Ultraviolet C as a method of disinfecting medical silicone used in facial prostheses: An in vitro study - Part 2.

STATEMENT OF PROBLEM: Disinfection is an important factor in preserving facial prostheses and maintaining tissue health. However, whether disinfection with ultraviolet C is an effective disinfection method is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effectiveness of irradiation with different exposure durations of an ultraviolet-C light-emitting diode in the disinfection of the silicone (A-588-1; Factor II) used in facial prostheses. MATERIAL AND METHODS: A total of 216 specimens were prepared, contaminated by multispecies biofilm, and divided into 9 groups (n=24) for different treatments: chlorhexidine 0.12% (G CHG), ultraviolet-C light-emitting diode for 5 minutes (G UVC5), ultraviolet-C light-emitting diode for 10 minutes (G UVC10), ultraviolet-C light-emitting diode for 20 minutes (G UVC20), their respective untreated controls (Gcontrol CHG, Gcontrol UVC5, Gcontrol UVC10, Gcontrol UVC20), and dimethyl sulfoxide (G DMSO) as the negative control. Cell viability was measured by using the methyl tetrazolium salt (MTT) method. Two statistical analyses were performed. First, a 2×3 ANOVA was carried out to compare the control groups (Gcontrol UVC5, Gcontrol UVC10, and Gcontrol UVC20) and the experimental groups of UV-C LED light with different exposure durations (G UVC5, G UVC10, and G UVC20). The second analysis was performed using generalized linear models to compare the optical density of the groups (G UVC5, G UVC10, G UVC20, G CHG, and G DMSO). RESULTS: Cell viability results demonstrated a microbial reduction after exposure to the ultraviolet-C light-emitting diode for 20 minutes (G UVC20) compared with untreated controls (P<.05). The 5- and 10-minute exposures were statistically similar to their respective control groups (P>.05). The 20 minutes exposure had the lowest average optical density value, being statistically different from the 5-minute exposure (P<.05). A 20-minute exposure to the ultraviolet-C light-emitting diode (G UVC20) was similarly effective when compared with the standard disinfection treatment (G CHG) and dimethyl sulfoxide (G DMSO) (P>.05). CONCLUSIONS: Irradiation with an ultraviolet-C light-emitting diode for 20 minutes decreased the in vitro microbial cell viability on the medical silicone used in facial prostheses.

Influence of Restorative Material on the Distribution of Loads to the Bone in Hybrid Abutment Crowns-In Vitro Study.

Background: The objective of this study was to evaluate the load transmitted to the peri-implant bone by seven different restorative materials in single-unit rehabilitations with morse taper implants using a strain gauge. Materials: In a polyurethane block that simulated type III bone, a morse taper platform implant was installed (3.5 × 11 mm) in the center and 1 mm below the test base surface, and four strain gauges were installed around the implant, simulating the mesial, distal, buccal and lingual positions. Seven similar hybrid abutment crowns were crafted to simulate a lower premolar using different materials: 1-PMMA; 2-glass ceramic over resin matrix; 3-PEEK + lithium disilicate; 4-metal-ceramic; 5-lithium disilicate; 6-zirconia + feldspathic; 7-monolithic zirconia. All groups underwent axial and oblique loads (45 degrees) of 150 N from a universal testing machine. Five measurements (n = 5) were performed with each material and for each load type; the microdeformation data underwent statistical analysis. The data were obtained in microdeformation (µÎµ), and the significance level was set at p ≤ 0.05. Results: There was no statistically significant difference in the evaluation among the materials under either the axial load or the oblique load at 45 degrees. In turn, in the comparison between axial load and oblique load, there was a difference in load for all materials. Conclusion: The restorative material did not influence the load transmitted to the bone. Furthermore, the load transmitted to the bone was greater when it occurred obliquely at 45° regardless of the material used. In conclusion, it appeared that the different elastic modulus of each material did not influence the load transmission to the peri-implant bone.

Interaction of different concentrations of 10-MDP and GPDM on the zirconia bonding.

OBJECTIVES: To analyze the influence of different concentrations of 10-MDP and GPDM used, combined or not, on the bonding to zirconia. METHODS: Specimens of zirconia and a resin-composite (7 mm length, 1 mm width, and 1 mm thick) were obtained. The experimental groups were obtained according to the functional monomer (10-MDP and GPDM) and the concentrations (3 %, 5 %, and 8 %). For the groups with combined 10-MDP and GPDM, the agents were used with a proportion of 50 %/50 % wt until reaching the 3 %, 5 % and 8 % concentrations. All monomers were diluted in ethanol to obtain the primers. Two control groups were established: ethanol (negative control) and a commercial reference Monobond N (positive control). The zirconia surface treatment was performed with the primer application followed by the bonding to a resin-composite sample with a light-curing resin cement. Twenty-four hours after the adhesive procedure, a microtensile test was performed and the failure pattern of each sample was analysed with a stereoscopic magnifying glass. Data were analysed by a two-way ANOVA and Dunnet test. RESULTS: All experimental primers presented a higher bond strength than the negative control (ethanol). Excepting the 8 % GPDM primer, all groups presented statistically similar bond strength compared to the positive control, with a predominance of adhesive failure. SIGNIFICANCE: 10-MDP, GPDM, and the combination of both for the concentrations tested promote an effective chemical bonding to zirconia. However, using 10-MDP and GPDM in the same primer has no synergistic effect.

Marginal Bone Level and Biomechanical Behavior of Titanium-Indexed Abutment Base of Conical Connection Used for Single Ceramic Crowns on Morse-Taper Implant: A Clinical Retrospective Study.

The goal of this retrospective clinical study was to evaluate the behavior of Morse-taper indexed abutments by analyzing the marginal bone level (MBL) after at least 12 months of function. Patients rehabilitated with single ceramic crowns between May 2015 and December 2020 received single Morse-taper connection implants (DuoCone implant) with two-piece straight abutment baseT used for at least 12 months, presenting periapical radiograph immediately after crown installation were enrolled. The position of the rehabilitated tooth and arch (maxilla or mandible), crown installation period, implant dimensions, abutment transmucosal height, installation site (immediate implant placement or healed area), associated with bone regeneration, immediate provisionalization, and complications after installation of the final crown were analyzed. The initial and final MBL was evaluated by comparing the initial and final X-rays. The level of significance was α = 0.05. Seventy-five patients (49 women and 26 men) enrolled had a mean period of evaluation of 22.7 ± 6.2 months. Thirty-one implant-abutment (IA) sets had between 12-18 months, 34 between 19-24 months, and 44 between 25-33 months. Only one patient failed due to an abutment fracture after 25 months of function. Fifty-eight implants were placed in the maxilla (53.2%) and 51 in the mandible (46.8%). Seventy-four implants were installed in healed sites (67.9%), and 35 were in fresh socket sites (32.1%). Thirty-two out of these 35 implants placed in fresh sockets had the gap filled with bone graft particles. Twenty-six implants received immediate provisionalization. The average MBL was -0.67 ± 0.65 mm in mesial and -0.70 ± 0.63 mm in distal (p = 0.5072). The most important finding was the statistically significant difference comparing the values obtained for MBL between the abutments with different transmucosal height portions, which were better for abutments with heights greater than 2.5 mm. Regarding the abutments' diameter, 58 had 3.5 mm (53.2%) and 51 had 4.5 mm (46.8%). There was no statistical difference between them, with the following means and standard deviation, respectively, -0.57 ± 0.53 mm (mesial) and -0.66 ± 0.50 mm (distal), and -0.78 ± 0.75 mm (mesial) and -0.746 ± 0.76 mm (distal). Regarding the implant dimensions, 24 implants were 3.5 mm (22%), and 85 implants (78%) had 4.0 mm. In length, 51 implants had 9 mm (46.8%), 25 had 11 mm (22.9%), and 33 implants were 13 mm (30.3%). There was no statistical difference between the abutment diameters (p > 0.05). Within the limitations of this study, it was possible to conclude that better behavior and lesser marginal bone loss were observed when using abutment heights greater than 2.5 mm of transmucosal portion and when placed implants with 13 mm length. Furthermore, this type of abutment showed a little incidence of failures within the period analyzed in our study.

Randomized Clinical Trial Comparing Insertion Torque and Implant Stability of Two Different Implant Macrogeometries in the Initial Periods of Osseointegration.

Objectives: The present study compared two implants with different macrogeometries placed in healed alveolar sites, evaluating the insertion torque (ITV) and implant stability quotient (ISQ) values at three different periods. Methods: Seventy patients with a total of 100 dental implants were allocated into two groups (n = 50 per group): DuoCone implants (DC group) that included 28 implants in the maxilla and 22 in the mandible, and Maestro implants (MAE group) that included 26 in the maxilla and 24 in the mandible. The ITV was measured during the implant placement, and the ISQ values were measured immediately at implant placement (baseline) and after 30 and 45 days. Results: The mean and standard deviations of the ITV were statistically significant (p < 0.0001), 56.4 ± 6.41 Ncm for the DC group and 29.3 ± 9.65 Ncm for the MAE group. In the DC group, the ISQs ranged between 61.1 ± 3.78 and 69.8 ± 3.86, while the MAE group presented similar values compared with the other group, ranging between 61.9 ± 3.92 and 72.1 ± 2.37. Conclusions: The value of implant insertion torque did not influence the ISQ values measured immediately after implant placement. However, the ITV influenced the ISQ values measured in the two initial periods of osseointegration, with implants installed with lower torques presenting higher ISQ values.

Bacterial infiltration and detorque at the implant abutment morse taper interface after masticatory simulation.

This study evaluated the bacterial infiltration and the detorque of indexed and non-indexed abutments of Morse taper implants (MTI) after mechanical cycling (MC). 40 MTI were distributed into four groups: IIA (indexed implant abutments); NIIA (non-indexed implant abutments); IIAMC (indexed implant abutments submitted to MC); NIIAMC (non-indexed implant abutments submitted to MC), which were carried out under one million 5 Hz frequency and 3 Bar pressure. After mechanical cycling, all groups were immersed in a bacterial solution in Brain Heart Infusion Agar. After detorque, the bacteria infiltration was evaluated by counting the colony-forming units. For the bacterial infiltration, analysis was applied to the Kruskal-Wallis test (p = 0.0176) followed by Dunn's test. For the detorque analysis, the two-way repeated-measures ANOVA was applied, followed by the Tukey's test (p < 0.0001). Bacteria infiltration was highly observed in NIIA (p = 0.0027) and were absent in IIAMC and NIIAMC. The detorque values for IIA (19.96Ncm ± 0.19Ncm), NIIA (19.90Ncm ± 0.83Ncm), and NIIAMC (19.51Ncm ± 0,69Ncm) were similar and remained close to the initial value, while IIAMC (55.2Ncm ± 2.36Ncm) showed an extremely significant torque value increase (p < 0.0001). The mechanical cycling resulted in mechanical sealing of the implant-abutment interface, preventing bacterial infiltration in the indexed and non-indexed specimens, and increasing the detorque strength in the group of indexed abutments.

An Intraoral Repair Method for Chipping Fracture of a Multi-unit Fixed Zirconia Reconstruction: A Direct Dental Technique.

Fracture or chipping of veneering ceramic is one of the most frequent clinical failures in dentistry in fixed dental and implant-borne prostheses. Due to the friable nature of the ceramic material, chippings may result in an aesthetic and functional problem for the patient requiring a rapid solution. Direct repairs have been indicated for the restoration of function, aesthetics and comfort, especially in cases where the fractured prosthesis presents good adaptation and satisfactory aesthetics. This case report aims to present and discuss the techniques of the direct reveneering method, their advantages and disadvantages, as well as the importance of adhesive procedures in the success of these restorative approaches. Success in repairing the fractured area, regardless of the technique used, is fundamental to establish a strong and stable adhesion between the repaired and the fractured areas, since the longevity of the repair will depend on the quality of the interface generated.

A Digital Method to Fabricate the Ocular Portion of An Orbital Prosthesis with A Smartphone Camera, Color Calibration and Digital Printing.

Conventional techniques described in the literature for the manufacture of ocular prostheses are time-consuming since they involve manual work. The use of technologies could improve this laborious process, providing better esthetic outcomes. This technique describes how to manufacture the ocular portion of an orbital prosthesis using a smartphone camera, color calibration with a tooth shade guide, and digital printing. This method allows clinicians to fabricate customized ocular prosthesis by using a photograph of the patient's eye, thus eliminating the need for hand-painting and manual work, and reducing fabrication time.

Evaluation of the Accuracy of Conventional and Digital Impression Techniques for Implant Restorations.

PURPOSE: The increased use of CAD systems can generate doubt about the accuracy of digital impressions for angulated implants. The aim of this study was to evaluate the accuracy of different impression techniques, two conventional and one digital, for implants with and without angulation. MATERIALS AND METHODS: We used a polyurethane cast that simulates the human maxilla according to ASTM F1839, and 6 tapered implants were installed with external hexagonal connections to simulate tooth positions 17, 15, 12, 23, 25, and 27. Implants 17 and 23 were placed with 15° of mesial angulation and distal angulation, respectively. Mini cone abutments were installed on these implants with a metal strap 1 mm in height. Conventional and digital impression procedures were performed on the maxillary master cast, and the implants were separated into 6 groups based on the technique used and measurement type: G1 - control, G2 - digital impression, G3 - conventional impression with an open tray, G4 - conventional impression with a closed tray, G5 - conventional impression with an open tray and a digital impression, and G6 - conventional impression with a closed tray and a digital impression. A statistical analysis was performed using two-way repeated measures ANOVA to compare the groups, and a Kruskal-Wallis test was conducted to analyze the accuracy of the techniques. RESULTS: No significant difference in the accuracy of the techniques was observed between the groups. Therefore, no differences were found among the conventional impression and the combination of conventional and digital impressions, and the angulation of the implants did not affect the accuracy of the techniques. CONCLUSIONS: All of the techniques exhibited trueness and had acceptable precision. The variation of the angle of the implants did not affect the accuracy of the techniques.

Estudo de comparação por extensometria entre dois modelos de implante: extraoral e intraoral (estudo piloto) / Comparison study for extensometry between two implant models: extra-oral and intraoral (pilot study)

Objetivo: avaliar, por meio de extensometria, a infl uência da flange do implante de titânio na deformação superficial do osso. Material e métodos: um bloco de poliuretano simulando um osso tipo I mais corticalizado e menos medular (40 PCF) recebeu um implante de hexágono externo intraoral, sem flange 3,75 mm x 8,5 mm (G1) e um implante de hexágono externo extraoral, com flange 3,75 mm x 8 mm (G2). Em seguida, foram instalados componentes standard com 2 mm de altura de cinta metálica e cilindros metálicos para restauração provisória. Dois extensômetros lineares foram colados na superfície do bloco (mesial e distal de cada implante), e uma carga axial de 100 Ncm em uma máquina de ensaio universal foi aplicada, com cinco medições de microdeformação (µÎµ) para cada implante. Os dados foram submetidos ao teste Shapiro-Wilk para verifi car a homogenidade dos dados e em seguida ao teste t Student. Resultados: as médias e desvios-padrão obtidos foram: G1: 148,2 ± 5,84 e G2: 92,4 ± 11,24 µÆ, com diferença estatística significativa entre os grupos. Conclusão: os implantes extraorais tiveram melhor comportamento mecânico para as cargas axiais do que os implantes intraorais, sendo que a flange melhorou a distribuição da carga na superfície do bloco de poliuretano.

Objectives: to evaluate, by means of extensometry, the influence of the titanium implant flange on the superficial deformation of the bone. Material and methods: a polyurethane block simulating a more corticalized and less spinal type I bone (40 PCF) received an external intraoral hexagon implant with a 3.75 mm x 8.5 mm fl ange (G1) and an extraoral external hexagon implant, with flange 3.75 mm x 8 mm (G2). Subsequently, standard components with 2 mm high of metal strap and metal cylinders were installed for temporary restoration. Two linear strain gauges were glued to the surface of the block (mesial and distal of each implant), and an axial load of 100N in a universal test machine was applied with five microdemorphometric measurements (µÎµ) for each implant. The data were submitted to the Shapiro-Wilks test to verify the homogeneity of the data and then to the t-student test. Results: the means and standard deviations obtained were: G1: 148.2 ± 5.84 and G2: 92.4 ± 11.24 µÎµ, with signifi cant statistical difference between the groups. Conclusion: extraoral implants had better mechanical behavior for axial loads than intraoral implants, and the flange improved the load distribution on the surface of the polyurethane block.

Laminated Veneers with Stratified Feldspathic Ceramics.

Currently, there has been a growing demand for restorations of anterior teeth in the routine of doctors in dental offices. With advances in adhesive technology and good properties of the available ceramics, the use of ceramic veneers has been offered as a treatment option for cases where teeth have minor color changes and shape and position changes. Through careful treatment planning, it is possible to conservatively use ceramic veneers in the treatments, applying techniques with minimal wear of the teeth and obtaining excellent aesthetic results with mechanical stability and biocompatibility with the periodontal tissues and clinical longevity. This clinical case report was used to design the digital smile, which guided the production of the diagnostic waxing of the superior model. Silicone guides were then made to create the mock-up, orienting enamel/dentin wear and assisting the preparation of the crowns with bis-acryl resin. When the wear was finished, the gingival separation was performed using the double-thread technique. In the molding process, the second wire was withdrawn and the molding material flowed into the gingival groove, copying the terminal region. After analysis of the quality of the impression, the temporary crowns were made with bis-acryl resin, using the guide. The color of the cementing agent was chosen using a glycerin-based compound which simulates the final color of the cement. After two hours of drying, two different layers of silane were applied for 60 seconds. After the preparation of the piece, gingival isolation and separation were done. The dental substrate was degreased with detergent solution and conditioned with 37% phosphoric acid for 15 seconds and then washed for 45 seconds for subsequent drying, leaving the substrate moistened. The adhesive system was applied for 30 seconds, waiting for the adhesive to penetrate into the conditioned dentinal tubules. A light air jet was applied, and then each tooth was photopolymerized for 30 seconds. The resin cement was placed inside the pieces and placed in position and photopolymerized. The excess cement was removed; after a layer of glycerin in the cervical region, aiming to block the entry of oxygen and polishing was performed. The purpose of this case report was to describe a sequence of clinical steps, from planning to cementation, in a case of aesthetic correction using feldspathic ceramic veneers.

Avaliação da deformação superficial do osso gerada por cargas axiais em implantes de diferentes comprimentos / Evaluation of superfi cial bone deformation for axial loads with different implants lengths

Objetivo: avaliar, por meio de extensometria, a transmissão da carga mastigatória axial ao osso de suporte em próteses unitárias implantossuportadas por implantes de diferentes comprimentos. Material e métodos: em um bloco de poliuretano que simula 2 mm de osso cortical e o restante de medular, segundo a norma ASTM­F1839, com 22 mm x 16 mm x 150 mm, foram instalados quatro implantes cone-morse infraósseos 2 mm: G1) 4 mm x 7 mm; G2) 4 mm x 9 mm; G3) 4 mm x 11 mm; G4) 4 mm x 13 mm. Sobre os mesmos, foram instalados pilares do tipo esteticone e cilindros metálicos. Dois extensômetros lineares foram colados na superfície do bloco, tangenciando a plataforma de cada implante (mesial e distal). Em uma máquina de ensaio universal, foi aplicada uma carga de 100 N sobre a superfície oclusal de cada cilindro. Para cada grupo, foram realizados cinco medições e os dados obtidos em microdeformacão (µÆ). Foi verificada a normalidade dos dados pelo teste de Shapiro-Wilk e realizada a análise de variância 1 critério (p < 0,05), e o teste Tukey (p  0,5). Resultados: as médias e os desvios-padrão das amostras foram, respectivamente, G1: 346.16,3 ± 10,28 µÆ; G2: 216.91 ± 15,47 µÆ; G3: 114,41 ± 2,33 µÆ; e G4: 76.83,3 ± 7,13 µÆ. O teste de Shapiro-Wilk constatou a normalidade dos dados, e os testes Anova e Turkey a diferença estatística significante entre todos os grupos. Conclusão: para cargas axiais, implantes com menor comprimento produziram maior deformação no osso superfi cial.

Purpose: the aim of this study was to evaluate, by extensometry, the transmission of the axial masticatory load to supporting bone around implants of different lengths. Material and methods: in a block of polyurethane that simulates 2 mm of cortical bone and the remaing of medullary bone, according to the ASTM-F1839 standard, with 22 mm x 16 mm x 150 mm, were installed 4 morse tappered dental implants, 2 mm subcrestal: G1) 4 mm x 7 mm; G2) 4 mm x 9 mm; G3) 4 mm x 11 mm; G4) 4 mm x 13 mm. Estheticone-like abutments and metallic cylinders were placed. Two linear strain gauges were bonded on block surface, tangential to the platform of each implant (mesial and distal). A 100 N load on the occlusal surface of each cylinder was applied to a universal test machine. For each group, five measurements and the data obtained in microdeformation (µÆ) were performed. The normality of the data was verified by the Shapiro-Wilk test and (p < 0.05) and Tukey's test (p  0.5). Results: the means and standard deviation of the samples were respectively G1: 346.16.3 ± 10.28 µÆ; G2: 216.91 ± 15.47 µÆ; G3: 114.41 ± 2.33 µÆ; G4: 76.83.3 ± 7.13 µÆ. The Shapiro-Wilk test exhibit the normality of the data, and the Anova and Turkey tests exhibit statistically significant difference between all groups. Conclusion: axial load produced more tension for short implants on the superficial bone.

Aumento de coroa estético associado à reabilitação protética ­ relato de caso clínico / Aesthetic crown lengthening associated with prosthetic rehabilitation ­ a case report

Atualmente, a estética periodontal ou estética vermelha tem sido muito discutida e valorizada na busca pela harmonia do sorriso. Em situações de erupção passiva alterada, ou seja, existência de grande exposição de gengiva acompanhada de coroas clínicas curtas, há uma indicação precisa para a execução de aumento de coroa clínica. A Odontologia estética reabilitadora exerce um papel fundamental no tratamento multidisciplinar. Este trabalho teve como objetivo relatar um caso clínico de sorriso gengival causado pela erupção passiva alterada, associando reabilitação estética com facetas dentárias. Após a conclusão do tratamento, foi possível afirmar que a interação Prótese/Periodontia foi de fundamental importância para a obtenção do resultado final esperado pela paciente.

Nowadays, the periodontal or red esthetics has been highlightened in the search of smile harmony. In cases of altered passive eruption, which means the existence of great gum exhibition and short clinical crowns, there is precise indication for crown lengthening. Esthetic dentistry has a fundamental role in the multidisciplinary treatment. This paper reports on a clinical case of gummy smile due to passive eruption receiving an oral rehabilitation with laminate veneers. After treatment delivery, it was possible to recognize that the Prosthodontic/Periodontal relationship is of critical importance for the patient's desired outcome.

Reação alérgica a resina acrílica em paciente com coroa provisória: relato de caso / Allergic reaction to acrylic resin in a patient with a provisional crown: case report

As resinas acrílicas são amplamente utilizadas na odontologia, especialmente em ortodontia e prótese. Este artigo relata o caso de um paciente de 33 anos de idade, do gênero masculino que relatava desconforto e dores na região de pré-molar superior esquerdo após a colocação de um provisório, com presença de uma lesão eritomatosa. Após biópsia incisional constatouse a processo inflamatório crônico inespecífico. A causa apresentada para tal patologia foi o provisório confeccionado com resina acrílica autopolimerizável à base de metil-metacrilato. (AU)

Acrylic resins are widely used in dentistry, especially in orthodontics and prosthetics. Patients: this article reports the case of a leukodermic 33-year-old male who reported discomfort and pain due to an erythematous lesion in the upper first left premolar (24) after the placement of an acrylic resin temporary restoration. Discussion: The signs and symptoms presented by the patient and his report of visiting the rural countryside generated concern regarding the possible diagnosis, which led to a more invasive biopsy to differentiate allergic inflammation from a paracoccidioidomycosis. Biopsy revealed a chronic inflammatory process. Conclusion: the pathology was caused by contact with methyl methacrylate-based provisional acrylic resin. After cementation of the final crown, the inflammatory signs and symptoms disappeared .(AU)

Zirconia Rehabilitation Focused on the Emergence Profile: A Case Report.

The first choice for anterior rehabilitation has been metal-free materials due to their successful aesthetic results. However, the definitive clinical work accuracy may be affected by the lack of clinicians' expertise and familiarization with the latest techniques, as well as recurrent laboratory procedures. This manuscript presents a clinical experience with zirconia ceramic for anterior crowns and zirconia CAD/CAM abutments, including both clinical and laboratory steps after the implant installation. The 'emergence profile' and the 'double scanning' techniques obtained by the waxing technique appear to be a very promising procedure for aesthetic improvement of the single-implant zirconia restoration in anterior teeth.

Effect of Different Abutments and Connections in Deformation Crestal Bone.

STATEMENT OF PROBLEM: The use of Morse taper connections is increasing, but little is known about the biomechanical use of abutments and their use in fixed prostheses. PURPOSE: This study evaluated the transmission of load on the bone implant-supported dentures, varying the type of prosthetic connection and abutment. MATERIAL AND METHODS: Using 4 polyurethane models, 3 implants were inserted into each block, establishing the following groups: (a) external hexagon and Micro-Unit abutments; (b) external hexagon and UCLA abutment; (c) Morse taper and Micro-Unit abutments; and (d) Morse taper and UCLA abutments. The prosthetic structures were cast, and in a universal testing machine, load was applied midway between the implants, with cantilever intervals of 5, 10, 15, 20, and 25 mm. Data were analyzed by Mann-Whitney, Friedman, and Kruskal-Wallis tests (P < 0.05). RESULTS: Regarding the prosthetic connection, there was no difference in the use of hexagonal or Morse taper, but the use of Micro-Unit abutment showed lower deformation values than UCLA for the 2 connections. CONCLUSIONS: The use of intermediate abutments affects the distribution of masticatory loads: the greater the length of the cantilever, the greater the surface deformation of the bone around the distal implant.

Effect of Jig Design and Assessment of Stress Distribution in Testing Metal-Ceramic Adhesion.

PURPOSE: In testing adhesion using shear bond test, a combination of shear and tensile forces occur at the interface, resulting in complex stresses. The jig designs used for this kind of test show variations in published studies, complicating direct comparison between studies. This study evaluated the effect of different jig designs on metal-ceramic bond strength and assessed the stress distribution at the interface using finite element analysis (FEA). MATERIALS AND METHODS: Metal-ceramic (Metal: Ni-Cr, Wiron 99, Bego; Ceramic: Vita Omega 900, Vita) specimens (N = 36) (diameter: 4 mm, veneer thickness: 4 mm; base diameter: 5 mm, thickness: 1 mm) were fabricated and randomly divided into three groups (n = 12 per group) to be tested using one of the following jig designs: (a) chisel (CH) (ISO 11405), (b) steel strip (SS), (c) piston (PI). Metal-ceramic interfaces were loaded under shear until debonding in a universal testing machine (0.5 mm/min). Failure types were evaluated using scanning electron microscopy (SEM). FEA was used to study the stress distribution using different jigs. Metal-ceramic bond strength data (MPa) were analyzed using ANOVA and Tukey's tests (α = 0.05). RESULTS: The jig type significantly affected the bond results (p = 0.0001). PI type of jig presented the highest results (MPa) (p < 0.05) (58.2 ± 14.8), followed by CH (38.7 ± 7.6) and SS jig type (23.3 ± 4.2) (p < 0.05). Failure types were exclusively a combination of cohesive failure in the opaque ceramic and adhesive interface failure. FEA analysis indicated that the SS jig presented slightly more stress formation than with the CH jig. The PI jig presented small stress concentration with more homogeneous force distribution compared to the CH jig where the stress concentrated in the area where the force was applied. CONCLUSION: Metal-ceramic bond strength was affected by the jig design. Accordingly, the results of in vitro studies on metal-ceramic adhesion should be evaluated with caution. CLINICAL SIGNIFICANCE: When adhesion of ceramic materials to metals is evaluated in in vitro studies, it should be noted that the loading jig type affects the results. Clinical observations should report on the location and type of ceramic fractures in metal-ceramic reconstructions so that the most relevant test method can be identified.

Influence of implant-retained silicone oculo-palpebral prosthesis on stress distribution: a pilot study using a photoelastic model.

PURPOSE: The purpose of this pilot study was to evaluate the behavior of stresses surrounding orbital model implants subjected to a load of a silicone oculo-palpebral prosthesis. MATERIALS AND METHODS: A photoelastic model was constructed mimicking the orbital cavity of an adult patient who underwent left orbital resection. Two 3.75 × 5-mm extraoral implants with 3.75 × 5.25-mm magnetic connectors were placed in the model to anchor a silicone oculo-palpebral prosthesis. The stress generated by prosthesis retention was evaluated using photoelasticity at 15, 30, and 60 minutes. The polariscope images were analyzed qualitatively at five areas surrounding the implants. These same areas were analyzed quantitatively using Matlab software based on the RGB color pattern. Data were compared with the Wilcoxon test. RESULTS: Using fringe localization, the qualitative analysis demonstrated that the area between the implants had the greatest stress. The quantitative analysis showed that the peri-implant stress increased significantly in proportion to the increase in prosthesis retention time. CONCLUSION: The oculo-palpebral prosthesis generated stress around the implants, and the stress intensity was directly proportional to the duration of use.

Sistema CAD/CAM: uma alternativa para infraestruturas metálicas fundidas para próteses totais fixas implantossuportadas / The CAD/CAM system: an alternative to cast metal frameworks for complete fixed dental implant-supported prosthesis

Este trabalho relata um caso clínico do uso do sistema CAD/CAM para confecção da infraestrutura metálica. Um paciente de 57 anos de idade apresentava-se com uma prótese total metalocerâmica superior de longa data e próteses mandibulares bilaterais sobre dois implantes cada, afetados pela peri-implantite. O planejamento incluiu a remoção dos implantes afetados e a colocação de quarto novos implantes entre os forâmenes mentonianos, mas sem carregamento imediato em função da atividade parafuncional do paciente. A infraestrutura metálica foi fresada a partir de uma bolacha de CoCr em dez minutos. Cada cantiléver apresentou extensão de 20 mm. A adaptação passiva da prótese mandibular definitiva confirmou as possibilidades e benefícios da tecnologia CAD/CAM para próteses totais fixas implantossuportadas.

This paper reports a clinical case where a CAD/CAM system was used to fabricate a metallic framework. A 57 years-old patient presented with an old tooth-supported fused-to-metal prosthesis in the maxilla and bilateral mandibular implant-supported prostheses (two implants each) affected by peri-implantitis. The treatment planning included removal of infected implants and placement of four new dental implants between mental foramina, but with no immediate loading due to the patient´s parafunctional activities. The metallic infra-structure was milled from a CoCr disk in ten minutes. Each cantilever had a 20 mm-length. The passive fit of the definitive mandibular prosthesis was deemed excellent and confirmed the possibilities and benefi ts of the CAD/CAM technology for complete fixed implant-supported prostheses.

Oclusão em próteses sobre implantes

A manutenção das restaurações implantossuportadas depende do equilíbrio e da manutenção da homeostasia dos tecidos peri-implantares, sendo assim, dependente de uma oclusão ajustada a cada situação. Conceitos oclusais, assim como relacionados a restaurações unitárias, serão discutidos e apresentados por meio de casos clínicos.