retained Fixed Implant-Supported Prostheses: A Critical Review.

PURPOSE: This review aimed to compile and enumerate all the factors described in the literature that may affect the decision to use either cemented or screw-retained restorations and to determine the relative weights of each factor by type of retention and prosthesis. MATERIALS AND METHODS: The literature was reviewed, and the factors were classified as either determining (present in a clinical situation in which one of the retention mechanisms was clearly more suitable than the other) or conditioning (present in clinical situations in which one type of restoration was not clearly more advantageous than the other). RESULTS: Three determining factors (esthetic outcome, retention, and biologic risk) and five conditioning factors (passive fit, fracture strength, occlusal area, complications, and retrievability) were identified. CONCLUSION: Although there is not a clearly better alternative for all clinical situations, determining factors in certain scenarios can render one of the two approaches more recommendable. For esthetic reasons, when the implant angle cannot be corrected to conceal the access hole, cementation is more suitable; however, screw retention is the better option when the occlusal space is under 6 mm or margins cannot be located supra- or equigingivally. In the absence of determining factors, the decision should be based on conditioning factors, which carry different weights depending on the type of prosthesis.

Biologically oriented preparation technique (BOPT) for implant-supported fixed prostheses.

A patient of 58 years of age without medical problems came to the clinic due to missing teeth in the upper posterior region and to change the partial fixed prosthesis in the upper anterior area. Proposed treatment: surgical phase of three conical shape tapering implants with prosthetic platform in occlusal direction with mechanize collar tissue level with fixtures to place implant-supported metal-ceramic restorations. In the anterior area, a zirconium oxide fixed partial prosthesis was vertical preparation of the tooth's. When preparing teeth to receive fixed prostheses, the definition and shape of finish lines has been a subject of endless discussion, modification, and change ever since the beginnings of restorative prosthetic dentistry. The BOPT technique (biologically oriented preparation technique) was first described in the context of tooth-supported restorations but has recently been applied to dental implants with the aim of ensuring healthy peri-implant tissue and creating the possibility of modeling the peri-implant sulcus by modifying prosthetic emergence profiles. Vertical preparation of teeth and abutments without finish line on implants is a technique which was found to be adequate for ensuring the remodeling and stability of peri-implant tissues. Key words:Peri-implant tissue health, shoulderless abutments.

CAD/CAM Conic Crowns for Predictable Retention in Implant-Supported Prostheses.

PURPOSE: To evaluate CAD/CAM conic crowns to obtain a reversible and predictable retention in implant-supported prostheses. MATERIALS AND METHODS: Five 1- to 8-degree CAD/CAM abutments and their respective copings (n = 40) were designed and manufactured to measure the retention strength (in N) on a Zwick/Roell testing frame. RESULTS: The mean retention strength values found, in descending order of cone angle, were as follows: 8 degrees, 21.02 N; 7 degrees, 23.16 N, 28 N, and 36.40 N; 6 degrees, 40.46 N; 5 degrees, 66.36 N; 4 degrees, 61.23 and 76.12 N; 3 degrees, 93.44 N, 103.21 N, and 112.04 N; 2 degrees, 154.20 N; and 1 degree, 204.74 N, 261 N, and 293.40 N. These data describe a high-intensity ratio with a curvilinear trend that can be used to develop predictive models. CONCLUSION: With the limits of this study, it can be concluded that retention strength increased as the cone angle decreased. The data described a curve from which two predictive models were developed to find retention strength from the cone angle used and the cone angle that would be needed to deliver a given retention strength. This study is the first step in searching for an alternative to cemented and screw-retained implant-supported prostheses and new retaining elements in implant-retained prostheses.

The Effect of Compressive Cyclic Loading on the Retention of Cast Single Crowns Cemented to Implant Abutments.

PURPOSE: The aim of this study was to evaluate and compare the retention strength of three cements commonly used in implant-supported prostheses before and after compressive cyclic loading. MATERIALS AND METHODS: The working model consisted of five solid abutments, 7 mm in height and with a 6-degree taper, screw retained to five implant analogs secured in a rectangular block of self-curing acrylic. On the abutments, 30 metal Cr-Ni alloy copings were cemented using three luting agents: glass ionomer, resin urethane-based, and compomer cement (n = 10). Two tensile tests were conducted with a universal testing machine, before and after 100,000 cycles of 100 N and 0.72 Hz compressive cyclic loading in a humid environment. RESULTS: Before applying the compressive load, the retention strength of the resin urethane-based cement was slightly higher than that of the compomer cement and 75% greater than the glass-ionomer cement. After compressive loading, the resin urethane-based cement showed the highest percentage of loss of retention (64.45%, compared with 50% for glass-ionomer and compomer cement). However, the glass-ionomer cement showed the lowest mean retentive strength with 50.35 N as opposed to 75.12 N for the compomer cement and 71.25 N for the resin urethane-based. CONCLUSIONS: Compressive cyclic loading significantly influences the retention strength of the luting agents tested. All three cements may favor the retrievability of the crowns.

Influence of orthodontic treatment on temporomandibular disorders. A systematic review.

OBJECTIVES: The aim of this literature systematic review was to evaluate the possible association between malocclusions, orthodontic treatment and development of temporomandibular disorders. MATERIAL AND METHODS: A search was carried out on PubMed-Medline database from January 2000 to August 2013 using the keywords "orthodontics and temporomandibular disorders", "orthodontics and facial pain" and "malocclusion and temporomandibular disorders". Human studies included in the study were those assessing signs and symptoms of temporomandibular disorders in relation to orthodontic treatment. MATERIAL AND METHODS: A search was carried out on PubMed-Medline database from January 2000 to August 2013 using the keywords "orthodontics and temporomandibular disorders", "orthodontics and facial pain" and "malocclusion and temporomandibular disorders". Human studies included in the study were those assessing signs and symptoms of temporomandibular disorders in relation to orthodontic treatment. RESULTS: The search strategy resulted in 61 articles. After selection according to the inclusion/exclusion criteria 9 articles qualified for the final analysis. The articles which linked orthodontics and development of temporomandibular disorders showed very discrepant results. Some indicated that orthodontic treatment could improve signs and symptoms of temporomandibular disorders, but none of them obtained statistically significant differences. CONCLUSIONS: According to the authors examined, there is no evidence for a cause-effect relationship between orthodontic treatment and temporomandibular disorders, or that such treatment might improve or prevent them. More longitudinal studies are needed to verify any possible interrelationship. Key words:Malocclusion and temporomandibular disorders, orthodontics and facial pain, orthodontics and temporomandibular disorders, temporomandibular disorders, temporomandibular dysfunction.

Influence of Articulating Paper Thickness on Occlusal Contacts Registration: A Preliminary Report.

The objective of this preliminary study was to determine if the occlusal contact surface registered with an articulating paper during fixed prosthodontic treatment was contained within the area marked on a thicker articulating paper. This information would optimize any necessary occlusal adjustment of a prosthesis' veneering material. A convenience sample of 15 patients who were being treated with an implant-supported fixed singleunit dental prosthesis was selected. Occlusal registrations were obtained from each patient using 12-µm, 40-µm, 80-µm, and 200-µm articulating paper. Photographs of the occlusal registrations were obtained, and pixel measurements of the surfaces were taken and overlapped for comparison. The results showed that the thicker the articulating paper, the larger the occlusal contact area obtained. The differences were statistically significant. In all cases, the occlusal registrations obtained with the thinnest articulating paper were contained within the area marked on the thickest articulating paper. The results suggested that the use of thin articulating papers (12-µm or 40-µm) can avoid unnecessary grinding of veneering material or teeth during occlusal adjustment.

Bonding metals to poly(methyl methacrylate) using aryldiazonium salts.

OBJECTIVES: Many dental devices, such as partial dentures, combine acrylic and metallic parts that are bonded together. These devices often present catastrophic mechanical failures due to weak bonding between their acrylic and metallic components. The bonding between alloys and polymers (e.g. poly(methyl methacrylate), PMMA) usually is just a mechanical interlock, since they do not chemically bond spontaneously. The aim of this study was to develop a new method to make a strong chemical bond between alloys and polymers for dental prostheses based on diazonium chemistry. METHODS: The method was based on two steps. In the first step (primer), aryldiazonium salts were grafted onto the metallic surfaces. The second step (adhesive) was optimized to achieve covalent binding between the grafted layer and PMMA. The chemical composition of the treated surfaces was analyzed with X-ray photoelectron spectroscopy (XPS), and the tensile or shear bonding strength between metals and poly(methyl methacrylate) was measured. RESULTS: XPS and contact angle measurements confirmed the presence of a polymer coating on the treated metallic surfaces. Mechanical tests showed a significant increase in bond strength between PMMA and treated titanium or stainless steel wire by 5.2 and 2.5 folds, respectively, compared to the untreated control group (p<0.05). SIGNIFICANCE: Diazonium chemistry is an effective technique for achieving a strong chemical bond between alloys and PMMA, which can help improve the mechanical properties of dental devices.

Dental profile of a community of recovering drug addicts: Biomedical aspects. Retrospective cohort study.

OBJECTIVES: to obtain a biomedical oral profile of a community of adult drug addicts in treatment by analysing their dental health, with a view to determining whether the state of their oral health could be attributed primarily to their lifestyle and the direct consequences of drug abuse on their overall condition, rather than to the effects of the drugs used. EXPERIMENTAL DESIGN: The study was conducted under the terms of an agreement between the Complutense University of Madrid's (UCM) Odontology Faculty and the City of Madrid's Substance Abuse Institute. Seventy drug addicts and 34 control group subjects were examined. The study assessed oral hygiene habits, systemic pathology, type of drugs used and the duration of use, oral pathology, oral health indices, risk of caries based on saliva tests, oral candidiasis and periodontal microbiology. RESULTS: Statistically significant differences (p<0.05) were found between the test and control groups for practically all the variables analysed. In the drug users group, dental hygiene was wanting, systemic and oral pathology prevailed and the decayed/missing/filled teeth or surface (DMFT/S) indices denoted very poor buccodental health. The saliva tests showed a substantial risk of caries and candidiasis rates were high. By contrast, with a single exception, the microbiological studies detected no statistically significant difference between drug users and control groups periodontal flora. CONCLUSIONS: Drug-dependent patients had poor oral health and a significant increase in oral pathology, essentially caries and periodontal disease. Their risk of caries was high and the presence of candidiasis was representative of their poor general and oral health. Drug users' poor buccodental condition was more closely related to lifestyle than to drug abuse itself.

Protocolo actual en la terapia de la periimplantitis / Current protocol in periimplatitis therapy

La periimplantitis es un proceso patológico inflamatorio de los tejidos que rodean al implante que cursa con una pérdida ósea progresiva e irreversible. El objetivo del tratamiento de la periimplantitis es conseguir la eliminación de la infección bacteriana, una reducción de la profundidad de la bolsa y una ausencia de sangrado al sondaje; así como prevenir la pérdida de tejidos de soporte mediante una terapia de apoyo adecuada. En los procedimientos profesionales para el control de la infección se incluye la retirada de los depósitos bacterianos de los componentes del implante y la supraestructura. Sin embargo, en ocasiones hay que recurrir a terapia quirúrgica, que consiste en crear el acceso para la limpieza y descontaminación de la superficie del implante (AU)

Peri-implantitis is an inflammatory disease of the tissues surrounding the implant that leads to a progressive and irreversible bone loss. The treatment for peri-implantitis aims to achieve the elimination of bacterial infection, a reduction in the depth of the bag and an absence of bleeding on probing, as well as preventing the loss of support tissues by means of an appropriate support therapy. Professional procedures for infection control include the removal of bacterial deposits from the components of the implant and the superstructure. However, there is sometimes a need to resort to surgical therapy, which consists of creating access for cleaning and decontaminating the surface of the implant (AU)

Medidas de inclinación de la trayectoria condílea y delángulo de bennet de lapoblación occidental, actualización y revisió nbibliográfica / Condylar path inclination and bennet angle in western population, update and literature review

Introducción: Actualmente cualquier tratamiento prostodóncico conlleva el uso de articuladores tanto para el diagnóstico como la realización de las prótesis. Aunque lo ideal sería individualizar cada caso hallando la inclinación de la trayectoria con dílea (ITC)y el ángulo de Bennet reales, se tiende a trabajar con los valores estándares establecidos. Dichos valores llevan vigentes desde que fueron instaurados sin ninguna modificación. El objetivo de este estudio fue comprobar que estos valores promedios seguían siendo validos en la actualidad. Material y método: Recopilación de valores reales de ITC y ángulo de Bennet recogidos de la bibliografía entre 1959 y 2011. Fueron seleccionados 34 estudios de grandes muestras poblacionales alcanzando un total de 2.142 valores individualizados de ITC. Resultados: Fueron encontradas grandes diferencias entre los distintos estudios revisados, desde valores medios de ITC de30,1º en 1960 hasta los 57,8º de 2009.Conclusiones: Se observó un incremento gradual de las medias de ITC a lo largo de los años, derivado por una masticación con predominio de los movimientos verticales de apertura-cierre frente a lateralidades. Estos resultados se alejan de los propuestos para los articuladores de guías fijas que son los más empleados en laboratorio. Consideramos que dichos valores estándares deben ser modificados con unas cifras mayores (AU)

Introduction: Currently any prosthodontic treatment involves the use of articulators for diagnosis and prostheses fabrication. The ideal protocol would be to individualizing each case getting the actual condylar path inclination (CPI) and Bennet angle. Although dentists used to work with the stablished standard values. Predeterminated articulator settings have been the same since they were instituted without any change. The aim of this study was to verify that these average values were still valid today. Material and methods: Collection of real CPI and Bennet angle values review from the literature between 1959 and 2011. Thirty four studies were selected from large population samples for a total of 2142 individual condylar values. Results: Large differences between the studies reviewed were found, from average values CPI of 30.1 degrees in 1960 to 57.8 º, 2009.Conclusions: It was observed a gradual increase in average CPI over the years, which indicates vertical chewing movements over lateral ones. These results are far from those proposed for semi-adjustable articulators. Therefore, these standard values must be reinstated with higher figures rather than relying on overage values (AU)

In vitro study of the adherence of Candida albicans to acrylic resins: relationship to surface energy.

PURPOSE: This study aimed to determine whether small variations in the composition of the polymethylmethacrylate (PMMA) of widely used dentures produce differences in the degree of Candida albicans adherence and to relate any differences found to the surface energy of the resins, which appears to play a major role in the initial phases of microorganism adhesion. MATERIALS AND METHODS: A reference strain of C albicans (18.804 ATCC) and 11 different PMMAs (Vacalon, Inkotherm 85, Veracril, Probase Cold, Inkotherm Press, Inkotherm 85 T, Ruthinium, Vertex, SR Ivocap, Idoacryl, Lucitone) were used. Fifty specimens (15 x 10 x 1 mm) of each type were prepared. C albicans adhesion was determined by microorganism count under fluorescent optical microscope, and the surface energy of the resins was calculated by the contact angle method. P < .05 was regarded as significant. RESULTS: C albicans adhesion on the resins ranged from 7.12 cells/mm2 to 330.8 cells/mm2, with statistically significant (P > .05) differences in some cases. Despite small variations in the composition of the resins, their surface energy values were very similar (38.78 to 41.2 mJ/m2), and no relationship was found between C albicans adhesion and surface energy. CONCLUSION: The adhesion of C albicans to different resins varied in vitro, possibly as a result of the action of residual postpolymerization products. According to these results, variations in surface energy that result from differences in the composition of the different PMMA resins appear to have no influence on the adhesion of C albicans or, therefore, on the onset of denture stomatitis.